global environmental crisis essay

Environmental Issues Essay for Students and Children

500+ words essay on environmental issues.

The environment plays a significant role to support life on earth. But there are some issues that are causing damages to life and the ecosystem of the earth. It is related to the not only environment but with everyone that lives on the planet. Besides, its main source is pollution , global warming, greenhouse gas , and many others. The everyday activities of human are constantly degrading the quality of the environment which ultimately results in the loss of survival condition from the earth.

Source of Environment Issue

There are hundreds of issue that causing damage to the environment. But in this, we are going to discuss the main causes of environmental issues because they are very dangerous to life and the ecosystem.

Pollution – It is one of the main causes of an environmental issue because it poisons the air , water , soil , and noise. As we know that in the past few decades the numbers of industries have rapidly increased. Moreover, these industries discharge their untreated waste into the water bodies, on soil, and in air. Most of these wastes contain harmful and poisonous materials that spread very easily because of the movement of water bodies and wind.

Greenhouse Gases – These are the gases which are responsible for the increase in the temperature of the earth surface. This gases directly relates to air pollution because of the pollution produced by the vehicle and factories which contains a toxic chemical that harms the life and environment of earth.

Climate Changes – Due to environmental issue the climate is changing rapidly and things like smog, acid rains are getting common. Also, the number of natural calamities is also increasing and almost every year there is flood, famine, drought , landslides, earthquakes, and many more calamities are increasing.

Above all, human being and their greed for more is the ultimate cause of all the environmental issue.

Get the huge list of more than 500 Essay Topics and Ideas

How to Minimize Environment Issue?

Now we know the major issues which are causing damage to the environment. So, now we can discuss the ways by which we can save our environment. For doing so we have to take some measures that will help us in fighting environmental issues .

Moreover, these issues will not only save the environment but also save the life and ecosystem of the planet. Some of the ways of minimizing environmental threat are discussed below:

Reforestation – It will not only help in maintaining the balance of the ecosystem but also help in restoring the natural cycles that work with it. Also, it will help in recharge of groundwater, maintaining the monsoon cycle , decreasing the number of carbons from the air, and many more.

The 3 R’s principle – For contributing to the environment one should have to use the 3 R’s principle that is Reduce, Reuse, and Recycle. Moreover, it helps the environment in a lot of ways.

To conclude, we can say that humans are a major source of environmental issues. Likewise, our activities are the major reason that the level of harmful gases and pollutants have increased in the environment. But now the humans have taken this problem seriously and now working to eradicate it. Above all, if all humans contribute equally to the environment then this issue can be fight backed. The natural balance can once again be restored.

FAQs about Environmental Issue

Q.1 Name the major environmental issues. A.1 The major environmental issues are pollution, environmental degradation, resource depletion, and climate change. Besides, there are several other environmental issues that also need attention.

Q.2 What is the cause of environmental change? A.2 Human activities are the main cause of environmental change. Moreover, due to our activities, the amount of greenhouse gases has rapidly increased over the past few decades.

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• Security Council

Climate Change ‘Biggest Threat Modern Humans Have Ever Faced’, World-Renowned Naturalist Tells Security Council, Calls for Greater Global Cooperation

Climate change is a “crisis multiplier” that has profound implications for international peace and stability, Secretary-General António Guterres told the Security Council today, amid calls for deep partnerships within and beyond the United Nations system to blunt its acute effects on food security, natural resources and migration patterns fuelling tensions across countries and regions.

Throughout the morning, the Council’s high-level open debate on climate and security heard from a range of influential voices, including naturalist David Attenborough, who called climate change “the biggest threat to security that modern humans have ever faced”.  In video remarks telecast at the outset, he warned that concentrations of carbon dioxide currently in the atmosphere have not been equalled for millions of years.

“If we continue on our current path, we will face the collapse of everything that gives us our security,” he said:  food production, access to fresh water, habitable ambient temperature and ocean food chains.  The poorest — those with the least security — are certain to suffer.  “Our duty right now is surely to do all we can to help those in the most immediate danger.”

While the world will never return to the stable climate that gave birth to civilization, he said that, if Governments attending the twenty-sixth Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) in November recognize climate change as a global security threat, “we may yet act proportionately — and in time”.

Climate change can only be dealt with by unparalleled levels of global cooperation, he said.  It will compel countries to question economic models, invent new industries and recognize the moral responsibility that wealthy nations have to the rest of the world, placing a value on nature that “goes far beyond money”.  He challenged the international community to finally create a stable, healthy world where resources are equally shared and where — for the first time in history — people “come to know what it feels like to be secure”.

Mr. Guterres echoed those calls, describing the climate emergency as “the defining issue of our time”.  Noting that the last decade was the hottest in human history, he said wildfires, cyclones, floods and droughts are now the new normal.  “These shocks not only damage the environment on which we depend, they also weaken our political, economic and social systems,” he said.

Indeed, where climate change dries up rivers, reduces harvests, destroys critical infrastructure and displaces communities, it exacerbates the risks of conflict, he said.  A study by the Stockholm International Peace Research Institute found that 8 of the 10 countries hosting the largest multilateral peace operations in 2018 were in areas highly exposed to climate change.

The impact is greatest where fragility and conflict have weakened coping mechanisms, he said, where people depend on natural capital for their livelihoods and where women — who bear the greatest burden of the climate emergency — do not enjoy equal rights.  He highlighted examples in Afghanistan, where reduced harvests have pushed people into poverty, leaving them susceptible to recruitment by armed groups, and across West Africa and the Sahel, where changes in grazing patterns have fostered conflict between pastoralists and farmers.  In some Pacific small island nations, entire communities have been forced to relocate.

“The forced movement of larger numbers of people around the world will clearly increase the potential for conflict and insecurity,” he observed.  He called for greater efforts to address climate‑related security risks, starting with a focus on prevention, and creating a global coalition committed to achieving net-zero emissions by mid-century.  The United Nations is asking companies, cities and financial institutions to prepare credible decarbonization plans.

In addition, immediate actions are needed to protect countries from increasingly frequent and severe climate effects.  He urged donors and multilateral and national development banks to increase the share of adaptation and resilience finance to at least 50 per cent of their climate finance support.  Developed countries, too, must keep their pledge to channel $100 billion annually to the global South.  “They have already missed the deadline of 2020,” he acknowledged.

Above all, he called for embracing a concept of security that places people at its centre, stressing that COVID-19 has laid bare the devastation that non‑traditional security threats can cause on a global scale.  In all such efforts, it will be essential to build on the strengths of the Security Council, Peacebuilding Commission, international financial institutions, regional organizations, civil society, the private sector, academia and others.

Issuing a call to action, Nisreen Elsaim, Chair of the Youth Organization on Climate Change and the United Nations Youth Advisory Group, said young people around the globe are watching the Security Council as it grapples with climate change.  Each of the organ’s four meetings on the issue — in 2007, 2011, 2018 and 2019 — have referenced serious climate-related security risks in Somalia, Darfur, West Africa and the Sahel, Mali and the Lake Chad Basin.  “Science has forecasted many more countries will join this list if we did not take the right measures now, and if we did not start adaptation specially in Africa,” she said, adding that, in her country, “we are living in continuous insecurity due to many factors that put Sudan on the top of the list when it comes to climate vulnerability”.

She recalled that, in a 2018 Council resolution on Sudan, members recognized the adverse effects of climate change, ecological changes and natural hazards on the situation in Darfur, focusing specifically on drought, desertification, land degradation and food insecurity.  “Human survival, in a situation of resources degradation, hunger, poverty and uncontrolled climate migration, will make conflict an inevitable result,” she said.  Moreover, climate-related emergencies cause major disruptions in access to health, life-saving sexual and reproductive health services, and result in loss of livelihoods and drive displacement and migration.  They also increase the risk of gender-based violence and harmful practices and force young people to flee in search of a decent life.

Welcoming the Council’s recent deployment of a new special political mission, the United Nations Integrated Transition Assistance Mission in the Sudan (UNITAMS), she said it has a historic opportunity to speak to the root causes of the conflict.  Climate change and youth participation is mentioned twice in the Mission’s mandate, and climate change challenges are included in the 2020 Juba Peace Agreement.  Emphasizing that young people must be part of the solution, she declared:  “We are the present, we have the future, let’s not repeat previous generations’ lapse.”

In the ensuing dialogue, Heads of State and Government, along with ministers and other senior officials described national actions to attenuate the negative impact of climate change and offered their views on the related security risks.  Some pressed the Council to broaden its thinking about non-traditional security threats.  Several — including leaders from Kenya and Niger — stressed that the link between climate and conflict could not be more evident, while others explored the ability of Governments to meet people’s basic needs, and still others cast doubt on the assertion that the relationship between climate and conflict is causal, instead pointing to political and economic factors that are known to drive tensions.

Boris Johnson, Prime Minister of the United Kingdom and Council President for February, speaking in his national capacity, said the Council, while imperfect, has been willing to lead the way in confronting threats to international security.  “That is exactly what climate change represents,” he said, acknowledging that, while there are some who disagree, these cynics “could not be more wrong”.  While the causes of climate change may not sit within the Council’s traditional purview, its effects most certainly do.  He asked delegates to consider the young man forced onto the road when his once‑fertile home becomes a desert — one of the 16 million people displaced by weather-related disasters each year — who becomes easy prey for violent extremists, or the girl who drops out of school because her daily search for water takes her away from her family — and into the sights of the human traffickers.

“If such scenes were triggered by the actions of some despotic warlord or internecine conflict, few would question this Council’s right to act or its duty to do so,” he assured.  “This is not a subject from which we should shy away.”  The world must move from 51 billion metric tons of greenhouse‑gas emissions each year to net zero, so that the increase in global temperatures remains within manageable levels.  For its part, the United Kingdom Parliament passed a law committing to net zero by 2050, he said, drawing attention to his pledge that the nation would slash emissions by 68 per cent by 2030.  He urged the Council to act, “because climate change is a geopolitical issue every bit as much as an environmental one”, stressing that, if it is to succeed in maintaining peace and security worldwide, it must galvanize and support the United Nations family of agencies into a swift and effective response.

Kaïs Saïed, President of Tunisia , agreed with Ms. Elsaim that the world must listen to youth on climate change.  More broadly, humans — and not money — must be placed at the centre of the issue.  Voicing support for the Secretary-General’s 2021 priorities, especially his efforts to galvanize Member States to confront the multiple impacts of climate change, he described it as ironic that humans are, at the same time, the phenomenon’s drivers and its greatest victims.  “It is no one’s right to […] to commit all of humanity to death,” he stressed, noting that Council resolution 2532 (2020) confirmed that insecurity can be driven by a multitude of factors, not just armed conflict.  One such driver is the deepening poverty and resource scarcity resulting from a changing climate, particularly in Africa.  Climate factors often prolong conflict and create conditions conducive to deprivation, exclusion, terrorism and organized crime.

Calling on the Council to adopt a new, more comprehensive approach and for sufficient resources for all specialized agencies related to climate change, he underlined the need for early warning systems and better prevention strategies.  Noting that the COVID-19 pandemic and other recent crises have once again revealed the need for States to strengthen their solidarity, he emphasized the need for prompt action while stressing that the burden borne by States must be differentiated based on their degree of responsibility for causing the crisis.  Moreover, mitigation cannot be at the expense of developing countries, he said.

Uhuru Kenyatta, President of Kenya , said that new approaches to investment by the public and private sector need to reach the countries and regions worst hit by climate change.  Persistent droughts, constant sea‑level rise and increasingly frequent extreme weather patterns are reversing economic growth and development gains achieved over decades.  The result is increased fragility to instability and armed conflict that then come to the attention of this Security Council.  The implementation of the Council’s mandate to maintain global peace and security will only get more difficult with time if climate change remains on its present course.  Rather than wait for a future tipping point, we must redouble the efforts to direct all the resources and multilateral frameworks of our rules-based international order to mitigate the effects of climate change.  While the bulk of this work is happening outside the Council, no body with such a strong mandate should step aside from this challenge.

The climate-security nexus is already impacting Africa.  “Listen to us Africans when we tell you that the link is clear, its impact tangible and the need for solutions urgent,” he said.  Making recommendations, he said that the Council must do more when crafting mandates for conflict resolution and post-conflict resolution to ensure they dovetail with the efforts to deploy climate change mitigation and adaptation measures.  In this regard, he applauded Council resolutions 2349 (2017) and 2502 (2019), respectively on Lake Chad and the Democratic Republic of the Congo, that have integrated measures to address the impact of climate change.  The 15-member organ can also act strongly against illicit financial outflows, illicit resource exploitation, terrorism financing and money‑laundering in the most fragile regions in Africa.  Doing so immediately boosts the resources available to Governments to undertake climate change mitigation and offer the public services and goods needed to consolidate and protect peace.

Brigi Rafini, Prime Minister of Niger , agreed that the impact of climate change on peace and security is increasingly evident, stressing that water scarcity exacerbated by climate change could see gross domestic product (GDP) in the Sahel fall by 6 per cent and hunger increase 20 per cent by 2050.  Climate change has increased competition for diminished land and water resources, ramping up tensions between livestock owners and others.  He underscored the collective responsibility to tackle this existential challenge, stressing that “climate change and land degradation are no longer purely environmental matters”.  Rather, they are part of a broader view that links environmental goals with those for economic and social development, and the pursuit of international peace and stability.

“We need to consider climate change as a threat to peace and security,” he said, urging the Council to shore up its understanding of impact on security and to systematically consider climate change in its resolutions pertaining to specific country and regional contexts.  In such efforts, it should rely on the advisory role of the Peacebuilding Commission, and the Informal Expert Group on Climate and Security, co-chaired by Niger and Ireland.  The appointment of a Special Envoy of the Secretary-General for Climate and Security likewise will raise the profile of this dimension within the Council’s work.

Nguyễn Xuân Phúc, Prime Minister of Viet Nam , said the Earth’s recent calamities have placed great burdens on the political and socioeconomic life of many countries, causing unemployment and poverty, creating instability and exacerbating current conflicts.  Against that backdrop, the Council should galvanize the international community’s collective efforts with an approach that is balanced between traditional and non-traditional security challenges.  That includes addressing the root causes of conflicts such as poverty, inequality, power politics and unilateral interference and coercion.

Calling for strict adherence to the Charter of the United Nations and international law, he said the 2030 Agenda for Sustainable Development, the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement on climate change must guide the way, and greater resources are needed to support developing countries, least developed countries, small island developing States and landlocked countries.  The Council should also enhance its early warning capacity, bolster its mediation and conflict prevention roles, work more closely with regional organizations and fully respect States’ sovereignty and national ownership.  Noting that Viet Nam is among the six countries most severely affected by climate change, he outlined various national efforts to address the challenge while requesting more international assistance.

Erna Solberg, Prime Minister of Norway , emphasized that climate change is redefining the global security landscape.  “We must rethink and adapt the Council’s approaches to peacebuilding and sustaining peace in three ways,” she said.  First, the Council needs better information on climate-related security risks.  International research networks and the informal expert group will be important in that regard.  Norway has helped establish a Nordic-Baltic expert network.  Second, the Council should discuss climate risks in specific country contexts, based on country reporting and briefings.  The United Nations must be at the forefront of preventive diplomacy.  To achieve sustainable solutions, peace diplomacy must be climate-sensitive, and climate action must be conflict‑sensitive.  Third, it is imperative to strengthen partnerships within and beyond the United Nations system, including with affected States and regional organizations.  The active participation of diverse groups, including women and youth, is also vital.

The national security communities in many countries have understood the security risks posed by climate change, she continued.  While climate change can lead to hard security challenges, there are no hard security solutions.  The first line of defence is ambitious climate action.  It must begin with the full implementation of the Paris Agreement and 2030 Agenda.  Climate action depends on multilateral cooperation.  By shouldering a common responsibility to counter climate change, the Council will be better prepared to maintain international peace and stability.

Ralph E. Gonsalves, Prime Minister and Minister for Foreign Affairs of Saint Vincent and the Grenadines , emphasizing that the Council has a responsibility to address the consequences of climate change, said a failure to do so would be, in part, “an abdication of our duty”.  It is time for the organ to seriously consider drafting a resolution on the matter and to map out a coherent approach, aiming for a working consensus.  Affirming UNFCCC’s role as the primary body for dealing with climate change and the Paris Agreement as a major part of the rules-based international system, he said the Council should play its role without encroaching on the work of UNFCCC’s inclusive decision-making body.  It should also engage with the Peacebuilding Commission and the General Assembly on climate and security risks that touch on issues of humanitarian support, sustainable development, health pandemics, peace and security.

Stressing that the first step to prevent or contain climate-security risks is for the major, and historical, emitters to fulfil — and indeed exceed — the commitments made in the Paris Agreement, he underlined the principle of common but differentiated responsibility.  Climate change is an existential threat that disproportionately affects the most vulnerable, especially small island developing States such as Saint Vincent and the Grenadines.  “It has become distressingly commonplace for an entire year’s [gross domestic product] to be washed away by a hurricane overnight, even as we are hindered by a lack of a sufficient inclusion, on favourable terms, into the global financial architecture,” he said.  Citing the many natural hazards in Haiti, in particular, he also drew attention to the Sahel region and the battle for dwindling resources.  However, no country is immune to such human-made challenges and all must stand in solidarity, with the Council paying close attention to climate change as it crafts its mandates, he said.

Kaja Kallas, Prime Minister of Estonia , said 7 of the 10 countries most vulnerable and least prepared to deal with climate change host a United Nations peacekeeping operation or a special political mission — a fact the Council cannot ignore.  She expressed support for the statement to be delivered by Germany’s Foreign Minister on behalf of like-minded countries pointing the way forward for the Council, stressing that “we need to acknowledge that the climate emergency can pose a danger to peace — and we must make it a part of our security policy planning and discussions here”.  She pressed the Council to “do more” to fully

aspects of its work, noting that the Secretary-General must receive a mandate to collect data and coordinate policy to this aim.

Among other efforts, she said that Estonia cooperates with small island States and least developed countries in green technology solutions and know-how transfer.  The Government also recently launched the Data for the Environment Alliance, a coalition of State and non-State actors that will support the United Nations Environment Programme (UNEP) in developing a global environmental data strategy by 2025.

Simon Coveney, Minister for Foreign Affairs and Defence of Ireland , said that climate change has many complex impacts, not least on international peace and security, the very business of this Council.  Climate change is already causing upheaval, affecting peace and security and the stability of societies.  Pointing out that the relationship between climate and security works in complex ways, he said political instability undermines efforts to build climate resilience, and the impact of climactic shocks is compounded when institutions are strained.  Ireland is proud to join the Weathering Risk Project to help guide action at the Security Council and beyond, and is keen to understand better not just how climate change contributes to insecurity but how climate action can build peace.  Ireland chairs the Informal Expert Group of Member States on this topic, together with Niger, also partnering with Nauru and Germany, as Chairs of the Group of Friends on Climate and Security.

Ireland’s core message today is that the inclusion of climate in Council discussions and actions will strengthen conflict prevention and support peacebuilding efforts.  Stressing the need to ensure the full, equal and meaningful participation of women and youth in decision-making processes related to climate issues and the management of natural resources, he declared:  “But, in listening to and understanding the concerns and insights of future generations, we cannot abrogate our responsibility to provide leadership today”.

Marcelo Ebrard Casaubón, Minister for Foreign Affairs of Mexico , said the COVID-19 pandemic has revealed that international peace and security can no longer be viewed through a single lens, but must also consider multiple drivers of insecurity.  Food insecurity, water scarcity and droughts — all exacerbated by climate change — have reached severe levels in several regions of the world.  Pledging Mexico’s support to the next Conference of Parties to the UNFCCC in Glasgow, later in 2021, he said climate change requires a comprehensive global response with a focus on ecosystem preservations.  Mexico recently submitted its own national plan in that arena, which is coupled with a focus on prevention and adaptation, as well as efforts to reduce inequality and strengthen communities.  Stressing that all efforts must be taken in line with the 2030 Agenda, he welcomed the Council’s creation of an informal group to monitor the links between climate and peace and security as a timely measure.  Underlining the importance of ensuring sustainable peacebuilding and protecting livelihoods, he agreed with the Secretary-General that post-pandemic recovery efforts are an opportunity to “build back better” and build more egalitarian, adaptable societies.

Emmanuel Macron, President of France , said protecting the environment has, in recent years, meant recognizing climate change as a peace and security issue.  Of the 20 countries most affected by conflict in the world, 12 are also severely impacted by climate change, he said, spotlighting the impacts of desertification, the increase in forced migration and agricultural challenges — all of which have resulted in such fallout as the advent of climate refugees and growing conflicts over land and water.  Endorsing the initiative to address such matters under the auspices of the Council, he echoed calls for the appointment of a United Nations Special Envoy for Climate Security, as well as for an annual Secretary-General’s report with relevant recommendations.

Recognizing that the effects of climate change are unfairly distributed worldwide, he recalled his recent call for France’s contribution to the Green Climate Fund to be increased to one third of its total.  France strongly supports the creation of a “Great Green Wall” in Africa, which aims to restore 250 million hectares of land for agriculture, create 10 million green new jobs and sequester carbon.  He also pledged France’s commitment to accelerating the preservation of biodiversity, while calling for strengthened dialogue between the African Union and the United Nations on climate and security.  Turning to the Pacific, where many nations are struggling to implement mitigation measures, he called for additional international support and an easing of geopolitical tensions across the region.

Prakash Javadekar, Minister for Environment, Forests and Climate Change of  India , recalled the global democratic effort to take climate action in a nationally determined manner, based on the principle of common but differentiated responsibility and respective capabilities.  He cautioned the Council against building a parallel climate track where such principles are “brushed aside”.  Noting that there is no common, widely accepted methodology for assessing the links between climate change, conflict and fragility, he said fragility and climate impact are highly context‑specific.  In fragile contexts, where Governments struggle to provide basic services, emergency conditions are largely driven by political violence disrupting harvests and aid supplies, rather than by climate factors alone.  “A complete picture of climate vulnerability only emerges with an assessment of the State’s capacity to be the primary responder to interrelated environmental, social, economic and security dynamics,” he said.  While climate change does not directly cause violent conflict, its interaction with other social, political and economic factors can exacerbate conflict drivers.  He called for the building of robust governance structures at local, national and regional levels to address climate‑ and fragility-related risks, pressing donor countries to provide greater financial, technological and capacity-building assistance to help fragile States enact adaption and mitigation strategies.

John F. Kerry, Special Presidential Envoy for Climate of the United States , thanked European and other countries for their leadership on climate change during what he described as the United States “inexcusable absence” from the debate over the past four years.  Though climate change is indeed an existential threat, the world has yet to adequately respond to it.  Noting that the question of climate change is no longer one for debate, he declared:  “The evidence, the science, is screaming at us.”  Many of the world’s regions most impacted by climate change are also projected to become future conflict hotspots.  Therefore, the issue must feature in all of the Council’s work and reporting.  Emphasizing that President Joseph R. Biden understands that “we do not have a moment to waste”, he cited his new coordinated, whole-of-Government approach which aims to elevate the issue and put the United States on the path to sustainability that can never be reversed by any future President or demagogue.

Addressing climate change will require every country to step up and boost their level of ambition, he said, noting that the world’s largest carbon emitters bear the greatest responsibility.  First and foremost will be the need to reduce the use of coal globally.  “Inaction comes with a far higher price tag than action,” he said, stressing that, not since the industrial revolution has there been such potential to build back better in every part of the globe.  Just by doing nothing, humanity will march forward in what is tantamount to a mutual suicide pact, he warned, spotlighting the importance of the climate summit to be hosted by President Biden in the coming weeks, as well as the Conference of Parties to the UNFCCC to be held in Glasgow later in 2021.  The United States will also work with like-minded countries in the Council, he said, urging Member States to begin treating climate change as the security crisis that it is.

Xie Zhenhua, Special Envoy for Climate Change of China , said that, even as global climate governance enters a new and crucial phase, the spread of COVID-19 poses serious threats to the global response.  Given the differences in historical responsibility and development levels between States, he underscored the principle of common but differentiated responsibility and urged developed nations to lead the way.  In building back after the pandemic, countries should respect nature, protect biodiversity, champion green lifestyles and “avoid old paths of giving without taking” from the Earth.  In that context, he described climate change as a development issue, urging the international community to support developing nations, least developed countries and small island developing States in implementing mitigation and adaptation measures.

“We need to stay committed to multilateralism,” he stressed, underlining the importance of UNFCCC and the Paris Agreement as the main channels for those critical discussions.  Any role to be played by the Security Council on climate change must fall under its purview, he added.  Outlining China’s commitment to fulfilling its responsibilities under the Paris Agreement, he spotlighted its recently announced plan to have national CO 2 emissions peak before 2030 and to achieve carbon neutrality prior to 2060.  He also pointed out that the country’s forest cover has been rising steadily for many years, that it leads the world in green power generation and that it tops the list of clean energy patents registered.

The representative of the Russian Federation agreed that addressing climate change requires a global approach that is coordinated, targeted at reducing emissions and implementing effective adaptation measures, especially through UNFCCC.  Noting that the Council has discussed climate change on several occasions, he said the issue is often presented as a fundamental threat to stability and as a root cause of problems, particularly in Africa, with warnings about the increasing risks of conflict.  While he agreed that climate change can exacerbate conflict, he questioned whether it is the root cause of violence.  “There are serious doubts,” he said.  The connection between climate and conflict can be examined only in certain countries and regions.  Discussing it in the global context is not relevant.  “Not all conflicts are threats to international peace and security,” he explained.  In addition, considering climate as a root cause of security issues distracts from the true root causes, and thus, hinders solutions.  Political and socioeconomic factors, which have a greater influence on conflict risk, cannot be ignored, he said, pointing out that COVID-19 has exacerbated inequalities within and between countries and sparked an uptick in hunger — including in countries that were already in conflict.  He urged donors to address the problem of “green protectionism”, seen in their refusal to exchange technology that would allow others to adapt.   While discussing climate issues in the Council is seen as beneficial, the “real work” of improving coordination of international activities would be better accomplished in the General Assembly, the Economic and Social Council and UNFCC.  Conflicts — in and of themselves — reduce the ability of States to adapt to climate change, he said, explaining that the increased security risks in the Sahel are, in fact, caused by countries pursuing regime change in Libya.

Lazarus McCarthy Chakwera, President of Malawi , speaking for the least developed countries, said building resilience to mitigate the security risks associated with climate change must begin with reflections on COVID-19, as Governments have relegated many other priorities in the quest to fight the virus.  Describing the impact of the nexus between climate change and security is “indiscriminate and consequential”, he said water scarcity, desertification and cyclones all foster competition for resources, and in the process, turn people into climate refugees.  Least developed countries bear the brunt of these phenomena, despite that their emissions are 30 times lower than those of high‑income countries.  Stressing that recovery from the coronavirus must be aligned with efforts to limit global temperature rise to 1.5°C, he pressed developed countries to approach the 2021 UNFCC meeting with more ambition than in years past, as their current commitments to cut emissions remain “woefully inadequate”.  They must fulfil their pledges to provide $100 billion in climate financing annually, answer the call to earmark 50 per cent of financing in the Green Climate Fund for adaptation, especially in least developed countries, and to meaningfully transfer climate‑friendly technologies to help least developed countries accelerate their green development efforts.

Gaston Alphonso Browne, Prime Minister and Minister for Finance and Corporate Governance of Antigua and Barbuda , spoke on behalf of the Alliance of Small Island States, declaring:  “Make no mistake […] climate change’s existential threat to our own survival is not a future consideration, but a current reality.”  For the past 30 years, the Alliance has been the single most consistent advocate on climate, he said, highlighting the often-overlooked threats faced by small island developing States.  He urged the international community to simultaneously plan and operationalize a system to address inevitable loss and damage which uproot peace and security of small island developing States.  Equitable solutions are needed to systematically address difficult issues, such as climate change displacement, including the treatment of climate refugees, and loss of territory. For the past three decades, small island and low-lying States have been sounding the alarm, sending the SOS distress signal.  They are losing their territories, populations, resources and very existence due to climate change.  The Secretary-General recently stated:  “Without nature’s help, we will not thrive or even survive[…] For too long, we have been waging a senseless and suicidal war on nature.”  Sadly, small island developing States continue to be the front line for this war.  “Our appeal for the Council is to take this threat very seriously before it is too late,” he said.

Heiko Maas, Federal Minister for Foreign Affairs of Germany , speaking for the Group of Friends of Climate and Security, said those countries are united by the common belief that climate change is the fundamental challenge of our time.  The poorest and most vulnerable are suffering the most, with entire islands at risk of disappearing.  “We are putting their future, their safety and their well‑being at risk if we don’t act,” he stressed, calling for concerted efforts by the United Nations in making climate change its top priority.  Agreeing with other speakers that the issue has major implications for peace and security, he said it therefore belongs firmly on the Council’s agenda.  In July 2020, the Nauru delegation presented the organ with a plan of action, including calling for the appointment of a Special Envoy on Climate and Security; regular reporting to the Council; climate‑sensitive peacebuilding; and more cooperation with civil society, regional and national actors on climate-related security risks.  Now, it is time for the Council to adopt a strong resolution reflecting each of those points, he said.

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Science News

Abdulhamid Hosbas/Anadolu Agency via Getty Images

Century of Science: Theme

Our climate change crisis

The climate change emergency.

Even in a world increasingly battered by weather extremes, the summer 2021 heat wave in the Pacific Northwest stood out. For several days in late June, cities such as Vancouver, Portland and Seattle baked in record temperatures that killed hundreds of people. On June 29 Lytton, a village in British Columbia, set an all-time heat record for Canada, at 121° Fahrenheit (49.6° Celsius); the next day, the village was incinerated by a wildfire.

Within a week, an international group of scientists had analyzed this extreme heat and concluded it would have been virtually impossible without climate change caused by humans. The planet’s average surface temperature has risen by at least 1.1 degree Celsius since preindustrial levels of 1850–1900 — because people are loading the atmosphere with heat-trapping gases produced during the burning of fossil fuels, such as coal and gas, and from cutting down forests.

A little over 1 degree of warming may not sound like a lot. But it has already been enough to fundamentally transform how energy flows around the planet. The pace of change is accelerating, and the consequences are everywhere. Ice sheets in Greenland and Antarctica are melting, raising sea levels and flooding low-lying island nations and coastal cities. Drought is parching farmlands and the rivers that feed them. Wildfires are raging. Rains are becoming more intense, and weather patterns are shifting .

The roots of understanding this climate emergency trace back more than a century and a half. But it wasn’t until the 1950s that scientists began the detailed measurements of atmospheric carbon dioxide that would prove how much carbon is pouring from human activities. Beginning in the 1960s, researchers began developing comprehensive computer models that now illuminate the severity of the changes ahead.

Global average temperature change, 1850–2021

Long-term climate datasets show that Earth’s average surface temperature (combined land and ocean) has increased by more than 1 degree Celsius since preindustrial times. Temperature change is the difference from the 1850–1900 average.

Today we know that climate change and its consequences are real, and we are responsible. The emissions that people have been putting into the air for centuries — the emissions that made long-distance travel, economic growth and our material lives possible — have put us squarely on a warming trajectory . Only drastic cuts in carbon emissions, backed by collective global will, can make a significant difference.

“What’s happening to the planet is not routine,” says Ralph Keeling, a geochemist at the Scripps Institution of Oceanography in La Jolla, Calif. “We’re in a planetary crisis.” — Alexandra Witze

Tracking a Greenland glacier

The calving front of Greenland’s Helheim Glacier, which flows toward the sea where it crumbles into icebergs, held roughly the same position from the 1970s until 2001 (left, the calving front is to the far right of the image). But by 2005 (right), it had retreated 7.5 kilometers toward its source. 

The first climate scientists

One day in the 1850s, Eunice Newton Foote, an amateur scientist and women’s rights activist living in upstate New York, put two glass jars in sunlight. One contained regular air — a mix of nitrogen, oxygen and other gases including carbon dioxide — while the other contained just CO 2 . Both had thermometers in them. As the sun’s rays beat down, Foote observed that the jar of CO 2 alone heated more quickly, and was slower to cool, than the one containing plain air.

The results prompted Foote to muse on the relationship between CO 2 , the planet and heat. “An atmosphere of that gas would give to our earth a high temperature,” she wrote in an 1856 paper summarizing her findings .

Three years later, working independently and apparently unaware of Foote’s discovery, Irish physicist John Tyndall showed the same basic idea in more detail. With a set of pipes and devices to study the transmission of heat, he found that CO 2 gas, as well as water vapor, absorbed more heat than air alone. He argued that such gases would trap heat in Earth’s atmosphere, much as panes of glass trap heat in a greenhouse, and thus modulate climate. “As a dam built across a river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial rays, produces a local heightening of the temperature at the Earth’s surface,” he wrote in 1862.

Today Tyndall is widely credited with the discovery of how what are now called greenhouse gases heat the planet, earning him a prominent place in the history of climate science. Foote faded into relative obscurity — partly because of her gender, partly because her measurements were less sensitive. Yet their findings helped kick off broader scientific exploration of how the composition of gases in Earth’s atmosphere affects global temperatures.

Carbon floods in

Humans began substantially affecting the atmosphere around the turn of the 19th century, when the Industrial Revolution took off in Britain. Factories burned tons of coal; fueled by fossil fuels, the steam engine revolutionized transportation and other industries. In the decades since, fossil fuels including oil and natural gas have been harnessed to drive a global economy. All these activities belch gases into the air.

Yet Svante Arrhenius, a Swedish physical chemist, wasn’t worried about the Industrial Revolution when he began thinking in the late 1800s about changes in atmospheric CO 2 levels. He was instead curious about ice ages — including whether a decrease in volcanic eruptions, which can put CO 2 into the atmosphere, would lead to a future ice age. Bored and lonely in the wake of a divorce, Arrhenius set himself to months of laborious calculations involving moisture and heat transport in the atmosphere at different zones of latitude. In 1896 he reported that halving the amount of CO 2 in the atmosphere could indeed bring about an ice age — and that doubling CO 2 would raise global temperatures by around 5 to 6 degrees C.

It was a remarkably prescient finding for work that, out of necessity, had simplified Earth’s complex climate system down to just a few variables. Today, estimates for how much the planet will warm through a doubling of CO 2 — a measure known as climate sensitivity — range between 1.5 degrees and 4.5 degrees Celsius. (The range remains broad in part because scientists now incorporate their understanding of many more planetary feedbacks than were recognized in Arrhenius’ day.)  

But Arrhenius’ findings didn’t gain much traction with other scientists at the time. The climate system seemed too large, complex and inert to change in any meaningful way on a timescale that would be relevant to human society. Geologic evidence showed, for instance, that ice ages took thousands of years to start and end. What was there to worry about? And other laboratory experiments — later shown to be flawed — appeared to indicate that changing levels of CO 2 would have little impact on heat absorption in the atmosphere. Most scientists aware of the work came to believe that Arrhenius had been proved wrong.

One researcher, though, thought the idea was worth pursuing. Guy Stewart Callendar, a British engineer and amateur meteorologist, had tallied weather records over time, obsessively enough to determine that average temperatures were increasing at 147 weather stations around the globe. In 1938, in a paper in a Royal Meteorological Society journal , he linked this temperature rise to the burning of fossil fuels. Callendar estimated that fossil fuel burning had put around 150 billion metric tons of CO 2 into the atmosphere since the late 19th century.

Like many of his day, Callendar didn’t see global warming as a problem. Extra CO 2 would surely stimulate plants to grow and allow crops to be farmed in new regions. “In any case the return of the deadly glaciers should be delayed indefinitely,” he wrote. But his work revived discussions tracing back to Tyndall and Arrhenius about how the planetary system responds to changing levels of gases in the atmosphere. And it began steering the conversation toward how human activities might drive those changes.

When World War II broke out the following year, the global conflict redrew the landscape for scientific research. Hugely important wartime technologies, such as radar and the atomic bomb, set the stage for “big science” studies that brought nations together to tackle high-stakes questions of global reach. And that allowed modern climate science to emerge.

The Keeling curve and climate change

One major postwar effort was the International Geophysical Year, an 18-month push in 1957–1958 that involved a wide array of scientific field campaigns including exploration in the Arctic and Antarctica. Climate change wasn’t a high research priority during the IGY, but some scientists in California, led by Roger Revelle of the Scripps Institution of Oceanography in La Jolla, used the funding influx to begin a project they’d long wanted to do. The goal was to measure CO 2 levels at different locations around the world, accurately and consistently.

The job fell to geochemist Charles David Keeling, who put ultraprecise CO 2 monitors in Antarctica and on the Hawaiian volcano of Mauna Loa. Funds soon ran out to maintain the Antarctic record, but the Mauna Loa measurements continued. Thus was born one of the most iconic datasets in all of science — the “Keeling curve,” which tracks the rise of atmospheric CO 2 . When Keeling began his measurements in 1958, CO 2 made up 315 parts per million of the global atmosphere. Within just a few years it became clear that the number was increasing year by year. Because plants take up CO 2 as they grow in spring and summer and release it as they decompose in fall and winter, CO 2 concentrations rose and fell each year in a sawtooth pattern — but superimposed on that pattern was a steady march upward.  

Monthly average CO 2 concentrations at Mauna Loa Observatory

Atmospheric carbon dioxide measurements collected continuously since 1958 at Mauna Loa volcano in Hawaii show the rise due to human activities. The visible sawtooth pattern is due to seasonal plant growth: Plants take up CO 2 in the growing seasons, then release it as they decompose in fall and winter.

“The graph got flashed all over the place — it was just such a striking image,” says Ralph Keeling, who is Charles David Keeling’s son. Over the years, as the curve marched higher, “it had a really important role historically in waking people up to the problem of climate change.” The Keeling curve has been featured in countless earth science textbooks, congressional hearings and in Al Gore’s 2006 documentary on climate change, An Inconvenient Truth . Each year the curve keeps going up: In 2016 it passed 400 ppm of CO 2 in the atmosphere, as measured during its typical annual minimum in September. In 2021, the annual minimum was 413 ppm. (Before the Industrial Revolution, CO 2 levels in the atmosphere had been stable for centuries at around 280 ppm.)

Around the time that Keeling’s measurements were kicking off, Revelle also helped develop an important argument that the CO 2 from human activities was building up in Earth’s atmosphere. In 1957 he and Hans Suess, also at Scripps at the time, published a paper that traced the flow of radioactive carbon through the oceans and the atmosphere. They showed that the oceans were not capable of taking up as much CO 2 as previously thought; the implication was that much of the gas must be going into the atmosphere instead. “Human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future,” Revelle and Suess wrote in the paper. It’s one of the most famous sentences in earth science history.

“Human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.”

Here was the insight underlying modern climate science: Atmosheric CO 2 is increasing, and humans are causing the buildup. Revelle and Suess became the final piece in a puzzle dating back to Svante Arrhenius and John Tyndall.

“I tell my students that to understand the basics of climate change, you need to have the cutting-edge science of the 1860s, the cutting-edge math of the 1890s and the cutting-edge chemistry of the 1950s,” says Joshua Howe, an environmental historian at Reed College in Portland, Ore.

Environmental awareness grows

As this scientific picture began to emerge in the late 1950s, Science News was on the story. A March 1, 1958 article in Science News Letter , “Weather May Be Warming,” described a warm winter month in the Northern Hemisphere. It posits three theories, including that “carbon dioxide poured into the atmosphere by a booming industrial civilization could have caused the increase. By burning up about 100 billion tons of coal and oil since 1900, man himself may be changing the climate.” By 1972, the magazine was reporting on efforts to expand global atmospheric greenhouse gas monitoring beyond Keeling’s work; two years later, the U.S. National Oceanic and Atmospheric Administration launched its own CO 2 monitoring network, now the biggest in the world.

Environmental awareness on other issues grew in the 1960s and 1970s. Rachel Carson catalyzed the modern U.S. environmental movement in 1962 when she published a magazine series and then a book, Silent Spring , condemning the pesticide DDT for its ecological impacts. 1970 saw the celebration of the first Earth Day , in the United States and elsewhere, and in India in 1973 a group of women led a series of widely publicized protests against deforestation. This Chipko movement explicitly linked environmental protection with protecting human communities, and helped seed other environmental movements.

The fragility of global energy supplies was also becoming more obvious through the 1970s. The United States, heavily dependent on other countries for oil imports, entered a gas shortage in 1973–74 when Arab members of the Organization of the Petroleum Exporting Countries cut off oil supplies because of U.S. government support for Israel. The shortage prompted more people to think about the finiteness of natural resources and the possibility of overtaxing the planet. — Alexandra Witze

Climate change evidence piles up

Observational data collected throughout the second half of the 20th century helped researchers gradually build their understanding of how human activities were transforming the planet. “It was a sort of slow accretion of evidence and concern,” says historian Joshua Howe of Reed College.

Environmental records from the past, such as tree rings and ice cores, established that the current changes in climate are unusual compared with the recent past. Yet such paleoclimatology data also showed that climate has changed quickly in the deep past — driven by triggers other than human activity, but with lessons for how abrupt planetary transformations can be.

Ice cores pulled from ice sheets, such as that atop Greenland, offer some of the most telling insights for understanding past climate change. Each year snow falls atop the ice and compresses into a fresh layer of ice representing climate conditions at the time it formed. The abundance of certain forms, or isotopes, of oxygen and hydrogen in the ice allows scientists to calculate the temperature at which it formed, and air bubbles trapped within the ice reveal how much carbon dioxide and other greenhouse gases were in the atmosphere at that time. So drilling down into an ice sheet is like reading the pages of a history book that go back in time the deeper you go.

Scientists began reading these pages in the early 1960s, using ice cores drilled at a U.S. military base in northwest Greenland . Contrary to expectations that past climates were stable, the cores hinted that abrupt climate shifts had happened over the last 100,000 years. By 1979, an international group of researchers was pulling another deep ice core from a second location in Greenland — and it, too, showed that abrupt climate change had occurred in the past. In the late 1980s and early 1990s a pair of European- and U.S.-led drilling projects retrieved even deeper cores from near the top of the ice sheet, pushing the record of past temperatures back a quarter of a million years.

Together with other sources of information, such as sediment cores drilled from the seafloor and molecules preserved in ancient rocks, the ice cores allowed scientists to reconstruct past temperature changes in extraordinary detail. Many of those changes happened alarmingly fast. For instance, the climate in Greenland warmed abruptly more than 20 times in the last 80,000 years, with the changes occurring in a matter of decades. More recently, a cold spell that set in around 13,000 years ago suddenly came to an end around 11,500 years ago — and temperatures in Greenland rose 10 degrees Celsius in a decade.

Evidence for such dramatic climate shifts laid to rest any lingering ideas that global climate change would be slow and unlikely to occur on a timescale that humans should worry about. “It’s an important reminder of how ‘tippy’ things can be,” says Jessica Tierney, a paleoclimatologist at the University of Arizona in Tucson.

More evidence of global change came from Earth-observing satellites, which brought a new planet-wide perspective on global warming beginning in the 1960s. From their viewpoint in the sky, satellites have measured the steady rise in global sea level — currently 3.4 millimeters per year and accelerating, as warming water expands and as ice sheets melt — as well as the rapid decline in ice left floating on the Arctic Ocean each summer at the end of the melt season. Gravity-sensing satellites have ‘weighed’ the Antarctic and Greenlandic ice sheets from above since 2002, reporting that more than 400 billion metric tons of ice are lost each year.

Temperature observations taken at weather stations around the world also confirm that we are living in the hottest years on record. The 10 warmest years since record keeping began in 1880 have all occurred since 2005. And nine of those 10 have come since 2010.

What’s more, extreme weather is hammering the planet more and more frequently. That 2021 heat wave in the Pacific Northwest, for instance, is just a harbinger of what’s to come. — Alexandra Witze

Worrisome predictions from climate models

By the 1960s, there was no denying that the planet was warming. But understanding the consequences of those changes — including the threat to human health and well-being — would require more than observational data. Looking to the future depended on computer simulations: complex calculations of how energy flows through the planetary system. Such models of the climate system have been crucial to developing projections for what we can expect from greenhouse warming.

A first step in building climate models was to connect everyday observations of weather to the concept of forecasting future climate. During World War I, the British mathematician Lewis Fry Richardson imagined tens of thousands of meteorologists working to forecast the weather, each calculating conditions for a small part of the atmosphere but collectively piecing together a global forecast. Richardson published his work in 1922, to reviews that called the idea “of almost quixotic boldness.”

But it wasn’t until after World War II that computational power turned Richardson’s dream into reality. In the wake of the Allied victory, which relied on accurate weather forecasts for everything from planning D-Day to figuring out when and where to drop the atomic bombs, leading U.S. mathematicians acquired funding from the federal government to improve predictions. In 1950 a team led by Jule Charney, a meteorologist at the Institute for Advanced Study in Princeton, N.J., used the ENIAC, the first general-purpose, programmable electronic computer, to produce the first computer-driven regional weather forecast . The forecasting was slow and rudimentary, but it built on Richardson’s ideas of dividing the atmosphere into squares, or cells, and computing the weather for each of those. With the obscure title “Numerical integration of the barotropic vorticity equation,” the paper reporting the results set the stage for decades of climate modeling to follow.

By 1956 Norman Phillips, a member of Charney’s team, had produced the world’s first general circulation model, which captured how energy flows between the oceans, atmosphere and land. Phillips ran the calculations on a computer with just 5 kilobytes of memory, yet it was able to reproduce monthly and seasonal patterns in the lower atmosphere. That meant scientists could begin developing more realistic models of how the planet responds to factors such as increasing levels of greenhouse gases. The field of climate modeling was born.

The work was basic at first, because early computers simply didn’t have much computational power to simulate all aspects of the planetary system. “People thought that it was stupid to try to study this greenhouse-warming issue by three-dimensional model[s], because it cost so much computer time,” meteorologist Syukuro Manabe told physics historian Spencer Weart in a 1989 oral history .

Climate models have predicted how much ice the Ilulissat region of the Greenland ice sheet might lose by 2300 based on different scenarios for greenhouse gas emissions. The models are compared to 2008 (first image). In a best-case scenario, in which emissions peak by mid-century, the speed at which the glacier is sending ice out into the ocean is much lower (second image) than with a worst-case scenario, in which emissions rise at a high rate (third image).

An important breakthrough came in 1967, when Manabe and Richard Wetherald — both at the Geophysical Fluid Dynamics Laboratory in Princeton, a lab born from Charney’s group — published a paper in the Journal of the Atmospheric Sciences that modeled connections between Earth’s surface and atmosphere and calculated how changes in carbon dioxide would affect the planet’s temperature. Manabe and Wetherald were the first to build a computer model that captured the relevant processes that drive climate , and to accurately simulate how the Earth responds to those processes. (Manabe shared the 2021 Nobel Prize in physics for his work on climate modeling; Wetherald died in 2011.)

The rise of climate modeling allowed scientists to more accurately envision the impacts of global warming. In 1979, Charney and other experts met in Woods Hole, Mass., to try to put together a scientific consensus on what increasing levels of CO 2 would mean for the planet. They analyzed climate models from Manabe and from James Hansen of NASA. The resulting “Charney report” concluded that rising CO 2 in the atmosphere would lead to additional and significant climate change. The ocean might take up much of that heat, the scientists wrote — but “it appears that the warming will eventually occur, and the associated regional climatic changes so important to the assessment of socioeconomic consequence may well be significant.”

In the decades since, climate modeling has gotten increasingly sophisticated . Scientists have drawn up a variety of scenarios for how carbon emissions might change in the future, depending on the stringency of emissions cuts. Modelers use those scenarios to project how climate and weather will change around the globe, from hotter croplands in China to melting glaciers in the Himalayas. Climate simulations have also allowed researchers to identify the fingerprints of human impacts on extreme weather that is already happening, by comparing scenarios that include the influence of human activities with those that do not.

And as climate science firmed up and the most dramatic consequences became clear, the political battles raged. — Alexandra Witze

Climate science meets politics

With the development of climate science tracing back to the early Cold War, perhaps it shouldn’t be a surprise that the science of global warming became enmeshed in broader societal and political battles. A complex stew of political, national and business interests mired society in debates about the reality of climate change, and what to do about it, decades after the science became clear that humans are fundamentally altering the planet’s atmosphere.

Society has pulled itself together before to deal with global environmental problems, such as the Antarctic ozone hole. In 1974 chemists Mario Molina and F. Sherwood Rowland, both of the University of California, Irvine, reported that chlorofluorocarbon chemicals, used in products such as spray cans and refrigerants, caused a chain of reactions that gnawed away at the atmosphere’s protective ozone layer . The resulting ozone hole, which forms over Antarctica every spring, allows more ultraviolet radiation from the sun to make it through Earth’s atmosphere and reach the surface, where it can cause skin cancer and eye damage.

Governments ultimately worked under the auspices of the United Nations to craft the 1987 Montreal Protocol, which strictly limited the manufacture of chlorofluorocarbons . In the years following, the ozone hole began to heal. But fighting climate change would prove to be far more challenging. Chlorofluorocarbons were a suite of chemicals with relatively limited use and for which replacements could be found without too much trouble. But the greenhouse gases that cause global warming stem from a wide variety of human activities, from energy development to deforestation. And transforming entire energy sectors to reduce or eliminate carbon emissions is much more difficult than replacing a set of industrial chemicals.

In 1980, though, researchers took an important step toward banding together to synthesize the scientific understanding of climate change and bring it to the attention of international policy makers. It started at a small scientific conference in Villach, Austria. There, experts met under the auspices of the World Meteorological Organization, the International Council of Scientific Unions and the United Nations Environment Program to discuss the seriousness of climate change. On the train ride home from the meeting, Swedish meteorologist Bert Bolin talked with other participants about how a broader, deeper and more international analysis was needed. In 1985, a second conference was held at Villach to highlight the urgency, and in 1988, the Intergovernmental Panel on Climate Change, the IPCC, was born. Bolin was its first chairperson.

The IPCC became a highly influential and unique body. It performs no original scientific research; instead, it synthesizes and summarizes the vast literature of climate science for policy makers to consider — primarily through massive reports issued every couple of years. The first IPCC report , in 1990, predicted that the planet’s global mean temperature would rise more quickly in the following century than at any point in the last 10,000 years, due to increasing greenhouse gases in the atmosphere. Successive IPCC reports showed more and more confidence in the link between greenhouse emissions and rising global temperatures — and explored how society might mitigate and adapt to coming changes.

IPCC reports have played a key role in providing scientific information for nations discussing how to stabilize greenhouse gas concentrations. This process started with the Rio Earth Summit in 1992 , which resulted in the U.N. Framework Convention on Climate Change. Annual U.N. meetings to tackle climate change led to the first international commitments to reduce emissions, the Kyoto Protocol of 1997. Under it, developed countries committed to reduce emissions of CO 2 and other greenhouse gases. By 2007 the IPCC declared that the reality of climate warming is “unequivocal ”; the group received the Nobel Peace Prize that year along with Al Gore for their work on climate change.

The IPCC process ensured that policy makers had the best science at hand when they came to the table to discuss cutting emissions. “If you go back and look at the original U.N. framework on climate change, already you see the core of the science represented there,” says Rachel Cleetus, a climate policy expert with the Union of Concerned Scientists in Cambridge, Mass. Of course, nations did not have to abide by that science — and they often didn’t.

Throughout the 2000s and 2010s, international climate meetings discussed less hard-core science and more issues of equity. Countries such as China and India pointed out that they needed energy to develop their economies, and that nations responsible for the bulk of emissions through history, such as the United States, needed to lead the way in cutting greenhouse gases. Meanwhile, residents of some of the most vulnerable nations, such as low-lying islands that are threatened by sea level rise, gained visibility and clout at international negotiating forums. “The issues around equity have always been very uniquely challenging in this collective action problem,” says Cleetus.

By 2015, the world’s nations had made some progress on the emissions cuts laid out in the Kyoto Protocol, but it was still not enough to achieve substantial global reductions. That year, a key U.N. climate conference in Paris produced an international agreement to try to limit global warming to 2 degrees C , and preferably 1.5 degrees C, above preindustrial levels.

Every country has its own approach to the challenge of addressing climate change. In the United States, which gets approximately 80 percent of its energy from fossil fuels, sophisticated efforts to downplay and critique the science led to major delays in climate action. For decades U.S. fossil fuel companies such as ExxonMobil worked to influence politicians to take as little action on emissions reductions as possible. Working with a small group of influential scientists, this well-funded, well-orchestrated campaign took many of its tactics from earlier tobacco-industry efforts to cast doubt on the links between smoking and cancer, as historians Naomi Oreskes and Erik Conway documented in their book Merchants of Doubt.

Perhaps the peak of U.S. climate denialism came in the late 1980s and into the 1990s — roughly a century after Swedish physical chemist Svante Arrhenius laid out the consequences of putting too much carbon dioxide into the atmosphere. In 1988 NASA scientist James Hansen testified to lawmakers about the consequences of global warming. “It is already happening now,” Hansen said, summarizing what scientists had long known.

The high-profile nature of Hansen’s testimony, combined with his NASA expertise, vaulted global warming into the public eye in the United States like never before. “It really hit home with a public who could understand that there are reasons that Venus is hot and Mars is cold,” says Joshua Howe, a historian at Reed College. “And that if you use that same reasoning, we have some concerns about what is happening here on Earth.” But Hansen also kicked off a series of bitter public battles about the reality of human-caused climate change that raged for years.        

One common approach of climate skeptics was to attack the environmental data and models that underlie climate science. In 1998, scientist Michael Mann, then at the University of Massachusetts–Amherst, and colleagues published a detailed temperature record that formed the basis of what came to be known as the “hockey stick” graph, so named because the chart showed a sharp rise in temperatures (the hockey blade) at the end of a long, much flatter period (the hockey stick). Skeptics soon demanded the data and software processing tools Mann used to create the graph. Bloggers and self-proclaimed citizen scientists created a cottage industry of questioning new climate science papers under the guise of “audits.” In 2009 hackers broke into a server at the University of East Anglia, a leading climate-research hub in Norwich, England, and released more than 1,000 e-mails between climate scientists. This “Climategate” scandal purported to reveal misconduct on the part of the researchers, but several reviews largely exonerated the scientists.  

The graph that launched climate skeptic attacks

This famous graph, produced by scientist Michael Mann and colleagues, and then reproduced in a 2001 report by the Intergovernmental Panel on Climate Change, dramatically captures temperature change over time. Climate change skeptics made it the center of an all-out attack on climate science.

Such tactics undoubtedly succeeded in feeding politicians’ delay on climate action in the United States, most of it from Republicans. President George W. Bush withdrew the country from the Kyoto Protocol in 2001 ; Donald Trump similarly rejected the Paris accord in 2017 . As late as 2015, the chair of the Senate’s environment committee, James Inhofe of Oklahoma, brought a snowball into Congress on a cold winter’s day in order to continue his argument that human-caused global warming is a “hoax.” In Australia, a similar mix of right-wing denialism and fossil fuel interests has kept climate change commitments in flux, as prime ministers are voted in and out over fierce debates about how the nation should act on climate.

Yet other nations have moved forward. Some European countries such as Germany aggressively pursued renewable energies, such as wind and solar, while activists such as the Swedish teenager Greta Thunberg — the vanguard of a youth-action movement — pressured their governments for more.

In recent years the developing economies of China and India have taken center stage in discussions about climate action. Both nations argue that they must be allowed extra time to wean themselves off fossil fuels in order to continue economic growth. They note that historically speaking, the United States is the largest total emitter of carbon by far.

Total carbon dioxide emissions by country, 1850–2021

These 20 nations have emitted the largest cumulative amounts of carbon dioxide since 1850. Emissions are shown in in billions of metric tons and are broken down into subtotals from fossil fuel use and cement manufacturing (blue) as well as from land use and forestry (green).

China, whose annual CO 2 emissions surpassed those of the United States in 2006, declared several moderate steps in 2021 to reduce emissions, including that it would stop building coal-burning power plants overseas. India announced it would aim for net-zero emissions by 2070, the first time it has set a date for this goal.

Yet such pledges continue to be criticized. At the 2021 U.N. Climate Change Conference in Glasgow, Scotland, India was globally criticized for not committing to a complete phaseout of coal — although the two top emitters, China and the United States, have not themselves committed to phasing out coal. “There is no equity in this,” says Aayushi Awasthy, an energy economist at the University of East Anglia. — Alexandra Witze

Facing a warmer future

Climate change creeps up gradually on society, except when it doesn’t. The slow increase in sea level, for instance, causes waters to lap incrementally higher at shorelines year after year. But when a big storm comes along — which may be happening more frequently due to climate change — the consequences become much more obvious. Storm surge rapidly swamps communities and wreaks disproportionate havoc. That’s why New York City installed floodgates in its subway and tunnel system in the wake of 2012’s Superstorm Sandy , and why the Pacific island nation of Tuvalu has asked Australia and New Zealand to be prepared to take in refugees fleeing from rising sea levels.

The list of climate impacts goes on and on — and in many cases, changes are coming faster than scientists had envisioned a few decades ago. The oceans are becoming more acidic as they absorb carbon dioxide, harming tiny marine organisms that build protective calcium carbonate shells and are the base of the marine food web. Warmer waters are bleaching coral reefs. Higher temperatures are driving animal and plant species into areas in which they previously did not live, increasing the risk of extinction for many. “It’s no longer about impacts in the future,” says Rachel Cleetus, a climate policy expert at the Union of Concerned Scientists. “It’s about what’s happening in the U.S. here and now, and around the world.”

No place on the planet is unaffected. In many areas, higher temperatures have led to major droughts, which dry out vegetation and provide additional fuel for wildfires such as those that have devastated Australia , the Mediterranean and western North America in recent years. The Colorado River , the source of water for tens of millions of people in the western United States , came under a water-shortage alert in 2021 for the first time in history.

Then there’s the Arctic, where temperatures are rising at more than twice the global average and communities are at the forefront of change. Permafrost is thawing, destabilizing buildings, pipelines and roads. Caribou and reindeer herders worry about the increased risk of parasites to the health of their animals. With less sea ice available to buffer the coast from storm erosion, the Inupiat village of Shishmaref, Alaska, risks crumbling into the sea. It will need to move from its sand-barrier island to the mainland .

“We know these changes are happening and that the Titanic is sinking,” says Louise Farquharson, a geomorphologist at the University of Alaska in Fairbanks who monitors permafrost and coastal change around Alaska. Like many Arctic scientists, she is working with Indigenous communities to understand the shifts they’re experiencing and what can be done when buildings start to slump and water supplies start to drain away. “A big part is just listening to community members and understanding what they’re seeing change,” she says.

All around the planet, those who depend on intact ecosystems for their survival face the greatest threat from climate change. And those with the least resources to adapt to climate change are the ones who feel it first .

“We are going to warm,” says Claudia Tebaldi, a climate scientist at Lawrence Berkeley National Laboratory in California. “There is no question about it. The only thing that we can hope to do is to warm a little more slowly.”

That’s one reason why the IPCC report released in 2021 focuses on anticipated levels of global warming. There is a big difference between the planet warming 1.5 degrees versus 2 degrees or 2.5 degrees. Consider that we are now at least 1.1 degrees above preindustrial levels of CO 2 and are already seeing dramatic shifts in climate. Given that, keeping further global temperature increases as low as possible will make a big difference in the climate impacts the planet faces. “With every fraction of a degree of warming, everything gets a little more intense,” says paleoclimatologist Jessica Tierney. “There’s no more time to beat around the bush.”

Historical and projected global temperature change

Various scenarios for how greenhouse gas emissions might change going forward help scientists predict future climate change. This graph shows the simulated historical temperature trend along with future projections of global surface temperature based on five scenarios from the Intergovernmental Panel on Climate Change. Temperature change is the difference from the 1850–1900 average.

The future rests on how much nations are willing to commit to cutting emissions and whether they will stick to those commitments. It’s a geopolitical balancing act the likes of which the world has never seen.

Science can and must play a role going forward. Improved climate models will illuminate what changes are expected at the regional scale, helping officials prepare. Governments and industry have crucial parts to play as well. They can invest in technologies, such as carbon sequestration, to help decarbonize the economy and shift society toward more renewable sources of energy. “We can solve these problems — most of the tools are already there,” says Cascade Tuholske, a geographer at Columbia University. “We just have to do it.”

Huge questions remain. Do voters have the will to demand significant energy transitions from their governments? How can business and military leaders play a bigger role in driving climate action? What should be the role of low-carbon energy sources that come with downsides, such as nuclear energy ? How can developing nations achieve a better standard of living for their people while not becoming big greenhouse gas emitters? How can we keep the most vulnerable from being disproportionately harmed during extreme events, and incorporate environmental and social justice into our future?

These questions become more pressing each year, as CO 2 accumulates in our atmosphere. The planet is now at higher levels of CO 2 than at any time in the last 3 million years. Yet Ralph Keeling, keeper of the iconic Mauna Loa record tracking the rise in atmospheric CO 2 , is already optimistically thinking about how scientists would be able to detect a slowdown, should the world actually start cutting emissions by a few percent per year. “That’s what the policy makers want to see — that there’s been some large-scale impact of what they did,” he says.

At the 2021 U.N. climate meeting in Glasgow diplomats from around the world agreed to work more urgently to shift away from using fossil fuels. They did not, however, adopt targets strict enough to keep the world below a warming of 1.5 degrees Celsius. It’s been well over a century since Svante Arrhenius recognized the consequences of putting extra carbon dioxide into the atmosphere, and yet world leaders have yet to pull together to avoid the most dangerous consequences of climate change.

Time is running out. — Alexandra Witze

Climate change facts

We know that climate change and its consequences are real, and we are responsible. Here’s what the science tells us.

How much has the planet warmed over the past century?

The planet’s average surface temperature has risen by at least 1.1 degree Celsius since preindustrial levels of 1850–1900.

What is causing climate change?

People are loading the atmosphere with carbon dioxide and other heat-trapping gases produced during the burning of fossil fuels, such as coal and gas, and cutting down forests.

What are some of the effects of climate change?

Ice sheets in Greenland and Antarctica are melting, raising sea levels and flooding low-lying island nations and coastal cities. Drought is parching farmlands and the rivers that feed them. Wildfires are raging. Rains are becoming more intense, and weather patterns are shifting.

What is the greenhouse effect?

In the 19th century, Irish physicist John Tyndall found that carbon dioxide gas, as well as water vapor, absorbed more heat than air alone. He argued that such gases would trap heat in Earth’s atmosphere, much as panes of glass trap heat in a greenhouse, and thus modulate climate.

What is the Keeling curve?

One of the most iconic datasets in all of science, the Keeling curve tracks the rise of atmospheric CO 2 . When geochemist Charles David Keeling began his measurements in 1958 on the Hawaiian volcano of Mauna Loa, CO 2 made up 315 parts per million of the global atmosphere. Each year the curve keeps going up: In 2016 it passed 400 ppm of CO 2 in the atmosphere, as measured during its typical annual minimum in September. In 2021, the annual minimum was 413 ppm.

Does it get hotter every year?

Average global temperatures fluctuate from year to year, but temperature observations taken at weather stations around the world confirm that we are living in the hottest years on record. The 10 warmest years since record keeping began in 1880 have all occurred since 2005. And nine of those 10 have come since 2010.

What countries emit the most carbon dioxide?

The United States has been the largest total emitter of carbon dioxide by far, followed by China and Russia. China’s annual CO 2 emissions surpassed those of the United States in 2006.

What places are impacted by climate change?

No place on the planet is unaffected. Higher temperatures have led to major droughts, providing fuel for wildfires such as those that have devastated Australia , the Mediterranean and western North America in recent years. The Colorado River came under a water-shortage alert in 2021 for the first time in history. In the Arctic, where temperatures are rising at more than twice the global average, permafrost is thawing, destabilizing buildings, pipelines and roads. With less sea ice available to buffer the coast from storm erosion, the Inupiat village of Shishmaref, Alaska, risks crumbling into the sea. All around the planet, those who depend on intact ecosystems for their survival face the greatest threat from climate change. And those with the least resources to adapt to climate change are the ones who feel it first .

Editor’s note: This story was published March 10, 2022.

British mathematician Lewis Fry Richardson (shown at center) proposes forecasting the weather by piecing together the calculations of tens of thousands of meteorologists working on small parts of the atmosphere.

Geochemist Charles David Keeling (shown in 1988) begins tracking the rise in atmospheric carbon dioxide at Mauna Loa in Hawaii. The record, which continues through today, has become one of the most iconic datasets in all of science.

Rachel Carson (shown) publishes the book Silent Spring , raising alarm over the ecological impacts of the pesticide DDT. The book helps catalyze the modern U.S. environmental movement.

The first Earth Day, organized by U.S. senator Gaylord Nelson and graduate student Denis Hayes, is celebrated.

The first Landsat satellite launched (shown), opening the door to continuous monitoring of Earth and its features from above.

A powerful eruption from the Philippines’ Mount Pinatubo (shown) ejects millions of tons of sulfur dioxide into the stratosphere, temporarily cooling the planet.  

World leaders gathered (shown) at the United Nations Conference on Environment and Development in Rio de Janeiro to address how to pursue economic development while also protecting the Earth. The meeting resulted in an international convention on climate change.

Activist Greta Thunberg initiates the “School Strike for Climate” movement by protesting outside the Swedish parliament. Soon, students around the world join a growing movement demanding action on climate change . (Activists at the 2021 U.N. Climate Change Conference are shown.)

From the archive

Climate change foreseen.

In an early mention of climate change in Science News-Letter , the predecessor of Science News , British meteorologist C.E.P. Brooks warns that present warming trends could lead to “important economic and political effects.”

IGY Brings Many Discoveries

Science News Letter lists the Top 8 accomplishments of the International Geophysical Year.

Chilling possibilities

Science News explores the tentative idea that global temperatures are cooling and that a new ice age could be imminent, which is later shown to be inaccurate.

Long Hot Future: Warmer Earth Appears Inevitable

“The planet earth will be a warmer place in the 21st century, and there is no realistic strategy that can prevent the change,” Science News reports.

Ozone and Global Warming: What to Do?

Policy makers discuss how to solve the dual problems of ozone depletion and global warming.

Looking for Mr. Greenhouse

Science writer Richard Monastersky reports on scientists’ efforts to evaluate how to connect increasing greenhouse gases and a warming climate.

World Climate Panel Charts Path for Action

The Intergovernmental Panel on Climate Change reports that “the fingerprint of man in the past temperature record” is now apparent.

Animals on the Move

A warming climate means shifting ranges and ecosystem disruptions for a lot of species, Nancy Ross-Flanigan reports.

Changing climate: 10 years after ‘An Inconvenient Truth’

A decade after former vice president Al Gore releases the documentary film An Inconvenient Truth , Science News looks back at how climate science has advanced.

With nowhere to hide from rising seas, Boston prepares for a wetter future

Mary Caperton Morton reports for Science News on how Boston is taking action to prepare for rising seas.

The new UN climate change report shows there’s no time for denial or delay

Earth & climate writer Carolyn Gramling covers the sixth assessment report from the Intergovernmental Panel on Climate Change, which documents how climate change is already affecting every region on Earth.

Climate change disinformation is evolving. So are efforts to fight back

Researchers are testing games and other ways to help people recognize climate change denial.

Extreme weather in 2022 showed the global impact of climate change

Heat waves, floods, wildfires and drought around the world were exacerbated by Earth’s changing climate.

It’s possible to reach net-zero carbon emissions. Here’s how

Cutting carbon dioxide emissions to curb climate change and reach net zero is possible but not easy.

The last 12 months were the hottest on record

The planet’s average temperature was about 1.3 degrees Celsius higher than the 1850–1900 average, a new report finds.

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News from the Columbia Climate School

Beyond Climate: The Crisis of Environmental Sustainability

Steven Cohen

Last week and this week many of us are correctly focused on the existential threat of climate change but we must not lose sight of the other deep problems of environmental sustainability that also require action. The good news about climate change is we know a great deal about what causes it and how to stop it. We have much more to learn to fully understand this critical problem, but climate science is more advanced than many other areas of environmental science. The economic and policy issue of climate change is caused by the intense need for energy in the developed and developing world and the huge investment made globally in fossil fuels. Decarbonization will require skill, ingenuity and leadership, and we’ll see how much of that is present in New York when the U.N. gets to work on climate this week.

Some of the other environmental problems we face still require basic research to fully understand, and even when we know the cause of a problem, we may not know how to solve it. One example of such a problem is declining bird populations, an issue that Carl Zimmer covered in last week’s New York Times .  According to Zimmer:

“ The skies are emptying out. The number of birds in the United States and Canada has fallen by 29 percent since 1970 , scientists reported on Thursday. There are 2.9 billion fewer birds taking wing now than there were 50 years ago. The analysis, published in the journal Science, is the most exhaustive and ambitious attempt yet to learn what is happening to avian populations. The results have shocked researchers and conservation organizations… There are likely many causes, the most important of which include habitat loss and wider use of pesticides. ‘Silent Spring,’ Rachel Carson’s prophetic book in 1962 about the harms caused by pesticides, takes its title from the unnatural quiet settling on a world that has lost its birds: ‘On the mornings that had once throbbed with the dawn chorus of robins, catbirds, doves, jays, wrens, and scores of other bird voices, there was now no sound.’ ”

The loss of birds and threats to many forms of life are an increasingly accepted part of our modern world. Fires in the Amazon are destroying critical and poorly understood ecosystems, plastics in our ocean are destroying various forms of sea life, lead in our water supply is impairing human health and toxics in our waste stream are finding their way into our food supply. The complex and interconnected web of life that makes human life possible, happy and healthy is under deep threat by the technology that also makes human life rewarding, interesting, happy and healthy. In many cases, we do not fully understand the threat and we desperately need additional scientific research, observation, theory and knowledge. If we are to sustainably manage our planet, we need to invest significant additional resources in the science of ecology and environment.

With most of the world’s population in cities, some people may be tempted to ignore these threats to our biosphere and to the ecosystems that comprise it. Some may think we can somehow transcend and ignore nature. But we cannot: Despite the wonders of our technology and the ingenuity that creates it, we humans remain organic, living creatures. We rely on the planet for the food and water that sustains us, and if that food and water is poisoned, we can get sick and die.

Technology provides us with the ability to live the wondrous lives that many of us live, but if the impact of that technology on our planet is ignored, the planet and its inhabitants such as birds and humans can be harmed. The technology that creates harm can also be used to reduce that harm. We can reduce pollution and if we get sick, variants of the technologies that make us sick can also be used to diagnose and treat our illnesses. Think of radioactive materials used in imaging and the chemicals used in chemotherapy. Technology both creates and solves problems. But to successfully apply technology to our problems we need to understand these problems and we need science and engineering knowledge to solve them.

This places a heavy burden on scientists and engineers. This burden is made worse by public officials who are scientifically illiterate and by business people who place profit above the planet’s well-being. In the case of climate science, opponents of greenhouse gas regulation have tried to delegitimize the science. We saw this before with tobacco and cancer. The strategy seems to be to attack the science and reality will somehow go away. Scientists then find themselves defending their work against attacks that are not rooted in science. Many environmental scientists are amateurs at politics and their advocacy can range from naive to extreme. They are experts at science and can defend their work before careful and reasoned academic critiques, but they don’t quite know what to do with the attacks rooted in interest group politics and financial self-interest.

Political interference in scientific research and analysis attempts to replace fact and reason with ideology and bias. This takes us in the opposite direction of the places we need to go. We need ever more sophisticated observations, analyses and models to understand the impact of human activity on the planet. We need to carefully and thoughtfully understand the impacts of our actions and then just as carefully frame approaches to mitigate the damage we have created. Once we develop methods and mechanisms that reduce environmental damage, we need a political process that can scale up these solutions and either through markets, regulation, subsidy or infrastructure, implement and operate these solutions.

Zimmer’s New York Times piece last week demonstrates the power of scientific knowledge and the success it can lead to. As Zimmer observes:

“ The researchers found some positive signs. Bald eagles are thriving, for example, and falcon populations have grown by 33 percent. Waterfowl are on the upswing. For the most part, there’s little mystery about how these happy exceptions came to be. Many recovering bird species were nearly wiped out in the last century by pesticides, hunting and other pressures. Conservation measures allowed them to bounce back. ”

The conservation methods require that our use of land be regulated and that critical habitats be left in their natural states. This can be accomplished by concentrating our urban development and by more efficient use of land for farming. The article notes that if we made skyscraper windows easier for birds to see they might avoid flying into them and could survive. All of this requires that we pay attention to what we do when we make use of the planet and that we adopt an environmental ethic of doing the least possible harm. I am not arguing against economic development, but for a more thoughtful version of it that makes conscious rather than unthinking trade-off decisions when we impact the environment.

Climate change, toxic contamination of the land, ecosystem destruction, air pollution and water pollution are all forms of environmental degradation that we need to learn more about and act to reduce. Each is important. If we decarbonize our economy and stop global warming, but destroy our land, air and water and wipe out the forms of life we depend on, we may find that some of the damage we’ve done will be irreversible. Environmental sustainability requires that we stop global warming, but we must move beyond climate change and address the other critical challenges confronting the planet.

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Columbia Climate School has once again been selected as university partner for Climate Week NYC, an annual convening of climate leaders to drive the transition, speed up progress and champion change. Join us for events and follow our coverage .

Basically, I have noticed that individuals without a background of college level physics, chemistry, biochemistry and/or geology find global climate change is fundamentally unreal for them. Trouble is, the average person on the street does not want to discuss global climate change or extreme recurrent weather events. One cannot put a political spin on the basic laws of physics or chemistry. Last spring when researchers in the Arctic found Nitrous Oxide levels in the atmosphere ( due to melting permafrost ) higher than any previous observation, I felt that a potential tipping point had been breached. Nitrous Oxide has the heat capturing ability that is 300 times that of Carbon Dioxide and stays in the atmosphere for 114 years. This may accelerate the loss of sea and land ice. A concern might be the surface stratification of frigid fresh water over warmer salt water in the North Atlantic resulting in a significant slow down of the AMOC, Atlantic Meridional Overturning Circulation. I don’t believe this would bring about a (regional) little ice age, but it might contribute to the challenges society will have to address in regards as to food security. The food on our personal menu will likely have to be grown in our own backyard or within a few miles. I am afraid that people will carry on with “business as usual” because their goals are comfort and convenience. There may be an unspoken entitlement mindset, I don’t know. Suffering becomes more and more likely as mitigating global climate change is placed on the back burner as individuals in Washington DC attempt to achieve eternal economic glory to the detriment of us all. There’s a saying in Japan that should be in every coastal community household and every inland flood plain, “Nothing under heaven is more pliable than water, yet when amassed, nothing on earth can withstand its force.” How many disasters will it take to bring about an understanding and appreciation of our global climate crisis?

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Covid-19, climate change, and the environment: a sustainable, inclusive, and resilient global recovery

Read our latest coverage of the climate emergency.

• Related content
• Peer review
• Nicholas Stern ,
• IG Patel , professor of economics and government and chair ,
• Bob Ward , policy and communications director
• Grantham Research Institute on Climate Change and the Environment, London School of Economics and Political Science, UK
• r.e.ward{at}lse.ac.uk

We are at a critical moment in history, facing growing crises in climate change, biodiversity, and environmental degradation—as well as covid-19. But we also have an enormous opportunity to transform the global economy and usher in an era of greater wellbeing and prosperity, write Nick Stern and Bob Ward

The covid-19 pandemic has shown how vulnerable and exposed the world is to global threats. The effects of the disease and the measures that have been taken to control it have had serious consequences for lives and livelihoods. In addition to the tragic toll of illness and death, economies have been hit hard, particularly in developing countries.

Continuing to tackle the disease must be the priority, particularly by ensuring access to vaccines and treatments in all countries. Rich countries have a critical responsibility not just to safeguard their own populations but to support the distribution of vaccines to developing countries.

Every country will remain potentially exposed and vulnerable to the SARS-CoV-2 virus as long as it is able to spread rapidly through unvaccinated populations in any part of the world. Common humanity and self-interest point in the same direction.

Governments have tried to limit and reverse the economic damage through rescue and recovery packages. The rescue efforts have understandably focused on protecting existing jobs and companies, but recovery offers the chance to accelerate the transition towards a more inclusive, sustainable, and resilient form of economic development and growth.

A report prepared at the request of the British prime minister, Boris Johnson, for the G7 Leaders’ Summit in Carbis Bay, Cornwall, in June 2021 laid out the case for an investment led recovery from the pandemic. 1 It pointed out that an increase in annual investment of $1tn (£0.7tn; €0.9tn), equivalent to 2% of the collective national output, across the G7 countries over the coming decade and beyond would drive strong growth out of the economic difficulties arising from the pandemic and from the relatively low levels of investment, particularly since the financial crisis in 2008-9, which have been a major cause of sluggish growth in many rich countries over the past decade.

Most of this increase in investment will be made by the private sector, but governments also need to lead by example through their spending programmes both to kickstart growth and play their parts in crucial infrastructure investment, particularly in zero carbon and climate resilient energy, transport, and buildings.

The rich countries should also work to support investment in developing countries to foster sustainable, resilient, and inclusive development and growth. Most global investment in the next two decades will be in emerging markets and developing countries, and the nature of that investment will shape the future for us all in terms of wellbeing and its sustainability.

These investments in both developed and developing countries should aim both to reduce greenhouse gas emissions and to improve resilience against the effects of climate change that cannot now be avoided. Many relevant investments spur development, reduce emissions, and strengthen resilience. There are examples across all sectors: protecting and restoring mangroves; restoring degraded land; expanding and protecting forests; improving public transport; installing decentralised solar energy systems; and constructing and retrofitting buildings to make them more efficient and resilient. All of these can boost economic development, climate change mitigation, and adaptation.

Central to these changes will be extra finance, much of it concessional, from the national and multilateral development banks. This will be crucial to reducing and managing risk for both private and public investment. The scale of the challenge implies that its scale must be expanded.

Growing effects of climate change

The growing consequences of climate change have been all too visible across the world this year with severe heatwaves, floods, wildfires, and tropical cyclones. A new assessment of the science by the Intergovernmental Panel on Climate Change (IPCC), published in August 2021, concluded that there is now a clear link between rising greenhouse gas concentrations in the atmosphere and increases in the frequency and intensity of extreme weather events. 2 It states: “Climate change is already affecting every inhabited region across the globe, with human influence contributing to many observed changes in weather and climate extremes.”

Although the IPCC’s review of the effects of climate change on people and wildlife is not due to be published until next year, losses are clearly mounting around the world. One of the great injustices of climate change is that the poorest people around the world are often most exposed and vulnerable to the effects, even though they are least responsible for the driving cause: the rise in concentrations of carbon dioxide and other greenhouse gases in the atmosphere.

The most recent Human Development Report, 3 published by the United Nations Development Programme in December 2020, pointed out that climate change has played a large role in reducing average incomes, particularly in low income countries, increasing the number of people experiencing hunger and expanding the number of people affected by climate and weather disasters.

Climate change has been making it more difficult to achieve many of the United Nations Sustainable Development Goals (SDGs), even before the pandemic. In his 2021 annual progress report on the SDGs, 4 the United Nations secretary general, António Guterres, said: “The pandemic related economic downturn has pushed between 119 and 124 million more people into extreme poverty in 2020, further compounding challenges to poverty eradication such as conflict, climate change, and natural disasters.”

The mounting damage from climate change is clearly harming efforts to overcome poverty and raise living standards, particularly in developing countries. Global mean surface temperature is already more than 1°C above its pre-industrial level. A special report by the IPCC in October 2018 provided a detailed review of the evidence about the risks of warming exceeding 1.5°C. 5 There is a growing consensus that those risks pose an unacceptable threat.

The IPCC report concluded that, to prevent warming exceeding 1.5°C by the end of the century, greenhouse gas emissions would need to be cut sharply over the coming decades, with net carbon dioxide emissions reduced to zero by 2050—this means that any residual emissions from human activities would need to be compensated by equivalent removals from the atmosphere by planting more vegetation or through other artificial methods involving carbon capture, use, and storage. Many countries have now pledged to reach net zero annual emissions of greenhouse gases by 2050.

New form of economic development and growth

Greater understanding of the urgency required to cut emissions has been accompanied by mounting evidence that it does not mean sacrificing economic development and growth. Annual emissions by the United Kingdom, for example, fell by 43.8% between 1990 and 2019, 6 whereas its gross domestic product rose by 78% over the same period. 7 This is a critically important insight, particularly for developing countries that understandably view economic growth as essential to improving the lives of their citizens. The increase in economic activity is usually accompanied by more jobs, higher incomes, and less hunger, as well as potentially higher tax revenues for governments to invest in public services, including health and education.

Some people argue that greenhouse gas emissions can only be eliminated by killing economic growth. But this is analytically incorrect. There is nothing inherent about economic growth that requires emissions. Energy can be generated from sources other than fossil fuels, which are the main driver of emissions. Furthermore, commitment to the new path for economic development and growth is already generating rapid innovation and cost reduction for most countries. Round-the-clock renewable electricity is now cheaper than fossil fuel electricity in many places, for example. Electric vehicles are more efficient than those driven by internal combustion engines. Resource efficiency (including the circular economy) improves productivity. And progress is rapid.

As countries emerge from the pandemic, investments in the rapid transition away from fossil fuels towards cleaner sources of energy will have multiple economic benefits. It will, for example, drastically reduce the number of deaths from air pollution, which kills more than seven million people worldwide every year, according to the World Health Organization, 8 and knocks several percentage points off economic output, 9 particularly in countries like China and India.

Investments in sustainable infrastructure, such as renewable energy and electric trains, can improve the economic competitiveness of countries and transform cities into more attractive places where people can live, move, and breathe more easily. Infrastructure that is not sustainable has the opposite effect—creating more pollution, waste, and congestion.

An investment led recovery that accelerates the transformation to sustainable, inclusive, and resilient economic development and growth will not only avoid the worst potential consequences of climate change, biodiversity loss, and environmental degradation, but will also create meaningful job opportunities and improve the lives of people around the world. A new form of clean, sustainable, efficient and inclusive development and growth is now in our hands. It will involve strong investment and some dislocation. It is important that the transition is, and is seen to be, just. All this will require strong commitment and leadership. But if offers us a much better future.

Biographies

Nick Stern is a cross bench member of the UK House of Lords. He has been president of the British Academy, the Royal Economic Society, and the European Economic Association. He was head of the UK Government Economic Service from 2003 to 2007 and head of the Stern Review on the Economics of Climate Change , published in 2006. He was chief economist of the European Bank for Reconstruction and Development between 1994 and 1999, and chief economist and senior vice president at the World Bank between 2000 and 2003.

Robert Ward is deputy chair of the London Climate Change Partnership and a fellow of the Geological Society, the Royal Geographical Society, and the Energy Institute. He was previously director of public policy at Risk Management Solutions between 2006 and 2008, and senior manager for policy communication at the Royal Society between 1999 and 2006. He has also worked as a freelance science journalist

Commissioned, not externally peer reviewed.

Competing interests: We have read and understood BMJ policy on declaration of interests and declare the following: NS oversaw the preparation of the G7 report by the Grantham Research Institute on Climate Change and the Environment, which he has chaired since its foundation in 2008, and RW, who has been policy and communications director at the institute since its foundation, was one of the writing team.

This article is made freely available for use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.

• ↵ Stern N. G7 leadership for sustainable, resilient, and inclusive economic recovery and growth: An independent report requested by the UK Prime Minister for the G7. London: Grantham Research Institute on Climate Change and the Environment. June 2021. https://www.lse.ac.uk/granthaminstitute/publication/g7-leadership-for-sustainable-resilient-and-inclusive-economic-recovery-and-growth/ .
• ↵ Intergovernmental Panel on Climate Change. Climate change 2021: the physical science basis. 2021. https://www.ipcc.ch/report/ar6/wg1/#FullReport
• ↵ United Nations Development Programme. Human development report 2020. 2020. http://hdr.undp.org/en/2020-report
• ↵ United Nations Secretary-General. Progress towards the Sustainable Development Goals: report of the secretary-general. 30 April 2021. https://unstats.un.org/sdgs/files/report/2021/secretary-general-sdg-report-2021--EN.pdf
• ↵ Intergovernmental Panel on Climate Change. Global warming of 1.5°C: 2018. https://www.ipcc.ch/sr15/
• ↵ Department for Business, Energy, and Industrial Strategy. 2019 UK greenhouse gas emissions, final figures. 2021. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/957887/2019_Final_greenhouse_gas_emissions_statistical_release.pdf
• ↵ Office for National Statistics. Gross domestic product: chained volume measures: seasonally adjusted £m. 2021. https://www.ons.gov.uk/economy/grossdomesticproductgdp/timeseries/abmi/pn2
• ↵ World Health Organization. Air pollution. 2021. https://www.who.int/health-topics/air-pollution#tab=tab_1
• ↵ World Bank, Institute for Health Metrics and Evaluation. The cost of air pollution: strengthening the economic case for action. 2016. https://documents1.worldbank.org/curated/en/781521473177013155/pdf/108141-REVISED-Cost-of-PollutionWebCORRECTEDfile.pdf

SDGs will address ‘three planetary crises’ harming life on Earth 

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The “three planetary crises” of climate change, biodiversity loss and pollution are reinforcing each other and driving further damage to the environment and to our health, the UN Environment Programme (UNEP) said on Tuesday. 

Executive Director Inger Andersen told an online discussion that the “significant and pathbreaking” information contained in the UN agency’s synthesis report Making Peace With Nature , not only breaks down the science, but also shines a light on “the kind of gearshifts” needed for a steady trajectory forward. 

This includes reaching for the Sustainable Development Goals (SDGs), particularly SDG 12, on sustainable production and consumption, as well as making societies “much more aware of our footprint” on Earth. 

UN Environment Programme April 27, 2021

“It speaks to the urgency of now”, she said. 

Notwithstanding the need to lift people out of poverty, turn the wheels of economy and end world hunger, the report looks at what the earth can provide, and how it must be treated, to remain sustainable.   

Unless improvements are made, the planet is set to lose about a million species, out of an estimated eight million, Ms. Andersen warned. 

Making peace with nature 

During the discussion, report writers Ivar Andreas Baste and Robert Watson , along with scientific advisor Joyeeta Gupta explained how the key findings rested upon a range of assessments, including from UN agencies, intergovernmental environmental bodies and multilateral environmental agreements. 

“Overall about 50 leading experts helped us prepare and guide this synthesis”, Mr. Watson said, adding that the “options for action” within the report are consistent with each other.  

They also outlined that the interconnectivity of the three challenges putting the world’s well-being at risk can be tackled jointly within the SDG framework.  

Planetary emergency 

Since the Stockholm Conference  on the environment over 50 years ago, Mr. Watson pointed out that both the number of environmental issues and their severity have grown, “we clearly know we have a planetary emergency”, he said. 

“Humanity is waging war on nature. This is senseless and suicidal”, Secretary-General António Guterres said in the foreword. “The consequences of our recklessness are already apparent in human suffering, towering economic losses and the accelerating erosion of life on Earth". 

A role for everyone  

The report maintains the need for “ambitious and coordinated action” by governments, businesses and people around the world to prevent and reverse the worst impacts of environmental decline by rapidly transforming energy, water and food systems to support sustainability.  

And while the COVID-19 emergency rightly preoccupies government budgets and political action, the response to this pandemic must ultimately accelerate the economic and social transformations needed to address the planetary emergency.  

“These are not just environmental issues, they are economic, development, security, social, moral and ethical issues”, said Robert Watson. 

Transforming social and economic systems means improving our relationship with nature – understanding its value and putting that value at the heart of decision making, according to the report. 

“By transforming how we view nature, we can recognize its true value. By reflecting this value in policies, plans and economic systems, we can channel investments into activities that restore nature and are rewarded for it”, said the UN chief. 

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Facts about the nature crisis

What you need to know about the nature crisis

We are experiencing a dangerous decline in nature and humans are causing it:

• We are using the equivalent of 1.6 Earths to maintain our current way of life and ecosystems cannot keep up with our demands. (Becoming Generation Restoration, UNEP)
• One million of the world’s estimated 8 million species of plants and animals are threatened with extinction. (IPBES)
• 75 percent of the Earth’s land surface has been significantly altered by human actions, including 85 percent of wetland areas. (IPBES)
• 66 percent of ocean area is impacted by human activities, including from fisheries and pollution. (IPBES)
• Close to 90% of the world’s marine fish stocks are fully exploited, overexploited or depleted. (UNCTAD)
• Our global food system is the primary driver of biodiversity loss with agriculture alone being the identified threat 24,000 of the 28,000 species at risk of extinction. (Chatham House and UNEP)
• Agricultural expansion is said to account for 70% of the projected loss of terrestrial biodiversity. (CBD)

From 7-19 December 2022, countries met in Montreal for  COP15  to strike a landmark agreement to guide global actions on biodiversity.  The Kunming-Montreal Global Biodiversity Framework lays out an ambitious plan that addresses the key drivers of biodiversity loss and puts us on the path to halt and reverse nature loss by 2030. See  UNEP’s COP-15 page  for more information and the latest updates.

What are the impacts of nature loss and degradation

Nature loss has far-reaching consequences. Damaged ecosystems exacerbate climate change, undermine food security and put people and communities at risk. 

• Around 3.2 billion people, or 40 percent of the global population, are adversely affected by land degradation.
• Up to $577 billion in annual global crop production is at risk from pollinator loss.
• 25 percent of global greenhouse gas emissions are generated by land clearing, crop production and fertilization.
• Development is putting animals and humans in closer contact increasing the risk of diseases like COVID-19 to spread. About 60 percent of human infections are estimated to have an animal origin. 
• 100-300 million people are at increased risk of floods and hurricanes because of coastal habitat loss. 
• Declines in nature and biodiversity at current trajectories will undermine progress toward 35 out of 44 of the targets of SDGs related to poverty, hunger, health, water cities, climate, oceans and land.

What do we need to do to halt and reverse nature loss?

We only have until the end of the decade to bend the curve on nature and biodiversity loss. Transformational change is possible if we start now at every level from local to global. Actions that should be taken include:

• The UN Biodiversity Conference (COP 15) in Montreal later this year must culminate in a clearly defined, ambitious Post-2020 Global Biodiversity Framework that is matched by finances and accountability mechanisms to achieve the framework’s targets. Read more about COP 15 .
• Investments in nature-based solutions will need to at least triple by 2030 if the world is to meet its climate change, biodiversity and land degradation targets. Explore UNEP’s State of Finance for Nature report and watch the video.
• Preventing the large-scale collapse of nature will require effective conservation of more of our land, inland waters and oceans, as well as the world delivering on its current commitment to restore at least one billion hectares of degraded land in the next decade. Learn about the UN Decade on Ecosystem Restoration.
• Agriculture has altered the face of the planet more than any other human activity. We need to transform our food systems to become more sustainable and resilient in order to reverse environmental degradation, restore ecosystems and ensure food and nutritional security. Read about food system impacts on nature and biodiversity.
• Governments must assign a financial value on the services that nature provides to people so that environmental action can be prioritized in policy and investment decisions. Read the IPBES new report for how assigning values to nature can help address biodiversity loss.
• Tax structures and subsidies should be reformed to incentivize sustainable production and ensure that environmental degradation no longer pays. This joint FAO-UNDP-UNEP report calls for governments to rethink the way agriculture is subsidized and supported.
• Corporations should put sustainability at the heart of decision making and focus on new sustainable business models to meet society’s needs in ways less impactful on the environment. UNEP’s Global Environment Outlook for Business briefs provide roadmaps that business can follow to address our environmental challenges.
• All financial players should align their business strategies with global and national sustainability goals including the SDGs, the Paris Agreement and the upcoming Biodiversity Framework. Read more about how to catalyze action across the financial system .

Related Sustainable Development Goals

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The climate crisis is a humanitarian crisis

Climate change is a top driver of humanitarian need and human suffering, particularly for the poorest countries. The impacts threaten to deepen already wide inequalities, resulting in consequences felt by the world at large, including instability, violence and displacement.

In a recent speech on humanitarian policy, the UN Under-Secretary-General for Humanitarian Affairs, Mark Lowcock, made the case for action to support the world’s most vulnerable communities, stressing that in 2020, 12 of the 20 countries most vulnerable to climate change had an inter-agency humanitarian appeal. He detailed ongoing and destabilizing fallout from pressures on livelihoods, water, food and health, among other issues.

“Humanitarian aid can only be a temporary band-aid – and a woefully small one at that. We need leaders around the world to take smarter decisions and make smarter investments today,” he said, offering some priorities.

First, scale up adaptation finance to prevent, prepare for, and respond to growing humanitarian crises, and to make communities more resilient.

Second, many countries are getting better at responding to climate-related disasters; the number of people killed by disasters globally has steadily declined. The world needs to continue and scale up investment in preparedness, early warning and resilience-building strategies.

Third, leaps forward in science and technology continue to improve predictions of climate-related crises, shaping anticipatory actions and allowing faster action when disaster is about to strike.

Fourth, the most vulnerable countries need greater access to contingency finance and insurance for rapid response and recovery at a larger scale.

Fifth, overlapping vulnerabilities need to be reflected in the operations of international financial institutions. As a recent IMF and World Bank report recognized, a combination of debt burdens, climate change and environmental degradation as a “systemic risk to the global economy.”

Lowcock stressed that there are far more solutions out there. “Researchers and organizers in the most vulnerable countries will have far more innovative and wise ideas than I for how to mitigate and adapt to the risks of climate change,” he concluded. “The world should listen to them.”

Reach the speech .

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Healing Chile’s Huapi Island

On Chile’s Huapi Island, native forests have become fragmented, making the soils poorer and drier and leaving the population vulnerable to the effects of climate change. Now, thanks to the restoration efforts of Indigenous Peoples, native trees are making a comeback.

Early warning systems are saving lives in Central Asia

As Central Asia grapples with the increasing frequency and severity of climate-induced hazards, the importance of robust early warning systems cannot be overstated. However, countries need both technical knowledge and resources to effectively implement these systems on a large scale. Japan has been a reliable ally for countries, helping advance early warning systems and increase resilience in the region.

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Global Environmental Change: Understanding the Human Dimensions (1992)

Chapter: 4 human consequences and responses, 4 human consequences and responses.

Since before recorded history, environmental changes have affected things people value. In consequence, people have migrated or changed their ways of living as polar ice advanced and retreated, endured crop failures or altered their crops when temperature and rainfall patterns changed, and made numerous other adjustments in individual and collective behavior. Until very recently, people have responded to global phenomena as if they were local, have not organized their responses as government policies, and have not been able to respond by deliberately altering the course of the global changes themselves. Things are different now from what they have been for millennia.

This chapter examines the range of human consequences of, and responses to, global environmental change. We begin by developing the concept of human consequences and showing why, to understand them, it is critical to understand the variety of human responses to global change. We then offer a framework for thinking about human responses and discuss the pivotal role of conflict. The next section examines three cases that illustrate many of the major factors influencing the human consequences of global change. The following sections describe the human systems that are affected by or respond to global change, and how they interrelate. We conclude by offering some general principles for research and some research implications.

UNDERSTANDING HUMAN CONSEQUENCES

Many human actions affect what people value. One way in which the actions that cause global change are different from most of these is that the effects take decades to centuries to be realized. This fact causes many concerned people to consider taking action now to protect the values of those who might be affected by global environmental change in years to come. But because of uncertainty about how global environmental systems work, and because the people affected will probably live in circumstances very much different from those of today and may have different values, it is hard to know how present-day actions will affect them. To project or forecast the human consequences of global change at some point in the relatively distant future, one would need to know at least the following:

the future state of the natural environment,

the future of social and economic organization,

the values held by the members of future social groups,

the proximate effects of global change on those values, and

the responses that humans will have made in anticipation of global change or in response to ongoing global change.

These elements form a dynamic, interactive system (Kates, 1971, 1985b; Riebsame et al., 1986). Over decades or centuries, human societies adapt to their environments as well as influence them; human values tend to promote behavior consistent with adaptation; and values and social organization affect the way humans respond to global change, which may be by changing social organizations, values, or the environment itself.

This complex causal structure makes projecting the human consequences of global change a trickier task than is sometimes imagined. It is misleading to picture human impacts as if global change were like a meteorite striking an inert planet, because social systems are always changing and are capable of anticipation. So, for example, an estimate of the number of homes that would be inundated by a one-meter rise in sea level and the associated loss of life and property may be useful for alerting decision makers to potentially important issues, but it should not be taken as a prediction, because humans always react. Before the sea level rises, people may migrate, build dikes, or buy insurance, and the society and economy may have changed so that people's immediate responses—and therefore the costs of

global change—may be different from what they would be in the present.

One may imagine human consequences as the output of a matrix of scenarios. Assume that four sets of scenarios are developed for the futures of the natural environment, social and economic organization, values, and policies. Joining together all combinations of one scenario from each set, and adding assumptions about people's immediate responses, would generate an extensive set of grand scenarios. The human consequences of global change could then be defined as the difference between the state of humanity at the end of one grand scenario and the state of humanity at the end of a base case or reference scenario with a different natural-environment component. By this definition, a particular change in the natural environment has different consequences depending on the scenarios assumed for society, values, and responses.

Building these scenarios, identifying the most probable ones, and assessing their outcomes would be an overwhelming analytic task. Rather than trying to set a research agenda for that task, we undertake in this chapter a less demanding but still very difficult task: to focus on human responses to global change broadly conceived. We do not discuss ways to improve forecasts of the state of the natural environment; that topic is outside the range of human dimensions. Neither do we devote much attention to improving forecasts of social and economic organization or of human values, even though these topics clearly belong to the social sciences and are critical to understanding the effects of global change. We bypass these issues because the need for improved social, economic, and political forecasting is generic in the social sciences, and addressing this broad need would take us far beyond our charge to focus on human-environment interactions. We offer only limited discussion of how future global change might proximally affect what humans value, because the variety of possible global changes and the uncertainty about the effects of each make it far too difficult to go into detail. Instead, we review basic knowledge about how human systems respond to external stresses, in the context of discussing human responses.

In our judgment, understanding human responses is key to understanding the human consequences of global change. We do not mean to downplay the importance of certain kinds of research that do not focus explicitly on responses. Two such research traditions, in particular, are highly relevant. The impact-assessment tradition involves projecting the human consequences of a

range of natural-environment scenarios under given assumptions about human response. The tradition of post hoc case analysis involves assessing the actual human outcomes after past environmental changes (and given the responses that actually occurred), in the hope of drawing more general conclusions. Research in these traditions, combined with analysis of human response, can offer valuable insights into the human consequences of global change. We discuss that research as appropriate in this chapter and in Chapter 5 .

S OME D IMENSIONS OF H UMAN R ESPONSE

The human responses relevant to global change differ along several dimensions. We consider the following analytic distinctions useful for thinking about the range of responses available.

Responses to Experienced Versus Anticipated Change

People and social institutions may respond to environmental change as it is experienced (post facto) or as it is anticipated. 1 In the past, people responded mainly to experienced environmental change; only in very recent history, because of increasing scientific knowledge, has there been any rational basis for anticipatory responses. Policy makers and others are now faced with a variety of options, some of which involve anticipatory action and some of which depend on awaiting the experience of global change.

Deliberate Responses Versus Actions with Incidental Effects

Some human actions can be taken deliberately in response to global change. For instance, people can build dikes to keep out rising seas or reduce greenhouse gas emissions to mitigate global warming. Human actions can also affect human responses to global change incidentally to their intended purposes. For example, European settlement of the Americas gave Europeans and, later, others access to a wider variety of food crops, making human survival less dependent, at least in principle, on a small number of staples that might be vulnerable to altered growing conditions caused by environmental change. World markets have subsequently reduced the number of major staple foods so that, in practice, people may eat no larger a variety of foods than before (Plotkin, 1988). High taxes on gasoline in Europe and Japan, enacted for reasons unrelated to the global environment, encouraged

development and purchase of small, fuel-efficient automobiles that incidentally slow the pace of global warming. By bringing about technological change, these taxes also incidentally have helped make it easier for all countries—even those without high gasoline taxes or companies that produce fuel-efficient automobiles—to respond to the challenge of global warming with improved energy efficiency.

Changes in society that incidentally affect human responses to global change are important both directly and because they could become tomorrow's deliberate responses. For example, gasoline taxes, which were not initiated with the global environment as a consideration, could be increased to cut CO 2 emissions. Studies of the incidental effects of such actions might inform decision makers about what could happen without deliberate intervention and about which present policies might make societies more robust in the face of global change. Both kinds of knowledge are essential for informed policy debates.

Coordinated Versus Uncoordinated Responses

Response to global change may be coordinated, as through the policies of governments or trade associations aimed at eliciting the same action from many actors, or uncoordinated, as with independent actions of households or small firms. Both types of response can be either anticipatory or post facto; both can affect global change either deliberately or incidentally. Moreover, coordinated and uncoordinated responses can be connected to each other, in that coordinated actions by governments and industries can create new options for uncoordinated actors, prohibit responses, or raise or lower their costs.

Interventions at Different Points in the Process

Figure 4-1 elaborates on Figure 2-2 to show how human action can intervene at any point in the cycle of interaction between human and environmental systems to protect against threats to what humans value. We offer the following rough distinctions among types of interventions. 2

The term mitigation is generally used to describe interventions on the human causes side of the diagram. Mitigation includes all actions that prevent, limit, delay, or slow the rate of undesired impacts by acting directly or indirectly on environmental systems. Mitigation can operate at various points in the causal cycle.

Interactions between human and environmental systems and the role of various types of human response. Lightly shaded boxes repeat the relationships presented in Figure 2-2 .

It may involve direct interventions in the environment (type E in the figure) to counteract the effects of other human actions, direct interventions in the proximate human causes (type P), and interventions in the human systems (type H) that drive global change, intended to have an indirect or downstream effect on the proximate causes.

For example, global warming is the direct result of a change in the earth's radiative balance; humans can mitigate global warming by any actions that slow the rate of change or limit the ultimate amount of change in the radiative balance. 3 They can intervene in the environment (type E), for example by directly blocking incident solar radiation with orbiting particles or enhancing the ocean sink for carbon dioxide by adding nutrients. They can intervene in the proximate causes (type P), by regulating automo

bile use or engine design to cut carbon dioxide emissions or limiting the use of certain nitrogen fertilizers to reduce nitrous oxide emissions. They can intervene in human systems (type H) and indirectly control the proximate causes, by investing in research on renewable energy technologies to replace fossil fuel or providing tax incentives for more compact settlements to lower demand for transportation.

Mitigation of ozone depletion might, in principle, involve release of substances that interact chemically with CFCs, producing compounds with benign effects on the stratospheric ozone layer (type E), limiting emissions of chlorofluorocarbons (CFCs) and other gases that deplete ozone (type P), or developing alternative methods of cooling buildings that do not rely on CFCs (type H). Mitigation of threats to biological diversity might include, at least in principle, engineering new varieties, species, or even ecosystems to save diversity, if not individuals (type E); limiting widespread destruction of tropical forests, estuaries, and other major ecosystems (type P); or promoting systems of land tenure and agricultural production that decrease the pressure for extensive development of tropical forests (type H).

Humans can intervene in several ways on the response side of the cycle. Such actions are sometimes generically called adaptation , but there are important distinctions among them. One type of response, which can be called blocking , prevents undesired proximate effects of environmental systems on what humans value. It can be described by example. If global climate change produces sufficient warming and drying (drought) on a regional scale, it may threaten the region's crops; development and adoption of drought-resistant crops or crop strains can break the connection between environmental change (drought) and famine by preventing crop failure. Similarly, loss of stratospheric ozone threatens light-skinned humans with skin cancer, through exposure to ultraviolet radiation; avoidance of extreme exposure to sun and application of sunscreens help prevent cancer, although they do not mitigate the destruction of the ozone layer. Tropical deforestation threatens species with extinction by eliminating their habitats; creation of forest preserves would provide many species sufficient habitat to survive, while doing little to slow net deforestation.

Another type of adaptive response is to prevent or compensate for losses of welfare that would otherwise result from global change. Such actions can be called adjustments . 4 They neither mitigate environmental change nor keep it from affecting what people value, but rather intervene when a loss of welfare is imminent or after

it has begun to be manifest. Examples include evacuation from areas stricken with flood or drought, food shipments or financial assistance to those remaining in such areas, and development of synthetic substitutes for products previously obtained from extinct species. 5

Yet another type of response, sometimes called anticipatory adaptation, aims to improve the robustness of social systems, so that an unchecked environmental change would produce less reduction of values than would otherwise be the case. 6 This type of intervention does not alter the rate of environmental change, but it lowers the cost of any adjustments that might become necessary. It can be distinguished, at least in theory, from type H mitigation in that it does not necessarily alter the driving forces of global change. An example is diversification in agricultural systems. Farmers, regions, and countries that rely on a range of crops with different requirements for growth may or may not produce less greenhouse or ozone-depleting gases than monoculturists. But polycultures are more robust in the face of drought, acid deposition, and ozone depletion. There may be crop failure, but only in some crops. Similarly, families and communities that have both agricultural and nonagricultural income are harmed less by the same threats than purely agricultural groups. They have other sources of income and can purchase crops from elsewhere. 7

All social systems are vulnerable to environmental change, and modern industrial societies have different vulnerabilities from earlier social forms. Modem societies have built intricate and highly integrated support systems that produce unprecedented material benefits by relying critically on highly specialized outputs of technology, such as petrochemical fertilizers and biocides; hybrid seeds; drugs and vaccines; and the transmission of electricity, oil, and natural gas from distant sources. Although these complex sociotechnical systems contain great flexibility through the operation of global markets, they may have vulnerabilities that reveal themselves in the face of the changes that these systems have helped create. For instance, modern societies have become highly dependent on fossil fuels and vulnerable to a serious disruption of supply or distribution systems. They also support much larger and denser populations than ever before; such populations may be vulnerable to ecological changes affecting the viability of their food supplies.

Evidence from studies of disasters suggests that the poor, who lack diversified sources of income, political influence, and access to centralized relief efforts, tend to be worst off (Erikson, 1978;

Kroll-Smith et al., 1991; Mileti and Nigg, 1991). However, studies to assess the vulnerabilities of larger human systems, such as national or world food or energy systems, are rarely done (e.g., Rabb, 1983). The far side of vulnerability is also little studied: When a system fails to resist environmental pressure, under what conditions does it return to its previous state? If it undergoes permanent change, what determines the nature of the new state?

T HE P IVOTAL R OLE OF C ONFLICT

An important consequence of global environmental change is conflict, because global change affects what humans value, and different people value different things. When U.S. energy use threatens the global climate or land clearing in Brazil threatens the extinction of large numbers of species, people around the world are understandably concerned. They may express a desire—or even claim a right—to influence the choices of people or governments continents away. And the people or countries subjected to those claims may resist, especially when they feel that changing their behavior will mean suffering. The further global change proceeds, the more likely it seems that it will be a source of conflict, including international conflict, over who has a right to influence the activities implicated as causes, who will pay the costs of responding, and how disputes will be settled.

A Current Controversy: To Mitigate or Not to Mitigate?

One of the most heated policy debates about responses to a global change is between advocates of immediate efforts to mitigate global warming and those who would postpone such action. This debate arose within the committee, even though we were not charged with recommending strategies for response to global change. We offer the following brief, sharply stated version of the debate to highlight some important characteristics of controversies about global change: that they are partly, but not entirely, fact-based; that they are likely to persist even in the face of greatly increased knowledge about the causes of global change; and that they are pervasive, even in discussions restricted to research priorities.

In one view, the wise course of action on global warming is to conduct research on the phenomenon but not to take action to slow or mitigate it until the phenomenon is better understood. Proponents of this view make the following arguments:

Uncertainty of global change . The nature and extent of global warming in the future is highly uncertain because of incomplete knowledge of the relevant properties of the atmosphere, oceans, biosphere, and other relevant systems. It is wasteful for society to expend resources to prevent changes that will not occur anyway. Moreover, the mitigation efforts may themselves set in motion undesired changes.

Adjustment will make mitigation unnecessary . Human systems can adjust to global climate changes much faster than they are likely to occur. The projected doubling of atmospheric carbon dioxide levels will take place about 80 years from now. By contrast, financial markets adjust in minutes, administered-market prices in weeks, labor markets in years, and the economic long run is usually reckoned at no more than two decades. The implication for action is that what individuals and organizations do on their own in anticipating climate change may be sufficiently successful that organized, governmental responses will be superfluous. The impact of climate change will reach people through slow price increases for the factors of production; in reasonably well-functioning markets, economic actors adapt readily to such changes. They invent industrial processes that economize on scarce inputs, find substitutes, purchase energy-efficient equipment when energy prices are rising, and so forth. In the past, such adjustments have contributed to human progress, and there is every reason to expect that pattern to continue.

Don't fight the wrong war . It makes no sense to act like the generals who built the Maginot Line for the wrong war or to construct dikes for cities whose populations will have moved or dams to water crops that will be grown elsewhere. Technological and social changes often eliminate problems without any specific mitigation efforts by changing the offending technology or making it obsolete. For example, boilers no longer explode on trains because they no longer use steam engines; horses are no longer the main polluters of urban streets. Concern about the greenhouse effects of fossil fuel burning will prove premature if development of fusion or solar energy technology can replace most fossil fuel use over the next 50 years.

Better policy options may lie on the horizon . Further research may identify more effective and less costly interventions than those now available. For example, it has recently been suggested that adding iron to the oceans to fertilize phytoplankton that would absorb carbon dioxide from the atmosphere may be a way to address the greenhouse effect (Martin et al., 1990). That

proposal, whatever its ultimate feasibility or desirability (Lloyd, 1991), demonstrates that improved understanding of biogeochemical systems might generate promising new proposals for mitigating global change. Improved understanding of social systems has reasonable potential to discover other classes of effective response.

It may be more costly to act now . Actions that can be postponed will be less burdensome because of continuing economic progress. If people living in the 1890s had invested in preventing today's environmental problems, their expense on our behalf would probably have been made on the wrong problems, and it would have been an inequitable transfer of resources from a poorer generation to a richer one. It probably makes no more sense for the current generation to sacrifice to benefit a future, even wealthier generation. This is the argument for a positive social discount rate. It assumes that expenditures made now could otherwise be invested at compound interest in improvements in human well-being. If the growth rate for such investment exceeds the average rate at which environmental problems develop, people will be better off in the future if they do not spend on mitigation now.

Proponents of immediate mitigative action make the following arguments:

Action now is more feasible and effective than action later . It is in the nature of exponential growth processes that the earlier the growth rate decreases, the greater the final effect. Bringing down the birth rate in India to two children per couple in 1995 rather than in 2005 can make a difference of 300 million people by the time the Indian population stabilizes (Meadows, 1985). To achieve the same effect by starting later would impose greater restrictions on the people living at that time. It is therefore easier to mitigate the effects of exponential growth the sooner the effort is made.

It is easier to adjust to slower change . Mitigation is prudent because of the long time lags in the global environmental system. By the time it becomes clear that a response is needed, it may be too late to prevent catastrophe if the change is proceeding rapidly. Even if catastrophe is unlikely, mitigation that slows the rate of change makes it more likely that adjustments can be made in time. This is clearly the case for nonhuman organisms, such as tree species that can adjust to climatic change by migrating, as seedlings move to more favorable locations. Such species have a

maximum rate of migration, so can adjust to climatic change below that rate. 8 The same principle probably also applies to human adjustments to major environmental change.

It is wise to insure against disaster . Mitigation in the face of possibly catastrophic outcomes is like taking out insurance against flood and fire. The insurance expenses are bearable, but the expenses of catastrophe may not be.

Avoid irretrievable error . It is wise to mitigate against potentially irretrievable losses. The clearest example is species extinction. If species are valued for themselves, their loss is irretrievable; even if they are valued only for what benefits they may have for humanity, species loss may be irretrievable. Other environmental values, such as loss of the life-supporting capacity of wetlands or large bodies of water, may also be irretrievable; often we do not know until the values are lost.

Avoid high-risk environmental experiments . Humans are now conducting large-scale uncontrolled experiments on the global environment by changing the face of the earth and the flows of critical materials at unprecedented rates. It is prudent to limit the pace and extent of such experiments because of the likelihood of unanticipated consequences. Like natural mutations, most of these experiments are probably destined to fail, and there is only one global environment to experiment on. As the extent of human intervention in the global environment continues to increase, so does the strength of this argument. The argument supports mitigation efforts that slow ongoing human interventions in the environment, but generally not those that would stop greenhouse warming by new interventions in the global environment.

Economic arguments do not encompass some environmental goods . The discount-rate argument is specious in the general case because the costs and benefits of postponing action are not always commensurable. Some important and meaningful tradeoffs can be made on economic grounds, for instance, between investing in renewable energy development and in directly limiting the burning of fossil fuels. But sometimes the economic logic makes no sense. If current economic activity destroys die life-support systems on which human life depends, what investment at compound interest could ever recoup this cost? Economic arguments also cannot deal with some things—including the balance of nature—on which people place intrinsic or spiritual value. To the extent people want to preserve such values, mitigation is the only acceptable approach. Moreover, economic accountings systematically undervalue things—such as genetic resources—for

which there are few property rights or for which economic value is only potential.

Some mitigative action is fully justified on other grounds . A good example is investments in energy efficiency that provide an excellent return on investment even with narrow economic calculations. Such actions can achieve the benefits of mitigation at no extra cost, while providing other benefits.

Implications of Conflict About Human Response

Many controversies are beginning to develop out of concerns with global change. One pits Third World countries against the developed countries that are now becoming concerned with limiting use of fossil fuels and restricting the felling of tropical forests. The Third World position, of course, is that other countries used fossil fuels and undeveloped frontiers for their economic development, and fairness dictates that the poorer nations now have their turn. Many analysts believe that if large-scale climate change results from human activities, the poorer countries are likely to suffer most because they lack resources they could use to adapt. Such an outcome would produce yet other conflicts.

The controversies about global change are only partly fact-based. True, some of the disagreements might fade with better knowledge about the global environment and the likely effects of different feasible responses. As it became clear that expected global warming over the next 50 years could not cause the breakup of the West Antarctic icecap, the flood-prevention rationale for slowing greenhouse gas emissions became considerably weaker. A response such as dike building seems much more appropriate when the sea threatens only a few areas. And if it became clear what each policy option—at the local, national, and international levels—would accomplish if enacted, some of them could easily be rejected.

But knowledge often fails to resolve controversy. It frequently raises new disputes or calls old beliefs into question. And even when new knowledge reduces uncertainty, controversies persist because not only facts, but also important interests and values, are at stake. Informed people disagree because the remaining uncertainty leaves room for judgment, because they may assume different scenarios about the future of society, and because an outcome that harms what one person values may enhance what another values. Those impressed with the potential benefits of economic growth tend to line up against those who fear of the

potential costs; those with a strong faith in the ability of human ingenuity to solve life's problems line up against those awed by what is at stake; those who stand to benefit from an outcome line up against those who stand to lose. When faced with choices, some prefer international solutions to global problems, others see national action as more feasible; some favor market adaptations, others, community-based action outside the market and the state; some are attracted to large-scale technological solutions, others see them as cures that may be worse than the disease. In short, the debates are not only about the workings of human and environmental systems, but also about political and economic interests, conflicting values and faiths, differing assumptions about the future, and different judgments about resiliency in the face of the unexpected.

Research on Conflict Studies of environmental and technological conflict are a significant part of social research on conflict (e.g., Nelkin, 1979; Mazur, 1981; Freudenburg and Rosa, 1984; Jasper, 1988; Clarke, 1989). Issues of global environmental change have all the features characteristic of the most difficult technological controversies: awareness of human influence on the hazards, serious worst-case possibilities, the possibility of widespread and unintended side effects, delayed effects not easily attributable to specific causes, and lack of individual control over exposure (National Research Council, 1989b:57-62).

Social science can help illuminate the nature of environmental controversies and evaluate ways of managing them. Social scientists interested in environmental policy have studied the conditions shaping and favoring the resolution of environmental controversies and the role of scientific, governmental, and mass media communication in the decision process (e.g., Dietz and Rycroft, 1987; Gould et al., 1988; Jasanoff, 1990; Nelkin, 1979, 1988; National Research Council, 1989b). Some have begun to consider the various ways environmental change might lead to conflicts with the potential for violence (e.g., Homer-Dixon, 1990).

Social scientists specializing in conflict have developed generalizations that might be more thoroughly applied to environmental conflict. For example, conflicts may be based mainly on ideology, interest, or understanding (Aubert, 1963; Glenn et al., 1970; Rapoport, 1960, 1964; Hammond, 1965; von Winterfeldt and Edwards, 1984; Syme and Eaton, 1989), and different types of conflict tend to yield to different tactics of resolution (e.g., Druckman and Zechmeister, 1973; Druckman et al., 1977). Defining an environ-

mental conflict as either one of understanding or one of interests and values affects which groups and arguments are considered legitimate in policy debates (Dietz et al., 1989). The nature of the relationship between the parties to a conflict can determine whether the conflict focuses on ideological positions (e.g., Campbell, 1976; Zartman and Berman, 1982), differences in understanding (e.g., Axline, 1978), or differences in interests (e.g., Strauss, 1978). And the behavior of the parties to a conflict depends on the pattern and relative strength of incentives to compete and to cooperate (e.g., Pruitt and Kimmel, 1977), the probability of continued interaction in the future (e.g., Axelrod, 1984), and on whether two or more parties are involved (Groennings et al., 1970; Hopmann, 1978; Putnam, 1988).

More research seems warranted to use existing knowledge about conflict to illuminate the ways social conflict may result from global environmental change. This research would investigate the ways environmental changes may affect organized social groups and their resource bases and would hypothesize links between those effects and conflict. A first step is to construct an analytical framework for identifying the possible routes from particular environmental changes to particular types of conflict. The framework of Homer-Dixon (1990) provides a start, for causes of violent conflict. Case analyses of past social conflicts can be used to assess hypotheses drawn from such analytic frameworks.

Research on Conflict Resolution and Management Social scientists have also identified a number of approaches for resolving or managing policy disputes, some of which are beginning to be studied in the context of environmental conflicts. These include mediation techniques intended to address the value dimension of environmental conflict (e.g., Ozawa and Susskind, 1985); facilitation procedures that emphasize problem-solving discussions and have proved useful as a prelude to negotiation (Burton, 1986; Druckman et al., 1988); techniques of separating values from interests to makes conflicts appear smaller and easier to solve (Fisher, 1964; but see Druckman, 1990); efforts to focus on shared principles for decisions (Zartman and Berman, 1982) or to discuss values as ranked priorities rather than ideological differences (Seligman, 1989); policy exercises that emphasize creative use of scientific knowledge to solve environmental problems (Brewer, 1986; Toth, 1988a, b); and computer software for dealing with the cognitive and political aspects of both conflicts over the interpretation of data for environmental management (Hammond et al., 1975; Holling, 1978).

The nature of technological conflicts suggests, however, that over the long-term, management is a more realistic goal than stable resolution. Recent work on risk communication is potentially relevant to social responses to global change because global change problems, like those to which that literature refers, are characterized by high levels of scientific uncertainty and great potential for conflict about social choices (Covello et al., 1987; Davies et al., 1987; Fischhoff, 1989; National Research Council, 1989b; Stern, 1991). This work suggests that institutions responsible for decisions about global change will also have to manage conflict. These institutions will need to provide accurate information, but should not expect information to resolve conflict. The institutions will need to make a place for the stakeholders to be represented from the earliest stages of the decision process, ensure openness in processes of policy decision, include mechanisms for the main actors to have access to relevant information from sources they trust, and use the conflicting perspectives and interpretations of current knowledge and uncertainty to inform the ongoing debate (National Research Council, 1989b; Stern, 1991).

Research Needs Relatively little is known about the structure of particular conflicts about global change at the local, national, and international levels or about which means will be most effective in dealing with them. Therefore, we recommend increased empirical research, including both field studies and laboratory-simulation studies, to clarify the sources and structures of particular environmental conflicts and to test the efficacy of alternative techniques for their resolution and institutions for their management.

HUMAN RESPONSE: THREE CASES

In Chapter 3 we presented cases to illustrate how human actions can contribute to the causes of global change. Here we present three cases to illustrate the human consequences of, and responses to, environmental change. Taken together, they show the importance of all the major human systems involved (described later in the chapter) and the ways that conflicts are played out and choices made within these systems.

I NTERNATIONAL R EGULATION OF O ZONE -D EPLETING G ASES

As mentioned earlier, the most successful effort to date to address a global environmental problem by international agreement

is the ozone regime, articulated in the 1985 Vienna Convention for the Protection of the Ozone Layer, the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer, and the 1990 London Amendments to the protocol. This regime, in its current form, commits its members to phasing out the production and consumption of CFCs and a number of related chemicals by the year 2000. The regime represents the first concerted international effort to mitigate ''a global atmosphere problem before serious environmental impacts have been conclusively detected'' (Morrisette, 1989:794).

The political history of the ozone regime begins as a national issue in the United States and a handful of other Western countries in the early 1970s, in connection with emissions from supersonic transport (SST) aircraft and then from aerosol spray cans (Downing and Kates, 1982; Morrisette, 1989). Environmental groups organized opposition to the development of the SST and to the extensive use of aerosols. Individual responses led to a sharp drop in sales of aerosol products (Morrisette et al., 1990). The U.S. Congress, prodded by government studies supporting the CFC-ozone depletion theory and its links to skin cancer, approved the Toxic Substances Control Act of 1976, which among its other provisions, gave the Environmental Protection Agency (EPA) the authority to regulate CFCs. In 1978, the United States became the first country to ban the nonessential use of CFCs in aerosols. However, the EPA ruled that other uses of CFCs, such as in refrigeration, were both essential and lacked available substitutes.

Ozone depletion emerged as a major international issue in the 1980s. This occurred primarily as a result of initiatives by the United Nations Environment Programme (Morrisette, 1989) and the actions of the international scientific community (Haas, 1989), with the support of the international environmental movement. The Vienna convention of 1985 embodied an international consensus that ozone depletion was a serious environmental problem. However, there was no consensus on the specific steps that each nation should take.

A number of events in 1986 and 1987 created a new sense of urgency about the depletion of stratospheric ozone. These included a rapid growth in demand for CFCs due to new industrial applications and the end of a global economic recession; important new studies by the World Meteorological Organization, the National Aeronautics and Space Administration, the Environmental Protection Agency (EPA), and the United Nations Environment Programme; and, most important, the widely publicized

discovery by scientists of the Antarctic ozone hole in 1985. In January 1986, EPA initiated a series of workshops designed to build an international scientific consensus supporting the need to control the use of CFCs. In the same year, DuPont announced that its scientists had determined that CFCs were the most likely cause of ozone depletion. These events persuaded American officials of the need for decisive international action. When negotiations on a protocol to the Vienna convention for controlling CFCs resumed in December 1986, the United States adopted a firm position, calling for an international treaty not only freezing production of CFCs but also reducing production and consumption.

Following extensive and complex negotiations, the Europeans, whose earlier opposition to a cutback in production had prevented agreement in Vienna, moved closer to the U.S. position. They were persuaded to do so by three factors: the weight of scientific evidence, pressures from their own domestic environmental groups, and the fear that, in the absence of a treaty, the United States might take unilateral action to impose trade sanctions. While compromises on several controversial points proved sufficient to gain Japanese and Soviet adherence, the major developing countries (e.g., China and India) did not become signatories to the Montreal Protocol.

Only after the Montreal Protocol was signed did the full extent of ozone depletion became public: ozone depletion over Antarctica reached a historic high in 1987, and the link to the release of CFCs became a matter of scientific consensus. DuPont responded by announcing that it planned to discontinue CFC production by the end of the century and, in March 1989, 123 countries called for the absolute elimination of production by the same date. A resolution agreeing to totally phase out all production and consumption of CFCs by the year 2000 was adopted by 81 countries in May 1989 at the first governmental review of the Montreal Protocol.

Taking advantage of this momentum, the parties to the Montreal Protocol, meeting at a review conference in London in June 1990, were able to negotiate a series of strong amendments. These amendments accelerate the phaseout schedule for CFCs and halons and add methyl chloroform and carbon tetrachloride to the list of chemicals to be eliminated. Equally important, the amendments establish an international fund to be used to assist developing countries in switching to substitutes for CFCs in the production of refrigerators and air conditioners. On the strength of this

development, both China and India agreed to become members of the international ozone regime.

Why was it possible to reach a broad international agreement restricting CFCs? Analysts have identified four important factors: an evolving scientific consensus; a high degree of public anxiety in developed countries about the risks associated with the continued use of CFCs, due in large measure to an association with skin cancer; the exercise of political muscle by the United States; and the availability of commercial substitutes for CFCs (Haas, 1989; Morrisette, 1989). The last served the critical role of diminishing the opposition of the chemical industry to a phased reduction. When DuPont, the producer of 25 percent of all CFCs, decided to develop substitutes, it "forced other CFC manufacturers to follow suit or risk losing market share" (Haas, 1989:11). Haas adds that, because this issue could be resolved by a technical fix, it did not involve any hard choices and therefore may be unique in the annals of global environmental change.

Another important influence in getting CFCs on political agendas may have been the efforts of the scientific community, which has been influential in drawing attention to other environmental problems (Haas, 1991). Haas (1989) notes that it was initially a group of atmospheric physicists and chemists, most of whom worked in the United States, who attempted to place the issue of ozone depletion on the national and global environmental agendas, and that this community continued to press the issue throughout the 1980s. He argues that the speed of policy response in the United States may have been due to the "highly fragmented nature of American government and society [which] facilitates access of a strongly motivated group of technical experts" (p. 8). Thus, the access of a key group to policy debates at the national level may have influenced international action on CFCs.

The history of the ozone regime illustrates a number of key variables that affect the likelihood of reaching similar agreements on other global environmental problems (Sand, 1990b; Benedick, 1991). Further studies are desirable to clarify how these variables interact:

the emergence of scientific consensus on the causes of global environmental change;

the number of actors responsible for the proximate causes of the global change;

the nature and global distribution of the harm that might result from inaction;

the distribution of the burdens of regulation on the consumers, producers, and employees whose behaviors must change;

the importance of national regulations as a precursor to the emergence of international ones; and

the need for strong leadership in international forums.

It also suggests that international agreements can be affected by the structures of national political systems, informal international communities, and markets that would be critically affected by agreement.

T HE U.S. E NERGY C ONSERVATION A CHIEVEMENTS OF 1973-1985

Energy efficiency is probably the most widely accepted strategy for mitigating global warming. The energy shocks of the 1970s led to significant improvements in the energy productivity of Western industrialized economies. The U.S. experience is typical and instructive.

Between 1973 and 1985, the United States reduced its energy intensity—the ratio of energy use to economic output—by 25 percent. 9 Other industrialized capitalist countries made similar achievements, reducing energy intensity, usually from much lower initial levels, by an average of 21 percent during that period (International Energy Agency, 1987). The change was a sharp contrast to the record of the previous two decades and to most of the twentieth century. Between 1953 and 1973, U.S. energy intensity was almost steady, decreasing at an average of 0.1 percent per year; at only two earlier periods in the century, 1918-1926 and 1948-1953, did energy intensity decrease at a rate above 2 percent per year (Schurr, 1984). To the extent that energy intensity can continue to improve in the United States and other countries, energy efficiency can make an enormous contribution to mitigating global warming. This section takes a closer look at how and why the change occurred in the United States and the implications for other countries.

Preexisting Trends

After increasing for 40 years, U.S. energy intensity declined fairly steadily between 1920 and 1953, before stabilizing for 20 years (see Table 4-1 ). Although the reasons are not well understood, the secular decline in energy intensity since 1920 has been attributed to improved efficiency in energy conversion, a

TABLE 4-1 Average Annual Percentage Rates of Change in Total Output and Energy Intensity in the United States Private Domestic Business Economy, 1899-1981

shift in the economy away from heavy manufacturing, and technological improvements throughout the economy associated with a shift to more flexible energy sources: oil, gas, and electricity (Schurr, 1984). The decrease in energy intensity with the 1973 oil shock, and again with the 1979 shock, marked a sharp break from the previous 20 years; from 1973-1981, intensity decreased at a rate about 2 1/2 times the average of the previous 53 years.

Uncoordinated Responses to Recent Events

The behavioral change after 1973 was largely due to the oil shocks of 1973 and 1979, which rapidly altered energy prices, changed perceptions of the future price and availability of fossil fuels, and brought about policy changes. Energy users made three effective kinds of responses (U.S. Department of Energy, 1989; Schipper et al., 1990). First, they changed the way they operated energy-using equipment, curtailing heat and travel, and improving management, such as by tighter maintenance of furnaces. Such changes accounted for 10-20 percent of national energy savings achieved in 1986 (compared with the pre-1973 trend; estimates from U.S. Department of Energy, 1989) but are easily reversed when energy prices drop or incomes rise, as they did in the 1980s.

Second, energy users adopted more energy-efficient technology to provide the same service with less energy use, either by retrofitting existing equipment (e.g., insulating buildings, installing reflecting windows) or by replacing existing equipment with more energy-efficient models. These improvements were responsible for 50-60 percent of total energy savings by 1986.

Third, the mix of products and services in the economy changed. Demand fell sharply in energy-intensive industries, such as primary metals, relative to less energy-intensive industries; small cars got an increased share of the automobile market; and commercial airlines improved the match between aircraft size and demand on passenger routes. Together, such shifts accounted for about 20-30 percent of the energy savings achieved in 1986.

Higher real energy prices are generally considered the most important single explanation for these responses (International Energy Agency, 1987; U.S. Department of Energy, 1989). However, price is not the whole story. Although the two energy shocks of the period had very similar price trajectories, the effects on the economic productivity of energy differed markedly after the first two years (see Figure 4-2 ). For the first two years of each shock, real energy prices increased about 40 percent and energy productivity increased about 5 percent. But over the longer-term, the second shock had much more effect than the first. A five-year price increase of about 45 percent in 1973-1978 increased energy productivity 7 percent; a similar increase in 1978-1983 increased energy productivity 18 percent. Moreover, the trend continued through several years of falling real energy prices.

Why the different reactions to the two energy shocks? One explanation is perceptions: it took the second shock to get energy

FIGURE 4-2 Changes in indexed real energy prices and energy intensity in the U.S. economy after the energy shocks of 1973 (A) and 1979 (B).

users' attention—to convince them that higher energy prices were here to stay. Another is that the decision environment had changed by 1979 in ways that made it more likely the system would respond to price signals. Government policies to promote energy-efficient technology and provide necessary information were in place by 1979, making it easier for energy users to respond effec-

tively to price; the learning curve for policy implementation had had time to progress; and entrepreneurs were ready to offer energy-efficient technologies and management programs that had not been developed in 1973. Moreover, U.S. energy inefficiency had helped open the door to foreign competition in the automobile, steel, and other industries, with the result that U.S. firms began taking efficiency of all kinds more seriously. Because these explanations reinforce each other, it is difficult to estimate their relative magnitude.

The multiple explanations suggest that the price effect depends on other factors: technological change, policy choices, change in industrial structure, and information processing by energy users. Since these factors can be changed independently of energy prices, it seems likely that with appropriate policies in place, energy intensity might have improved faster than it did, even in the apparently price-responsive 1979-1985 period.

Policy Responses and Implementation

Energy conservation policy in the United States has been predicated on the theory that government should intervene chiefly to correct so-called market imperfections such as the tendency of a supply system based on market prices to produce too little environmental quality (because individual consumers cannot be charged for it) and too little information on energy-efficient technologies and their costs. The government can also intervene to mitigate regulatory and institutional barriers to the functioning of the price system. Following this theory, many U.S. efforts to promote energy efficiency have relied on positive financial incentives (e.g., tax credits, utility rebate programs) and on information. Experience with these efforts shows that the market imperfection theory needs to be expanded to take into account deviations in energy users' behavior from conventional economic rationality. 10 Often, rather than making decisions based on minimization of long-run costs, as theory postulates, energy users act on the basis of nonfinancial values (such as environmental preservation, interest in new technology, or enhancement of social status) or are influenced by information from informal social networks rather than more accurate expert information (see Stern and Aronson, 1984, for a review of evidence). Such processes within individuals and small groups have impeded the effectiveness of conservation programs in the United States, but when they are taken into account, programs became much more effective.

Evaluations of incentive and information programs show that, although they are sometimes very effective at increasing the pace of adoption of available technology, success varies greatly, even between nominally identical programs (Berry, 1990). For instance, home energy rating systems reach between 2 and 100 percent of homes, depending on the market (Vine and Harris, 1988), and utility companies offering exactly the same financial incentive program for home retrofits typically have participation rates that vary by a factor of 10 or more (Stern et al., 1986a).

Success depends on a number of features of implementation. A key is getting the attention of potential participants with appropriate marketing efforts, targeting of audiences, selection of trustworthy sources of information, and other basic principles of communication (Berry, 1990; Ester and Winett, 1982; Stern et al., 1986a; Vine and Harris, 1988; Dennis et al., 1990). Getting people's attention appears to be the main barrier to the success of financial incentive programs for home retrofits, so that, paradoxically, "the stronger the financial incentive, the more the program's success depends on nonfinancial factors" (Stern, 1986:211). Apparently, larger incentives ensure success among those who enter a program but do little to attract participants. Finding the proper intermediary, such as a builder, manufacturer, designer, or lender, can also be critical. Home energy rating systems have been introduced most effectively with the active support of the building and lending industries (Vine and Harris, 1988), and residential conservation programs, especially in low-income areas, have often depended for success on involving highly trusted local organizations, such as churches and housing groups (Stern et al., 1986a). Involving consumers in program design can help fit a program to its audience and locale (Stern and Aronson, 1984).

Thus, conservation policies and programs played a part in the U.S. response to the energy shocks of the 1970s, but they could have had a greater effect with better implementation. Improved policies and implementation, along with higher prices, are among the reasons energy productivity improved faster at the end of the 1973-1985 period than at the beginning. These three factors act in conjunction, however. If, for example, energy prices fall or remain stable, lowering energy users' motivation to change, some policy instruments will become less effective than they were in 1973-1985. The trends of the late 1980s demonstrate this effect (U.S. Department of Energy, 1989).

Implications for Future Climate Change

The technological potential for improvements in energy productivity are huge (National Academy of Sciences, 1991b; National Research Council, 1990a). However, the worldwide prospects for implementing technological changes, and therefore for mitigating the release of greenhouse gases, depends on the behavior of several human systems, including world markets for fossil fuels, national policies for economic and technological development and energy management, global social trends in government and the development of technology, and the behavior of individuals and communities.

The world energy price and supply picture will affect the spread of the Western improvements in energy productivity to other countries. Under conditions like those of the late 1980s, with relatively low energy prices and stable supplies, sharp further improvements in installed energy efficiency are unlikely, even in the Western industrialized countries, without new policy initiatives. The price motive for efficiency is weak, policies that rely on that motive are undermined, and the lowered cost of energy is a spur to economic growth, particularly in energy-intensive sectors. Given continuing population and economic growth, those conditions point to increases in energy use in the wealthy countries, although probably not at pre-1973 rates of increase. A new round of sharp price increases would cut energy use both by reducing economic activity and energy intensity, at least for a period.

The world picture also depends greatly on the development paths of growing economies. Industrialization is energy intensive, enough to have overcome the effects of the 1973-1985 oil shocks in relatively wealthy countries, such as Greece and Portugal, that were still industrializing. Consumers' choices are also important. Where increased income goes into homes and durable possessions, as in Japan, energy productivity is more likely to be higher than where it goes into personal transportation, as in the United States, or into refrigerators or other energy-using appliances, as may become the case in China.

The future of the dissolving socialist bloc countries holds many uncertainties. Many of these countries have highly energy-intense economies and therefore seem to have room for improved energy efficiency given the rise of markets and more democratic control of policy. However, they lack finances to develop technology or implement incentive or information programs and need time to design and implement effective policies for local conditions. Whether

development moves in industrial or postindustrial directions is also uncertain. Much room exists for research and for pilot experiments with policy options as ways to reduce the uncertainty.

These and other human systems will determine the extent to which the Western experience with energy efficiency will proceed further or be repeated in other countries. The future will depend on the ways these systems interact in each country and on the ways national and local policies intervene in them.

T HE H UMAN C ONSEQUENCES OF R EGIONAL D ROUGHT IN THE S AHEL

Intensification of the greenhouse effect is likely to alter rainfall patterns on a regional scale. As a rule, regions that receive increased rainfall are likely to benefit; decreased rainfall is the more serious concern. The history of the human consequences of severe drought can be instructive about the variety of human consequences of, and responses to, unmitigated climatic change.

The human role in causing drought in the Sahel region of sub-Saharan Africa is a matter of controversy. Throughout the modern history of drought-famine association in the region, there has been a tendency to interpret extreme events as indicators of trends and to attribute the presumed trends to human mismanagement of the local environment. In fact, Sahelian droughts have been recurrent events. The droughts of the 1970s and 1980s were preceded by several others in this century, one of which, in 1910-1915, resulted in intense famine with high mortality. The controversy over the human role in causing Sahelian drought revived with the drought of 1968-1974. The prevailing view was that desertification was an anthropogenic process reflecting deforestation, overgrazing, overfarming, burning, and mismanaged irrigation resulting in salinization of soil and water.

Lack of good data is a major obstacle to understanding the causes of Sahelian drought. Although some evidence supports the orthodox view, some recent research using remote sensing, field measurements, and intensive investigations of small areas has called that view into question. Observable ecological changes are less significant than had been supposed and correlate better with rainfall records than with land management (Mortimore, 1989).

Different Droughts, Different Responses

The consequences of Sahelian droughts in this century have depended on the ability of indigenous systems of livelihood to

make adaptations. During the century, these indigenous systems have undergone continual change, first as a result of policies of colonial powers, and later in response to postwar development policies promoting ''modernization'' and further integration into the global economy. There are competing views of the effects of these century-long trends in political economy on the ability of local populations to withstand drought. In one view, the main results were increased dependency and vulnerability; in the other, vulnerability decreased because of improved availability of medical care, famine relief, and a national infrastructure that allowed for easier. migration and food shipments (Kates, 1981).

The three major droughts of the century, in 1910-1915, in 1968-1974, and in the 1980s, have had different effects on the lives and livelihoods of the local populations. The 1910-1915 drought, which was of comparable severity to the drought of the 1970s, appears to have produced greater increases in mortality; its effects on malnutrition and on the social fabric are harder to determine (Kates, 1981). The knowledge base is better for comparing the droughts of the 1970s and 1980s. 11 Local conditions changed between those two periods. Population continued to increase at up to 3 percent annually, forests continued to be cut for fuel and farming, and other forms of resource exploitation probably continued at about the previous rates. Grazing pressure fell, owing to animal mortality but, by the 1980s, cattle holdings had recovered to 60 percent of predrought levels in some areas, and small livestock probably recovered more. On balance, the human demands on the local environment were at least as severe as before the 1968-1974 drought.

The drought of the 1980s was as severe as the previous one. Annual rainfall in 1983-1984 was of the same order as in 1972-1973, and in some areas of the Western Sahel, less. Crop failures and pasture shortages were equally serious. Yet famine did not occur on the same scale, and animal mortality was lower. Possibly food aid was earlier and better in some countries, but in northern Nigeria, where food aid was not a major factor in either period, social distress was noticeably less marked in the 1980s, even in the worst affected areas.

What explains the relatively low human cost of the 1980s drought? It was not the response of the affected governments. Political officials were taken by surprise about equally by both droughts. The people most experienced in surviving failures of agricultural production and managing the environment were those living in the affected areas, but this group had little influence on policy. Of the several political interests concerned with the drought prob-

lems, both international and national, the least powerful seems to have been that of the people in the affected areas. Consequently, proposals for new technologies for coping with the drought failed to take indigenous technologies and management systems seriously, and measures to strengthen the poor—for instance by insurance, improved access to resources, alternative job opportunities, and price supports—were rarely considered or given high priority.

A key to drought response appears to have been the role of indigenous forms of land use and response to food shortage. It is possible to distinguish two strategies of land use for areas like the Sahel that face recurrent drought or a long-term threat of declining rainfall. One strategy—maladaptive in the long run—is characterized by deforestation and overcultivation and leads to land degradation, decreases in productivity, and, in the event of drought, short-term collapse. Another—adaptive in the long run—is based on flexible land use, economic diversification, integrated agroforestry-livestock management, and intensive use of wetlands. This pattern tends to generate sustainable, intensive systems and is resilient in the face of drought.

Indigenous strategies of response to acute food shortage apparently enabled the Sahelian populations to survive notwithstanding the tardiness, inadequate scale, and maladministration of most relief programs. These strategies, which relied on economic diversification, such as using labor in urban areas to supplement agricultural income, have evolved in an environment of climatic uncertainty and confer a degree of short-term resiliency. Their future evolution is hard to predict. Continued integration into the world economy may improve roads and other infrastructure, thus enabling diversification; it may also increase pressure for development of cash crops and thus hasten land degradation.

Relationship of Policy to Indigenous Response Systems

The ability of indigenous systems of land use and crisis management to cut the link between drought and famine depends on various factors that sustain the indigenous systems. These include diversity of economic opportunities, absence of war, and appropriate national and international policies on migration. Critical variables include the development of infrastructure and the set of national policies governing access to land, trees, and water. The social distribution of wealth, particularly secure rights of individual or community access to natural resources, determines the extent of human vulnerability to drought. Although some impor-

tant international actors are coming to perceive these relationships, the political balance is quite different at the national level, where the relevant policies are enacted and enforced. Ruling and military elites, professionals in the civil service, traders (especially in grain), capitalistic farmers, livestock owners, wood fuel exploiters, and small farmers and herders all have separate and distinct interests in the outcome, and most of these interests do not accord high priority to sustainable environmental management or drought preparedness.

Although not enough is known to forecast the consequences of future Sahelian droughts, two alternative scenarios can be imagined. In the doomsday scenario, increasing numbers of people generate cumulative environmental degradation (overcutting of woodland, overcultivation of soils, overgrazing of pastures, and overirrigating and possibly overuse of water), suffer increasing food scarcities as available grain per capita declines, and either starve in huge numbers or migrate in distress to other areas where they become permanently dependent on international relief. In the optimistic scenario, farming systems intensify using an increased labor supply, productivity of the land is raised, sustainable agroforestry-with livestock systems are extended, and household income sources are diversified and slowly shifted via the market and short-term mobility away from agriculture and toward other economic sectors.

The experience of the 1970s and 1980s suggests that the optimistic scenario is a plausible alternative, given the right policy environment. Its success depends on increased recognition of the potential of indigenous sociocultural systems of land use and household strategies of economic diversification to increase resilience, and on policies that promote resource access and support those local social systems. The consequences of future droughts may also depend on rates of urbanization, growth of the urban informal sector, and capital investment in better favored rural areas. The present policies of governments and international organizations in the Sahel can create conditions that promote or impede the ability of indigenous systems to respond and thus determine the human consequences of future drought.

SEVEN HUMAN SYSTEMS

This section distinguishes seven human systems that may be affected by, and respond to, global change: individual perception, judgment, and action; markets; sociocultural systems; organized action at the subnational level; national policy; international co-

operation; and global human systems. It briefly surveys current knowledge and ignorance about the responses of each system and the relationships between them and identifies broad areas in which additional research is needed. It also outlines particular research activities and needs within these areas.

I NDIVIDUAL P ERCEPTION , J UDGMENT , AND A CTION

The human consequences of global change begin with the individual. Individuals notice the effects of change and either make adjustments or not. Individual behavior is critical in three quite distinct ways: individual judgments and choices mediate responses in all human systems because decision makers begin with inputs from individuals, whether themselves or their advisers. The consequences of global change often depend on the aggregation of the uncoordinated actions of large numbers of individuals. And individual behavior can be organized to influence collective and political responses.

Individual Judgment and Choice

Responses to global changes presuppose assessments of "what is happening, what the possible effects are and how well one likes them" (Fischhoff and Furby, 1983). 12 Scientists, government officials, and other citizens make such assessments when they consider the responses they may make or advocate. Knowledge about human judgment and decision is therefore relevant to understanding responses to global change.

Normative decision principles, such as those of cost-benefit analysis or mathematical decision theory, are limited in their usefulness by the fallibility of the individuals who try to implement them (Fischhoff, 1979); they are even more imperfect for estimating the behavior of people who are not trying (Fischhoff et al., 1982). Past research on human judgment and decision has clarified many differences between decision theory and actual decision making (Kahneman et al., 1982); some of these are reflected in human responses to natural hazards (Saarinen, 1982; Slovic et al., 1974).

Behavioral decision research demonstrates that most people have difficulty comprehending the very low probabilities assigned to environmental disasters (Slovic et al., 1977; Lichtenstein et al., 1978), estimating the probability of natural events that they rarely experience (Slovic et al., 1979), interpreting uncertain knowledge, and making connections between events and their actual causes.

Moreover, it is difficult or impossible to understand unprecedented events and therefore to make wise choices between mitigating them and adapting to them. One result is that lay people frequently perceive environmental hazards differently from specialists (Saarinen, 1982; Fischhoff and Furby, 1983; Gould et al., 1988; Fischhoff, 1989; Kempton, 1991). Little direct knowledge exists, however, on perceptions of climate, climate change, or other aspects of global change (Whyte, 1985; Kempton, 1991; Doble et al., 1990).

Behavioral research also raises questions about expert judgment. Expert analyses, such as represented in general circulation models of climate, inevitably rely on judgment, and judgment becomes more unreliable when the models move into a future different from any past experience. Faith in expert judgments rests on the analysts' success in identifying all the relevant variables and measuring them and their interrelations. Psychological research suggests that people, including technical experts, "have limited ability to recognize the assumptions upon which their judgments are based, appraise the completeness of their problem representations, or assess the limits of their own knowledge. Typically, their inability encourages overconfidence" (Fischhoff et al., 1977; Kahneman et al., 1982). Overconfidence is most likely to affect expert analysts when they lack experience testing their predictions against reality—an inevitable characteristic of predictions about unprecedented events (Fischhoff, 1989). Other kinds of systematic error may also affect experts. For instance, in water resource management and other fields in which average climate parameters are used as a basis for decision, experts seem to exhibit a "stability bias," a tendency to underestimate the likelihood of extreme events (Riebsame, 1987; Morrisette, 1988).

Careful analysts also sometimes overlook or underestimate the likelihood of some possible combinations of events, as they did in a famous assessment of the likelihood of nuclear power plant failure in the 1970s (Nuclear Regulatory Commission, 1978). Little is known about how individuals or groups formulate alternative action plans when faced with a problem, such as responding to a global environmental change. In particular, little is known about what facilitates or impedes creative generation of options, or how vested interest or attachment to the status quo may blind individuals or groups to available options.

Research Needs Research on what and how nonexperts think about particular global environmental problems can help estimate how individuals will respond to new information about the global

environment and identify their information needs. This research should address particular beliefs about global change as well as how people evaluate probabilistic and uncertain information and how they combine multiple bits of information from experts, mass media accounts, and personal experience (e.g., with recent weather or air pollution events) to form their judgments about the extent and seriousness of global environmental problems. Such research will require both intensive methods of interaction with informants and survey methods.

Research effort should also be devoted to studying the expert judgment of environmental analysts about global change. This research should address such questions as: Does professional training encourage or discourage particular misperceptions? Does it lead purportedly independent experts to share common preconceptions? How well do the experts understand the limits of their knowledge? Do estimates of the human effects of global change take into account feedbacks among human systems? In analyses of possible responses, what responses are likely to be omitted? To whom do experts turn for analyses of feasibility of responses? What implicit assumptions about human behavior guide the analyses? With preliminary answers to such questions, it is possible to estimate the sensitivity of analyses to variables that affect expert judgment and therefore to make better informed interpretations of these judgments.

Aggregated Individual Responses

The consequences of global environmental change often depend on the aggregated responses of very large numbers of individuals. The example of U.S. energy conservation shows the effect of millions of decisions to buy more fuel-efficient automobiles, reset thermostats, and reinsulate buildings; millions of consumers also drove down sales of aerosol cans when the news got out that they were releasing CFCs harmful to the ozone layer (Roan, 1989). Action to block UV-B radiation from the skin of a billion light-skinned people would similarly take many discrete actions by each of them.

As U.S. energy conservation efforts demonstrate, such individual actions are multiply determined. Financial considerations motivate action, but structural constraints limit action (for instance, not owning the home one would like to insulate); personal attitudes and values increase the likelihood of taking actions that fit the attitudes, subject to the other constraints; specific knowledge

about which actions would produce desired effects is helpful, but people often fail to seek it out or mistrust the information available (for reviews of relevant research, see Katzev and Johnson, 1987; Stern, 1986; Stern and Oskamp, 1987). Knowledge has been developed about the conditions under which individuals respond favorably to information (Ester and Winett, 1982; Dennis et al., 1990) and incentives (Stern et al., 1986a) in the context of residential energy conservation; more limited research has been done on other individual actions relevant to global environmental changes.

Research Needs At least three kinds of research should be pursued further to improve understanding of how individual behavior may be significant in response to global change. First is empirical research on the actual responsiveness of behavior to interventions believed to affect it. Energy conservation programs have often produced less than the predicted effects—but as already noted, the responses have been highly variable. For studying possible interventions to mitigate or adapt to global change, pilot studies and controlled evaluation research are particularly important (for a discussion of issues of method in the energy conservation context, see Stern et al., 1987).

Second, new research is warranted to determine the relative contributions and interactions of the various influences on particular individual behaviors implicated in global change (e.g., Black et al., 1985). This research should be interdisciplinary because, in most instances, behavior is jointly determined by technical, economic, psychological, and social variables in ways that are likely to differ as a function of the behavior and the societal context.

Third, research should be conducted to build an improved interface between behavioral studies of resource use and formal models, which are guided mainly by economic assumptions. Empirical analysis of the behavioral processes underlying descriptive categories such as price elasticity, implicit discount rate, and response lag is likely to add to understanding of human responses to price stimuli and government intervention, and also to encourage needed dialogue between economically and psychologically oriented analysts of consumer behavior (Stern, 1984, 1986).

Individuals as Social and Political Actors

Individuals, appropriately mobilized, can be powerful actors at the community and national levels. Individual perception and judgment determines support for social movements, such as the

environmental movement, that affect human response by linking individuals to the concerted actions of government and industry. Those actions, in turn, influence individual behavior both directly and through their effects on markets. Individual reactions, in the aggregate, determine the public acceptability of policy alternatives being considered for response. And secular changes in individual attitudes and values, such as about the importance of material goods to human well-being, may have great effects on the long-term response to global change.

Past research has investigated the correlates of environmental concern and related attitudes (e.g., Borden and Francis, 1978; Van Liere and Dunlap, 1980; Weigel, 1977) and tracked the rise of postmaterialist values in the United States and other Western democracies (Inglehart, 1990). Such attitudes have been strong and persistent in many countries since the 1970s. Other research has been devoted to the rise of the environmental movement and to its objectives and tactics (see below).

Research Needs There are important gaps in the literature. New research should carefully assess alternative hypotheses about the links between individuals' values and attitudes and their representation in the activities of environmental movement groups and other institutions involved in response to global change. For instance, the view that environmental organizations reflect widespread attitudes should be tested in the global context against other views, for instance that social movement activists act as entrepreneurs, with their own interests separate from those of the public they claim to represent (e.g., Touraine et al., 1983; Rohrschneider, 1990).

Future research should also address the bases of environmental concern. Such concern may derive from a new way of thinking about the relationships of humanity to the planet (e.g., Dunlap and Van Liere, 1978) or from concern about harm done to people, such as those indirectly affected by market transactions and those yet unborn (Dunlap and Van Liere, 1977; Heberlein, 1977; Stern et al., 1986b). Outside the U.S. context, yet other bases of concern may predominate. For instance, in several Soviet republics, the environmental movement of the late 1980s expressed demands for autonomy by smaller nationality groups against the dominant Russians. On another dimension, environmental concern may derive from personal experience or secondhand accounts in the mass media. The source of concern may determine the conditions under which people become aroused about a global change or recep-

tive to policies that take meaningful action but require additional costs. The determinants of concern are likely to vary with the environmental problem, the country, and characteristics of the individual, so the research should be comparative between countries and environmental problems of different kinds.

One of the most likely consequences of global change will be effects on the prices of important commodities and factors of economic production in local and world markets. As a result, uncoordinated human responses will be affected greatly by markets. According to economic theory, producers and consumers respond to changing relative incomes, prices, and external constraints, so that, if the market signals are allowed to reach individuals and market prices include all the social costs and benefits of individual actions, the responses will be relatively rapid and efficient.

Markets allow for many forms of uncoordinated adjustment, as the example of climate change illustrates. People may rapidly alter patterns of consumption (e.g., substitution of water skiing for snow skiing) and production (e.g., relying on snowmaking equipment rather than natural snowfall). Over the longer run, societies may respond, in the case of unfavorable climatic developments, with the migration of capital and labor to areas of more hospitable climates. Structures tend to retreat from the advancing sea, people tend to migrate from unpleasant climates, and agricultural, sylvan, and industrial capital tend to migrate away from lands that lose their comparative advantage. In addition, technology may change, particularly in climate-sensitive sectors such as agriculture and building.

However, the conditions that economic theory specifies for efficient adjustment are not generally met in the case of the global environment (Baumol and Oates, 1988). In three important respects, existing markets do not provide the right signals (in the form of prices and incomes) of social scarcities and values. And in addition, as already noted, the participants in markets do not always behave as strict rules of economic rationality predict.

Environmental externalities of economic activity, that is, effects experienced by those not directly involved in economic transactions, are not priced in markets today. Someone who emits a ton of carbon into the atmosphere may produce great damage to the future climate but does not pay for the damage: effects that

have no price may be treated as if they have no value. Similar problems arise with the externalities of deforestation, CFC emissions, and other environmental problems. Economic theory recognizes that when there are significant externalities, uncoordinated responses will be inappropriate because the market does not transmit the right signals. An additional problem concerns making tradeoffs when each response option produces different externalities (Fischhoff et al., 1981; Bentkover et al., 1985; Mitchell and Carson, 1988; Fischhoff, 1991).

The market mechanism is overridden at times, either by political systems (such as when countries set the prices of oil or coal well below or above world market levels); or because custom and tradition determine property rights in a way that precludes the emergence of markets, as in the case of water allocation in the western United States. In such cases, individuals are either not faced with prices at all or are faced with prices unrepresentative of true social scarcities, and their uncoordinated behavior will not achieve the rapid and efficient adjustments characteristic of free markets.

Discount rates in markets, such as interest rates, reflect a social time preference for the present over the future that does not correspond to social valuation of the distant future reflected in concern about problems of global change (Lind, 1986). For events a century in the future, a discount rate that is, say, 3 percent per annum higher than true social preference implies that the future events are valued at only one-twentieth (that is, 1.03-100) of their appropriate value. Market interest rates may be too high to reflect this generation's concerns about the future of the environment; vigorous debate exists about whether the concept of discounting is even moral when human life is at stake (MacLean, 1990). Uncoordinated decisions following such a discount rate undervalue future threats and opportunities.

Economic theory suggests prescriptions for government action when market signals do not correspond to social values. The goal usually considered most important is to get the environmental impacts reliably translated into the price and income signals that will induce private adaptation. But it is difficult to arrive at the "correct" prices because so many of the impacts of global change are unknown or uncertain and because the appropriate values of future events are unlikely to be the same from all generational vantage points and resource endowments (Lind, 1986; Pearce and Turner, 1990).

Economists have suggested some approaches to the problem of developing well-functioning markets to guide responses to global

change (for some examples, see Pearce and Turner, 1990 and Dasgupta and Heal, 1979). Theory suggests that governments intervene with policies that meet at least one of these criteria: (1) they have such long lead times that they must be undertaken now to be effective; (2) they are likely to be economical even in the absence of global change; or (3) the penalty from waiting a decade or two to undertake the policy is extremely high. These criteria suggest four kinds of intervention, which we note here.

Government may encourage quasi-market mechanisms before shortages occur. For example, to ensure that water will be efficiently allocated if climate change affects its availability, governments might introduce general allocational devices, such as auctions, to dispatch water to the highest-value uses. The same approach might be applied to allocate land use near sea coasts and in flood plains and to control pollution by auctioning pollution rights. Governments might also support systems of risk-adjusted insurance for flood plains or hurricanes or international climate insurance. These quasi-market mechanisms have both the advantages and the disadvantages of the market. They make allocations efficiently but tend to undersupply goods needed by those who do not participate effectively in the markets, such as people outside the geographical boundaries of a quasi-market, who may receive polluted air or salinated water.

Government may support research and development on inexpensive and reliable ways of slowing or adapting to global change. Research on adaptation is undersupplied by markets because inventors cannot capture the full fruits of their inventions. Research on mitigation technologies that will slow global changes are even more seriously undersupplied in markets, because not only can inventors not collect the fruits of their efforts, but also the fruits, such as preservation of climate, are unpriced or underpriced in the market.

International agreements may provide for international adaptation strategies, such as improved international markets, which allow migration of labor and capital over a greater geographical range than national markets.

Governments may promote needed knowledge and collect and distribute data about global change, to enable rational response. It is difficult for people to mitigate or adapt if they do not understand what is happening or the costs of the available responses and of inaction; costs of adaptation will be reduced to the extent that managers, diplomats, and voters are well informed about well-established scientific results.

Research Needs Although the above market-oriented response strategies are strongly supported by economic theory, knowledge is weak about how they may be effectively implemented. Three lines of research into markets can add to understanding of the available response strategies.

First, empirical studies are needed of the implementation of quasi-market mechanisms for adaptation to global change, to determine how particular mechanisms work in particular social and political systems. For instance, systems for auctioning emission rights can be made infeasible by political opposition, subverted by fraud, undermined by political decisions, or otherwise altered from their theoretically pure operation (Tietenberg, 1985, explains the principle in the case of local air pollution; application to global change would be more difficult). Retrospective and prospective studies of the operation of such mechanisms can illuminate the problems that arise in implementation and assess the actual, as opposed to theoretical, effects of such mechanisms on equity and efficiency. Such assessments should compare quasi-market mechanisms to available regulatory mechanisms, as each actually operates (see the section below on national policy).

Second, studies of the valuation of global environmental externalities are critically important to address several key questions. For instance: To what extent can knowledge or technology be substituted for the outputs of environmental systems, thus making those outputs less indispensable? Is such substitution desirable? How can the ''services'' produced by the natural environment be included in economic accounting systems, such as national income accounts? How can the producers and recipients of externalities arrive at a common valuation if one side is disadvantaged in financial resources, and therefore in the ability to participate in markets or quasi-markets? How do people value, and make tradeoffs between, different kinds of externalities? How do different actors value the effects of human interventions in the environment and make tradeoffs between effects? (Some of these questions are addressed in work by Mitchell and Carson, 1988, and Nordhaus, 1990.)

Third, studies of social discount rates are needed, especially to estimate preferences concerning the future environment so they can be included in evaluations of global environmental change (e.g., Lind et al., 1986). Many believe that market discount rates are too high to accurately represent the social value of the future environment, although this value is unknown.

S OCIOCULTURAL S YSTEMS

Between the uncoordinated activities of individuals and the formally organized activities of governments and international organizations lie the oldest forms of social organization: families, clans, tribes, and other social units held together by such bonds as solidarity, obligation, duty, and love. These sociocultural systems have undergone considerable change throughout human history, yet informal groups connected by these bonds still exist and the bonds still influence behavior independently of governments and markets. Sociocultural systems are important in terms of global change in two ways. Some long-lived social units, whose survival may be threatened by global change, have developed ways of interacting with their environments that may be adaptable by others as strategies for response. Also, informal social bonds can have important effects on individual and community responses to global change and on the implementation of organized policy responses.

Indigenous Sociocultural Systems of Adaptation to Environment

Indigenous peoples that were not tightly integrated into world markets have developed technological and social adaptations that often maintain their subsistence in reasonable balance with the local environment. The adaptations of Sahelian peoples to an environmental regime of recurrent drought is one example. A parallel example can be found in the indigenous economic systems on the Amazon, which for at least 500 years have used the ecosystem's material in ways that do not threaten its long-term productivity (Hecht and Cockburn, 1989). The Amazon's indigenous people are a major repository of practical environmental knowledge about sustainable use of resources (Moran, 1990; Posey, 1983). Slash-and-bum cultivation with adequate fallow periods allows for the recovery of vegetation in tropic moist forests (Uhl et al., 1989), attracts game animals to crops (Linares, 1976; Balée and Gély, 1989), and provides a well-balanced, varied diet (Baksh, n.d.). Local agroforestry systems, which combine "the production of crops including tree crops, forest plants and/or animals simultaneously or sequentially on the same unit of land" (King and Chandler, 1978), mimic tropical ecosystems, protecting the soil from leaching and erosion while replicating the natural succession of plant growth over a period of years, and are a model for modern systems of agroforestry. Some such systems can give per

hectare yields over five years roughly 200 percent higher than systems established by colonists and 175 times that of livestock (Hecht, 1989a:173).

Agricultural systems based on indigenous models can be profitable in a market economy. Japanese colonist smallholders in the Amazon have created complex systems that prevent soil degradation and tolerate soil acidity and aluminum toxicity better than annual crops. These systems involve polycultures of mixed perennial and annual crops that are transformed, over time, into polycultures of mixed perennials. Commercial quantities of black pepper, cacao, passion fruit, rubber, papaya, eggs, and pumpkins and other vegetables are produced (Subler and Uhl, 1990). Into this sustainable, intensive agroforestry system, the Japanese farmers often incorporate fish culture and chicken and pig production and use waste or refuse from one operation as inputs to other operations (Uhl et al., 1989).

The knowledge about environmental adaptation resident in indigenous social groups depends, of course, on the survival of these groups. Development strategies that destroy the forests can undermine the ability to mitigate or respond to global change by threatening local sociocultural systems based on sustainable, noninvasive strategies of using the land. In the Amazon, the newly expanding, extensive land uses are not compatible with indigenous Indian systems of gathering, long-fallow cultivation, fishing, and hunting and also threaten the subsistence of some 2 million small-scale extractors who collect rubber, nuts, resins, palm products, and medicines while practicing small-scale farming and foraging. Current issues in the Brazilian policy debate that will affect the viability of indigenous groups include the implementation of reserves on which these groups collectively determine resource exploitation (Hecht and Cockburn, 1989), institutions governing the enclosure of public land for unrestricted private uses, and various types of park or biosphere areas with protected wilderness and some degree of zoned multiple use (Poole, 1989:43).

Indigenous sociocultural systems that have adapted to highly variable environments may offer lessons for improving the robustness of social systems to environmental changes outside of past experience. The adaptation in the Sahel points to the importance of diversified sources of cash and subsistence in allowing local groups to adapt to environmental change with limited human cost. An instructive counterexample may be the American Great Plains, where a new generation of settlers between the 1890s and 1920s developed an agricultural system poorly adapted to the area's vari-

able rainfall patterns. The limited adaptability became obvious in the Dust Bowl period of the 1930s. The results included large-scale out-migration and the development of a national system of governmental supports for regional agriculture that encouraged the remaining farmers to further expand their use of limited water supplies. Some analysts believe these changes brought the farmers' adaptability without continued outside assistance into even more serious question (Worster, 1989). Other recent research, however, argues that the serious drought of the 1950s did not have devastating effects and suggests that a recurrence of the climate of the 1930s in the Great Plains would have little effect on the region's agriculture (Rosenberg et al., 1990).

Research Needs Research on intensive, sustainable agricultural systems can help identify and evaluate viable alternatives to development strategies that have resulted in deforestation and land degradation in the tropics. Such research can help develop strategies that may provide subsistence and cash for rural populations but that do not afford the high returns to labor and to speculative activities of unrestricted, extensive land use (Moran, 1990).

Research on systems of land use in variable environments can help identify the characteristics of some of these systems that allow them to take environmental change in stride. Such research can identify anticipatory policies that may enable local or regional social systems to withstand the local effects of global environmental changes at low cost, with limited demands on disaster response systems.

Social Bonds and Responses to Environmental Change

Individual behaviors in response to global change are also affected by informal social influences. People imitate individuals they like or respect, follow unwritten norms of interpersonal behavior, and preferentially accept information from sources they trust (Darley and Beniger, 1981; Brown, 1981; Rogers, 1983; Rogers and Kincaid, 1981).

Such influences are significant factors in social response to natural disasters, particularly those that strike quickly and with little warning, such as floods and major storms (White, 1974; White and Haas, 1975; Burton et al., 1978; Riebsame et al., 1986; Whyte, 1986). Studies of community responses to disaster show that family and acquaintance groups and community organizations are often the focus of behavior (Dynes, 1970, 1972), and that spon-

taneous improvisation at the local level—often by nongovernmental groups—has been a key to effective response (Barton, 1969; Quarantelli and Dynes, 1977). These findings are relevant to global climatic change in that the consequences of such change are likely to include a shift or increase in the incidence of just such natural disasters.

Informal social links are also significant influences on the acceptance of mitigation strategies, such as energy conservation programs aimed at individuals and households (Stern and Aronson, 1984). Adoption of new, energy-efficient technology tends to follow lines of personal acquaintance (Darley and Beniger, 1981), and participation in government energy conservation programs is higher when the program takes advantage of personal acquaintanceships and local organizations with good face-to-face relations with members of the target group (Stern et al., 1986a).

Research Needs Efforts to develop policy responses in anticipation or response to global change will benefit from knowledge of sociocultural systems of social influence. Research efforts can profitably focus on understanding the social networks, norms, and influence patterns of groups that are highly likely to suffer from anticipated environmental change, so that policies can be designed to work with rather than against these lines of influence. Policy studies should focus on ways to directly involve affected groups, and should compare implementations of the same policies with and without such efforts.

O RGANIZED R ESPONSES O UTSIDE G OVERNMENT

Three kinds of social actors other than governments may make significant, organized responses to global change: communities, social movements, and corporations and trade associations. These collective actors form a vital link between behavior at the level of individuals, firms, and households and at the level of institutions and nations.

Communities

A community is more than a shared place of residence. It is also a unit in which people earn their living, engage in political activity, raise their children, and carry out most of their lives. Community responses to the stresses of environmental change occur both in the uncoordinated ways discussed in the previous

section and through organized activity. Decades of research on economic development in rural areas suggests that the full impacts of major social changes, including those that may be induced by environmental change, can be understood only by considering the effects of such changes on communities, as well as on individuals and institutions (e.g., Field and Burch, 1988; Machlis and Force, 1988; Machlis et al., 1990).

Communities are likely to respond in different ways to the local impacts of global environmental change. Some communities are sufficiently diverse to provide valuable buffers against hardship as individuals and households share resources. But if all members of the community use the same environment in similar ways, no such buffering is possible. Traditional relationships and patterns of action, tension, and rivalry within a community may help the community through crisis, or may prevent organized action that would help the community cope with or take advantage of local changes. And if local manifestations of global change disrupt traditional patterns of community life, they generate stress and conflict that can become violent.

Of course, the character of community life continues to change in much of the world. With the rapid growth of urban and suburban areas in the developed and especially the developing world, the historical links among home, polity, and economy are greatly weakened. The spheres in which individuals and households act become more disjunct and less well integrated. Global environmental change may increase the pace of this historical trend if it makes rural agricultural life more difficult and thus increases the migration to urban areas, with consequences for the ability of communities, particularly in the Third World, to withstand further environmental change.

Research Needs Research is needed on those characteristics of communities that affect their organized responses to global change. For example, in the United States, the spatial character of suburban communities is a significant barrier to increased use of public transportation. Yet some suburban communities and small towns have been vigorous in their implementation of environmental and energy and water conservation policies (Dietz and Vine, 1982; Berk et al., 1980; Vine, 1981). The response of those communities seems to be greater than would be expected from aggregated simple self-interest or the technical response to changes mandated by policy. The community amplifies individual action, perhaps by creating a sense of identity and trust that overcomes the usual

collective goods problem. Especially in the less-developed world, effective community response may depend on the community's access to a variety of resources that can be used to dampen adverse changes in any single resource. In addition, adaptation by individuals and households may be conditioned by the diversity and flexibility of the community, which are in turn affected both by the natural environment and the local political economy, history, and culture. Research is also needed on the conditions controlling the differential effectiveness of environmental and energy programs in different communities.

Social Movements

Environmental movement organizations have been major actors in debating national and even international responses to global change (also see the section below on national policy). The broad awareness that global changes are occurring is in large part due to various national environmental movements drawing attention to the growing body of scientific evidence on the subject.

Most of the national activity of environmental movement organizations is intended to change public policy. How environmental groups influence policy depends on the political context in which they operate, and in particular on the relationship between the movement and political parties. In political systems in which it is difficult to achieve participation via a small party, such as the United States, movements have only loose alliances with political parties. In systems where small parties can play a serious role in influencing policy, the movements either form tight alliances with parties or act as parties in themselves. These structural differences affect movement strategy and have produced some sharp differences in how environmental problems are conceptualized. The ways political structure affects the political impact of the environmental movement on policy have not been studied in enough detail to offer generalizations.

Whatever their relation to political parties, environmental groups usually find themselves in conflict with corporations, trade associations, and often with government officials. Each side brings a different mix of resources to the conflict. In the United States, environmental groups seem to have a high degree of public support and strong legitimacy with other actors in policy debates (Dietz and Rycroft, 1987). Corporations and their representatives have far greater financial and personnel resources, but less public support and less legitimacy within the policy system. Govern-

ment falls between the two. The difference in resources means that each group will struggle not only over the substance at issue, such as a specific policy, but also over the definition of the problem and the kinds of resources that are legitimate for resolving the problem (Dietz et al., 1989). The difference in resource distribution has typically led industry to favor heavy reliance on scientific analyses and technologically driven policies, and led environmentalists to be more skeptical of those alternatives and inclined to favor source reduction and infrastructure changes.

Modern environmental groups play an important role in shaping public values and consciousness. Indeed, some students of the movement have suggested that its primary goal is to change ways of thinking rather than specific political choices (Cohen, 1985; Eder, 1985; Habermas, 1981; Offe, 1985; Touraine, 1985; Touraine et al., 1983). The rise of "green" ideologies in the United States, Western Europe, and throughout the world seems to reflect changes in consumer preferences and lifestyles that may have important implications for individual, household, and community response to global change (Inglehart, 1990).

Research Needs A number of important questions need to be answered about the role of the environmental movement in responses to global change. How do the strategies pursued by environmental movements in both the developed and less-developed nations influence the character of national policy? What impacts do these influences have on the ability to reach international accords? How does environmentalism interact with scientific research on global change, and what could be done to produce better interactions? How much change in individual ideology is brought about by the environmental movement, and how do these changes affect the behavior of individuals, households, communities, and other actors? What is the likely character and influence of the environmental movements that are emerging in Japan, Eastern Europe, and less developed nations and what role will they have in shaping national and international response?

Corporations and Trade and Industry Associations

Corporations and trade and industry associations are major actors shaping response to global change. Just as the environmental movement translates public concern into political action and in turn shapes public perceptions and actions, corporations and trade associations translate the interests they represent into political

positions and also educate those connected to them. As already noted, these groups come to the policy arena with very different resources than environmental groups and, in general, tend to favor different methods for analyzing environmental problems and different strategies for solving them (Dietz and Rycroft, 1987; J.R. Wright, 1990).

Research Needs The relationships of corporations and trade associations to national policy systems, critical for understanding policy response, are discussed in the next section. The internal aspects of these collectivities, however, are little studied. Corporations communicate with each other, and trade associations are influential in shaping the response of corporate members, two processes that shape the policy positions of the business community. Research is badly needed on how corporations and trade associations attempt to communicate internationally about global environmental issues with other groups representing the same industries.

N ATIONAL P OLICY

Nation-states help determine the consequences of global change through their essential role in international agreements and by national policy decisions that affect the ability to respond at local and individual levels. This section focuses primarily on two issues: differences between nations in their environmental policies and the policy process.

National Differences in Environmental Policy

National environmental policies vary in part because of different public attitudes. People around the world have shown concern with the environment, but the intensity and focus of interest have varied from country to country. Some observers claim that during the early 1970s, environmental issues were much more politically salient in Japan and the United States than they were in Europe; during the 1980s, the reverse has been true (Vogel, 1990). Such variations may be a function of national economic performance, actual environmental quality, or national political cultures. The focus of environmental concern in Japan has been claimed to be on the protection of public health, while in Germany the protection of nature has been accorded much higher priority, with the United States and Great Britain falling some-

where in between (Vogel, 1990). These differences, which may be more or less stable over time, are likely to have important implications for different nations' responses to various kinds of global environmental issues.

Policies also vary because each nation's political system responds to public concerns in its characteristic way. Within democratic nations, many political features vary. Nongovernmental organizations concerned with environmental improvement are not equally well organized in all countries. Citizens of different nations display different propensities to join voluntary organizations concerned with environmental improvement, and these organizations do not have similar access to the policy process everywhere. The United States, with its constitutional system based on the separation of powers, provides nongovernmental organizations with substantial opportunities to shape public policy through access to the courts and the national legislature. By contrast, more centralized political systems, such as France and Japan, severely restrict participation by citizens' groups. Parliamentary systems that have proportional representation, such as in Germany, provide access to the political system by facilitating the formation and representation of political parties committed to environmental improvement (see Parkin, 1989).

Policy systems also vary in the response of major affected interests, particularly those of business. Most environmental problems, domestic as well as global, require substantial changes in what firms produce and how they produce it. To the extent that these changes increase costs, businesses are likely to oppose them and the changes are unlikely to occur. Business resistance can be reduced if new technology enables firms to behave in ways that are environmentally benign without increasing their costs, if consumers develop a "green" consciousness that opens new markets, or if government offers subsidies. As a rule, environmental policies are more likely to be effectively implemented to the extent that investors and managers in some industries and firms believe they can benefit financially.

These issues extend beyond business. Environmental regulations do not simply impose additional burdens on producers; they also affect the relative welfare of consumers, employees, and taxpayers. These burdens may be primarily nonmonetary or monetary, concentrated or dispersed, and relatively visible or invisible, but in all cases they have important political consequences. There is a relevant body of research on how interest groups respond to different kinds of expected burdens and benefits, at least

in the United States and a few other countries (Leone, 1987; Meiners and Yandle, 1989).

Environmental policy systems vary in many ways in their approaches to regulation (e.g., Tarlock and Tarak, 1983; Mangun, 1979). Regulations may control emissions at the source, by establishing environmental quality standards, or by establishing exposure standards. Each strategy has various strengths and weaknesses (see Haigh, 1989). Environmental regulation can be coordinated by a single regulatory body or dispersed among a variety of regulatory authorities; relatively centralized in the national government, as in Great Britain, Japan, and France, or administrated primarily by local governments, as in the Federal Republic of Germany. Regulation can be anticipatory, requiring firms to get permission before they can act, as with mandatory environmental impact assessments, or may take place after the fact. And there are different national styles of regulation (Vogel, 1986). The United States has developed an adversarial regulatory style, in which government establishes ambitious and highly specific standards and frequently tries to impose legal penalties for noncompliance. Great Britain, by contrast, uses an approach to regulation characterized by more flexible standards, modest goals, very infrequent use of legal penalties, and restricted participation by the public and environmental groups.

Scientists and scientific evidence play very different roles in different countries' environmental policies. The United States is unusual in providing opportunities for diverse groups of scientists to affect regulatory policies. By contrast, participation by scientists in Europe is more likely to be confined to official channels. The United States is also unusual in having regulatory decisions tied by statute to the outcomes of risk analyses. Thus, it is sometimes easier to have a product or production process banned or restricted in the United States than in most other capitalist nations (see, e.g., Brickman et al., 1985).

Research Needs Most of the sources of variation mentioned apply not only to environmental policies but also to national-level policies in many other areas that can have significant effects downstream. Research is needed to assess the effects of national macroeconomic, fiscal, agricultural, energy, economic development, and science and technology policies on global change and on the ability to respond to global change. These effects are much less well researched than the effects of environmental policy.

Cross-national research comparing the determinants of national

environmental policy, focused especially on responses to global change and on the sources of policy differences between countries, is also needed. This research should assess the effects of influences such as public opinion, environmental movement organizations, and various organized interest groups, as well as structural features such as democratic versus nondemocratic politics, market versus centrally planned economies, relative wealth, scientific and technical resource base, and position in the world political-economic system (studies of this type, not focused on responses to global change per se, include Brickman et al., 1985; Jasanoff, 1986; Vogel, 1986; and Jasper, 1990). Such research can help clarify the kinds of policy options that are viable in different countries, which is a factor in reaching and implementing international agreements. In particular, it is important to understand the conditions under which nations enact policies promoting the development of environmentally benign technologies because such development, while it could produce large benefits on a global scale, is often unlikely to come from the private sector because of the difficulty of appropriating profits.

Research should also assess the impact of environmental regulation and alternatives to regulation cross-nationally and across policy questions to clarify how, why, and under what circumstances different regulatory or other strategies work in different policy settings. Such research should proceed despite the lack of clear standards for comparing the effectiveness of the environmental policies of different governments. Every indicator has both strengths and weaknesses. For example, emissions and environmental quality are affected by many factors other than policy, including topography, the nature of industrial production, and the rate and location of economic growth. Likewise, expenditures on abatement by industry are an imperfect measure of the effectiveness of regulation because they may or may not represent a net economic burden. The useful literature on policy compliance and effectiveness is largely confined to a handful of countries and policies (e.g., Bardach and Kagan, 1982; DiMento, 1989).

Finally, research should compare the institutions used in different countries to manage conflict over environmental policy. These institutions are both formal (e.g., legislative and regulatory proceedings and court decisions) and informal (e.g., lobbying, use of publicity in the mass media), and they deal with substantive disagreements, formal procedures, and disagreements about the nature of knowledge about global change and the likely impacts of policy choices. Distinctive national systems of conflict manage-

ment can be identified and compared; each probably generates characteristic patterns of conflict and characteristic difficulties in decision making.

The Environmental Decision-Making Process

The consequences of global change depend on decisions made in government agencies and other large organizations. Knowledge about the decision process in such organizations is therefore potentially relevant to responses by both governmental and nongovernmental organizations. Specialists on decision processes, a field that makes no sharp distinction between governmental and other complex organizations, typically distinguish analytically among phases of the process, such as understanding the phenomena, identifying viable options, and selecting an alternative.

Government agencies involved in responding to global change rely on information from experts to gain understanding, but they must make it useful to their leaders, who are almost always non-experts, and must interpret the conflicts between, and uncertainty within, expert judgments. There is a general body of literature on the ways government agencies and other large organizations acquire and process expert knowledge (e.g., Lindblom and Cohen, 1979; Weiss and Bucuvalas, 1980) and on the inherent problems of informing nonexpert decision makers about uncertain and disputed scientific knowledge (National Research Council, 1989b).

Organizations can generally identify a large number of options, but they tend to funnel information to narrow the universe of issues or action alternatives presented to leaders (March and Olsen 1989). Similarly, not all options known to a society reach its legislative agendas (e.g., Kingdon, 1984). Among the factors involved in getting environmental issues on political agendas arc mass media coverage of disastrous or telegenic events and threats, of dread consequences such as cancer, danger to children and future generations, the characteristics that increase perceived seriousness of risks among most citizens (Mazur, 1981; Sandman et al., 1987; Rosenbaum, 1991). Government action on environmental hazards is typically driven by crises, with major events evoking bursts of legislation (May, 1985; National Research Council 1987). It is less clear, however, how particular response options, get on the agendas of government agencies or other organizations

Decisions within government agencies and other large organizations are affected by standard operating procedures, preassigned divisions of labor, accounting systems, organizational cultures

bureaucratic politics, organizational hierarchy, bargaining and negotiation processes, leadership practices, and the control of information by constituent individuals and subunits with goals only partly coincident with those of the organization as a whole (Seidman and Gilmour, 1986; March and Olsen, 1989). Decisions are influenced by relationships between organizations, for example, in international environmental agreements, interagency negotiations, lobbying coalitions, and even large industrial firms that must weigh the positions of their marketing, manufacturing, engineering, and legal departments in deciding whether to change to a more environmentally benign manufacturing process. Decisions are also affected by the structure of institutions—the systems of rights and rules that constrain the actions of individual parties. Examples include the effects of such institutions as markets for land and energy, land tenure systems, the law of property rights and torts, representative government, and international regimes (discussed in the next section).

Research Needs The organizational decision-making perspective points to a number of areas in which the general concepts in the field might be usefully applied to organizational actions affecting response to global change. For instance, informative studies could be done on how organizational understanding of environmental issues develops; how intraorganizational factors affect the responses of corporations, government agencies, and national political systems to global change; and how bargaining, rivalries, informal norms, and other processes of influence between organizations affect organizational responses to global change. An area of more pointed interest is the comparative study of environmental decisions in different institutional contexts. To gain understanding of the consequences of global change, it is important to understand the effects of different systems of land tenure on deforestation, of different national regulatory systems on the control of atmospheric pollutants, and of different systems of property rights in subsurface resources on policies to limit extraction of fossil fuels.

I NTERNATIONAL C OOPERATION

Sustained international cooperation is one essential element in the overall human response to global environmental changes. It is essential because efforts to cope with some large-scale environmental changes such as ozone depletion and global warming seem

doomed to fail if some of the major national actors do not cooperate. Recent agreements among the advanced industrial countries to phase out the use of CFCs cannot solve the problem of ozone depletion unless some way is devised to persuade China, India, and other developing countries to use substitutes for CFCs in their rapidly increasing production and consumption of refrigerants. The global warming problem is even more complex. Not only is there a need for cooperation between the advanced industrialized states and the major fossil fuel-using states of the developing world, but there is also the problem of controlling other sources of greenhouse gases. These sources are as diverse and widespread as methane-releasing agricultural activity in south Asian rice paddies and North American feedlots and carbon releases from cutting tropical forests in Zaire and Brazil.

Some environmental problems call for international action because activities in one country produce spillover effects or externalities affecting other countries. An example is the emission of airborne pollutants in the eastern United States and Eastern Europe. International cooperation is needed to articulate and apply liability rules or to allow the countries affected by spillover effects to compensate those responsible for the offensive emissions for terminating or redirecting their activities.

Today's concerns with international arrangements focus mainly on mitigating global environmental changes rather than adjusting to them. In the future, however, as global changes become realities, there will be more calls for international cooperation to adjust to the impacts, for instance, by developing buffer stocks of food crops or mechanisms to handle flows of environmental refugees.

International cooperation poses difficult problems, even when all the parties stand to gain from the right agreement. One of the most robust theoretical findings of the social sciences is that rational actors engaging in interactive decision making in the absence of effective rules or social conventions often fail to realize feasible joint gains, sometimes ending up with outcomes that are destructive for all concerned (Olson, 1965; Hardin, 1982). The conditions of international society make the problem more complicated than it is in other situations. The issues are seldom well defined at the start, so that preliminary negotiations may be needed to define them. When unanimity is required, some states can hold the agreement hostage to better terms for themselves. Each country is complex, and bargaining within countries can make international agreements especially difficult (Putnam, 1988). And

the agreement can take second place to more immediate issues in any of the countries involved.

Most observers now believe that the key to solving these collective-action problems is in the creation of international regimes, or more broadly, international institutions (Krasner, 1983; Young, 1989a). Regimes are interlocking sets of rights and rules that govern interactions among their members with regard to particular areas of action. Although most of the research on international regimes concerns economic regimes, interest is mounting rapidly in the study of environmental regimes, particularly the developing regime for the protection of the stratospheric ozone layer (Benedick, 1991), but also other, more geographically limited, international environmental regimes (e.g., Sand, 1990a; Haas, 1990).

The ozone regime exemplifies one model of regime formation, in which a framework convention is followed by a series of substantive protocols in quick succession. Another model sets out substantive provisions in more or less complete form in initial agreements. Cases in point include the 1946 International Convention for the Regulation of Whaling and the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora (Lyster, 1985). Additional study is warranted to determine the circumstances under which one or the other of these models is more appropriate.

Most of the research on environmental regimes has so far emphasized regime formation, particularly the determinants of success or failure in forming regimes and the timing and content of successfully formed regimes. This work has highlighted five sets of explanatory variables. One stream of analysis emphasizes structural aspects of the relationships involved in regime formation, such as the number of participants, the extent to which interaction is ongoing, and the nature of the mixed incentives to cooperate and compete (Oye, 1986). Another stream focuses on the role of power relationships, such as the presence of a hegemonic power, that is, an actor possessing a preponderance of material resources (Keohane, 1984:Chap. 3). A third stream emphasizes factors likely to impede or facilitate the negotiation process, such as the extent to which negotiations lend themselves to ''integrative bargaining,'' the thickness of the "veil of uncertainty," the impact of exogenous crises, and the role of leadership (Young, 1989b). A fourth stream emphasizes cognitive variables, such as the role of widely shared ideas (Cox, 1983) or an "epistemic community," that is, an international group of officials and scientists who share

a set of causal beliefs and a set of preferences for action (Haas, 1990). A final stream of research stresses the importance of the international context in providing windows of opportunity for agreements that are blocked at other times by resistances in one country or another.

Research Needs Knowledge is limited on several aspects of international agreement that are particularly relevant to problems of response to global change. One is the effectiveness of institutional arrangements, that is, the factors determining how strongly a regime affects the behavior of those subject to its provisions. Effectiveness is partly a function of implementation which, as at the national level, often leads to outcomes quite different from what a reading of the initial agreement would lead one to expect (Pressman and Wildavsky, 1984). It also depends on the degree to which arrangements are structured so that those subject to the regime comply voluntarily and do not have to be continually monitored and coerced. Finally, it depends on the ability of a regime to persist even after the constellation of interests that gave rise to it has changed or disappeared (Krasner, 1989).

Another area for new research concerns preparatory negotiations, aimed at reaching a common conceptualization of environmental problems. Many international issues that require cooperation are not ripe for negotiation because the issues have not yet been defined in a way suitable for bargaining (e.g., Stein, 1989; Saunders, 1989). This certainly seems to be the case for complex environmental issues, such as would be raised in drafting a comprehensive law of the atmosphere on the model of the law of the sea. National representatives would need first to identify packages of policies they might use to comply and assess the costs of those packages in terms of their interests. The process would be much more complex than establishing limited regimes to deal with ozone depletion or acid rain or establishing a series of regional regimes combined with agreements between regional groups.

A third area concerns the problems of regime formation when the participants are deeply divided. Many global environmental problems involve north-south confrontations in which the wealthy, industrialized states want to limit environmental changes but developing countries see limits as threats to their development. Examples include conflict between the desire to limit carbon dioxide emissions and energy needs in China and India, and between the desire to protect global biodiversity and plans for the use of forests in Brazil and Indonesia. Much needs to be learned,

for example, about the bargaining power of apparently weak players, like China, which can issue credible threats to step up their use of coal or CFCs unless others make it worthwhile for them to desist.

More knowledge is also needed about the role of nonstate actors, such as intergovernmental organizations, environmental movement organizations, and transnational corporations, in the creation and operation of environmental regimes. The involvement of such nonstate actors heralds the emergence of a more complicated international society in which states remain important but share influence with several other types of actors. This change may require more sophisticated conceptualizations of international interactions.

Finally, there is need for better understanding of the relationships between institutions (sets of rights and rules) and organizations (material entities with offices, staffs, budgets, and legal responsibility) (Young, 1989a, b). Organizations, such as the United Nations Environment Programme, have sometimes been important players in regime formation; they are sometimes necessary to manage regimes, although implementation of key rules is sometimes delegated to the member governments. Given the costs of operating international organizations, it is important to have a better understanding of the conditions under which they are necessary, or more effective than alternatives.

The above research agenda is relevant not only to the practical problems of responding to global change, but also to some basic issues in social science. The gaps in knowledge about international environmental regimes are also gaps in the broader literatures on social institutions and collective action. This global change research agenda would therefore be a direct and timely contribution to political science.

G LOBAL S OCIAL C HANGE

As we note at the opening of this chapter, the consequences of global environmental change depend on the future shape of human society. A number of ongoing changes in human systems, operating systemically or cumulatively at the global level, are shaping the societies that will feel the effects of global environmental change. Although global social changes are numerous, to our knowledge, a thoughtful typology of them has not been developed. As an impetus to further analysis and research, we note several examples of global social changes that may affect the driv-

ing or mitigating forces of global environmental change or the ability of human systems to respond to such change.

Population Distribution and Size The urban population of the world continues to increase both in total and in percentage terms, in both the developed and developing countries (Berry, 1991; Smith and London, 1990). Urbanization, by increasing spatial concentration, may increase vulnerability to natural hazards, concentrated pollutant emissions, and globally systemic changes such as sea-level rise. Urban bias in developing countries may also skew national priorities away from rural resource and environmental problems (Lipton, 1977). However, urbanization may decrease vulnerability by affording economies of scale in resource use and environmental protection, allowing rural households to diversify their sources of income, decreasing population growth rates, and increasing concern with environmental amenities. Some of the key research questions concern the conditions under which urbanization affects demand for resources implicated in global change, vulnerability to environmental disasters, and the robustness of rural communities in the face of environmental change. Equally relevant are concerns of population size. Increasing human population is likely to place added pressure on political and economic systems to contain conflicts likely to arise over increasingly scarce resources (see, e.g., Homer-Dixon, 1990).

Market Growth and Economic Development The spatial reach and dominance of market forces have been widening as a world system of trade penetrates even into countries that have had central planning and command economies and into the remotest regions. The effects on the human driving forces of global change and on the ability to respond are not obvious. Expansion of the market replaces state-sponsored resource waste with an invisible-hand means for checking inefficient and degrading uses of the environment. However, ceding control to the market can also lessen the ability of the state or community to manage environmental problems that are driven by the search for profits. At the local level, sustainable practices associated with a subsistence or mixed economy may be abandoned for unsustainable profit-oriented ones (Bates, 1980; Jodha and Mascarenhas, 1985; Redclift, 1987). The increased wealth that is the usual (though not always realized) goal of a shift toward free-market policies generally increases the ability to respond to threatening changes;

it may also raise the standard of environmental quality expected by the population.

Socioeconomic Marginalization Some observers hypothesize that the global spread of capitalism has forced certain individuals, groups, and countries into a position of diminishing control over needed resources and reduced options for survival and for responding to global change. Indigenous sociocultural systems of social security are believed to be crumbling, with new capitalist economies doing little to replace the lost safety nets. Economically marginalized individuals and groups sometimes degrade the environment for subsistence and lack the resources to respond effectively to natural or human-induced damage. Marginalization and impoverishment of nations can have the same consequences for national policies and actions (Hewitt, 1983; Sen, 1981; Watts, 1987).

Geopolitical Shifts The trend in 1989-1991 of declining tensions between East and West may facilitate human response to global environmental change through reallocating funds from military uses, lowering the potential for widespread nuclear and/ or chemical warfare, redefining national security to consider environmental as well as military and ideological threats (Brown, 1982; Mathews, 1989; Bush and Gorbachev, 1990), and building trust between powerful nations that will lead to cooperation instead of conflict. At the same time, however, north-south tensions may be increasing with the disparity of wealth between the developed and developing worlds. Such increased tension will make future international cooperative action more difficult and may lead to direct conflict (Agarwal, 1990; Carroll, 1983). The net effect of such geopolitical shifts is very hard to predict.

International Information/Communication Networks A global explosion of information and communication technology has uncertain implications for response to global change. It may facilitate societal response by making it easier for scientists and policy makers around the world to cooperate and share information, disseminate it to the public, and marshal worldwide pressure for response (Cleveland, 1990; Miles et al., 1988; Mowlana and Wilson, 1990; K. Wright, 1990). Examples include international reaction to satellite photographs of daily burning in the Amazon forests and the response of the Soviet peoples to news of the desiccation of the Aral Sea. However, the network may also amplify misinformation or create barriers to response by spreading the word that some nations may gain from environmental change.

Democratization As of mid-1991, there appears to be a worldwide trend toward increasing decision-making power of the

citizenry in nation-states. Increasing democratization may influence human response by providing more power to people being affected by environmental change, but it may also give more access and power to those whose interests would be harmed by measures for environmental management and protection. Democratization may also slow responses, compared with what might be achieved in an authoritarian regime by simple decision by the leadership (Kaplan, 1989; Muller, 1988; Roberts, 1990; Stephens, 1989). The net effects on response to global change are likely to depend on conditions in particular countries.

Scientific/Technological Expansion Exponential growth in scientific and technological knowledge both drives environmental change and increases the capacity to respond to it. It increases the ability to detect and understand threatening global environmental changes (e.g., the ozone hole) and provides alternatives to destructive products and practices (e.g., substitutes for CFCs) (AMBIO, 1989; Bacard, 1989; United Nations, 1989), but it may also create new global environmental problems (Kasprzyk, 1989; Russell, 1987). And new technologies may create major changes in the structure of human society, as in the case of CFC refrigeration technology or the periodic emergence of new energy sources to replace old ones as the basis of industry (Ausubel and Sladovich, 1989). In such instances, the implications for the global environment may remain uncertain for a long period.

Resurgence of Cultural Identity Many analysts perceive a worldwide resurgence of cultural identity or differentiation in recent decades: a deeply held attachment to groups (e.g., ethnic, religious, tribal, states) and the associated movements by these groups for autonomy of expression and decision (see Nash, 1989). Examples include the resurgence of ethnic nationalism in the Soviet Republics and the overt hostility, especially in Islamic countries, to the cultural invasion of Western values. The impact on response to global change is most likely to be felt when global changes or possible responses to them are perceived as threats to the values or livelihood of a particular group or when response requires cooperation between groups already in conflict.

The social changes mentioned appear to be ongoing trends, yet their future direction is, of course, uncertain. Equally uncertain are the effects of any trends in global human systems on the human ability to respond to global change. Plausible arguments can usually be made on both sides: a global social change may make resource use either more or less extensive and effective

human response either easier or harder to accomplish. The open questions point to many research opportunities for social scientists who have studied changes in these human systems and who would now consider their implications for human responses to global change.

CONCLUSIONS

This chapter examines the range of human consequences of global change and identifies specific areas in which new research can make important contributions to understanding. Where we identify research needs, priorities among studies should be set according to the criteria noted in Chapter 2 . We focus here on four general principles derived from this analysis that deserve special emphasis because they are fundamental, underappreciated, and point to critical directions for research.

T HE K NOWLEDGE B ASE FOR H UMAN R ESPONSES I S I NHERENTLY V ALUE L ADEN

We have identified the key link from environmental change to its human consequences as proximate effects on what humans value. Of course, what humans value depends on the humans. The wealthy tend to have different value priorities from the poor, national leaders from voters, business executives from laborers, miners from herders, and so forth. Yet what humans value is precisely what defines the consequences of global change and drives human responses. Different individuals and human groups will often disagree about what environmental changes are worthy of response.

Research Needs First, it is necessary to disaggregate the consequences of global change by analyzing the distribution of impacts of particular global changes on the things that different groups of people value. Such knowledge is necessary input to policy debates, even though it is not sufficient to facilitate social choices. Even with perfect knowledge of the effects of each conceivable alternative on each group affected, conflicts of value and interest will remain. Better knowledge of the impacts may even precipitate conflict by making latent conflicts more obvious.

Second, it is important to develop better ways of making the available knowledge about outcomes more accessible and understandable to nonspecialists. The body of knowledge about the de-

sign of messages about environmental risks and benefits can be brought to bear (National Research Council, 1989b; Mileti and Fitzpatrick, 1991). Better messages are also necessary but insufficient to facilitate social choices. They inform but do nothing to alter the differences in values and interests that produce conflict.

Third, it may help to understand the process of value judgment better. Several systematic methods have been used to assess the value people place on outcomes that may be affected by environmental change or responses to it, and to help individuals confront the value tradeoffs that policy choices often pose (e.g., Keeney and Raiffa, 1976; Mitchell and Carson, 1988). These methods of systematizing the valuation process can be applied to the valuation of the consequences of global change under different response regimes; such studies will advance understanding of valuation and may also help individuals and social groups choose their responses.

The most critical practical need is probably for effective means of managing the conflicts of value and interest that attend choices about global change. Human systems at every level of organization will have to develop systems of conflict management and, to the extent that different human groups (e.g., countries) need to respond in a coordinated way, their systems will also have to be compatible. These practical needs raise numerous research questions for the global change research agenda. In the discussion of conflict, we noted several bodies of relevant theory and knowledge that could be usefully applied to the study of conflict over responses to global environmental change. Methods of conflict management developed for other conflicts might be tried experimentally and monitored in efforts at global change-related conflict resolution. And experiments should be conducted with institutional means for making technological knowledge useful to nonexperts in a context of controversy—for instance, systems that enlist representatives of interested groups in the process (National Research Council, 1989b) or that harness the controversy to provide a range of perspectives as an aid to understanding (Stern, 1991).

H UMAN R ESPONSES M UST BE ASSESSED AGAINST A CHANGING BASELINE

The human consequences of an environmental change depend on when it happens and on the state of the affected human groups at that time. Global changes in the future may or may not have more serious effects than if they happened now. For instance, if recent trends continue, future societies will be wealthier, more

flexible, and more able to take global changes in stride than present ones. However, the more committed human societies become to present technologies that produce global change, the harder it will be to give them up if that becomes necessary.

Research Needs First, to understand the human consequences of global change, it is important to improve the ability to project social change. Existing methods range from simple extrapolation to more complex procedures for building scenarios. But scenario building is more art than science. Therefore, as an initial approach, it is useful to test projected environmental futures against various projected human futures to see how sensitive the human consequences of global change are to variations in the social future. In the longer run, it is much preferable to improve understanding of the relationships that drive social change. This is a long-term project in social science, on which much theoretical work is needed. We return to this theme in Chapter 5 . Research on the human dimensions of global change may help give impetus to that project.

Second, the extreme difficulty of predicting the long-term social future raises the importance of the study of social robustness in the face of environmental change. Increasing robustness against a range of environmental changes is a highly attractive strategy because it bypasses the difficult problems of predicting long-term environmental and social change. However, little is known about what makes social, economic, and technological systems robust, and the concept itself needs much more careful conceptualization.

The importance of the problem is suggested comparing two plausible arguments, both found in this chapter. One is that expansion of the market increases robustness by giving economic actors more flexibility in providing for their needs. This argument implies that further penetration of international markets will make it easier for humanity to withstand global changes without major suffering. The other argument is that sociocultural systems often provide a safety net for individuals, for example, through the obligations of others to provide. Sometimes, as in the responses to drought in northern Nigeria, these two arguments seem to support each other: the sociocultural systems there relied on the availability of urban wage labor as a supplement to subsistence agriculture. But sometimes, as with Amazonian deforestation, the two arguments seem to conflict: wealthy economic actors following market incentives crowd out peoples who have developed flexible sociocultural systems, leaving them neither land nor paid labor. Careful comparisons of cases such as the Sahel

and the Amazon might begin to clarify the role of markets and of various sociocultural systems in making social groups more or less robust with respect to environmental change.

H UMAN R ESPONSE C AN I NVOLVE I NTERVENTION A NYWHERE IN THE C YCLE OF C AUSATION

Human responses to global change can involve a variety of interventions of quite different types. It is reasonable to suppose that it makes a difference where an intervention occurs, but there is no body of knowledge that clarifies what different effects are likely to arise from different kinds of interventions. Consider an example in terms of Figure 4-1 . To respond to the threat of global warming, a government may regulate automobile manufacture or use (affecting a proximate cause—type P mitigation), institute a variety of fossil fuel taxes or incentives (to affect human systems that drive global change—type H mitigation), support research on solar energy (a more distantly type H mitigation), or support adjustment by investing in a fund to compensate citizens after the warming begins to affect what they value. Many arguments can be raised for each strategy. One may argue that mitigation directed at proximate causes is less likely to have disastrous side effects because it is targeted to the desired change only—or one may argue that adjustments are less likely to have disastrous side effects, for the same reason. One may argue that investing in solar energy is wiser than the other mitigation alternatives because it goes to the root of the carbon dioxide problem—or one may argue that it is less wise because too many things must go right for the investment to succeed. At present, not enough is known to shed light on such arguments in any systematic way.

We doubt that a general theory will be developed any time soon that can specify from the class of an intervention its likely effect and the types of unexpected consequences it might have. Such a theory will probably have to be inductive, and the necessary knowledge base does not exist. It is worthwhile to begin collecting the knowledge now.

Research Needs One research priority in the near-term should be to support studies that compare interventions at different points in the same causal cycle to identify their main and secondary effects. For example, the effects of regulating automobile fuel economy (a type P mitigation of global warming) can be compared with the effects of taxing gasoline (a type H mitigation); the ef-

fects of drought relief payments (an adjustment) can be compared with systems of crop insurance (an intervention to increase robustness). When the relevant interventions have been tried, the studies should be post hoc; when they have not been tried, theoretical analyses or studies based on responses to hypothetical situations will have to suffice.

Even absent a general theory of human intervention in environmental systems, the variety of opportunities to intervene implies an extensive agenda for ''normal'' social science research to assess the outcomes of interventions in response to anticipated or experienced environmental change. Research approaches developed for evaluating policy outcomes, studying the implementation process, comparing alternative approaches to regulation, and assessing the environmental and social impacts of government programs and policies can all be readily applied to the assessment of potential or actual responses to global change.

H UMAN R ESPONSES A FFECT THE D RIVING F ORCES OF G LOBAL C HANGE

Because the relationships of human systems and environmental systems are those of mutual causation, all human responses to global change potentially alter both systems. For many interventions, the secondary effects will be minuscule, but it is not always obvious which interventions will have the minuscule effects. Therefore, as a general rule, our conclusions about research on human causes apply equally to research on human responses. For example, policies in response to global change, which often attempt to change technology, social organization, economic structures, or even attitudes, contribute to the interactions of the human driving forces. Like the human causes, human responses can have short-term and long-term effects that may be quite different. And as with the study of the human causes, the study of human responses must be an interdisciplinary effort. Researchers will have to be attracted to the field from their home disciplines, and interdisciplinary research teams will have to be built. Human responses need to be studied separately at different levels of analysis and at different time scales; comparative studies in different social and temporal contexts are necessary; and research is needed to link responses at one level to those at other levels and short-term effects to long-term ones.

Global environmental change often seems to be the most carefully examined issue of our time. Yet understanding the human side—human causes of and responses to environmental change—has not yet received sustained attention. Global Environmental Change offers a strategy for combining the efforts of natural and social scientists to better understand how our actions influence global change and how global change influences us.

The volume is accessible to the nonscientist and provides a wide range of examples and case studies. It explores how the attitudes and actions of individuals, governments, and organizations intertwine to leave their mark on the health of the planet.

The book focuses on establishing a framework for this new field of study, identifying problems that must be overcome if we are to deepen our understanding of the human dimensions of global change, presenting conclusions and recommendations.

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