Science

Observed Impacts of Climate Change in the United States

Effects of Global Warming: Observed Impacts of Climate Change in the US

Observed Impacts of Global Climate Change in the U.S.

Prepared by the Pew Center on Global Climate Change
November 2004.

By:
Camille Parmesan, The University of Texas at Austin
Hector Galbraith, University of Colorado-Boulder and Galbraith Environmental Sciences


Press Release

Download Report (pdf)

Foreword

Eileen Claussen, President, Pew Center on Global Climate Change

For over a century, scientists have documented the important role that that the climate plays in the geographic distribution of the world’s ecosystems and the wildlife they support.  Yet, it is now quite evident that the climate these species depend upon is changing.  Global temperatures increased by over 1oF during the past century and are projected to increase 2.5-10.4oF by 2100 as a result of human emissions of greenhouse gases.  Given the reliance of plants and animals on their natural environment, they are often early barometers of the effects of climate change. 

“Observed Impacts of Global Climate Change in the U.S.” is the twelfth in a series of Pew Center reports examining the impacts of climate change on the U.S. environment.  While past Pew Center reports have reviewed the potential impacts of future climate change, this report provides compelling evidence that ecosystems are already responding to climate change and provides insights into what we can expect from future changes in the Earth’s climate.  Looking specifically at the United States, report authors, Drs. Camille Parmesan and Hector Galbraith find:

A number of ecological changes have already occurred in the United States over the past century in concert with increases in average U.S. temperature and changes in precipitation.  Warmer temperatures have resulted in longer growing seasons at the national level, altered carbon cycling and storage in the Alaskan tundra, and increased the frequency of fires and other disturbances in U.S. forests.  Individual species such as Edith’s checkerspot butterfly and the red fox have shifted north or to higher altitudes. Other species including Mexican jays and tree swallows have experienced changes in the timing of reproduction, as have plants such as forest phlox and butterfly weed.  While these changes illustrate efforts by species to adapt to a warming climate, these responses may alter competition and predator-prey relationships and have other unforeseen consequences. 
 
These observed changes have been linked to human-induced warming of the global climate.  There is increasingly strong evidence that the observed global climate change, particularly that of the past 50 years, is primarily the result of human emissions of greenhouse gases.  Changes in U.S. climate have also been linked with human activities. 

Changes in natural systems will continue and become even more apparent in the future, resulting in the degradation and loss of U.S. biodiversity. With continued and more severe changes in the climate, the ability of U.S. wildlife to adapt through migration and physiological change will be increasingly limited.  Furthermore, because of adaptive migration, species such as the red fox are now competing for habitat previously dominated by the arctic fox, threatening the arctic fox’s long-term survival.  The challenge is even greater when considered along with the broad range of other environmental threats currently affecting wildlife, such as habitat loss, environmental contamination, and invasive species. 

Efforts to reduce greenhouse gas emissions, protect U.S. ecosystems and wildlife, and provide refuge for sensitive species are all necessary to limit the future ecological consequences of climate change.  Curbing greenhouse gas emissions can reduce the rate and magnitude of future climate change, consequently reducing the severity of, but not preventing, climatic stresses to wildlife.  Meanwhile, the expansion of nature reserves and habitat conservation efforts can alleviate some non-climate stresses and enable species to better adapt to the effects of climate change. 

The authors and Pew Center gratefully acknowledge the input of Drs. Lou Pitelka and Walter Oechel on this report.  The Pew Center would also like to thank Joel Smith of Stratus Consulting for his assistance in the management of this Environmental Impacts Series.

Executive Summary

One of the major, most well-documented, and robust findings in ecology over the past century has been the crucial role of climate in determining the geographical distribution of species and ecological communities. Climate variability and change can affect plants and animals in a number of ways, including their distributions, population sizes, and even physical structure, metabolism, and behavior. These ecological responses to changes in climate have important implications, given the historical and continuing increases in atmospheric concentrations of greenhouse gases associated with human activities. Future human-induced changes in the global climate will directly affect regional conditions, such as geographic patterns of temperature and precipitation. Previous reports by the Pew Center on Global Climate Change have identified a range of future adverse effects that could occur in U.S. marine and freshwater systems, forests, and ecosystem processes due to greenhouse gas-induced global climate change.

The effect of climate change, however, is not relegated to future decades. Scientists have already documented changes in temperature and precipitation patterns in the United States and around the world. Average U.S. temperatures increased by approximately 0.6°C (1°F) over the past century. The magnitude of warming, however, has varied among different regions within the United States. Alaska, for example, has experienced average annual temperature increases of 2-4°C (4-7°F). Meanwhile, average U.S. precipitation has increased by 5-10 percent. These climatic changes have altered the environmental contexts within which many species live in the United States, causing physical, behavioral and location changes as the species respond to their changing environments. In addition to being biological indicators of global warming, these changes may have direct adverse effects on U.S. biodiversity and ecosystem stability, resilience, and goods and services.

This report assesses the scientific evidence compiled to date on the observed ecological effects of climate change in the United States and their consequences. It evaluates the strength of that evidence and the relationships between observed biological changes and human activities. Although many species and ecological systems of interest have yet to be studied (often due to inherent limitations of available data) and the attribution of ecological changes to a particular cause remains challenging, a number of robust findings emerge from this report.

1) Sufficient studies now exist to conclude that the consequences of climate change are already detectable within U.S. ecosystems. This report reviews more than 40 studies that associate climate change with observed ecological impacts in the United States, and, using objective evaluation criteria, finds that more than half provide strong evidence of a direct link. These studies span a broad range of plant and animal species from various regions of the United States. Yet, despite the diversity among studies, the observed ecological responses are consistent with one another, as well as with the changes that one would expect based on the nature of U.S. climate change observed to date. 

2) The timing of important ecological events, including the flowering of plants and the breeding times of animals, has shifted, and these changes have occurred in conjunction with changes in U.S. climate. If these timing shifts are synchronous across species that normally interact with each other (for example, if adult butterflies and the flowers they depend on for nectar both emerge two weeks earlier), then these species’ interactions are preserved, and the system may remain healthy. On the other hand, if responses to temperature increases vary across species (for example, if butterflies emerge before the flowers they depend on for survival), then species’ interactions may become out of synchrony and could lead to population declines. Both types of situations have been documented.

3) Geographic ranges of some plants and animals have shifted northward and upward in elevation, and in some cases, contracted. One of the most detailed and best-studied examples is the Edith’s checkerspot butterfly in the western United States. As temperatures have increased over the last century, many southern and lower-elevation populations of this species have disappeared entirely. The effect of this shift has been a contraction of the species’ range to the north (i.e., it is disappearing from Mexico but thriving in Canada).  The red fox, another example, has shifted northward and is now encroaching on the arctic fox’s range, threatening its survival. Similar range shifts within the United States have also been observed in organisms as diverse as birds, mammals, intertidal invertebrates, and plants. Such major shifts alter species’ interactions and potentially threaten U.S. biodiversity.

4) Species composition within communities has changed in concert with local temperature rise. As species within a community change abundances or, ultimately, are added or lost, the relationships among species also change. In particular, such shifts in composition are likely to alter important competitive and predatory/prey relationships, which can reduce local or regional biodiversity. A particularly compelling example of this is the change observed over more than 60 years in the intertidal communities of Monterey, California, where a community previously dominated by northern colder-water species has been “infiltrated” by southern warmer-water species in response to oceanic warming. Similar changes have also been observed in nearby offshore marine fish communities. Thus, many protected lands, such as the marine reserve in Monterey Bay, are experiencing a shift in the communities that they protect.

5) Ecosystem processes such as carbon cycling and storage have been altered by climate change. The lengthening of the growing season has altered the annual cycle of carbon-dioxide (CO2) levels in the atmosphere, because plants are a major intermediary for carbon flow through ecosystems. The Alaskan tundra has switched from being a net sink of CO2 (absorbing and storing more carbon from the atmosphere than is released) to being a net source of CO2 (releasing more carbon than is stored), because warmer winters have allowed previously stored dead plant matter in the soil to decompose and release CO2. Like the tundra, boreal forests have become carbon sources because of reduced growth due to climate-mediated increases in water stress, pest outbreaks, and wildfires. Conversely, many of the forests of the lower 48 states have switched in the opposite direction—becoming carbon sinks in recent decades. This transition is attributed to regrowth of forests following logging and abandonment of agricultural fields.  However, it is expected to stop as soon as the forests mature.

6) The findings that climate change is affecting U.S. biological systems are consistent across different geographic scales and a variety of species, and these U.S. impacts reflect global trends. Even against a background of apparently dominating forces such as direct human-driven habitat destruction and alteration, a climate “fingerprint” is discernible in natural systems. The most rigorous studies within the United States provide strong evidence that climate change has affected the timing of biological events in at least three taxa (i.e., groups of related species). They also provide strong evidence that at least three taxa have shifted their ranges in response to climate change and that climate change has altered ecological communities and processes. Further, very few instances of biotic change run completely counter to climate-change predictions, and the findings of many of the U.S. studies are mirrored by studies elsewhere around the world. Climate change has the potential to degrade ecosystem functions vital to global health. If the observed biological changes are merely one phase in a cyclical pattern of warming and cooling periods, then they may not represent a threat to long-term species and ecosystem health. If, however, they are linked to anthropogenic climate change, they will continue along the same path. Thus, it is essential to address the extent to which the U.S. climate change responsible for observed ecological responses can be attributed to global emissions of anthropogenic greenhouse gases.

7) There is an emerging link between observed changes in wild plants and animals across the United States and human-driven global increases in greenhouse gases.   In 2001, the Intergovernmental Panel on Climate Change concluded that the global rise in average yearly temperature over the past 50 years was primarily due to increased concentrations of anthropogenic greenhouse gases. U.S. climate trends are consistent with global climate trends. Global biological trends are predicted by (and match) observed climate trends, indicating that anthropogenic global climate change has affected natural systems. Recent research focusing on North America has also shown a significant greenhouse gas signal in North American climate trends over the past 50 years. The combination of strong consistency across climate and biological studies and across scales (from regional to global), coupled with new climate analyses specific to the United States, links U.S. biological changes to anthropogenic climate change. The implications of this link are that current biological trends will continue over future decades as greenhouse gas emissions continue to rise.

8) The addition of climate change to the mix of stressors already affecting valued habitats and endangered species will present a major challenge to future conservation of U.S. ecological resources. Many if not most of the ecosystems and organisms in the United States are already suffering from other anthropogenic stressors such as habitat destruction or fragmentation, introduction of invasive species, and contamination. As yet, scientists do not have a clear idea how climate change might affect this already fragile situation. It is likely, however, that in many cases climate change may exacerbate current conditions, further stressing wild species and their associated ecosystems. There is a growing consensus within the scientific community that climate change will compound existing threats and lead to an acceleration of the rate at which biodiversity is lost.

9) In the future, range contractions are more likely than simple northward or upslope shifts.  During historic glacial cycles, range shifts of hundreds to thousands of miles were common, and species extinction was rare. However, achieving such massive relocation is much more problematic across the human-dominated, artificially fragmented landscapes of today. The large reduction in the areas of natural habitats and the growth of barriers to species’ dispersal (urban and agricultural zones) makes simple range shifts unlikely. Species that are not adapted to urban and agricultural environments are likely to be confined to smaller total geographic areas as climate causes them to contract from their southern and lower boundaries.  Already rare or endangered species, or those living only on high mountaintops, are likely to have the highest risk of extinction.

10) Reducing the adverse effects of climate change on U.S. ecosystems can be facilitated through a broad range of strategies, including adaptive management, promotion of transitional habitat in nonpreserved areas, and the alleviation of nonclimate stressors. The protection of transitional habitat that links natural areas might assist in enabling species migration in response to climate change. Meanwhile, promoting dynamic design and management plans for nature reserves may enable managers to facilitate the adjustment of wild species to changing climate conditions (e.g., through active relocation programs). Also, because climate change may be particularly dangerous to natural systems when superimposed on already existing stressors, alleviation of the stress due to these other anthropogenic factors may help reduce their combined effects with climate change.

Conclusions

1) Sufficient studies now exist to conclude that the consequences of climate change are already detectable within U.S. ecosystems. This report reviews more than 40 studies that associate climate change with observed ecological impacts in the United States, and, using objective evaluation criteria, finds that more than half provide strong evidence of a direct link. These studies span a broad range of plant and animal species from various regions of the United States. Yet, despite the diversity among studies, the observed ecological responses are consistent with one another, as well as with the changes that one would expect based on the nature of U.S. climate change observed to date. 

2) The timing of important ecological events, including the flowering of plants and the breeding times of animals, has shifted, and these changes have occurred in conjunction with changes in U.S. climate. If these timing shifts are synchronous across species that normally interact with each other (for example, if adult butterflies and the flowers they depend on for nectar both emerge two weeks earlier), then these species’ interactions are preserved, and the system may remain healthy. On the other hand, if responses to temperature increases vary across species (for example, if butterflies emerge before the flowers they depend on for survival), then species’ interactions may become out of synchrony and could lead to population declines. Both types of situations have been documented.

3) Geographic ranges of some plants and animals have shifted northward and upward in elevation, and in some cases, contracted. One of the most detailed and best-studied examples is the Edith’s checkerspot butterfly in the western United States. As temperatures have increased over the last century, many southern and lower-elevation populations of this species have disappeared entirely. The effect of this shift has been a contraction of the species’ range to the north (i.e., it is disappearing from Mexico but thriving in Canada).  The red fox, another example, has shifted northward and is now encroaching on the arctic fox’s range, threatening its survival. Similar range shifts within the United States have also been observed in organisms as diverse as birds, mammals, intertidal invertebrates, and plants. Such major shifts alter species’ interactions and potentially threaten U.S. biodiversity.

4) Species composition within communities has changed in concert with local temperature rise. As species within a community change abundances or, ultimately, are added or lost, the relationships among species also change. In particular, such shifts in composition are likely to alter important competitive and predatory/prey relationships, which can reduce local or regional biodiversity. A particularly compelling example of this is the change observed over more than 60 years in the intertidal communities of Monterey, California, where a community previously dominated by northern colder-water species has been “infiltrated” by southern warmer-water species in response to oceanic warming. Similar changes have also been observed in nearby offshore marine fish communities. Thus, many protected lands, such as the marine reserve in Monterey Bay, are experiencing a shift in the communities that they protect.

5) Ecosystem processes such as carbon cycling and storage have been altered by climate change. The lengthening of the growing season has altered the annual cycle of carbon-dioxide (CO2) levels in the atmosphere, because plants are a major intermediary for carbon flow through ecosystems. The Alaskan tundra has switched from being a net sink of CO2 (absorbing and storing more carbon from the atmosphere than is released) to being a net source of CO2 (releasing more carbon than is stored), because warmer winters have allowed previously stored dead plant matter in the soil to decompose and release CO2. Like the tundra, boreal forests have become carbon sources because of reduced growth due to climate-mediated increases in water stress, pest outbreaks, and wildfires. Conversely, many of the forests of the lower 48 states have switched in the opposite direction—becoming carbon sinks in recent decades. This transition is attributed to regrowth of forests following logging and abandonment of agricultural fields.  However, it is expected to stop as soon as the forests mature.

6) The findings that climate change is affecting U.S. biological systems are consistent across different geographic scales and a variety of species, and these U.S. impacts reflect global trends. Even against a background of apparently dominating forces such as direct human-driven habitat destruction and alteration, a climate “fingerprint” is discernible in natural systems. The most rigorous studies within the United States provide strong evidence that climate change has affected the timing of biological events in at least three taxa (i.e., groups of related species). They also provide strong evidence that at least three taxa have shifted their ranges in response to climate change and that climate change has altered ecological communities and processes. Further, very few instances of biotic change run completely counter to climate-change predictions, and the findings of many of the U.S. studies are mirrored by studies elsewhere around the world. Climate change has the potential to degrade ecosystem functions vital to global health. If the observed biological changes are merely one phase in a cyclical pattern of warming and cooling periods, then they may not represent a threat to long-term species and ecosystem health. If, however, they are linked to anthropogenic climate change, they will continue along the same path. Thus, it is essential to address the extent to which the U.S. climate change responsible for observed ecological responses can be attributed to global emissions of anthropogenic greenhouse gases.

7) There is an emerging link between observed changes in wild plants and animals across the United States and human-driven global increases in greenhouse gases.   In 2001, the Intergovernmental Panel on Climate Change concluded that the global rise in average yearly temperature over the past 50 years was primarily due to increased concentrations of anthropogenic greenhouse gases. U.S. climate trends are consistent with global climate trends. Global biological trends are predicted by (and match) observed climate trends, indicating that anthropogenic global climate change has affected natural systems. Recent research focusing on North America has also shown a significant greenhouse gas signal in North American climate trends over the past 50 years. The combination of strong consistency across climate and biological studies and across scales (from regional to global), coupled with new climate analyses specific to the United States, links U.S. biological changes to anthropogenic climate change. The implications of this link are that current biological trends will continue over future decades as greenhouse gas emissions continue to rise.

8) The addition of climate change to the mix of stressors already affecting valued habitats and endangered species will present a major challenge to future conservation of U.S. ecological resources. Many if not most of the ecosystems and organisms in the United States are already suffering from other anthropogenic stressors such as habitat destruction or fragmentation, introduction of invasive species, and contamination. As yet, scientists do not have a clear idea how climate change might affect this already fragile situation. It is likely, however, that in many cases climate change may exacerbate current conditions, further stressing wild species and their associated ecosystems. There is a growing consensus within the scientific community that climate change will compound existing threats and lead to an acceleration of the rate at which biodiversity is lost.

9) In the future, range contractions are more likely than simple northward or upslope shifts.  During historic glacial cycles, range shifts of hundreds to thousands of miles were common, and species extinction was rare. However, achieving such massive relocation is much more problematic across the human-dominated, artificially fragmented landscapes of today. The large reduction in the areas of natural habitats and the growth of barriers to species’ dispersal (urban and agricultural zones) makes simple range shifts unlikely. Species that are not adapted to urban and agricultural environments are likely to be confined to smaller total geographic areas as climate causes them to contract from their southern and lower boundaries.  Already rare or endangered species, or those living only on high mountaintops, are likely to have the highest risk of extinction.

10) Reducing the adverse effects of climate change on U.S. ecosystems can be facilitated through a broad range of strategies, including adaptive management, promotion of transitional habitat in nonpreserved areas, and the alleviation of nonclimate stressors. The protection of transitional habitat that links natural areas might assist in enabling species migration in response to climate change. Meanwhile, promoting dynamic design and management plans for nature reserves may enable managers to facilitate the adjustment of wild species to changing climate conditions (e.g., through active relocation programs). Also, because climate change may be particularly dangerous to natural systems when superimposed on already existing stressors, alleviation of the stress due to these other anthropogenic factors may help reduce their combined effects with climate change.

Camilla Parmesan
Hector Galbraith
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Climate Data: Insights and Observations

Climate Data Report Cover

Climate Data: Insights and Observations

Prepared for the Pew Center on Global Climate Change
November 2004

By:
Kevin Baumert, Jonathan Pershing, with contributions from Timothy Herzog, Matthew Markoff, World Resources Institute

Press Release

Download entire report (pdf)

Descargar el reportaje en español (pdf)

Jonathan Pershing
Kevin Baumert
Matthew Markoff
Timothy Herzog
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An Effective Approach to Climate Change

POLICY FORUM: CLIMATE POLICY

An Effective Approach to Climate Change

By Eileen Claussen

Enhanced online at www.sciencemag.org/cgi/content/full/306/5697/816
Originally published October 29, 2004: VOL 306 SCIENCE

The Bush Administration’s “business as usual” climate change policy (1), with limited R&D investments, no mandates for action, and no plan for adapting to climate change, is inadequate. We must start now to reduce emissions and to spur the investments necessary to reduce future emissions. We also need a proactive approach to adaptation to limit the severity and costs of climate change impacts.

Science and Economics

Those who are opposed to national climate change policies make much of the uncertainties in climate models, specifically the rate and magnitude of global warming. The Climate Change Science Program’s plan, points out Secretary Abraham, would address these uncertainties, although he offers no assurances that the program will be adequately funded. However, the scientific community already agrees on three key points: global warming is occurring; the primary cause is fossil fuel consumption; and if we don’t act now to reduce greenhouse gas (GHG) emissions, it will get worse.

Yes, there are uncertainties in future trends of GHG emissions. However, even if we were able to stop emitting GHGs today, warming will continue due to the GHGs already in the atmosphere (2).

National climate change policy has not changed significantly for several years. The first President Bush pursued a strategy of scientific research and voluntary GHG emissions reductions. The new Climate Change Science Program has a budget comparable, in inflation-adjusted dollars, to its predecessor, the Global Climate Research Program, during the mid-1990s. The Administration’s current GHG intensity target will increase absolute emissions roughly 14% above 2000 levels and 30% above 1990 levels by 2010 (3). These increases will make future mitigation efforts much more difficult and costly.

While reducing uncertainty is important, we must also focus on achieving substantial emissions reductions and adapting to climate change.

Low-Carbon Technology Development

The Administration’s more substantive R&D initiatives, such as Hydrogen Fuels and FutureGen (clean coal) are relatively modest investments in technologies that are decades away from deployment. We need a far more vigorous effort to promote energy efficient technologies; to prepare for the hydrogen economy; to develop affordable carbon capture and sequestration technologies; and to spur the growth of renewable energy, biofuels, and coal-bed methane capture.

Equally important, we need to encourage public and private investment in a wide-ranging portfolio of low-carbon technologies. Despite the availability of such technologies for energy, transportation, and manufacturing, there is little motivation for industry to use them. Widespread use of new technology is most likely when there are clear and consistent policy signals from the government (4).

One-fifth of U.S. emissions comes from cars and trucks (5). The Administration’s targets to improve fuel economy for light trucks and “sports utility” vehicles (SUVs) by 1.5 miles per gallon over the next three model years fall far short of what is already possible. California is setting much more ambitious emission standards for cars and light trucks. Current efficiency standards can be improved by 12% for subcompacts to 27% for larger cars without compromising performance (5).Hybrid vehicles can already achieve twice the fuel efficiency of the average car.

About one-third of U.S. emissions results from generating energy for buildings (6). Policies that increase energy efficiency using building codes, appliance efficiency standards, tax incentives, product efficiency labeling, and Energy Star programs, can significantly reduce emissions and operating costs. Policies that promote renewable energy can reduce emissions and spur innovation.Sixteen states have renewable energy mandates (7).

The Power of the Marketplace

Policies that are market driven can help achieve environmental targets cost-effectively. A sustained price signal, through a cap-and-trade program, was identified as the most effective policy driver by a group of leaders from state and local governments, industry, and nongovernmental organizations (NGOs) (8).

Senators Lieberman (D–CT) and McCain’s (R–AZ) 2003 Climate Stewardship Act proposes a market-based approach to cap GHG emissions at 2000 levels by 2010. The bill, opposed by the Administration, garnered the support of 44 Senators. Nine Northeastern states are developing a regional “cap-and-trade” initiative to reduce power plant emissions. An important first step would be mandatory GHG emissions reporting.

Adapting to Climate Change

An important issue that Secretary Abraham failed to address is the need for anticipating and adapting to the climate change we are already facing. Economic sectors with long-lived investments, such as water resources, coastal resources, and energy may have difficulty adapting (9). A proactive approach to adaptation could limit the severity and costs of the impacts of climate change.

By limiting emissions and promoting technological change, the United States could put itself on a path to a low-carbon future by 2050, cost-effectively. Achieving this will require a much more explicit and comprehensive national commitment than we have seen to date. The rest of the developed world, including Japan and the European Union, is already setting emission-reduction targets and enacting carbon-trading schemes. Far from “leading the way” on climate change at home and around the world, as Secretary Abraham suggested, the United States has fallen behind.

References and Notes

1. S. Abraham, Science 305, 616 (2004). |
2. R. T. Wetherald, R. J. Stouffer, K. W. Dixon, Geophys. Res. Lett. 28, 1535 (2001).
3. “Analysis of President Bush’s climate change plan” (Pew Center on Global Climate Change,Arlington,VA, February 2002); available at www.c2es.org.
4. J. Alic, D. Mowery, E. Rubin, “U.S. technology and innovation policies: Lessons for climate change” (Pew Center on Global Climate Change,Arlington,VA, 2003).
5. National Research Council, “The effectiveness and impact of corporate average fuel economy (CAFÉ) standards” (National Academies Press, Washington, DC, 2002).
6. “U.S. greenhouse gas emissions and sinks: 1990–2002”(EPA/430-R-04-003, Environmental Protection Agency, Washington, DC, 2002), Table 3–6.2002.
7. Workshop proceedings, “The 10-50 solution: Technologies and policies for a low-carbon future,”Washington, DC, 25 and 26 March 2004 (The Pew Center on Global Climate Change and the National Commission on Energy Policy, Arlington,VA, in press).
8. J. Smith, “A synthesis of potential climate change impacts on the United States” (Pew Center on Global Climate Change, Arlington,VA, 2004). Published by AAAS

by Eileen Claussen, President— Appeared in Science, October 29, 2004
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The Role of Adaptation in the U.S.

Climate Change Adaptation Cover  

Coping with Global Climate Change: The Role of Adaptation in the United States

Prepared for the Pew Center on Global Climate Change
June 2004

By:
William Easterling of Pennsylvania State University
Brian Hurd of New Mexico State University
Joel Smith of Stratus Consulting Inc.


Press Release

Download Report (pdf)

Foreword

 

Eileen Claussen, President, Pew Center on Global Climate Change

Throughout the next century and beyond, global climate change will have significant effects on both important economic sectors and natural resources across the United States.   Global temperatures are projected to increase 2.5-10.4oF by 2100, and at least some of this warming is now unavoidable.   Although the natural streams, wetlands, and biodiversity of the United States have a limited capacity to adapt to a changing climate, those systems that are managed by humans, such as agriculture, water resources, and coastal development can be handled in ways to reduce the severity of adverse impacts. 

Adaptation and Global Climate Change discusses how the United States might cope with anticipated climate change impacts in the coming decades.   This report provides a review of the role of adaptation in addressing climate change, the options available for increasing our ability to adapt, and the extent to which adaptation can reduce the consequences of climate change to the U.S. economy and natural resources.  Report authors Bill Easterling, Brian Hurd, and Joel Smith find:

  • Adaptation is an important complement to greenhouse gas mitigation policies. Reducing greenhouse gas emissions is the only effective mechanism for preventing adverse impacts of climate change.  However, given that additional future climate change is now inevitable regardless of mitigation efforts, adaptation is an essential strategy for reducing the severity and cost of climate change impacts.
     
  • Adapting to climate change will not be a smooth or cost-free endeavor.  Although the United States has diverse options and resources for adapting to the adverse effects of climate change, changes will be made in an atmosphere of uncertainty.  Substantial investments and adjustments will need to be made even with imperfect information or foresight, and successful adaptation will become even more challenging with more rapid rates or greater degrees of warming.
     
  • Managed systems will fare better than natural systems and some regions will face greater obstacles than others. Even if there are some successes in adapting to climate change at the national level, there will still be regional and sectoral losers.  In particular, there is limited ability for humans to improve the adaptive capacity of natural ecosystems, which are not as easily managed and which face degradation from multiple stresses.
     
  • Proactive approaches to adaptation are more likely to avoid or reduce damages than reactive responses.   Anticipatory planning among government institutions and important economic sectors will enhance the resilience to the effects of climate change.  Government at all levels should consider the implications of climate change when making investments in long-lived infrastructure.

The authors and the Pew Center gratefully acknowledge the input of Drs. Gary Yohe and Paul Kirshen on this report.

Executive Summary

 

Climate change resulting from increased greenhouse gas concentrations has the potential to harm societies and ecosystems. In particular, agriculture, forestry, water resources, human health, coastal settlements, and natural ecosystems will need to adapt to a changing climate or face diminished functions. Reductions in emissions of greenhouse gases and their concentration in the atmosphere will tend to reduce the degree and likelihood that significantly adverse conditions will result. Consideration of actions—e.g., mitigation policy—that can reduce this likelihood is reasonable and prudent, and has generally been the primary focus of public attention and policy efforts on climate change. However, recognition is increasing that the combination of continued increases in emissions and the inertia of the climate system means that some degree of climate change is inevitable. Even if extreme measures could be instantly taken to curtail global emissions, the momentum of the earth’s climate is such that warming cannot be completely avoided. Although essential for limiting the extent, and indeed the probability, of rapid and severe climate change, mitigation is not, and this paper argues, should not be, the only protective action in society’s arsenal of responses.

Adaptation actions and strategies present a complementary approach to mitigation. While mitigation can be viewed as reducing the likelihood of adverse conditions, adaptation can be viewed as reducing the severity of many impacts if adverse conditions prevail. That is, adaptation reduces the level of damages that might have otherwise occurred. However, adaptation is a risk-management strategy that is not free of cost nor foolproof, and the worthiness of any specific actions must therefore carefully weigh the expected value of the avoided damages against the real costs of implementing the adaptation strategy.

Adaptation to environmental change is a fundamental human trait and is not a new concept. Throughout the ages, human societies have shown a strong capacity for adapting to different climates and environmental changes, although not always successfully. As evidenced by the widespread and climatically diverse location of human settlements throughout the world, humans have learned how to thrive in a wide variety of climate regimes, ranging from cold to hot and from humid to dry. The resilience and flexibility exhibited in the patterns of human settlements evidence an inherent desire and some measure of capacity to adapt.

For human systems, the success of adaptation depends critically on the availability of necessary resources, not only financial and natural resources, but also knowledge, technical capability, and institutional resources. The types and levels of required resources, in turn, depend fundamentally on the nature and abruptness of the actual or anticipated environmental change and the range of considered responses.

The processes of adaptation to climate change in both human and natural systems are highly complex and dynamic, often entailing many feedbacks and dependencies on existing local and temporal conditions. The uncertainties introduced by the complexity, scale and limited experience with respect to anthropogenic climate change explains the limited level of applied research conducted thus far on adaptation, the reliance on mechanistic assumptions, and widespread use of scenarios and historical analogues. In addition, many social, economic, technological and environmental trends will critically shape the future ability of societal systems to adapt to climate change. While such factors as increased population and wealth will likely increase the potential level of material assets that are exposed to the risks of climate change, greater wealth and improved technology also extend the resources and perhaps the capabilities to adapt to climate change. These trends must be taken into account when evaluating the nature and scale of future adaptive responses and the likelihood that they will succeed.

The implications of climate change are more dire for natural systems, because it will be difficult for many species to change behavior or migrate in response to climate change. While biological systems might accommodate minor (or slowly occurring) perturbations in a smooth continuous fashion, even minor changes in climate may be disruptive for many ecosystems and individual species. In addition, many of the world’s species are currently stressed by a variety of factors including urban development, pollution, invasive species, and fractured (or isolated) habitats. Such conditions, coupled with the relatively rapid rate of anticipated climate change, are likely to challenge many species’ resiliency and chances for successful adaptation.

Key insights and findings on adaptation and its potential for success are summarized below:

  1. Adaptation and mitigation are necessary and complementary for a comprehensive and coordinated strategy that addresses the problem of global climate change. By lessening the severity of possible damages, adaptation is a key defensive measure. Adaptation is particularly important given the mounting evidence that some degree of climate change is inevitable. Recognizing a role for adaptation does not, however, diminish or detract from the importance of mitigation in reducing the rate and likelihood of significant climate change.
     
  2. The literature indicates that U.S. society can on the whole adapt with either net gains or some costs if warming occurs at the lower end of the projected range of magnitude, assuming no change in climate variability and generally making optimistic assumptions about adaptation. However, with a much larger magnitude of warming, even making relatively optimistic assumptions about adaptation, many sectors would experience net losses and higher costs. The thresholds in terms of magnitudes or rates of change (including possible non-linear responses) in climate that will pose difficulty for adaptation are uncertain. In addition, it is uncertain how much of an increase in frequency, intensity, or persistence of extreme weather events the United States can tolerate.
     
  3. To say that society as a whole “can adapt“ does not mean that regions and peoples will not suffer losses. For example, while the agricultural sector as a whole may successfully adapt, some regions may gain and others may lose. Agriculture in many northern regions is expected to adapt to climate change by taking advantage of changing climatic conditions to expand production, but agriculture in many southern regions is expected to contract with warmer, drier temperatures. Individual farmers not benefiting from adaptation may lose their livelihood.  In addition, other individuals or populations in these and other regions can be at risk, because they could be adversely affected by climate change and lack the capacity to adapt.  This is particularly true of relatively low-income individuals and groups whose livelihoods are depending on resources at risk by climate change.
     
  4. Adaptation is not likely to be a smooth process or free of costs. While studies and history show that society can on the whole adapt to a moderate amount of warming, it is reasonable to expect that mistakes will be made and costs will be incurred along the way. People are neither so foolish as to continue doing what they have always done in the face of climate change, nor so omniscient as to perfectly understand what will need to be done and to carry it out most efficiently. In reality, we are more likely to muddle through, taking adaptive actions as necessary, but often not doing what may be needed for optimal or ideal adaptation. Additionally, adaptation is an on-going process rather than a one-shot instantaneous occurrence.  Compounding society’s shortcomings, a more rapid, variable, or generally unpredictable climate change would add further challenges to adaptation.
     
  5. Effects on ecosystems, and on species diversity in particular, are expected to be negative at all but perhaps the lowest magnitudes of climate change because of the limited ability of natural systems to adapt. Although biological systems have an inherent capacity to adapt to changes in environmental conditions, given the rapid rate of projected climate change, adaptive capacity is likely to be exceeded for many species. Furthermore, the ability of ecosystems to adapt to climate change is severely limited by the effects of urbanization, barriers to migration paths, and fragmentation of ecosystems, all of which have already critically stressed ecosystems independent of climate change itself.
     
  6. Institutional design and structure can heighten or diminish society’s exposure to climate risks. Long-standing institutions, such as disaster relief payments and insurance programs, affect adaptive capacity. Coastal zoning, land-use planning, and building codes are all examples of institutions that can contribute to (or detract from) the capacity to withstand climate changes in efficient and effective ways.
     
  7. Proactive adaptation can reduce U.S. vulnerability to climate change. Proactive adaptation can improve capacities to cope with climate change by taking climate change into account in long-term decision-making, removing disincentives for changing behavior in response to climate change (such as removing subsidies for maladaptive activities), and introducing incentives to modify behavior in response to climate change (such as the use of market-based mechanisms to promote adaptive responses). Furthermore, improving and strengthening human capital through education, outreach, and extension services improves decision-making capacity at every level and increases the collective capacity to adapt.

Conclusions

 

As the climate-change research and policy communities fully confront the challenges of understanding and managing adaptation to climate change, the issues framed in this report provide important insight concerning the information needed to make appropriate policy choices regarding adaptation. The following conclusions provide initial guidance to those communities:

  1. Adaptation and mitigation are necessary and complementary for a comprehensive and coordinated strategy that addresses the problem of global climate change. By lessening the severity of possible damages, adaptation is a key defensive measure. Adaptation is particularly important given the mounting evidence that some degree of climate change is inevitable. Recognizing a role for adaptation does not, however, diminish or detract from the importance of mitigation in reducing the rate and likelihood of significant climate change.
     
  2. The literature indicates that U.S. society can on the whole adapt with either net gains or some costs if warming occurs at the lower end of the projected range of magnitude, assuming no change in climate variability and generally making optimistic assumptions about adaptation. However, with a much larger magnitude of warming, even making relatively optimistic assumptions about adaptation, many sectors would experience net losses and higher costs. The thresholds in terms of magnitudes or rates of change (including possible non-linear responses) in climate that will pose difficulty for adaptation are uncertain. In addition, it is uncertain how much of an increase in frequency, intensity, or persistence of extreme weather events the United States can tolerate.
     
  3. To say that society as a whole “can adapt“ does not mean that regions and peoples will not suffer losses. For example, while the agricultural sector as a whole may successfully adapt, some regions may gain and others may lose. Agriculture in many northern regions is expected to adapt to climate change by taking advantage of changing climatic conditions to expand production, but agriculture in many southern regions is expected to contract with warmer, drier temperatures. Individual farmers not benefiting from adaptation may lose their livelihood. In addition, other individuals or populations in these and other regions can be at risk, because they could be adversely affected by climate change and lack the capacity to adapt.  This is particularly true of relatively low-income individuals and groups whose livelihoods are depending on resources at risk by climate change.
     
  4. Adaptation is not likely to be a smooth process or free of costs. While studies and history show that society can on the whole adapt to a moderate amount of warming, it is reasonable to expect that mistakes will be made and costs will be incurred along the way. People are neither so foolish as to continue doing what they have always done in the face of climate change, nor so omniscient as to perfectly understand what will need to be done and to carry it out most efficiently. In reality, we are more likely to muddle through, taking adaptive actions as necessary, but often not doing what may be needed for optimal or ideal adaptation. Additionally, adaptation is an on-going process rather than a one-shot instantaneous occurrence.  Compounding society’s shortcomings, a more rapid, variable, or generally unpredictable climate change would add further challenges to adaptation.
     
  5. Effects on ecosystems, and on species diversity in particular, are expected to be negative at all but perhaps the lowest magnitudes of climate change because of the limited ability of natural systems to adapt. Although biological systems have an inherent capacity to adapt to changes in environmental conditions, given the rapid rate of projected climate change, adaptive capacity is likely to be exceeded for many species. Furthermore, the ability of ecosystems to adapt to climate change is severely limited by the effects of urbanization, barriers to migration paths, and fragmentation of ecosystems, all of which have already critically stressed ecosystems independent of climate change itself.
     
  6. Institutional design and structure can heighten or diminish society’s exposure to climate risks. Long-standing institutions, such as disaster relief payments and insurance programs, affect adaptive capacity. Coastal zoning, land-use planning, and building codes are all examples of institutions that can contribute to (or detract from) the capacity to withstand climate changes in efficient and effective ways. 
     
  7. Proactive adaptation can reduce U.S. vulnerability to climate change. Proactive adaptation can improve capacities to cope with climate change by taking climate change into account in long-term decision-making, removing disincentives for changing behavior in response to climate change (such as removing subsidies for maladaptive activities), and introducing incentives to modify behavior in response to climate change (such as the use of market-based mechanisms to promote adaptive responses). Furthermore, improving and strengthening human capital through education, outreach, and extension services improves decision-making capacity at every level and increases the collective capacity to adapt.

About the Authors

 

Dr. William E. Easterling
Dr. William E. Easterling is the Director of the Institutes of Environment and a professor of geography and agronomy at Pennsylvania State University.   Prior to joining the faculty at Penn State, Dr. Easterling held appointments in the Department of Agricultural Meteorology at the University of Nebraska (1991-1997), Resources for the Future, Inc. in Washington, DC (1987-1991), and the Illinois State Water Survey at the University of Illinois (1984-1987).  He received his doctorate in geography from the University of North Carolina at Chapel Hill.  Dr. Easterling's research concerns the interactions of human activities with their climatic and biotic environment, particularly the potential effects of climate changes from greenhouse warming on agroecosystem productivity and adaptation in both developed and developing countries. He also serves or has served on numerous national and international scientific advisory committees and assessment projects, including those of the National Research Council, the National Science Foundation, the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, and the U. S. Department of Energy. He served as the Acting Director of the Department of Energy's National Institute for Global Environmental Change (1996-1998), and he was a convening lead author for the Third Assessment Report of the United Nations/World Meteorological Organization's Intergovernmental Panel on Climate Change. In the winter of 2003, he co-chaired newly elected Pennsylvania Governor Ed Rendell's Transition Committee on Conservation and Natural Resources and was elected to serve as the Chair of the Penn State University Research Council for 2003-2004.

Brian H. Hurd, New Mexico State University
Brian H. Hurd is an Assistant Professor in the Department of Agricultural Economics and Agricultural Business at New Mexico State University. Dr. Hurd earned his PhD and MS degrees in Agricultural Economics from the University of California, Davis, and holds a BA from the University of Colorado, Boulder.

Dr. Hurd is the author of numerous articles, book chapters and conference presentations on natural and environmental resource economics, water resource economics, and climate change vulnerability and adaptation. He is a delegate to the Universities Council on Water Resources (UCOWR), and is a member of the American Agricultural Economics Association, the Association of Environmental and Resource Economists, the American Water Resources Association, and the Western Agricultural Economics Association. 

Joel B. Smith, Stratus Consulting Inc.
Joel B. Smith is the Vice President of Stratus Consulting Inc. Mr. Smith received a BA from Williams College, and received an MPP from the University of Michigan.

Mr. Smith has examined climate change impacts and adaptation issues for the U.S. Country Studies Program, the U.S. Environmental Protection Agency, the U.S. Department of Energy, the U.S. Agency for International Development, the Office of Technology Assessment, the Electric Power Research Institute, the World Bank, the Global Environment Facility, the United Nations Environment Programme, and the International Institute for Applied Systems Analysis.

Before joining Stratus Consulting, Mr. Smith was the deputy director of the U.S. EPA's Climate Change Division. He was a coeditor of EPA's Report to Congress: The Potential Effects of Global Climate Change on the United States, published in 1989; As Climate Changes: International Impacts and Implications, published by Cambridge University Press in 1995; Adaptation to Climate Change: Assessments and Issues, published by Springer-Verlag in 1996; and Climate Change, Adaptive Capacity and Development published by Imperial College Press in 2003. Mr. Smith worked for the EPA from 1984 to 1992. Besides working on climate change issues, he also served as an analyst examining oceans and water regulations, and was a special assistant to the Assistant Administrator for the Office of Policy, Planning and Evaluation.

Brian Hurd
Joel Smith
William Easterling
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The Day After Tomorrow: Could it Really Happen?

 

The Day After Tomorrow: Could it Really Happen?

The movie The Day After Tomorrow is loosely based on the theory of “abrupt climate change.” The plot of the movie is that, as a result of global warming, ocean currents that circulate water around the world shut down, heating up the tropics and cooling the North Atlantic. The result is a catastrophic storm and a dramatic change in the global climate.

In the movies, abrupt climate change can happen practically overnight. But when scientists talk about abrupt climate change, they mean climate change that occurs over decades, rather than the usual centuries.

While most of The Day After Tomorrow is safely in the realm of science fiction, there is some real science to back up concerns about potentially irreversible changes in our climate within a couple of decades that would affect our communities, health, infrastructure, and ecosystems.

There are a number of potential “tipping points” in the Earth’s climate system – when a threshold could be crossed, resulting in substantial change. The National Research Council report Abrupt Impacts of Climate Change: Anticipating Surprises identifies potential abrupt changes in the ocean (which could result in rising sea levels and influence ocean circulation), the atmosphere (which could increase the frequency and intensity of extreme events), at high latitudes (including loss of Arctic sea ice), and ecosystems (species shifts, extinctions, and rapid state changes).

More on global warming and abrupt climate change:

C2ES Resources:

Additional Resources:

What climate impacts are happening now?

The current pace of global warming, spurred by the human release of greenhouse gases into the atmosphere, brings an increased risk of more frequent and intense heat waves, higher sea levels, and more severe droughts, wildfires, and downpours.

Drought. Global warming will increase the risk of drought in some regions. Also, warmer temperatures can increase water demand and evaporation, stressing water supplies. Learn about the links between climate change and drought.

Heat waves. As the Earth warms, more areas will be at risk for extreme heat waves. Learn about the link between climate change and extreme heat, the other risks heat waves can spawn, and what’s being done to adapt.

Tropical storms and hurricanes. A warmer world will help fuel the development of some of the strongest hurricanes

Arctic melting. Warming has increased Arctic temperatures at about twice the global rate, and Arctic sea ice cover has been shrinking much faster than scientists anticipated. Our Arctic Security report explores how this can set the stage for international disputes.

Wildfires. The number of large wildfires and the length of the wildfire season have been increasing in recent decades. Find out how climate change will worsen wildfire conditions.

Heavy Precipitation. Heavy downpours and other extreme precipitation are becoming more common and are producing more rain or snow. Learn more about the link between heavy precipitation and climate change.

 

A Synthesis of Potential Climate Change Impacts on the U.S.

Synthesis Impacts small cover

A Synthesis of Potential Climate Change Impacts on the U.S.

Prepared for the Pew Center on Global Climate Change
April 2004

By Joel B. Smith, Stratus Consulting, Inc.


Press Release

Download Report (pdf)

Foreword

Eileen Claussen, President, Pew Center on Global Climate Change

Greenhouse gas emissions—primarily from human activities such as the burning of fossil fuels— are causing changes in the global climate. Global temperatures increased approximately 1°F over the 20th century, and additional warming of 2.5-10.5°F is projected over the next century. The consequences of this warming for the United States will be significant. Natural resources and wildlife are dependent upon climate, as are the economy and human health.

Since 1998, the Pew Center has been chronicling the projected impacts of climate change on important economic sectors, human health, and natural resources. A Synthesis of Potential Climate Change Impacts on the United States by Joel B. Smith of Stratus Consulting Inc. is the eleventh in a series of reports examining the potential impacts of climate change on the U.S. environment. This report provides a synthesis of prior Pew Center reports regarding climate change impacts across a number of sectors and regions. This culmination of our Environmental Impacts series is being released with a companion report in our Economics series entitled U.S. Market Consequences of Global Climate Change, which provides an in-depth analysis of the market implications of climate change for the U.S. economy. This synthesis reveals:

• Natural systems are more vulnerable to climate change than societal systems. Species and ecosystems have limited ability to adapt to climate change, and as a consequence, U.S. biodiversity is likely to suffer. Managed sectors such as agriculture and forestry may avoid or reduce some adverse effects of climate change, but this adaptation will not be perfect or cost-free.

• Some U.S. regions are more vulnerable than others to climate change. The southern United States appears more vulnerable to the adverse effects of climate change than the North, due in large part to its low-lying coastal areas and the sensitivity of southern agriculture and forestry to warmer and dryer conditions. In the North, these sectors may benefit from longer growing seasons, but these benefits may not be sustained at higher magnitudes of warming. Warming may also reduce winter energy costs in the North, but it will increase cooling costs and the risk of heat-related illness and death in northern cities.

• Economic studies suggest that the market consequences of low-to-moderate warming will be approximately ±1 percent of U.S. gross domestic product (GDP). However, studies also indicate that any net economic benefit of climate change peaks at relatively low levels of warming, beyond which benefits decline and damages begin to accrue.

• The rate and magnitude of future climate change will be important. Gradual, moderate changes in climate would provide some opportunity for both natural and societal systems to adapt. In contrast, rapid or large changes in climate would increase the risk of large-scale, irreversible disruption of Earth’s environment, such as a shutdown of the thermohaline circulation or the collapse of the West Antarctic ice sheet.

Finally, while this series examines the impacts of climate change on the United States, we are mindful that other parts of the world will experience more severe consequences due to their location, physical characteristics, or economic limitations that impair their ability to adapt.

The author and the Pew Center gratefully acknowledge the input of Drs. Anthony Janetos, Neil Leary, Robert Mendelsohn, Lou Pitelka, Victor Kennedy, Stephen Schneider, and Roger Sedjo on this report.

Executive Summary

Since the 18th century, widespread deforestation and a steady increase in the use of fossil fuels have caused substantial concentrations of carbon dioxide and other greenhouse gases to accumulate in the atmosphere. The warming effect of these gases has caused the global climate to change. Over the past century, average global surface air temperatures increased by 0.6°C (1.1°F). This global warming will continue well into the future, and is likely to accelerate, as long as greenhouse gas concentrations in the atmosphere continue to rise. Although the exact magnitude and rate of future climate change remain uncertain, it will undoubtedly have far-reaching consequences for the United States, its natural resources, and economy.

This report builds on the Environmental Impacts Series published by the Pew Center on Global Climate Change, which reviews the current state of knowledge regarding how climate change will affect a number of economic and natural resource sectors in the United States. Reports in the series have included assessments of how climate change will affect water resources; agriculture and forestry; human health; and terrestrial, aquatic, and marine ecosystems. This report also draws on recent assessments of the potential impacts of climate change on the United States, particularly the U.S. National Assessment and reports prepared by the United Nations Intergovernmental Panel on Climate Change. Recent published literature regarding the implications of climate change for the U.S. economy is also discussed.

While the research completed to date indicates there are substantial uncertainties regarding exactly how climate will change and how it will affect society and ecosystems, it is possible to draw some conclusions about the vulnerability of the United States as a whole and the relative vulnerability of different regions, economic sectors, and natural ecosystems.

1. Natural ecosystems appear to be quite vulnerable to climate change. Climate change threatens to result in the loss of many coral reefs, coastal wetlands, endangered species (particularly those with limited range and mobility), cool- and cold-water fish, and boreal and alpine forest species. In addition, many species associated with particular regions, such as maple trees in New England, may not persevere in their current locations. In general, species are expected to attempt to migrate to higher latitudes or altitudes. This threat to natural ecosystems is distinctly more severe because development has reduced species populations, fragmented ecosystems and placed them under stress from pollution, and introduced barriers to migration, such as communities, farms, roads, and dams. Thus, biodiversity in the United States is likely to be reduced by climate change.

2. A number of sectors of the U.S. economy have a high sensitivity to climate change. Agriculture will be directly affected by changes in temperature and precipitation, and by ensuing effects on the distribution of pests and diseases and availability of water supplies for irrigation. Growth of forests will be sensitive to changes in climate, pests, and disease. Low-lying coastal areas will be at risk from inundation by rising seas. In addition, coastal communities, particularly along the Gulf and East coasts, will face increased risk of inundation, beach erosion, and property damage should the intensity or frequency of coastal storms and hurricanes rise. Human health in the United States will be affected by increased risk of heat stress, decreased risk of some cold weather mortality (although this has not been quantified), potential increases in transmission of infectious diseases, and changes in extreme weather events such as floods. The nation’s water resources will be affected by changes in supply resulting from altered precipitation patterns, earlier snowmelt, and increased evaporation. The risks of drought and floods are likely to increase in some areas. In addition, demand for water is likely to change, and may increase in many locations.

3. The capacity of the U.S. economy as a whole to adapt to a limited amount of climate change, with generally small impacts, appears to be quite high. The country’s high per capita income, relatively low population density, stable institutions, research base, and health care system give the United States a strong capacity to adapt to climate change. Thus, the country has a relatively large capacity to absorb its adverse effects. This does not mean there will be no cost for adaptation. Indeed, changing water resources management and agricultural practices and protecting coastal areas over this century could cost hundreds of billions of dollars. But, relative to the U.S. economy, these adaptation costs appear to be small and can most likely be absorbed. Finally, the country’s large size and the population’s mobility give it advantages in adapting to climate change. The lower 48 states span more than 20 degrees of latitude in the temperate climate zone, so while some southern parts of the country are at relatively higher risk from climate change, more northern areas are at less risk or may have many benefits. In addition, the American people are very mobile: in the 20th century there were large migrations to the North (early in the century), the West (throughout the century), and the South (later in the century). In contrast, many developing countries may experience adverse effects from climate change largely because their capacity to adapt to its impacts is limited. Indeed, it is not appropriate to extrapolate the findings for the United States to other countries.

4. Although the nation as a whole has a high capacity to adapt, sectors differ in their vulnerability. Sectors that can change the fastest, such as agriculture, are likely to be able to adapt best to climate change. Sectors with long-lived infrastructure and investments, such as water resources and coastal resources, may have more difficulty adapting and could experience some adverse impacts. However, their ability to adapt to a limited amount of climate change in the long run appears to be high. As noted above, natural ecosystems have a much more limited capacity to adapt to climate change compared to societal sectors, which is exacerbated by development and other human stressors.

5.  Different regions of the United States vary in their vulnerability to climate change. The southern United States is, on the whole, more vulnerable than the northern United States. The Southeast and southern Great Plains appear to be the most vulnerable regions because of their low-lying coasts, the potential loss in competitiveness of the agriculture and forest sectors (favorable climate zones for production will shift north), the increased risk of spread of infectious disease (although a strong public health system is likely to contain any potential increase), and especially the potential for reduced water supplies and increased demand for water. This would affect the availability of water for agriculture and instream uses such as protection of aquatic ecosystems. In contrast, northern areas could see mixed effects. While their low-lying coastal areas are at risk from sea-level rise and they (like the rest of the country) would have reduced biodiversity, northern areas could economically benefit from increased agricultural and forestry production and reduced energy costs. As noted below, these economic gains are transient and will not necessarily continue as temperatures keep rising.

6.  Even within regions that may have net economic benefits, individual communities and people could be adversely affected. Some populations are at particular risk because their location or vocation exposes them to changes in climate, and their low income constrains their ability to adapt. For example, the elderly poor in northern inner cities are at risk of increased heat stress during more extreme heat waves and generally have limited means of reducing the risk with air conditioning. In addition, many Native American communities may be at risk because they are heavily dependent on natural resources that will be affected by climate change, lack the financial resources to cope, and are not able to easily move to new locations.

7.  Studies of the economic impacts of climate change indicate that impacts for a few degrees of warming will be less than ±1 percent of gross domestic product (GDP). These studies attempt to incorporate major market and nonmarket (e.g., biodiversity and quality of life) impacts and assume a gradual change in climate and no change in variability. The direction of impacts (i.e., positive or negative) reported in various economic analyses differs, particularly depending on when the studies were conducted. Economic studies based on impact assessments conducted during the late 1980s and early 1990s tend to show damages of about one percent of GDP. More recent studies that consider new findings on the biophysical impacts of climate change and fully account for the potential for adaptation yield different results. These economic studies suggest that for up to 2-4°C (4-7°F) of warming, there could be net economic benefits of less than one percent of GDP. It is possible that because of factors not considered, such as change in variability or the magnification of impacts across related sectors, or less efficient adaptation than assumed in many recent studies, economic impacts could be more negative than these studies estimate. v A synthesis of potential U.S. climate change impacts A synthesis of potential U.S. climate change impacts.

8.  Economic impacts studies indicate that while there could be benefits, which peak at a few degrees of warming, there would be damages at higher levels of warming.Economic studies indicate that even in those sectors, such as agriculture, estimated to benefit from a small magnitude of warming, benefits peak and subsequently decline. This is because beyond certain increases in temperatures, crop yields decline or the “carbon fertilization” effect, which enables plants to grow more and use less water, saturates at higher carbon dioxide concentrations. In addition, other transient benefits such as reduced energy demand eventually become reversed as costs for cooling rise and savings from less heating are reduced. This is even true for regions such as the northern United States, which may experience economic benefits from a warming of less than several degrees, but losses beyond that. Economic studies suggest that national benefits peak at approximately a 1-2°C (2-4°F) increase in mean temperature. Beyond this, benefits decline until net economic damages occur at a warming of approximately 2-4°C (4-7°F) and become progressively worse with further increases in temperature. Significant uncertainty exists about the level of increased temperature that leads to damages and the magnitude of damages beyond that point.

9.  The rate and path of climate change matter. A gradual and monotonic change in climate (e.g., steady increases or decreases in precipitation) will be much easier to adapt to than rapid changes in climate or increased interannual or interdecadal climate variability. In a slowly and steadily changing climate, such adaptations as replacing infrastructure and introducing new technologies can be made gradually. A faster change in climate may necessitate more rapid than normal investments in infrastructure, technology, and other adaptations. Additional risk comes from changes in interannual or interdecadal variability.

10.  Increased warming heightens the risk of triggering large-scale changes to the climate system. Substantial increases in global mean temperature can set off large-scale changes to the earth’s climate system such as a shutdown of the thermohaline circulation (i.e., the Gulf Stream) or melting of the West Antarctic ice sheet. The thresholds are uncertain (and for some of these events may be quite high), the timeframes of the consequences of such events may take centuries to be fully realized, and the consequences are not well understood. However, it is possible that warming in the 21st century could trigger such events. Once started, they may be extremely difficult, if not impossible, to reverse. The consequences of such events have not for the most part, been studied, but could be substantial.

Conclusion

In spite of the uncertainties about climate change, we can, based on the Pew Center on Global Climate Change report series and other literature, draw some conclusions about the relative vulnerability of sectors and regions. As noted above, we are unable to predict the exact effects of climate change, but we are improving our understanding of the sensitivity of various sectors to climate change. Thus, these conclusions should be treated as preliminary.

1) Natural ecosystems appear to be quite vulnerable to climate change. Many natural resources are currently under stress, and climate change could impose additional stress. Climate change threatens to result in the loss of many coral reefs, coastal wetlands, endangered species (particularly those with limited range and mobility), cool- and cold-water fish, boreal species, and alpine species. This threat to natural ecosystems is distinctly more severe because development has reduced species populations, fragmented ecosystems and placed them under stress from pollution, and introduced barriers to migration, such as communities, farms, roads, and dams.

2) A number of sectors in the United States have a high sensitivity to climate change. Climate change could inundate many low-lying coastal areas, put urban areas at risk from increased storms and hurricanes, substantially change runoff in many basins, significantly change crop yields, and result in large geographic shifts and changes in the productivity of terrestrial and aquatic species.

3) The capacity of the U.S. economy as a whole to adapt to a limited amount of climate change, with generally small impacts, appears to be quite high. The country’s high per capita income, relatively low population density, research base, institutions, and health care system give the United States a strong capacity to adapt to climate change. There will be costs for adaptation, but relative to the U.S. economy, these costs appear to be small and can most likely be absorbed. Finally, the country’s large size and the population’s mobility give it advantages in adapting to climate change.

4) Although the nation as a whole has a high capacity to adapt, sectors differ in their vulnerability. Sectors that can change the fastest, such as agriculture, are likely to be best able to adapt to climate change. Sectors with long-lived infrastructure and investments, such as water resources and coastal resources, may have more difficulty adapting and could experience some adverse impacts. However, their ability to adapt to climate change in the long run appears to be high. In contrast, natural ecosystems have a much more limited capacity to adapt to climate change compared to societal sectors.

5) The southern United States is, on the whole, more vulnerable to climate change than the northern United States. Regions such as the Southeast and Southern Great Plains appear to be more vulnerable to climate change than the nation as a whole. In some regions, specific sectors, such as water resources in the Southwest, are at particular risk from climate change.

6) Even within regions that may have net economic benefits, individual communities and people could be adversely affected. Those with limited financial resources and mobility may be at greatest risk to climate change. The urban poor appear to have the highest risk from increased heat stress. Poor farmers may be most vulnerable to changes in agricultural conditions. Poor and isolated populations, such as Native Americans, may be at risk should climate change substantially affect the natural resources on which they depend.

7) Studies of the economic impacts of climate change indicate that impacts for a few degrees of warming will be less than ±1 percent of gross domestic product (GDP).These studies tend to incorporate both market and nonmarket (e.g., biodiversity and quality of life) impacts and, as noted above, assume a gradual change in climate and no change in variability. Economic studies based on impact assessments conducted during the late 1980s and early 1990s tend to show damages of about 1 percent of GDP. More recent studies that consider new findings on the biophysical impacts of climate change and fully account for the potential for adaptation yield different results. These economic studies suggest that for up to 2-4°C (4-7°F) of warming, there could be net economic benefits of less than 1 percent of GDP. It is possible that because of factors not considered, economic impacts could be more negative than these studies estimate.

8) Economic impacts studies indicate that while there could be benefits from climate change, which peak at a few degrees of warming, there would be damages at higher levels of warming. Economic studies indicate that even in those sectors, such as agriculture, estimated to benefit from a small magnitude of warming, these benefits peak and subsequently decline. This is because beyond certain increases in temperatures, crop yields decline or the “carbon fertilization” effect, which enables plants to grow more and use less water, saturates at higher CO2 concentrations. In addition, other transient benefits such as reduced energy demand eventually become reversed as costs for cooling rise and savings from less heating are reduced. This is even true for regions such as the northern United States, which may experience economic benefits from a warming of less than several degrees, but losses beyond that. Economic studies suggest that benefits peak at approximately a 1-2°C (2-4°F) increase in mean temperature. Beyond this, benefits decline until net economic damages occur at a warming of approximately 2-4°C (4-7°F) and become progressively worse with further increases in temperature. Significant uncertainty exists about the level of increased temperature that leads to damages and the magnitude of damages beyond that point.

9) The rate and path of climate change matter. A gradual and monotonic change in climate (e.g., steady increases or decreases in precipitation) will be much easier to adapt to than rapid changes in climate or increased interannual or interdecadal climate variability. In a slowly and steadily changing climate, such adaptations as replacing infrastructure and introducing new technologies can be made gradually. A more rapid change in climate may necessitate more rapid than normal investments in infrastructure, technology, and other adaptations. These investments could be costly.

10) Increased warming heightens the risk of triggering large-scale changes to the climate system. Substantial increases in global mean temperature could set off large-scale changes to the earth’s system such as shutdown of the thermohaline circulation (i.e., the Gulf Stream) or melting of the West Antarctic ice sheet. The thresholds are uncertain (and for some of these events may be quite high), the time frames of the consequences of such events may take centuries to be fully realized, and the consequences are not currently well understood. However, it is possible that warming in the 21st century could trigger such events. Once started, they may be extremely difficult, if not impossible, to reverse.

Joel Smith
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Overcoming the Barriers to Action

CLIMATE CHANGE: OVERCOMING THE BARRIERS TO ACTION

Remarks by Eileen Claussen

Earth’s Future: Taming the Climate
Columbia University Symposium

April 23, 2004


Thank you very much.  It is a pleasure to be here to celebrate Columbia University’s 250th anniversary.  So let me begin by saying Happy Birthday to one of the world’s finest institutions of higher learning.

On the flight here today, I was thinking about the next 250 years and wondering what will become of Columbia and the wider world in that time. (Given the topic we are here to discuss, along with projections that Manhattan could well be threatened by sea level rise in the years ahead, I decided that Columbia always has a future as a great underwater oceanographic institution.  So all is not lost.)

Yesterday, as all of you know, was Earth Day—or, as the Bush administration referred to it, Thursday, April 22nd.  The 34th anniversary of Earth Day, I believe, provides an important opportunity to acknowledge how far we’ve come since the 1970s.  Our air and water are cleaner, and we have laws to control pesticides, ocean dumping, and hazardous waste disposal.  On the other hand, we still have to endure the music of long-lasting 70s rock bands such as Aerosmith and Kiss.  So I suppose things have not universally improved.  (My apologies to all of the Aerosmith and Kiss fans in the audience.)

Seriously, we have made significant progress on environmental issues since the 1970s—but, obviously, not nearly enough.  And I commend you for commemorating Earth Day yesterday in such an appropriate and public-spirited way, by focusing your attention on an issue where we have not seen significant progress: global climate change. 

During the first day of this symposium, you heard from Michael McElroy and a number of distinguished panelists about the state of our knowledge regarding the climate change issue.  You heard about trends in global temperatures and what this means for the climate.  You heard about ways we can possibly adapt to the predicted changes.  And you heard some ideas about what can be done to slow down or stop climate change. 

My job in this symposium is to try to explain why humanity is doing so little to prepare for the certainty of climate change.  And, because I am genetically programmed to focus on solutions, I will also lay out some ideas for an overall approach that might help us chart a productive path forward on this issue. 

But first a very brief refresher course on why we are here.  We are here because there is overwhelming scientific evidence on three basic points: one, the earth is warming; two, this warming trend is likely to worsen; and three, human activity is largely to blame.

And so the question is: if we know these three things, why are we not acting on that knowledge?  Why are we not doing more to limit those human activities that are the driving force in climate change—namely, our emissions of greenhouse gases stemming primarily from the burning of fossil fuels?

The answer, very frankly, is because we have allowed ourselves to be swayed by a number of tired excuses—excuses put forward, for the most part, by people and interests who plainly want nothing to happen to address the problem of climate change.  The reason, more often than not, is that they have an economic interest in the status quo. 

The first excuse for inaction usually revolves around the issue of scientific uncertainty.  Even though we know that the earth is warming, that the warming will get worse, and that human activities are largely to blame, the fact that we cannot accurately predict exactly how much warming we will see or how quickly it will happen is used unfailingly as a reason for inaction. 

But I submit to you that uncertainty in the science is not a valid reason to hold off on addressing this problem, given what we do know.  The fact that we are uncertain about exactly how climate change will proceed may actually be a reason to act sooner rather than later.  And I will tell you why:

First, current atmospheric concentrations of greenhouse gases are the highest in more than 400,000 years.  This is an unprecedented situation in human history, and there is a real potential that the resulting damages will not be incremental or linear, but sudden and potentially catastrophic.  Acting now is the only rational choice under these circumstances. 

· A second reason to act now is that the risk of irreversible environmental impacts far outweighs the lesser risk of unnecessary investment in reducing or mitigating greenhouse gas emissions.

· Third, it is going to take time to figure out how best to meet this challenge--both the technology and the policy responses.  We must begin learning by doing now.

· Fourth, the longer we wait to act, the more likely it is that the growth in greenhouse gas emissions will continue, and that we will be imposing unconscionable burdens and impossible tasks on future generations.

· Fifth, there is an obvious lagtime between the development of policies and incentives that will spur action and the results.  So even if we do not wait, we will be waiting. 

· And, last but not least, we can get started now with a range of actions and policies that have very low or even no costs to the economy.

This brings me to the second tired excuse that is used to argue for inaction in the face of climate change: the costs will be too high.  This argument ignores the fact that if we do this right—and if we start sooner rather than later—we can minimize those costs.  And, more important, we can minimize the very real economic costs of doing nothing.

Next week, the Pew Center will be releasing a report that weighs the potential costs of climate change in relation to the potential benefits.  Yes, in the short term, there may be scattered economic benefits in sectors such as agriculture resulting from higher temperatures and more rainfall.  However, our research shows that these benefits begin to diminish and eventually reverse as temperatures continue to rise.  In other words, the potential economic damage from climate change far outweighs any short-term economic gain.

What kind of economic damage are we talking about?  In 2002, the United Nations Environment Program released a report done in collaboration with some of the world's largest banks, insurers and investment companies. The report found that losses resulting from natural disasters appear to be doubling every 10 years and, if this trend continues, will amount to nearly $150 billion over the coming decade.

Over the last two years alone, we have seen horrific wildfires in the western United States and devastating flooding in central Europe and China. These are the kinds of events scientists predict will occur more frequently or with more intensity in response to climate change.  Of course, it is impossible to conclusively link any one of these disasters to the broader warming trend, but we may be getting an idea of what’s to come.  And we cannot allow those who argue that addressing this problem will cost too much to ignore the potentially devastating costs of allowing climate change to proceed unchecked.

What’s more, the costs of acting to address climate change can be kept at a manageable level—if we use economic instruments wherever possible; if we act thoughtfully and in phases, so that we allow for capital stock turnover and the development of new technologies; and if we provide certainty for the private sector to make wise investments and create new climate-friendly businesses. 

Responding to climate change does not have to wreak economic havoc.  A recent MIT study assessing the costs of the Lieberman-McCain Climate Stewardship Act found that a modest, national emissions trading system would cost less than $20 per household per year.  In addition, a significant number of companies are showing that they can meet ambitious targets for reducing their emissions—targets of 10 percent, 25 percent, even 65 percent below 1990 levels—at minimal or no cost.  I repeat: at minimal or no cost.   Some companies are even saving money.  For example recently announced that it had achieved its target of a 10-percent reduction in emissions eight years ahead of schedule—and at a savings of roughly $600 million due to more efficient energy use and streamlined production processes.

So while I would not argue that addressing climate change over the next 50 years is free, I do believe that with care and pragmatism, we can do what we need to without breaking the bank. Cost should not be a reason not to act.

A third excuse that we have allowed to stifle action against climate change is that the United States should not be asked to bear the economic costs of reducing our emissions while other countries, notably China and India, get a quote-unquote “free ride.”  In other words, why should we have to do all this hard work if other people do not?

This argument is weak enough when you consider that we can reduce our emissions in economically feasible ways.  It’s weaker still when you recognize that the United States already is lagging behind in the global technology race, with big implications for U.S. jobs.  Our dallying over climate policy is ceding to Europe and Japan – which have already agreed to emission caps – the lead in developing climate-friendly technologies.  And I say we should worry less about China and India attracting the polluting technologies of the last century, and worry more that we won’t be selling them the technologies of the 21st century. 

The fact that developed countries should act first to reduce their emissions is enshrined in the United Nations Framework Convention on Climate Change (which the United States is a party to, thanks to the signature of our first President  Bush: George H.W.).  Why did the United States agree to this?  Because developed countries are responsible for most of the greenhouse gases in the atmosphere and therefore should reduce their emissions first.  And, because developed countries are far wealthier than developing countries, we have the means to take action now.  

This is not to say, of course, that developing countries should have no responsibilities.  Just as the United States and other developed nations will need to become more carbon-friendly as we turn over our capital stock, so must developing countries develop in more carbon-friendly ways.  But to expect, or even to wish, that developing countries should face emission limits at the same time and on a similar scale as we do is folly. 

We have now touched on three main excuses for doing nothing: the science is uncertain; the economic costs of addressing this issue are too high; and developed nations should not be asked bear this burden first.  All of these excuses are used to delay action on this issue.  In pushing for such a delay, people often resort to a fourth excuse that underlies all of the others: we can solve this problem if and when we really have to.  But until then, leave us alone.  This is what I call the “silver-bullet defense.” 

Americans, by nature, are an optimistic people who have a deeply held faith in their ability to apply their down-home ingenuity to solve every problem that comes along.  We live in a world of wrinkle-erasing botox injections, iron-free shirts and cellular phones with cameras built-in.  We’ve got to be able to come up with an equally wondrous technology to solve this problem of global warming.  Just give us time. 

There are two problems with this argument.  First, we don’t have time.  You cannot launch an industrial revolution overnight—and that is exactly what we need: another industrial revolution.  Second, climate change is too big a challenge for any one solution.  It is going to take a wide-ranging portfolio of technologies, from energy-efficiency technologies and hydrogen to carbon sequestration, renewable fuels, coalbed methane, biofuels, nanotechnology and biotechnology.  Developing these technologies and getting them to market is going to take a lot of hard work.  We cannot just snap our fingers and make it happen.

We need to replace our existing energy system.  Businesses, however, continue to receive mixed signals from policy-makers about whether or not we are serious about getting on with the challenge of weaning ourselves from fossil fuels.  What’s more, the federal government spends even less than the private sector on energy-related RD&D, which is particularly disappointing when you consider the importance of energy to our economy, our security and our  environment. 

We can do better than this.  We need to encourage, perhaps even require, the development of the full complement of technologies—some of which we may not even know about yet—that will begin to deliver real reductions in greenhouse gas emissions. 

In the same way that we need a broad portfolio of technologies, we will need an array of policy solutions as well. 

Among the most important of these is an economy-wide cap-and-trade system.  This is a policy that sets targets for greenhouse gas emissions and then allows companies the flexibility to trade emission credits in order to achieve their targets in the most economic manner.  This is the approach taken in the Climate Stewardship Act introduced last year by Senators Joseph Lieberman and John McCain.  Their bill garnered the support of 43 U.S. senators and prompted the first serious debate in Congress about exactly what we need to be doing to respond to the problem of climate change.  (A companion measure was introduced in the House of Representatives just last month.) 

But a cap-and-trade policy alone is not enough.  We also need an aggressive R&D program, government standards and codes, public infrastructure investments, public/private partnerships, and government procurement programs—and I am sure there are policies we haven’t even thought of yet.  However, despite needing all these policies, we still seem to be waiting for an easy, catch-all answer that will get us out of this mess, just as we are waiting for a technology silver bullet to make the problem go away overnight.  And waiting itself becomes yet another excuse for doing nothing. 

But in doing nothing, we are making a choice.  We are choosing to ignore what we know to be true—namely, that the earth is warming, that this warming is getting worse, and that human activity is largely to blame.  We are choosing to leave as our bequest to future generations a world that will, in all likelihood, be very different from the world we live in today.  We are choosing to saddle our children and our children’s children with an array of problems that may well be beyond their ability to solve.

This is not a case, in other words, where inaction can be explained in terms of benign neglect—“we just didn’t know.”  Atmospheric levels of carbon dioxide, the major greenhouse gas, have reached an all-time high, according to a report last month from the National Oceanic and Atmospheric Administration.  By putting off serious action, we are essentially making a conscious decision to make the problem worse.  And for that, there is really no excuse. 

Of course, it doesn’t have to be this way.  There are indeed many smart and inexpensive steps we can take beginning right now to reduce our greenhouse gas emissions and start developing the low-carbon energy technologies of the future. 

How can we start?  Here are a few ideas—things we can do to lay the groundwork for reduced emissions, increased energy efficiency and improved energy security in the years ahead:

· Number One: We can require companies to track and disclose their greenhouse gas emissions.  If it is true that what is measured is managed, then this is an essential step if we ever want to move forward with any kind of program for reducing emissions. 

· Number Two: We can use a standard-setting process to set practical but progressive goals to improve the efficiency of our vehicles and our appliances.

· Number Three: We can make strategic public investments in promising technologies.
· Number Four: We can provide incentives for farmers and foresters to adopt practices that take carbon from the atmosphere and store it in soil, crops and trees.

· Number Five: We can step up efforts to determine whether we can safely and permanently sequester carbon in geologic formations deep underground at a reasonable cost.

· And Number Six: As I mentioned already, we can build an economy-wide system that sets modest but mandatory targets for reducing emissions and uses market approaches like emissions trading to meet them at the lowest possible cost.

That’s just a random assortment of things we can do right now.  And none of these activities—not one—would pose any kind of serious threat to U.S. economic performance.  Indeed, by creating the conditions for a new industrial revolution that encourages the development and deployment of low-carbon energy technologies, we can create new opportunities, new jobs, and new wealth. 

The key as we move forward is to set a clear, long-term goal of where we want to be on this issue, and then to figure out the short- and medium-term steps that will get us there.  At the Pew Center, we call it the “10-50 Solution.”  By 10-50, we mean that we believe this is a 50 year issue and we should be thinking ahead and envisioning what our society and our economy will need to look like if we are to significantly reduce our emissions. 

That’s the “50” part.  Then, in order to make it manageable, we break it down into 10 year increments.  And we identify the policies and strategies we can start pursuing in the next ten years and the decades to come so we can achieve our long-range goal.

That’s the “10” part.

The 10-50 approach takes a long-term view because we know it will take time to achieve the result that we need -- a low carbon economy.
 
At the same time, the 10-50 approach enables us to identify the practical steps we can take in the short-term and in the decades to come so we can achieve steady progress. 

If we do this right, one step at a time with a long term goal -  it will be like Calvin from Calvin & Hobbes who said,  'Know what's weird?  Day by day, nothing seems to change, but pretty soon…everything's different'.

In closing, let me say again that I greatly appreciate the opportunity to be here today.  And I ask all of you to join with me and the Pew Center in saying that the time is past for making excuses about why we should not or cannot take serious action to address the problem of global climate change.  With an approach based on sound science, straight talk, and a commitment to working together to protect the climate while sustaining economic growth, we can achieve real progress on this issue.  And we must. 

Columbia University is 250 years old this year.  Let’s work together to ensure that, 250 years from now, there will be a symposium at this great university on what happened at the dawn of the 21st century to finally get a handle on this enormous problem. 

Thank you very much.  

Press Release: Global Warming Expected to Further Degrade Coral Reef Systems

For Immediate Release:
February 13, 2004
                                                             
Contact:  Katie Mandes
(703) 919-2293

Global Warming and Coral Reefs

Global Warming Expected to Further Degrade Coral Reef Systems

 
Washington, DC — Coral reefs have the highest biodiversity of any marine ecosystem, providing important ecosystem services and direct economic benefits to the large and growing human populations in low-latitude coastal zones.  One recent estimate valued the annual net economic benefits of the world’s coral reefs at $30 billion. But human activities including development in coastal areas, over-fishing, and pollution have contributed to a global loss approaching 25 percent of these valuable ecosystems.  Global warming is expected to further contribute to coral reef degradation in the decades ahead.  

A new Pew Center on Global Climate Change report, Coral Reefs & Global Climate Change: Potential Contributions of Climate Change to Stresses on Coral Reef Ecosystems, authored by Drs. Robert W. Buddemeier, Joan A. Kleypas, and Richard B. Aronson, outlines the likely impacts of climate change and global warming over the next century to coral reef systems both in U.S. waters and around the world. The report reviews the published literature in an effort to analyze the current state of knowledge regarding coral reef communities and the potential contribution of future climate change to coral reef degradation and loss.

The report concludes that recent global increases in reef ecosystem degradation and mortality (the “coral reef crisis”) are exceeding the adaptive capacity of coral reef organisms and communities.  The severity of this crisis will only intensify with future changes in the global climate.    

“Coral reefs are striking, complex, and important features of the marine environment,” said Eileen Claussen, President of the Pew Center. “If we fail to act, the destruction of these rare and important ecosystems will continue unabated, threatening one of our world’s most precious natural resources.” 

Other major findings from the report include: 

Climate and localized, nonclimate stresses interact, often synergistically, to affect the health and sustainability of coral reef ecosystems.  Increases in ocean temperature contribute to coral bleaching episodes that cause coral mortality and stress, while future increases in atmospheric carbon dioxide may limit coral growth.  In addition to their direct effects, these stresses also act to degrade coral reefs by increasing their susceptibility to pollution, over-fishing, predation, and disease.  

Coral reef alteration, degradation, and loss will continue for the foreseeable future, especially in those areas already showing evidence of systemic stress.  There is no doubt that continued global warming will cause further degradation of coral reef communities.

The effects of global warming on global coral reef ecosystems will vary from one region to another.  Although climate change has the potential to yield some benefits for certain coral species in specific regions, such as the expansion of their geographic ranges to higher latitudes, most of the effects of climate change will be harmful rather than beneficial.   

While the net effects of climate change on coral reefs will be negative, coral reef organisms and communities are not necessarily doomed to total extinction.  The diversity of existing coral species, the acknowledged adaptation potential of reef organisms, the spatial and temporal variations in climate change, and the potential for human management and protection of coral reef ecosystems all provide scope for survival. 

Multiple environmental management strategies, from local to global, will be necessary to ensure the long-term sustainability of the world’s coral reef ecosystems. Efforts to reduce emissions of greenhouse gases that contribute to global warming can reduce the risk of future bleaching events and moderate changes in ocean chemistry.  Marine protected areas will protect coral reefs from nonclimate stresses and enable coral reefs to better adapt to the effects of global climate change.  

Part of “Impacts” Series:

Coral Reefs & Global Climate Change: Potential Contributions of Climate Change to Stresses on Coral Reef Ecosystems, was prepared for the Pew Center by a team of U.S. experts on coral reef ecosystems including Drs. Robert W. Buddemeier, Kansas Geological Survey; Joan A. Kleypas, National Center for Atmospheric Research; and Richard B. Aronson, Dauphin Island Sea Lab.  It is the tenth in a series of Pew Center reports examining the potential impacts of climate change on the U.S. environment.  Other Pew Center reports focus on domestic and international policy issues, global warming solutions, and the economics of global warming. 

A complete copy of this report and other Pew Center reports can be accessed from the Pew Center’s website: www.c2es.org.

###

The Pew Center was established in May 1998 by The Pew Charitable Trusts, one of the United States’ largest philanthropies and an influential voice in efforts to improve the quality of the environment.  The Pew Center is an independent, non-profit, and non-partisan organization dedicated to providing credible information, straight answers, and innovative solutions in the effort to address global climate change.  The Pew Center is led by Eileen Claussen, the former U.S. Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs.

Coral Reefs & Global Climate Change

Coral Reefs Small Report Cover

Coral Reefs & Global Climate Change: Potential Contributions of Climate
Change to Stresses on Coral Reef Ecosystems


Prepared for the Pew Center on Global Climate Change
February 2004

By:
Robert W. Buddemeier, Kansas Geological Survery
Joan A. Kleypas, National Center for Atmospheric Research
Richard B. Aronson, Dauphin Island Sea Lab


Press Release

Download Entire Report (pdf)

Joan A. Kleypas
Richard B. Aronson
Robert W. Buddemeier
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The Science of Climate Change: Global and U.S. Perspectives

The Science of Climate Change: Global and U.S. Perspectives

By:
Tom M. L. Wigley, National Center For Atmospheric Research

Press Release

Download Entire Report (pdf)

Download Report (ZIP file)

This report is available for download only.

Basic Science on climate change:

  • Projections of future climate change suggest a global temperature increase of 1 to 6°C (2 to 10°F) from 1990 to 2100, with warming in most of the United States expected to be even higher.
  • Current scientific research shows that climate change will have major effects on precipitation, evapotranspiration, and runoff — and ultimately on the nation's water supply
  • While the net impacts of a doubling of atmospheric CO2 concentrations on U.S. agriculture as a whole are likely to be small, the impacts are likely to vary considerably from region to region.
  • Climate change will lead to substantial sea-level rise along much of the U.S. coastline, due mostly to thermal expansion of the oceans.
  • The very real possibility exists that warming over this century will jeopardize the integrity of many terrestrial ecosystems and will pose a threat to our nation's biodiversity.

The Wigley report provides more information on how climate is influenced by anthropogenic factors. You may download a pdf of the entire report by clicking on the report cover above, or read portions of the report in html by following the links in the "In This Section" box.

Foreword

 

Eileen Claussen, Executive Director, Pew Center on Global Climate Change

This report on the science of climate change seeks to explain how climate is influenced by anthropogenic factors. Understanding the effect of greenhouse gas concentrations on the atmosphere is key to understanding the potential magnitude of the "greenhouse effect," evaluating possible environmental impacts, and considering policy responses.

A variety of factors determine the rate and magnitude of climate change, including the emissions of greenhouse and aerosol-producing gases, the carbon cycle, the oceans, biosphere, and clouds. As our understanding in each of these areas evolves, it is important that researchers, policy-makers, the press, and the public be kept informed since these developments affect our understanding of the seriousness and complexity of this issue.

As part of the Pew Center's series examining the potential impacts of higher atmospheric concentrations of greenhouse gases on the United States, this paper by the distinguished climate scientist Tom M.L. Wigley, senior scientist with the National Center for Atmospheric Research, addresses what is known and not known about the science of climate change. Its publication comes in an interim period between assessments of the science by the Intergovernmental Panel on Climate Change (which published its second assessment in 1996 and will publish its third assessment in 2001). The author uses preliminary estimates of greenhouse gas and sulfur dioxide emissions from the current IPCC review process as well as his own work to supplement previously published research.

The new research suggests the likelihood of slightly larger changes in temperature and sea level rise than projected in the most recent IPCC assessment. The temperature rise is expected to be greater in the U.S. than the average temperature increase across the globe. While changes in precipitation and extreme weather events such as hurricanes and other storms are more difficult to predict, it is possible that the intensity of rain and hurricane events could increase. Uncertainties in predicting the direction and magnitude of these changes make it difficult to predict the impacts of climate change. However, even small changes in climate can lead to effects that are far from trivial.

While the analysis presented is the work of one author, this report has been subject to extensive peer review. The Pew Center and the author are indebted to many scientists and organizations for their constructive comments on previous drafts of this paper or sections of this paper. Their comments have helped improve the text substantially, and so, while the opinions expressed in this report are solely those of the author, we gratefully acknowledge their input: E. Barron, B. Felzer, C. Hakkarinen, A. Henderson-Sellers, M. Hulme, M. MacCracken, M. McFarland, J. Mahlman, G. Meehl, N. Nakicenovic, B.D. Santer, M.E. Schlesinger, K.P. Shine, J.B. Smith, and S.J. Smith. The A1, A2, B1, and B2 scenarios developed in the current IPCC working group process have been used with the kind permission of their producers, represented by T. Morita, A. Sankovski, B. deVries, and N. Nakicenovic. D. Viner of the Climate Impacts LINK Project (UK Dept. of the Environment, Regions and Transport contract EPG1/1/68) supplied the HadCM2 data on behalf of the Hadley Centre and UK Meteorological Office. In addition, the Pew Center would like to acknowledge and thank Joel Smith and Brian Hurd of Stratus Consulting for their management of this Environmental Impacts series.

Executive Summary

 

The average surface temperature of the globe has warmed appreciably since the late 1800s, by about 0.6°C. Since this warming cannot be adequately explained by natural phenomena such as increased solar activity, human-induced increases in greenhouse-gas concentrations appear to be at least partly responsible. In addition to the warming effect of greenhouse-gas increases, however, changes in temperature over the past century are likely to have been significantly influenced by the cooling effect associated with changes in the sulfate aerosol loading of the atmosphere, arising from fossil-fuel-derived sulfur dioxide (SO2) emissions. When greenhouse-gas, sulfate aerosol, and solar influences are considered together, observed climate changes are consistent with model predictions.

Projections of future global-mean temperature and sea level change made by the Intergovernmental Panel on Climate Change (IPCC) in its 1996 Second Assessment Report used emissions scenarios developed in 1992. Preliminary versions of new emissions scenarios produced by the writing team for the IPCC Special Report on Emissions Scenarios (SRES) are now available. The most important difference between the old (1992) and new (SRES) scenarios is that the new scenarios have much lower emissions of sulfur dioxide. The reduction in sulfur dioxide emissions (and their attendant cooling effects through the production of sulfate aerosols) results in a slight increase in temperature and sea level rise projections from those previously given by the IPCC. If central estimates of model parameters are used, global-mean warming from 1990 to 2100 ranges from 1.9°C to 2.9°C. Sea-level rise estimates over the same period range from 46 to 58 cm. For temperature and sea level changes over the next few decades, projections are virtually independent of the emissions scenario.

Based on results from a number of climate models, the rate of future warming over the United States is expected to be noticeably faster than the global-mean rate. Future regional-scale precipitation changes are highly uncertain. The only result that is common to all climate models is an increase in winter precipitation in northern latitudes, from the northern Great Plains to the northeastern states. Even in the absence of large precipitation changes, there could still be significant changes in the availability of water for agriculture, human consumption, and industry because of the increased evaporation that should accompany warming. This factor alone would lead to drier summer soil conditions and reduced runoff. The effects of increased evaporation, however, may be partly offset by the direct plant-physiological effect that carbon dioxide (CO2) has in improving plant water-use efficiency and, hence, lowering evapotranspiration rates.

Changes in weather and climate extremes over the United States are certain to occur as the global climate changes. The frequency of extremely hot days is almost certain to increase, and the frequency of frosts should decrease. Changes in the frequency of daily precipitation extremes are highly uncertain, although there is evidence for an increase in the frequency of wet extremes. For hurricanes and tropical storms, the evidence suggests that there could be small increases in their windspeeds. It is also likely that future such storms will be accompanied by larger rainfall amounts. While there is no credible model-based information on changes in the number of hurricanes and tropical storms per year worldwide, there is empirical evidence that suggests that a small increase in frequency is possible in the North Atlantic region. For all extreme events, however, it is unlikely that the projected changes will become evident in a statistically convincing way for many decades, with the exception of temperature extremes, which should become evident sooner.

About the Author

 

Tom M.L. Wigley

Tom M.L. Wigley (B.Sc., Ph.D.), formerly Director of the Climatic Research Unit, University of East Anglia, Norwich, U.K., currently holds a Senior Scientist position with the National Center for Atmospheric Research, Boulder, CO. One of the world's foremost scientists in the area of climate change, he has published in diverse aspects of the broad field of climatology. His main interests are in carbon cycle modeling, projections of future climate and sea-level change, and interpretation of past climate change particularly with a view to detecting anthropogenic influences. Recently, he has concentrated on facets of the global warming problem, and has contributed on many occasions to Intergovernmental Panel on Climate Change (IPCC) reports and assessments.

 

Tom M. L. Wigley
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