Science

The Day After Tomorrow: Could it Really Happen?

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The movie The Day After Tomorrow is loosely based on the theory of “abrupt climate change.” As a result of global warming, the Gulf Stream (part of the Atlantic thermohaline circulation) shuts down. The North Atlantic region starts to cool while heat builds up in the tropics. The result is a severe storm, the likes of which have never been seen, and a dramatic change in the global climate.

Could this really happen? Get the facts from these frequently asked questions below:

What is an abrupt climate change?

Could an abrupt climate change really happen?

What is the difference between “global warming” and “climate change?”

Should we worry about global warming?

Do scientists agree about global warming?

What is the Atlantic thermohaline circulation?

Could climate change shut down the thermohaline circulation?

What are the chances of the thermohaline circulation shutting down?

How can global warming cause cold weather?

If “The Day After Tomorrow” is fiction, what is the truth about global warming?

What can be done about global climate change?

How can I learn more about climate change?

 

What is an abrupt climate change?

When scientists talk about climate change, they are usually referring to “gradual climate change.” In other words, if the planet warms steadily, the climate changes steadily. But there's evidence that some parts of the climate system work more like a switch than a dial: if a certain temperature level is reached, there may be an abrupt and large change in the climate. That’s why some scientists worry about a catastrophic event — like the breakup of the West Antarctic ice sheet or the collapse of the Atlantic thermohaline circulation. To download the National Research Council's Report in Brief on Abrupt Climate Change (PDF), click here.

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Could an abrupt climate change really happen?

Scientists have just begun to study the possibility of an abrupt climate change. But when scientists talk about abrupt climate change, they mean climate change that occurs over decades, rather than centuries. It’s too soon to know for certain whether abrupt climate change could occur, but if it does, it’s not expected to happen within the next several decades.

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What is the difference between “global warming” and “climate change?”

"Global warming" refers to the gradual increase of the Earth's average surface temperature, due to a build-up of greenhouse gases in the atmosphere. "Climate change" is a broader term that refers to long-term changes in climate, including average temperature and precipitation, as well as changes in the seasonal or geographic variability of temperature and precipitation.

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Should we worry about global warming?

This is the best time to worry about global warming, because there’s no longer any doubt in the scientific community that it’s happening, but if we act now, we can still avoid its worst consequences.

Global temperatures have increased by 1°F over the past 100 years. Although this may seem like a small change, it is enough to harm important ecosystems, change rainfall patterns and raise the sea level. Climate models project additional warming of about 2-10° F over the next 100 years. The overwhelming consensus of scientists who study the atmosphere is that this warming is caused primarily by the build-up of greenhouse gases (GHGs) in the atmosphere, mostly from the burning of fossil fuels like coal and oil.

The good news is that there are many ways to reduce GHG emissions inexpensively. Many states and businesses are already taking action. Senators McCain and Lieberman plan to reintroduce their Climate Stewardship Act in the Senate this year. A companion bill, the Gilchrest-Olver Climate Stewardship Act, is now being considered by the House.

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Do scientists agree about global warming?

Although scientists still argue about how fast and how much the atmosphere will warm, the mainstream scientific community agrees on three key points: the earth is warming; the warming is caused primarily by the build-up of GHGs in the atmosphere; and that the warming will continue if we don’t reduce GHG emissions.

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What is the Atlantic thermohaline circulation?

The Atlantic thermohaline circulation, which includes the Gulf Stream, acts like an oceanic conveyer belt that carries heat from the tropics to the North Atlantic region. Warm surface water from the tropics travels northward by the Gulf Stream. As the warm water cools in the North Atlantic, it sinks to the ocean floor, and then slowly moves southward until it returns once again to the tropics. This ocean circulation pattern is caused by differences in water temperature and salinity in the ocean.

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Could climate change shut down the thermohaline circulation?

Global warming is expected to increase ocean temperatures and to increase the flow of freshwater into the ocean through precipitation, run-off, and melting of glaciers. Many climate models have projected that increased surface ocean temperatures and reduced salinity could slow the thermohaline circulation. A few models have projected a complete shutdown of the thermohaline circulation in the case of severe global warming, but this is being debated by the scientific community.

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What are the chances of the thermohaline circulation shutting down?

We don’t yet know the probability of the thermohaline circulation shutting down. It depends on how much and how quickly the atmosphere warms. In general, it is considered possible but not very likely. If it were to occur, it would probably not happen within the next 100 years, and circulation would eventually recover, after decades or centuries.

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How can global warming cause cold weather?

Without the thermohaline circulation, not as much heat would be transported from the tropics to the North Atlantic region. We don’t know how much of this cooling would be balanced by the simultaneous warming in the atmosphere. While it is possible there would be cooling in the North Atlantic region, it is considered more likely that it would continue to warm, but more slowly than the rest of the world.

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If “The Day After Tomorrow” is fiction, what is the truth about global warming?

The truth is that global warming is happening and that it is already too late to avoid some of the effects. Even under the most optimistic circumstances, atmospheric scientists expect global climate change to result in increased flooding and droughts, more severe storms, and a loss of plant and animal species. These events will occur, even if climate change is gradual.

Our report, “A Synthesis of Potential Climate Change Impacts on the U.S.," summarizes the possible effects of global climate change on the natural resources and economy of the United States.

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What can be done about global climate change?

There is no single cause of global climate change and there is no single answer. Most experts believe that technology will provide the solutions. Technologies that reduce emissions (energy efficiency, hydrogen fuels, carbon storage, nuclear energy and renewable energy) and technologies that remove carbon from the atmosphere may all play a role. Government policies that encourage businesses to develop and use these and other technologies are also very important.

Many states and businesses have already found they can reduce emissions while saving money. See "Climate Change Activities in Congress" for a look at what is already being done at the state level, the national level, and in the business community. For a look at a national policy that would combat global warming, read about the Lieberman-McCain Climate Stewardship Act.

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How can I learn more about climate change?

For more detailed information, see our Science & Impacts section and a list of our reports released since 1998. For a good summary of the reasons the United States should join the rest of the world in addressing global climate change without delay, see Eileen Claussen’s Myths and Realities.

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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

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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

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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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Forests & Global Climate Change

forestrycover

Forests & Global Climate Change: Potential Impacts on U.S. Forest Resources

Prepared for the Pew Center on Global Climate Change
February 2003

By:
Herman Shugart, University of Virginia
Roger Sedjo, Resources for the Future
Brent Sohngen, The Ohio State University

Press Release

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Foreword

Eileen Claussen, President, Pew Center on Global Climate Change

Approximately one-third of U.S. lands are covered by forests, which makes forest ecosystems prominent natural resources that contribute to biodiversity, water quality, carbon storage, and recreation. Forests also play a significant role in the U.S. economy, and forestry or forestry-related enterprises are the dominant industries in many U.S. communities. Human-induced climate change over the next century is projected to change temperature and precipitation, factors that are critical to the distribution and abundance of tree species.

Forests and Global Climate Change is the ninth in a series of Pew Center reports examining the potential impacts of climate change on our environment and health. A previous report in this series addressed the risks to terrestrial ecosystems posed by climate change. This report details the likely ecological and economic impacts of climate change over the next century on the U.S. forestry sector. Key findings include:

Forest location, composition, and productivity will be altered by changes in temperature and precipitation. Climate change is virtually certain to drive the migration of tree species, resulting in changes in the geographic distribution of forest types and new combinations of species within forests. Generally, tree species are expected to shift northward or to higher altitudes. In addition, climate change is likely to alter forest productivity depending upon location, tree species, water availability, and the effects of carbon dioxide (CO2) fertilization.

Changes in forest disturbance regimes, such as fire or disease, could further affect the future of U.S. forests and the market for forest products. Increased temperatures could increase fire risk in areas that experience increased aridity, and climate change could promote the proliferation of diseases and pests that attack tree species. Such disturbances may be detrimental to forests themselves, but may have a lesser impact at the market level due to salvage operations that harvest timber from dying forests.

U.S. economic impacts will vary regionally. Overall, economic studies indicate that the net impacts of climate change on the forestry sector will be small, ranging from slightly negative to positive impacts; however, gains and losses will not be distributed evenly throughout the United States. The Southeast, which is currently a dominant region for forestry, is likely to experience net losses, as tree species migrate northward and tree productivity declines. Meanwhile, the North is likely to benefit from tree migration and longer growing seasons.

As a managed resource, the implications of climate change for the forestry sector are largely dependent upon the actions taken to adapt to climate change. The United States has vast forest resources and currently consumes less timber than grows within the country each year. If professional foresters take proactive measures to substitute thriving tree species for failing species, to relocate forestry industry to productive regions, and to salvage trees during dieback, the sector may minimize the negative economic consequences of climate change.

A number of challenges currently limit our understanding of the effects of climate change on forestry. Existing projections for future changes in temperature and precipitation span a broad range, making it difficult to predict the future climate that forests will experience, particularly at the regional level. The ecological models used to relate forest distribution and productivity to changes in climate introduce additional uncertainty. Thus, current projections could fail to accurately predict the actual long-term impacts of climate change on the forestry sector.

The authors and the Pew Center gratefully acknowledge the input of Ralph J. Alig, Linda Joyce, G. Cornelis van Kooten, and William H. Schlesinger on this report. The Center would also like to thank Joel Smith of Stratus Consulting for his assistance in the management of this Environmental Impacts Series.

Executive Summary

Climate change is expected to have far-reaching consequences for forests and, subsequently, timber production in the United States. Although studies have shown that forests have adapted to temperature increases of 2-3°C (3.6-5.4°F) in the past, these changes occurred over thousands of years. Current climate predictions suggest that average global mean temperatures could rise 1.5-5.8°C (2.7-10.4°F) over this century alone. Such rapid changes in a relatively short period of time could affect forests significantly. Understanding how climate change will affect future forests and markets, however, is a complex task. Ecological and economic processes are exceptionally complicated, and understanding how integrated ecological and economic systems will respond to changing climate conditions remains a challenge. In spite of a number of remaining uncertainties, this report describes the many important insights into this process discovered over the last 10-20 years of research.

This report explores the potential effects of climate change on both natural and managed forest ecosystems, which differ significantly in their potential responses to climate change. Managed forests, such as forest plantations, receive significant amounts of human intervention in the form of planting, thinning and other management activities. These interventions have the potential to ameliorate the adverse effects of climate change. However, large areas of forest are considered natural and receive minimal direct human management, and thus may be more vulnerable to the effects of climate change. This duality within the forest sector makes it more difficult to state with precision what the overall economic impacts of climate change on forests will be. Further, the ecological changes caused by climate change could have large implications both for non-market attributes (e.g., biodiversity) and for other economic sectors associated with forests (e.g., recreation and water supply). The economic analysis in this report, however, focuses strictly on timber market impacts.

One of the most important ways that researchers discover clues about how forest ecosystems will respond to climate change is to explore the historical record for data regarding the impacts of past climate changes. This record indicates that individual tree species respond to warming either by changing their ranges or by increasing or decreasing their abundance. More recently, researchers have developed sophisticated models to explore how species distributions may change as climate changes. These changes could include increases or decreases in forest area, changes from one forest type to another, or movements of specific species from place to place.

In addition to species migration, it is important to consider how climate change could affect the productivity of forests (i.e., annual growth in forests). Existing studies show both positive and negative impacts on overall productivity, depending on the climate scenario. Further, some locations could experience higher productivity while others experience lower productivity. For example, forests in the southern United States are generally sensitive to the effects of drying, and productivity is more likely to decline there, while productivity is generally predicted to rise in the northern United States in response to low to moderate warming.

Understanding how productivity will change is complicated by an incomplete understanding of the effects of higher atmospheric carbon dioxide (CO2) concentrations on plant growth and ecosystem processes (so-called “carbon fertilization”). Experimental evidence suggests that carbon fertilization is likely to increase individual tree growth. Some evidence also suggests that the CO2 effect makes trees use water more efficiently, thereby making them less vulnerable to drought. Other evidence, however, suggests that the effects of carbon fertilization decline as trees age and at wider spatial scales where forest losses from other processes become important. Unfortunately, most measurements have been made on individual trees in experimental conditions, and not on entire forest ecosystems. In natural forests, and even in managed industrial forests, enhanced growth in trees could be offset by increased natural mortality elsewhere in the system. This is certainly the case for plantation forests where foresters usually predict increased thinning with higher growth in well-stocked stands.

While more precise regional estimates will be made as climate models provide a fuller understanding of regional climate change, and as ecological impacts become clearer, the existing results suggest that timber production could shift northward. Although some shifting will occur throughout most U.S. forests, the shifts would be strongest if the area suitable for southern softwoods expands northward. Hence, southern forests and markets appear most susceptible to climate change, in part because southern species are sensitive to drying effects, and in part because northward migration would erode the comparative advantage for timber production currently enjoyed by southern producers. Southern forests are also the most important economically since they account for well over one-half of U.S. production.

Changes in the frequency and intensity of disturbances like forest fires, pest infestations, and windthrow (i.e., from large storm events) are likely to have large consequences for the structure of both natural and managed forests. Natural forests, in particular, will be heavily influenced by changes in disturbances. Because disturbance has long been an important issue in forest management, managers have a number of tools available for adapting industrial and other managed forests as conditions change. Large-scale disturbances, however, can have substantial effects on markets. For example, although disturbances can cause substantial forest dieback, such ecological damages have the potential to cause short-term increases in timber supply, depressing timber prices for consumers.

As with agriculture, forest landowners have many options for adapting to the types of changes likely to occur with climate change, such as by salvaging dead and dying timber and by shifting to species that are more productive under the new climatic conditions. The long time lags between planting and harvesting trees, however, complicate the decisions for landowners. Adaptation can also occur at the market level, such as changing the types of species used in producing end products. End products are made from a wider variety of species today than 30 years ago; such adaptations help protect the market from large-scale changes in supply.

The following summarizes the current understanding of the potential impacts of climate change on U.S. forests and timber markets over the next century:

1. Tree species generally are expected to migrate northward or to higher altitudes in response to increased temperatures. While species will adapt over time by moving from one region to another, differential rates of change may cause significant differences in the types of natural stands in the future. Rates will depend critically on (a) how fast seeds migrate into new regions that are climatically suitable for a species after a climate change, (b) changes in the spread of insects and disease, (c) the spread of wildfire in different climates, and (d) human interventions to promote species migration.

2. Forest productivity is expected to change, but the changes could be positive or negative. Forests could become more or less productive, depending on how much climate changes (including both temperature and precipitation), how forests respond to higher carbon concentrations in the atmosphere, whether mortality changes, and whether disturbance-induced dieback increases or decreases. Many of these factors are expected to vary from region to region, suggesting that economic impacts are likely to differ among regions in the United States.

3. The effect of additional carbon dioxide in the atmosphere on forested ecosystems (“carbon fertilization”) is complex and uncertain, but it has large implications for understanding how forest productivity will change. Most studies suggest that forest area and productivity will increase if carbon fertilization enhances forest growth, but will decline if carbon fertilization does not occur. Plant-level experiments suggest that carbon fertilization will enhance tree growth, at least for some period of time. Scaling these results up to the ecosystem level is complex, but available studies suggest that carbon fertilization will be limited by competition, disturbance, and nutrient limitations. It is important to continue developing a better understanding of carbon fertilization effects, particularly at the ecosystem scale.

4. Changes in the frequency and severity of forest disturbance, such as storm damage, fires, and pests are likely to affect forest structure and function. The impact on markets, while generally negative, can be ameliorated by salvage. At the market level, salvage associated with disturbances can increase timber supply and reduce prices in the short-term, which benefits consumers. However, increased disturbance and lower prices generally have negative effects on landowners.

5. United States timber markets have low susceptibility to climate change because of the large stock of existing forests, technological change in the timber industry, and the ability to adapt. The United States currently consumes less timber than grows within the country each year, providing a cushion if climate change has short-term impacts on supply. Further, companies already substitute a wide array of species in end products, so that if particular species are negatively affected by climate change, markets can adapt by changing the types of species used in the production of end products. In addition, landowners can assist natural migration of timber by planting southern species in the North.

6. Economic studies have tended to find small negative to positive overall effects on timber production in the United States. While the studies have looked at a wide range of potential climate change effects across species within the United States, the net productivity effects used by the studies have tended to be positive over the long-term. Higher forest productivity translates into increased timber yield, increased timber inventory, increased supply, and lower prices. Lower prices generate overall net benefits, although they primarily benefit consumers at the expense of landowners. Lower forest productivity has the opposite effect.

7. Northern states may gain from climate change if productivity increases and if southern species move north, while southern states may lose production. Producers in southern regions are the most vulnerable to climate change because they have a large share of the nation’s current timber production capital, and the highly productive species in that region are sensitive to potential drying effects. Northern states are generally predicted to gain productivity and market share during climate change.

8. Understanding the economic effects of climate change on timber production is limited by scientific understanding of several key factors that control the response of natural and managed forests to climate change. Additional research is needed to enable ecologists and foresters to develop a more robust understanding of future changes in U.S. climate, ecosystem responses to climate change, the relationship between forest productivity and timber yield, and adaptation options available to foresters. Future clarification of these uncertainties will permit more informed assessments of the economic impacts of climate change to the forestry sector.

Conclusions

Unlike other sectors, such as agriculture, that are almost exclusively comprised of managed systems, forests are comprised of both natural and managed systems. This makes it more difficult to state with precision what the overall economic impacts of climate change on forests will be. Further, understanding the impacts on forests and timber markets is difficult given the long time lags between the planting and harvesting of trees.

Despite the many practical problems with understanding climate change impacts on forested ecosystems and timber markets, the combination of historical observation, modeling results, and experimental data allows us to draw several conclusions. Future research will certainly revise these conclusions, but the following points summarize the most important findings in the research to date regarding the overall impacts of climate change on forest ecosystems and timber markets over the next century:

1. Tree species generally are expected to migrate northward or to higher altitudes in response to increased temperatures. While species will adapt over time by moving from one region to another, differential rates of change may cause significant differences in the types of natural stands in the future. Rates will depend critically on (a) how fast seeds migrate into new regions that are climatically suitable for a species after a climate change, (b) changes in the spread of insects and disease, (c) the spread of wildfire in different climates, and (d) human interventions to promote species migration.

2. Forest productivity is expected to change, but the changes could be positive or negative. Forests could become more or less productive, depending on how much climate changes (including both temperature and precipitation), how forests respond to higher carbon concentrations in the atmosphere, whether mortality changes, and whether disturbance-induced dieback increases or decreases. Many of these factors are expected to vary from region to region, suggesting that economic impacts are likely to differ among regions in the United States.

3. The effect of additional carbon dioxide in the atmosphere on forested ecosystems (“carbon fertilization”) is complex and uncertain, but it has large implications for understanding how forest productivity will change. Most studies suggest that forest area and productivity will increase if carbon fertilization enhances forest growth, but will decline if carbon fertilization does not occur. Plant level experiments suggest that carbon fertilization will enhance tree growth, at least for some period of time. Scaling these results up to the ecosystem level is complex, but available studies suggest that carbon fertilization will be limited by competition, disturbance, and nutrient limitations. It is important to continue developing a better understanding of carbon fertilization effects, particularly at the ecosystem scale.

4. Changes in the frequency and severity of forest disturbance, such as storm damage, fires, and pests are likely to affect forest structure and function. The impact on markets, while generally negative, can be ameliorated by salvage. At the market level, salvage associated with disturbances can increase timber supply and reduce prices in the short term, which benefits consumers. However, increased disturbance and lower prices generally have negative effects on landowners.

5. United States timber markets have low susceptibility to climate change because of the large stock of existing forests, technological change in the timber industry, and the ability to adapt. The United States currently consumes less timber than grows within the country each year, providing a cushion if climate change has short-term impacts on supply. Further, companies already substitute a wide array of species in end products, so that if particular species are negatively affected by climate change, markets can adapt by changing the types of species used in the production of end products. In addition, landowners can assist natural migration of timber by planting southern species in the North.

6. Economic studies have tended to find small negative to positive overall effects on timber production in the United States. While the studies have looked at a wide range of potential climate change effects across species within the United States, the net productivity effects used by the studies have tended to be positive over the long-term. Higher forest productivity translates into increased timber yield, increased timber inventory, increased supply, and lower prices. Lower prices generate overall net benefits, although they primarily benefit consumers at the expense of landowners. Lower forest productivity has the opposite effect.

7. Northern states may gain from climate change if productivity increases and if southern species move North, while southern states may lose production. Producers in southern regions are the most vulnerable to climate change because they have a large share of the nation’s current timber production capital, and the highly productive species in that region are sensitive to potential drying effects. Northern states are generally predicted to gain productivity and market share during climate change.

8. Understanding the economic effects of climate change on timber production is limited by scientific understanding of several key factors that control the response of natural and managed forests to climate change. Additional research is needed to enable ecologists and foresters to develop a more robust understanding of future changes in U.S. climate, ecosystem responses to climate change, the relationship between forest productivity and timber yield, and adaptation options available to foresters. Future clarification of these uncertainties will permit more informed assessments of the economic impacts of climate change to the forestry sector.

About the Authors

Dr. Herman H. Shugart
University of Virginia

Herman H. Shugart is the W.W. Corcoran Professor of Environmental Sciences at the University of Virginia. Prior to joining the University of Virginia in his current capacity in 1984, he worked for 13 years in Tennessee – eventually as a Senior Research Scientist at Oak Ridge National Laboratory and as a Professor in Botany at the Graduate Program in Ecology at the University of Tennessee. Dr. Shugart has also served as a Visiting Fellow in the Australian National University (1978-1979, 1993-1994), in Australia’s Commonwealth Industrial and Scientific Research Organization, Division of Land Use Research (1982) and Division of Wildlife and Ecology (1993-1994), in the International Meteorological Institute at the University of Stockholm, Sweden (1984), and in the International Institute of Applied Systems Analysis, Laxenburg, Austria (1987,1989).

Dr. Shugart has served on the editorial board of several scholarly journals including Ecology, Ecological Monographs, Annual Reviews in Ecology and Systematics, Biological Conservation, Landscape Ecology, Journal of Vegetation Science, Forest Science, Global Change Biology, and The Australian Journal of Botany. He is the author of 300 publications including 12 books, 65 book chapters and 114 papers in peer-reviewed journals. A recent book, Terrestrial Ecosystems in Changing Environments was published in 1998 by Cambridge University Press, which reviews the ecological issues of predicting responses to global and regional climatic change. Recent honors include his election, as a foreign member, to the Russian Academy of Sciences in recognition of his work in Forest Ecology (2001); his designation as the 1999 Distinguished Alumnus from his alma mater, Department of Biological Sciences, University of Arkansas; and his identification as a Highly Cited author (top 1/2 percentile of scientific citations) in the area of Ecology/Environment by the Institute for Scientific Information.

Dr. Shugart received B.S. and M.S. degrees in Zoology at the University of Arkansas and received his Ph.D. (also in Zoology) from the University of Georgia in 1971.

Roger A. Sedjo
Resources for the Future

Dr. Sedjo is a Senior Fellow and the Director of the Forest Economics and Policy Program at Resources for the Future (RFF), a Washington based policy research organization, and the President of the Environmental Literacy Council (ELC), a nonprofit environmental education group. Dr. Sedjo has written extensively on forest and environmental issues, both domestic and international, having authored or edited fourteen books related to forestry, natural resources and the environment. His early work focused on timber supply and forest plantation issues, while more recent work is devoted more to the environmental aspects of forests.

Dr. Sedjo has served on a number of scientific panels and was a member of the Secretary of Agriculture’s Committee of Scientists, which made recommendations on Forest Service planning, and edited a recent book, A Vision for the US Forest Service (2000). He was a co-Chair of the chapter on “biological carbon sinks” in the Intergovernmental Panel on Climate Change’s (IPCC) Third Assessment Report (2001). He was also a contributor to two chapters in the IPCC’s Second Assessment Report (1995 ). Additionally, he has worked for the past several years with the Japanese Government in assessing their options toward meeting their carbon targets under the Kyoto Protocol. Recently, he has completed a study for the Department of Energy that resulted in the report, Estimating Carbon Supply Curves for Global Forests and Other Land Uses (with Brent Sohngen and Robert Mendelsohn). In addition, his recent papers on climate change have been featured in Bulletin of the Forestry and Forest Products Research Institute, Journal of Agricultural and Resources Economics, and Environment Science and Policy.

Dr. Sedjo has been a consultant to a wide array of organizations including the World Bank, the Global Environmental Facility, the Asian Development Bank, U.S. Agency for International Development, the OECD, Harvard Institute for International Development and others. Dr. Sedjo earned his B.A. and M.S. degrees at the University of Illinois, and a Ph.D. at the University of Washington (Seattle).

Dr. Brent L. Sohngen
The Ohio State University

Brent Sohngen is an associate professor in the Department of Agricultural, Environmental, and Development Economics at The Ohio State University. Prior to his appointment at Ohio State in 1996, he was a Gilbert White Postdoctoral Fellow at Resources For the Future in Washington, D.C.

His primary research interests lie in modeling land-use and land-cover change, examining impacts of climate change in the forestry sector, and the economics of nonpoint source pollution. Dr. Sohngen also leads an extension and outreach program in environmental and natural resource economics. The program focuses on linking research on natural resource and environmental economics to natural resource policy and management issues in the state of Ohio.

He obtained a bachelor’s degree from the Department of Agricultural Economics at Cornell University in 1991, and a doctorate from Yale University in 1996.

Brent Sohngen
Herman Shugart
Roger Sedjo
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Solutions FAQs

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What can the average individual do to help combat climate change? Can it be an individual effort, or is this really the responsibility of corporations and governments to resolve?

  • Participation by individuals is key to ultimately curbing global climate change.
  • The following are examples of effective, yet simple activities: reducing energy use at home by purchasing energy efficient home appliances; planting trees to absorb carbon from the atmosphere; walking or taking public transportation instead of driving; making smart consumer choices by purchasing environmentally sound products and energy-efficient vehicles; and practicing waste minimization, product reuse, and recycling.

How are we going to reduce carbon dioxide emissions with an increased consumer demand for power?

  • First, not all GHG emissions are CO2 emissions, and not all CO2 emissions are from power use. So you can reduce GHG emissions in other sectors like agriculture, forestry, and waste management without even addressing power. In addition, expanding the production of renewable energy and improving energy efficiency are ways to meet consumer demands for power without increasing CO2 emissions.

What are states doing to address climate change?

  • States have shown a great deal of interest in mitigating climate change. They have found that activities that reduce GHG emissions also have other benefits such as curbing pollution, reducing traffic, and generally improving the local quality of life.
  • States have conducted GHG inventories and initiated state action plans that identify and implement policies to reduce GHG emissions.
  • Other state initiative include providing loans and tax incentives to encourage energy efficiency, investing in carbon sequestration research and public transportation, establishing registries for businesses to report their GHG emissions reductions, and providing venues for trading emissions credits.
  • For more information on state action, visit our database of state case studies or read our report.

Over the past several years, how much has the development of clean coal technology reduced greenhouse gas emissions in the US? Do you see a real potential for its use?

  • Clean coal technology is a generic term for a set of technologies that reduce harmful emissions from coal burning. Some of these technologies reduce greenhouse gas emissions, but some only address other air pollutants, such as sulfur dioxide. Thus far clean coal technology has made a greater impact on these other pollutants, but there are promising technologies that would reduce GHG emissions from coal burning, or would capture and sequester CO2 emissions from coal burning. To the extent we continue to use coal, it is important to take advantage of these technologies.

What role, if any, can renewable energy play in CO2 reduction?

  • Renewable energy plays a small role now, but it is expected to play an increasingly important role over time. Wind and biomass energy are already cost-competitive with other forms of electric generation in some instances. Great technological strides have been made recently in hydrogen-powered fuel cells. There is enormous potential for solar energy and hydrogen to power our homes and cars in the future.
  • Several states have adopted renewable portfolio standards that require an increasing role for renewables as sources of electric power.

Because transportation accounts for a significant of greenhouse gas emissions internationally, how do you propose we reduce emissions in this sector? What do you think the technologies of the future may be?

  • Some technologies that will reduce emissions are already here, such as hybrid-electric vehicles like the Toyota Prius.
  • There have been exciting breakthroughs in hydrogen-powered fuel cells. Both fuel cells and biofuels are potential options for the future.
  • In the United States, it is likely that alternative and replacement fuels along with vehicle efficiency improvements will be the focus of a transportation emission mitigation strategy, rather than reducing driving. However, policies such as better traffic management, better urban design, and promotion of telecommuting might achieve multiple benefits, including GHG emission reductions.

    Report: Reducing Greenhouse Gas Emissions from U.S. Transportation
    In Brief: Taking Climate Change into Account in U.S. Transportation

Can we really live without fossil fuels, and what are the alternatives?

  • Yes, we can move away from fossil fuels, but not overnight. Our economy is currently dependent on fossil fuels, but it is not necessary that it remain dependent on them. Over time, with innovation, market incentives, and the right policies, we can transition to different fuels, different infrastructure, higher efficiency, and different technologies.
  • We need to concentrate on the development of alternative energy sources such as wind energy and solar power. Technological innovation in energy efficiency is also important.

How will workers be affected as climate change policies are implemented? And how can the adverse impacts be reduced?

  • While it is important to recognize that the costs of addressing climate change are likely to fall disproportionately on certain industries, communities, and workers, the design and implementation of effective government programs can greatly assist workers adversely affected by climate change policies.
  • Programs may include substantial retraining and education for laid-off workers, advance notice of layoffs when possible, substantial income support for program participants, and maintenance of laid-off workers' health and pension benefits until they find suitable employment.

    Report: Community Adjustment to Climate Change Policy
    Report: Worker Transition: Global Climate Change

Press Release: New Report: Climate Change Poses Challenges for U.S. Forestry

For Immediate Release: 
February 26, 2003

Contact:  Katie Mandes
(703) 516-0606

NEW REPORT: Climate Change Poses Challenges for U.S. Forestry


Washington, DC - One-third of U.S. lands are covered by forests, making forest ecosystems one of the nation's most prominent natural resources. In addition to their contribution to biodiversity, water quality, and recreation, forests also play a significant role in the U.S. economy, and forestry or forestry-related enterprises are the dominant industries in many U.S. communities. According to a new study by the Pew Center on Global Climate Change, the U.S. forestry sector will face a number of challenges in the next century due to the impacts of climate change.

The Pew Center report, Forests and Global Climate Change: Potential Impacts on U.S. Forest Resources, explores the challenges climate change will pose to forest ecosystems and related economic enterprises over the next century.

"Changes in forest productivity, the migration of tree species, and potential increases in wildfires and disease could cause substantial changes to U.S. forests," said Eileen Claussen, President of the Pew Center on Global Climate Change. "Moreover, these ecological impacts will have direct implications for our economy. The timber industry in the southern United States is particularly vulnerable."

The key conclusions of the report include:


Forest location, composition, and productivity will be altered by changes in temperature and precipitation. Climate change is virtually certain to drive the migration of tree species, resulting in changes in the geographic distribution of forest types and new combinations of species within forests. In addition, climate change is likely to alter forest productivity depending upon location, tree species, water availability, and the effects of carbon dioxide (CO2) fertilization.


Changes in forest disturbance regimes, such as fire or disease, could further affect the future of U.S. forests and the market for forest products. Increased temperatures could increase fire risk in areas that experience increased aridity, and climate change could promote the proliferation of diseases and pests that attack tree species.


U.S. economic impacts will vary regionally. Overall, economic studies indicate that the net impacts of climate change on the forestry sector will be small, ranging from slightly negative to positive impacts; however, gains and losses will not be distributed evenly throughout the United States. The Southeast, which is currently a dominant region for forestry, is likely to experience net losses, as tree species migrate northward and tree productivity declines. Meanwhile, the North is likely to benefit from tree migration and longer growing seasons.


As a managed resource, the implications of climate change for the forestry sector are largely dependent upon the actions taken to adapt to climate change. The United States currently has vast forest resources, and more timber grows within the United States than is consumed each year. If professional foresters take proactive measures, the sector may minimize the negative economic consequences of climate change.


A number of challenges currently limit our understanding of the effects of climate change on forestry. Existing projections for future changes in temperature and precipitation span a broad range making it difficult to predict the future climate that forests will experience, particularly at the regional level. Thus, current projections could fail to accurately predict the actual long-term impacts of climate change for the forestry sector.

Part of "Impacts" Series

Forests and Global Climate Change: Potential Impacts on U.S. Forest Resources, was prepared for the Pew Center by Herman Shugart (University of Virginia), Roger Sedjo (Resources for the Future), and Brent Sohngen (The Ohio State University). It is the ninth 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, climate change solutions, and the economics of climate change.

Click here for a complete copy of this report and previous Pew Center reports.

Climate Change: The Next 50 Years - One Decade at a Time

Climate Change:  The Next 50 Years - One Decade at a Time

Remarks of Eileen Claussen, President
Pew Center on Global Climate Change

SRI in the Rockies

October 18, 2002

Thank you very much and good morning. It is a pleasure to be here. I have to say that even the sound of SRI in the Rockies has an appealing ring to it. You can probably make just about anything sound better by adding those three little words: "In the Rockies." They're certainly more attractive than the three words I usually hear: "Inside the Beltway."

So I'd like to start by saying thank you to the conference organizers - not only for this wonderful setting, but also for the opportunity to speak with you about what I believe to be one of the most profound challenges of our time: the challenge of global climate change.

But I'd also like to say thank you to all of you. Because after many years of working to protect our environment, I've come to two very important realizations. First, you're better off working with the marketplace than against it. And second, positive change more often than not is the product of committed individuals who take the time to figure out what's right, and then act on it. Socially responsible investing blends those two realities into a very powerful force for change. And I can't tell you how pleased I am to be speaking to the SRI community about meeting the challenge of global warming. So again, thank you.

I'd like to cover a lot of ground today. I'll start with a quick overview of what science tells us about the risks and realities of global warming. Then I'll lay out in broad terms the challenge we face in the decades ahead if we are to avert the worst consequences of climate change. I'll highlight some of the efforts already underway to meet that challenge, both in government and in the business community. And finally, I'd like to talk about the critical role that all of you can and must play in getting more people and more companies to do the right and responsible thing.

So, as any informed discussion of climate change should, let's start with the science. In a word, it's compelling. There is overwhelming scientific consensus on three basic points: the earth is warming; this warming trend is likely to worsen; and human activity is largely to blame. Yes, you can find scientists who will argue otherwise. But these are the findings of the Intergovernmental Panel on Climate Change, which draws on the expertise of hundreds of climate scientists around the world. They are also the findings of a special, well-balanced panel put together by the National Academy of Sciences at the request of President Bush.

True, the earth's temperature has always fluctuated. But ordinarily these shifts occur over the course of centuries or millennia, not decades. The 1990s were the hottest decade of the entire millennium. The last five years were among the seven hottest on record. Scientists project that over the next century, the average global temperature will rise two to ten degrees Fahrenheit. A ten-degree increase would be the largest swing in global temperature since the end of the last ice age 12,000 years ago.

What are the likely consequences? We can expect rising sea levels, increased flooding and increased drought& more powerful storms, extended heat waves, and other types of extreme weather events. In some communities, global warming is no longer a theoretical matter. The impacts are being felt right now. Just ask the people of Alaska, where roads are crumbling and homes are sagging as the permafrost begins to melt.

Increasingly, we will all feel the impacts in our pocketbooks and our portfolios. Earlier this month, 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. This summer's wildfires here in the West and floods in central Europe are some of the latest examples. It's impossible to conclusively link any one of these disasters to the broader warming trend. But linked or not, these events give us a very real and very frightening preview of what's in store if the warming trend continues.

So what do we do about it? How do we protect ourselves, and future generations, from the rising risks of global warming? The short answer is that we must fundamentally transform the way we power our global economy. To keep our planet from overheating, we must dramatically reduce emissions of carbon dioxide and other greenhouse gases. The primary source of these gases is the combustion of fossil fuels. So our goal over time must be to steadily reduce our reliance on coal and oil and to develop new sources of energy - clean energy.

Clearly, this is a tall order. In fact, it will take nothing short of a new industrial revolution. Some revolutions happen overnight. This one will take time. It takes time to develop and adopt new technologies. It takes time to turn over our capital stock. But we can't afford to let this revolution take too long - every day, our emissions of greenhouse gases grow larger. So the first step in this revolution might be setting a goal - a long-term goal. Allow me to propose one. I propose that within 50 years we have in place all the technologies we need to power our economy without endangering our climate. I think it's a reasonable goal, one we can reach - provided we start right now and keep at it, one decade at a time.

This 50-year climate revolution must reach across each of the major energy-producing and -consuming sectors of our economy. In the electricity sector, we must burn coal more efficiently, increase our use of natural gas -- and ultimately move to renewables like solar and wind. In transportation, we can dramatically improve fuel economy right now, but at the same time should be switching to hybrid engines and developing alternatives like hydrogen fuel cell vehicles that will make the internal combustion engine obsolete. In the building sector, we need to take advantage of all the smart designs available right now to make our homes, offices and stores far more energy efficient. And in the industrial sector, we need to redesign the entire chain of commerce -- from inputs, to production processes, to product mixes, to the reuse and recycling of both waste and the products themselves.

All told, these changes imply technological and economic transformation on an unprecedented scale. How do we start? Here are some of the things we can do in decade one to get this revolution underway.

We can start by requiring companies to track and disclose their greenhouse gas emissions. We can assure companies taking steps now to reduce their emissions that their efforts will be recognized in any future regulatory system. We can raise efficiency standards. We can make strategic public investments in promising technologies. We can encourage farmers and foresters to adopt practices that take carbon from the atmosphere and store it in soil, crops and trees. We can step up efforts to determine whether we can safely and permanently sequester carbon in geologic formations deep underground. And we can begin building an economy-wide system that sets mandatory targets for reducing emissions and uses market approaches like emissions trading to meet them at the lowest possible cost.

So that's the challenge - revolutionize the way we power our economy in 50 years, one decade at a time. Is there any evidence that we're stepping up to the challenge? Not enough, I'm afraid, but perhaps more than you think.

Let's look first at the international picture. After a decade of negotiations, we are on the verge of establishing the first international constraints on greenhouse gas emissions. The European Union and Japan have ratified the Kyoto Protocol and if, as promised, Russia follows suit, the treaty will enter into force next year. Kyoto is only a start - its targets are far short of the emission reductions that ultimately will be needed, and it doesn't address developing countries, where much of the emissions growth in the coming decades will occur. But Kyoto is an important start. It lays a foundation and it reflects the determination of the international community to face up to this challenge.

The United States, of course, has chosen to stand outside this international effort. President Bush has rejected Kyoto and offered up instead a domestic strategy that relies exclusively on voluntary action. The President's strategy sets a goal of reducing greenhouse gas intensity 18 percent by 2012. That might sound good, but it allows actual emissions to keep on growing. It is essentially business as usual. It effectively writes off decade one.

But if you look past the administration - if you look at what's happening elsewhere in Washington and across the country - the picture is a bit more encouraging. And that's in part because a funny thing happened on the way to Kyoto. Just as the President's rejection helped save the Protocol by rallying other nations to its defense, it elevated the issue here at home as well - both in the press, and in the political arena.

In Congress, members of both parties are more eager than ever to demonstrate their interest in climate protection. Nearly twice as many climate change bills were introduced in Congress over the past year as in the previous four years combined. One of the major sticking points in the stalled negotiations over an energy bill is a set of bipartisan climate provisions that would force the administration to start taking the issue seriously.

And in an interesting bipartisan pairing, Senators Joe Lieberman and John McCain plan to introduce a bill this year setting a national cap on greenhouse gas emissions and allowing companies to buy and sell carbon credits. The bill is not likely to move anywhere fast, but it will help spark a long overdue debate on just how the United States will live up to its obligations as the world's largest emitter of greenhouse gases.

One thing that's interesting is that when you get outside Washington - when you're no longer inside the Beltway, that is - you find people moving right past debate to action. A growing number of states and communities are taking steps to cut their greenhouse gas emissions. At least 42 states have programs that, while not necessarily directed at climate change, are achieving real emission reductions. Texas and 13 other states require utilities to generate a share of their power from renewable sources. New York State's new energy plan sets a goal of reducing emissions 10 percent below 1990 levels by 2020. Some states are going beyond target-setting and establishing direct controls on carbon from power plants and - in the case of California - from cars and SUVs.

The message being sent by the states is that with or without Kyoto - and for that matter, with or without Washington - there is growing support in the United States for getting serious about climate change.

Increasingly, we are hearing the same message from the business community as well. Many companies are not waiting for government mandates - they're taking steps to reduce their emissions right now. At last count, we had identified more than 40 major companies that have publicly committed themselves to greenhouse gas reduction targets.

Let me share just a few examples. Alcoa is aiming to reduce its emissions 25 percent below 1990 levels by 2010. DuPont is aiming for a 65 percent reduction. Toyota, IBM, Intel, Johnson & Johnson& all have adopted targets for reducing emissions. Rohm and Haas, TransAlta, and BP have already achieved their targets and set new ones. BP, in fact, has cut emissions 10 percent below 1990 levels - eight years ahead of target - and now has pledged to keep them there at least until 2010.

The list of companies taking voluntary action keeps growing. Many are signing up with EPA's Climate Leaders program, which helps companies measure their emissions and begin to reduce them. Even Exxon-Mobil, a leading champion of the administration's business-as-usual strategy, recently ran ads touting its efforts to get a handle on its emissions.

These voluntary efforts are encouraging. They're to be commended. But they're not enough. The companies that are truly committed to tackling climate change know that we will never achieve the deep emission cuts we need unless everyone moves far enough, and fast enough, in the right direction. And that will happen only if the government requires it. That is why the companies we work with at the Pew Center recently called for the development of a comprehensive national climate strategy that is flexible and market-based but also has teeth - a strategy of mandatory, not voluntary, reductions.

And this leads me, finally, to your role in launching our 50-year climate revolution. I said earlier that I've learned it's better to work with the market than against it. In fact, I believe that ultimately only the market can mobilize the resources and the ingenuity needed to meet the challenge of climate change. The market, of course, will only deliver if there is a demand. That is why mandatory government policies are so critical. But the demand should not come from government alone. It should come from each of us as well - as consumers and as investors. And there, you are at the leading edge.

As socially responsible investors, you can help distinguish between the companies that are just painting themselves green, the companies that are actually cutting their emissions, and the companies that are going the next step and calling on government to mandate action by all. To do that, you need to need to know how a company is managing its carbon risk - what its emissions look like and what it's doing to reduce them. You need to know which companies are seizing the opportunities presented by climate change - which companies are looking ahead and investing now in the technologies we need in place 50 years from now. And you need to know which companies are pressing our elected leaders to do the right thing.

Increasingly, investors are demanding the information they need to make these assessments, and they're demanding corporate accountability on climate change. This year saw a record number of shareholder resolutions on climate change, and record support for them. Some drew votes of nearly 30 percent. In most cases, the resolutions were withdrawn when the companies agreed to enter into dialogue about their greenhouse gas emissions and their disclosure practices.

We talk a lot about the environment. But if you are a business, or an investor, or a fund manager, the environment within which you operate is the market. And the rules of the market will change. The climate, in essence, will stop being free. There will be a cost for emitting carbon. Those who understand that reality, and make the adjustment, will not only survive but thrive. Because in every change there is opportunity, and the rewards flow to those who seize them first. But those who ignore the realities and fail to adjust will pay the price.

You can help focus attention on these new realities - on both the risks and the opportunities. Keep impressing upon other investors, analysts, and companies themselves that climate change is a serious challenge that demands serious action. Tell them that if they want to be winners in the carbon-constrained world of the future, the time to start is now. Make sure CEOs understand that they ignore this issue at the peril of their companies and their shareholders -- not to mention, future generations.

Keep spreading the word because the market is both a harsh arbiter and the great mobilizer. And you are the market. 

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