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Ecologists' Statement on the Consequences of Rapid Climatic Change -- May 20, 1997

CONTACT: Janet Basu, News Service (415) 723-7582; e-mail basu@stanford.edu

Ecologists warn President Clinton: Rapid climate change due to global warming could ruin ecosystems that society depends on Twenty-one of the nation's leading experts on ecological systems and climate, including four Stanford faculty members, sent a letter <<on Tuesday, May 20>> to President Clinton urging him to take a "prudent course" in upcoming global climate change negotiations. The scientists warn that the problem is not so much that the climate may get warmer over the next century, but that the changes could be so rapid that plants, animals and other species will be unable to adapt.

They warn that the resulting breakdown of ecosystems could lead to disturbances with major effects on human populations: fires, floods, droughts, storms, erosion and outbreaks of pests and pathogens, plus losses in fresh water, soil, forests, fisheries and other resources that human society depends on.

"The accompanying letter to President Clinton comes from a group of ecologists from around the country who have studied the potential impacts of global change on biotic systems. The signers include the leading international experts on many particular dimensions of this problem," said Harold Mooney, Stanford professor of biological sciences and the organizer of the effort. "As you will read in the letter, they all have deep concerns about the ecological consequences of rapid climatic change."

Among the signers are Mooney and Paul Ehrlich of Stanford, considered to be among the deans of international ecological research; Jane Lubchenco of Oregon State University, past president of the nation's premiere scientific society, the American Association for the Advancement of Science; the directors of major ecological research programs at the nation's top universities; and climate impact experts including Stephen H. Schneider of Stanford and David Schimel of the University Center for Atmospheric Research in Boulder, Colo. Seven are members of the National Academy of Sciences and five are past presidents of the Ecological Society of America.

(A complete list is printed below)

The letter is being sent as the Clinton Administration prepares instructions to the State Department for international negotiations on ways to reduce greenhouse gas emissions and other activities that contribute to global warming. The United States.and other countries are developing a protocol to strengthen the U.N. Framework Convention on Climate Change, and are expected to approve that protocol at a climate summit in Kyoto, Japan, in December.

Copies of the letter were sent to Vice President Al Gore, Secretary of State Madeleine Albright and State Department Under Secretary Timothy Wirth; Agriculture Secretary Dan Glickman, Energy Secretary Federico Peña; Interior Secretary Bruce Babbit; Carol Browner, administrator of the Environmental Protection Agency, and James Baker, administrator of the National Oceanic and Atmospheric Administration.

It will not be enough to set a distant date to stabilize greenhouse gases, as some policy makers have advised, the ecologists warn. If current levels of greenhouse gas emissions continue to rise, they are projected to lead to a rate of climate change significantly faster than at any time during the past 10,000 years.

The scientists call for a "prudent course" that would "limit climate change to the lowest rates feasible, given emissions that have already occurred." That would slow global warming to no more than 1 degree per century, according to a 1995 report by the Intergovernmental Panel on Climate Change (IPPC). But if humans continue to add carbon dioxide and other gases, the IPPC projects an increase of 2 degrees to 6 degrees Fahrenheit over the next hundred years -- with correspondingly greater changes at higher latitudes, including much of the United States.

The scientists said there is little data about the effects of such a rapid change - nothing on this scale has occurred in Earth's recent history. But they said scientists do know that climate change requires many species to shift their ranges for food and shelter. In today's world, pollution, disturbance of habitats and other human alterations of the landscape give many species less room to make those moves. In many cases, damage from pollution and human encroachment already have left important ecosystems less resilient and able to adapt to change.

In the United States, the scientists said, rapid climate change could mean the widespread death of trees, followed by wildfires and a replacement of forests by grasslands. National parks and forests could become inhospitable to the rare plants and animals that are preserved there - and where the parks are close to developed or agricultural land, the species themselves may disappear for lack of another safe haven. Worldwide, fast-rising sea levels would inundate the marshes and mangrove forests that protect coastlines from erosion and serve as filters for pollutants and nurseries for ocean fisheries. "The more rapid the rate [of change] the more vulnerable to damage ecosystems will be," the scientists told the president. "We are performing a global experiment [with] little information to guide us."


May 20, 1997

President Bill Clinton 1600 Pennsylvania Ave. Washington, D.C. 20500

Dear President Clinton:

Ecologists' Statement on the Consequences of Rapid Climatic Change

Climate change driven by emissions of greenhouse gases is projected to occur at a very rapid rate, significantly faster, on a sustained global basis, than rates of climatic change during the past 10,000 years (1). Rapid climate change coupled with pollution, habitat fragmentation and habitat loss may lead to the decline and disappearance of many plant and animal communities that might otherwise survive a future climate that is relatively stable but warmer.

We believe that this situation constitutes a dangerous anthropogenic interference with the climate system, one that may not "allow ecosystems to adapt naturally to climate change" as is called for in the Framework Convention on Climate Change (1992). Accordingly, we believe that the prudent course would be to limit climate change to the lowest rates feasible given emissions that have already occurred. These correspond to global rates of warming of no more than 1 degree C per century.

Much of the current debate over limiting global climate change has focused on targets for stabilization of greenhouse gas concentrations many decades in the future. However from an ecological standpoint, it is the rapid rate as well as the total magnitude of climate change projected to occur that is pertinent to the future well-being of plant and animal communities and to the continuous availability of goods and services they provide to our society. Global mean temperature could increase by as much as 1-3.5 degrees C (2-6 degrees F), over the next 100 years. At higher latitudes, which include large portions of the United States, temperature increases could be much greater.

Rapid climate change is more dangerous to plant and animal communities than gradual climate change even if the total amount of change that eventually occurs is exactly the same.

During rapid climate change, disturbances like fires, floods, erosion, droughts, storms, pests and pathogen outbreaks may increase with adverse effects on ecosystem functions as important as water supply, soil fertility and carbon sequestration. After disturbance, aggressive, 'weedy' species, including exotics that outcompete native vegetation, may come to dominate these areas. In some US temperate forests, rapid climate change could lead to widespread tree mortality, wildfires and replacement of the forests by grasslands. Species that are long-lived, rare, or endangered will be severely disadvantaged.

In an increasingly developed world, there are fewer and fewer areas available in which native trees and plants can grow. Cities, highways, agricultural fields and other human activities limit available habitat and create barriers to the migration of plants and animals. In fact, many natural areas now can be considered 'islands' in a sea of developed land. Protected areas like national parks and forests were established with current climates in mind. Rapid climate shifts may reduce appropriate native habitats within protected areas while development outside the boundaries of the protected areas would make much of the neighboring new habitat unavailable and limit corridors for species to migrate to suitable new habitats. It would be difficult to imagine, for example, how the imperiled species of Everglades National Park, such as the Cape Sable Sparrow and American Crocodile, could migrate north into the urban and agricultural landscapes of coastal and central Florida and successfully re-establish themselves. Overall, climate change, in combination with existing anthropogenic habitat disruption and loss, could lead to steep declines in worldwide biodiversity.

Furthermore, conditions for plant and animal communities are considerably less hospitable now than prior to the industrial revolution. In many cases, plant and animal populations are less healthy and ecosystems less resilient to further disturbance due to environmental stress from human-made pollutants and habitat degradation. These stresses may reduce significantly an individual's or ecosystem's ability to cope successfully with climate change.

Climate change may also result in rapid sea level rise. Rapid sea level rise causes beach erosion and threatens coastal marshes and mangrove forests. While many of these coastal natural areas have kept pace with historic rates of sea level rise, faster rates may lead to inundation of marshes and mangroves more rapidly than new wetlands can form. Onshore human development will further hamper new establishment of coastal natural areas. Loss of habitat for a substantial number of species of birds, fish, shellfish, microorganisms and animals could result. Marshes and mangroves also protect shorelines from storms and high tides and act as filters for pollutants such as sewage and other effluents. Their loss would lead to increased erosion and degradation of onshore human development.

It is difficult to quantify precisely the response of a particular species or group of species to climate change. Because there are only sparse records of this type of rapid climate change available, we have little to guide our estimations. Scientists do know the following. Climate determines the distributions of many species. Significant climate change has in the past and will in the future require many species to shift their ranges. Species vary in their ability and opportunities to adapt or migrate. The rate of projected change is enough to threaten seriously the survival of many species. Pollution and human alteration of the landscape have reduced considerably the ability of plant and animal communities to adjust to rapid climate change. Ecosystems will experience a rate of sustained climate change that is unusually rapid and, for many areas, unprecedented during the past 10,000 years. The more rapid that rate, the more vulnerable to damage ecosystems will be.

We are performing a global experiment on our natural ecosystems for which we have little information to guide us. While plant and animal communities may be able to eventually adapt to a stable climate system that is warmer than the existing one, many species may not be able to survive a rapid transition to that new climate. The prudent course would be to limit climate change to the lowest rates feasible given current atmospheric accumulations of greenhouse gases. These correspond to global rates of warming of no more than 1 degree C per century.

(1) Climate Change 1995 - Impacts, Adaptations and Mitigation of Climate Change: Scientific-Technical Analyses. Contribution of Working Group II to the Second Assessment Report of the Intergovernmental Panel on Climate Change. Editors R.T. Watson, M.C. Zinyowera, R.H. Moss. Cambridge University Press, p. 21.

cc: Vice President Al Gore

Secretary Madeleine Korbel Albright
Department of State

Under Secretary Timothy E. Wirth
Department of State

Secretary Dan Glickman
Department of Agriculture

Secretary Federico Peña
Department of Energy

Secretary Bruce Babbit
Department of the Interior

Ms. Carol M. Browner,
Administrator United States Environmental Protection Agency (EPA)

Dr. D. James Baker,
Administrator National Oceanic and Atmospheric Administration (NOAA)

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Signatories of Ecologists' Statement

Dr. Fakhri Bazzaz
H.H. Timken Professor of Science Biological Laboratories 16 Divinity Ave. Harvard University Cambridge, MA 02138

Dr. Janine Bloomfield
Environmental Defense Fund 257 Park Ave. S New York, NY 10010

Dr. F. S. Chapin, III
Department of Integrative Biology University of California Berkeley, CA 94720

Dr. James Clark
Department of Botany & Division of Earth Sciences and Quaternary Ecology and Earth Surface Transformations Duke University Durham, NC 27708

Dr. Margaret B. Davis*,#
Department of Ecology, Evolution and Behavior University of Minnesota 1987 Upper Buford Circle St. Paul, MN 55108

Dr. Paul Ehrlich*
Bing Professor of Population Studies and Professor of Biological Sciences Stanford University Stanford, CA 94305

Dr. Christopher Field
Department of Plant Biology Carnegie Institution of Washington 290 Panama Street Stanford, CA 94305

Dr. Jerry F. Franklin#
Professor of Ecosystem Analysis College of Forest Resources University of Washington Seattle, WA 98195

Dr. Diana Wall Freckman
Director and Professor Natural Resource Ecology Laboratory, Associate Dean, College of Natural Resources Colorado State University Fort Collins, CO 80523

Dr. Gene Likens*,#
Director and President, Institute of Ecosystem Studies P.O. Box AB Millbrook, NY 12545

Dr. Jane Lubchenco*,#
Distinguished Professor and Wayne and Gladys Valley Professor of Marine Biology, Department of Zoology Oregon State University Corvallis, OR 97331-2914

Dr. Pamela A. Matson*
Soil Science Department Hilgard Hall, Room 108 University of California Berkeley, CA 94720

Dr. Harold Mooney*,#
Paul S. Achilles Professor of Environmental Biology Department of Biological Sciences Stanford University Stanford, CA 94305

Dr. Louis F. Pitelka,
Director Appalachian Environmental Laboratory Center for Environmental & Estuarine Studies Gunter Hall Frostburg, MD 21532

Dr. David S. Schimel
University Center for Atmospheric Research Climate System Modeling Program Boulder, CO 80307

William H. Schlesinger
James B. Duke Professor Department of Botany Duke University Durham, NC 27708-0340

Dr. Steve Schneider
Department of Biological Sciences Stanford University Stanford, CA 94305

Dr. Herman H. Shugart
W.W. Corcoran Professor and Director of the Global Environmental Change Program Department of Environmental Sciences University of Virginia Charlottesville, VA 22901

Dr. Boyd Strain
Professor of Botany Duke University Durham, NC 27708-0340

Dr. G. David Tilman
Distinguished McKnight University Professor and Director, Cedar Creek Natural History Area, University of Minnesota St. Paul, MN 55108

Dr. Peter Vitousek*
Clifford G. Morrison Professor in Population and Resource Studies Department of Biological Sciences Stanford University Stanford, CA 94305

*, Member, National Academy of Sciences #, Past President, Ecological Society of America

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Janet Basu, Science Writer, Stanford University News Service Press Building, Santa Teresa St., Stanford, CA 94305-2245 basu@stanford.edu phone 415-723-7582 <fax 725-9723>