Ecologists' Statement on the
Consequences of Rapid Climatic Change
May 20, 1997
President Bill Clinton
1600 Pennsylvania Ave.
Washington, D.C. 20500
Dear President Clinton:
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 Peņa
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)
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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