Change Could Devastate U.S. Wetlands
Environmental News Service
DC, January 29, 2002 (ENS) - Global climate change
threatens the health of lakes, streams, rivers and wetlands
throughout the United States, finds a new report from
the Pew Center on Global Climate Change. The temperature
increases and variations in weather patterns projected
for the next 100 years will change the distribution of
freshwater fish and affect many other aquatic species,
the report argues.
"The United States' freshwater and wetland ecosystems face
multiple threats to their health and stability, including
changes in land use, environmental pollution, and the diversion
of water for drinking, irrigation, and other uses," said
Eileen Claussen, president of the Pew Center on Global Climate
Change. "To these threats we must now add the very real
and very serious effects of global climate change and its
potential to transform the essential character of our lakes,
rivers, streams and wetlands."
The Pew Center report, "Aquatic Ecosystems and Global
Climate Change: Potential Impacts on Inland Freshwater
and Coastal Wetland Ecosystems in the United States,"
draws on a variety of sources to summarize researchers'
current understanding of the potential impacts of climate
change on U.S. aquatic ecosystems.
Dr. Mark Brinson, a professor of biology at East Carolina
University and one of the report's authors, notes that
climate change will worsen the already major problems
facing wetlands from human activities like logging, development
and polluted runoff.
wetlands are absolutely essential for maintaining biodiversity
in the U.S.," Brinson said during a press conference releasing
the report. "There are species that occur there that occur
More than half the nation's historic wetlands have been
destroyed since colonial times, Brinson noted. Those that
remain have been degraded by pollution and changes such
as logging or dredging, he said.
Dr. N. Leroy Poff, an assistant professor of Biology at
Colorado State University, warned that climate change
could fundamentally alter the ecological processes of
aquatic ecosystems. For example, increased water temperatures
will make some streams, rivers and lakes too warm for
the fish and other creatures that now live there, said
Poff, a coauthor of the report.
Some animals may be able to move farther north to reach
cooler waters. But climate scientists project that to
reach waters of optimal temperature, some species might
need to move more than 400 miles (644 kilometers) farther
north - a prohibitive distance, Poff noted, considering
the natural and manmade barriers that lie along many waterways.
Dams and waterfalls may prevent fish and other creatures
from moving upstream in rivers that flow north and south.
Other rivers flow largely from east to west, making northward
movement impossible. Chemical barriers like pollution
can also trap migrating aquatic species.
Some species like trout, which live only at the pure, cold
headwaters of streams, may go extinct, Poff warned. In lakes,
large species may be lost as the level of dissolved oxygen
in the water falls due to rising temperatures.
Coauthor Dr. John Day, a professor of environmental sciences
at Louisiana State University, detailed the problems which
rising sea levels could pose for coastal wetlands and
estuarine systems, which he called "among the most highly
productive and diverse ecosystems on Earth."
A half meter (1.6 foot) rise in sea level brought on by
melting glaciers and ice caps - which many climate scientists
consider a likely result of a warming climate - would
inundate some 46,000 square miles (119,000 square kilometers)
of coastal wetlands, Day said. The repercussions could
include increased coastal flooding due to the loss of
buffering wetlands, and reductions in the populations
of game fish that depend on shallow wetlands as nursery
Rising global temperatures will cause the wetland areas
of Alaska and Canada to release additional carbon dioxide
and other greenhouse gases into the atmosphere, increasing
and accelerating the impacts of global warming, the authors
Among the other key conclusions of the report:
in water temperatures as a result of climate change
will alter the geographic distribution of aquatic plant
and animal species.
The severity of these impacts may be limited if species
can migrate to new areas as climate changes. However,
the ability of species to migrate may be compromised
by human activities that block migration corridors,
potentially causing reductions in biodiversity.
in precipitation will alter river and streamflows affecting
ecosystem productivity and reducing water quality.
Populations of aquatic organisms are sensitive to
the effects of floods, droughts and other extreme
weather events, which are likely to increase as a
result of climate change.
ecosystems have a limited ability to adapt to climate
Governments, communities, businesses and individual
citizens can take a number of steps to reduce the
likelihood of significant impacts to these systems
while improving their ability to adapt to climate
These actions, which the authors call climate insurance,
include: maintaining riparian forests; reducing pollution
from a variety of sources; restoring damaged ecosystems;
minimizing groundwater withdrawal; and strategically
placing new reservoirs to minimize their ecological
"Our rivers, lakes, streams, and wetlands support economically
important fisheries and provide Americans with clean drinking
water, water for irrigation, recreational opportunities,
and more," said Claussen. "This report shows that climate
change puts all of these services at risk, but it also shows
there are things we can do to reduce that risk."
Ecosystems and Global Climate Change" is the seventh in
a series of Pew Center reports examining the potential
impacts of climate change on the U.S. environment. Earlier
reports have focused on domestic and international policy
issues, climate change solutions, and the economics of
The report is available at: http://www.pewclimate.org