|
NEWS RELEASE
1/3/03
CONTACT: Klas Bergman,
Institute for International Studies: (650) 723-8490, kbergman@stanford.edu
Effects
of global warming already being felt on plants and
animals worldwide
Global
warming is having a significant impact on hundreds of
plant and animal species around the world -- although
the most dramatic effects may not be felt for
decades, according to a new study in the journal Nature.
"Birds
are laying eggs earlier than usual, plants are
flowering earlier and mammals are breaking
hibernation sooner," said Terry L. Root, a
senior fellow with Stanford's Institute for
International Studies (IIS) and lead author of the
Jan. 2 Nature study.
"Clearly,
if such ecological changes are now being detected
when the globe has warmed by an estimated average of
only 1 degree F (0.6 C) over the past 100 years, then
many more far-reaching effects on species and
ecosystems will probably occur by 2100, when
temperatures could increase as much as 11 F (6
C)," Root concluded.
Climatic
and biological changes
In their
Nature paper, Root and her colleagues analyzed
143 scientific studies involving a total of 1,473
species of animals and plants. Each study found a
direct correlation between global warming and
biological change somewhere in the world. For
example, several studies revealed that, as
temperatures increased in recent decades, certain
species began breeding and migrating earlier than
expected. Other studies found that the geographical
range of numerous species had shifted poleward or
moved to a higher elevation -- indicating that some
plants and animals are occupying areas that were
previously too cold for survival.
Were
these biological and behavioral changes isolated
events, or did they reflect a worldwide pattern
consistent with global warming? After exhaustive
statistical analyses of all 143 studies, Root and her
co-authors concluded that global warming is, in fact,
having a significant impact on animal and plant
populations around the world.
"Our
study shows that recent temperature change has
apparently already had a marked influence on many
species," they wrote, noting that a rapid
temperature rise in combination with other
environmental pressures "could easily disrupt
the connectedness among species" and possibly
lead to numerous extinctions.
Swallows,
geraniums and spruce
In their
analysis, Root and her co-workers revealed that
nearly 1,200 species -- roughly 81 percent of the
total number analyzed -- have undergone biological
changes that were "consistent with our
understanding of how temperature change influences
various traits of a variety of species and
populations from around the globe."
Their
overall analysis of studies involving temperate-zone
species revealed that springtime events -- such as
blooming, egg laying and the end of hibernation --
now occur about 5.1 days earlier per decade on
average.
The
North American tree swallow offers a good example.
Field biologists, who kept track of some 21,000 tree
swallow nests in the United States and Canada over
the last 40 years, concluded that the average
egg-laying date for female swallows has advanced by
nine days a phenomenon that mirrors other North
American studies confirming higher temperatures and
the earlier arrival of spring.
Similar
long-term observations of flowering plants in
Wisconsin revealed that wild geraniums, columbine and
other species are blooming earlier than before.
Studies in Colorado also showed that marmots are
ending their hibernations about three weeks sooner
than they were in the late 1970s.
Other
studies confirmed that a variety of species --
including butterflies and marine invertebrates --
have shifted their ranges northward as temperatures
increased. Measurements taken in Alaska revealed that
growth in white spruce trees has been significantly
stunted in recent years another expected
consequence of a rapidly warming climate, Root said.
"Climate
change models predict that the poles will warm more
quickly than the equator, so it's not surprising that
we're getting the strongest signals of biological
change from Alaska and other northern regions,"
she added.
Proactive
response
The
authors pointed out that, although plants and animals
have responded to climatic changes throughout their
evolutionary history, a primary concern for wild
species and their ecosystems is the rapid rate of
change predicted during the next century.
"The
problem will be the differential response of
species," Root explained. "I call it the
tearing apart of communities. For example, four types
of warblers feed on spruce budworm caterpillars. But
the birds are shifting north. What happens when the
birds no longer are present in the southern portion
of their ranges, and the caterpillar population is no
longer kept in check?"
She
predicted that rapid climate change, coupled with the
loss of habitat and other ecological stressors, could
lead to the disappearance of species -- a consequence
that might be avoided by taking proactive instead of
reactive conservation measures.
"For
example, there's a very high probability that global
warming could contribute to a 50 percent decline in
breeding waterfowl populations," Root noted.
"One thing we might do now is to consider
adjusting the bag limits for hunters so we don't add
insult to injury in the coming years. Because
anticipation of changes improves our capacity to
manage, it behooves us to increase our understanding
about the responses of plants and animals to a
changing climate."
Other
co-authors of the Nature study are Jeff T.
Price of the American Bird Conservancy in Colorado;
Kimberly R. Hall of Michigan State University;
Stephen H. Schneider, a professor of biological
sciences at Stanford and an IIS senior fellow;
Cynthia Rosenzweig of the NASA Goddard Institute for
Space Studies; and Alan Pounds of the Golden Toad
Laboratory for Conservation in Costa Rica. The study
was supported by the U.S. Environmental Protection
Agency, the Winslow Foundation and the University of
Michigan.
-30-
By Mark
Shwartz
|
