From The San Francisco Gate, 1/8/04:
http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/01/08/MNGU045MCV1.DTL
Dire warming warning for Earth's species
25% could vanish by 2050 as planet heats up, study says
Jane Kay, Chronicle Environment Writer
Thursday, January 8, 2004
More than 1 million plant and animal species will vanish if global
temperatures continue to rise as predicted in the next 50 years,
scientists say in the first authoritative attempt to gauge the impact
of climate change on wildlife.
Even small fluctuations in climate can affect a species' ability to
remain in its original habitat and survive, according to a study
published Wednesday in the British journal Nature.
Authors estimate that about a quarter of the estimated 5 million or
more land species on the planet may lose habitat and face extinction
as they seek cooler temperatures to survive, either by moving to
higher ground or away from the equator and closer to the poles.
The key problem, said co-author Lee Hannah, a biologist at the Center
for Applied Biodiversity Science at Conservation International in
Washington, D.C., is that vulnerable species have no escape routes as
temperatures rise.
"Slight increases in temperature can force (a species) to move toward
its preferred, usually cooler, climate range. If development and
habitat destruction have already altered those habitats, the species
often have no safe haven,'' he said.
The researchers examined impacts on flora and fauna of three scenarios
of climate change between now and 2050, ranging from an average annual
temperature increase of about 1.4 to 3.6 degrees Fahrenheit.
The midrange prediction shows temperatures increasing by about 3
degrees.
Under that scenario, said lead author Chris Thomas, a biologist at the
University of Leeds (England), about 1.25 million species, or 24
percent of the terrestrial species of plants and animals, will be
extinct or on the way to extinction in 50 years.
Results were drawn from studies of 1,103 animal and plant species in
Mexico, Australia, Europe, the Amazon, the Brazilian Cerrado and South
Africa, representing 20 percent of the Earth's landmass.
Researchers estimated that 15 to 37 percent of those species could go
extinct or be on the path toward extinction by 2050, depending on
which of the three climate assumptions is used.
The researchers extrapolated the results to make global estimates.
Computer models used to complete the analysis took into account the
ability of different species to move under pressure and the current
state of their habitat.
Some findings are as follows:
-- Using the most conservative estimate of global temperature
increases, 18 percent of species would be lost or "committed to
eventual extinction.'' In the dry forest of the Brazilian Cerrado, 66
percent of the plants would be facing extinction.
-- Under the midrange prediction, 24 percent of species would be lost.
Nearly 70 percent of mammals in South Africa that cannot readily move
to alternative sites would vanish.
-- With a rise of more than 3.6 degrees, 35 percent of species would
be lost. In Queensland, Australia, 85 percent of birds would face
extinction. In the Amazon, 87 percent of the plants would vanish.
Researchers from 14 institutions around the world cooperated on the
study.
It began a year ago, when scientists at Leeds, the Royal Society for
the Protection of Birds in Bedfordshire, England, and the National
Institute of Public Health and Environment in the Netherlands, among
others, realized that separate modeling efforts were under way in six
regions to discover how global warming might affect species.
In Queensland, the Boyd's forest dragon would have no choice but to
move upslope to find its preferred climate.
But because the lizard already is found only near mountaintops, it
would have nowhere to go.
In South Africa, the toffeeapple conebush, which bears a fruit that
looks like a candy apple, is already diminishing from drought and
warmer temperatures.
In Europe, the Scottish crossbill, a rare bird, would have to move to
Iceland to find a favorable climate, while the red kite, already
heavily threatened by hunting and habitat loss, would lose even more
territory.
The Oaxacan swallowtail, one of Mexico's rarest butterflies, which was
just discovered in 1975 in the Juarez Mountains, could no longer use
the natural habitat protected for it under law.
Despite the uncertainties of the modeling, the study authors said, "We
believe that the consistent overall conclusions across analyses
establish that anthropogenic (human caused) climate warming at least
ranks alongside other recognized threats to global biodiversity.''
In many regions, global warming will be the greatest threat, the study
said.
The authors recommended an immediate reduction of carbon dioxide and
other greenhouse gases, which are believed to be the prime cause of
global warming.
They also advise that conservation measures must be taken to help
prepare for the movement by species to survive.
The new study is the latest of several recent reports on global
warming, nearly all suggesting a growing consensus that humans are
affecting the climate in ways likely to have some devastating impacts
on the environment, such as more extreme weather events, earlier
spring thaws and flooding along coastlines.
Last month, two top U.S. climate researchers released a report that
brings near-unanimous agreement that the warming is caused by
combustion of fossil fuels and other industrial emissions.
They estimate a 90 percent chance that the world's climate will heat
up between 3.1 and 8.9 degrees Fahrenheit by the end of this century.
Predicted are more heat waves and droughts in some regions and heavy
precipitation in others.
Wildfires, vegetation changes and continuing melting of glaciers,
causing flooding and island inundation are forecast.
President Bush has decided not to sign the Kyoto treaty, an
international agreement setting deadlines for reducing greenhouse gas
emissions.
The administration's chief meteorologist, James Mahoney, assistant
secretary of commerce, said last month that he believed that natural
variation played as much a part in warming as human-caused activities.
He cautioned against dire scenarios based on many differing
atmospheric models.
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Harry
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