Animals Struggling To
Cope With Climate Change
Warmth
By Randolph E. Schmid,
AP Science Writer
WASHINGTON - If
you can't stand global
warming, get out of the
tropics.
While the most
significant harm from
climate change so far
has been in the polar
regions, tropical plants
and animals may face an
even greater threat, say
scientists who studied
conditions in Costa
Rica.
"Many lowland tropical
species could be in
trouble," the team of
researchers, led by
Robert K. Colwell of the
University of
Connecticut, warns in
Friday's edition of the
journal Science.
"The tropics, in the
popular view, are
already hot, so how
could global warming
harm tropical species?
We hope to put this
concern on the
conservation agenda,"
Colwell said.
That's because some
tropical species,
insects are an example,
are living near their
maximum temperatures
already and warmer
conditions could cause
them to decline, Colwell
explained.
"We chose the word
'attrition' to emphasize
slow deterioration," he
said. "How soon that
will be evident enough
for a consensus is
difficult to say."
But the researchers
estimated that a
temperature increase of
5.8 degrees over a
century would make 53%
of the 1,902 lowland
tropical species they
studied subject to
attrition.
That doesn't mean
today's jungles will one
day be barren, however.
"'Tis an ill wind that
blows nobody any good.
Some species will
thrive," Colwell said.
"But they are likely to
be those already adapted
to stressful
conditions," such as
weeds.
What of the others?
There are few nearby
cooler locations for
tropical plants and
animals fleeing rising
temperatures.
In the tropics in
particular, going up
rather than out may be
an answer.
That's because tropical
species with small
ranges would have to
shift thousands of
kilometers north or
south to maintain their
current climatic
conditions. "Instead,"
Colwell said, "the most
likely escape route in
the tropics is to follow
temperature zone shifts
upward in elevation on
tropical mountainsides."
For example, moving
uphill, the researchers
said, temperature
declines between 9.4 and
11.7 degrees for every
3,280 feet. To get a
similar reduction moving
north or south, species
would have to travel
more than 620 miles.
Of course moving won't
work for everyone;
species already living
on mountaintops will
have no place to climb.
The study provides an
important illustration
of the potential risk to
tropical species from
global warming,
Jens-Christian Svenning
of the University of
Aarhus, Denmark, and
Richard Condit of the
Smithsonian Tropical
Research Center note in
a commentary on the
findings.
"These numbers suggest
large risks," but are
likely to be
controversial because
there remain large gaps
in the knowledge of
species' sensitivity to
climate change, added
Condit and Svenning, who
were not part of the
research team.
Meanwhile, a separate
paper in Science reports
that warming climate has
already scrambled the
ranges of small mammals
in Yosemite National
Park.
Ranges for some
high-elevation mammals
such as the alpine
chipmunk have shrunk,
while animals living at
low elevations, such as
the harvest mouse, have
expanded their ranges
into higher reaches,
Craig Moritz of the
University of
California, Berkeley,
and colleagues report.
Earlier this year a
study of 171 forest
species in Western
Europe showed most of
them are shifting their
favored locations to
higher, cooler spots.
For the first time,
research can show the
"fingerprints of climate
change" in the
distribution of plants
by altitude, and not
only in sensitive
ecosystems, said
Jonathan Lenoir of
AgroParisTech in Nancy,
France.
His team found "a
significant upward shift
of species optimum
elevation, the altitude
where species are the
most likely to be found
over their whole
elevation range." |
