Embargoed until 2 p.m. EST
NSF PR 02-23 - April 10, 2002
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Researchers Project Future Shrinking Biodiversity
of Mexican Species
The effect of Earth's changing climate -- due to warming
from so-called greenhouse gases and other factors
-- on natural ecosystems may be felt by species most
at risk for reduced range or even extinction. A team
of researchers supported by the National Science Foundation
(NSF) and affiliated with the University of Kansas
Natural History Museum and other institutions has
reported on the first analysis of the potential impacts
of climate change on species in an entire country,
Mexico. The team's paper is published in this week's
Nature.
"This research predicts that global climate change
will cause substantial changes in the distribution
of Mexican bird, mammal, and butterfly species," says
Carol Johnston, program director in NSF's division
of environmental biology, which funded the research.
The research, led by Townsend Peterson of the University
of Kansas Natural History Museum, found that the changing
climate is predicted to bring about great instability.
"In some local communities more than 40 percent of
species are expected to turn over, which will lead
to a cascade of further effects," said Peterson, lead
author of the Nature paper. "If you remove enough
species from an ecosystem, it's like the old child's
game of pick-up-sticks -- there are only so many changes
you can make before the ecosystem just collapses on
you."
"This research marks a major step forward in being
able to investigate in a quantitative way the initial
impacts of climate change on ecosystems and biodiversity,"
said Peterson. "This is important because the modifications
affecting our climate are like a big experiment the
whole world is doing without knowing what's going
to happen."
For example, the west Mexican chachalaca, a bird found
only in tropical southwestern Mexico, may be greatly
affected by changing climate. Under some climate change
scenarios, the species' distribution area in interior
Mexico would become much less habitable, while its
coastal range would remain intact. A narrow band of
habitat in the foothills of the coastal mountain ranges
might become more habitable.
The Nature article outlines research that not
only looks at a great many species across a whole
community but also examines them one-by-one, using
realistic assumptions about their ability to change
where they live in response to climate change. "That
species-by-species look has allowed us to appreciate
just how big the differences are in the way each species
can respond to climate change," said Peterson.
"What we found is that the impacts aren't uniform,
and the strongest effects turned out to be in the
central Chihuahuan desert, south of New Mexico," he
said. In that desert area, the researchers expect
the greatest species turnover and disruption of ecosystems,
which will unleash a complex chain of consequences
that are difficult to foresee in detail but will be
highly disruptive to ecosystems and certain species
in particular.
Previous research has looked in a broad-brush way at
how climate change would affect an ecosystem. For
example, if a warmer climate will cause a given habitat
to move northward, researchers made the assumption
that the various species would simply move along with
the ecosystem. Other detailed studies have been limited
to looking at only a few species. "What's unique about
what we've done is that for the first time we were
able to look at a whole community in detail," said
Peterson. His colleagues are affiliated with the Universidad
Nacional Autonoma de Mexico and the San Diego Supercomputer
Center.
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