March
27, 2007
A new
climate modeling study forecasts the complete disappearance of
several existing climates in tropical highlands and regions near
the poles, while large swaths of the tropics and subtropics may
develop new climates unlike any seen today.
In general,
the models show that existing climate zones will shift toward
higher latitudes and higher elevations, squeezing out the
climates at the extremes--tropical mountaintops and the
poles--and leaving room for unfamiliar climes and new ecological
niches around the equator.
The work,
by researchers at the University of Wisconsin-Madison and the
University of Wyoming, appears online in the journal Proceedings
of the National Academy of Sciences (PNAS) during the week of
March 26. The National Science Foundation (NSF) funded the
research.
The most
severely affected parts of the world span both heavily populated
regions, including the southeastern United States, southeastern
Asia, and parts of Africa, and known hotspots of biodiversity,
such as the Amazonian rainforest and African and South American
mountain ranges.
The
patterns of change foreshadow significant impacts on ecosystems
and conservation. "There is a close correspondence between
disappearing climates and areas of biodiversity," says
University of Wisconsin at Madison geographer Jack Williams,
primary author of the paper, which could increase risk of
extinction in the affected areas.
For
example, the Andes, Central America, South Africa and the
Indonesian Archipelago are all hotspots of biological diversity.
The projected disappearance of the climates unique to these
regions places some species at risk of extinction.
"As this
research shows, studies integrating paleoclimate data,
mathematical modeling and ecological principles provide insights
into climate cause-and-effect that are of great practical
consequence," says David Verardo, program director for
paleoclimate at NSF,
Williams and his
colleagues foresee the appearance of novel climate zones on up
to 39 percent of the world's land surface area by 2100, if
current rates of carbon dioxide and other greenhouse gas
emissions continue, and the global disappearance of up to 48
percent of current land climates.
The underlying effect is
clear, Williams says. "More carbon dioxide in the air means more
risk of entirely new climates or climates disappearing."
In an effort to keep up
with climate change, plant and animal species already have begun
to move away from the equator and toward the colder climates of
the poles. In mountain ecosystems, many lower-mountain species
are moving higher--to cooler spots. What will happen when they
"run out of room" on a mountainside?
The question becomes not
just whether a given climate will still exist, but "will a
species be able to keep up with its climatic zone?" Williams
says.
The work
was conducted in collaboration with Stephen Jackson at the
University of Wyoming and John Kutzbach at the University of
Wisconsin.
-NSF-
In the
highlighted paragraphs, above, the NSF researcher indicates that
already there is evidence of plant and animal species are
beginning to move toward cooler climates. Therein is the
implication that the regions at the equator are getting hotter.
