Tropical insects risk extinction with global warming: study
Pastor Dale Morgan
Tropical insects risk extinction with global warming: study*
WASHINGTON, May 5 (AFP) May 05, 2008
Global warming could pose a greater risk to tropical insects and other
species sensitive to the slightest shifts in temperature than to
creatures living in the world's tundra, US scientists warned Monday.
While cold weather animals are used to huge temperature changes,
tropical species live under a much smaller temperature range and face a
bigger risk of extinction with an increase of just two or four degrees
Celsius, according to a team led by University of Washington scientists.
"In the tropics many species appear to be living at or near their
thermal optimum, a temperature that lets them thrive," said Joshua
Tewksbury, an assistant professor of biology at the Seattle, Washington
university.
"But once temperature gets above the thermal optimum, fitness levels
most likely decline quickly and there may not be much they can do about
it," he said.
For their research, published in the May 6 edition of the Proceedings of
the National Academy of Sciences, the scientists examined daily and
monthly global temperatures from 1950 to 2000.
They added climate model projections for warming in the first years of
the 21st century drawn up by a United Nations group of international
scientists, the Intergovernmental Panel on Climate Change.
The university researchers then compared the information with data
describing the link between temperature and fitness for 38 temperate and
tropical insects as well as cold-blooded animals such as frogs, lizards
and turtles.
While polar bears can develop thicker fur to shield them from freezing
temperatures, tropical species must use other tactics to protect
themselves from higher temperatures such as staying out of direct
sunlight or burrowing into the soil.
But hiding from the sun could prove useless to tropical animals already
living so close to their temperature comfort zone as the warmer weather
could come too fast for their physiologies to adapt, the scientists said.
"Many tropical species can only tolerate a narrow range of temperatures
because the climate they experience is pretty constant throughout the
year," said Curtis Deutsch, an assistant professor of atmospheric and
oceanic sciences at the University of California, Los Angeles.
"Our calculations show that they will be harmed by rising temperatures
more than would species in cold climates," he said.
"Unfortunately, the tropics also hold the large majority of species on
the planet," said Deutsch, a co-author of the study who was a University
of Washington postdoctoral researcher in oceanography.