Warming Hits Tropical Creatures Harder

May 6, 2008 -- Global warming could pose a greater risk to tropical insects and other tropical species sensitive to the slightest shifts in temperature than to creatures living in the world's tundra, scientists warned.

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.