Global warming will negatively impact tropical species

Scientists have measured in laboratories how sensitive different species are to changes in temperature. For insects, the data is comprehensive and includes information on how temperature affects the population growth rate for species, Deutsch said. He and his colleagues — who included Joshua Tewksbury, assistant professor of biology at the University of Washington, and Raymond Huey, professor of biology at the University of Washington — studied the data, then went to climate models and analyzed what the predicted temperature change in various regions implied about species' future growth rate.

According to climate predictions, more rapid rates of warming of the Earth's surface will occur in the higher latitudes, especially in the polar regions, than at the equator, Deutsch said.

"You would think a larger warming in Alaska would have a greater impact on the organisms living there than a much smaller increase in, say, Panama or Costa Rica," he said. "We found the opposite will be true. A 1-degree temperature change in Panama will not be felt the same way by an organism as a 1-degree temperature change in Alaska."

The range of temperature tolerance that an organism has is largely dependent on how much temperature variability it experiences. In the tropics, the amount of temperature variability is very small; there is little difference between summer and winter, while in Alaska, the seasons are dramatically different.

To live in their environments, organisms in the tropics should have a relatively narrow tolerance for temperature change, while in the high latitudes, organisms should be able to tolerate a much wider variation in temperature.

"The magnitude of the impact of global warming depends largely on what we do to slow it down," Deutsch said.

Deutsch studies interactions between the Earth's climate and biological systems such as ecosystems. He is an expert in biogeochemistry, a new field that studies how biological, chemical and geological processes influence the chemical composition of the atmosphere and its climate.

The Proceedings of the National Academy of Sciences research is federally funded by the National Science Foundation, as well as by the University of Washington's Program on Climate Change, where Deutsch was a postdoctoral scholar and where he conducted the research.

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