Biggest impact of warming is on life in the tropics

New research shows that even though the temperature increase has been smaller in the tropics, the impact of warming on life could be much greater there than in colder climates.

Researchers at the University of Wyoming used nearly 500 million temperature readings from more than 3,000 stations around the world to chart temperature increases from 1961 through 2009, then examined the effect of those increases on metabolism.

If an organism has to spend more time eating or conserving energy, it might have less time and energy for reproduction, said Raymond Huey, a University of Washington biology professor.

Using an understanding that metabolic rates for cold-blooded animals increase faster the warmer the temperature, the researchers determined that the effects on metabolism will be greatest in the tropics, even though that region has the smallest actual warming.

In essence, organisms in the tropics show greater effects because they start at much higher temperatures than animals in the Arctic.

They found that temperatures rose fastest in the Arctic, not quite as fast in the northern temperate zone and even more slowly in the tropics.

"Just because the temperature change in the tropics is small doesn't mean the biological impacts will be small. All of the studies we're doing suggest the opposite is true,” Huey said.

In fact, previous research has shown that organisms in temperate and Polar Regions can tolerate much larger increases because they already are used to large seasonal temperature swings.

The scientists said that the effects of warming temperatures in the tropics have largely been ignored because temperature increases have been much greater farther north and because so few researchers work in the tropics.

"I think this argues strongly that we need more studies of the impacts of warming on organisms in the tropics," Michael Dillon, an assistant professor of zoology and physiology, said.

The study has been published in the October 7 edition of Nature.