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Tuesday, May 4, 2010

S. C. Sherwood & M Huber, PNAS, An adaptability limit to climate change due to heat stress

Proceedings of the National Academy of Sciences,

An adaptability limit to climate change due to heat stress

Steven C. Sherwood* (Climate Change Research Centre, University of New South Wales, Sydney, New South Wales 2052, Australia) and Matthew Huber (Purdue Climate Change Research Center, Purdue University, West Lafayette, IN 47907, U.S.A.)

Edited by Kerry A. Emanuel, Massachusetts Institute of Technology, Cambridge, MA, and approved March 24, 2010 (received for review November 19, 2009).


Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature TW, is surprisingly similar across diverse climates today. TW never exceeds 31 °C. Any exceedence of 35 °C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global-mean warming of about 7 °C, calling the habitability of some regions into question. With 11–12 °C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12 °C are possible from fossil fuel burning. One implication is that recent estimates of the costs of unmitigated climate change are too low unless the range of possible warming can somehow be narrowed. Heat stress also may help explain trends in the mammalian fossil record.

*Correspondence e-mail:



jyyh said...

I think the lizards and other cold-blooded animals will somewhat like it if they find enough water. Birds have a higher core temperature than f.e. humans, so they could manage better. Mammals on the other hand are based on constant temperature reactions going steadily on, so the less cold extremes will benefit other classes of animals. Anyone in croc farming, edible lizard, snake farming, possibly fish/shrimp farming (if one can find a spot clean enough) should do quite ok... :-|. Kangaroos (if I remember correctly) have also a quite high core temp, so a switch from cows to kangaroos might be considered... on the other hand I don't know anything about kangaroo diseases.

jyyh said...

was wrong about the kangaroo (core temp 36C, but they ve got a very efficient heat transfer present.