GLOBAL warming is set to make life distinctly uncomfortable for reptiles and other cold-blooded animals. Unable to produce heat, they rely on strategies such as moving from colder to warmer areas to function. Soon that might not be an option for tropical species.
Many species will need to adapt to climate change to survive, so of the University of Melbourne, Australia, and his team designed a model to get an idea of how cold-blooded species, or ectotherms, would fare. They make up the majority of the world鈥檚 species.
The researchers first assessed how an ectotherm鈥檚 body temperature would change with body shape and colour, and surrounding environment. They then used satellite data to model wind speed, shade and air temperature in a warmer world.
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For most ectotherms, a body temperature of 30 to 35 掳C is ideal, with performance declining at higher and lower temperatures. Above 40 掳C can be lethal.
Kearney鈥檚 model showed that on a summer鈥檚 day in the shade, a 3 掳C rise in average temperature 鈥� the mid-range estimate for the end of this century 鈥� would send the body temperature of ectotherms in Australia鈥檚 tropical deserts over 40 掳C for at least an hour (Proceedings of the National Academy of Sciences, ). When the team ran global simulations, the 3 掳C rise expanded the land area over which ectotherms experience heat stress from 1.6 to 18 per cent.
In the model, ectotherms survived by hiding in burrows for longer, but that could limit their ability to find food, says Kearney. 鈥淓ven if they manage to find shade, they are going to be heat stressed and possibly too hot to reproduce and ultimately to survive,鈥� says of the University of Washington in Seattle.
鈥淓ven if reptiles find shade, they are going to be heat stressed and possibly too hot to reproduce鈥�
