AUSTRALIA: Global warming too much for the cold-blooded

Climate change is likely to overheat most 'cold-blooded' animals and survival is likely only for those in habitats that allow them to cool down, a new study indicates. The work by researchers from the universities of Melbourne, Sydney and Wisconsin, took into account animals' ability to seek ideal conditions and regulate their body temperature.

It provides a model that enables researchers to predict how animals on land in any part of the planet are affected by warming and was published in last week's early edition of the Proceedings of the National Academy of Sciences.

"Ectotherms [cold-blooded animals] living in cool parts of the world will be able to spend more time at their favoured body temperatures under climate change, but those living in deserts or tropical forests may struggle to keep their temperatures down," said lead author Dr Michael Kearney from Melbourne's department of zoology.

"We find that for most ectotherms, particularly in tropical areas where biodiversity is greatest, their blood runs hot most of the time and their primary challenge is to avoid overheating. So the impact of global warming on thermoregulating animals will depend critically on how changes in vegetation affect the level of shade available and their capacity to alter the seasonal timing of their breeding," Kearney said.

"Venturing out into the equatorial sun could raise a lizards' body temperature to way over 50 degrees even if it is only 30 degrees in the shade, and in these places the availability of shade, burrows and other cool microclimates, such as water bodies, are critical. Our model allows us to calculate these requirements from first principles."

Kearney said the model could be varied to take into account animals' size, shape, the amount of solar radiation they could absorb, behaviour, activity time (nocturnal or diurnal), and breeding patterns - all of which affected body temperatures.

"We can make similar predictions for endotherms [mammals and birds], in which case we use the model to predict how much water an animal would need to evaporate from its skin or via breathing to keep cool in a heat wave, and from this we can understand what kinds of extremes it can handle".

Comment:
Dinosaurs became extinct when the planet dropped from 22 degrees C to 15 degree C. And you think it is too hot for them? Please people do some research before spouting off this stuff. Cold blooded animals need heat to stay alive.

Eve