Thursday, January 12, 2006
Global warming and latitude - a question of thermal tolerance?
Authors: Tewksbury, J.J., Deutsch, C., Sheldon, K.,, Ghalambor C.,, Huey, R., Haak, D., and Martin, P. R.
Global mean temperatures are projected to increase by 1.4 to 5.8°C by 2100 AD. Recent warming has already altered species distributions, phenology, and persistence, but the impact of warming on species persistence has been difficult to predict. Recent projections often place the largest impacts at higher latitudes, where predicted temperature changes are greatest and organismal responses are larger, yet these projections largely ignore the wide and predictable variance in organismal sensitivity to temperature change. Here we show that the thermal sensitivities of insects, lizards, turtles, and frogs are directly related to the range in temperature these organisms experience. We link these thermal sensitivity relationships to projected temperature change by 2100 AD to create global estimates of terrestrial climate impacts on ectotherms. Contrary to current models, the results presented here incorporate an organisms physiological tolerance and indicate that impacts will be concentrated in equatorial regions, where thermal sensitivities are high, and the majority of diversity is located. These first-order results are robust across taxa and climate models. Thus low-latitude organisms may be more affected by climate change, not because they will experience more extreme temperatures, but because they are adapted to a more narrow range of temperatures.
Joshua Tewksbury is an Assistant Professor in the Department of Biology at University of Washington.