Global warming

Good and bad news in the journal Science this week with regard to the effect of global warming on species.

First the good news:

Individual birds can adjust their behaviour to take climate change in their stride, according to a study by scientists from the University of Oxford. A study of the great tit (Parus major) population in Wytham Woods, near Oxford, has shown that the birds are now laying their eggs, on average, two weeks earlier than half a century ago. The change in their behaviour enables them to make the most of seasonal food: a bonanza of caterpillars that now also occurs around two weeks earlier due to warmer spring temperatures.

Adaptive phenotype plasticity in response to climate change in a wild bird population. Science. 9 May 2008.

and the bad news, reporting on a paper in PNAS:

Because tropical warming will be less extreme, scientists sometimes suppose that tropical species will suffer less from climate change. That's a bad assumption, says Curtis Deutsch, an oceanographer at the University of California, Los Angeles. He notes that temperatures in the tropics are more stable year round than they are at higher latitudes, so tropical organisms--particularly ectothermic, or "cold-blooded," ones like insects--are adapted to cope with a narrow range of temperatures. Their greater sensitivity to temperature variation might put them at risk, even with less warming. Deutsch and his colleagues searched for scientific papers about how insect population growth varies with temperature. They found laboratory data for 38 insect species--including butterflies, beetles, and true bugs--with native ranges that spanned latitudes from 50° north to 40° south. For the locations where each species had been collected, Deutsch and his colleagues looked up the predicted temperature in the year 2100 based on climate change models. They plotted those future temperatures onto the population growth curves and found that, 100 years from now, the reproductive rates of tropical insects could be as much as 20% slower than they are today. Most high-latitude insects, on the other hand, could breed faster, the team reports online today in Proceedings of the National Academy of Sciences. Diminished reproduction could spell extinction for many tropical insect species, unless they adapt or migrate.

Impacts of climate warming on terrestrial ectotherms across latitude Curtis A. Deutsch, Joshua J. Tewksbury, Raymond B. Huey, Kimberly S. Sheldon, Cameron K. Ghalambor, David C. Haak, and Paul R. Martin PNAS | May 6, 2008 | vol. 105 | no. 18 | 6668-6672