Friday, December 25, 2009

Running, Not Walking

Visualize the planet as a globe. Now put a belt around it. Put another belt above and below that one. These are climatic zones; and they are expanding. The belt around the middle is widening, and the one above and the one below are slipping up towards the poles as the middle one gets bigger. How fast is this happening? About 0.42 kilometres (0.26 miles) per year. But that speed is not constant. To quote from the Carnegie Institute for Science release:
The researchers found that as a global average, the expected temperature velocity for the 21st century is 0.42 kilometers (0.26 miles) per year. But this figure varies widely according to topography and habitat. In areas of high topographic relief, where species can find cooler temperatures by climbing a nearby mountain, velocities are relatively low. In flatter regions, such as deserts, grasslands, and coastal areas, species will have to travel farther to stay in their comfort zone and velocities may exceed a kilometer per year.
That's fast. Forests may have moved that fast after the last ice age, but they didn't then face the fragmented landscape they now face. Agricultural land, cities, etc. mean that a lot of species--not just plants and trees, but vertebrates and invertebrates--may have simply nowhere to go. The question is not whether they can adapt to shifting climate zones, but whether they can move with the zone they currently live in.  Below is an interview with Chris Field, director of the Carnegie Institution’s Department of Global Ecology and a co-author of the study on the speed of climate movement.

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