Monday, June 30, 2008

Climate change: climbing higher

One of the predicted consequences of climate change is that plant and animal species will migrate to follow their preferred temperature range. In particular, due to the regular way temperature changes with altitude, plants will climb uphill, colonising new ground as it becomes warm enough for them to survive in, and retreating from their old range as it becomes too hot for comfort.

It's been happening for a while:

Climate change has caused plants to seek cooler conditions at higher altitudes, scientists suggest.

A study of 171 forest species in mountain ranges of western Europe found that many plants had climbed an average of 29 metres each decade.


"This is the first time that it has been shown that climate change has already had a significant effect on plant species over a wide range of temperatures during the past century," explained Jonathan Lenoir, the paper's lead author.

Of course, there are limits to this process. One is speed of response. Fast-reproducing, short-lifecycle plants like herbs and ferns can respond quickly to temperature. Longer-lived and more slowly reproducing plants like trees can't. So if the temperature changes too rapidly, they may not be able to keep up. The second, of course, is geography: no matter how fast you can move, eventually you run out of mountain (or mountain with soil). And when that happens, there is no option but extinction.