Analysis; Alarm over Climate Change
Byline: GUARDIAN NEWS SERVICE
BY the end of the century up to two fifths of the land surface of the Earth will have a hotter climate unlike anything that currently exists, according to a study that predicts the effects of global warming on local and regional climates. And in the worst case scenario, the climatic conditions on another 48% of the land surface will no longer exist on the planet at all.
The changes -- which will have a devastating affect on biodiversity hotspots such as the Amazonian and Indonesian rainforests -- will wipe out numerous species that are unable to move to stay within their preferred climate range. These species will either have to evolve rapidly or die out.
"There is a real problem for conservation biologists," said the lead author, John Williams, at the University of Wisconsin in Madison. "How do you conserve the biological diversity of these entire systems if the physical environment is changing and potentially disappearing?"
Studies already suggest that the ranges of species are shifting towards the poles at around six kilometres a decade, but what will happen when the rate of change intensifies?
His team used emissions scenarios set out by the Intergovernmental Panel on Climate Change (IPCC) -- the international scientific group that advises policymakers -- to predict where changes in temperature and precipitation will occur.
As is already happening, the analysis predicts that as the planet warms climate zones will move north and south towards the poles. To work out the significance of these changes, the team compared them with the climate variation that occurs naturally. They attach greater weight to changes in regions that are relatively stable. This suggests that some of the worst impacts will happen in tropical and subtropical regions as they shift to new climatic conditions not currently seen.
"That's one of the things that really surprised us," said Professor Williams. "The tropics have very little variability from year to year in temperature, they are a very stable climatic zone. So species that live in those climates expect a limited degree of variability. …