UP TO two-fifths of the Earth will have a hotter climate by the end of the century, according to a study that predicts the effects of global warming.
The changes — which will have a devastating effect on biodiversity in areas such as the Amazon and Indonesian rainforests — will wipe out numerous animals that are unable to move to stay within their preferred climate range. They will have to evolve rapidly or die out.
Lead author John Williams, of the University of Wisconsin, said: "How do you conserve the biological diversity of these entire systems if the physical environment is changing and potentially disappearing?"
Studies already suggest that animals are shifting towards the poles at six kilometres a decade.
Professor Williams' team used emissions scenarios set out by the Intergovernmental Panel on Climate Change to predict changes in temperature and precipitation.
The team predicts that as the planet warms, climate zones will move towards the poles. To work out the significance of these changes, it compared them with the natural climate variation. It attached greater weight to changes in relatively stable areas. This suggests that some of the worst impacts will be in tropical and sub-tropical regions as they shift to new climatic conditions.
"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," Professor Williams said.
Other studies have suggested the Amazon basin will have an increased risk of forest fires because of its hotter, drier climate.
"One of the things that comes from our paper is that because the species that live in the tropics are adapted or have evolved for a reduced range of variability, it may be that a two to three-degree temperature change in the tropics may be more significant than say a five to eight-degree change in high latitudes," he said.
Up to now, much of the focus of the impact of global warming has been on polar regions because this is where the climate is changing fastest.
The climate model predicts climates will be lost mainly from tropical mountains and the edges of continents nearest the poles.
As the Earth warms, these climate regions have nowhere to go. Some of the losers are the tropical Andes, the African Rift Mountains, the Zambian and Angolan highlands, the South African Cape region, south-east Australia, parts of the Himalayas and the Arctic.
The team reports in Proceedings of the National Academy of Sciences that by 2100, 12 to 39 per cent of the land surface of the Earth will have a new climate, while the combination of climatic conditions on 10 to 48 per cent of the planet will have disappeared altogether. This is using one of the climate change panel's business-as-usual global development scenarios. Using a different scenario that assumes more environmentally friendly development, the corresponding predictions are 4 to 20 per cent.
GUARDIAN
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