Climate change will increase extinction risk, study finds

Unique climates and the species that inhabit them may disappear from the Earth entirely due to global warming, computer models suggest.

Changes in regions such as the Peruvian Andes, portions of the Himalayas and southern Australia could have a profound impact on indigenous plants and animals, said John W. Williams, assistant professor of geography at the University of Wisconsin, Madison.

The findings are being published in this week's online edition of the Proceedings of the National Academy of Sciences.

The UN-led Intergovernmental Panel on Climate Change, representing the world's leading climate scientists, reported in February that global warming was an "unequivocal" fact, and that man-made greenhouse gases such as carbon dioxide were "very likely" behind the rise in temperatures.

The IPCC report also found 11 of the highest average recorded global temperatures have come in the past 12 years, and estimated temperatures will rise between 1.8C and4 Cin the next century.

Williams and his research partners used computer models to estimate how various parts of the world would be affected by regional changes consistent with the IPCC's climate models.

"By the end of the 21st century, large portions of the Earths surface may experience climates not found at present, and some 20th-century climates may disappear," the authors wrote.

'Geologically unprecedented'

"The combination of high CO2 concentrations, still-extensive ice sheets in Greenland and Antarctica, and current orbital and landocean configurations are geologically unprecedented."

They suggest isolated climates such as the Peruvian Andes could change drastically enough toto lead tospecies extinctions. And while a new climate might develop in the region as a result of the temperature change, they said, it is unlikely the exact conditions found in it and equally isolated regions would appear elsewhere on Earth.

The climate change might also create novel climates, providing new opportunities for other species to thrive, he said.

Regions where novel climates are expected to form in tropical and subtropical regions include the western Sahara, southeastern U.S. and eastern India.

Alan Robock, a professor of environmental sciences at Rutgers University, said the report was the first he has seen "that not only looks at species extinctions, but also looks at regions where novel climates will appear."

Unforeseen changes

But he cautions the introduction of novel climates may introduce unforeseen changes in neighbouring regions.

"The potential consequences and how these new regimes will be populated are poorly known, and the potential for new threats to humans through disease vectors could be a real danger," he said.

The computer models also found tropical regions such as the rainforests of the Amazon and Indonesia would experience unexpected changes in temperature, results that could be particularly harmful for regions that normally experience little variation in climate.

Williams conducted the research with John E. Kutzbach of the University of Wisconsin, Madison, and Stephen T. Jackson of the University of Wyoming.