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Exclusive News Sci-Tech

Global temperatures to rise 4°C by 2100

Jan 2 (): Scientists from the University of New South Wales estimate that by 2100, the global average temperatures will rise at least 4C and by 2200, the temperature will potentially rise more than 8C if carbon dioxide emissions are not reduced.

Professor Steven Sherwood, at the University of New South Wales Centre of Excellence for Climate System Science, in Australia, who led the new work, said the new study breaks new ground twice : first by finding what is regulating the cloud changes and second by strongly passing over the lowest estimations of upcoming global warming in favour of the higher and more damaging estimates.

Sherwood told 4C would probably be disastrous rather than simply dangerous. For example, in much of the tropics, 4C increase in temperature would make life difficult, if not impossible, and would assure the subsequent melting of the Greenland ice sheet and some of the Antarctic ice sheet, which would ultimately increase the sea levels many metres.

Their research had shown climate models showing a low temperature response to a doubling of carbon dioxide from preindustrial times are not recreating the correct procedures that lead to cloud formation. When the processes were correct in the climate models, the level of climate sensitivity is far higher.

But previously, estimates of the sensitivity of global temperature to a doubling of carbon dioxide ranged from 1.5°C to 5°C. This new research takes away the lower end of climate sensitivity estimates, meaning that global average temperatures will increase by 3°C to 5°C with a doubling of carbon dioxide.

The research has halved the doubt about how much warming is produced by rises in carbon emissions. Tomoo Ogura and Hideo Shiogama, at Japan’s National Institute for Environmental Studies, said the description of how fewer clouds form as the world warms was “undoubted”, and agreed this indicated that future climate would be greater than expected. But they said more challenges lay ahead to narrow down further projections of future temperatures.