Planet Likely to Warm by 4C by 2100, Scientists Warn

Temperature rises resulting from unchecked climate change will be at the severe end of those projected, according to a new scientific study.

The scientist leading the research said that unless emissions of greenhouse gases were cut, the planet would heat up by a minimum of 4C by 2100, twice the level the world's governments deem dangerous.

The research indicates that fewer clouds form as the planet warms, meaning less sunlight is reflected back into space, driving temperatures up further still.  The way clouds affect global warming has been the biggest mystery surrounding future climate change.

Professor Steven Sherwood, at the University of New South Wales, in Australia, who led the new work, said: "This study breaks new ground twice:  first, by identifying what is controlling the cloud changes and second, by strongly discounting the lowest estimates of future global warming in favour of the higher and more damaging estimates."

"4C would likely be catastrophic rather than simply dangerous," Sherwood told the Guardian.  "For example, it would make life difficult, if not impossible, in much of the tropics, and would guarantee the eventual melting of the Greenland ice sheet and some of the Antarctic ice sheet", with sea levels rising by many metres as a result.

The research is a "big advance" that halves the uncertainty about how much warming is caused by rises in carbon emissions, according to scientists commenting on the study, published in the journal Nature.  Hideo Shiogama and Tomoo Ogura, at Japan's National Institute for Environmental Studies, said the explanation of how fewer clouds form as the world warms was "convincing", and agreed this indicated future climate would be greater than expected.

Planet Likely to Warm by 4C by 2100, Scientists Warn