By Stephen Leahy
UXBRIDGE, Canada, Oct 9, 2009 (IPS)
The prospect of a four-degree Celsius rise in global average temperatures in 50 years is alarming – but not alarmist, climate scientists now believe.
Eighteen months ago, no one dared imagine humanity pushing the climate beyond an additional two degrees C of heating, but rising carbon emissions and inability to agree on cuts has meant science must now consider the previously unthinkable.
“Two degrees C is already gone as a target,” said Chris West of the University of Oxford’s UK Climate Impacts Programme.
“Four degrees C is definitely possible…This is the biggest challenge in our history,” West told participants at the “4 Degrees and Beyond, International Climate Science Conference” at the University of Oxford last week.
A four-degree C overall increase means a world where temperatures will be two degrees warmer in some places, 12 degrees and more in others, making them uninhabitable.
It is a world with a one- to two-metre sea level rise by 2100, leaving hundreds of millions homeless. This will head to 12 metres in the coming centuries as the Greenland and Western Antarctic ice sheets melt, according to papers presented at the conference in Oxford.
Four degrees of warming would be hotter than any time in the last 30 million years, and it could happen as soon as 2060 to 2070.
“Political reality must be grounded in physical reality or it’s completely useless,” John Schellnhuber, director of the Potsdam Institute for Climate Impact Research, told the conference.
Schellnhuber recently briefed U.S. officials from the Barack Obama administration, but he says they chided him that his findings were “not grounded in political reality” and that “the [U.S.] Senate will never agree to this”.
He had told them that the U.S. must reduce its emissions from its current 20 tonnes of carbon per person average to zero tonnes per person by 2020 to have an even chance of stabilising the climate around two degrees C.
China’s emissions must peak by 2020 and then go to zero by 2035 based on the current science, he added.
“Policymakers who agreed to a two-degree C goal at the G20 summit easily fool themselves about what emission cuts are needed,” Schellnhuber said.
Even with a two-degree rise, most of the world’s coral reefs will be lost, large portions of the ocean will become dead zones, mountain glaciers will largely vanish and many other ecosystems will be at risk, Schellnhuber warned. And there is the risk of reaching a tipping point where the warming rapidly accelerates. Continue reading →