webcomber

scinerds:

Hyperwarming Climate Could Turn Earth’s Poles Green

An Era of ice that has gripped Earth’s poles for 35 million years could come to an end as extreme global warming really begins to bite. Previously unknown sources of positive feedback - including “hyperwarming” that was last seen on Earth half a billion years ago - may push global temperatures high enough to send Earth into a hothouse state with tropical forests growing close to the poles.

Climate scientists typically limit themselves to the 21st century when predicting how human activity will affect global temperatures. The latest predictions are bolder, though: the first systematic forecasts through to 2300 are beginning to arrive.

They follow four possible futures, including one in which we rapidly cut emissions and another in which we burn fossil fuels into the 22nd century (Climatic Change, DOI: 10.1007/s10584-011-0157-y).

Chris Jones of the UK Met Office in Exeter says that unpublished results suggest the “burn everything” scenario could see atmospheric carbon dioxide levels reach 2000 parts per million - the figure today is 388 ppm. That pulse of CO2 could lead to a global temperature rise of 10 °C.

Temperatures this high were last seen in the Eocene, 34 million years ago, says Paul Pearson of Cardiff University in the UK. Conditions were so different back then that the Canadian High Arctic was populated by plants that are now found in the south-eastern US (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2011.1704).