A new paper suggests we have been greatly underestimating the impacts of climate change – and the size of the necessary response.
Rather than taking thousands of years to melt, as the IPCC predicts, Hansen and his team find it “implausible” that the expected warming before 2100 “would permit a West Antarctic ice sheet of present size to survive even for a century.” As well as drowning most of the world’s centres of population, a sudden disintegration could lead to much higher rises in global temperature, because less ice means less heat reflected back into space. The new paper suggests that the temperature could therefore be twice as sensitive to rising greenhouse gases than the IPCC assumes. “Civilization developed,” Hansen writes, “during a period of unusual climate stability, the Holocene, now almost 12,000 years in duration. That period is about to end.”(4)