In a startling reappraisal of the threat, James Hansen, head of the Nasa Goddard Institute for Space Studies in New York, calls for a sharp reduction in C02 limits.
Hansen says the EU target of 550 parts per million of C02 - the most stringent in the world - should be slashed to 350ppm. He argues the cut is needed if "humanity wishes to preserve a planet similar to that on which civilisation developed". A final version of the paper Hansen co-authored with eight other climate scientists, is posted today on the Archive website. Instead of using theoretical models to estimate the sensitivity of the climate, his team turned to evidence from the Earth's history, which they say gives a much more accurate picture.
Smokestack in Detroit, "Gyre," Wikimedia Commons