Climate sensitivity is unlikely to be less than 2C, say scientists

Climate sensitivity is unlikely to be less than 2C, say scientists

Posted on 2 April 2015 by Guest Author This is a re-post from Roz Pidcock at Carbon Brief

Does the fact that surface temperatures are rising slower than in previous decades mean scientists have overestimated how sensitive the Earth’s climate is to greenhouse gases? It’s a question that’s popped up in the media from time to time. And the short answer is probably no, according to a new paper in Nature Climate Change. Using temperature data up to 2011, the authors work out a value of climate sensitivity of 2.5C, comfortably within the range where scientists have suggested the ‘real’ value lies. Questions about climate sensitivity are complicated, and won’t be solved by any single bit of research. But the new paper seems to contribute to a growing confidence among scientists that climate sensitivity is unlikely to be less than 2C.

A lower limit

Equilibrium climate sensitivity (ECS) is the warming we can expect per doubling of atmospheric carbon dioxide above pre-industrial levels. In 2013, the Intergovernmental Panel on Climate Change (IPCC) estimated the value is likely to lie between 1.5 and 4.5C. This marked a change from previous reports, which put the lower boundary at 2C. The new paper says lowering of the limit was partly “an effect of considering observations over the warming hiatus”. This refers to the last 15 years or so in which surface temperatures have risen slower than in past decades, even though we’re emitting greenhouse gases faster….

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