Scientists Find Common Ground over Climate Sensitivity

A new paper helps to shed light on one of the biggest questions in climate science:  how much the climate will warm in future?

The answer to this depends a lot on something scientists call the “climate sensitivity” – a measure of how much the climate warms in response to greenhouse gases.

Until now, scientists have been grappling with how to reconcile the fact that different ways to estimate the climate sensitivity have, so far, come up with quite different answers.

This uncertainty has never been a reason to question whether climate change will be serious or to delay action to tackle emissions, though it has often be misused by climate skeptics this way.

But a question mark over the value of climate sensitivity has meant that projections of future temperature rise are less precise than scientists would like.  It also makes it harder to gauge our chances of staying below a given temperature limit, such as 2C above pre-industrial levels.

A new paper published in Nature Climate Change says there is, in fact, no disagreement between the different methods after all.  In reality, they measure different things and once you correct for the fact that the historical temperature record underestimates past warming, the gap closes.

The implications are significant since it suggests we’ve seen around 0.2C more warming than previously thought, says co-author Dr Ed Hawkins in his Climate Lab Book blog.

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