Quantifying the climate carbon feedback

Increasing atmospheric carbon dioxide leads to global warming, which in turn results in a rise in carbon dioxide. This positive feedback in the carbon cycle is of concern to climate scientists, who have previously estimated the sensitivity of the system, and come up with a figure of 40 parts per million by volume of increased carbon dioxide per degree of warming.

New work comparing temperature and carbon records spanning the past millennium, with more than 200,000 individual comparisons, shows that the amplification of global warming by carbon-cycle feedback is significantly less than the previously published estimate.

As in all science, when it comes to climate change there are a number of uncertainties, and the work of Bern University dendrochronologist (tree ring specialist) David Frank and his colleagues appears to have significantly reduced one of the major sources of error. The researchers’ results indicate with 95% confidence that the feedback is at most 21.4 parts per million by volume of carbon dioxide per degree of warming.

Frank’s paper is published in this week’s Nature, along with an informative News and Views article by the superbly named Hugues Goosse.

I’m afraid there’s no time for me to go into this in any more depth, as I have much to do before a business trip next week to the heart of the Eurobeast. It will no doubt be a long and tedious week, and so I would be keen to have recommendations from readers familiar with Brussels for places to go in the evenings, including restaurants that serve vegan food. I can surely find a decent pint without too much trouble.

Further reading

Frank et al., “Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate”, Nature 463, 527 (2010)

Hugues Goosse, “Degrees of climate feedback”, Nature 463, 438 (2010)