Forest fires in the Northern Hemisphere have helped to spur record surface melting of ice in Greenland.

Kaitlin Keegan of Dartmouth College in Hanover, New Hampshire, and her colleagues analysed six shallow ice cores from different areas of Greenland's interior. They found that both the record melting in 2012 and the last similarly widespread melting event in 1889 were caused by a combination of unusually warm air temperatures and increased heat absorption by snow laden with soot from distant forest fires.

Average summer temperatures and the frequency of forest fires in the Northern Hemisphere are projected to rise — and so, by the end of the century, widespread surface melting in Greenland might happen in almost any year, the authors say.

Proc. Natl Acad. Sci. USA http://doi.org/svz (2014)