High levels of greenhouse-gas emissions could drive the annual sea-ice minimum in the Arctic, which occurs in September, to a level defined as ice-free by around mid-century.

A team led by Jiping Liu of the State University of New York in Albany assessed recent projections from 30 climate models on the basis of how well they represent current sea-ice levels. The researchers also looked at the projections of those models that best represented the evolution of sea ice from 1979–2011. Both analyses suggest that, compared with 2012 levels, sea ice could decline by some 50% to around 1.7 million square kilometres by the 2060s if emissions are moderate. A high-emissions scenario could push the annual minimum to less than 1 million square kilometres — the ice-free level — in the 2050s.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1219716110 (2013)