The central role of diminishing sea ice in recent Arctic temperature amplification

Climate feedback Climate change does not occur uniformly around the world: instead, in a process called polar amplification, the Arctic warms more rapidly than the tropics or mid-latitudes. Recent work published in Nature suggested that upper-atmospheric transport processes accounted for much of the recent polar amplification, but this conclusion proved controversial. Using updated reanalysis data from the past two decades, James Screen and Ian Simmonds now show that reductions in sea ice cover and thickness, rather than upper atmosphere processes, are responsible for most of the recent polar amplification. These findings reinforce suggestions that strong positive ice–temperature feedbacks are at work in the Arctic, and suggest that rapid warming and sea ice melting are likely to continue in the near future.