Recent weather extremes during summer in the Northern Hemisphere, such as the 2012 drought in the United States (pictured), seem to be linked to loss of Arctic sea ice and reductions in snow cover.

Qiuhong Tang of the Institute of Geographic Sciences and Natural Resources Research in Beijing and his colleagues compared meteorological records with satellite observations of snow and ice. They found that Arctic sea-ice retreat and, to a lesser degree, decreased snow cover alter large-scale atmospheric circulation patterns — for example, by shifting the jet stream northwards. These changes typically cause heatwaves and other extreme weather events at mid-latitudes.

The results could help to improve seasonal and longer-term climate forecasts, the team says.

Credit: VICTOR J. BLUE/BLOOMBERG VIA GETTY

Nature Clim. Change http://doi.org/qds (2013)