Global warming could cause colder winters

Science : Although it may seem counterintuitive, warmer-than-average summers may trigger more severe winter cooling and excessive snowfall, writes Sid Perkins for Science. The relationship showed itself in a new study published in Environmental Research Letters by Judah Cohen and colleagues at the consulting firm Atmospheric and Environmental Research in Lexington, Massachusetts. Warming in the Arctic in recent decades, along with other factors, has caused widespread melting of sea ice. More open water has led to more evaporation and increased cloudiness over the Arctic Ocean. That, in turn, can trigger increased snow coverage in Siberia as early as October. The Arctic Oscillation then steers the frigid air from Siberia southward to midlatitude regions throughout the winter. Researchers hope that by incorporating better accounts of autumn Siberian snow-cover variability into climate models, they will be able to provide more accurate winter weather forecasts.