An Arctic Wild Card in the Weather

Has Arctic climate change stacked the deck in favor of more severe winter weather outbreaks in the United States and Europe?Earth's climate system is complex, often responding nonlinearly to both natural and anthropogenic forcings. Some of the feedback processes in these nonlinear responses are straightforward and have predictable consequences. Other feedbacks are less intuitive, occasionally leading to surprises that can catch society unprepared. The severe winter weather experienced in parts of the United States and Europe during the past three years appears to be one of the surprises resulting from enhanced warming of the climate system. New observational and modeling studies (Francis and Vavrus, 2012; Liu et al., 2012) provide strong evidence linking the recent decline in Arctic summer sea ice extent to more frequent winter outbreaks of extreme cold and snowfall in the Northern Hemisphere's middle latitudes.