TY - JOUR T1 - Summer melt regulates winter glacier flow speeds throughout Alaska JF - Geophysical Research Letters Y1 - 2013 A1 - Evan W. Burgess A1 - Chris F. Larsen A1 - Richard R. Forster KW - Alaska KW - Ice Dynamics KW - Mountain Glaciers KW - Offset Tracking KW - Sub-Glacial Hydrology KW - Winter AB - Predicting how climate change will affect glacier and ice sheet flow speeds remains a large hurdle towards accurate sea level rise forecasting. Increases in surface melt rates are known to accelerate glacier flow in summer, whereas in winter, flow speeds are believed to be relatively invariant. Here we show that wintertime flow speeds on nearly all major glaciers throughout Alaska are not only variable but are inversely related to melt from preceding summers. For each additional meter of summertime melt, we observe an 11% decrease in wintertime velocity on glaciers of all sizes, geometries, climates and bed types. This dynamic occurs because inter-annual differences in summertime melt affect how much water is retained in the sub-glacial system during winter. The ubiquity of the dynamic indicates it occurs globally on glaciers and ice sheets not frozen to their beds and thus constitutes a new mechanism affecting sea level rise projections. UR - http://dx.doi.org/10.1002/2013GL058228 ER -