Seasonal dynamics of Earth’s glaciers and ice sheets

The sensitivity of Earth’s glaciers to environmental change is on display each year as they change speed with the seasons, and a glacier’s response to warming from winter to summer may help predict its response to warming on multiyear timescales. We present a global analysis of seasonal glacier and ice sheet dynamics, finding that seasonal velocity amplitudes are greatest where annual maximum surface temperature exceeds 0°C. We see evidence of basal hydrological systems affecting glacier flow on seasonal timescales and find a weak but significant global correlation between seasonal and interannual flow variability. Glaciers appear to accelerate and decelerate yearly in response to surface melt, and the data suggest that future atmospheric warming could amplify and alter the timing of seasonal glacier dynamics worldwide.