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. Editor's summary: Glacial responses to rising temperatures on time scales of decades and longer are clear: As the world warms, glaciers retreat. The general relation between temperature and ice behavior also can be seen over shorter intervals in the rates at which glaciers flow. Greene and Gardner analyzed seasonal ice sheet and glacier dynamics for every body of land ice on Earth greater than 5 square kilometers in area using more than 36 million unique pairs of high-resolution optical and radar satellite images collected between 2014 and 2022 (see the Perspective by Ultee). These data reveal the influence of surface melting and point to how additional warming could affect seasonal glacial cycles worldwide. —Jesse Smith [ABSTRACT FROM AUTHOR]