Half a century of extensive acceleration and grounding line retreat following the ocean driven collapse of Wordie Ice Shelf

Ice shelves restrain the discharge of grounded ice into the ocean, and their break-up plays a major role in Antarctica’s contribution to sea level rise. By combining aerial images from 1966 with modern satellite data, we produce one of the longest and most complete time series of an ice shelf collapse in Antarctica, specifically the Wordie Ice Shelf. Our results indicate that hydrofracturing and rising air temperatures played a minimal role in the collapse. Instead, we detect signs of substantial basal melt since the 1970s, with ice shelf changes correlated with increasing ocean temperatures from 1960-1990. Changes at tributary glaciers occurred at different intervals, with a tripling of surface velocities and grounding line retreats of up to 13 km since 1966. The long record of ice shelf change also demonstrates a heterogeneity in the timing of glacier retreat, mainly correlated with the loss of pinning points and the geomorphology of the Bay. Our results demonstrate that long-term observations of ice shelf collapses are critical for understanding the driving processes and consequences for tributary glaciers.