Sensitivity of 21st century sea level to ocean-induced thinning of Pine Island Glacier, Antarctica

Pine Island Glacier (PIG), Antarctica, is rapidly losing mass, supporting arguments that it may play a major role in 21st century sea-level rise. Yet this glacier's quantitative contribution to sea level based on theoretical and computational models is poorly known. We have developed a basin-scale glaciological model to examine the sensitivity of PIG to a range of environmental forcings. While oceanic melt likely played the leading role in recent thinning and retreat, we find that the particular grounding-line geometry with an extended ice plain in the 1990s made it susceptible to such forcing. Our model further indicates that while the rate of grounding-line retreat should diminish soon, the glacier's mass loss may continue at rates similar to, or moderately elevated from, the present. While substantial, our model-derived maximum rate of 2.7 cm/century is considerably smaller than previous heuristically-derived bounds on the sea-level contribution.