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Sea Level Rise Projections Nearly Double Due to West Antarctic Ice Sheet

Landsat 8 natural-color mosaic of the ice cliff at the terminus of Thwaites Glacier, West Antarctica on Jan. 9. Knut Christianson:USGSPolar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6–9 meters higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago).

In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics—including previously under appreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios.

Antarctica has the potential to contribute more than a meters of sea-level rise by 2100 and more than 15 meters by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years. View the full report here.

(Headline image: Landsat 8 natural-color mosaic of the ice cliff at the terminus of Thwaites Glacier, West Antarctica on Jan. 9. (Knut Christianson/USGS))

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