Sci. Adv. 3, e1701681 (2017)

The stability of the Antarctic Ice Sheet and its potential contribution to global sea-level rise under climate change is uncertain. The East Antarctic, with greater ice mass, is thought to be more stable. However, the Totten Glacier, which includes the floating Totten Ice Shelf (TIS), has shown changes in its ice velocity, thickness and grounding line location.

To determine the drivers of changes in the TIS, Chad Greene from the University of Texas at Austin, USA, and co-authors use satellite images to generate a 14-year time-series of ice velocity and compare to oceanic wind stress calculated from reanalysis data. They show that wind stress causes upwelling of warm, salty water — modified Circumpolar Deep Water (mCDW) — further verified by in situ observations from the continental shelf. A 19-month time delay from upwelling to accelerated ice flow is apparent; this time is needed for mCDW to cross the continental shelf, reach under the TIS, and cause melt to facilitate flow.

These results highlight that warmer ocean and air temperatures are not the only risk to glacial stability, with changes in surface winds potentially influencing ocean circulation, bringing warm waters into contact with ice shelves.