A new study examining nearly 40 years of satellite imagery has revealed that the floating ice shelves of a critical portion of West Antarctica are steadily losing their grip on adjacent bay walls, potentially amplifying an already accelerating loss of ice to the sea.

The most extensive record yet of the evolution of the floating ice shelves in the eastern Amundsen Sea Embayment in West Antarctica shows that their margins, where they grip onto rocky bay walls or slower ice masses, are fracturing and retreating inland.

As that grip continues to loosen, these already-thinning ice shelves will be even less able to hold back grounded ice upstream, according to glaciologists at The University of Texas at Austin’s Institute for Geophysics (UTIG).

Reporting in the Journal of Glaciology, the UTIG team found that the extent of ice shelves in the Amundsen Sea Embayment changed substantially between the beginning of the Landsat satellite record in 1972 and late 2011.

These changes were especially rapid during the past decade. The affected ice shelves include the floating extensions of the rapidly thinning Thwaites and Pine Island Glaciers.

 Photo:  Pairs of Landsat satellite images showing changes in ice shelf margins in the eastern Amundsen Sea Embayment in West Antarctica between 1972 and 2011.

The striping visible in the 2011 images is due to an unrepaired malfunction in the Landsat-7 platform that occurred in 2003.