Antarctica lost 10 times Greater Los Angeles in ice over 30 years

Antarctica has lost almost 13,000-square-kilometres of grounded ice over the past three decades — an area equal to nearly 10 times the size of Greater Los Angeles — as key sectors of the continent’s coastline quietly retreat under mounting ocean pressure.

It’s the headline figure to have emerged from a comprehensive 30-year satellite analysis led by glaciologists at the University of California, Irvine, who have produced – for the first time – a circumpolar map of Antarctic grounding line migration.

The grounding line — or in layman’s terms the point at which the ice sheet lifts off bedrock and begins to float — is one of the most critical indicators of long-term ice sheet stability and future sea-level rise.

The study, published in Proceedings of the National Academy of Sciences, shows that while 77% of Antarctica’s coastline has remained stable since 1996, concentrated losses in West Antarctica, the Antarctic Peninsula and parts of East Antarctica have driven a steady net retreat. On average, 442-square-kilometres of grounded ice have been lost each year.

“The grounding line is where continental ice meets the ocean, and measuring the movement of grounding lines with satellite-based synthetic aperture radar has been our gold standard for documenting ice sheet stability,” said lead author Eric Rignot, UC Irvine Distinguished Professor and Donald Bren Professor of Earth system science.

“We’ve known it’s critically important for 30 years, but this is the first time we’ve mapped it comprehensively across all of Antarctica over such a long time span.”

The most dramatic changes were recorded in West Antarctica’s Amundsen Sea and Getz sectors. Pine Island Glacier retreated 33 kilometres, Thwaites Glacier 26 kilometres, and Smith Glacier an extraordinary 42 kilometres from their 1996 grounding line positions.

“Where warm ocean water is pushed by winds to reach glaciers, that’s where we see the big wounds in Antarctica,” explained Rignot, who is also a senior research scientist at NASA Jet Propulsion Laboratory. “It’s like the balloon that’s not punctured everywhere, but where it is punctured, it’s punctured deep.”