An extensive new satellite analysis shows that Antarctica has lost nearly 12,950 square kilometers of ice over the past three decades – an area roughly twice the size of Delaware – as warming ocean waters erode the continent’s most vulnerable edges.
Led by researchers at the University of California, Irvine, the study tracks how Antarctica’s “grounding line” — the boundary where ice anchored to bedrock begins to float on the ocean — shifted between 1992 and 2025. Because that boundary marks where land-based ice begins to contribute directly to sea-level rise. ice sheet instability and future loss of ice mass.
Rignot and his colleagues analyzed data from a wide range of satellite missions operated by European, Canadian, Japanese, Italian, German and Argentinian space agencies. Using radar instruments, the researchers tracked the vertical movements of floating ice shelves caused by ocean water. The grounded ice remained fixed to the bedrock, allowing them to locate shifts in the grounding line over three decades with unprecedented precision.
The results show that around 77% of the Antarctic coastline experienced no detectable grounding line migration since 1996, suggesting broad stability across much of the continent. But in vulnerable areas, particularly parts of West Antarctica, the Antarctic Peninsula and parts of East Antarctica, the study found “significant withdrawal.”
The biggest changes were detected along the coast of the Amundsen Sea in West Antarctica and in the Getz sector, where the fault line in some places retreated as much as 42 km during the study period.
The retreat was most pronounced where deep underwater channels channel warm ocean water towards the bottom glaciersRignot said. The warmer water melts ice from below, thinning floating shelves and weakening their ability to support the glaciers behind them.
“It’s like the balloon that isn’t punctured everywhere, but there is punctured, it’s punctured deep,” Rignot said.
The study also highlights a puzzling pattern along the northeastern Antarctic Peninsula. In that area, several ice shelves collapsed before the study period, and several glaciers have since retreated significantly, but scientists lack clear evidence that warm ocean water is driving the change.
“Something else is acting — it’s still a question mark,” Rignot said in the statement.
As well as documenting what has already happened, the researchers say the new record provides a crucial reality test for computer models used to project the future sea level rise.
“Models must demonstrate that they can match this 30-year record to claim credibility for their projections,” Rignot said in the statement. “That’s the real value of this observational record: knowing that this ground line migration has occurred.”
While much of Antarctica remains stable, Rignot warned that the current balance may not hold indefinitely.
– The downside is that perhaps we should feel lucky that the whole of Antarctica is not reacting right now, because we would be in far more trouble, he said. “But that could be the next step.”
This research is described in a paper published March 2 in the journal Proceedings of the National Academy of Sciences.
