A new 30-year study has revealed how Antarctica’s ice is slowly retreating along parts of its vast coastline.
Scientists led by researchers at the University of California, Irvine created the first detailed map showing how the “grounding line” of Antarctica’s ice sheet has moved since the mid-1990s.
Their findings show that while most of the continent remains stable, some regions are losing ice at an alarming rate.
The grounding line marks the place where the massive Antarctic ice sheet lifts off the land and begins floating on the ocean.
Tracking this boundary is important because it tells scientists whether glaciers are stable or retreating.
The research team analyzed three decades of satellite radar data from many international space missions.
By combining these observations, they were able to track grounding line movement all around Antarctica.
The results, published in the journal Proceedings of the National Academy of Sciences, show that about 77 percent of Antarctica’s coastline has remained stable since 1996.
However, the remaining areas tell a different story. The study found that Antarctica has lost 12,820 square kilometers of grounded ice over the past 30 years.
That is roughly equal to ten cities the size of Greater Los Angeles. On average, the continent has been losing about 442 square kilometers of grounded ice each year.
Most of the retreat is happening in specific regions, particularly in West Antarctica, the Antarctic Peninsula, and some parts of East Antarctica.
Some glaciers in West Antarctica have retreated dramatically. For example, Pine Island Glacier moved back about 33 kilometers, Thwaites Glacier retreated 26 kilometers, and Smith Glacier retreated an astonishing 42 kilometers during the study period.
Scientists say much of this retreat is caused by warm ocean water reaching the base of glaciers. Winds can push warmer water toward the Antarctic coastline, where it melts ice from below. Lead author Eric Rignot explained that the damage is concentrated in certain locations rather than across the entire continent.
“It’s like a balloon that isn’t punctured everywhere,” Rignot said. “But where it is punctured, the holes are deep.”
The study relied on data from many satellites operated by space agencies around the world, including the European Space Agency, Canada, Japan, Germany, and Argentina. Commercial radar satellites also played an important role by providing frequent observations of key areas. Together, these datasets allowed scientists to monitor Antarctica in unprecedented detail.
Despite the progress, some mysteries remain. In the northeastern Antarctic Peninsula, glaciers have retreated significantly even though scientists have not detected the warm ocean water that usually causes such changes. Several glaciers in this region have moved many kilometers inland since the 1990s, leaving researchers searching for an explanation.
The new map of grounding line movement will help scientists improve models that predict future sea level rise. For these models to be reliable, they must be able to reproduce the changes that have already occurred over the past three decades.
The study also provides some reassurance. Because most of Antarctica’s coastline has remained stable, the continent is not yet responding everywhere to warming conditions.
Still, scientists warn that the situation could change. If more parts of Antarctica begin to retreat, the consequences for global sea levels could become far more serious in the future.
