The Great Glacier Collapse: Antarctica Just Lost Ice the Size of Los Angeles in a Fraction of a Second

It’s difficult to retain the numbers in your mind. Over the past thirty years, nearly 5,000 square miles of Antarctica’s coastline have seen a retreat in the grounding line, which is the point where ice begins to float on ocean water rather than rest on bedrock. Over the course of three decades of satellite observation from a continent that most people will never see, that area is roughly equivalent to ten cities the size of Los Angeles. On March 2, the UC Irvine researchers who spent years compiling this image published their findings in the Proceedings of the National Academy of Sciences, creating what is, for the first time, a comprehensive circumpolar map that shows precisely where Antarctica is changing and where it isn’t.

The outcome is more complex and, in some respects, more concerning than most climate headlines reveal. The study discovered a very uneven continent, despite the headline figure of 12,820 square kilometers of grounded ice lost since 1996 being real and significant. There is no grounding line migration at all along 77% of Antarctica’s coastline. There, the ice is holding and stable. The damage is being caused by the remaining 23 percent, which is concentrated in areas of East Antarctica, the Antarctic Peninsula, and the Amundsen Sea and Getz sectors of West Antarctica. Understanding these differences is crucial for what comes next because the losses are coming from particular locations with particular vulnerabilities.

The worst of it is in the Amundsen Sea sector. Smith Glacier has moved back 42 kilometers from where it was grounded in 1996. The fastest-melting glacier in Antarctica, Pine Island Glacier, has retreated 33 kilometers. Thwaites Glacier, sometimes referred to as the Doomsday Glacier by climate scientists, has receded by 26 kilometers. When you consider that the entire West Antarctic Ice Sheet could raise sea levels by up to nine feet if it were to collapse, Thwaites already accounts for about 4% of the global sea level rise. That would drastically alter coastlines all over the world. Amsterdam, Jakarta, Mumbai, and Miami. Thwaites is consistently unsettling because of the math involved in that situation. There is no chance that the glacier will crumble tomorrow. It is moving in the wrong direction at a rate that virtually eliminates the possibility of apathy.

“We see the big wounds in Antarctica where warm ocean water is pushed by winds to reach glaciers,” said lead author and NASA JPL scientist Eric Rignot, who has spent decades researching these glaciers. “It’s like the balloon that’s not punctured everywhere, but where it is punctured, it’s punctured deep.” Clinical metaphors are sometimes used by scientists to describe topics that have been the focus of their professional attention for years. In actuality, warm ocean water means that shifting wind patterns, which are connected to more general changes in atmospheric circulation, are directing heat into previously unreachable areas. This heat is then working on ice from below, weakening the shelves that once supported glaciers.

The current study’s methodology makes it more difficult to discount than earlier reports on individual glaciers. The group combined satellite data from several missions, including platforms from the European Space Agency, Canadian RADARSAT systems, Japan’s ALOS/PALSAR-2, Italy’s COSMO-SkyMed, Germany’s TerraSAR-X, and Argentina’s SAOCOM. They also added commercial synthetic aperture radar data from Airbus US and ICEYE, which offered almost daily observations in crucial areas. This is the first grounding line map covering the entire continent over a thirty-year period. Individual glaciers had been documented in earlier studies. The whole picture is what the climate modeling community needs to test its projections, and this work provides it all at once. “Models have to demonstrate they can match this 30-year record to claim credibility for their projections,” Rignot stated. “If a model can’t reproduce this record, the modeling team will need to go back to the drawing board.”

Anyone closely reading this should be uneasy about something that has to do with the northeastern Antarctic Peninsula. There, glaciers such as Edgeworth, Hektoria, Green, Evans, and others have drastically receded. Just Hektoria retreated 21 kilometers from its 1996 position. However, the researchers claim that the retreat patterns in West Antarctica cannot be explained by the warm ocean water intrusion. It’s being driven by something else. They have no idea what. “Something else is acting — it’s still a question mark,” Rignot stated. More unsettling than any of the numbers is the candid admission of an unexplained mechanism in the midst of a peer-reviewed study about sea level futures.

The researchers take care to point out that three-quarters of Antarctica is still stable—that is, it is not performing stability while stealthily retreating. “The flip side is that we should perhaps feel fortunate that all of Antarctica isn’t reacting right now,” Rignot stated, “because we would be in far more trouble.” That sentence’s “but” merits its own space. Under the current circumstances, Antarctica’s stable regions remain stable. It is still unclear what those conditions will be like in twenty or thirty years. The grounding line continues to move. The map is constantly evolving. Future scientists and policymakers will use the record being created now to determine how much time was lost and when.