Antarctica Has Lost A Connecticut-Sized Chunk Of Ice In 30 Years

Warm Ocean Water Is Eating Antarctica From Below, Scientists Just Mapped The Damage

Somewhere on the Antarctic ice sheet, an area roughly the size of Connecticut has vanished into the ocean over the past 30 years. That is not a projection or a model output. It is a measured fact, confirmed glacier by glacier: 12,820 square kilometers of grounded ice lost between 1996 and 2025, at a pace of about 442 square kilometers per year.

Grounded ice is the portion of Antarctica’s ice sheet that rests directly on bedrock. When the grounding line retreats, ice that once rested on bedrock begins floating and can flow more quickly into the ocean, contributing to sea level rise. Antarctica holds enough frozen water to raise global sea levels by 57 meters, roughly 187 feet, if it were ever fully lost. No scientist expects that to happen soon, but the rate at which ice is moving toward the ocean determines how fast coastal communities worldwide need to adapt.

A study published in the Proceedings of the National Academy of Sciences assembled one of the most detailed satellite records of Antarctic grounding line change ever produced. West Antarctica drove the bulk of the losses at 62% of the total. East Antarctica contributed 28%. The Antarctic Peninsula made up the rest.

How Scientists Built a 30-Year Record of Antarctica’s Glacier Retreat

Researchers from the University of California Irvine and NASA’s Jet Propulsion Laboratory pulled data from 15 satellites spanning three decades, including the European Space Agency’s Sentinel-1, Canada’s RADARSAT series, Japan’s ALOS PALSAR-2, and commercial satellites from ICEYE. Using a technique called differential synthetic aperture radar interferometry, each satellite bounces radar pulses off the ice surface and detects motion at the level of millimeters. By comparing images taken over time, scientists can track exactly where the boundary between grounded and floating ice sits and how it has shifted year to year.

That boundary is called the grounding line. Ice that crosses it floats, melts, or breaks off as icebergs, contributing directly to sea level rise. Ice still resting on land does not. Across 77% of Antarctica’s roughly 31,390 kilometers of glacier coastline, that line did not move detectably during the study period. In the sectors that did retreat, the distances were severe.

Antarctica Glacier Retreat Was Most Extreme in the West

Smith Glacier pulled back 43 kilometers, the largest single retreat in the dataset. Pine Island Glacier retreated 33 kilometers and shed more than 1,000 square kilometers of grounded ice. Thwaites Glacier, one of the most closely tracked glaciers on Earth for its potential to contribute significantly to sea level rise, retreated 26 kilometers along its fast-flowing core. Haynes Glacier had almost no floating section in 1996 but pulled back 25 kilometers by 2025.

West Antarctic glaciers are retreating two to three times faster than Jakobshavn Glacier in Greenland. Alpine glaciers across Europe retreated at about 39 square kilometers per year between 2000 and 2014, roughly 12 times slower than Antarctica’s current pace.

The engine behind most of this retreat is warm ocean water. Deep in the Southern Ocean flows a current called Circumpolar Deep Water, warmer than the surrounding surface waters. As the authors describe, retreat clusters in areas “where bathymetry channelizes warm Circumpolar Deep Water toward deep grounding zones where beds are retrograde,” meaning the seafloor slopes downward moving inland. Warm water reaching that kind of terrain keeps advancing further each year, melting ice from below and allowing glaciers to accelerate toward the sea.

Not all of Antarctica shares that vulnerability. Large ice shelves covering the Ross Sea and the Filchner-Ronne area showed no measurable retreat. Shallow underwater ridges in those regions appear to block warm water before it can reach the grounding zones, preserving stability across vast stretches of the continent.

East Antarctica’s Glacier Retreat Is Also On the Record

East Antarctica has long appeared more stable than the west, with colder ocean temperatures and more stable geology. The new record shows notable retreat in several glaciers there as well. Vanderford Glacier pulled back 26 kilometers. Totten Glacier retreated 10 kilometers along its glacier side. Denman Glacier showed a 12-kilometer retreat, and in 2021, 2023, and especially 2025, researchers detected long seawater intrusions beneath Denman Glacier extending into one of the deepest bedrock trenches on the continent.

One finding adds nuance to the broader picture. Some retreating glaciers are forming new floating ice shelves behind them as they pull back. Fox and Ferrigno ice streams in West Antarctica, for example, have developed more extensive floating sections today than they had in the past. Those shelves act as a natural brake, resisting the outward flow of continental ice. Whether they hold as the ocean continues to warm is uncertain, but their existence is a reminder that ice loss rarely moves in a straight line.

At 442 square kilometers per year, the pace is already well established. As the authors note, the data “identifies gateways where future retreat is likely to accelerate.” Three decades of satellite evidence now highlight the regions where future retreat may accelerate next.

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