Fresh research reveals that ocean water is reaching far beneath Antarctica’s Thwaites Glacier, making it more prone to melting than previous estimates suggested.

The interaction of the salty, warm ocean water with the ice is causing significant melting beneath the glacier. This finding could imply that current global sea level rise projections are underestimated, according to a study published Monday in the Proceedings of the National Academy of Sciences.

The Thwaites Glacier in West Antarctica — dubbed the “doomsday glacier” due to its potential impact on the sea level’s rise — is the widest glacier in the world and is roughly the size of Florida. It’s considered the South Pole’s most vulnerable glacier because the land it sits on slopes downward, letting ocean water erode its ice more easily.

Thwaites contributes 4% to the global sea level’s rise and contains enough ice to increase sea levels by more than 2 feet. Because it acts as a natural barrier for the surrounding ice in West Antarctica, its collapse could lead to 10 feet of a sea level rise, posing a threat to coastal communities worldwide.

This latest research introduces a new factor into predictions about the glacier’s future.

A team of glaciologists, led by scientists from the University of California, Irvine, used high-resolution satellite radar data collected from March to June of last year to create an image of the glacier. This let them observe changes in Thwaites’ grounding line, the point where the glacier rises from the seabed and becomes a floating ice shelf.

“In the past, we had only sporadic data to look at this,” Eric Rignot, a professor of Earth system science at UCI and a co-author of the study, told CNN. “In this new data set, which is daily and over several months, we have solid observations of what is going on.”

They observed seawater flowing underneath the glacier for many miles and receding with the tides. When the water flows in, it can lift the glacier’s surface by centimeters, Mr. Rignot said.

He suggested the term “grounding zone” might be more accurate than grounding line, as it can move nearly 4 miles over a 12-hour tidal cycle, according to the research.

The rapid movement of seawater increases glacier melt because as soon as the ice melts, the freshwater is washed out and replaced with warmer seawater. “This process of widespread seawater intrusion will likely increase the projections of sea level rise from Antarctica,” Mr. Rignot said.

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