{"id":933069,"date":"2026-10-18T22:46:13","date_gmt":"2026-10-18T22:46:13","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/933069\/"},"modified":"2026-10-18T22:46:13","modified_gmt":"2026-10-18T22:46:13","slug":"something-unexpected-is-happening-to-antarcticas-collapsing-ice-cliffs","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/933069\/","title":{"rendered":"Something Unexpected Is Happening to Antarctica\u2019s Collapsing Ice Cliffs"},"content":{"rendered":"

\"Melting<\/a>Antarctica\u2019s towering ice cliffs may be more resilient than scientists once feared. New satellite observations reveal surprising natural mechanisms that could reshape predictions of future sea level rise. Credit: Shutterstock<\/p>\n

Satellite observations show Antarctic ice cliffs stabilizing after unexpectedly rapid collapse, challenging assumptions about runaway ice loss and its contribution to rising seas.<\/p>\n

Antarctica\u2019s ice shelves help hold back the ice sheet behind them, but rising temperatures are causing these supports to melt and break apart at record rates. As sheer ice cliffs are left exposed, scientists have worried that a collapse could reveal a taller cliff farther inland, setting off a chain of failures that eats into the ice sheet and raises seas worldwide.<\/p>\n

In a four-year satellite survey of more than 15,000 Antarctic ice cliffs, researchers at MIT and the Woods Hole Oceanographic Institution (WHOI) found that the tallest cliffs they examined closely did collapse, and the ice sheet in those regions retreated faster than models predicted. \u201cBut that retreat was short-lived,\u201d says Caroline Needell, a graduate student in the MIT-WHOI Joint Program.<\/p>\n

Needell conducted the study, published in Science, with Catherine Walker, an assistant scientist at WHOI, and Jeremy Bassis, an associate professor at the University of Michigan.<\/p>\n

Rapid collapse without runaway retreat<\/p>\n

The observations came from NASA\u2019s Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), which passes over Earth\u2019s polar regions. Its laser altimeter measures the height of ice sheets, glaciers, and sea ice, as well as ocean levels in and around Antarctica. The team analyzed measurements collected every three months from 2019 to 2023 to determine how tall the cliffs were and how they changed over time.<\/p>\n

Those measurements offered a much broader test of a proposed process called marine ice cliff instability, or MICI. In this scenario, a cliff exceeding a critical height collapses under its own weight. If that exposes a taller cliff, the failures continue inland. Previous studies had investigated this process by modeling ice\u2019s physical properties, scaling those relationships up to entire cliffs, and combining the predictions with a few observations from Antarctica.<\/p>\n

\"Ice<\/a>Researchers at MIT and the Woods Hole Oceanographic Institution (WHOI) analyzed over 15,000 ice cliffs in Antarctica to reveal how they behave over time. Credit: Caroline Needell<\/p>\n

\u201cPredictive ice-sheet models that have been used so far to represent ice cliff instability just take into account cliff height,\u201d Needell notes. \u201cThat\u2019s the only variable that matters. And once the cliff height reaches the critical threshold, usually 100 meters, it should initiate this runaway effect of ice sheet retreat.\u201d<\/p>\n

Across the satellite survey, the average ice cliff stood about 30 meters (98 feet) tall, well below that proposed threshold. A few rare cliffs exceeded 100 meters (328 feet), roughly the height of the Statue of Liberty, giving the researchers an opportunity to examine what happened near and above the predicted danger point.<\/p>\n

\u201cAfter we did that global analysis, we thought, ok, let\u2019s zoom in on the tallest cliffs and see how they\u2019re behaving,\u201d Needell says.<\/p>\n

The team focused on four cliffs in four regions around the Antarctic ice sheet. These cliffs were roughly 100 meters tall, with the tallest reaching 127 meters (417 feet). Tracking them through the same four years of measurements revealed that their rapid collapse and retreat did not continue unchecked. The ice eventually spread back out toward the ocean.<\/p>\n

\u201cIt\u2019s this rapid retreat, punctuated by periods of stabilization,\u201d Needell says. \u201cThat was puzzling to us. Then, we thought: We need to look at all the things that affect cliff height.\u201d<\/p>\n

Rising ground can stabilize ice cliffs<\/p>\n

The researchers first examined the shape of the land beneath the ice. Over relatively flat ground, changes in the ice surface\u2019s elevation reflect changes in the thickness of the ice itself. Where the ground rises, however, some of that elevation comes from the land underneath, leaving a thinner layer of ice above it. Such a rise could act as a speed bump for retreat by making the overlying ice less prone to collapse. When the team checked Antarctic topographic measurements, they found that cliffs stabilized around places where the underlying land rose.<\/p>\n

Taller cliffs also \u201cthin out\u201d faster, the researchers found. As they collapse, they settle into shorter, more stable cliffs, limiting further collapse.<\/p>\n

\u201cNow we know what to look for,\u201d Needell says. \u201cWe really need to know the bed topography, and we need to know the ice thinning rate, in order to get ice cliff instability right, because this value really matters in the context of projecting sea level rise.\u201d<\/p>\n

Support from broken ice and seawater<\/p>\n

Conditions in front of the cliffs offered additional clues. In the broader survey, cliffs that stayed roughly in place had thicker m\u00e9lange, the slushy mixture of broken icebergs and sea ice that collects against a cliff\u2019s ocean-facing edge.<\/p>\n

\u201cWe measured m\u00e9lange height and found taller cliffs have thicker m\u00e9lange, which could be a built-in stabilizing effect,\u201d Needell explains.<\/p>\n

The satellite data also indicated that deeper surrounding water could help keep a cliff standing. The water buoys the ice and pushes back against it, providing support that can make collapse less likely.<\/p>\n

\u201cWe found that when the cliffs were retreating, they were doing so faster than what has been modeled, which would mean more ice loss and higher contributions of sea level rise,\u201d Needell says. \u201cBut because we found that the retreat was short-lived, and all the glaciers eventually stabilized, that would suggest that things won\u2019t be so bad. We don\u2019t see this runaway effect.\u201d<\/p>\n

Reference: \u201cEmpirical constraints on ice cliff calving\u201d by Caroline Needell, Catherine C. Walker and Jeremy N. Bassis, 15 October 2026, Science.
DOI: 10.1126\/science.aee0658<\/a><\/p>\n

This research was supported, in part, by NASA, the U.S. National Science Foundation, and the DOMINOS project, a component of the International Thwaites Glacier Collaboration.<\/p>\n

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