A new study suggests some Antarctic ice shelves may be melting much faster from below than scientists expected. Research published in Nature Communications shows that channels underneath the ice can trap warmer seawater, increasing melting in places that help hold back massive glaciers.
The study focused on the Fimbulisen Ice Shelf in East Antarctica, an area usually seen as colder and more stable than other parts of the continent. Researchers found that even relatively small amounts of warmer water could have a strong impact once they entered these underwater channels.
Ice shelves are floating extensions of glaciers. They act a bit like giant barriers, slowing the flow of ice from the continent into the ocean. If they weaken, glaciers behind them can move faster, adding more ice to the sea and pushing sea levels higher worldwide.
Warm Water Gets Trapped Beneath The Ice
To understand what was happening under the ice shelf, the team combined detailed mapping with high-resolution ocean modeling. What they found was surprisingly specific: long grooves carved into the underside of the ice shelf can trap warmer water instead of letting it circulate away.
That trapped heat causes melting to intensify locally. In some parts of the channels, melt rates increased by about an order of magnitude compared with smoother sections beneath the shelf. Lead author Tore Hattermann from the iC3 Polar Research Hub in Tromsø said the shape of the ice itself plays an active role in the process.
“We found that the shape of the ice shelf underside is not just a passive feature. It can actively trap ocean heat in exactly the places where extra melting matters most,” Hattermann said.
The researchers compared several scenarios, including smoother ice bases and more realistic channel-shaped ones, under cooler and slightly warmer ocean conditions. The difference was clear in the simulations.
A Weak Spot in East Antarctica
The findings are drawing attention because they come from East Antarctica, a region often viewed asless vulnerable than the western side of the continent. The study found that even modest inflows of warmer deep water were enough to sharply increase melting inside the channels beneath the Fimbulisen Ice Shelf.
“We observed beneath the Fimbulisen Ice Shelf that even small amounts of warmer water can substantially increase melting within the channels,” Hattermann explained. “As a result, the channels can grow and, in the worst case, weaken the stability of the entire ice shelf.”
Co-lead author Qin Zhousaid the results show that colder Antarctic ice shelves may still be highly sensitive to ocean changes.
“What is striking is that even modest inflows of warmer deep water can have a large effect when the ice shelf base is channeled,” he said.
That point stood out in the study. Scientists have known for years that warmer oceans threaten Antarctic ice, but this research suggests the underside geometry of the shelves may make some areas melt faster than expected.
Climate Models May Be Incomplete
The researchers say many current climate and ice-sheet models do not properly account for these narrow channels beneath the ice shelves. The study, published in Nature Communications, notes that uneven melting can weaken the deeper parts of the ice shelves, reducing their ability to hold glaciers in place. Once weakened, more ice can flow into the ocean.
Hattermann warned that this limitation could lead scientists to underestimate how “cold” Antarctic ice shelves respond to warming coastal waters.
“Current climate models do not capture this effect,” he said, addingt that: “this means that they risk underestimating the sensitivity of the ‘cold’ ice shelves along East Antarctica’s coastline to small changes or warming in coastal waters. Such changes have already been observed, and are projected to increase in the future.”
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