Antarctic coasts are Experiencing Worrying changes due to an Unexpected ice Collapse

Antarctic coasts are Experiencing Worrying changes due to an Unexpected ice Collapse

East Antarctica is experiencing a hot spot. Nature Geoscience reports that an ice shelf that broke up suddenly a couple of years ago had been steadily weakening for 30 years, largely unnoticed by scientists.

An icy region in Antarctica long considered stable is showing signs of instability, according to satellite observations.

Mathieu Morlighem, a glaciologist at Dartmouth College who wasn’t part of the study, says East Antarctica is ten times larger than West Antarctica.

Antarctica already hemorrhages ice at an alarming rate (SN: 2/15/23). However, if the East Antarctic Ice Sheet retreats as well, sea level rise will be further accelerated.

East Antarctica’s Conger ice shelf, the largest floating glacial ice expanse in the world, reminds us of this concern. As a result of this, several days later it fractured into icebergs.

Catherine Walker, a glaciologist with the Woods Hole Oceanographic Institution in Massachusetts, says no one expected it to go. “There wasn’t even much melting.”

Thousands of years had passed before the Conger ice shelf disintegrated. Glaciers from nearby oozed off the coastline and floated on the ocean. Walker only noticed its collapse in 2022 by chance.

She discovered that the 1,200-square-kilometer Conger ice shelf was present in a satellite photo taken March 10 of that year, but missing in another taken six days later.

We spent two years trying to figure out what happened. Earlier this year, Jonathan Wille and fifty other scientists reported that a powerful storm passed along the coast, tilting the sea surface up and down.

Flexing caused cracks to form along the ice shelf. Fragments were then torn apart by winds. Earth’s warming is likely to intensify [these storms] in the future, says Wille of the Institute for Atmospheric and Climate Science at ETH Zurich.

Stronger storms may damage Antarctica’s coast’s ice shelves (SN: 9/25/19). However, the Conger ice shelf has a different story. According to the new study, it was already in trouble.

During warm temperatures, some ice shelves disintegrated due to massive melting. Seawater drove melting on Conger’s underside due to the generally cold air.

Researchers found a gradual thinning of the floating shelf, from about 200 meters in 1994 to 130 meters in 2021, based on archival satellite measurements.

Salty ocean water permeated into the thin, brittle ice due to cracks, allowing salty water to seep in and weaken it further.

As close to the coast as it could get, the Conger ice shelf was stabilized. With thinned ice shelves, those forces became too strong. In Walker’s words, the island looked like a slow-moving rock.

A research study reports cracks to spiderweb out of the ice shelf’s contact with the island. Then, on March 7, 2022, its detachment from the island left it defenseless against the storm.

Sea level won’t be affected by Conger’s collapse because of its small glaciers. Morlighem’s concern is that it occurred in a supposedly stable part of Antarctica.

It has historically been quite cold along the coastline, but things began to change around 2010. Water that was 0.6 degrees Celsius warmer than before intruded toward the coast last year as ocean currents shifted. Conger’s ice shelf may have succumbed sooner.

If the Denman Glacier collapsed, sea levels would rise 1.5 meters if it all slid into the ocean 130 kilometers to Conger’s west. Nearly half of all the ice in West Antarctica is contained there.

A floating ice shelf and an island slow Denman’s advance into the ocean as it flows off the coastline. Its connection to those stabilizers is slowly thinning. Eventually, it might break free.

Morlighem says this sector has been stable. Over the next century, East Antarctica might even gain mass. It would change everything if Denman and its neighbors destabilized.

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