Q&A: What’s Next With the Brunt Ice Shelf Break? And What About the Penguins?

February 3, 2023 By Eric Williamson, williamson@virginia.edu Eric Williamson, williamson@virginia.edu

Recent satellite footage showed a gigantic chunk of ice the size of London – or twice the size of New York City – break off from the Brunt Ice Shelf in Antarctica.

While the headlines were dramatic, the news coverage stressed that the break was expected and not directly related to climate change.

UVA Today asked Lauren Simkins, a glacial geologist at the University of Virginia, to put the ice shelf development into perspective.

“While the one iceberg alone isn’t cause for alarm, sustained changes and rapid disintegration of ice shelves do have great significance for the ability of a floating ice shelf to hold back upstream ice from flowing into the ocean,” Simkins said.

The professor also explained what ice shelves are, looked at the implications for the future of the ice shelf and updated us on the fate of the emperor penguins who lived there.

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Q. What is an ice shelf?

A. As glaciers on land flow into the ocean, floating ice shelves can form and jut out into the ocean. The vast majority of ice shelves that exist today are on the fringes of Antarctica.

Ice shelves and ice blocks, known as icebergs, that break off of ice shelves do not contribute to sea-level rise. That’s because their volumes have already been compensated for in the ocean at the initial point of floatation, when glacier ice left land and began to float in the ocean.

However, ice shelves protect upstream glaciers by acting as a physical barrier to slow down glacier ice flow into the ocean and, thus, dampen glacier sea-level contributions.

Q. Since the Brunt Ice Shelf break is not attributed to climate change, is it a problem?

A. A crack in the Brunt Ice Shelf initiated in the 1970s and has continued to grow each year since 2012; therefore, the massive, London-sized iceberg that broke free on Jan. 22 has been in the making for decades.

It is normal for icebergs to break off ice shelves, yet an increase in the frequency of cracking and area of broken ice can be a sign of climate change – specifically, a warming of the ocean in which the ice shelf is floating or warming of the atmosphere, which can cause melting of the top of an ice shelf, and thus to further crack propagation.

Q. What do scientists think will happen next?

A. Time will tell how the Brunt Ice Shelf responds to the loss of this iceberg and whether increased calving and breaking will happen.

We do know that climate change can lead to positive feedbacks that lead to more cracking, more iceberg production and less stable ice shelves that may disintegrate entirely. A recent study and complementary op-ed I wrote about it, both published in Nature Climate Change, dive deeper into the importance of ice shelves and the ways in which they change.

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Q. Are the emperor penguins on the ice shelf safe?

A. In the case of the recent iceberg, named A-81, from the Brunt Ice Shelf, there has been worry that a nearby emperor penguin colony would be damaged. The penguins built their colony on sea ice, formed by the freezing of ocean water, that is at the margin of the Brunt Ice Shelf.

Now we can see from space, based on their distinct-color guano, that their colony has survived. Yippie!

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Eric Williamson

University News Senior Associate University Communications