More than a third of the Antarctic ice shelf could collapse this century

In a new study from the University of Reading, scientists warn that much of the Antarctic ice shelf is at risk of collapsing as the climate continues to warm. The experts report that if the global average temperature reaches 4 degrees Celsius above pre-industrial levels, more than one-third of the ice sheet could lose its stability. 

The investigation into the vulnerability of the floating ice surrounding Antarctica is the most detailed of its kind. The team used high-resolution regional climate modeling to predict the impact of increased melting and water runoff on ice shelf stability.

According to the study, four degrees of warming would destabilize around half a million square kilometers of ice across Antarctic ice shelves, which is 34 percent of the total area. The area that is threatened includes 67 percent of the ice shelf area on the Antarctic Peninsula.

The researchers identified four Antarctic ice shelves that would be particularly threatened in a warmer climate, including Larsen C – the largest remaining ice shelf on the peninsula.

“Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea,” said Dr. Ella Gilbert.

“We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly. Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modeling techniques to fill in the finer detail and provide more precise projections.”

“The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise.”

Ice shelf vulnerability was analyzed under four conditions: 1.5°C, 2°C and 4°C global warming scenarios, all of which are possible during this century.

Ice shelves are formed where glaciers flow off the land and meet the sea. The floating platforms of ice are attached to areas of the coastline. 

In the summer, ice at the surface of the shelf melts into small air gaps in the snow layer below, where it refreezes. However, during years with a lot of melting and little snowfall, the water pools on the surface or flows into cracks in the ice. The meltwater enlarges these cracks until the ice shelf fractures and collapses into the sea. 

In 2002, the Larsen B ice shelf fractured following several years of warm summer temperatures. Larsen B’s collapse accelerated the flow of glaciers behind it, and billions of tons of ice were lost into the ocean. 

“If temperatures continue to rise at current rates, we may lose more Antarctic ice shelves in the coming decades,” said Dr. Gilbert. “Limiting warming will not just be good for Antarctica – preserving ice shelves means less global sea level rise, and that’s good for us all.”

The study is published in the journal Geophysical Research Letters.

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By Chrissy Sexton, Earth.com Staff Writer