Global sea levels are rising as oceans warm and continental ice sheets melt.

This will change the way we live in the future, but there are deep uncertainties about how fast sea levels will rise as the Earth gets warmer.

Waves crashing against an iceberg — Ocean swells can flex ice shelves making them more prone to break off in massive ‘calving’ events. Picture: Getty Images

The Antarctic Ice Sheet is the thick layer of ice that sits on top of Antarctica and holds enough freshwater to raise sea levels by over 50 metres. It has the greatest potential to push future sea levels far above current best estimates.

However, transporting the frozen water from the ice sheet to the ocean is usually slow – glacial, you might say.

This slow process involves the Antarctic Ice Sheet flowing towards the coastline through a network of glaciers. At the coastline, the glaciers flow onto the ocean surface, creating floating platforms known as ice shelves that are typically hundreds of metres thick and can be the size of countries.

The ice is then lost to the ocean through gradual melting of the ice shelves from below and icebergs ‘calving’ away from their ocean-facing boundaries.

A graphic of the Antarctic Circumpolar Current

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In a stable climate, the Antarctic Ice Sheet has ‘mass balance’, with gains from snowfall over Antarctica equalling loss from ice shelves.

But warming temperatures are forcing ice shelves to melt more rapidly and calve more frequently.

Although this does not directly increase sea levels (as the ice shelves are already floating on the ocean), it reduces the ability of ice shelves to push back against glacial flow into the ocean – which does raise sea levels.

This means the fate of ice shelves is a key factor to predict future sea levels.

Over the past few decades, satellite images have allowed us to witness alarming calving events, where huge chunks of ice shelves broke off (calved) into a collection of icebergs.

The 2025 Antarctic sea ice minimum was the equal second lowest on record. Video: NASA / YouTube

However, we now appear to be in a new era of sea ice retreating at an unprecedented rate all around Antarctica.

Our work suggests this will put further pressure on ice shelves that have already been thinned and weakened.

In fact, it could lead to more large-scale calving events, with profound implications for the future of global sea levels.

This article was first published on Pursuit. Read the original article.

Dr

Luke Bennetts

Professor of Applied Mathematics

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