28 Apr 2026

A decades-long study of oceanographic data provides the first evidence that deep-ocean heat has moved closer to Antarctica, threatening the fragile ice shelves that fringe the continent.

The study, led by the University of Cambridge with collaborators from the University of California and published in the journal Communications Earth & Environment, compiled long-term ocean measurements collected by ships and robotic floating devices to show that a warm mass called circumpolar deep water has expanded and shifted toward the Antarctic continental shelf over the past 20 years.

Previously, scientists hadn’t had enough ocean observations to detect the warming trend. “It’s concerning because this warm water can flow beneath Antarctic ice shelves, melting them from below and destabilising them,” said Joshua Lanham, lead author of the study from Cambridge's Department of Earth Sciences.

Ice shelves play an important role in holding back Antarctica’s inland ice sheets and glaciers, which collectively hold enough freshwater to raise sea level by about 58 metres.

It’s the first time that scientists have observed the shift in deep-ocean heat throughout the Southern Ocean, said Lanham. “It’s something that had been predicted by climate models due to global warming, but we hadn’t seen it in data.”

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