The Arctic could lose a million km² more winter ice than climate models calculated
That's an area about twice the size of Spain. The Barents, Greenland and Labrador seas would be hit hardest, with the ice edge retreating north.
The ice covering the Arctic Ocean in winter could shrink in the coming decades by about a million square kilometres more than climate models calculated, roughly twice the area of Spain. That is the conclusion of a study by the University of Cambridge (UK) and CIMAT (Mexico), published in Nature Geoscience.
Looking at the past to correct the future
Between 5,000 and 7,000 years ago, small changes in Earth’s orbit made the Arctic warmer. The authors used that period as a test:
- They searched 46 seafloor sediment records for a molecule made by algae that live in sea ice. That let them estimate how much ice there was back then.
- They checked how well 27 climate models reproduced that past, and gave more weight to those that got it right.
The result: the models overestimated winter ice, even for recent decades. With the correction, uncertainty drops by up to 85%.
Where it will show most
The Barents, Greenland and Labrador seas are the most exposed: the ice edge could retreat up to 5.5 degrees of latitude northward.
Why winter ice matters
Winter ice regulates how much heat and moisture pass from the ocean to the air. Its loss has been linked to colder winters and heavy snowfall in northern Europe and North America. In March 2025, the winter ice maximum was the lowest in the modern record.
The authors point to possible effects on Mediterranean rainfall and Greenland snow, but warn these are leads, not firm forecasts.
At the other pole, ice is also surprising scientists: Antarctica’s tallest ice cliffs collapse faster than expected.
Sources and references
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