Arctic sea ice hit twice as hard when storms arrive in clusters: study

Arctic storms that pass quickly, one after the other, cause about twice the reduction in sea ice cover as single storms, says a new study published this month.

The storm phenomenon, known as cyclone clustering, also affects sea ice for about two-and-a-half times longer than isolated storm events, the researchers found.

To do the study, published this month in the journal Nature Communications, researchers examined satellite and weather data from 1979 to 2024, to track how sea ice changed when hit by successive clusters.

During cold Arctic winters, cyclones can break up the ice cover into floes that drift and collide with each other. The polar cold, however, usually refreezes the gaps between them within a few days.

“We could be entering a self-enforcing feedback loop: the weaker the sea ice becomes, the more cyclone clusters can reduce its extent, which in turn weakens the sea ice,” Lars Aue, lead author of the study from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), said in a statement.

Impacts continue outside of winter

But even in warmer months, when cyclone clusters are generally weaker, they can still have a big local impact on the ice.

Their force, even then, can pushing floes northwards and carring warmer air with them that further contributes to melting.

“Furthermore, they can also transport warmer seawater from deeper layers to the surface, causing the upper water masses to warm up,” AWI said in news release about the research. “Over the last two decades, cyclones have thus contributed to ice loss, particularly towards the end of the melting season.”

And as sea ice becomes thinner and more mobile as the climate warms, the impact of cyclone clusers could become even more pronounced.

“We could be entering a self-enforcing feedback loop: the weaker the sea ice becomes, the more cyclone clusters can reduce its extent, which in turn weakens the sea ice,” Aue said.

The study’s findings can help contribute towards future sea ice predictions, especially important for Arctc communities where sea ice as buffer against waves, and where ice retreat could leave coastal communites more vulnerable to storms, Aue said.

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