Arctic sea ice shrinks to record winter low as Earth heats up

BOULDER, Colorado – The Arctic Ocean likely had the smallest winter ice cover in 47 years of satellite records this season, with just 14.32 million sq km of sea ice covering the region at its peak on March 22.

That is 1.32 sq km less than the median coverage at other March peaks between 1981 and 2010, according to the National Snow & Ice Data Centre at the University of Colorado at Boulder –a reduction equivalent to an area larger than Peru.

Arctic winter ice typically reaches its broadest expanse in March, after which, it begins a slow melt over the spring and summer months, shrinking to its smallest area, or minimum extent, in September.

The previous record winter low occurred in 2017. 

The new record is still a preliminary finding but is unlikely to change, said Professor Mark Serreze, the centre’s director. 

2024 was the hottest year on record,

 and the loss of Arctic ice threatens to accelerate feedback loops involved in climate change.

Warmer, darker and more open ocean waters absorb solar energy that would otherwise be reflected by ice, trapping more heat. 

“Every year, we’re increasing the amount of heat that is stored in the Arctic Ocean,” said Professor Penny Vlahos, a climate scientist at the University of Connecticut.

Since global weather patterns are driven by temperature differences between the planet’s higher and lower latitudes, a faster-warming Arctic could lead to more unpredictable weather, Prof Vlahos said. 

“The analogy I use is that the Arctic is the ice in our cooler,” she said.

“When the ice is gone in your cooler, you no longer have refrigeration and that’s exactly what’s happening to us. That ice in the Arctic and the Antarctic is the buffer in our system, and when you lose that, you are subject to much more extreme weather.” 

The dwindling of sea ice also has geopolitical and security ramifications, as it opens up the Arctic to more shipping and potential military uses.

Russian President Vladimir Putin said on March 27 that he expects cargo shipments via the Northern Sea Route to reach 70 million to 100 million tons by 2030, compared with almost 38 million tons in 2024. 

Prof Serreze said levels of winter ice this low could compound the decline of the region’s summer sea ice, which is expected to disappear as early as the next decade.  

“We used to think starting off on a bad footing” ahead of the Arctic summer “didn’t necessarily mean a very low September sea ice extent”, said Prof Serreze.

More snowfall in the spring, for example, could help the resilience of the summer ice cover.

But now, he said, “we’re thinking, maybe it does. That’s because it’s so much warmer and the ice is so much thinner than it used to be”.

Each year, as the Arctic winter sea ice builds to a peak, sea ice on the opposite pole shrinks during the Southern Hemisphere’s summer.

Antarctic sea ice covered just 1.98 million sq km at its lowest point for the year, according to data released by NSIDC earlier in March.

That figure was the second-lowest on record, tying with 2022 and 2024, and 30 per cent lower than the amount of ice that was typical in the region before 2010. BLOOMBERG