‘Frightening’ winter sees Arctic sea ice hit record low for second year – Carbon Brief

Arctic sea ice has reached its peak this winter, and is at its lowest point in the satellite record going back nearly half a century.

Interim data from the US National Snow and Ice Center (NSIDC) show that sea ice extent peaked at 14.29 square kilometers (km2) on March 15.

This is slightly less than the previous record for annual maximum – set last year – but is considered a statistical tie, NSIDC said.

Annual size is an important marker in the cycle that shows how much sea ice grows in cold, dark winters, before melting in spring and summer to the annual minimum.

The combined record marks a “very alarming” winter for Arctic sea ice, Dr Zack Labe – Climate Central scientist – tells Carbon Brief.

And there is “horrible news”, Labe says, as the thickness of the ice is about to decrease – which means that the Arctic sea ice “enters the end of winter in one of the weakest countries in the satellite record”.

‘It’s unusually warm’

The past six months have seen “significant or near-significant declines in Arctic sea ice, as well as unusually warm conditions” across the region, says Dr Lettie Roach, a polar climate scientist at the Alfred Wegener Institute.

Roach tells Carbon Brief that “warmer air and ocean temperatures help melt ice and with less ice, the ocean absorbs more heat, which accelerates warming”.

The chart below shows the extent of Arctic sea ice in 2025 (dark blue) and 2026 (red) to date. For comparison, the chart shows two decades (dotted lines) as well as 2012 (middle blue), the year of the least summer ice cap.

In recent months there has been a “strong temperature difference” in the northern hemisphere, Roach continues:

In addition to large parts of the Arctic, temperatures were unusually warm in the western part of the US, southern Europe and eastern Eurasia, while northern Eurasia, northern Canada and the northeastern US were unusually cold.

This is associated with the jet stream, which is able to push cold Arctic air southward but brings warm air into the Arctic.”

These conditions have led to “bad” ice especially in areas such as the Sea of ​​Okhotsk, Baffin Bay, the Barents Sea and the Kara Sea, says Labe. He adds that “one of the areas with the most common sea ice is across the Bering Sea and east around Alaska”.

‘Long term decline’

This year’s winter peak is the latest in a “long-term downward trend we’ve seen” in Arctic sea ice since satellite monitoring began in the late 1970s, Roach said.

6 According to NSIDC, the 2026 area is 1.36m km2 less than the 1981-2010 average. That’s “twice the size of Texas”, the agency says.

Roach says Arctic sea ice is “not only shrinking in size,” it’s “thinner and more fragile than it used to be”.

Labe notes the “shocking news” that the sea ice “near the northern tip has had very low thickness for several months now”, adding:

In February, total Arctic sea ice was the second lowest on record.

Although there is “a lot of variation from year to year due to natural changes in the atmosphere and ocean”, this long-term decline is “mainly due to human-caused climate change”, says Roach.

Labe adds:

“Human-caused climate change is completely changing the polar environment and this is already having various consequences.”

The chart below shows the annual winter maxima (blue) and summer minima (red) since the satellite record began.

The chart highlights that the annual size “has shown a relatively steady decline over the past 40 years, with [previous] the latest decrease last year,” says Dr. Mika Rantanen, a researcher at the Finnish Meteorological Institute.

This is very different from the minimum of the year, where the record [low] is still there in 2012″, he tells Carbon Brief. This shows that the summer minimum “has more tendency” to rise and fall of different nature, he explains.

This is why it is “too early to tell” what the low winter peak means for the upcoming summer thaw season as “the climate can change quickly”, adds Labe:

But the winter of 2025-2026 is another clear indication of how fast the Arctic is changing.

‘Average’ Antarctica

On the other side of the Earth, the sea ice around Antarctica is melting in the southern hemisphere summer.

It reached its annual average of 2.58m km2 on February 26, the NSIDC said, making this year the 16th smallest on record.

For most of the summer, Antarctic sea ice has been “below average”, Dr Clare Eayrs, a postdoctoral researcher at the Korea Polar Research Institute (KOPRI), tells Carbon Brief. However, he continues:

That changed in January and February, when surface winds slowed the return.

These winds often “redistributed the ice rather than creating new ice in these areas”, notes Eayrs:

“This was enough to keep summer sea ice much closer to average than the previous four years… It’s a reminder that where a season begins doesn’t always mean where it ends.”

In recent years there has been a series of very low measurements in the sea ice around Antarctica.

Although it is “possible” that climate change is affecting Antarctic sea ice, scientists “remain uncertain about the extent and precise mechanisms involved”, says Eayrs:

This uncertainty itself is an important part of the story.

However, a recent study points to a recent “structural change” in the Antarctic sea ice system, Eayrs notes. This is characterized by a greater persistence of low sea ice and “less tendency for the system to return to its earlier state”.

In other words, Eayrs says, “when the sea ice goes down abnormally low, it doesn’t go back as fast as before”.