The Arctic has experienced the hottest year since measurements have been taken regularly. The average temperature in the polar region has never been this high, according to the American National Oceanic and Atmospheric Administration (Noaa): a full 1.6 degrees Celsius above the 1991–2020 period.

"Never in recent times, and perhaps not for thousands of years"

The data, covering the twelve months between October 2024 and September 2025, are contained in the Arctic Report Card published by the US scientific agency, which draws on historical records dating back to 1900. The findings have been described as "alarming" by Tom Ballinger, one of the study's authors.

According to the scientist, speaking to the Afp news agency, this is a trend that is "apparently unprecedented in recent times and perhaps even over thousands of years". It is, after all, well established that the effects of global warming are markedly more pronounced in the Arctic region. This is a colossal problem, as it amplifies the melting of polar ice caps, fuelling rising sea levels which, in turn, will gradually submerge vast coastal areas around the world over the coming years — causing enormous economic damage and mass migration.

Growing risks for the Amoc ocean circulation system

That is not all: the melting of polar ice also contributes to altering circulation in the North Atlantic. The influx of less dense, less saline water prevents the feeding of the Amoc system, which stands for Atlantic meridional overturning circulation: a complex mechanism involving numerous deep and surface currents.

Zack Labe @ZLabe

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Our article for this year's Arctic Report Card was just published and can be found at arctic.noaa.gov/report-card/re… (#OpenAccess). Using data from OISSTv2.1, we document the latest trends and variability in summertime ocean temperatures (with a particular focus on regional anomalies).

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It can be compared to the boiler of an apartment building, with warm water being transported northward, losing heat at high latitudes, then returning as cold water toward the south. Amoc depends precisely on differences in water density, and plays an essential role in the climate balance of the entire world, but above all of the European continent.

In March, a record low for Arctic ice extent

This is why the pace of climate warming in the Arctic is so alarming. The year examined by Noaa in its report includes the warmest autumn on record, the second warmest winter and the third warmest summer. In particular, March 2025 saw an unprecedented retreat of the Arctic ice cap, which reached its lowest winter extent since satellite observations began.

On 22 March, the extent fell to just 14.33 million square kilometres, according to the US National Snow and Ice Data Center (Nsidc): the lowest value in over eighty years.

Rainfall and heat are turning the Arctic green — and Antarctica too

Furthermore, over the same October 2024–September 2025 period, precipitation reached record levels. The year ranks among the five wettest since 1950. This, combined with higher temperatures, has led to an increase in vegetation-covered areas. Exactly as has happened on the other side of the world, in Antarctica, where in the area between Cape Adams and the Eklund Islands, the portions covered in green are now fourteen times more extensive than they were in 1986.