Arctic warms at more than twice global rate in hottest year on record

Warming and freshening of Arctic waters can weaken ocean circulation systems that influence weather patterns across Europe and North America

The Arctic just experienced its hottest year on record, a milestone that scientists said was already changing weather systems far beyond the polar circle.

Surface air temperatures across the Arctic between October 2024 and September 2025 were the highest since at least 1900, according to the Arctic Report Card 2025, released this week by the US National Oceanic and Atmospheric Administration. It shows the region is now warming at more than twice the global average, with its 10 warmest years all coming in the past decade.

The warning came after a Copernicus report said this year was set to be the second or third warmest on record, potentially surpassed only by the record-breaking heat of 2024.

The earth is on track to complete the first three-year period when the average global temperature exceeded 1.5C above the 1850-1900 pre-industrial period when people started burning fossil fuels on an industrial scale.

“The Arctic is warming several times faster than Earth as a whole, reshaping the northern landscapes, ecosystems, and livelihoods of Arctic peoples,” the report’s executive summary said. “Also transforming are the roles the Arctic plays in the global climate, economic, and societal systems.”

The latest findings come as researchers document accelerating ice loss, record precipitation, warming oceans and widespread disruption to Arctic ecosystems – changes they warn are no longer confined to the far north.

Autumn 2024 was the warmest on record for the Arctic, according to the report, while winter 2025 ranked as the second warmest, driven by persistently high temperatures across much of the region. Precipitation between October 2024 and September 2025 reached a record high as well, with winter, spring and autumn each ranking among the five wettest since records began in 1950.

Surface air temperatures across the Arctic between October 2024 and September 2025 were the warmest recorded since 1900 (NOAA)

At sea, Arctic winter ice cover hit a new low. In March 2025, when sea ice would be expected to reach the annual maximum, the extent was the smallest in the 47-year satellite record. By September, summer sea ice had fallen to the 10th-lowest minimum ever observed, continuing a downward trend that scientists said was fundamentally altering the Arctic Ocean.

The oldest and thickest multi-year sea ice, once a defining feature of the Arctic, has declined by more than 95 per cent since the 1980s, with most remaining ice now confined to areas north of Greenland and the Canadian Arctic Archipelago.

In August, parts of the Arctic Ocean’s Atlantic sector recorded sea surface temperatures around 7C above the 1991–2020 average, an extreme anomaly that researchers linked to the growing influence of warmer Atlantic waters pushing northwards – a process known as “Atlantification”.

The report documents major biological changes linked to warmer, more open seas. Since 2003, phytoplankton productivity has increased by 80 per cent in the Eurasian Arctic, alongside significant rises in the Barents Sea and Hudson Bay. While increased productivity may sound positive, scientists warn it is reshaping food webs, altering fisheries and threatening Indigenous subsistence practices that depend on stable seasonal cycles.

On land, the impacts are equally stark. Glaciers in Arctic Scandinavia and Svalbard recorded their largest annual ice loss on record between 2023 and 2024.

The Greenland Ice Sheet lost an estimated 129 billion tonnes in 2025, continuing a long-term pattern that is contributing to global sea-level rise, even though the loss was below the longer-term annual average.

Photos show rapid loss of glaciers in the Arctic (Noaa)

“Ongoing glacier loss contributes to steadily rising global sea levels, threatening Arctic communities' water supplies, driving destructive floods and increasing landslide and tsunami hazards that endanger people, infrastructure, and coastline," the report said.

One of the most visible and alarming new phenomena highlighted in the report is the emergence of so-called “rusting rivers”. Across more than 200 watersheds in Arctic Alaska, thawing permafrost has released iron and other metals into rivers and streams, turning once-clear waters orange and increasing acidity and toxic metal concentrations. Scientists say this degradation threatens drinking water supplies, fish stocks and aquatic biodiversity in remote communities.

Researchers stress that what happens in the Arctic does not stay in the Arctic. The loss of reflective ice exposes darker ocean surfaces that absorb more heat, reinforcing warming through a feedback loop known as Arctic amplification. At the same time, warming and freshening of Arctic waters can weaken major ocean circulation systems that influence weather patterns across Europe and North America.

Some scientists also link rapid Arctic warming to changes in atmospheric circulation that may allow cold air to spill southwards more frequently, contributing to extreme winter weather in parts of Europe, Asia and North America.

The Arctic’s hydrological cycle is intensifying as well. More precipitation is falling as rain rather than snow, while June snow cover across the Arctic is now around half of what it was six decades ago, reducing the region’s ability to reflect solar radiation back into space.

The 2025 Arctic Report Card marks 20 years of continuous monitoring, offering what the US agency describes as an increasingly clear picture of a region undergoing rapid, systemic change. Scientists involved in the report emphasise that while not every year sets a new record, the long-term trajectory is unmistakable.

Despite improvements in observation networks, the agency warns that major gaps remain, particularly in remote areas, limiting scientists’ ability to track changes that affect water availability, infrastructure stability and food security.