Sea ice in the Arctic has smallest extent since 1979

Spring is also coming to the Arctic. This means that the winter growth of sea ice ends – and thus a record winter.

However, this is a negative record: never before has there been so little winter ice as on March 21, 2025, since the Arctic sea ice has been continuously recorded by satellites. This has been the case since 1979. To date, 2017 was the year with the lowest sea ice extent. This negative record has now been broken, according to the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI).

On March 21, only 14.45 million square kilometers were covered by ice. The average value in March was 14.21 million square kilometers, as the sea ice portal of the AWI and the University of Bremen shows. This is 1.13 million square kilometers less than the average for the observation years 1981 to 2010, which is roughly equivalent to the area of Germany and France combined.

Ice drift as a reason

An important reason for the low extent of sea ice in March is ice drift: satellite data from October 2024 to March 2025 show that strong offshore winds have driven the sea ice away from the coast of Russia towards the central Arctic due to the position of low-pressure areas. “In colder regions such as the Laptev and Kara Seas, this led to an above-average formation of new ice, while in the warmer Barents Sea a northward shift of the ice edge was observed,” said Thomas Krumpen, sea ice physicist at the AWI.

However, the cause of the decline is the comparatively high air temperatures last winter. Temperatures in March were minus 10 degrees Celsius in many areas. That was enough for the ocean to freeze into sea ice. However, it was up to 9 degrees Celsius warmer than the long-term average for the years 1981 to 2010.

The temperatures are rising

“Some of our ice buoys, which drift through the Arctic and transmit their data by satellite, measured temperatures of just minus 5 degrees Celsius above the ice at times in January and February 2025,” reported Krumpen. “In February, the temperature in some regions was even up to 16 degrees Celsius above the previous average values, as the map of temperature anomalies shows. This will have reduced ice growth in some regions, an effect that is also visible in model and satellite data.”

The sea ice in the Arctic reaches its maximum winter extent in February and March each year. As temperatures rise, it melts until the summer minimum in September. Temperatures then fall again and new ice forms.

The development in the first three months of the year makes it possible to estimate how the sea ice in the Arctic could change by the end of the summer. “Some indications point to a low summer sea ice extent,” said Krumpen. “In recent months, for example, we have observed that an above-average amount of old and thick sea ice has left the Arctic through the Fram Strait – presumably caused by unusual drift constellations in recent years.”

(wpl)