Arctic winter sea ice sharply declines, study finds

A new analysis by scientists at the University of Southampton and the UK National Oceanography Centre, published in the Proceedings of the U.S. National Academy of Sciences, shows that the brief slowdown in Arctic winter sea‑ice loss observed in the early 2020s has ended. Incorporating exceptionally low ice extents from the winters of 2025 and early 2026, the study finds a 5.8 % drop in maximum winter ice cover between 2024 and 2025 – the largest year‑on‑year decline recorded since satellite monitoring began in 1978. The 2025 minimum was historic, and the 2026 extent, while slightly higher, remained the second‑lowest on record.

The researchers conclude that the long‑term trend of diminishing winter sea ice has resumed, reinforcing its link to global warming. Reduced ice weakens the barrier between relatively warm Arctic Ocean waters and the cold winter atmosphere, allowing more heat and moisture to enter the atmosphere. This can alter pressure systems, storm development and large‑scale atmospheric circulation, potentially affecting weather farther south.

The findings underscore Arctic sea ice as a key climate indicator and suggest that the apparent ‘pause’ in ice loss was only a temporary slowdown within a longer‑term decline.