Scientists thought Arctic winter ice was stabilizing. They were wrong

For years, it looked like Arctic winter sea ice had stopped shrinking. Two record-breaking winters, one year after the other, just proved it never did.

For much of the early 2020s, something appeared to have shifted in the Arctic. The steady, decades-long decline in winter sea ice seemed to be losing momentum, prompting some scientists to wonder whether wintertime ice might have found a temporary floor. It was a tantalizing, if carefully hedged, idea.

For much of the early 2020s, something appeared to have shifted in the Arctic: the steady, decades-long decline in winter sea ice seemed to be losing momentum. Some scientists cautiously raised the possibility that wintertime ice might have found a temporary floor. It was an intriguing, if carefully hedged, idea. Now, a new study published in PNAS by researchers at the University of Southampton and the National Oceanography Centre has definitively closed that chapter. The pause was never a genuine recovery.

Two consecutive record-breaking winters in 2025 and 2026 have restored the long-term downward trend, and reframed what that earlier lull actually meant.

In August 2025, a study in Geophysical Research Letters, led by researchers at the University of Exeter, confirmed that Arctic sea ice loss had slowed significantly over the previous two decades. Yet, they also found that this kind of multi-decade pause could happen naturally, even as the climate continues to warm. The slowdown was real. The idea that it signaled genuine recovery was not.

What came next seemed to definitively confirm that hypothesis. Between the winter of 2024 and the winter of 2025, Arctic sea ice during its peak months fell by 5.8% — the largest single-year winter drop in 47 years of satellite records. On March 22, 2025, it hit the lowest winter maximum ever recorded. The next year, the second lowest was hit. Two winters at or near all-time records, back-to-back, were enough to overwhelm the years of apparent stabilization and restore the long-term decline in full. 

“What looked like a pause in the early 2020s now appears to have been a temporary slowdown within a longer-term decline associated with global warming. This sharp drop changes the way we interpret recent Arctic winter sea ice change,” wrote Dr. Duo Chan, lead author of the study from the University of Southampton.

Key findings

• The largest single-winter drop on record: Arctic sea ice fell 5.8% in a single winter, marking the biggest year-to-year drop in 47 years of satellite records. The March 2025 peak beat the previous record low by an area roughly the size of South Carolina.
• The pause was always temporary: The earlier Exeter study found that sea ice loss had slowed by 55–63% relative to the long-term average, but it was consistent with natural climate swings rather than a genuine reversal. The winters of 2025 and 2026 proved it.
• Less ice, not just thinner coverage: While the extent of ice in 2026 recovered slightly from 2025’s record low, total Arctic sea ice volume in March 2026 hit its lowest point ever — roughly 15% below March 2024. Less volume means ice that melts faster in summer and insulates less in winter. That number may matter more than the area figures.
• Winter ice does something summer ice cannot: Winter ice acts as a lid between the relatively warm Arctic Ocean and the cold air above. Without it, heat escapes upward,  disrupting weather patterns across the Northern Hemisphere. The consequences of losing winter ice are felt far beyond the Arctic.
• Models say the new baseline is here to stay: The researchers used climate model simulations to identify years in which a drop similar to 2025 had occurred under comparable conditions. What typically followed was not a rebound; ice fluctuated around a new, lower level, and they believe a return to early 2020s conditions looks unlikely.
• More melting pauses will come, and the lesson is how to read them: The natural variability that produced the early 2020s slowdown hasn’t gone away. In a warmer, more volatile Arctic, the same forces will temporarily mask the trend again. But now there’s a record that includes 2025 and 2026, making it much harder to mistake a short-term fluctuation for a genuine recovery.

“Short-term recoveries can temporarily obscure the longer-term direction of Arctic sea ice change. The low winter sea ice extents in 2025 and 2026 clearly show that Arctic sea ice loss has not stopped — it is continuing in a warming climate,” explained Dr. Chan.

For Arctic communities whose livelihoods, food systems, and cultures are built around sea ice, these findings carry an urgency no data point can fully capture. Thinning winter ice means altered hunting seasons, less stable travel routes, and faster coastal erosion in places already watching their shorelines disappear. It means shipping lanes open when they shouldn’t, and frozen when a warming world’s economics demands they are not.