Antarctica’s sea ice has undergone a stunning reversal

Antarctic sea ice reached its third-lowest winter maximum in 2026, extending a remarkable decline that began after years of record-breaking growth. Scientists are investigating whether the dramatic reversal signals a long-term shift in Antarctica’s frozen landscape. Antarctica’s sea ice has undergone a stunning reversal.

Its maximum extent was the third lowest on record, adding to growing evidence of a dramatic shift in Antarctica’s frozen waters. Antarctica is surrounded by a vast ocean, giving its sea ice plenty of room to spread outward during the Southern Hemisphere’s winter. This differs from the Arctic, where an ocean basin is enclosed by surrounding land.

Although Antarctica’s geography allows winter sea ice to expand over enormous distances, it also pushes the ice into warmer latitudes, where melting becomes more likely during summer. As a result, Antarctic sea ice generally reaches its largest extent in September before shrinking to its annual minimum in February. According to NASA and the National Snow and Ice Data Center (NSIDC), Antarctic sea ice likely reached its annual maximum extent on September 14 (above).