Arctic sea ice reached its annual minimum on September 12 at an estimated 4.6 million square kilometers, or 1.78 million square miles. NASA’s October 7 review says the measurement ties the minimums recorded in 2008, 2010 and 2025 for tenth-lowest since continuous satellite monitoring began.

Every summer from 2007 through 2026 now ranks among the 20 lowest minimum extents in the record. Although September coverage has varied less dramatically during the past decade, NASA notes that it remains well below the longer-term average and that weather can strongly influence any single melt season.

The composition of the ice has also changed. Multiyear ice has declined, leaving more of the Arctic covered by thinner first-year ice, while the March 2026 winter maximum statistically tied the 2025 maximum for the lowest on record.

Scientists build the long record with passive microwave instruments that distinguish ice from open water and can observe through clouds. Natural cycles affect year-to-year conditions, but NASA’s review says the decline over the full satellite era cannot be explained by natural variability alone.