Arctic sea ice reached its 2026 annual minimum on September 12, covering about 4.6 million square kilometers (1.78 million square miles), a total that ties 2008, 2010 and 2025 for the 10th-lowest minimum in the satellite record. The measurement is more than a month old, and it was already settled when NASA and the National Snow and Ice Data Center announced it on September 23. NASA’s Earth Observatory revisited the minimum on October 7.
The September 12 measurement from NASA and NSIDC
The date is the point at which Arctic ice stopped shrinking for the year: after the March maximum, the ice melts through the summer until it reaches a low point in mid-September, then begins to refreeze. Both the figure and the date are therefore a snapshot of one day, not a seasonal average, and the day belongs to September, not to the weeks of reporting that followed.
The announcement came from NASA and NSIDC at the University of Colorado Boulder. In its September 23 NASA release, written by senior science writer James Riordon, the agencies said the ice “reached its annual minimum extent on Sept. 12” at about 1.78 million square miles. NSIDC’s own analysis, posted in its Sea Ice Today series, used the same date and 4.60 million square kilometers, and described the minimum as sharing “the tenth lowest spot in the nearly 48-year satellite record” with 2008, 2010 and 2025.
The ranking language matters. It is a tie, not a single position, and it is a satellite-era rank: continuous satellite measurements began in late 1978, so “on record” here means that span of roughly 48 years. NASA’s October 7 Earth Observatory entry, credited to Michala Garrison, restates the figure and adds the context that every summer from 2007 through 2026 ranks among the 20 lowest minimums. The lowest minimum occurred in September 2012, and NASA adds that September extent has been relatively steady lately even as the summer minimum remains well below the long-term average.
A plateau that has not recovered
The 10th-lowest tie sounds like a middle ranking, but the 20 lowest minimums in the satellite record are the past 20 years. Walt Meier, a senior research scientist at NSIDC, said in the NASA release that the ice has plateaued but remains “still low relative to the earlier part of the record.” The long-term decline steepened in the 2000s, according to NASA, which is why the recent years cluster together near the bottom of the ranking.
The October 7 entry carries the same ranking, unchanged since September 23.
Linette Boisvert, a sea ice scientist at NASA’s Goddard Space Flight Center, attributed part of the recent flattening to weather. She said increased cloud cover over the last decade has kept solar radiation from accelerating melt further. The Earth Observatory’s World of Change series adds that the ice is younger and thinner than it was, with multiyear ice declining and first-year ice now dominating, and that the March 2026 maximum statistically tied 2025 for the lowest in the satellite record.
Dataset differences behind the tenth-place tie
A tied tenth place is also a product of how close the recent minimums sit to each other. The UK Met Office’s briefing of September 21, written by Alex West and Ed Blockley, used a different dataset, the OSI SAF Sea Ice Index, and put the same September 12 minimum at 5.06 million square kilometers, 14th lowest since 1979, and 1.51 million square kilometers below the 1981 to 2010 average. By that dataset’s map, extent was well below average across the Arctic Ocean, with only small areas in the Greenland Sea, the eastern Beaufort Sea and the central Laptev Sea near average, and the minimum sat 0.75 million square kilometers above the long-term linear trend. The briefing notes that the NSIDC Sea Ice Index ranks 2026 as 11th lowest, 1.63 million square kilometers below average.
The Met Office attributes the spread to several recent minimums being very close together and to the sensitivity of a minimum to how satellite microwave data are converted into ice coverage. The satellite record itself has changed hands over time. NASA’s account says observations come from passive microwave sensors that see through clouds, and that scientists began using JAXA’s GCOM-W satellite in 2025, after earlier records drew on Nimbus-7, the Defense Meteorological Satellite Program and NASA’s Aqua.
NSIDC’s October 7 analysis noted that the freeze-up after the minimum has been rapid. NASA and NSIDC have yet to report the Antarctic maximum for 2026, which the release said they will announce after scientists confirm seasonal growth has ended; Antarctic ice dropped by about 116,000 square miles over six days in August before resuming growth, and Meier said “those types of things happen all the time,” though “the magnitude of it certainly is unusual.” Boisvert and Meier cautioned against reading the lower recent Antarctic maximums as a long-term trend, because Antarctic ice varies more from year to year than Arctic ice does.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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