NASA (the U.S. space agency) published two Earth Observatory reports: the Arctic update and the Antarctic update. NSIDC (a U.S. center that tracks snow and ice) supplied the measurements used in the reports. Together, they show why the poles can have opposite seasonal headlines.

What happened

Arctic sea ice reached its yearly minimum on September 12, 2026. It covered an estimated 4.6 million square kilometers. That tied 2008, 2010, and 2025 for the tenth-lowest minimum in the satellite record.

Antarctic sea ice likely reached its yearly maximum on September 14. It covered an estimated 17.59 million square kilometers. That was the third-lowest maximum in the satellite record. The word likely matters. The seasonal peak is reported as an estimate, not a final measurement of every edge.

Why the seasons look opposite

Sea ice grows during each pole’s dark, cold season. It retreats during that pole’s warmer season. The Arctic usually reaches its maximum in March and its minimum in September. Antarctica usually reaches its maximum in September and its minimum in February.

Geography also matters. The Arctic is an ocean surrounded by land. Antarctica is a continent surrounded by ocean. Antarctic winter ice has more open water where it can spread. It also reaches warmer latitudes, so much of it melts during summer. The two annual numbers therefore cannot be compared as if the poles had the same setting.

Why it matters

The Arctic shows a clear long-term decline in the satellite record. Every summer from 2007 through 2026 ranked among the 20 lowest annual minimums. The March 2026 maximum also statistically tied 2025 for the lowest maximum in the record.

The ice that remains is younger and thinner. Multiyear ice, which survives at least one melt season, has declined. Weather still changes the number from year to year. However, NASA says natural variability alone cannot explain the decline across the record. Rising global temperatures also play a role.

Antarctica has followed a different pattern. Total Antarctic sea ice grew by about 1% per decade from 1979 through 2014. Scientists cautioned that year-to-year changes were large. The increase ended in 2015, and major declines began in 2016. There have been small rebounds, but coverage has generally stayed below normal.

What the data measure

Sea ice extent counts ocean areas with at least 15% ice concentration. Scientists use passive microwave sensors, which measure natural microwave energy from ice and open water. Microwaves can pass through clouds, allowing regular observations in many conditions.

The continuous record began in late 1978 with NASA’s Nimbus-7. Later observations came from DMSP satellites and NASA’s Aqua satellite. Since 2025, Japan’s GCOM-W satellite has also supplied observations. These records let scientists compare seasons across many decades.

What remains uncertain

Scientists do not yet know whether Antarctica’s decline since 2016 is a lasting trend or a statistical fluctuation. Both its record-low maximum and minimum occurred in 2023, followed by some rebounds. The Arctic summer minimum has also been relatively steady over the past decade. NASA scientists say increased cloud cover limited sunlight-driven melting during that period. A short plateau does not erase the longer decline.

What to watch next

The next step is to compare future annual highs and lows at both poles. Scientists will watch whether Antarctic low coverage repeats and whether young, thin Arctic ice remains common. Repeated satellite measurements can separate short-term weather from longer change. The 2026 results show why both poles need to be tracked together.