•NASA and the National Snow and Ice Data Center (NSIDC) report that Antarctic sea ice reached its annual maximum on September 14, 2026, when the ice cover reached approximately 17.59 million square kilometers (6.79 million square miles). The value is the third lowest maximum on record since satellite observations began, according to a NASA Earth Observatory report. Antarctic sea ice typically reaches its maximum in September, at the end of the Southern Hemisphere’s winter, and reaches its minimum in February. Unlike the Arctic, which is an ocean basin surrounded by land, Antarctica is a large landmass surrounded by ocean; this geographical feature allows the sea ice to expand more during the winter and melt more during the summer.
Current data show that total Antarctic sea ice has increased by about 1 percent per year from 1979 to 2014. But it is unclear whether this increase is a sign of a meaningful change; because the ice cover around Antarctica varies greatly from year to year. In 2012-2014, three consecutive years in which satellites observed new records in the maximum winter sea ice, occurred during a period when Arctic ice sheets were in a steep decline.
To determine the ice area, scientists rely on satellites equipped with passive microwave sensors that measure the microwave energy naturally emitted by the Earth. Sea ice emits more of this energy than open water, so it stands out in microwave images. Microwaves pass through clouds, so satellites can observe sea ice regularly, regardless of weather conditions. The records began with data collected by NASA’s Nimbus-7 satellite in late 1978; then the Defense Meteorological Satellite Program (DMSP) satellites from 1987, and NASA’s Aqua satellite from 2002 to 2011. In 2025, scientists began using observations from the Japan Aerospace Exploration Agency’s GCOM-W satellite.
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