Unlike the Arctic, which is an ocean surrounded by land, Antarctica is a continent surrounded by the ocean. This geography allows sea ice to spread over a larger area during the Southern Hemisphere’s winter. However, as the ice extends into warmer waters, much of it melts during the summer. Antarctic sea ice typically reaches its maximum extent in September, near the end of winter, 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 on September 14, 2026. Ice covered an estimated 17.59 million square kilometres (6.79 million square miles) on that date, marking the third-lowest maximum extent recorded by satellites.
Maps tracking Antarctic sea ice from 1990 to 2026 show its average concentration in September and the following February. White areas represent regions with the highest ice concentrations, while dark blue indicates open water. Scientists count areas with at least 15% ice concentration as ice-covered when calculating sea ice extent, the total area covered by these regions.
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Antarctic sea ice shifts from record highs to lows
Between 1979 and 2014, Antarctic sea ice extent increased by about 1% per decade. However, scientists remain uncertain whether this growth represented a long-term trend, as sea ice levels around Antarctica fluctuate significantly from year to year.
Between 1979 and 2014, Antarctic sea ice extent increased by about 1% per decade.
Satellite observations recorded three consecutive winter sea ice extent records between 2012 and 2014, even as Arctic sea ice declined sharply. The trend reversed in 2015, followed by substantial declines in Antarctic sea ice from 2016 onward. Although the region has experienced occasional recoveries, its sea ice coverage has generally remained below average.
In 2023, Antarctica recorded both its lowest annual minimum and lowest annual maximum sea ice extents in the satellite record. Scientists continue to monitor these changes to determine whether the decline signals a long-term shift or reflects natural year-to-year variability.
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How satellites track Antarctic sea ice
Scientists use satellites equipped with passive microwave sensors to measure the microwave energy naturally emitted by Earth's surface. Since sea ice emits a different microwave signal from open water, researchers can distinguish between the two in satellite observations.
Scientists use satellites equipped with passive microwave sensors to measure the microwave energy naturally emitted by Earth's surface
Microwaves can pass through clouds, allowing satellites to monitor sea ice regularly regardless of weather conditions. This makes the technology particularly useful for tracking changes across the remote Antarctic region.
The satellite record began in late 1978 with observations from NASA's Nimbus-7 satellite. Defense Meteorological Satellite Program (DMSP) satellites joined the effort in 1987, followed by NASA's Aqua satellite, which contributed observations between 2002 and 2011.
In 2025, scientists began using observations from Japan's Global Change Observation Mission-Water (GCOM-W) satellite, operated by the Japan Aerospace Exploration Agency, to continue monitoring Antarctic sea ice.