Arctic sea ice reached its annual minimum extent on Sept. 12, according to NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder. The ice covered an estimated 1.78 million square miles (4.6 million square kilometers), tying 2008, 2010, and 2025 for the 10th-lowest minimum in the satellite record.
The 2026 minimum is consistent with patterns observed in the satellite record. The past 20 years, from 2007 through 2026, have produced the 20 lowest annual Arctic sea ice minimum extents observed since continuous satellite measurements began in late 1978.
Arctic sea ice grows during the dark, cold autumn and winter and retreats as temperatures rise during spring and summer, typically reaching its lowest extent in September. Weather conditions can cause substantial differences in the amount of ice that melts from one summer to another.
Over the last decade, for example, increased cloud cover has prevented solar radiation from further accelerating the melt of sea ice, according to Linette Boisvert, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
That has contributed to relatively stable September sea ice extent in recent years. “We’ve plateaued, but we’re still low relative to the earlier part of the record,” said Walt Meier, a senior research scientist at NSIDC.
Antarctic sea ice extent approaches annual maximum
At the opposite end of the planet, Antarctic sea ice is approaching its annual maximum following a fluctuation during August.
Sea ice around Antarctica declined by roughly 116,000 square miles (300,000 square kilometers) over a six-day period before resuming its seasonal growth. Meier said the decline appeared to be associated with weather conditions that pushed and compacted the thin, mobile ice near its outer edge.
“Those types of things happen all the time,” Meier said. “But the magnitude of it certainly is unusual.”
Antarctic sea ice varies more from year to year than Arctic sea ice because, in contrast to the Arctic, it is not surrounded by land and can respond more freely to changing wind and weather conditions. But Antarctic sea ice extent at its annual maximum has generally been lower in recent years. Because of this large year-to-year variability, Boisvert and Meier remain cautious about characterizing the change as a long-term trend.
Scientists have tracked polar sea ice from space for nearly five decades. During that time, NASA and the National Oceanic and Atmospheric Administration (NOAA) used a series of satellite instruments to maintain a continuous sea ice record, beginning with NASA’s Nimbus-7 satellite, which began observations in October 1978. The record continued with instruments aboard Defense Meteorological Satellite Program satellites beginning in 1987 and NASA’s Aqua satellite from 2002 to 2011. Today, scientists continue the record using data from the Advanced Microwave Scanning Radiometer 2 (AMSR2), launched in 2012 aboard JAXA’s (Japan Aerospace Exploration Agency) GCOM-W satellite.
Antarctic sea ice typically reaches its annual maximum in late September or early October. NASA and NSIDC will announce the 2026 maximum after scientists confirm that seasonal ice growth has ended.
Media contact: Elizabeth Vlock
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Source: science.nasa.gov