The sea-ice extent peaked at 13.76 million square kilometers on March 13, 2026 -- approximately 0.03 million square kilometers below the 2025 record. The figure represents the annual maximum, defined as the point before ice extent begins its seasonal decline from April onward.
The monitoring program uses microwave radiometer data collected over more than 40 years, primarily from the Advanced Microwave Scanning Radiometer 2 (AMSR2) aboard JAXA's Global Change Observation Mission - Water satellite, known as SHIZUKU or GCOM-W. The dataset is archived and publicly accessible through the Arctic Data archive System (ADS), maintained as part of the Arctic Challenge for Sustainability III (ArCS III) project.
Throughout the winter of 2025-2026, sea-ice extent tracked persistently below the 2010s average. Analysis of the sea-ice edge on March 13 compared with the 2010s mean shows that two regions accounted for the shortfall: the Sea of Okhotsk and the Baffin Bay-Labrador Sea corridor between Greenland and Canada.
In both areas, temperatures from January through February 2026 remained above average, which constrained the southward expansion of ice. In the Sea of Okhotsk, the situation was compounded from mid-February to mid-March by prevailing easterly to southeasterly winds and temperatures higher than the same period in 2025. Ice extent in the Sea of Okhotsk began retreating after February 19, a development that researchers identified as a primary driver of the overall Arctic maximum falling short of previous years.
AMSR2 has now been in continuous operation for more than 13 years. JAXA is preparing the public release of data from its successor instrument, the Advanced Microwave Scanning Radiometer 3 (AMSR3), which is aboard the Global Observing SATellite for Greenhouse gases and Water cycle (GOSAT-GW), launched June 29, 2025. AMSR3 has been undergoing calibration and validation since launch, with routine operations having begun in October 2025. Data from AMSR3 are scheduled for public availability in summer 2026.
AMSR3 expands on AMSR2 capabilities by adding snowfall detection, enabling more integrated analyses of Arctic environmental conditions. Initial comparisons indicate that AMSR3 data quality is comparable to that of AMSR2.
Sea ice plays a central role in regulating the global climate system. Its variability has documented links to extreme weather patterns and marine ecosystem dynamics. The IPCC's Sixth Assessment Report identified the risk that Arctic sea-ice loss could reach thresholds that trigger broader, cascading effects across the climate system -- a concern that successive record lows reinforce.
NIPR, as a member institution of the Research Organization of Information and Systems (ROIS), leads Japan's polar observation infrastructure. The ArCS III project, launched in April 2025 and running through March 2030, coordinates Arctic research across natural sciences, social sciences, and the humanities, with JAXA and Hokkaido University serving as deputy representative institutions alongside JAMSTEC.
Related Links
National Institute of Polar Research
Beyond the Ice Age
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