Arctic sea ice covers the ocean with a layer of frozen seawater. It grows throughout the long polar winter, typically reaching its annual maximum in March, then melts during summer to reach its minimum extent in September. Although this seasonal cycle has continued for thousands of years, satellite records show that Arctic sea ice now covers less area at both its annual maximum and minimum than it did decades ago.

Arctic sea ice reached its 2026 minimum on September 12

Arctic sea ice reached its annual minimum extent on September 12, 2026, covering an estimated 4.6 million square kilometers (1.78 million square miles), according to NASA and the National Snow and Ice Data Center (NSIDC). The 2026 minimum tied with 2008, 2010, and 2025 as the 10th-lowest in the satellite record.

The map below pairs September sea ice near the annual minimum on the left with the following March sea ice near the annual maximum on the right. It shows the seasonal cycle for each year from 1990 through March 2026.

Satellite records show a long-term decline

Scientists have used satellites to continuously observe the annual growth and retreat of Arctic sea ice since late 1978. During that time, the overall area of sea ice has decreased, with the decline accelerating in the 2000s. The lowest value in the satellite record occurred in September 2012.

Every summer from 2007 through 2026 ranks among the 20 lowest summer minimums in the satellite record. Although September sea ice extent has been relatively stable in recent years, weather can cause substantial differences from one summer to the next. NASA scientists have noted that increased cloud cover over the past decade has limited sunlight and slowed summer melting in some years. Even so, recent summer minimums remain well below long-term averages.

Arctic ice is becoming younger and thinner

Beyond the North Pole, the remaining Arctic sea ice is generally younger and thinner. Multi-year ice that survives at least one summer melt season has declined, leaving the Arctic with mostly thin, first-year ice.

Winter sea ice is also shrinking. The March 2026 statistical maximum was aligned with the 2025 maximum, making it the lowest maximum in the satellite record. Learn more about the record-low Arctic sea ice maximum.

Climate change is driving the long-term trend

Natural cycles, including the Arctic Oscillation, can influence Arctic sea ice extent. However, natural variability alone cannot explain the decline observed throughout the satellite record. Natural fluctuations and rising global temperatures are working together to reduce Arctic sea ice.

Scientists project that essentially ice-free conditions in the Arctic could occur at least once before the middle of the 21st century, according to the Intergovernmental Panel on Climate Change.

How satellites measure Arctic sea ice

To estimate sea ice extent, scientists use satellites equipped with passive microwave sensors. These instruments measure the microwave energy naturally emitted by Earth. Sea ice emits more microwave energy than open water, allowing the two surfaces to be distinguished in satellite imagery.

Because microwaves can pass through clouds, satellites can monitor sea ice regularly regardless of weather conditions.

The satellite record began in 1978 with data collected by NASA’s Nimbus-7. It was followed by Defense Meteorological Satellite Program satellites launched in 1987 and NASA’s Aqua satellites from 2002 to 2011. Beginning in 2025, scientists started using observations from the Japan Aerospace Exploration Agency’s GCOM-W satellite.

The white circle at the center of each image is the “polar hole,” an area where satellite sensors have historically been unable to collect data. Sea ice estimates assume that this area is filled with ice.

Image by Michala Garrison using data from NASA Earth Observatory and the National Snow and Ice Data Center.

Sources

• IPCC (2021), Summary for Policymakers, in Climate Change in 2021: The Physical Science Basis. Accessed October 6, 2026.
• NASA Earth Data (October 2026), Sea Ice. Accessed October 6, 2026.
• NASA Earth Observatory (October 6, 2026), A World in Change: Arctic Sea Ice. Accessed October 6, 2026.
• NASA Earth Observatory (September 16, 2016), Sea Ice. Accessed October 6, 2026.
• NASA Earth Science (September 23, 2026), Arctic Sea Ice Reaches Annual Minimum Extent in 2026. Accessed October 6, 2026.
• National Snow and Ice Data Center (September 23, 2026), The Minimum Amount of Arctic Sea Ice Is Tied for the 10th Lowest Amount. Accessed October 6, 2026.
• National Snow and Ice Data Center (March 26, 2026), Arctic Sea Ice Hits Record Low Again. Accessed October 6, 2026.