This year, Arctic sea ice shrank to a minimum extent of 4.28 million square kilometers (1.65 million square miles). That’s about 1.94 million square kilometers (750,000 square miles) below the 1981 to 2010 end-of-summer average of 6.22 million square kilometers (2.4 million square miles)

Arctic sea ice retreated to near-historic lows in the Northern Hemisphere this summer, likely melting to its minimum extent for the year on September 11, 2024, according to researchers at NASA and the National Snow and Ice Data Center (NSIDC). The decline continues the decades-long trend of shrinking and thinning ice cover in the Arctic Ocean.

The amount of frozen seawater in the Arctic fluctuates during the year as the ice thaws and regrows between seasons. Scientists chart these swings to construct a picture of how the Arctic responds over time to rising air and sea temperatures and longer melting seasons. Over the past 46 years, satellites have observed persistent trends of more melting in the summer and less ice formation in the winter.

Tracking sea ice changes in real time has revealed wide-ranging impacts, from losses and changes in polar wildlife habitat to impacts on local communities in the Arctic and international trade routes.

This year, Arctic sea ice shrank to a minimum extent of 4.28 million square kilometers (1.65 million square miles), as shown on the map above. That’s about 1.94 million square kilometers (750,000 square miles) below the 1981 to 2010 end-of-summer average of 6.22 million square kilometers (2.4 million square miles). The difference in ice cover spans an area larger than the state of Alaska. Sea ice extent is defined as the total area of the ocean with at least 15 percent ice concentration.