The total area of the Arctic Ocean that was at least 15% ice covered each September from 1979–2020. Since 1980, the amount of ice that survives the summer has declined by 13.1 percent per decade. Data from the National Snow and Ice Data Center (NSIDC).
Sea ice concentration on September 16, 2021, the day of the minimum, compared to the 1981-2010 median extent (gold line). Over the past 4 decades, the ocean area covered by ice in September has declined by 40 percent. Data from NSIDC.