Arctic sea ice appears to have reached its maximum extent on March 21, 2021, tying for seventh lowest in the 43-year satellite record. NSIDC will post a detailed analysis of the 2020 to 2021 winter sea ice conditions in our regular monthly post in early April.
Overview of conditions
On March 21, 2021, Arctic sea ice likely reached its maximum extent for the year, at 14.77 million square kilometers (5.70 million square miles), tying for the seventh lowest extent in the satellite record with 2007. This year’s maximum extent is 870,000 square kilometers (336,000 square miles) below the 1981 to 2010 average maximum of 15.64 million square kilometers (6.04 million square miles) and 360,000 square kilometers (139,000 square miles) above the lowest maximum of 14.41 million square kilometers (5.56 million square miles) set on March 7, 2017. Prior to 2019, the four lowest maximum extents occurred from 2015 to 2018.
The date of the maximum this year, March 21, was nine days later than the 1981 to 2010 median date of March 12.
Table 1. Ten lowest maximum Arctic sea ice extents (satellite record, 1979 to present)
| Rank | Year | In millions of square kilometers | In millions of square miles | Date |
|---|---|---|---|---|
| 1 | 2017 | 14.41 | 5.56 | March 7 |
| 2 | 2018 | 14.47 | 5.59 | March 17 |
| 3 | 2016 2015 | 14.51 14.52 | 5.60 5.61 | March 23 February 25 |
| 5 | 2011 2006 | 14.67 14.68 | 5.66 5.67 | March 9 March 12 |
| 7 | 2007 2021 | 14.77 14.77 | 5.70 5.70 | March 12 March 21 |
| 9 | 2019 | 14.82 | 5.72 | March 13 |
| 10 | 2005 | 14.95 | 5.77 | March 12 |
For the Arctic maximum, which typically occurs in March, the uncertainty range is ~34,000 square kilometers (13,000 square miles), meaning that extents within this range must be considered effectively equal.
Final analysis pending
Please note this is a preliminary announcement of the sea ice maximum. At the beginning of April, NSIDC scientists will release a full analysis of winter conditions in the Arctic, along with monthly data for March.