NOAA's National Centers for Environmental Information
Sea Ice Extent
The sea ice extent data for the Arctic and Antarctic are provided by the National Snow and Ice Data Center (NSIDC) and are measured from passive microwave instruments onboard NOAA Satellites. The sea ice extent period of record is from 1979–2021 for a total of 43 years.
| July 2021 | Sea Ice Extent | Anomaly 1991-2020 | Trend per decade | Rank (43 years) | Record | ||||
|---|---|---|---|---|---|---|---|---|---|
| million km² | million mi² | Year(s) | million km² | million mi² | |||||
| Northern Hemisphere | 7.65 | 2.95 | -12.57% | -7.89% | Largest | 41st | 1983 | 10.57 | 4.08 |
| Smallest | 3rd | 2020 | 7.29 | 2.81 | |||||
| Southern Hemisphere | 16.45 | 6.35 | +2.36% | +0.56% | Largest | 6th | 2014 | 17.11 | 6.61 |
| Smallest | 38th | 2017,2019 | 15.30 | 5.91 | |||||
| Globe | 24.10 | 9.31 | -2.90% | -2.42% | Largest | 35th | 1979 | 26.83 | 10.36 |
| Smallest | 9th | 2019 | 22.89 | 8.84 | |||||
Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2021 (43 years)
The Arctic sea ice extent for July 2021 was the fourth smallest July sea ice extent on record at 1.78 million square km (687,000 square miles) below the 1981–2010 average. Only Julys of 2012, 2019, and 2020 had a smaller sea ice extent in July. July 2021 also marked the 21st consecutive July with below-average sea ice extent. According to the NSIDC, the sea ice extent during July 4–9, 2021 was the lowest extent on record for this time of year; however, afterwards, the rate of sea ice extent loss slowed.
The Antarctic sea ice extent was above average. The July 2021 Antarctic sea ice extent of 16.38 million square km (6.32 million square miles) was 420,000 square km (160,000 square miles) above average. This was the largest July sea ice extent since 2015 and the eighth largest July sea ice extent in the 43-year record. The sea ice extent in the Antarctic grew faster than average during the month. Sea ice was above average across parts of the northeastern Ross Sea and in the Southern Ocean south of Africa.