Analysis - Sea Ice Today

Antarctic sets a record low maximum by wide margin

MONDAY, SEPTEMBER 25, 2023

On September 10, Antarctic sea ice likely reached its annual maximum extent of 16.96 million square kilometers (6.55 million square miles). This is the lowest sea ice maximum in the 1979 to 2023 sea ice record by a wide margin.

Please note that this is a preliminary announcement. Changing winds or late-season growth could still increase the Antarctic ice extent. NSIDC scientists will release a full analysis of the Antarctic and Arctic September conditions in early October.

Overview of conditions

On September 10, 2023, sea ice in the Antarctic reached an annual maximum extent of 16.96 million square kilometers (6.55 million square miles), setting a record low maximum in the satellite record that began in 1979 (Figure 1). This year’s maximum is 1.03 million square kilometers (398,000 square miles) below the previous record low set in 1986. It is also 1.75 million square kilometers below (676,000 square miles) below the 1981 to 2010 average Antarctic maximum extent. Sea ice extent is markedly below average north of Queen Maud Land and west of the Antarctic Peninsula. Other low areas include the Indian Ocean and Ross Sea. Extent is above average stretching out of the Amundsen Sea.

The Antarctic maximum extent is one of the earliest on record, having reached it 13 days earlier than the 1981 to 2010 median date of September 23. The interquartile range for the date of the Antarctic maximum is September 18 to September 30.

Figure 1. Antarctic sea ice extent for September 10 2023, was 16.96 million square kilometers (6.55 million square miles). The orange line shows the 1981 to 2010 average extent for that day. Sea Ice Index data. About the data — Credit: National Snow and Ice Data Center

Conditions in context

This year marks a significant record low maximum in Antarctic sea ice extent (Figure 2). Since early April 2023, sea ice maintained record low ice growth. From early to mid-August, growth slowed considerably, maintaining a difference of nearly 1.5 million square kilometers (579,000 square miles) between 2023 and 1986, the second lowest year on satellite record. After that period, ice growth quickened and narrowed the gap to about 1 million square kilometers (386,000 square miles). This is the first time that sea ice extent has not surpassed 17 million square kilometers (6.56 million square miles), falling more than one million square kilometers below the previous record low maximum extent set in 1986.

While weather conditions like winds and temperature control much of the day-to-day variations in ice extent, the long-term downward trend is a topic of much debate. The overall, trend in the maximum extent from 1979 to 2023 is 0.1 percent per decade relative to the 1981 to 2010 average, which is not a significant trend.

However, since August 2016, the Antarctic sea ice extent trend took a sharp downturn across nearly all months (Figure 4c in previous post). Most research has suggested that changes in the near-surface ocean heat content is responsible for the sluggish growth in the past several months. A downturn in 2016 was attributed to a series of storms in the Weddell and Ross Sea regions that pushed the ice edge southward (Turner et al., 2017). Similar extremes in long-lived weather patterns like the record Amundsen Sea Low strength are implicated in the generally low ice extents of 2022 (Turner et al., 2022). However, this more recent excursion, beginning in May of 2023, and the general persistence of low sea ice extent near Antarctica since 2016, is now thought to be linked to warming in the uppermost ocean layer caused by lateral and upward mixing of warmer water (Zhang et al., 2022; Haumann et al., in press)

There is some concern that this may be the beginning of a long-term trend of decline for Antarctic sea ice, since oceans are warming globally, and warm water mixing in the Southern Ocean polar layer could continue. The Southern Ocean and its sea ice is an important component of Earth’s energy balance, reflecting sunlight back into space, and supporting a rich ice-edge ecosystem. Moreover, if dramatically lower sea ice extent continues to the 2024 summer minimum and beyond, much more of the Antarctic coastline will be exposed to ocean waves and marine climate. This may lead to two opposing impacts: erosion of more perennial coastal ice and ice shelves, destabilizing the ice sheet; or increased accumulation near the coast, offsetting in part the threat of rising sea level.

Line graph above shows Antarctic sea ice extent as of September 10, 2023, along with daily ice extent data for four previous years and the record maximum year. — Figure 2. The graph above shows Antarctic sea ice extent as of September 10, 2023, along with daily ice extent data for four previous years and the record maximum year. 2023 is shown in blue, 2022 in green, 2021 in orange, 2020 in brown, 2019 in magenta, and 2014 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data. — Credit: National Snow and Ice Data Center

Ten lowest maximum Antarctic sea ice extents (satellite record, 1979 to present)

**Table 1.** Ten lowest maximum Antarctic sea ice extents (satellite record, 1979 to present)
RANK	YEAR	MAXIMUM ICE EXTENT		DATE
RANK	YEAR	IN MILLIONS OF SQUARE KILOMETERS	IN MILLIONS OF SQUARE MILES	DATE
1	2023	16.96	6.55	Sept. 10
2	1986	17.99	6.95	Sept. 21
3	2002	18.05	6.97	Oct. 12
4	2017	18.10	6.99	Oct. 10
5	1989 2022 2018 2008	18.22 18.25 18.25 18.26	7.03 7.05 7.05 7.05	Sept. 25 Sept. 16 Oct. 03 Sept. 06
9	1984 1979	18.32 18.34	7.07 7.08	Sept. 23 Sept. 16

Values within 40,000 square kilometers (15,000 square miles) are considered tied.

References

Purich, A. and E. W. Doddridge. 2023. Record low Antarctic sea ice coverage indicates a new sea ice state. Communications Earth and Environment 4, 314, doi:10.1038/s43247-023-00961-9.

Turner, J., T. Phillips, G. J. Marshall, J. S. Hosking, J. O. Pope, T. J. Bracegirdle, and P. Deb. 2017. Unprecedented springtime retreat of Antarctic sea ice in 2016. Geophysical Research Letters, 44(13), 6868-6875, doi:10.1002/2017GL073656.

Turner, J., C. Holmes, T. Caton Harrison, T. Phillips, B. Jena, T. Reeves‐Francois, R. Fogt, E. R. Thomas, C. C. and Bajish. 2022. Record low Antarctic sea ice cover in February 2022. Geophysical Research Letters, 49(12), e2022GL098904, doi:10.1029/2022GL098904.

Zhang, L., T. L. Delworth, X. Yang, F. Zeng, F. Lu, Y. Morioka, and M. Bushuk. 2022. The relative role of the subsurface Southern Ocean in driving negative Antarctic Sea ice extent anomalies in 2016–2021, 3, 302, Communications Earth and Environment doi:10.1038/s43247-022-00624-1.

For more information

NASA visualization of 2023 Arctic sea ice minimum extent