Antarctic Ice High is Low

National Snow and Ice Data Center:

On September 17, 2025, Antarctic sea ice extent likely peaked with a maximum of 17.81 million square kilometers (6.88 million square miles), the third lowest maximum in the satellite record that began in 1979 . This year’s extent is 740,000 square kilometers (286,000 square miles) above 2023, the record low maximum. It is 900,000 square kilometers (348,000 square miles) below the 1981 to 2010 average Antarctic maximum extent. Sea ice extent is markedly below average in the Indian Ocean and the Bellingshausen Sea (Figure 1b). Extent is slightly above average stretching out of the Ross Sea.

The Antarctic maximum extent is six 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. 

National Snow and Ice Data Center:

After decades of watching Arctic sea ice extent drop as climate warms, scientists have yet to see Antarctic sea ice set a definitive trend. “Antarctic sea ice has always been a puzzle,” said Sharon Stammerjohn, senior researcher at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado Boulder. Its extents have waxed and waned from lows to highs within a year.  

But what happened in the winter of 2023 still shocked scientists.  

“It was completely off the rails,” said Ted Scambos, senior researcher with the Cooperative Institute for Research in Environmental Sciences (CIRES). Throughout the 2023 austral winter, sea ice was far below any previous winter extent in the 45-year satellite record. On September 10, 2023, Antarctic sea ice bottomed out at 1.75 million square kilometers (676,000 square miles) below the 1981 to 2010 average. Sea ice extent also hit a record low in the summer of 2023 for a second year in a row. In fact, 2017, 2018, and 2022 all hit record lows.  

Now scientists are eager to know if climate change has finally caught up with Antarctic sea ice. Several recent studies explore that idea using statistical analysis of sea ice extent data from the NASA NSIDC Distributed Active Archive Center (DAAC). Their analyses may also have found the culprit behind the dramatic changes taking place in the Southern Hemisphere: ocean temperatures. The consequences of a warming ocean may stretch far beyond the Antarctic Ice Sheet, which holds enough land ice to sink low-lying coastlines around the world.