„Uncharted territory” – exceptionally low Antarctic sea ice observed by NASA

The extent of winter sea ice around Antarctica is in uncharted territory in the satellite record.

Antarctica is experiencing the depths of winter, although the continent is surrounded by significantly less sea ice than scientists expected at this time of year. Throughout July 2023, sea ice averaged 13.5 million square kilometers (5.2 million square miles), marking the lowest extent for the year since continuous satellite recording began in late 1978.

Sea ice observations

The map above shows Antarctic sea ice extent on August 7, 2023. National Snow and Ice Data Center (NSIDC), one NASAs Distributed Active Archive Centers.

Antarctic sea ice follows a seasonal trend, and about 15 million square kilometers of ice grows and melts each year. Snow growth is very slow this winter. In July, sea ice was about 2 million square kilometers (the size of Mexico) less than the 1981-2010 average. The yellow line shows the average sea ice extent from July 1981 to 2010.

Areas with less snow

The map indicates that snow levels were low everywhere around the continent. Specific areas of low ice include the northeastern Weddell Sea, the northern Ross Sea, and the eastern Bellingshausen Sea. Interestingly, only the Amundsen Sea was above average.

„What we’re seeing this year is an area that hasn’t been covered in the satellite record,” said Walt Meyer, a sea ice scientist at NSIDC. Average sea ice extent in July 2023, according to NSIDC 1.5 million square kilometers That’s less than the previous record-low July amount seen in 2022 (579,000 square miles). The chart below shows daily sea ice extent through August 7, 2023 (red), compared to the lowest recorded in 2022 (orange) and the average from 1981 to 2010 (blue).

downward trend

This record low in 2023 is a continuation of the downward trend in Antarctic sea ice. It followed a record high in 2014. Prior to 2014, the ice around the continent was frozen for long periods (ca 1 percent per decade) but since then, it has taken a sharp decline with the lowest in 2017, 2022 and now 2023. „Most months since 2016 have been below average,” the mayor said. The reason for this change is still unclear to scientists.

Scientific views and research

„Both the increase in Antarctic sea ice before 2014 and its rapid decrease are of great interest to scientists, with no consensus on the drivers,” said Claire Parkinson, a climate scientist at NASA’s Goddard Space Flight Center. Parkinson specializes in using satellite observations to map sea ice extent, and in 1983 he was one of the team that published the first atlas of Antarctic sea ice from satellite data.

Parkinson’s disease Recent research The rate of sea ice decline around Antarctica between 2014 and 2017 exceeded the decline seen in Arctic sea ice in recent years, and was the largest decline of any seen in the entire 40-year satellite record.

Speculations and future studies

Some scientists speculate that the sudden reversal of Antarctic sea ice indicates a shift toward lower ice extent in general. Although Meier stressed that it is too early to determine whether this is the case, recent studies suggest that changing ocean conditions may be a factor. Ocean heat can come into play A strong character Limits fall and winter snow development and enhances spring and summer melt.

NASA Earth Observatory images by Lauren Dauphin using data from the National Snow and Ice Data Center.