Antarctica is in the middle of winter, but the continent is surrounded by far less sea ice than scientists expect for this time of year. In July 2023, the average size of sea ice was 13.5 million square kilometers (5.2 million square miles), the lowest level observed at this time of year since continuous satellite records began in late 1978.

sea ​​ice observation

The map above shows Antarctic sea ice coverage as of August 7, 2023, based on satellite data provided by the National Snow and Ice Data Center (NSIDC), one of NASA’s distributed active archive centers.

Antarctic sea ice follows a seasonal trend, with about 15 million square kilometers of ice growing and melting each year. Ice growth has been very slow this winter. In July, sea ice covered an area of ​​about 2 million square kilometers (an area the size of Mexico), below the 1981-2010 average. The yellow line shows the average sea ice area for the month of July from 1981 to 2010.

Regions with low ice levels

The map shows that the ice field is low in almost all parts of the continent. Individual low-ice areas included the northeastern Weddell Sea, northern Ross Sea, and eastern Bellingshausen Sea. Interestingly, the Amundsen Sea was the only area with an above-average length.

“We’re seeing unexplored regions in the satellite record this year,” said Walt Meier, a sea ice researcher at NSIDC. According to the NSIDC, the average sea ice size in July 2023 was 1.5 million square kilometers (579,000 square miles) below the previous record low July size seen in 2022. The chart below shows the daily amount of sea ice (red) up to August 7, 2023, compared to the record low in 2022 (orange) and the average amount of ice from 1981 to 2010 (blue).

downtrend

This record low area in 2023 is a continuation of the downward trend in Antarctic sea ice that began after the record high in 2014. By 2014, icing around the continent had increased slightly over the long term (about 1 percent per decade). ). But it has since fallen sharply, hitting record levels in 2017, 2022 and now 2023. “Most months since 2016 have been well below average,” Meyer said. The reason for such a change is not yet clear to scientists.

Scientific perspectives and research

“The increase in the Antarctic sea ice area before 2014 and the rapid decline since then is of great interest to scientists, but there is no consensus on the driving factors,” said Claire Parkinson, a climate scientist at NASA’s Goddard Space Flight Center. Parkinson is an expert in using satellite observations to map sea ice size and was part of the team that published the first satellite-based atlas of Antarctic sea ice in 1983.

Recent research by Parkinson showed that the rate of sea ice decline around Antarctica between 2014 and 2017 far exceeded the decline seen in Arctic sea ice in recent years, a decline far greater than that observed in the entire 40-year satellite record.

Assumptions and future studies

Some scientists are wondering whether the sudden change in Antarctic sea ice indicates a shift towards less ice overall. While Mayer says it’s too soon to say whether this is the case, recent research suggests changing ocean conditions may be a factor. Ocean heat may play a stronger role in limiting autumn and winter ice growth and increasing spring and summer melting. Source