Antarctic sea ice has reached its lowest extent since satellite records began in 1978, according to a new study from the Institute of Atmospheric Pyschics. The experts report that while many of the causes have been identified, there are still mysteries that remain.
In recent decades, the Arctic has been experiencing a rapid decline in sea ice as a result of global warming. Antarctic sea ice, on the other hand, has been showing an overall increase during the same time period.
In 2017, the southern hemisphere reached a record minimum extent of sea ice. Now, five years later, the same downward trend has been found in Antarctica.
A new record minimum in Antarctic sea ice extent was set on February 25, 2022, marking the first time in more than four decades that it has hit under two million square kilometers. Throughout the region, sea ice extent was about 30 percent lower than the average extent documented during the three decades of 1981 to 2010.
To investigate the causes of this phenomenon, the experts analyzed sea ice records from 1979 to 2022 from the National Snow and Ice Data Center (NSIDC).
The study revealed that in the summertime, ice loss is predominantly driven by thermodynamics, or the transfer of heat across Earth’s oceans. The experts also identified an increase in overall infrared radiation and visible light.
“Sea ice is whiter than the dark unfrozen sea, thus there is less reflection of heat and more absorption,” said study co-author and climatologist Qinghua Yang. “which in turn melts more sea ice, producing more absorption of heat, in a vicious cycle.”
In the spring, both thermodynamics and other dynamics contribute to the status of sea ice extent, the researchers found. They noted that according to data from the US National Oceanographic and Atmospheric Administration (NOAA), the new record Antarctic sea-ice extent minimum occurred at the same time as a combination of La Niña and a positive Southern Annular Mode (SAM).
Despite the breakthrough findings, there are questions to be answered.
“If tropical variability is having such an impact, it’s that location that needs to be studied next,” said study co-author Jinfei Wang.
The study is published in the journal Advances in Atmospheric Sciences.
By Chrissy Sexton, Earth.com Staff Writer