Antarctica weather patterns changing, leading to record loss of ice: NCPOR study
The Antarctic sea ice retreat from September 2021 was close to the minimum sea ice extent (SIE) records since 1979, with the lowest in February 2022
The Antarctic sea ice (South Pole) reached its lowest level ever recorded in the summer of 2022, a study by the National Centre for Polar and Oceanic Research (NCPOR), headquartered at Vasco da Gama in Goa revealed.
In a paper published in the research publication, Environmental Research Publications, three scientists Juhi Yadav, Avinash Kumar and Rahul Mohan studied the atmospheric precursors that triggered the record low ice extent around Antarctica that revealed two weather events -- the positive polarity of Southern Annular Mode (SAM) that helped bring warmer air from higher latitudes towards the pole and the intensification of the low-pressure centre in the Amundsen Sea.
“Our study suggested that there are two dominant factors that eventually lead to low Antarctic sea ice record in February 2022: the positive polarity of Southern Annular Mode (SAM) and intensification of the low-pressure centre in the Amundsen Sea (ASL),” the researchers told HT.
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The Southern Annular Mode is a western wind pattern -- fast flowing winds blowing in the upper atmosphere around Antarctica -- that usually circulates the Antarctic ice shelf. If the low-pressure conditions (beyond standard conditions) develop over Antarctica this results in the winds flowing from the higher latitudes towards the poles leading to a receding lice line and pushing the sea ice away from the coast resulting in sea ice loss.
The ASL is a low-pressure atmospheric centre located off the coast of West Antarctica and over the southern Pacific Ocean
“These two atmospheric weather patterns significantly determine the sea ice extent (SIE) in the Southern Hemisphere. When SAM is in its positive phase (taking winds towards the pole), and ASL intensifies, it leads to ice loss that is most prominent in the western coast of Antarctica. Further, northward ice motion takes place and pushes ice farther to the north into warmer waters, thus resulting in increased melting. Therefore, understanding the atmospheric weather pattern and behaviour of SAM and ASL is essential for determining the Antarctic SIE.
Records reveal that the sea ice extent (SIE) reached a record low of 2.16 × 1,000,000 km2 in February 2022, which was 43% lower than the mean extent of the previous February months since the satellite era. The Weddell Sea, Ross Sea, and Bellingshausen/Amundsen Seas (ABS) sectors experienced the maximum sea ice change on a regional scale.
The Antarctic sea ice retreat from September 2021 was close to the minimum SIE records since 1979, with the lowest in February 2022.
The changing weather patterns in the Antarctic provide a grim foreboding for the future of the ice cap of the south pole, the researchers said.
“Based on recent studies and our findings, we found that Antarctic SIE is showing a sustained loss from 2016, and this could be a start of sea ice loss reported in the Arctic over the satellite period. In Antarctica, sea ice forms and grows freely in cold waters without land barriers. Thus, sea ice becomes thinner and weak, which can be easily drifted by the strong winds, especially in the regions of the Amundsen Sea,” the researchers said.
“The ocean-atmospheric interaction has a significant effect on the sea ice. These interactions and any changes in them are complex to understand. Earlier studies suggested that if the Antarctic sea ice loss continues to decline at this rate over the next few years, then it will equate to the rate of sea ice loss over 30 years in the Arctic, thus resulting in various global warming events,” the researchers added.
National Centre for Polar and Ocean Research (NCPOR) is India’s premier R&D institution responsible for the country’s research activities in the polar and Southern Ocean realms and conducts regular expeditions to maintain India’s research base on the frozen continent.
