The Antarctic’s sea ice is experiencing an unusual phenomenon as its areal expanse reaches record lows. Surpassing the previous record set in 2022, the ice extent has been consistently hitting record lows throughout the year, marking a significant decline that is distinct from the well-known Arctic sea ice decline.
Mark Serreze, a climate scientist and the director of the U.S. National Snow and Ice Data Center (NSIDC), explains that unlike the Arctic sea ice, which has been known to dramatically decline due to global warming, Antarctica’s sea ice had remained relatively stable until recent years. However, it has now plummeted.
The NSIDC monitors the spread of sea ice using satellite data collected daily. Throughout most of 2023, the sea ice around Antarctica has consistently set new record lows, remaining well below the average extent observed from 1981 to 2010. On February 21, during the Southern Hemisphere’s summer, the sea ice reached an all-time low since record-keeping began in 1978, measuring 1.79 million square kilometers. This is 130,000 square kilometers smaller than the previous minimum recorded on February 25, 2022, roughly equivalent to the size of the state of New York.
Even as the Southern Hemisphere transitioned into winter, the Antarctic sea ice continued to remain at record low levels. By June 27, it covered approximately 11.7 million square kilometers of ocean, which is about 2.6 million square kilometers below the 1981-2010 average and 1.2 million square kilometers below the previous lowest extent recorded on June 27, 2022.
Unlike the Arctic ice, the reasons for changes in Antarctic sea ice extent have been harder to decipher. Determining whether these changes are a result of natural variability or a significant shift in the system remains challenging. The recent years have raised concerns among scientists, prompting discussions about whether something substantial has changed.
The distinct geographic settings of the Arctic and the Antarctic contribute to their differing ice dynamics. The Arctic Ocean is surrounded by land, resulting in a relatively confined ice cover, whereas Antarctica is a landmass surrounded by ocean, allowing for greater mobility and larger seasonal fluctuations in sea ice extent. Climate simulations have consistently predicted that the Arctic would experience more significant sea ice losses initially, while Antarctica would respond more slowly to global warming.
Several factors could be responsible for this year’s exceptionally low Antarctic sea ice. Regional climate patterns, such as the Southern Annular Mode, which affects wind directions around the continent, can impact the concentration of sea ice. Additionally, phenomena like the El Niño Southern Oscillation can influence ocean and air circulation in the southern high latitudes.
Currently, the focus of scientists is primarily on the conditions beneath the Antarctic ice. Recent evidence suggests that there might be a shift in ocean circulation, leading to an increased influx of heat into the region, which directly impacts the ice cover. Mark Serreze emphasizes the importance of this matter, stating that numerous researchers are actively investigating the situation. Efforts are being made to gather comprehensive data and gain a deeper understanding of the oceanic changes occurring in the Antarctic.