Antarctic Sea Ice Is at a ‘Very Concerning’ Record Low
22 million sq. km 20 Each line shows one yearly cycle of sea ice. The dotted line is the average from 1979 to 2010. 18 16 14 12 10 July 2023 Antarctic sea ice extent is far below where it typically would be in winter. 8 6 4 2 0 Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. 22 million sq. km 20 18 Each line shows one yearly cycle of sea ice. The dotted line is the average from 1979 to 2010. 16 July 2023 Antarctic sea ice extent is far below where it typically would be in winter. 14 12 10 8 6 4 2 0 Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. National Snow and Ice Data Center Leanne Abraham and Its winter in the Southern Hemisphere, when ice typically forms around Antarctica. But this year, that growth has been stunted, hitting a record low by a wide margin. The sharp drop in sea ice is alarming scientists and raising concerns about its vital role in regulating ocean and air temperatures, circulating ocean water and maintaining an ecosystem crucial for everything from microscopic plankton to the continents iconic penguins. This year is really different, said Ted Scambos, a senior research scientist at the University of Colorado Boulder and an Antarctica expert at the National Snow and Ice Data Center. Its a very sudden change. A continued decline in Antarctic sea ice would have global consequences by exposing more of the continents ice sheet to the open ocean, allowing it to melt and break off more easily, contributing to rising sea levels that affect coastal populations around the world. Less ice also means less protection from solar rays, which can raise the water temperature, making it harder for ice to form. At the end of June, ice covered 4.5 million square miles, or 11.7 million square kilometers, of ocean around the continent, according to NSIDC . Thats nearly a million square miles less than the expected average from approximately 40 years of satellite observations. The clear departure from previous years is startling, since sea ice around Antarctica has been slower to respond to climate change than . July 2023 Mean sea ice concentration 0% 100% Median July ice extent 1981-2010 Weddell Sea Antarctica 60 S Ross Sea Sea ice does not extend as far into the Ross Sea as it typically does. July 2023 Mean sea ice concentration 0% 100% Median July ice extent 1981-2010 Weddell Sea Ice Shelf Antarctica Ice Shelf 60 S Ross Sea Sea ice does not extend as far into the Ross Sea as it typically does. National Snow and Ice Data Center Leanne Abraham Antarctic sea ice , but this years ice cover is almost half a million square miles smaller. The Antarctic sea ice extent low in 2023 is unprecedented in the satellite record, Liping Zhang, a project scientist at the National Oceanic and Atmospheric Administrations Geophysical Fluid Dynamics Laboratory, wrote in an email. The record low might signal a shift in the sea ice system to a new, unstable state where extremes become more common, but Dr. Zhang cautioned that scientists are still investigating this question. Sea ice around Antarctica typically freezes from February to August and then melts until the next Southern Hemisphere winter. Several ocean and atmosphere patterns influence how much ice grows or shrinks, and the . On top of these natural, short-term patterns is the long-term influence of humans burning fossil fuels that add greenhouse gases to the atmosphere. Some researchers suspect that we are finally seeing the effects of this slow burn on Antarcticas previously resilient sea ice. This years change, within the context of several years in a row with less sea ice, is very, very concerning, said Marilyn Raphael, a geography professor and director of the Institute of the Environment and Sustainability at University of California, Los Angeles. That is not within natural variability, she said. Dr. Raphael has been working to extend the historical record of Antarctic sea ice past the 1970s, when satellite observations began. She and her colleagues recently published , using weather observations to reconstruct the extent of sea ice during earlier years. While its still limited data, the longer record captures more cycles of natural variability. Dr. Raphael and other experts think that the ocean, which warms up more slowly than the atmosphere and has absorbed much of the heat from the burning of fossil fuels, may have reached a point where that heat is affecting Antarctic sea ice. Sea surface temperatures have broken , and there are currently three patches of unusually warm water around Antarctica. While other factors are also at play, these hot spots line up with the areas on the coast where sea ice has been unusually slow to form, said Dr. Scambos. The sea ices decline is causing real consequences both locally and globally. Both of Antarcticas native penguin species rely on sea ice. In some parts of the continent, , a tiny crustacean that thrives in icy water. Less sea ice means less krill and less food for Adelies. Larger emperor penguins, recently , depend even more directly on sea ice: they lay their eggs and raise their young on these floating habitats. When sea ice melts earlier in the season, before emperor penguin chicks develop waterproof adult feathers, the chicks can drown. Sea ice also serves as a protective, frozen moat around Antarctica shielding the continental ice sheet and its glaciers, which have already been destabilized by climate change, from the warmer ocean and the eroding force of wind and waves. If this shield disappears, more land ice could flow or fall into the ocean, though some of this loss could be counterbalanced by more snow falling onto the continent. is one of the biggest factors in determining sea level rise. Even when Antarctic sea ice reaches its maximum extent around September, it could remain at a record low for that time of year, said Xiaojun Yuan, a research scientist at Columbia Universitys Lamont-Doherty Earth Observatory, who maintains . Dr. Yuans forecast shows less sea ice than usual around most of Antarctica at least through early 2024.