Antarctica’s dramatic sea-ice loss since 2016 is already affecting the Southern Ocean’s deep circulation, according to British Antarctic Survey oceanographer Michael Meredith. Scientists warn that continued low sea-ice levels could alter ocean cycles with consequences for global climate and ecosystems, although it remains uncertain whether the shift is permanent.
Potential impacts include more frequent storms and the loss of heat from the ocean, according to a 2024 study. A scientific review published earlier this year concluded that changes in Antarctic sea-ice extent “influence not only atmospheric variability but also the global distribution of atmospheric heat and moisture.”
The “speed and persistence” of the sea-ice loss suggest that the ocean around Antarctica may be transitioning to a new state, the review said. That shift could affect both the Antarctic ecosystem and the global climate system.
Changes in Southern Ocean circulation
Michael Meredith, a British Antarctic Survey oceanographer and longtime head of BAS Polar Oceans, said the study showed that Antarctica’s sharp sea-ice decline since 2016 was already affecting the nature and circulation of the deep ocean.
“The Southern Ocean is a critical watershed for all of the world’s oceans,” he said. “This could have global implications, as this is a major site where old water is reprocessed into new water.”
The Southern Ocean also plays a “huge role” in absorbing human carbon dioxide emissions and slowing the pace of climate change in populated regions, Meredith said. Any disruption to these important ocean cycles requires attention, he added.
Meredith said it is not yet clear whether the change is permanent because the conclusion is based on a relatively short observational record. Global climate models used to guide policy also continue to struggle to accurately represent the recent loss of sea ice, highlighting the need for further research and monitoring.
“Our climate models need to catch up,” he said. “However, if sea-ice levels remain low, these changes will continue to spread across the world’s oceans, with ripple effects across climate and ecosystems.”
Effects that could emerge within decades
Related research in recent years has found that deep circulation in the Southern Ocean is slowing, reducing the rate at which new water flows in and cools the deepest parts of the ocean.
New research indicates that the upper ocean is changing rapidly in response to changes in sea ice, Meredith said. “That’s important because upper circulation can affect our climate within years to decades, rather than centuries,” he added.
Bob Barwin is an Austria-based reporter who has covered climate science and international climate policy for more than a decade. Previously, he reported on the environment, endangered species, and public lands for several Colorado newspapers, and also worked as editor and associate editor for a community newspaper in the Colorado Rockies.
This story was originally published by Inside Climate News.
Source: arstechnica.com
