A hidden ocean change near Antarctica could have global consequences

Those impacts, he said, could include increased storm frequency and ocean heat loss identified by a 2024 study. Earlier this year, a far-reaching scientific review concluded that changes in Antarctic sea ice cover “influence the global distribution of atmospheric heat and moisture, as well as atmospheric variability.” The “speed and persistence” of the sea ice decline suggests the ocean around Antarctica may be moving into a new state that is likely to affect not only Antarctic ecosystems, but the entire global climate system, the review found.

Animation of Antarctic sea ice maximum extent, Sept. 10, 2023, to its minimum, Feb. 20, 2024.

Animation of Antarctic sea ice maximum extent, Sept. 10, 2023, to its minimum, Feb. 20, 2024.

Michael Meredith, an oceanographer with the British Antarctic Survey who led the BAS Polar Ocean for years, said the new research shows that dramatic Antarctic sea-ice loss since 2016 is already affecting the properties and circulation of deep ocean waters.

“The Southern Ocean is the key juncture for all the world’s oceans,” he said. “It’s the major site where old waters are reprocessed into new, so this could have global consequences.”

The Southern Ocean also plays a “massive role” in drawing down human carbon dioxide emissions, which moderates the rate of climate change where people live, he said. Anything that disrupts key ocean cycles demands our attention, he added.

Meredith said it’s not yet clear whether the shift is permanent because it’s based on a relatively short observational record. But, he said, global climate models used to guide policy still struggle to accurately reflect recent sea ice losses, which shows that more research and monitoring is needed.

“Our climate models need to catch up,” he said. “But if the low sea-ice state persists, these changes will keep spreading through the world’s oceans, and the effects will ripple out across our climate and ecosystems.”

Related research in recent years found that deep circulation in the Southern Ocean has slowed, reducing the rate at which new waters flood and cool the deepest areas. The new study makes it clear that the upper part is rapidly changing in response to changes in sea ice, he said. “That matters,” he added, “because the upper circulation can affect our climate within years to decades, not centuries.”

Bob Berwyn 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 assistant editor at community newspapers in the Colorado Rockies.

This story originally appeared on Inside Climate News.