Slowing ocean current caused by melting Antarctic ice could have drastic climate impact, study says
The Southern Ocean overturning circulation has ebbed 30% since the 90s, CSIRO scientist claims, leading to higher sea levels and changing weather
Donna Lu, Guardian, 26 May 23
A major global deep ocean current has slowed down by approximately 30% since the 1990s as a result of melting Antarctic ice, which could have critical consequences for Earth’s climate patterns and sea levels, new research suggests.
Known as the Southern Ocean overturning circulation, the global circulation system plays a key role in influencing the Earth’s climate, including rainfall and warming patterns. It also determines how much heat and carbon dioxide the oceans store.
Scientists warn that its slowdown could have drastic impacts, including increasing sea levels, altering weather patterns and depriving marine ecosystems of vital nutrients.
“Changes in the overturning circulation are a big deal,” said the study’s co-author, Dr Steve Rintoul, an oceanographer and expert on the Southern Ocean at the Australian government’s Commonwealth Scientific and Industrial Research Organisation (CSIRO)
It’s something that is a concern because it touches on so many aspects of the Earth, including climate, sea level, and marine life.”
The finding comes months after modelling, which Rintoul was involved in, that predicted a 40% slowdown in the circulation by 2050.
“The model projections of rapid change in the deep ocean circulation in response to melting of Antarctic ice might, if anything, have been conservative,” Rintoul said. “We’re seeing changes have already happened in the ocean that were not projected to happen until a few decades from now.”
………………………………………….. The study looked specifically at changes in overturning circulation in the Australian Antarctic basin, but the researchers believe a “circumpolar slowdown” is occurring.
“We expect in the longer term that while there will be ups and downs related to sea ice formation, the overall trend is that Antarctica is losing more ice, is melting more, and that will gradually slow down this overturning circulation.
“Unless we act soon we will commit ourselves to changes that we’d really rather avoid,” he said. “We need to act to reduce emissions and we need to do everything we can as fast as we can.”
The study, whose first author is Kathryn Gunn of the CSIRO and the University of Southampton, was published in the journal Nature Climate Change. https://www.theguardian.com/science/2023/may/25/slowing-ocean-current-caused-by-melting-antarctic-ice-could-have-drastic-climate-impact-study-says
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