A system of ocean currents could collapse anytime from 2025 onwards as climate change worsens, scientists have found.
The Atlantic Meridional Overturning Circulation (AMOC) is a large system of ocean currents that circulates water in the Atlantic, flowing warm water north and cold water south. The AMOC is crucial in keeping the world's oceans balanced. The circulation brings warmth to colder areas, and circulates nutrients that are integral to ocean life.
Research has already suggested that the currents are slowing due to changes in the world's climate. However whether it will completely halt has remained uncertain.
New research published in Nature Communications, from University of Copenhagen scientists, found that there is a possibility the system could completely collapse at the middle of our century.
"It was a surprise that it was found to be this early—at odds with what IPCC CMIP6 climate models predict," Peter Ditlevsen, one of the authors of the study, told Newsweek. "This is also why we developed rather advanced statistical tools to confirm the finding and to supplement with rigorous confidence bands."
Recent studies of the currents by the Intergovernmental Panel on Climate Change (IPCC), the U.N. body that assesses climate change-related science, suggest that a collapse would be unlikely in this century.
But this new research by Ditlevsen and co-author Susanne Ditlevsen suggests differently.
In their research, they analyzed North Atlantic sea surface temperatures from 1870 to 2020.
By using advanced statistical tools, the researchers found signs that the AMOC may not be far from a transition that would see it shut down.
They predicted this could happen from 2025, and no later than 2095.
If these findings are correct, it is hugely concerning. The collapse of the AMOC would trigger multiple climate tipping points, many of which could be irreversible.
"This current exists in the Atlantic, warming Western Europe, while it is absent in the Pacific, thus Alaska is a much colder place than Scandinavia at similar latitudes," Peter Ditlevsen said.
At the moment, the current circulates warm waters from the Gulf Stream to Europe. If it collapsed, this would also stop, and plunge parts of the continent into an intense freeze.
The AMOC is also integral in maintaining sea levels, which are already rapidly increasing due to climate change. This is because the flow of warm water to the north helps offset the increase in temperatures, which exacerbate changing sea levels.
This means its collapse would also cause a rapid sea level rise, including on the East Coast of the U.S.
A dramatic climate change like this was last seen during the Dansgaard-Oeschger events, which scientists predict happened around 25 times during the last 120,000 years.
These events saw the collapse of the AMOC which changed temperatures in the Northern Hemisphere by around 10 to 15 degrees Celsius over a decade.
To contrast, we have experienced a 1.5 degree change globally in the last century. The Dansgaard-Oeschger events are hard to study as the AMOC has only been closely studied since 2004.
Since research on the AMOC began, it is clear to scientists that it is indeed weakening, but there are conflicting reports as to whether this could lead to its eventual collapse, and when this could occur.
In this most recent study, the authors note the atmospheric CO2 concentrations have certainly increased in a linear fashion within the time period studied, the press release reported.
It is also noted that this estimated collapse could be partial.
