Study suggests likelihood of Atlantic current collapse higher than expected. A study published on Friday issued a warning that the likelihood of a systemic collapse of the Atlantic Ocean currents, responsible for transporting warm water from the tropics to Europe, may be higher than previously thought. This event could lead to a sharp drop in temperatures across much of the continent.
The Atlantic Meridional Overturning Circulation (AMOC), which includes the Gulf Stream, is potentially on a trajectory towards a sudden shutdown, described by René Van Western, the lead researcher of the Dutch study published in Science Advances, as "cliff-like."
For thousands of years, the Gulf Stream has transported warm waters from the Gulf of Mexico northward along the eastern North American coast and across the Atlantic to Europe. However, due to human-induced global warming, the melting of the Greenland ice sheet is releasing vast amounts of freshwater into the North Atlantic. This influx of freshwater is cooling the AMOC, which carries most of the Gulf Stream's heat, pushing it closer to a "tipping point" that could halt the current altogether.
If the AMOC were to shut down, temperatures would increase in the Southern Hemisphere but drop significantly in Europe. According to the study's model, London would experience an average cooling of 18°F, while Bergen, Norway could see a drop of 27°F. Additionally, an AMOC failure would lead to rising sea levels along the east coast of North America.
"We are moving closer [to the collapse], but we're not sure how much closer," van Westen told reporters. "We are heading towards a tipping point."
A ship in the Atlantic Ocean
According to the study:
While AMOC collapses have been triggered in complex global climate models through intense freshwater forcing, the mechanisms behind an AMOC tipping event have not yet been thoroughly explored. In this study, we present the findings of the first tipping event observed in the Community Earth System Model, highlighting the significant climate impacts of such a collapse. These results lead us to propose a physics-based and observable early warning sign for AMOC tipping: the lowest level of freshwater transport caused by AMOC at the southern boundary of the Atlantic. Reanalysis data suggests that the present-day AMOC is progressing towards a tipping point. This early warning signal offers a valuable alternative to traditional statistical indicators, which, when applied to our simulated tipping event, prove to be sensitive to the analyzed time interval preceding the tipping point.- The study
“The research makes a convincing case that the AMOC is approaching a tipping point based on a robust, physically based early warning indicator,” said Tim Lenton, director of the University of Exeter’s Global Systems Institute. “What it cannot and does not say is how close the tipping point, because… there is insufficient data to make a statistically reliable estimate of that.
"We have to plan for the worst," added Lenton, who was not involved in the Dutch study. "We should invest in collecting relevant data and improving the estimation of how close a tipping point is, improving assessment of what its impacts would be, and getting pre-prepared for how we could best manage and adapt to those impacts if they start to unfold."
Stefan Rahmstorf, who heads the Earth Systems Analysis department at the Potsdam Institute for Climate Research in Germany and was not involved in the recent study, described the research as "a significant step forward in AMOC stability science."
"The new study adds significantly to the rising concern about an AMOC collapse in the not-too-distant future," Rahmstorf told reporters. "We will ignore this at our peril."