The AMOC, crucial for Earth’s climate, has remained stable over the past 60 years, per a WHOI study. Advanced methods show no significant decline, challenging earlier research. While its future stability under climate change remains uncertain, there is still time to act.
Earth, with 71% of its surface covered by water, is profoundly influenced by the ocean and its movements. A key player in this dynamic system is the Atlantic Meridional Overturning Circulation (AMOC), a network of interconnected currents in the Atlantic Ocean. Driven by a combination of winds and ocean density differences, the AMOC circulates water across the globe, redistributing heat, moisture, and nutrients while playing a critical role in regulating Earth’s climate and weather systems.
As climate change accelerates and the atmosphere warms, scientists are increasingly concerned that fresh water from melting polar ice sheets could severely disrupt—or even collapse—the AMOC. While a decline would have serious global repercussions, a collapse would be catastrophic. However, the long-term future of the AMOC remains uncertain. To address this uncertainty, researchers from the Woods Hole Oceanographic Institution (WHOI) turned to the past, analyzing historical data to better understand the potential trajectory of this vital ocean circulation system.
Findings on the AMOC’s Recent Stability
In a new paper published in Nature Communications, scientists found that the AMOC has not declined in the last 60 years. Authors Nicholas P. Foukal, adjunct scientist in Physical Oceanography at WHOI and assistant professor at the University of Georgia; Jens Terhaar, affiliated scientist at WHOI and senior scientist at the University of Bern; and Linus Vogt, visiting student at WHOI when he started to work on this study and now a scientist at LOCEAN, Sorbonne Université, say their results mean that the AMOC is currently more stable than expected.
“Our paper says that the Atlantic overturning has not declined yet,” Foukal said, who conducted the research while at WHOI. “That doesn’t say anything about its future, but it doesn’t appear the anticipated changes have occurred yet.”
Their findings contrast with previous work, notably a paper from 2018 cited in their study, which reported that the AMOC has declined over the last 70 years. This past work relied on sea surface temperature measurements to understand how the AMOC has changed, but “we’ve learned that sea surface temperature doesn’t work as well as initially thought,” said Terhaar, who began leading this study at WHOI as a postdoctoral scientist and completed the work in Bern.
Improved Data and Methodology
To address the uncertainty, Terhaar and the team relied on new data from the Coupled Model Intercomparison Project (CMIP), climate-earth models produced by the World Climate Research Program. They used 24 different CMIP models and found that the most recently available surface temperature data did not accurately reconstruct the AMOC. To go a step further, the researchers looked at a different measure: air-sea heat fluxes, which is the exchange of heat from the ocean to the atmosphere. When the AMOC is stronger, more heat is released from the ocean to the atmosphere over the North Atlantic.
The authors derived this AMOC proxy with the CMIP models, then applied it to observational data. The best data for surface heat fluxes over the North Atlantic come from reanalysis products that incorporate direct observations into a model, similar to the way weather forecasts work. The study authors focused on two reanalysis data sets that extend back to the late 1950s to reconstruct the AMOC.
“Based on the results, the AMOC is more stable than we thought,” Vogt said. “This might mean that the AMOC isn’t as close to a tipping point as previously suggested.”
Implications and Limitations
The paper states that air-sea heat flux anomalies in the North Atlantic are tightly linked to the AMOC and that “the decadal averaged AMOC has not weakened from 1963 to 2017.” Since there are many processes that lead to large year-to-year variability in the AMOC, the air-sea heat flux and the AMOC are correlated strongest at those timescales, as opposed to annual averages.
“It’s almost unanimous at this point that the Atlantic overturning will slow in the future, but whether or not it will collapse is still up for debate,” Foukal said. “This work indicates that there is still time to act before we reach this potential tipping point.”
As with all proxy-based reconstructions, there are limitations and caveats. The authors point out that direct measurements of air-sea heat flux going back in time are sparse, and thus the reanalysis products contain significant uncertainty. However, despite these limitations, “a decline in AMOC over the last 60 years,” Terhaar concludes “seems very unlikely.”
Reference: “Atlantic overturning inferred from air-sea heat fluxes indicates no decline since the 1960s” by Jens Terhaar, Linus Vogt and Nicholas P. Foukal, 15 January 2025, Nature Communications.
DOI: 10.1038/s41467-024-55297-5
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.
13 Comments
I see scientists claiming man made climate change without considering the suns activities and water currants without considering the wind. My assumptions in life is all things have to be considered.
Problem is folks have political agenda imbedded into their thinking and analytical strategy
and confirmation bias
In a few thousand years, the earth’s climate will be warmer, when the earth’s air warms up, the earth will be cold again because of the clouds that block the sun’s light. They will collide and the life of the earth will be renewed
No. It’s gonna be rather cold and dry if we do not do something about it. CO2 is merely a delay if a few centuries at best. And in fact, things attributes to “global warming” are things I currently suspect are signs of early stage glaciation
we’re at the peak of the Milankovitch cycles, so your observation is likely correct. Historically the peak is volatile until is tips and falls rapidly into a cooling cycle.
Debate the timetable and/or acceleration of climate change all you want, but to deny it’s happening is the height of human hubris. Our planet is much like a terrarium, and we cannot kept adding waste and carbon emissions without consequence and causing imbalances in the ecosystem. We can afford to mitigate the effects, if scientists are wrong about human activity causing the warming trend we end up with more green technology and renewables and jobs that go with them. What we cannot afford is doing nothing. That will portend disaster with our coastlines under water and worse.
The words climate change do not mean the same as anthropogenic climate warming. These are word games used to manipulate political agenda
The earth has been greening for decades, people should be happy that we’re currently in an interglacial period. Life thrives in a warm and wet environment. Life struggles to cope with cold and frozen environments. I don’t understand the irrational fear of global warming, its global COOLING that people should be concerned about.
Yes. Frost and wind are the biggest enemies of food production, not warmth and more rain from increased evaporation.
Yep, but when it starts to get too hot because of us, it will get very cold very quickly, to put it simply, ergo the living conditions will become worse, so, maybe it’s better not to add to the stove, right? 😉
thank you
Totally awesome perfection that the unification theory is coming together with religion and politics!