Many of the extreme weather events now being experienced in the U.S. are linked to a weakening AMOC and an increasingly unstable, “wavier” jet stream. Both are driven by shifting temperature, pressure, and moisture gradients, and they are physically connected through shared feedback processes. As these feedbacks interact, they can amplify one another, accelerating the broader system toward destabilization.
A recent study highlights that the rate—and particularly the acceleration—of these changes may have been underestimated.
Led by Dr. Valentin Portmann at the Inria Centre de recherche Bordeaux Sud-Ouest, the research utilized a statistical method called ridge regression to assess climate models against real-world salinity observations in the South Atlantic.
- Underestimated Decline: The study found that previous “average” climate models likely underestimated how quickly the AMOC is weakening.
- Realistic Pessimism: Models previously considered “pessimistic” actually align better with observational data, making their severe outcomes more likely to be realistic.
- Tipping Point Proximity: Experts now suggest there is a greater than 50% chance of an AMOC shutdown tipping point being reached, possibly as early as the middle of this century (circa 2050).
Dr Valentin Portmann, at the Inria Centre de recherche Bordeaux Sud-Ouest in France and who led the new research, said: “We found that the AMOC is going to decline more than expected compared to the average of all climate models. This means we have an AMOC that is closer to a tipping point.”
Prof Stefan Rahmstorf, at the Potsdam Institute for Climate Impact Research in Germany, said: “This is an important and very concerning result. It shows that the ‘pessimistic’ models, which show a strong weakening of the AMOC by 2100, are, unfortunately, the realistic ones, in that they agree better with observational data. I now am increasingly worried that we may well pass that AMOC shutdown tipping point, where it becomes inevitable, in the middle of this century, which is quite close.”