A recent study paints a much more dire picture of the Atlantic Meridional Overturning Circulation (Amoc). Its collapse is no longer a low-probability event – it’s a likely scenario. The AMOC is responsible for transporting warm tropical water to Europe and cooling the Arctic. There, it cools and sinks, producing a deep return current. As climate change continues to exert pressure on this vital system, experts warn that the implications of its potential collapse could be catastrophic for millions globally.
The research confirms that the Amoc is currently at its weakest in at least 1,600 years. This shocking state of affairs is primarily due to the deepening climate emergency. It will jump-start severe changes to the position of the tropical rainfall belt. This change will threaten agricultural productivity for millions of communities who depend on predictable weather to produce their crops. Not only that, it would doom Western Europe to frigid cold winters and dry summers, dramatically changing the European climate.
While the potential collapse of the AMOC is a cause for deep concern, it would contribute the equivalent of about 50 centimeters of sea level rise, which would further exacerbate coastal flooding and erosion. Paleoclimate records suggest that the Atlantic Meridional Overturning Circulation (AMOC) has collapsed repeatedly in the Earth’s history. Scientists are cautioning that we may reach the tipping point for its shutdown in just a few decades.
The rest of the study uncovers an incredible story that’s very important. Even though the Amoc’s collapse is not immediate, it could occur 50 to 100 years after we pass the tipping point. In 25% of climate models studied, a collapse happened even in low future carbon emission pathways. If emissions are allowed to keep climbing freely, 70% of the models forecasted an Amoc collapse. A medium level of emissions led to a 37% chance of shutting down.
This is the kind of number that would make your eyes pop out,” concluded Prof Stefan Rahmstorf, one of the study’s authors. Until recently I thought that the likelihood of AMOC collapsing as a direct result of global warming was no more than 10%.
He emphasized the shifting probabilities. “Now even in a low-emission scenario, sticking to the Paris agreement, it looks like it may be more like 25%.”
And the reason why is that crossing the tipping point actually increases the chance of triggering an Amoc shutdown. This is because of dangerous self-amplifying feedback loops operating in the climate system. Prof. Sybren Drijfhout observed that “observations in the deep far North Atlantic already show a downward trend over the past five to 10 years, consistent with the models’ projections.” This recent decline has sparked a new wave of worry over the stability of the Amoc.
The exact timing of an Amoc collapse is still a question mark. Dr. Aixue Hu cautioned that while there is a consensus on the increasing risk, “it is still very uncertain when Amoc collapse will happen or when the Amoc tipping point is going to be crossed because of the lack of direct observations [of the ocean] and the varying results from the models.”
Dr. Jonathan Baker added that this new research emphasizes that “the risk rises after 2100,” although he urged caution regarding interpretations of these findings. “These percentages should be treated with caution – the sample size is small, so more simulations [beyond 2100] are needed to better quantify the risk.”
Even with these uncertainties, experts are in accord on one point: even a low probability of potential collapse has dangerous consequences. Prof. Rahmstorf noted, “These numbers are not very certain, but we are talking about a matter of risk assessment where even a 10% chance of an Amoc collapse would be far too high.”