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Published : 16 Apr 2026, 01:11 AM
The critical Atlantic Ocean current system is significantly more likely to collapse than previously thought, according to new research.
Scientists describe the study as “very concerning”, with potentially catastrophic consequences for Europe, Africa and the Americas, The Guardian reports.
The Atlantic meridional overturning circulation (Amoc), a key component of the global climate system, is already at its weakest level in 1,600 years due to the climate crisis.
Warning signs of a possible tipping point were first identified in 2021, and scientists note the system has collapsed in the Earth’s past.
Climate models used to project future changes in the Amoc have long produced widely varying results, ranging from little or no further slowdown by 2100 to a sharp deceleration of about 65 percent, even under scenarios where carbon emissions fall to net zero.
The latest study combined real-world ocean observations with climate models to identify the most reliable projections, significantly narrowing the uncertainty.
It found the Amoc is likely to slow by between 42 percent and 58 percent by 2100 -- a level scientists say would almost certainly lead to collapse.
The Amoc plays a crucial role in regulating climate by transporting warm tropical water northwards to Europe and the Arctic, where it cools, sinks and returns southwards at depth.
A collapse would disrupt global weather patterns, shifting tropical rainfall belts relied upon by millions for agriculture, bringing extreme cold winters and summer droughts to western Europe, and raising sea levels around the Atlantic by between 50cm and 100cm, The Guardian said.
Dr Valentin Portmann of the Inria Centre de recherche Bordeaux Sud-Ouest in France and lead author of the study, said the findings suggest the Amoc is “closer to a tipping point” than previously thought.
Prof Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research in Germany described the results as “important and very concerning”, adding that models previously considered pessimistic now appear to be the most realistic as they align better with observational data.
He warned that the tipping point beyond which a shutdown becomes inevitable could be reached as early as the middle of this century.
Rahmstorf, who has studied the system for 35 years, said earlier estimates put the risk of collapse at around 5 percent, but new evidence suggests it could now exceed 50 percent.
“The most dramatic and drastic climate changes we see in the last 100,000 years of Earth history have been when the Amoc switched to a different state,” he said, adding that collapse must be avoided “at all costs”.
The weakening of the Amoc is linked to rapid warming in the Arctic, which reduces the cooling and sinking of the ocean.
Warmer water is less dense and sinks more slowly, while increased rainfall freshens the ocean surface, further reducing density and creating a feedback loop that accelerates the slowdown.
Although the system is highly complex and influenced by natural variability, scientists now expect a significant weakening in the coming decades, which alone could have serious global impacts.
The research, published in the journal Science Advances, used four different methods to compare observational data with models.
A statistical approach known as ridge regression -- rarely used previously in climate science -- was found to produce the most reliable results.
Scientists say the improved accuracy stems from identifying models that better represent salinity patterns in the South Atlantic, a key factor in the system’s behaviour.
Rahmstorf, however, cautioned that even the new projections may underestimate the scale of change, as most models do not account for meltwater from the Greenland ice sheet, which is further freshening ocean waters and could accelerate the weakening of the current.
