No one really knows how close it may be.

In 2021, the IPCC said it had “medium confidence” that Amoc would not collapse abruptly this century, although it expected it to weaken.

But some more recent studies have pointed to a growing possibility of Amoc passing a tipping point in the coming decades, beyond which full collapse would be inevitable.

Each study comes with various caveats and uncertainties, and different climate models can give different results for a system as complex as Amoc.

“We don’t believe the idea of an Amoc collapse this century has substantially changed because of these new results,” cautions Dr Laura Jackson, oceanographer at the Met Office.

But many scientists are growing increasingly concerned. Prof Thornalley argues that, whatever the imperfections of individual studies, taken together they “lead to a conclusion that we maybe need to be worried”.

Following the new evidence, more than 40 leading ocean and climate scientists signed an open letter, external last October calling for wider recognition of the “greatly underestimated” risks.

That is not to say the signatories believe Amoc will pass a tipping point this century. But they warn it is now enough of a possibility to warrant proper consideration.

“I’d say you’re looking at a risk of reaching a tipping point in the coming decades that could be at the 10 or 20% level even if we hold the line at 2C warming [above temperatures of the late 19th Century, before humans started significantly warming the climate],” warns Tim Lenton, professor of Earth system science at the University of Exeter.

Given the magnitude of the consequences from Amoc collapse, these probabilities “are not trivial,” he adds.