Claim: “The AMOC current won’t collapse this century – the warnings are exaggerated.”
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In the film, Professor Tim Lenton explains that the Atlantic circulation (the AMOC), which keeps Britain mild, “can pass and does pass a tipping point” in a number of leading climate models. In his full briefing, he puts the odds at “definitely worse than Russian roulette” if warming goes anywhere near 2°C, and at least “as likely as not” near 3°C.
The latest research backs him up: leading ocean scientists now estimate a risk of around 1 in 4, even with low emissions. The consequences of AMOC shutdown are so severe, that even a smaller risk should be taken extremely seriously - not brushed aside.
Who would board a plan that had even a 1% chance of crashing, let alone one in six or one in four?
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What Professor Lenton says. In the film, he explains that the AMOC “can pass and does pass a tipping point in a bunch of the state-of-the-art climate models”, and describes what Britain would face if it did, using one such model as an example: winter extremes of around -20°C in London, a collapse in our ability to grow crops, and a water security crisis in the south-east.
In his full briefing, he adds that “if we go anywhere near 2°C, then the odds of crossing that tipping point are definitely worse than Russian roulette”, and that it “will be at least ‘as likely as not’ if we go anywhere near 3°C”. These are risks, not forecasts. That’s exactly why they matter.
The latest research supports those odds. A 2025 study led by Sybren Drijfhout and Stefan Rahmstorf ran climate models beyond 2100. It found the AMOC shut down in 70% of runs under high emissions, 37% under intermediate emissions and 25% even under low emissions. The authors said collapse can no longer be treated as a “low-likelihood” event. Professor Rahmstorf, who once put the risk below 10%, now estimates around 25% even on a low-emission path. One in four is worse than Russian roulette.
Tipping now, collapse later. Critics often quote the IPCC’s 2021 assessment of “medium confidence” that there will be no abrupt collapse before 2100. But passing the tipping point and the collapse itself are different things. The tipping point could be crossed within decades, locking in a collapse that unfolds over the following 50–100 years. The IPCC's assessment is also of course now somewhat out-of-date.
What it would mean for Britain. Research shows that if the AMOC collapsed, London could face once-a-decade winter cold extremes approaching -20°C, and Britain’s land suitable for arable farming could shrink from about a third to less than a tenth.
Not every model agrees, and that’s not reassuring. Some studies, including a 2025 analysis of 34 climate models, find the AMOC weakens but doesn’t fully collapse. But some scientists argue these models make the circulation too stable.
When some of the best evidence points to a one-in-four risk of a catastrophe, uncertainty is a reason for caution, not comfort.
