The Atlantic Meridional Overturning Circulation (AMOC) is an amalgamation of ocean currents that act like a conveyor belt, transporting warm water from the tropics to the poles, and cooler water from the poles back towards the tropics. It’s a big part of the climate system and when AMOC slows down, or collapses, it has major implications for global climate.
Shutdown and Collapse
Last year a team led by Dr James Hansen published a study which showed that global warming had accelerated, and issued several major warnings. One of which stated that, “Shutdown of the Atlantic Meridional Overturning Circulation (AMOC) is likely within the next 20-30 years, unless actions are taken to reduce global warming.” This civilisation-shattering message never received the media attention it deserved.
More recently, in April 2026, new research was published in Science Advances by a team led by Valentin Portmann. Their research combined observations with models (some research relies only on models), and they predict an AMOC weakening of ~50% by 2100. An article by Damian Carrington in the Guardian, notes the prediction falls within a broader estimate of 42% to 58%, which Carrington says is, “a level almost certain to end in collapse.”
Carrington quotes one of the world’s leading AMOC specialists Professor Stefan Rahmstorf, who said that, “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.”
In effect, this would bring one of the world’s leading climate scientists (Dr James Hansen) and one of the world’s leading AMOC specialists (Professor Rahmstorf) onto the same page, with both of their forecasts now converging around the mid-century point. The primary difference being that Hansen forecasts a shutdown around that point, whereas Rahmstorf predicts the passing of a tipping point. Regardless of this difference, Rahmstorf believes the tipping point will lead to the eventual shutdown of AMOC.
When two of the leading experts begin warning of the shutdown of a critical part of the climate system in less than three decades, the world should listen closely.
If AMOC did collapse, what would the implications be?
Impacts of AMOC Shutdown
In the study led by Hansen, they note that the Earth is as warm as the Eemian interglacial – which was 120,000 years ago. In my review of their study from last year, I wrote that:
“During the late Eemian, the AMOC shutdown which had a massive effect on the climate. AMOC transports the equivalent of 1,000 trillion watts of heat from the South to the North. As a result of the shutdown, much of the heat remained in the Southern Ocean, where it may have played a role in collapsing the West Antarctic ice sheet. This would explain why this period saw several meters of sea level rise within a single century. The West Antarctic ice sheet is particularly vulnerable as it juts into the sea and rests on bedrock that lies hundreds of meters below the water line. Therefore, as oceans warm, this ice sheet starts melting at the base and is susceptible to rapid disintegration.
The study spoke about AMOC shutdown being a “Point of No Return.” Tied very close to this (as explained above) is the related “Point of No Return” of the collapse of the West Antarctic ice sheet. This would lead to several meters of sea level rise. What would happen if the West Antarctic ice sheet collapses?
More than half the world’s largest cities would be submerged, as would large parts of the US, China, Bangladesh, the Netherlands, and island nations. Largescale emigration would ensue as people flee coastal areas and disaster zones. Sea levels won’t stabilise after the collapse of the West Antarctic ice sheet. This is because Greenland and Antarctica have a lot of ice in contact with warming seas – enough to raise sea levels by 15-25m. During the early Pliocene – a comparable time in Earth’s history when temperatures were 2C warmer than pre-industrial times (bear in mind we’re heading for around 2.7C of warming this century) – sea level was 15-25m higher. Hansen’s team say that, “Sea level change takes time, so coastlines would be continually retreating.” A major uncertainty is the point at which ice shelf melting must reach, before the collapse of the ice sheet becomes unavoidable.”
In a separate Guardian article, George Monbiot warns of impacts including:
- A massive effect on precipitation in the Amazon rainforest, with a potential for the dry season to switch to the wet season, and for the wet season to switch to the dry season, which could have a disastrous impact on the entire ecosystem, potentially leading to a cascade of further tipping points.
- Some European cities in Northwestern Europe could see a temperature drop of 5C – 15C.
- Sea level rise may speed up along the eastern coast of the US.
Researchers published an article in Communications Earth & Environment, stating that an AMOC collapse would cause an increase in CO2 levels of around 47–83 ppm (for context, we’re at 430ppm at the time of writing and the safe limit is 350ppm). This in turn could worsen the climate emergency by causing a further 0.2 °C of warming.
Carbon Brief says that global monsoons may also be affected (impacting up to half the world’s population), and the Sahel could see worsening drought. They go on to say that arable farming may no longer be possible in the UK.
To put it bluntly, a research article in Science Advances makes it clear that, “no realistic adaptation measures can deal with such rapid temperature changes under an AMOC collapse.”
A route forward?
It’s terrifying that science suggests an AMOC shutdown is potentially on the cards in the next few decades. Our world would be radically reshaped if or when such an event plays out.
Far right leaders in Europe, and those relentlessly hammering the immigration drum may want to adjust their tune; for if an AMOC collapse does occur, then there is likely to be reverse migration out of Northwestern Europe into more liveable regions of the globe. All those stirring up anti-immigration sentiment, may find themselves (or their descendants), as immigrants in the future. That’s a genuine possibility we’re living with now.
The big structural changes that we need to tackle the climate emergency must be implemented by political leaders. But, after no fewer than 30 annual COP climate summits, where leaders have failed to address the climate crisis, one may begin to lose hope that this will be achieved. Yes, the world has come together once before to tackle a global issue in the form of the hole in the Ozone layer – one of the most remarkable success stories, which produced “the most successful multinational environmental agreement.”
But the climate crisis is being bankrolled by the fossil fuel industry who’ve also lined the pockets of some key decision-makers. Not to mention how some media barons have purposely pulled the wool over their readership’s eyes. In my view, the chance of achieving a political breakthrough seems unlikely, otherwise we’d have an internationally binding agreement by now.
As I’ve mentioned in recent blog posts (here and here), I believe what the world needs to navigate this perilous century is a switch away from representative democracy (where we elect politicians by voting) towards a form of participatory democracy, whereby citizens become decision-makers through processes such as citizens’ assemblies, citizens’ juries, and participatory budgeting. There are a growing number of proposals showing how these processes could become permanent and thus put citizens back in charge of determining our collective futures, as opposed to letting corporations push us over the cliff edge.
The polycrisis is here, and our problems mount with each passing day of global inaction. A major transformation is needed to put humanity onto a new trajectory. I believe that one of the few ways this may happen is through participatory democracy, because citizens have shown throughout history (going all the way back to Ancient Greece) that we can be the authors of our own future. Where politicians might prioritise corporate interests at society’s collective expense, citizens in their place wouldn’t vote for our collective downfall.
It’s a hell of a lot to ask society to reshape global governance at the drop of a dime, all whilst we need to urgently tackle the climate emergency, the AI crisis, and the wider polycrisis. But it’s primarily because global governance has failed to address these major issues and shows no sign of being able to do so, that I feel things must change – and change in our favour. If we can make that happen, then we may just slip through the closing sliver of a gap that remains to undo our colossal damage to the world, and have a shot at a decent and liveable future.
I’ve been writing about the climate emergency since 2016, and the AI crisis since 2023. I write all my own work, without the use of AI. I don’t publish on any other paid platforms, and my blog remains completely free to read. If you’ve found my writing informative and if you’d like to support my work, I’d be really grateful if you did so here. Thank you.
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