Sixth episode. The voice of science. We listen to the ocean.
In the Heroes of the Undercurrent series, we speak with the people driving the sustainability transition from within. In the previous episode, we spoke with Wim Thiery, professor of climate science at the Vrije Universiteit Brussel, about a climate on steroids, about CO₂ as the PFAS of the atmosphere, about intergenerational injustice. He closed with a sentence that lingered: 'We are sending our children into a Terra Incognita that will be more extreme and brutal than anything we have known.'
Now we speak with René van Westen. Postdoctoral researcher in climate physics at the IMAU, Utrecht University, and lead author of the most-cited climate paper of 2024. The man who, for the first time in a modern, complex climate model, demonstrated that the Atlantic overturning circulation is genuinely on course towards a tipping point. It earned him more than thirty interviews in three weeks. CNN, The Guardian, BBC. Not because he raised the alarm, but because his physics spoke.
The conversation began quietly. And stayed that way. The content was anything but.
Madrid lies on the same latitude as New York. Anyone hearing that for the first time doesn't believe it. New York has harsh winters. Madrid does not. The difference has one name: the AMOC, the Atlantic Meridional Overturning Circulation, also known as the Gulf Stream. The Netherlands lies on the same latitude as the south of Canada. Without the AMOC, Amsterdam would have the climate of Calgary.
The AMOC is a vast transport system in the Atlantic Ocean. Warm surface water flows northward from the Caribbean and the Gulf of Mexico along the coasts of Europe, releases heat into the atmosphere, and then sinks in the North Atlantic Ocean, made heavier by salt and cold, before returning southward through the deep sea. A millions-of-years-old system that makes Europe's climate roughly eight to ten degrees warmer than it would otherwise be. It also governs the rainy season in West Africa, the Asian monsoon, and rainfall over the Amazon. 'It is a global shift if this collapses,' van Westen said in international media. 'Not a European cold snap.'
That system is now in danger. What is remarkable about van Westen's discovery is not that the danger exists. What is remarkable is that he was the first to demonstrate how that danger looks, when it becomes measurable, and how quickly things move once it does.
In public perception, climate change is a line: it gets warmer, seas rise, harvests become erratic. A steady, manageable slope. That picture is only partly correct, van Westen explains. So far, the climate change we observe is largely linear, and that creates a false sense of predictability.
“The climate change we have seen so far is still relatively linear. That is still something people can understand. But we are heading towards a world where we will be dealing with non-linear climate change. And that is where the tipping points come around the corner.”
The climate system is a system in balance. Over the past 100,000 years, during a different background state, namely the ice age, the AMOC has shifted between equilibrium states many times. These are known as the Dansgaard-Oeschger cycles. The last time the AMOC weakened significantly was due to the draining of enormous North American meltwater lakes, an event known as the Younger Dryas. The relatively strong AMOC state we have today has persisted for around 10,000 years. This stable state kept Europe hospitable and helped give rise to modern society on the continent. And within such a system, tipping points can exist: the moment at which a subsystem has moved so far out of balance that it cannot return to its previous state. Not on human timescales, not on any timescale relevant to us. The ice on Greenland. The permafrost. The coral reefs. And the AMOC. All systems that can absorb a certain amount of disruption, but that tip irreversibly once a threshold is crossed.
The danger of the linear picture is precisely this: when something appears to be changing gradually, we assume we can see it coming and manage it. Tipping points do not always announce themselves. They surprise.
In February 2024, van Westen published a paper in Science Advances that he describes with characteristic understatement as an answer to a question science had been trying to answer for twenty years. For the first time, his team succeeded in simulating a full AMOC tipping point in a modern, complex climate model. Four thousand model years of computing time. A measurable, physics-based early warning signal. The conclusion: the AMOC is on course towards that tipping point.
His follow-up research, published in August 2025, brought the percentages and timelines. Under a moderate emissions scenario, the middle-of-the-road path, the probability of reaching the tipping point before 2100 is already more than fifty percent. Under a high-emissions scenario: more than ninety percent. Both scenarios place the tipping point on average around 2060. These probabilities emerge from an analysis in which not one but twenty-five different climate models were examined. The answer that came out made him genuinely frightened for the first time.
Van Westen recalls the moment himself:
“For the first time, I lay awake because of my own research. We always work with one climate model, but when I ran an analysis across twenty-five climate models, the same answer came back: the tipping point as early as 2060. That is hopefully still within my lifetime. And that was the first time I was truly shocked. This is no longer one rogue model showing this. All the climate models are showing this.”
After that, he watched his international colleagues publishing the same findings one by one. The science is beginning to converge. There is still debate, he adds honestly, but the direction is clear.
There is something curious about how people handle statistical risk. A one-in-two chance of something catastrophic sounds, as an abstract number in a scientific report, manageable.
If the probability of a plane crashing were fifty percent, would you still board it? Van Westen immediately recognises the paradox. He refers to Carl Sagan, who made a similar argument in the nineties about US defence spending during the Cold War:
“Carl Sagan once spoke before Congress and said: do you know how much the US spent on defence during the Cold War? Ten trillion dollars. With that amount you could have bought almost everything in America, except the land itself. What justifies that kind of expenditure? You need to be resilient. Was there a hundred percent chance that Russia would attack? No, because the Russians never attacked America. But a certain probability apparently justifies an investment of ten trillion dollars. Why does that logic stop when it comes to climate change?”
And then there is a deeper reason why urgency fails to land. Van Westen names it plainly:
Put bluntly: there is no immediate reason to die from climate change tomorrow. The world simply carries on. And so we keep putting it off.
We keep passing that bill on. And the next generation pays it. It makes climate measures fundamentally unpopular: the pain is now, the benefits lie in a future that falls outside the planning horizon of most decision-makers.
In public discussion about the AMOC, almost everything revolves around one thing: temperature. Europe gets colder. But van Westen makes clear that the temperature drop is only one of the consequences, and not even the most significant.
His research into European temperature extremes, published in June 2025, paints a picture that goes far beyond degrees. In moderate scenarios: sea ice reaching the Wadden Sea. In heavier scenarios: as far as the coasts of England and Scotland. Winter temperatures in Oslo that could drop to -48 degrees Celsius. At the same time: a drying climate, rainfall deficits and rising sea levels along the Atlantic coasts.
But it is the impact on agriculture that is most directly relevant to the F&B world. Research published in Nature Food already showed that AMOC collapse would hit UK farming an order of magnitude harder than climate change alone, with complete cessation of arable farming as a realistic scenario. Shorter growing seasons, more late frosts, drier summers. Comparable effects are to be expected in the Netherlands, northern Germany and northern France. Van Westen names the Netherlands explicitly:
“The Netherlands is the second largest food exporter in the world, the largest per unit of land area. That is already quite remarkable when you think about it. But imagine that you suddenly have to farm that land far less efficiently. Then it genuinely starts to become a security risk. And because the Netherlands is such a major food exporter, the impact would be felt worldwide.”
He draws the geopolitical comparison with the conflict in Ukraine:
“Look at Ukraine: one major agricultural producer in trouble, and grain prices shot up worldwide. In a globalised society, what happens somewhere you’ve never heard of can have a direct impact on your own wallet. Northwest Europe is crucial for agricultural products. If that goes, it will ripple across the entire world.”
On top of that, an AMOC collapse would fundamentally disrupt global rainfall patterns. West and Central Africa would receive drastically less rain. The Asian monsoon, the lifeblood of rice, wheat and soy for billions of people, would be disrupted. Central America would dry out further. The sourcing of raw materials from these regions, the production facilities in Northern Europe, the logistical infrastructure in low-lying coastal areas: these are not abstract vulnerabilities. These are concrete positions in a supply chain exposed to genuine systemic risk.
There is something else van Westen raises, something uncomfortable for his own field. The climate models used by the IPCC are systematically too optimistic about the stability of the AMOC. They assume the tipping point lies around four degrees of warming. But his own research shows it could occur at just 2.5 degrees, and even that figure may be too high, because other processes are not being adequately captured.
“The climate models portray the AMOC as far more stable than it actually is. Those models assume a tipping point around four degrees of warming, but the real threshold is probably much lower.”
The policies we are pursuing are partly based on models that are too slow to see tipping points coming. The most recent IPCC report from 2021 simply did not yet have access to the indicators van Westen now has. The next report is currently being written, but policy has been running on those outdated insights for years.
Could it turn out better than expected? Yes, he admits honestly. There is a range of uncertainty. But that range also runs upward. Uncertainty is no reason for reassurance.
Wim Thiery referred earlier in this series to intergenerational injustice: the idea that the generation writing the climate bill is not the same generation that will pay it.
Van Westen has a one-year-old son. He mentions him himself, almost in passing, but it is anything but that: I was genuinely shocked. My parents won't live to see this. But we are the transition generation, the ones who suddenly realise what is at stake. I happen to have a one-year-old. He is going to grow up right in the middle of it. And all the generations that come after him, that is what I worry about.
It is the only moment in the conversation where the composure briefly slips. Not for drama. For the simple, undeniable honesty of a father who knows what he knows.
There is a pattern that frustrates van Westen, though he remains calm about it. Major systemic shocks, a war in Ukraine driving up gas prices, COVID turning remote work from impossible to normal overnight, move people with extraordinary speed. Climate does not.
“You spend years running campaigns telling people: don’t set your thermostat to 21 degrees, switch it to 20. That campaign ad doesn’t land. And then you have the Ukraine-Russia conflict, gas prices rise, and suddenly everyone can switch en masse to 16 degrees, because it hurts financially. People respond very strongly to financial triggers.”
The same logic applies to heat pumps and solar panels: unpopular until energy prices exploded, and now suddenly in demand again as geopolitical pressure mounts.
“It is a bit strange that you need a major systemic shock every single time before people start moving. The same thing happened with COVID: working from home was impossible, and then suddenly it wasn’t.”
The problem with the path of gradual change, the political choice for minimal pain, incremental measures and broad support, is that it does not move the broad middle. And the middle is precisely what you need.
“People simply don’t want to give up their comfort and their freedoms. And that means you can’t bring along the broad middle, the people who do care about climate change but still feel: I find it hard to make different choices, partly because they are not being motivated to.”
His conclusion is clear: governments need to take a leading role, even if that is unpopular. Not through campaign ads, but through instruments that force real choices. Taxes that pass on the true cost of pollution, price incentives that make sustainable options more attractive than polluting alternatives.
And there is a positive mirror image of the negative tipping points he models. Once the broad middle starts moving, the transition can happen at extraordinary speed. He points to Norway: You also see: once people engage with the transition, things move fast. You can see that in Norway, where the entire vehicle fleet was fully electrified within ten years. It can be done.
For our sector, the implications are concrete and immediate.
Under moderate climate policy, the probability of reaching the AMOC tipping point before 2100 is already more than fifty percent. No insurance model, no IPCC mainline takes this seriously into account. Yet the physical risks are real and accumulating on multiple levels at once. The sourcing of raw materials from West Africa, Central America and Asia; production facilities in Northern Europe; logistical infrastructure in low-lying coastal areas: these are concrete positions in a supply chain exposed to genuine systemic risk.
What is the course of action? Van Westen is clear: every fraction of warming we prevent reduces the probability of reaching the tipping point. The rate of warming is the critical factor, because the slower we warm, the more time the system has. Every reduction counts, and there is no threshold below which action becomes pointless.
For the sector, this means two things. First: diversify the supplier portfolio away from climate-vulnerable regions now, and bring the AMOC risk into the boardroom. Not as a sustainability agenda item, but as strategic business risk. Second: use the leverage the sector has in its hands every day. Van Westen cites Fork Ranger:
“Every day you have three opportunities to choose a sustainable or a non-sustainable option. If everyone were to eat one day less meat per week than they currently do, that alone would have an enormous positive impact.”
On pricing structures, the picture is clear: the price difference between meat and plant-based options is partly artificial. Products are kept artificially cheap through subsidies and uncounted external costs. But there is something else at play: volume. The meat supply chain has been optimised at scale over decades, and that is reflected in the price. Plant-based alternatives have not yet reached that scale. Solar panels were unaffordable in 1980 and are now 99 percent cheaper, not because the technology changed, but because volume exploded. The same mechanism applies here. Collaboration across the supply chain, between buyers, producers and retailers, is the lever to create that volume and structurally drive down the price of the better alternative. Government policy that sets the right incentives accelerates that process. But the supply chain itself can start now.
Van Westen endorses the direction:
“You are making a more sustainable choice that is also much better, both for the planet and for yourself. That is exactly what you want to encourage. Then you reduce the tax on it, and people will probably start choosing it.”
At the end of the conversation, I wait for the dark conclusion. It does not come.
Van Westen describes himself as 'originally an optimist by nature.' His research has made him more pessimistic, he admits honestly. But he does not end in fatalism. Because the calculations also run the other way:
“If we limit warming to three degrees, that probability already drops to 57 percent. That is already a significant reduction in risk. If we limit warming, the risk also keeps getting smaller.”
And there is one more recent insight, from ongoing research: it is not the absolute temperature of warming that determines whether the AMOC collapses, but the rate of warming. The faster we warm, the greater the risk. The slower, the more time the system has to adapt. Every delay counts. A preprint is already publicly available.
Science has answers. The technology is there. Solar panels have become dramatically cheaper. The Norwegian vehicle fleet electrified in ten years. What is missing is, in the words of Wim Thiery the week before, the collective will. Van Westen agrees without hesitation:
“In principle, the technology is there. The only thing that is missing is bringing the mass of people along.”
He says it without pathos. Like a physicist solving an equation.
The ocean current has flowed for millions of years. It carries warmth. It carries life. It keeps a continent habitable. It is now measurably out of balance. The question van Westen puts to us is the same question his one-year-old son will ask one day: what did you know, and what did you do about it?
We know. Now.
This interview is part of the Heroes of the Undercurrent series by Conceptional. Previous episodes: Manon van Leeuwen, Debbie Rooms (Compass Group Netherlands), Inge van Baardwijk (Royal Schiphol Group), Inan Şahin (Efteling) and Wim Thiery (VUB). René van Westen is a postdoctoral researcher in climate physics at the IMAU, Utrecht University, and lead author of the paper 'Physics-based early warning signal shows that AMOC is on tipping course' (Science Advances, 2024). The article was submitted to van Westen for approval prior to publication.
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