Collapse of the AMOC : "Icelanders are accustomed to living with powerful natural forces. However..."
Is winter coming ?
Welcome to 420ppm, a newsletter dedicated to overshoot politics. Below is an interview with Iceland’s Minister for the Environment, Energy and Climate discussing why the Atlantic Meridional Overturning Circulation (AMOC) has been classified as a national security risk. 420ppm is primarily a French publication, but some of our interviews and articles are also published in English.
Hi there,
In November, we learned that Iceland is now considering the collapse of the Atlantic Meridional Overturning Circulation (AMOC) a threat to its national security. This announcement is the culmination of a series of warnings about the state of this system of ocean currents that organizes heat flows between the two hemispheres.
For a long time, the scientific consensus was rather reassuring about this critical tipping point of the Earth system. But in recent years, many researchers have come to believe that this risk has been underestimated. They fear that disruptions linked to global warming—in particular the melting of the Greenland ice sheet and changes in precipitation patterns—could disrupt the movement of these water masses.
In the event of a weakening or even a shutdown of this phenomenon, temperatures would drop drastically across a large part of Europe and in the Nordic countries. It wouldn’t be quite like in The Day After Tomorrow, but it still wouldn’t be fun. To better understand how Iceland is approaching this catastrophic scenario, I reached out by email to its Minister of the Environment, Energy and Climate, Jóhann Páll Jóhannsson ◇
Iceland has classified the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC) as a national security and existential risk. What does this designation mean in practical terms?
Jóhann Páll Jóhannsson For me, classifying the potential collapse of the AMOC as a national security and existential risk is about recognising that we are no longer dealing with a distant or abstract environmental issue. It means acknowledging that this is a systemic risk with the potential to undermine the foundations of our society: our food systems, our energy security, our infrastructure, our economy and, ultimately, our ability to live safely in this country.
In practical terms, elevating this issue to the National Security Council ensures that it is addressed with the seriousness it warrants. It enables us to bring together all the relevant ministries and institutions, not only those responsible for environment or climate issues, but also civil protection, energy, transport, food security and foreign affairs. It enables long-term risk assessment, preparedness planning and coordination across government systems, rather than fragmented or short-term responses.
Most importantly, it reflects a shift in how we govern climate risk. When a risk is potentially irreversible on a human timescale and carries catastrophic consequences, uncertainty is not a reason for inaction. It is precisely the reason to act early, transparently and decisively.
Why does a potential weakening of the AMOC represent such a serious threat to Iceland?
Iceland’s vulnerability is rooted in geography and physics. We are an island nation in the North Atlantic, and our climate, ecosystems and economy are deeply shaped by ocean circulation, including the AMOC. This circulation system is a core regulator of temperature, precipitation and storm patterns in our region. Scientific evidence indicates that the AMOC has distinct stability thresholds, often referred to as a tipping point. Once crossed, changes can become abrupt and effectively irreversible on a human timescale. Recent research extending beyond 2100 shows that under continued high emissions, a gradual weakening this century can commit the system to collapse later on. Crucially, newer studies suggest that this loss of stability may occur at global warming levels closer to 2.5 °C — a level the world is currently heading toward.
We do not yet have detailed national modelling that translates an AMOC collapse into precise temperature figures or sector-by-sector impacts for Iceland. That work is still needed. However, what we do know is that the impacts could be profound: a much colder and more volatile climate, altered precipitation patterns, more extreme storms, sea ice affecting marine transport, and severe disruption to fisheries, agriculture, energy systems and infrastructure.
The time horizon is not only about when the impacts would be fully realised, but about when we may cross the tipping point that commits us to those outcomes. That could occur within the coming decades, even if the most severe consequences unfold later. From a risk-management perspective, that distinction is critical.
Is adaptation to such changes conceivable? What contingency or emergency measures could realistically be put in place?
I want to be honest about the limits of adaptation. Icelanders are accustomed to living with powerful natural forces, and our society has demonstrated resilience in the face of earthquakes, volcanic eruptions and extreme weather. However, unlike many of those an AMOC collapse would not be a temporary shock. It would represent a long-lasting structural change to our climate system.
Some level of adaptation and preparedness is both necessary and possible. That is why we are developing a comprehensive natural disaster preparedness policy, to be finalised by 2028, and why we are assessing what additional research and planning is required. This includes examining whether specific AMOC-related contingency plans should be developed. At this stage, no options are ruled out.
At the same time, we must be clear that there is a real risk of reaching conditions by which adaptation will be either extremely costly or simply not feasible. That is why prevention by reducing emission and mitigating climate change, reducing the likelihood of collapse, must remain our primary objective. Preparedness can reduce harm, but it cannot fully compensate for the destabilisation of a core Earth-system regulator.
How can Iceland act to prevent this threat? Global warming is largely driven by countries far from Iceland, many of which may not perceive the collapse of the AMOC as an immediate concern. Why would they agree to make radical emissions cuts?
It is true that Iceland’s own emissions are small in global terms. But climate risk is not allocated according to responsibility alone; it is shared through interconnected systems. The AMOC does not respond to national borders
Preventing this threat ultimately means addressing its root cause: rising global temperatures driven by greenhouse gas emissions. Iceland must continue to reduce its own emissions, transition its energy systems, and invest in climate solutions. Equally important, we must act internationally, through diplomacy, cooperation and by example, to argue that emissions reductions are not just an environmental goal, but a matter of global stability and security.
The science is now clear that emissions pathways materially affect the probability of catastrophic outcomes. Even if we cannot eliminate risk entirely, reducing warming reduces the likelihood of crossing irreversible thresholds. That is a compelling argument for all countries, including those that may not initially perceive AMOC collapse as their problem. While the AMOC may appear geographically distant, its weakening or collapse would have far-reaching consequences across continents, through food systems, economic disruption and geopolitical instability. By stalling the heat transport northward, causing climate in the Arctic region to cool, the cooling mechanisms of southward bound ocean currents would also stall, increasing warming near the equator, and thus an AMOC collapse would have further reaching consequences than just in Iceland, or the Nordic countries.
Iceland’s approach is to highlight these systemic risks, contribute constructively to international climate action, and encourage global commitment to emissions reductions as a matter of long-term global stability and security.
You hope to move climate tipping-point risks from the margins of scientific debate into the mainstream of global policy and security planning. How can this be achieved in a world where international cooperation appears to be weakening?
I believe the first step is honesty. Governments must speak openly about tipping-point risks and stop treating them as speculative or marginal. By bringing the AMOC explicitly into national security discussions, Iceland is doing exactly that. Moving these risks into the mainstream requires linking scientific insight with decision-making: early warning, scenario analysis, and assessment of first-, second- and third-order impacts. This is not about predicting the future with certainty. It is about identifying vulnerabilities and ensuring that institutions are prepared to respond.
Even in a fragmented international landscape, there is growing recognition across Europe that systemic climate risks require a specific governance approach. AMOC-related risks are increasingly appearing in strategic foresight, defence-linked climate analysis and resilience planning. Iceland engages with its neighbours and partners through existing Nordic, European and international frameworks on climate science, security and preparedness, even as formal AMOC-specific security coordination remains limited at present. One of my main focuses at COP30 was to discuss this with other heads of state and government representatives, and in my plenary speech I chose to focus on this issue.
Through ARIA, the United Kingdom is funding efforts to monitor and model climate tipping points and to develop early-warning systems. Would Iceland be willing to contribute to or help develop such tools? What signals or thresholds would trigger emergency planning or policy escalation?
I am familiar with ARIA and representatives from my Ministry have already met with them to learn about their operations. It is an interesting initiative and large-scale research initiatives like these are very important.
As I’ve said, in Iceland, an assessment of further research needs is ongoing, and monitoring and preparedness are already recognised priorities within our national security and civil protection framework. I see monitoring, modelling and early-warning systems as essential components of responsible governance in an era of systemic climate risk and have expressed Iceland’s general openness to contributing to, cooperating or engaging with such efforts.
At present, specific thresholds that would trigger emergency planning or policy escalation are not mature enough to discuss. However, we are aware that given the nature of tipping points, waiting for a single definitive signal would be dangerous. Escalation is more likely to be based on converging lines of evidence: sustained weakening trends, changes in freshwater input and stratification, and indicators of declining system stability.
Our approach is precautionary. When the potential consequences are catastrophic and irreversible, governance must be willing to act on risk, not certainty.
What is your position on geoengineering approaches, particularly stratospheric aerosol injection? Would Iceland consider participating in the deployment of solar geoengineering if it appeared to be the only way to limit temperature overshoot?
Iceland’s focus remains on emissions reductions, prevention of tipping points, and adaptation to unavoidable impacts.
That said, I recognise that as risks escalate, societies will increasingly debate options that were once considered unthinkable. Any discussion of interventions with planetary-scale consequences must be approached with extreme caution, robust scientific scrutiny and, above all, democratic oversight. Bringing climate risks into formal security and governance structures is part of ensuring that these decisions, if they ever arise, are subject to public scrutiny and democratic control ◆