Iceland has raised the risk of a collapse of the Atlantic Meridional Overturning Circulation (AMOC). The Ministry of Environment, Energy and Climate informed the National Security Council that the slowdown of this ocean current represents a existential and security threat, an unprecedented measure that, according to Reuters, will allow all ministries to coordinate in this scenario.
The decision comes after new evidence of weakening of the AMOC and warnings from the scientific community. Recent reports maintain that the probability of collapse has increased and can no longer be treated as an improbable event, although experts emphasize that There is no consensus regarding its imminence, its irreversible nature, or its transitory nature.
What is AMOC and why does it support the European climate?
The AMOC is a great ocean-going machine that transports warm waters towards the North Atlantic At the surface, it rises and returns cooler, denser water to the depths southward. This exchange regulates the climate of the Northern Hemisphere and largely explains... the mildest winters in Europe compared to other regions at the same latitude.
Ocean warming and the influx of freshwater from the Greenland ice melt and increased precipitation in the Arctic They reduce the salinity and density of the surface water, hindering the sinking that feeds the system. As oceanographer Cheng Lijing pointed out, when the surface warms up, The heat penetrates deeper layers and the currents are altered.
This circulation is not a minor detail of the climate: several studies have linked cold phases in the North Atlantic with a slower AMOCAnd an open letter signed by specialists in 2024 warned that the system It could be approaching a turning pointEven so, researchers like Dorthe Dahl-Jensen urge caution and more observation time before drawing definitive conclusions.
Signs of weakening and what science says
Observations since the mid-20th century point to a slowdown of around 15% Compared to previous levels, this pattern is consistent with global warming. Recent analyses have identified a possible “fingerprint” of the AMOC slowdown, including a anomalous warming in the depths of the equatorial Atlantic, which reinforces the diagnosis of weakening.
A study published in 2025 in Environmental Research Letters concludes that the probability of collapse has increased and already should not be considered remoteOther studies have proposed broad timeframes for a possible shutdown, from the coming decades to the end of the century, but several experts—such as Carlos Duarte—emphasize that There is no robust evidence of immediate climate impacts attributable to a collapse already underway.
The scientific community agrees on one point: the system is weakeningHowever, significant uncertainties remain regarding the when and how. This combination of signals and doubts is what has led North Atlantic governments to prioritize surveillance, investigation and preparedness.
Potential impacts in Europe and Spain
Increased local cooling in the North Atlantic could translate into changes in the trajectory and intensity of winter storms which reach Europe, with more extreme episodes according to scientific literature. In parallel, the global thermal readjustment caused by a slower AMOC may alter rainfall patterns in different regions of the planet.
For the European continent, several lines of research consider the risk of harsher winters in the north and an increase in climate variability. In southwestern Europe, including the Iberian Peninsula, experts are studying potential effects on rainfall, droughts and seasonality, with implications for sectors such as agriculture, energy or fishing, although a precise quantification cannot yet be detailed.
The level of risk demands caution. Scientists like Stefan Rahmstorf warn that the point of no return It could be closer than expected if emissions continue, while other teams, such as those led by Dahl-Jensen, are calling for longer observation periods before projecting drastic scenarios. uncertainty It is not synonymous with security: it is a call to strengthen preparedness.
The political response: from Iceland to the rest of Europe
Iceland has been the first country to classify the AMOC risk as national security issueThis decision empowers inter-ministerial coordination, the activation of emergency plans, and the evaluation of measures such as strategic reserves food and fuel supplies, modernization of critical infrastructure, and logistical reinforcement in the face of extreme events.
In October, Reykjavik hosted more than 60 experts to assess the social impacts of a potential collapse. Meanwhile, countries such as the UK and Norway have increased funding to investigate points of no return and improve early warning systems. In the Nordic countries, the debate has become a key part of ministerial agendas, raising the bar for climate preparedness.
What to watch out for from now on
The priorities include improving the monitoring of salinity and density In the North Atlantic, strengthen the networks of buoys and observatories, and develop models that integrate early signs of changes in deep-water formation. Furthermore, Europe is studying how to adapt energy, agriculture, and water management plans to a more variable climate.
With the AMOC losing momentum and a range of scenarios open, the European region—including Spain—faces the challenge of Prepare without alarmismto accelerate emissions reductions and strengthen resilience. Available evidence suggests that the risk is increasing, while the exact timing and magnitude remain uncertain—a balance that demands prudence, science, and planning.