🌍 Towards a sudden tipping of the AMOC: latest forecasts are alarming

The oceans quietly shape Earth's climate. Behind this immense mechanism, one particular current draws researchers' attention: the AMOC, whose future now appears threatened.

Scientists are observing with concern the evolution of this system, which has regulated heat distribution between hemispheres for millennia. Recent analyses predict that its weakening could lead to a complete collapse, with major consequences for Europe, but also for America as well as northern Asia and northern Africa.

A climate engine under pressure

The AMOC functions like a giant conveyor belt that transports heat to the North Atlantic, before sending cooled waters back south. This circulation acts as a climate regulator for Europe, mitigating the severity of winters. Without this mechanism, the continent's northwest would experience much harsher conditions.

This system relies on water density, influenced by its salinity and temperature. The increasing freshwater input from Greenland's melting reduces this density, making surface water less able to sink. This change disrupts the entire circulation.

Climate simulations reveal that the probability of a major weakening increases significantly with greenhouse gas emissions. Even in more moderate scenarios, the slowing trend persists, indicating structural vulnerability.

A disrupted climate future

Projections up to 2500 indicate that total collapse of the current would become very likely if emissions are not rapidly reduced. Researchers estimate that the tipping point, once reached, would make the process irreversible. Specifically, the latest forecasts announce that collapse should begin around 2100, with a very clear weakening of the current between 2100 and 2500.

Europe would be on the front line. Winters would become colder and storms more intense due to a destabilized jet stream. Summers, however, would remain marked by heatwaves, accentuating seasonal contrasts.

Globally, the impact would extend to the displacement of tropical rainfall zones and a sea level rise that could reach 50 centimeters (about 20 inches). The ocean would also absorb less carbon dioxide, worsening global warming.

To go further: why do we talk about climate tipping points?

A "climate tipping point" refers to a critical threshold beyond which an Earth system changes abruptly and irreversibly. Unlike gradual evolution, this type of tipping is characterized by sudden transformation, comparable to a switch turning from "on" to "off". In the case of the AMOC, this means that gradual slowing could suddenly turn into total collapse, durably disrupting the climate balance of the North Atlantic.

These tipping points are feared because they involve changes impossible to reverse on a human timescale. Once crossed, the effects self-perpetuate and reinforce themselves: the disappearance of part of the sea ice, for example, further accelerates ocean warming by reducing the reflective effect of ice. For the AMOC, the massive freshwater input from Greenland's melting weakens ocean water density, which decreases the sinking of cold waters and ultimately threatens the entire mechanism.

The concept of tipping points doesn't only concern oceans: it's also studied for ice sheets, tropical forests, and Arctic permafrost. These elements of the global climate function as interconnected balances. If one tips, it can drag other systems into a cascade of transformations, making the global climate even more unstable and unpredictable.