An ocean current system that helps regulate global climate could collapse after the year 2100, according to a new scientific study
The Atlantic Meridional Overturning Circulation (AMOC) is weakening and may shut down entirely in the next century if greenhouse gas emissions continue to stay high. This could lead to extreme winters in Europe, significant changes in rainfall patterns, and widespread climate disruptions worldwide.
The AMOC acts as a giant conveyor belt in the Atlantic Ocean. It moves warm tropical water northward near the surface and returns colder water southward at deeper levels. This circulation is an essential part of keeping parts of Europe relatively warm and in stabilising weather systems globally. However, the system is sensitive to changes in temperature and salinity, and current warming trends may be pushing it toward a critical tipping point.
New research highlights a long-term view
Most climate models used in earlier research stopped at the year 2100, but the latest study, published in Environmental Research Letters, extends simulations centuries further into the future.
Using data from CMIP6 climate models, scientists analysed scenarios through the years 2300 to 2500. In all nine high-emission cases, the models showed the AMOC entering a much weaker state or shutting down entirely. Some intermediate and even low-emission scenarios also resulted in collapse.
The research highlighted some of the most prominent tipping points. These included a collapse of deep convection in the Labrador, Irminger and Nordic Seas. Cold winters usually help cool the surface waters in these regions, allowing them to become dense enough to sink and mix with the deeper layers.
As the planet warms, the winter air is no longer cool enough to drive this process. The surface waters stay lighter, preventing the necessary vertical mixing. Once this feedback loop begins, the weakening of the AMOC becomes self-reinforcing.
A global chain reaction
A shutdown of the AMOC would have widespread effects. In Europe, winters could become harsher, while summers may become drier. Tropical regions could experience dramatic shifts in rainfall patterns, disrupting agriculture and water supplies. The overall impact would be a more chaotic and less predictable climate.
The heat released by the North Atlantic is essential for moderating temperatures and would drop significantly. In some models, it falls to less than 20% of current levels, and in extreme cases, it approaches nearly zero. This shift could trigger cascading effects across ecosystems, sea levels, and weather systems.
Clear early signs
Observations over the past decade in the North Atlantic’s deep convection zones show a downward trend in activity. While it remains unclear whether this is a result of natural variability or part of a longer-term decline, the data align with predictions from models.
One concern is that many standard climate models do not include meltwater from Greenland’s ice sheet, which would add even more fresh water to the North Atlantic, further making the AMOC even more vulnerable to collapse.
While it may already be too late to prevent an AMOC shutdown completely, scientists emphasise that reducing global emissions remains vital. Lower emissions would slow down the weakening and lower the chances of hitting the tipping point within this century. Immediate action could help preserve some stability in the Earth’s climate system for future generations.
