The Atlantic Meridional Overturning Circulation (AMOC) is a critical system of ocean currents located in the Atlantic Ocean. This immense loop of ocean currents plays a vital role in regulating climate across various regions by transporting warmer waters northward and colder waters southward. The health of the AMOC is essential, as its potential collapse could lead to significant global and regional climate impacts, including severe droughts and harsher winters, particularly affecting Northwestern Europe.
While previous studies have suggested a gradual weakening of the AMOC, there has been considerable uncertainty regarding the timing and possibility of its collapse under anticipated climate change conditions. However, new research published in the Journal of Geophysical Research: Oceans indicates that the collapse of the AMOC is increasingly likely and may occur sooner than previously thought.
The authors of this recent study employed an innovative physics-based indicator along with the Community Earth System Model (CESM) to simulate various scenarios of AMOC collapse. This new indicator is believed to provide a more accurate representation of water circulation compared to traditional parameters such as ocean surface temperature. Specifically, it identifies a tipping point marked by a change in surface buoyancy flux (Bflux) within a critical section of the North Atlantic Ocean, spanning from 40°N to 65°N.
The researchers analyzed 25 different climate models and discovered that the AMOC remained relatively stable until around 2020. However, recent data indicates signs of weakening. Under high-emission scenarios, their models predict the AMOC's collapse tipping point could occur as early as 2023 and as late as 2076, with a median tipping point projected for 2055. In more moderate scenarios, this tipping point ranges from 2026 to 2095, with a median of 2063.
If the AMOC were to begin collapsing, the transition to a significantly weakened state would take over 100 years. During this period, the climate in Northwestern Europe is expected to undergo drastic changes, including colder winters, decreased rainfall, and more intense winter storms. The study emphasizes that previous simulations often concluded around 2100; however, extending these models into the future could yield more accurate predictions.
The authors of the study advocate for climate modeling groups to extend their simulations to at least the year 2200 to better understand the risks associated with AMOC tipping under climate change. While there are limitations to this research—such as the exclusion of enhanced Greenland ice melt, which could expedite AMOC weakening—the findings underscore the need for immediate action.
Despite the grim outlook regarding the AMOC's stability, the study's authors stress that there is still an opportunity for societies to mitigate the impacts of a potential AMOC collapse by adopting low-emission scenarios and implementing urgent climate action. To safeguard against the risks of AMOC weakening, the global community must prioritize sustainable practices and innovative solutions to address climate change.
