The Atlantic meridional overturning circulation (Amoc), a crucial system of currents influencing the global climate, is unlikely to completely collapse within this century, according to a recent study. However, scientists emphasize that a significant weakening of the Amoc remains probable, which could still have disastrous impacts on billions worldwide.
The Amoc is a complex oceanic system responsible for transporting warm, salty water northwards towards the Arctic, where it cools, sinks, and flows back southwards. This circulation is vital for maintaining climate stability across the globe. Unfortunately, the ongoing climate crisis is weakening this system, prompting concerns about when and if it might collapse.
Recent studies based on ocean measurements reveal that the Amoc is becoming unstable and approaching a critical tipping point beyond which a collapse would be unavoidable. Although some research suggests this might occur this century, these predictions face uncertainties due to limited direct data. Climate models, however, project that a complete collapse is unlikely before 2100, though they may underestimate the system's actual instability.
The latest study, published in the journal Nature, offers new insights by utilizing climate models to examine the factors contributing to Amoc's relative stability. It highlights the role of winds in the Southern Ocean, which continue to draw water to the surface, sustaining the system's circulation.
Despite the reassurance that an abrupt Amoc collapse is improbable within this century, Dr. Jonathan Baker from the UK’s Met Office warns that Amoc weakening would still pose significant climate challenges. This includes increased flooding, droughts, and accelerated sea level rise, necessitating urgent reductions in greenhouse gas emissions.
Prof. Niklas Boers from the Potsdam Institute for Climate Impact Research emphasizes that even without a tipping point-induced collapse, a severe weakening of Amoc could have severe effects on tropical rainfall patterns. A reduction in Amoc strength by even 50% could drastically alter regional and global climates, underscoring the critical need for climate action.
The study's findings reveal new downwelling areas in the Pacific and Indian Oceans, which partially balance the slowing Amoc. However, these regions alone cannot compensate for the weakening, highlighting the need for improved observations and modeling in these areas to enhance future projections.
Prof. Stefan Rahmstorf, an expert on Amoc, notes that while the study provides valuable insights into wind-driven aspects of Amoc, it does not alter the assessment of risks associated with human-caused global warming. His ongoing research suggests that a post-2100 Amoc collapse can no longer be considered a low-probability event.
In conclusion, while the latest study provides crucial insights into Amoc stability, the extent and timing of future weakening remain uncertain. Ongoing research and improved climate models are essential for better informing policymakers and mitigating potential impacts on global climate and society.
