The Day After Tomorrow talk re-emerges – Is the AMOC Really Set to Collapse, Or Is It All Hype?

Much-loved by film goers and much-maligned by scientists, the Day After Tomorrow is a disaster movie that dramatised (with a lot of poetic licence) what could happen if a current in the Atlantic – the Atlantic Meridional Overturning Circulation (AMOC) – suddenly stopped and tipped the world into a big freeze.

At the time, the movie was largely dismissed by climate scientists, but now, as talk of the current slowing is beginning to emerge again, what could happen in reality?

Concerns about the AMOC reaching a tipping point stem from the idea that significant changes or a slowdown in its circulation could have profound climate impacts, such as colder temperatures in Europe, changes in monsoons, and rising sea levels on the U.S. East Coast.

Recent scientific studies have provided valuable insights into the potential collapse of the current. A study published in Nature Communications by Peter Ditlevsen and Susanne Ditlevsen in 2023 warns of a possible collapse of the AMOC around mid-century. This study emphasizes the importance of the AMOC in the global climate system and suggests that a collapse could have significant climatic consequences​​. (i)

Another study, published in Nature Climate Change, discusses observation-based early-warning signals for a potential AMOC collapse. This research highlights the need to monitor the AMOC closely for any signs of weakening or destabilization, which could foreshadow significant changes in global climate patterns​​. (ii)

Furthermore, a study in Scientific Reports examined the decline and recovery of the AMOC in a warmer climate. This research provides insight into the complex interactions between the ocean’s heat and salt transport in the North Atlantic. The study demonstrates how these factors can contribute to both the weakening and potential recovery of the AMOC under increased atmospheric CO2 levels​​. (iii)

These studies collectively indicate a growing scientific concern over the stability of the AMOC and its critical role in regulating climate.

While there is some uncertainty about the exact timing and extent of a potential collapse, the research underscores the importance of continued monitoring and analysis of this vital oceanic system. The findings are a call to action for further research and potentially proactive measures to mitigate any significant climatic changes that a weakened or collapsed AMOC might bring.  There is current talk that the current could be reaching a tipping point, widely discussed in popular media – so what are the facts behind it?

The debate over the AMOC’s stability and the possibility of it reaching a tipping point is based on a mix of observational data, historical records, and climate models. Some recent studies have suggested that the AMOC is in its weakest state in over a millennium, likely due to climate change, particularly the melting of Greenland’s ice sheet which adds fresh water to the ocean, potentially disrupting the AMOC’s flow.

However, the notion of a tipping point – a threshold beyond which the AMOC would irreversibly collapse or significantly change – is still a topic of active scientific research and debate. While some models and theories suggest this is a possibility, others argue that the AMOC is more resilient than previously thought – so this is still up for debate.

However, even without a full collapse, any significant changes in the AMOC could have considerable climate impacts.

While there might be differing views on the likelihood of reaching a tipping point, and plenty of discussion around how serious a resultant ‘Big Freeze’ would be, the overall concern about the AMOC’s changes is based on substantial scientific evidence and should definitely not be dismissed as “fussing over nothing.”.

References

(i) https://www.sciencedaily.com/releases/2023/07/230725123122.htm

(ii) https://www.nature.com/articles/s41558-021-01097-4

(iii) https://www.nature.com/articles/s41598-023-43143-5