Research, which is still on going, suggests that the topping point which will make the collapse of AMOC inevitable could be passed in the next few decades – but the resulting collapse of the system might take another 50-100 years to happen. Even keeping the global temperature rise to the 1.5C Paris target is now predicted to carry a 10-25% risk of reaching this tipping point before the end of the century. It is a risk we cannot afford to take given the impact it will have on the viability of human life – even if that will not effect us now, it will effect future generations, our children and our children’s children. (2)
The oceans redistribute cold and warm water across the globe influencing winds – both direction and intensity – and weather patterns. Ocean currents enable the flow of water from hotter to cooler areas (tropics to the poles) and by the flow of water between areas of higher to lower salt density. Here in the UK we particularly benefit from the warmth that the Atlantic currents bring giving us mild winters and year round rainfall.
The driving force for these ocean currents lies in the artic regions. The density of the cold, saline rich waters causes the waters here to sink and as they do this pulls in warmer waters from the tropics. However as sea ice and icecaps melt, so the water becomes less salty, and less inclined to sink, reducing the energy that pulls the oceanic currents. In the North Atlantic this driving force is known as the Atlantic Meridional Overturning Circulation or AMOC.
Here in the UK, our climate and weather patterns are highly dependent on the functioning of AMOC. If this slows or becomes unstable, it will impact temperature and rainfall patterns cross Europe and giving us in the UK and Northern Europe a much colder, wetter climate. And at the same time changing the climate in southern Europe, making it hotter and dryer.
Whilst there are signs that AMOC is weakening, it is hard for predict quite how quickly and to what degree it will change as global temperatures rise. On the other hand the potential damage a change in AMOC will cause, should make decision-makers focus on avoiding that as a matter of urgency.
“The risk of a critical AMOC transition is real and very serious, even if we cannot confidently predict when and whether this will happen. We have already left behind the stable Holocene climate in which humanity has thrived (Osman et al., 2021), and the latest IPCC report warns us that beyond 1.5°C of global warming, we move into the realm of “high risk” with respect to climate tipping points (IPCC, 2023).” (1)
The Green Tau 