One of the most important climate systems in the world could already be on the brink — pushing it beyond is no longer a ‘low likelihood’ event.
The Amoc — or Atlantic meridional overturning circulation — brings warm tropical water to northern European coastline and the Arctic, which then cools and sinks to form a return current deep in the ocean. In recent years, a number of analyses have pointed to the climate change vulnerability of this vital pattern, which is now at its weakest in some 1,60o years.
If this collapses, as it has in the past, it would lead to a seismic change in weather systems across vast swathes of both the tropics and the Western Northern Hemisphere. Europe would face far harsher winters and drought-riddled summers, while the planet’s central precipitation belt would essentially move, wreaking havoc on areas which are home to farmland and precious natural ecosystems such as rainforests.
According to a new analysis, while it was previously thought Amoc was unlikely to be seriously affected by global warming before the end of this century, very little has been done to look at more distant days. First published int he journal Environmental Research Letters, the assessment looked at standard models used by the Intergovernmental Panel on Climate Change [IPCC] used to determine the potential fate of this system. Based on this, with projections using to 2300 and 2500, even intermediate and low-emission scenarios showed a slow down towards 2100, then a complete shut down after this.
Even more worrying, the so-called ‘tipping point’ — after which there is no ability to stop this process happening due to self-perpetuation — could already be on the horizon. Should carbon emissions continue to increase at the current rate, there’s a 70% chance of Amoc’s collapse, 37% for intermediate emissions, and 25% for low emission modelling. In any case, this would come between 50 and 100 years after the ‘point of no return’, suggesting this is now within a matter of decades. The conclusion has also been supported in a second study published by the Department of Physics, Institute for Marine and Atmospheric Research at Utrecht University.
Image: Rod Long / Unsplash
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