Atlantic at risk of circulation collapse within next few decades

Amid news of lethal heatwaves across the Northern Hemisphere comes the daunting prospect of a climate disaster on an altogether grander scale. New findings published in Nature Communications suggest the Atlantic meridional overturning circulation, or Amoc, could collapse within the next few decades – maybe even within the next few years – driving European weather to even greater extremes. The Amoc amounts to a system of currents in the Atlantic that bring warm water northwards where it then cools and sinks. It is a key reason why Europe’s climate has been stable for thousands of years, even if it’s hard to recognise this chaotic summer as part of that stability.
There is much uncertainty in these latest predictions and some scientists are less convinced a collapse is imminent. Amoc is also only one part of the wider Gulf Stream system, much of which is driven by winds that will continue to blow even if the Amoc collapses. So part of the Gulf Stream will survive an Amoc collapse. But I have studied the links between Atlantic currents and the climate for decades now, and know that an Amoc collapse would still lead to even greater climate chaos across Europe and beyond. At minimum, it is a risk worth being aware of.
To appreciate how much Amoc influences the climate in the northeast Atlantic, consider how much warmer north Europeans feel compared to people at similar latitudes elsewhere. Most striking in the northern winter (January) is a red spot centred to the west of Norway where temperatures are 20°C warmer than the latitude average, thanks to Amoc. The northeast Pacific – and therefore western Canada and Alaska – enjoys a more modest 10°C warming from a similar current, while prevailing westerly winds mean the northwest Atlantic and northwest Pacific are much colder, as are the adjacent land masses of eastern Canada and Siberia.
Highly variable day to day weather
The weather and climate of Europe, and northern Europe in particular, is highly variable from day to day, week to week and year to year, with competing air masses (warm and moist, cold and dry, and so on) gaining or losing influence, often guided by the high-altitude jet stream. Changes in weather and climate can be triggered by events located far away – and over the ocean. Over recent years Europe has witnessed some particularly unusual weather, in both winter and summer. At the same time, peculiar patterns of sea surface temperatures have appeared across the North Atlantic. Across great swathes of the ocean from the tropics to the Arctic, temperatures have persisted 1°C-2°C above or below normal levels, for months or even years on end.