The Atlantic Meridional Overturning Circulation is a vast climate conveyor belt of ocean currents which warms the North Atlantic, and thus the UK and Europe, by bringing warm water up from the tropics.
This warm surface water gradually evaporates as it travels north, getting saltier and heavier in northern seas, creating a deep double-back of cold water which flows as far south as the Antarctic. There it mixes and returns to the surface in a complicated process called ‘upwelling’, then heads north and warms up once more, to go round again.
This world-scale system helps regulate many aspects of the global climate, as well as moving nutrients around which are relied upon by delicate marine eco-systems. Of particular interest to the UK, it helps prevent severe winters and explains why England can actually grow grapes at the around the same latitude that polar bears live in Canada.
Climate scientists have measured a portentous slow down (of around 15%) in the past few decades, due to rising levels of cold fresh water blocking the process as increasing levels of Greenland ice melt into the ocean as a result of our heating climate. The very real concern is that it is approaching a tipping point that within mere decades will cause a collapse, resulting in a severe cooling across the UK and northern Europe, as well as huge changes in global climate and ocean eco-systems. We would find it hard to grow food in the UK, while import prices would also soar because of bread-basket collapses elsewhere.
An open letter to the Nordic Council of Ministers was signed last year by more than 40 international climate experts warning that a string of new studies show the threat of AMOC collapse had been severely underestimated, and was increasingly unavoidable as the world warms to 1.5-2˚ above pre-industrial average temperatures. They call for urgent action and warn that meaningful adaptation may not be enough in the face of extensive food shortages.
They urge the Nordic Council to leverage their power as a block with other European countries to pressure for more urgent action on emissions cuts in the hope of staying nearer to the 1.5˚ limit envisaged by the Paris Agreement.
In the UK, the National Preparedness Commission has produced its own report urging ministers to take urgent action and to push hard on the world stage for the huge changes necessary, as the 30th ‘Conference Of Parties’ (#COP30) meets in Brazil. No UK minister is attending COP30, sending instead a Climate Envoy, Rachel Kyte, and a Nature Envoy, Ruth Davis on behalf of the Foreign Secretary and the Dept of Environment. Prince William has also flown ti Brazil in his private jet to promote his #Earthshot prize.
Activists have formed the AMOC Bomb Project to try and bring the issue to the attention of government and public, in the face of inaction and media disinterest.
