UK on brink of disastrous weather collapse – our food security would be finished

The collapse of a vast system of ocean currents which help push heat towards the UK would potentially lead to colder winters, hotter summers, floods and droughts, experts suggest. The Atlantic Meridional Overturning Circulation (AMOC) carries warm water from the tropics northwards across the Atlantic, helping to keep Europe warm, and in turn the system sends cooler water southwards.

Scientists warn the AMOC could weaken to the point where it no longer warms the UK and Europe as a result of seas getting heating up, ice melting and rainfall rising. Jon Robson, Professor of Climate Science at the University of Reading, said the extent of any future weakening is uncertain and it would not happen overnight. He said: "An IPCC (Intergovernmental Panel on Climate Change) report suggests there is high confidence it will decline, but low confidence about how much and how fast."

Professor Robson added: "It's a risk for us, especially if it goes into irreversible decline. But it would be a real worry for people who rely on monsoons too.

"There would be increased migration out of monsoon areas if the worst case scenario unfolds. But it's a big 'if'. It's not likely at this stage.

"Others, however, argue it is more likely than previously thought. We can't rule out these kinds of worst case scenarios. It won't happen overnight... We're confident it is going to decline, but not by how much."

Jon Baker, Senior Climate Scientist at the Met Office, said modelling shows there is much uncertainty as to whether the AMOC will collapse this century, but after 2100 models show the risk increasing.

He said: "The impacts depend on how much it weakens by. Some impacts include changes in global rainfall patterns and changes in the jet stream, bringing stronger winter storms.

"It all depends on how much the AMOC weakens by, and that remains uncertain. A collapse remains unlikely this century. In a collapse, if it occurs, we would expect regional cooling and that would take a long time."

Professor Robson said scientists are "very confident" more global warming will lead the AMOC to decline. He said balancing the amount of greenhouse gases we emit and remove from the atmosphere is our "most feasible" strategy to prevent the system from weakening.

The expert warned: "If we continue to emit more, then the risk of a long term, irreversible decline only increases."

While there is uncertainty about the potential impacts of a weakened or collapsed AMOC, scientists warn a worst case scenario would see farmers reliant on rain-fed agriculture hit hard.

The UK's food security would also be at risk as we would be much more reliant on imports. Food prices could also rise as demand outstrips supply.

Professor Robert Marsh from the National Oceanography Centre at the University of Southampton said a weaker AMOC will reduce the maritime influence on Britain's climate, potentially leading to colder winters, hotter summers and more erratic rainfall.

He said: "With foresight and adaptation, an optimistic view is that food prices can be managed through a long-term weakening era.

"The greater risk is a more abrupt AMOC weakening that would change our weather and climate faster than we can adapt across the region – then prices would more likely have to rise."

The expert, who has been involved in researching the system for 25 years, said he was confident the AMOC has weakened by 5-10% between 2004 and 2024.

He added: "I am further confident that ongoing projected changes in the wider climate system mean that this trend will continue for the next 20 years – extrapolated to a 10-20% weakening over 2004-44."

Scientists believe the AMOC has been largely stable since the end of the last Ice Age. Monitoring of the system has been carried out regularly since 2004, after occasional surveys since the 1950s.

Professor Marsh said that the first five seasons since 2004 saw the AMOC behave as expected, but between 2009 and 2011 it dipped and stalled for about a month.

He explained that this reduced warming in the mid-Atlantic, coinciding with two unusually snowy winters. The AMOC then recovered, but in a weaker state, according to Professor Marsh.

Professor Marsh said the risk of a more abrupt weakening remains low over the coming decades, but cannot be ruled out.

He suggested the AMOC's stabilisation at a reduced strength by the middle of the century may be a medium-term outcome of efforts to cut greenhouse gas emissions.

The expert said this would be a "bonus reward" for stabilising our climate globally.