Atlantic Ocean circulation is reaching a critical ‘tipping point’ where it may never be reversed, scientists have said.
The circulation of the Atlantic Ocean is heading towards a ‘devastating’ tipping point that wouldn’t just be bad news for the climate, but also “humanity”, research has discovered.
Research into the early warning indicator for the breakdown of the Atlantic meridional overturning circulation (Amoc), looking at ocean currents that is vital to climate regulation has shown it’s heading towards a drastic shift. The abrupt change, that hasn’t been recorded for more than 10,000 years, would have devastating consequences for large parts of the world.
Scientists behind the study say they were shocked at the predicted speed of collapse if the tipping point is reached, but they say it’s not possible to forecast when it would happen.
Amoc is a marine conveyer belt carrying heat, nutrients and carbon from the tropics towards the Arctic Circle. Here, it cools and sinks into the deep ocean. It helps to distribute energy around the planet and helps to modulate global heating caused by humans.
However, Greenland’s glaciers, which are melting faster than expected, and ice sheets in the Arctic are eroding the currents. Amoc has declined 15% in the past 75 years (1950), and is now in its weakest state in more than a millennium.
Research of the Amoc declining has been undertaken previously, but there hadn’t been consensus on how severe the implications would be. A previous data-finding mission estimated the tipping point could occur between 2025 and 2095, but the Met Office in the UK said it was “very unlikely” in this century.
The new study has looked at warning signs in the salinity levels at the southern extent of the Atlantic Ocean, between Cape Town and Buenos Aires, simulating changes on computer models for the next 2,000 years. It found a slow decline may lead to a sudden collapse over 100 years with dangerous consequences.
The paper, published in Science Advances, said it was “bad news for the climate system and humanity as up till now one could think that Amoc tipping was only a theoretical concept and tipping would disappear as soon as the full climate system… was considered.”
Using the computer models, it mapped what could occur if it happened in the 21st century, including sea levels rising by a meter in some regions, having drastic implications for cities on the coasts. It would flip the wet and dry seasons in the Amazon, which could be catastrophic for the vulnerable rainforest.
It also listed temperatures around the world fluctuating erratically as another consequence, as well as the southern hemisphere becoming hotter. Europe, on the other hand, would have less rainfall and would cool drastically. This changes would happen 10 time faster than now, so adapting to the ever-changing climate wouldn’t be possible.
Rene Van Westen of Utrecht University, the paper’s lead author, said it “will be devastating”, and the changes are irreversible on human timescales.
Although he said there wasn’t enough data on when it would happen, whether within the next 12 months or the next 100 years.
He called it “kind of scary”.
