Adapted from original article written by Johnathan Watts
Originally published by The Guardian (Fri, Feb 9, 2024)
Collapse in system of currents that helps regulate global climate would be at such speed that adaptation would be impossible
The circulation of the Atlantic Ocean is heading towards a tipping point that is “bad news for the climate system and humanity”, a study has found.
The scientists behind the research said they were shocked at the forecast speed of collapse once the point is reached, but said it was not yet possible to predict how soon that would happen.
Researchers developed an early warning indicator for the breakdown of the Atlantic meridional overturning circulation (Amoc), a system of ocean currents critical to climate regulation.
They found Amoc is already on track towards an abrupt shift, which has not happened for more than 10,000 years. It would have dire implications for large parts of the world.
Amoc is a marine conveyer belt that carries heat, carbon and nutrients from the tropics towards the Arctic Circle, where it cools and sinks into the deep ocean. This helps to distribute energy around the Earth and modulates the impact of human-caused global heating.
The Atlantic Meridional Overturning Circulation is weakening and has collapsed in the distant past
The system is being eroded by the faster-than-expected melt-off of Greenland’s glaciers and Arctic ice sheets. These pour freshwater into the sea and obstruct the sinking of saltier, warmer water from the south. Amoc is in its weakest state in more than a millennium, according to previous research.
The paper mapped some of the consequences of Amoc collapse. Sea levels in the Atlantic would rise by a metre in some regions, inundating many coastal cities. The wet and dry seasons in the Amazon would flip, potentially pushing the already weakened rainforest past its own tipping point. Temperatures around the world would fluctuate far more erratically. The southern hemisphere would become warmer. Europe would cool dramatically and have less rainfall. While this might sound appealing compared with the current heating trend, the changes would hit 10 times faster than now, making adaptation almost impossible.
“What surprised us was the rate at which tipping occurs,” said the paper’s lead author, René van Westen, of Utrecht University. “It will be devastating.”
He said there was not yet enough data to say whether this would occur in the next year or in the coming century, but when it happens, the changes are irreversible on human timescales.
