And the consequences of this slowing process, which could occur within a few years, could be severe.
According to the research, published in the journal Nature Climate Change, the stopping of this current could lead to large-scale climate change throughout the world.
The Atlantic Meridional Overturning Circulation, or AMOC, exists because of varying temperatures and salt content in the world’s oceans – it transports warm water masses from the tropics northward at the ocean surface and cold water with less salt content southward at the ocean bottom. It is largely the Gulf stream which is responsible for Europe’s mild winter climate.
And now the system is at its weakest in the past 1,600 years and could well be close to a complete stoppage.
“A detailed analysis of these fingerprints in eight independent indices now suggests that the AMOC weakening during the last century is indeed likely to be associated with a loss of stability,” said Boers, the author of the study.
“This shows that the ‘global “conveyor belt’ has already begun losing its stability and is close to collapse. The signs of destabilisation being visible already is something that I wouldn’t have expected and that I find scary.”
Scientists have long warned of a slowing in the AMOC current, but are so far unable to say how long ago the process began.
Boers believes the currents has been slowing since at least 1880. And it has now become increasingly unstable.
“I wouldn’t have expected that the excessive amounts of freshwater added in the course of the last century would already produce such a response in the overturning circulation,” says Boers.
The melting ice cap in Greenland also affects the slowing process of the currents – adding large amounts of fresh water to the world’s oceans.
The slowing of the currents could bring down temperatures in Europe, raise sea levels in North America and produce catastrophic changes to levels of rain in India, South America and Africa.