The collapse of the current system that helps regulate the global climate would be so rapid that adaptation would be impossible, writes The Guardian.
The Atlantic Current System Regulates Global Climate Photo Shutterstock
The circulation of the Atlantic Ocean is heading towards an inflection point that represents “bad news for the climate system and for humanity,” according to a study.
The scientists who carried out the research said they were shocked by the predicted speed of collapse once the tipping point is reached, although they said it was not yet possible to predict how quickly this would happen.
Using computer models and historical data, researchers have developed an early warning indicator for the collapse of the Interoceanic Circulation System (Amoc), a vast system of ocean currents that is a key component in regulating the global climate.
The researchers found that Amoc is already on the verge of a sudden change that hasn't happened in over 10,000 years and would have serious implications for large parts of the world.
The Amoc, which includes part of the Gulf Stream and other strong currents, is a marine conveyor belt that transports heat, carbon and nutrients from the tropics to the Arctic Circle, where it cools and sinks into the deep ocean. This turbulence helps distribute energy around the Earth and modulates the impact of human-induced global warming.
But the system is being eroded by the faster-than-expected melting of Greenland and Arctic glaciers, which is pouring fresh water into the sea and preventing saltier, warmer water from the south from sinking.
Amoc has fallen 15 percent since 1950 and is in its weakest state in a millennium, according to previous research that led to speculation of an imminent collapse.
So far there has been no consensus on how serious this will be. A study last year based on changes in sea surface temperatures suggested the tipping point could occur between 2025 and 2095. However, the UK's Met Office said the large and rapid changes in Amoc are “very unlikely” in the 21st century.
The new work, published in the journal Science Advances, broke new ground by looking for warning signs in salinity levels at the southern boundary of the Atlantic Ocean between Cape Town and Buenos Aires. By simulating changes over a period of 2,000 years on computer models of the global climate, it found that a slow decline can lead to a sudden collapse in less than 100 years, with disastrous consequences.
According to the paper, the results provided a “clear answer” regarding the possibility of such a sudden change: “This is bad news for the climate system and for humanity, because until now it was believed that Amoc tipping was only a theoretical concept and that the tipping would disappear as soon as the entire climate system with all its additional reactions was considered.” .
It also mapped some of the aftermath of the Amoc crash. Sea levels in the Atlantic would rise by one meter in some regions, flooding many coastal cities. The Amazon's wet and dry seasons would reverse, potentially pushing the already weakened rainforest beyond its own tipping point. Temperatures around the world would fluctuate much more erratically. The southern hemisphere would become warmer. Europe would cool drastically and have less precipitation. While this might seem appealing compared to the current warming trend, the changes would hit 10 times faster than today, making adaptation nearly impossible.
“What surprised us was the speed with which the tipping occurs,” said the paper's lead author, René van Westen, from Utrecht University. “It will be devastating.”
He said there is not yet enough data to say whether this will happen in the next year or the next century, but when it does, the changes are irreversible on the human time scale.
Meanwhile, the direction of travel is undoubtedly in an alarming direction.
“We're heading for it. That's pretty scary”, van Westen said. “We need to take climate change much more seriously.”