Climate change could become so extreme that it might trigger the cataclysmic collapse of a vital Atlantic Ocean current and plunge parts of the Northern Hemisphere into a frigid new reality, a study warns.
The Atlantic Meridional Overturning Circulation (AMOC) transports warm water from the tropics to the North Atlantic and helps regulate climate and weather patterns all over the world. As it releases the warmth into the air, the cooling water sinks and flows back to the tropics to repeat the process. But researchers fear that as the air in the north warms significantly due to climate change, the AMOC won’t be able to transfer its warmth to the atmosphere and the great circulatory engine of the ocean could stagnate and shut down.
“It is a major player in the climate system, important for Europe and North America. So it’s a big deal,” Tom Delworth, a scientist at the National Oceanic and Atmospheric Administration, told The Verge.
The doomsday scenario is chillingly like the plot of the sci-fi movie “The Day After Tomorrow,” in which the collapse of an ocean current turns North America and Europe into frigid wastelands in a matter of weeks.
The risk was uncovered by Yale University scientist Wei Liu, who has calculated in a study published in Science Advances that the AMOC could collapse within 300 years once atmospheric carbon dioxide increases to 710 parts per million. Last week’s levels were 405 parts per million. There is already evidence that the AMOC has slowed, according to the paper. A shutdown would trigger “prominent cooling” of the northern North Atlantic and a “remarkable sea ice expansion,” according to Wei’s model. In addition, the normal rain belt of the temperate areas would be pushed significantly southward over the tropical Atlantic.
The model also predicts disruptions in other parts of the world. Without cold water moving south again, the new scenario indicates a stronger warming pattern south of the equator, creating far more rain for places like northeastern Brazil and less rain for Central America. The model also predicts a greater reduction in Antarctic sea ice.
Wei warns that this fragility in the life-sustaining AMOC has been overlooked in climate change models. “The significance of our study is to point out a systematic bias in current climate models that hinders a correct climate projection,” he said in a statement.
The concern about AMOC “is a very provocative idea,” said study co-author Zhengyu Liu of the University of Wisconsin-Madison. “For me, it’s a 180-degree turn because I had been thinking like everyone else,” he added, referring to his earlier perspective that the AMOC would remain relatively stable regardless of the effects of climate change.