The Atlantic Meridional overturning circulation (AMOC)—a key conveyor belt for ocean water and air, creating the weather—is slowing down, according to a study published in the journal Nature. Seth Borenstein reports for AP on the slowdown in circulation, a crucial part of Earth’s climate. Warm water moves north from the tropics, off the U.S. East Coast and to the North Atlantic, where it cools then heads south.
“This overturning circulation redistributes heat on our planet,” said lead author Levke Caesar, a physicist at the Potsdam Institute. The slowdown could potentially culminate in a complete circulation shutdown. “We know somewhere out there is a tipping point where this current system is likely to break down,” said study co-author Stefan Rahmstorf, a climate scientist at the Potsdam Institute. However, the authors of the study aren’t sure when this collapse could occur. “This is uncharted territory,” said Rahmstorf.
The study found that since the middle of the 20th century, the speed at which the ocean moves water in the AMOC has dropped 15 percent. Scientists blame global warming, noting that warmer water lessens the amount of cooling and makes it harder for the water to sink and turn over. There is also more rain and snow in northern areas and more evaporation in southern areas, which alters the flow of the AMOC. Despite this study, other scientists in the field doubt its conclusion. Although conceivable, MIT’s Carl Wunsch believes that the study is “unsupported by any data.” Still, Caesar believes that we should expect changes. “It’s a slow change at the moment, but we’re changing it,” he said.