Atlantic ocean currents that respond to climate change are hurtling toward a tipping point that could cause severe impacts before the end of this century, a new study finds.

The currents are those that form the Atlantic Meridional Overturning Circulation (AMOC), which loops around the Atlantic Ocean like a giant conveyor belt, bringing heat to the Northern Hemisphere before traveling south again along the seabed. Depending on how much carbon humans emit in the next few decades, the AMOC could reach a tipping point and start to collapse as early as 2055, with dramatic consequences for several regions, researchers found.

This scary prediction, based on a scenario where carbon emissions double between now and 2050, is considered unlikely — but the outcome of a much more likely scenario where emissions hover around current levels for the next 25 years isn't much better, according to the study. Even if we keep global warming this century to 4.8 degrees Fahrenheit (2.7 degrees Celsius) above preindustrial levels — a "middle of the road" scenario, according to the latest U.N. climate report — the AMOC will start to collapse in 2063, the results suggest.