Scientists reported in a new study that human-caused climate change has disturbed a broad system of ocean currents in the Atlantic, including the Gulf Stream.
If that thing collapses, global weather patterns will be drastically altered.
The Atlantic Meridional Overturning Circulation (AMOC) system is critical to the functioning of the world's oceans, moving warm, denser saltwater from the tropics to northern Europe, where it cools and returns along the ocean floor.
However, according to a new study published in the journal Nature Climate Change by the Potsdam Institute for Climate Impact Research in Germany, this system is growing increasingly vulnerable to perturbations.
The findings back previous research that revealed the AMOC system to be at its weakest in 1,600 years.
According to the Washington Post, if this circulation fails, it could bring extreme cold to Europe and parts of North America, raise sea levels along the U.S. East Coast, and disrupt seasonal monsoons that provide water to much of the planet.
It would also put the Amazon jungle and Antarctic ice sheets in jeopardy, The Guardian said.
This isn't the first time AMOC has been linked to a crisis. Another study published in February predicted that as Arctic ice and the Greenland Ice Sheet continue to melt, AMOC might be decreased by 34% to 45% by the end of the century.
The new report, however, adds to the increasing scientific concern over AMOC's integrity.
The AMOC was last switched around 12,000 years ago, towards the conclusion of the last ice age, due to the melting of a huge glacial lake. Europe was hit by an intense cold spell that lasted nearly a millennium.
Scientists have long believed that AMOC has decreased as sea temperatures rise due to human activities and greenhouse gas emissions. What is unknown is when greenhouse gases will pile up to the point where the AMOC will shut down.
A 2016 study said the AMOC could collapse by 2300 if no serious efforts to reduce greenhouse gases are made before then.
For the time being, it is hard to predict the date of any collapse due to the intricacy of the AMOC system and uncertainties about future degrees of global warming. It could happen in the next decade or two, or it could take millennia.
However, because of the significant implications, scientists believe it should never be permitted to happen.