Gulf Stream collapse would throw tropical monsoons into chaos for at least 100 years, study finds

Atlantic Ocean currents that carry heat to the Northern Hemisphere could be grinding to a halt due to climate change. And if the vital currents do slump, tropical monsoon systems would be thrown into chaos for at least a century, a new study suggests.

The Atlantic Meridional Overturning Circulation (AMOC) is a huge conveyor belt of ocean currents, including the Gulf Stream, that pumps heat and salt from the South Atlantic to the North Atlantic. "I like to think of it as a sort of ventilator," study lead author Maya Ben-Yami, a climate researcher specializing in climatic tipping points at the Technical University of Munich in Germany, told Live Science. "Part of the reason that we're worried about the collapse of the AMOC is because it has such a huge impact on the sort of heat transport within the Earth system."

Global warming threatens the AMOC because it is melting glaciers and ice sheets, which then ooze fresh water into the North Atlantic. This dilutes the salinity of the top layers of water and prevents them from sinking to the bottom of the ocean, where they would normally drive the circulation back south.

"The AMOC basically depends on saltier, denser water sinking down in the North," Ben-Yami said. "By freshening that water, you're basically stopping the circulation."

An AMOC collapse is likely to trigger climatic changes around the globe, but the Northern Hemisphere and tropical monsoon regions are on the frontline, Ben-Yami said. Researchers have long suspected that a weakening of the AMOC would disrupt tropical monsoon systems, but the new study gives a far more detailed picture of what's likely to come, she said.

Related: The Gulf Stream stopped pumping nutrients during the last ice age — and the same could be happening now

Tropical monsoons occur in a narrow band of low-pressure atmospheric conditions that wraps around Earth near the equator. Trade winds from the Northern and Southern hemispheres flow into this band, which is known as the Inter-Tropical Convergence Zone (ITCZ), leading to heavy rainfall and thunderstorms during several months of the year.