Scientists are warning that an important system of ocean currents in the Atlantic might be heading toward collapse.
The Atlantic Meridional Overturning Circulation acts "like a conveyor belt transporting heat and salt through the global ocean," said researcher René van Westen of Utrecht University in the Netherlands.
That process serves as a kind of "thermostat," Westen said, keeping temperatures mild in Western Europe.
Westen's recent study is part of a growing body of research showing that the AMOC may be approaching a tipping point.
The AMOC has been slowing down over the last century, and certain climate change factors may bring the current system past the point of no return.
Westen's research uses computer simulations to model the effects of freshwater inputs from melting Arctic ice sheets.
"AMOC is very sensitive to freshwater inputs," Westen said. "For example, the Greenland ice sheet is melting, it pours fresh water into the Atlantic Ocean, and that dilutes the ocean salinity."
In Westen's models, that interaction causes the AMOC to cross a "tipping point" and come to a full stop.
"That takes about 100 years," Westen said. "This may sound like a very long period, but for climate timescales, that is a very abrupt stop."
If the AMOC were to grind to a halt, sea levels could rise by multiple feet in some places, Europe could cool down, and rainfall patterns across Asia and Africa could shift dramatically.
Even Hawaiʻi could see some impacts, Westen said, though they would be relatively minor. Those effects could include slightly cooler temperatures and a sea level drop of a few centimeters.
"Maybe Hawaiʻi is not hit that severely compared to other regions, but people will definitely have severe consequences," Westen said. "It is very urgent that we take climate change way more seriously."
