The Atlantic Meridional Overturning Circulation (AMOC) is responsible for circulating water in the Atlantic Ocean globally and exerts a large influence on the climate and weather patterns. Experts worry that it might be weakening and could even collapse, as more and more freshwater enters the surface of the Labrador Sea due to ice melt.

Nicolas Grisouard, a professor at the University of Toronto, Department of Physics, explains how AMOC works and its impact in an interview with CBC. The process initiates at high latitudes, where denser water forms due to cooler temperatures and brine rejection due to ice formation. Over the course of centuries, colder water sinks at the poles and the warmer tropical water rises, creating a circulation.

A new study shows that the AMOC could stop entirely by the end of the century.  According to insights from Professor Grisouard, “if we melt a lot of ice, especially from Greenland, we will release a lot of freshwater into the upper ocean of the North Atlantic. This could collapse or could just stop the circulation.”

The ocean current depends upon a delicate balance of salt and freshwater.  As more fresh water is added into the oceans, it slows the cold, salty water from sinking as it is lighter. When that water doesn't sink, the AMOC conveyor belt slows down and could potentially stop altogether.

So, what could this look like?

Prof. Grisouard explains that it is highly speculative, but people believe Northern Europe will cool down a little bit, and that it might disrupt the rains. So, we might see crop failures, the oxygen in the water might decrease, which might in turn cause great harm to ecosystems. Beyond its impact on oceanic life, the AMOC exerts a significant influence on temperature regulation across continents, contributing to the severity of weather events.

More information here: What happens if a crucial ocean current collapses? | About That - YouTube