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How could melting Greenland glaciers weaken the Atlantic Meridional Overturning Circulation?

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Map of the North Atlantic Ocean showing major ocean currents, with warm currents like the Gulf Stream and North Atlantic Drift highlighted in pink and cold currents in blue. Arrows indicate current directions and relative speeds, connecting the eastern coasts of North America, the western coasts of Europe and Africa, and the Arctic region. — Gulf Stream Major warm and cold currents of the North Atlantic Ocean.

The Atlantic Meridional Overturning Circulation (AMOC) relies on a process where warm surface water flows northward, cools, and becomes dense enough to sink into the deep ocean, effectively driving the circulation system.12

Melting Greenland glaciers weaken this mechanism by introducing large volumes of fresh water into the North Atlantic. Because fresh water is less dense than saline water, this influx reduces the overall salinity and density of the surface water. As a result, the water becomes too buoyant to sink efficiently, which inhibits the downward flow that powers the AMOC.312

This weakening of the circulation—of which the Gulf Stream is a key surface component—can disrupt the transport of heat toward northern regions, potentially leading to significant climatic shifts. While some models predict a gradual decline, others suggest that continued global warming could lead to more severe disruptions, similar to historical events where massive freshwater releases caused the circulation to collapse.1425