Greenland Meltwater Weakens Atlantic Current

A state-of-the-art climate model projects that Greenland meltwater will weaken the Atlantic Meridional Overturning Circulation steadily under continued global warming, but the change would not mark an irreversible tipping point. The circulation carries warm tropical water northward, where it cools, sinks, and returns south along the ocean floor.

Fresh meltwater from Greenland reduces the density of this water and slows its descent.

Atmospheric warming alone would reduce the circulation's strength by 60 percent by 2300. Adding increasing Greenland meltwater would cut another 20 percent from its strength. If carbon dioxide concentrations fall by 1 percent per year beginning in 2250, the model shows the circulation recovering fully by about 2400.

A prior model found that constant-rate meltwater additions could push the circulation past a tipping point. The new simulation incorporates rising melt rates that match observed trends. Researchers note that results remain model-dependent and that other factors, such as Antarctic meltwater, could also affect the circulation.

An 80 percent weakening could still disrupt European agriculture and tropical monsoon patterns, though the decline would occur gradually and respond to cumulative emissions reductions.