Atlantic Meridional Overturning Circulation stability linked to warming speed

Researchers at Utrecht University have published a study in 'Nature Climate Change' suggesting that the stability of the Atlantic Meridional Overturning Circulation (AMOC) depends more on the speed of global warming than on specific temperature thresholds.

According to the climate models, if CO2 concentrations increase slowly at a rate of 0.5 ppm per year, the current remains stable even with 5.5 degrees Celsius of global warming. However, if the increase is faster—at 2.5 or 5.0 ppm per year—the circulation could collapse at approximately 2.0 degrees Celsius of warming.

This finding challenges previous estimates that placed the collapse threshold at roughly 4.0 degrees Celsius. The research indicates that the rate of warming determines whether surface water and deep ocean layers can adapt or if the system will undergo a tipping point.