Impacts of a weakening AMOC

It has been shown that periods of strong Atlantic meridional overturning circulation (AMOC) coincide with a cooling of the deep ocean and a warming of the surface waters.

From NOAA: The Atlantic Meridional Overturning Circulation (AMOC) is an important component of the Earth’s climate system, characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder water in the deep Atlantic. This ocean circulation system transports a substantial amount of heat from the Tropics and Southern Hemisphere toward the North Atlantic, where the heat is transferred to the atmosphere. Changes in this circulation have a profound impact on the global climate system, as indicated by paleoclimate records.

It has recently been proposed that due to global warming, the relationship between the AMOC and ocean temperatures may have reversed. This means that during past decades a strong AMOC supposedly coincided with a warming of the deep ocean and a relative cooling of the surface waters by transporting increasingly warmer waters downward.

This peer-reviewed study, which was recently published in the Environmental Research Letters, provides evidence that leads to the opposite conclusion of the above proposal. The authors show that during the ongoing global temperature rise, a strong AMOC warms the surface waters as climate models have predicted. Based on this new evidence the authors conclude that the current observed weakening of the AMOC has actually delayed global surface warming, instead of enhancing it.

Here is a link to the actual study.