The Atlantic Meridional Overturning Circulation, or AMOC, part of global ocean conveyor belt, brings surface warming and saline water northward in the Atlantic from low latitude to high latitude area, where the ocean loses heat to the atmosphere and the heavier salty water sinks, forming the North Atlantic Deep Water (NADW). Previous concept suggests that the weaken AMOC will reduce the heat transport to northern Atlantic, hence cooling Europe and even Northern Hemisphere. However, the latest research shows that this won’t happen in the presence of greenhouse-gas heating.
The new paper published in Nature on July 19 finds that dominant role of AMOC is changing from transporting surface heat northwards, warming Europe and North America, to storing heat in the deeper Atlantic ocean, buffering global surface warming. With multiple AMOC proxies, the paper shows that the weakened AMOC during 1975-1998 corresponds to a period of rapid surface warming, whereas, during recent global warming hiatus, the AMOC is accelerated.
This work is collaborated by Professor CHEN Xianyao from QNLM and Ocean University of China, andProfessor Ka-Kit Tung from University of Washington. The study was funded by the National Key Basic Research Program of China, Natural Science Foundation of China, and the U.S. National Science Foundation, and a Frederic and Julia Wan Endowed Professorship.
Figure. (a) The proxy of AMOC, (b) Global mean surface temperature