What is the Atlantic Meridional Overturning Circulation (AMOC)?

GS Paper 1 Topics Covered: Important Geophysical phenomena   Context: According to a recent study, the Atlantic Ocean’s current system-AMOC, an engine of the Northern Hemisphere’s climate, could be weakening to such an extent that it could soon bring big changes to the world’s weather. Climate models have shown that the AMOC is at its weakest …