An idealized climate change simulation is used to investigate the energetics of the Atlantic meridional overturning circulation (AMOC) at the stages of its weakening and recovery. There is a good correlation between the strength of the AMOC and the available potential energy (APE) in the upper 3 km of the ocean, integrated north of 50°N or globally, both during the weakening and recovery. Buoyancy forcing is important at both stages. In the Southern Ocean, the APE gradually builds up and correlates with the depth of pycnocline in the Atlantic Ocean. This suggests that mechanical forcing plays an important role in the recovery of the AMOC.