To learn more about the Earth energy imbalance, check out this paper:
Heat stored in the Earth system: where does the energy go?
The Earth's climate is getting warmer. Yes, but how much? And where is all this energy being redistributed and stored? This study is a concerted international effort to update the Earth heat inventory, assessment of ocean warming and heat gain in the atmosphere, cryosphere and land over the period 1960–2018. They are all key parameters to calculate the Earth energy imbalance (EEI), the most critical number defining the prospects for continued global warming.