Change in global ocean heat content between the surface and 2000 meters of depth from 1958 to 2017 (top) and distribution of ocean heat content anomalies in 2017 (bottom). (carbonbrief.org)
If this was so widely supported by the community, there would be an actual paper that used this equation to calculate atmospheric heat content anomalies surely? (realclimate.org)
There is nowhere in that paper, or any other, that relies on some assumption about atmospheric heat content anomalies. (realclimate.org)