The global warming hypothesis is really complicated. But, even though it is complicated, it represents a simplification the IPCC made of the actual atmospheric physical processes. The simplifications made by the IPCC suited their purpose, which was to show that CO2 was driving the earth to higher temperatures. Their mission was never to understand the processes involved in the atmosphere. Here is a paper that discusses what the IPCC didn’t consider. (This paper does require some knowledge of mathematics and physics.)