I'm curious if you feel the meterological science that was done 40+ year ago before there were really computers more powerful than a Commodore 64 compares to the staggering advances in understanding and the use of supercomputers now? Science always makes the best estimation of the data at the time - and then the press completely gets it wrong (which is what they did went wild with non-peer reviewed nonsense paid for by the oil industry way back then). But hey, we can take comfort in the fact that we now KNOW that we're in extremely deep do-do due to human-produced climate change, and that 98.83% of all the global peer-reviewed scientific literature on the subject since 1990 is in agreement. It's good to be skeptical... but it's better to be informed.
Fat that goes to the landfill ferments anaerobically and becomes methane, which is thirty times more powerful of a greenhouse gas than carbon dioxide (the product you get when soap is eventually broken down by bacteria under aerobic conditions. Therefore soaping animal fats is also very green (in addition to the positives that you mention).