I indelicately started a contentious topic that didn't have to exist. If I were given a fresh chance, I'd have just said that carbon emissions and the changes they are causing to the planet are a bigger problem than any single economic class or nation.
That might have caused some controversy, too, but is closer to what I meant. Your point is well taken, but maybe if I posted differently the ensuing discussion would have been less acrimonious.
I think you spoke directly to the room's elephant. The topic is contentious because it is less than zero sum. It isn't even that the pie cannot be grown larger, but some people have already eaten most of it and must continue to eat as more people decide they also want pie.
Human activity will have climatic impact. At a specific emission rate per capita, what is the number of humans that can exist? Who decides which humans continue to exist?