Per-capita is relevant because as individuals, we find it easier to get a mental grasp on the lifestyles of other individuals than the actions of a nation state

Per-capita is relevant because as individuals, we find it easier to get a mental grasp on the lifestyles of other individuals than the actions of a nation state. Contrasting more/less efficient lifestyles is a way to understand our contribution to this problem. Do we need to put a leash on our corporations and governments so that they stop making policies that will kill our children? Absolutely, let's do that. Do we need to be more thoughtful about population growth? Certainly. But when it comes down to crafting policies that will be effective, it has to make sense on the both micro and macro scales. Holding per-capita measures as irrelevant hides the details that we're going to need to fix this.