If the first world population used air conditioning less, it would allow poor people, the third world, who tend to live in environments that are hotter and more subject to costs of climate change, to use air conditioning more without adding more to humanity's carbon footprint.
We as humans are quite greedy. We can live perfectly happy and comfortable lives with less plastic, less driving, less waste, but we have become addicted to all this consumption, all this convenience, and the ever greater convenience of consumption (couch shopping and to-your-door delivery, same day or hour even). We have tied our happiness to it. We have no qualms about being a small fraction of the Earth's population yet consuming and hoarding an extremely disproportionate amount of its resources, usually at the expense of poorer people, apparently because a meritocracy is at work.
The modern world's values are ever more driven by "me, me, me!" and less by "us".