This is a little off topic, but I thought of another objection. Does anybody ever claim that humans were responsible for the increase in CO2 in the atmosphere? It’s always “humans emit a lot of CO2” and “CO2 concentrations in the atmosphere have increased by 100 ppm”. But do they ever claim that there is a causal relationship? I think that CO2 concentrations have gone up for natural reasons due to more warming from the sun, not because humans blew it there with factories. As such not even the increase in CO2 concentrations is manmade.