If I accepted "Global Warming", my first thought would be Buffet is daft. So, he has no agricultural products, no products dependent on agricultural products, no transportation related businesses that could be impacted by global warming restictions and energy availability, no products or transportation enterprises that give off hydrocarbon by-products....etc, and so on and so on.....
No impact from "global warming", indeed.
With that said, he's right because there is no impact from global warming, but then, I don't believe the "global warming" myth.