Because he’s lying to us. He stands to profit handsomely if C02 is taxed, not exactly an uninterested party.
“The common enemy of humanity is man. In searching for a new enemy to unite us, we came up with the idea that pollution, the threat of global warming, water shortages, famine and the like would fit the bill. All these dangers are caused by human intervention, and it is only through changed attitudes and behavior that they can be overcome. The real enemy then, is humanity itself.”
– Club of Rome