In April 1990, Al Gore published an open letter in the New York Times "To Skeptics on Global Warming" in which he compared them to medieval flat-Earthers. He soon became vice president and his conviction that climate change was dominated by man-made emissions went mainstream. Western governments embarked on a new era of anti-emission regulation and poured billions into research that might justify it. As far as the average Western politician was concerned, the debate was over.

But...