He doesn’t deny global warming. He likes global warming. From Nicholas Dawidoff’s profile in the New York Times Magazine:
Dyson agrees with the prevailing view that there are rapidly rising carbon-dioxide levels in the atmosphere caused by human activity. To the planet, he suggests, the rising carbon may well be a MacGuffin, a striking yet ultimately benign occurrence in what Dyson says is still “a relatively cool period in the earth’s history.” The warming, he says, is not global but local, “making cold places warmer rather than making hot places hotter.” Far from expecting any drastic harmful consequences from these increased temperatures, he says the carbon may well be salubrious — a sign that “the climate is actually improving rather than getting worse,” because carbon acts as an ideal fertilizer promoting forest growth and crop yields. “Most of the evolution of life occurred on a planet substantially warmer than it is now,” he contends, “and substantially richer in carbon dioxide.” Dyson calls ocean acidification, which many scientists say is destroying the saltwater food chain, a genuine but probably exaggerated problem. Sea levels, he says, are rising steadily, but why this is and what dangers it might portend “cannot be predicted until we know much more about its causes.”
Given that Dyson accepts the basic science of global warming, how — despite all his brilliance — is his opinion on the effects of warming worth any more than anyone else’s?