William Happer, Emeritus Professor of Physics, Princeton University: The best way to think about the frenzy over climate is to consider it a modern version of the medieval Crusades. You may remember that the motto of the crusaders was “Deus vult!”, “God wills it!” After decades of propaganda, many Americans think there really is a climate emergency. Those who think that way, in many cases, mean very well. But they have been misled. Hare-brained schemes to limit emissions of CO2, which is actually beneficial, will only make it harder to get rid of real pollutants that exist in China and elsewhere.