“How dare you? You have stolen my dreams and my childhood!” insisted teenage climate activist Greta Thunberg at the United Nations. “We are in the beginning of a mass extinction!” Many people say that we’re destroying the Earth. It all sounds so scary. But I’ve been a consumer reporter for years, and I’ve covered so many scares: plague, famine, overpopulation, SARS, West Nile virus, bird flu, radiation from cellphones, flesh-eating bacteria, killer bees, etc. The list of terrible things that were going to get us is very long. Yet we live longer than ever. Now I’m told global warming is...