Rep. Alexandria Ocasio-Cortez claims that “the world is going to end in 12 years if we don’t address climate change.” The people at the Intergovernmental Panel on Climate Change agree, saying that to avoid some of the most devastating impacts of climate change, the world must slash carbon emissions by 45 percent by 2030 and completely decarbonize by 2050. Such dire warnings are not new. In 1970, Harvard University biology professor George Wald, a Nobel laureate, predicted, “Civilization will end within 15 or 30 years unless immediate action is taken against problems facing mankind.” Also in 1970, Paul Ehrlich, a...