Yale Environment 360: Per Espen Stoknes, a Norwegian psychologist and economist, has been doing a lot of thinking about a question that has bedeviled climate scientists for years: Why have humans so far failed to deal with the looming threat posed by climate change? That question is the focus of his recent book, What We Think About When We Try Not To Think About Global Warming, in which he analyzes what he calls the five psychological barriers that have made it difficult to deal realistically with the climate crisis....