Later this century, sometime toward my teenage son’s late middle age, climate change might torch 50 percent of the world’s gross domestic product. I’ll say that again. Sometime around 2070–2090, climate change could be doing so much damage to ecological and human systems, and the links between them, that the global economy could contract by half. (For comparison: The U.S. economy shrank by roughly 30 percent in the Great Depression.) According to the U.K. Institute and Faculty of Actuaries , it