“‘Hope’,” wrote Emily Dickinson, employing scare quotes, “is the thing with feathers.” It’s also the one-stringed lyre that continues to sound, even after Chaos is unleashed. Yet hope is a commodity at a premium in the current climate-change debate, which shuttles between apocalyptic pessimism and urgent, sometimes unreflective, calls to action. Good, then, to have three books that pluck at that fragile string.