A new report on abrupt climate change doesn’t necessarily say the sky is falling but portrays a complex world that it is clearly undergoing great change. Some change has been wrought by humans and some seems unrelated to our presence on the planet. The Southwest may be drying up, although we didn’t necessarily do it. Greenland and Antarctica are melting; we didn’t necessarily do it but we are certainly contributing. Warm, salty currents in the Atlantic Ocean that circulate heat probably won’t collapse this century, but they could. And the catastrophic methane release some scientists have predicted is unlikely to happen anytime soon, but methane, a greenhouse gas significantly more potent than carbon dioxide, will surely continue to increase in the atmosphere.