No one can say exactly what it looks like when a planet takes ill, but it probably looks a lot like Earth. Never mind what you've heard about global warming as a slow-motion emergency that would take decades to play out. Suddenly and unexpectedly, the crisis is upon us. From heat waves to storms to floods to fires to massive glacial melts, the global climate seems to be crashing around us. The problem -- as scientists suspected but few others appreciated -- is that global climate systems are booby-trapped with tipping points and feedback loops, thresholds past which the slow...