#3. Southern California Forest Fires

California has been ravaged by wildfires for thousands of years; they're an essential part of the natural ecosystem. But the fires that burned hundreds of square miles between Oct. 20 and Nov. 6 — at the disaster's peak, 18 separate fires were burning, the worst of them in San Diego County — killing 10 people and forcing at least half a million more from their homes, weren't entirely natural. At least one, the Santiago Canyon blaze, was deliberately set, while two others — the Witch and Rice Canyon fires — were caused by downed power lines that ignited surrounding brush. Whether that brush should have been more thoroughly cleared, and whether people should be permitted to build homes in remote, fire-prone areas, are now matters of active debate, to say nothing of lawsuits.