Like a hurricane or a trip to the frontlines of a war, seeing an oil spill up close is something you never forget. In 2010, a few days after the Deepwater Horizon blowout in the Gulf of Mexico that sent 4.9 million barrels of oil into the Gulf, I boarded a small plane and flew out over the still-burning wellhead. It was an apocalyptic sight: flames shooting into the sooty sky, oil shimmering on the water for miles in every direction. A few days later, as the oil started to wash up on shore, I walked along the coast in Grand Isle, Louisiana. “On the worst days, the oil flowed up on the beaches in ribbons, sticking to the sand like big black cobwebs,” I wrote. “The smell was bad, too – a heavy, metallic, stomach-churning odor of volatilizing chemicals, of benzene and polycyclic aromatic hydrocarbons. It was the smell of cancer.” Later, while I was out on a small boat, a pod of dolphins surfaced in the middle of an oil slick nearby. I could actually hear them coughing.