RON BAILEY: Earth Day Turns 40. “Obviously, Nelson’s dour pollution predictions did not materialize. We don’t wear gas masks or live in domed cities. Since 1980, ambient concentrations of the six major regulated air pollutants have dropped by 54 percent, while U.S. population grew 34 percent, energy use increased 32 percent, automobile miles nearly doubled, and GDP rose by 126 percent. Specifically, ambient carbon monoxide is down 79 percent; ozone down 25 percent; nitrogen dioxide down 46 percent; sulfur dioxide down 56 percent, particulates down 68 percent. . . . The environmental degradation that rightly concerned Nelson and other early environmentalists occurred in open access commons—areas where no one owned the resource and so had no incentive to protect and conserve it. Instead, the incentive of people operating in an open access commons is to grab as much as possible as quickly as possible because otherwise someone else will take it before they can. Thus airsheds, rivers, government forests, oceans, and even highways were polluted and degraded. Relying on this insight, I hope that future environmentalists will find that enclosing the commons, rather than using the blunt instrument of political regulation, will more effectively protect and restore the natural world.”