What goes up, the adage has it, must come down. It’s an old law of the universe, and universally recognized. Even so, when in 2004 a professor of atmospheric sciences at Harvard University, Daniel Jacob, published the results of a study of a local weather phenomenon, it surprised many New Englanders. Jacob announced that a plume of polluted air that had been hanging in the region’s skies had drifted all the way from China, barely affected by the moderating and buffeting winds of the jet stream. The smoky cloud’s endurance was bad enough, but it was also full of mercury and other highly toxic materials given off by the burning of coal, among them sulfur dioxide, nitrogen oxide, and sooty particulates.
Two years later, in April 2006, a thick cloud of smoke that had been hanging over heavily industrial northern China blew away, as if unmoored from the earth. It settled over Korea for a few days, enveloping Seoul in a thick blanket, and then sailed across the Pacific, making landfall in California a few days later. The cloud was so thick that satellites could track it from far above the earth, as if it were a landmass. Only when it hit the tall barrier of the Sierra Nevada did the cloud begin to break up, shedding sulfur, mercury, and other byproducts of coal burning into Lake Tahoe.
Coal smoke has been an atmospheric problem for as long as coal has been used as a fuel. Londoners of a certain age still remember the deadly winter inversions that once choked the city in coal smoke and fog, giving rise to the word “smog.” The “forest death” that visited so many Old World woodlands in the 1970s and 1980s was largely the product of the coal-burning industries of northern Europe, just as the “acid rain” of the Eastern Seaboard owed to coal-burning plants there. Recognizing the dangers wrought by coal, the nations of the industrialized world developed filtering systems that scrubbed the smoke emerging from industrial smokestacks, even as most consumers switched over to natural gas and other cleaner heating fuels.
West Palace, Beijing. Photograph by Gregory McNamee.
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