by Dan Ariely
Nevertheless, Streets considered the endeavor important because China is full of the two biggest contributors to human-generated mercury, metal smelting and coal combustion. Smelting facilities heat metal ores to eliminate contaminants and extract the desired metal, such as zinc, lead, copper, or gold. Unfortunately, one of the consistent contaminants is mercury, and the heating process allows it to escape into the atmosphere in gaseous form. Similarly, coal contains trace amounts of mercury, which is set free during combustion at power plants.
Streets began by studying reports from China’s National Bureau of Statistics. China’s provinces provide the central government with detailed data on industrial production: how much coal they burn, how much zinc they produce, and so on. “China is very good at producing statistical data. It’s not always one hundred percent reliable, but at least it’s a start,” he says. Those statistics help the Chinese government monitor the economy, but for Streets they also quantified China’s mercury-laden raw materials.
The numbers from the statistics bureau told Streets the total amount of mercury that might be emitted, but he also needed to know how much actually made it into the air. To obtain that information, he turned to pollution detectives—a group of professional contacts he had met at conferences, along with graduate students who spent time in his lab. Most of the time, Chinese factories turned these “spies” away. “Factory owners had nothing to gain and a lot to lose,” Streets says. “They were nervous that the results would get leaked to the government.”
Yet some of Streets’s moles got through by guaranteeing that the data would stay anonymous. Once inside, they took samples of raw materials—zinc ore in a smelting facility, for example—and installed chemical detectors in smokestacks. After a few days of data collection, they passed the information to Streets.
The statistics Streets collected were hardly airtight. Factory foremen and provincial officials were not above providing inflated data to make themselves look more productive, and the managers who were willing to let his inspectors take measurements were often the very ones with nothing to hide. “There’s still a lot of uncertainty,” Streets concedes, “but we know more than we did before.”
In 2005 Streets and his team reported their first tally of human-generated mercury emissions in China, for the year 1999. The scientists estimated the amount at 590 tons (the United States emitted 117 tons). Almost half resulted from the smelting of metals—especially zinc, because its ores contain a high concentration of mercury. Coal-burning power plants accounted for another 38 percent of Chinese mercury emissions, and that percentage may be going up. As recently as 2007, China was building two new power plants a week, according to John Ashton, a climate official in the United Kingdom.
Streets’s team published a subsequent inventory estimating that China’s mercury emissions had jumped to 767 tons in 2003. “Mercury emissions in China have grown at about 5 to 6 percent a year,” he says. “It’s pretty much undeniable.”
Streets had shown that China was churning out mercury, but he was left with a big uncertainty: What happened to it on its journey aloft? Finding the answer fell to Hans Friedli, a chemist at the National Center for Atmospheric Research (NCAR) who had spent thirty-three years working for Dow Chemical. Friedli had found his own path into the esoteric world of pollution forensics. Back in the early 1990s, a conversation with his neighbor, an NCAR scientist, sparked an interest in wildfires, a major source of mercury emissions. By 1998 he had a full-time job tracking the toxin for NCAR.
With its copious mercury emissions (not only from industry but also from volcanoes, wildfires, and dust storms), Asia drew Friedli’s interest. China would never allow him to do aerial studies in its airspace, but in 2001 he heard about research flights off the coasts of Japan, Korea, and China designed to track dust particles emanating from the mainland. Friedli convinced the research team to take him along to measure mercury concentrations in the atmosphere. Throughout April 2001, nineteen researchers, professors, and grad students took sixteen flights aboard a cavernous retired Navy C-130 plane custom fitted with nineteen instruments for measuring pollutants like carbon monoxide, sulfur, and ozone.
During each flight, Friedli sat at his station awaiting readouts from his mercury sensor: an intake valve that sucked in air and guided it over a gold cartridge within the plane. Any mercury in the air would be absorbed by the gold. Every five minutes the instrument rapidly heated the gold, releasing any trapped mercury.
Plumes of mercury-laced air near Earth’s surface are mixed with other pollutants, but at 20,000 feet Friedli discovered concentrated mercury plumes soaring eastward toward North America. He concluded that those plumes must have circled the entire globe at least once, releasing more ephemeral pollutants like carbon monoxide, so the mercury stood out even more.
Eager to follow the trail of Asian mercury plumes, Friedli set his sights across the Pacific, off the West Coast of the United States. In a series of eleven research flights in 2002, he identified a plume that looked very much like the ones he’d found near China the year before. Specifically, the plume had a ratio of carbon monoxide to mercury that served as a fingerprint for gases from the same source.
What Friedli detected was just one detail of a much larger picture. Mercury plumes can wobble in latitude and altitude or park themselves in one spot for days on end. Emissions from China—and from the United States, and indeed from every industrial country—feed a network of air currents that, as equal-opportunity polluters, serve up toxic mercury around the world.
Drawing insights from research by Friedli and Streets, Jaffe looked at his data anew. If mercury was arriving from China, he should be able to detect it, yet his operation on Cheeka Peak showed no such signal. Conducting reconnaissance from a plane, he realized why. The peak, at 1,500 feet, was below the mercury plume. Seeking a higher perch, he chose Mount Bachelor, a ski resort in central Oregon at an altitude of 9,000 feet.
In late winter 2004, Jaffe and his students huddled deep in their down jackets, bracing against a bitter gale that buffeted the chairlift ferrying them and their costly equipment to the summit. Inside the mountaintop lodge they installed a small computer lab and extended tubes outside to vacuum up the air. Later that year they conducted a similar experiment in Okinawa, Japan.
Back in Washington, they plotted their analysis of mercury in the air against satellite data showing wind currents. “My hypothesis was that we would see the same chemicals, including the same ratio of mercury to carbon monoxide, from Mount Bachelor and Japan,” Jaffe says. The numbers showed exactly the expected similarity. “This was a real ‘aha’ moment for us, because the two regions were phenomenally close.”
It was the first time anyone had decisively identified Asian mercury in American air, and the quantities were stunning. The levels Jaffe measured suggested that Asia was churning out 1,400 tons a year. The results were a shock to many scientists, Jaffe says, because “they still couldn’t wrap their heads around the magnitude of the pollution and how dirty China’s industry was.” They were only starting to understand the global nature of the mercury problem.
Over the years, Jaffe’s Mount Bachelor Observatory has also monitored many other noxious pollutants wafting across the Pacific. One major category is sulfates, associated with lung and heart disease. When sulfur dioxide exits China’s coal and oil smokestacks, it converts into sulfates in the air. “Sulfates are water-soluble and get removed from the atmosphere relatively quickly, creating acid rain that falls in China, Korea, and Japan,” Jaffe says. Yet some of the sulfates stay aloft, finding their way here and contributing to smog along the West Coast.
Another Chinese import is black carbon, the soot produced by cars, stoves, factories, and crop burning and a major component of Chinese haze. The small diameter of the carbon particles means they can penetrate deep inside the lungs, providing absorption sites for secondary toxins that would otherwise be cleared. This compounds the danger, making black carbon an especially potent risk fact
or for lung disease and premature death.
The biggest pollutant coming out of Asia, at least in terms of sheer mass, could be dust from the region’s swelling deserts. “It’s not a new phenomenon,” Jaffe says, but it has gotten worse with deforestation and desertification caused by poorly managed agriculture. About every three years, a huge dust storm over China sends enormous clouds across the Pacific. “We can visually see it,” Jaffe says. “It usually hangs around for about a week. We’ve tried to quantify how much it contributes to the particulate loading here, and it’s a little under 10 percent of the US standard on average each year. It’s a significant amount.”
Chinese dust has obscured vistas in US national parks, even on the East Coast. The amount of dust is widely variable and can hit rare extreme peaks. The highest level recorded was from a 2001 dust event. “It reached approximately two-thirds of the US air quality standard at several sites along the West Coast,” he reports. One study from Taiwan tracked avian flu outbreaks downwind of Asian dust storms and found that the flu virus might be transported long-distance by air spiked with the dust.
Perhaps the most counterintuitive traveling contaminant is ozone, commonly associated with ground-level pollution in cities. Volatile organic compounds, carbon monoxide, and nitrogen oxides from Asian cars and industry mix in the atmosphere as they cross the Pacific Ocean and convert in sunlight into ozone, a main ingredient in smog, Jaffe explains. When air with high ozone concentrations touches down in North America, it can pose the classic dangers of urban smog: heart disease, lung disease, and death.
Jaffe recently coauthored a paper on Asian ozone coming to America. It found that ozone levels above western North America creep upward every spring. “When air was coming from Asia, the trend was strongest. That was the nail in the coffin,” Jaffe says. “The increase was estimated at 0.5 part per billion [ppb] per year. But that’s huge. In ten years that’s another 5 ppb. Let’s say the EPA orders a 5-ppb reduction and we achieve that, and yet, because of the growing global pool, in ten years that gets wiped out. We’ll have to keep reducing our emissions just to stay even.”
The underlying message of Jaffe’s detective work should not be all that surprising: all of the world’s atmosphere is interconnected. People have accepted this notion when it comes to carbon dioxide or the chemicals that eat away at the ozone layer, but Jaffe is finding that they are still coming to terms with the reality that it applies to industrial pollutants in general.
The fact is, those pollutants are everybody’s responsibility, not just China’s. The EPA has estimated that just one-quarter of US mercury emissions from coal-burning power plants are deposited within the contiguous United States. The remainder enters the global cycle. Conversely, current estimates are that less than half of all mercury deposition within the United States comes from American sources.
Then again, the United States has spent considerable effort over the past half-century trying to clean up its act. China is still much more focused on production. To fuel its boom, China has become a pioneer in wind power but has also begun buying up huge inventories of coal from markets around the world. Streets recently estimated that China’s use of coal for electricity generation will rise nearly 40 percent over the next decade, from 1.29 billion tons last year to 1.77 billion tons in 2020. That is a lot more pollution to come.
“It’s a classic example of a tragedy of the commons,” Jaffe says, referring to a dilemma in which individuals act in their own self-interest and deplete a shared resource. “If twenty people are fishing in the same pond, with no fishing limit, then you catch as many as you can because it will be empty in weeks. Nobody has an incentive to conserve, and the same goes for pollution.”
The discovery of the global mercury cycle underscores the need for an international treaty to address such pollutants. Under the auspices of the United Nations, negotiations have at least begun. Jaffe, Streets, and China’s Xinbin Feng are now consultants to the UN Environment Programme’s Global Partnership on Mercury Atmospheric Transport and Fate Research, which helped contribute data that led to a proposed UN mercury treaty in 2009.
When it comes to some pollutants, China has taken important steps. For instance, recent policies encourage desulfurization and other filtering technology in power plants. But convincing developing nations to move aggressively on mercury may be at least as tough as mobilizing them against carbon emissions. “This is not considered a pollutant that urgently needs to be controlled on the national level,” Feng says. “It’s not fair that you emitted so much mercury and other pollutants when you had the chance to industrialize. You had two hundred years, and now you want to stop other countries from developing too.”
“We need to be concerned,” Jaffe counters in his low-key way. “There is no Planet B. We all live downwind.”
ROBERT KUNZIG
The City Solution
FROM National Geographic
AT THE TIME of Jack the Ripper, a hard time for London, there lived in that city a mild-mannered stenographer named Ebenezer Howard. He’s worth mentioning because he had a large and lingering impact on how we think about cities. Howard was bald, with a bushy, mouth-cloaking mustache, wire-rim spectacles, and the distracted air of a seeker. His job transcribing speeches did not fulfill him. He dabbled in spiritualism; mastered Esperanto, the recently invented language; invented a shorthand typewriter himself. And dreamed about real estate. What his family needed, he wrote to his wife in 1885, was a house with “a really nice garden with perhaps a lawn tennis ground.” A few years later, after siring four children in six years in a cramped rental house, Howard emerged from a prolonged depression with a scheme for emptying out London.
London in the 1880s, you see, was booming, but it was also bursting with people far more desperate than Howard. The slums where the Ripper trolled for victims were beyond appalling. “Every room in these rotten and reeking tenements houses a family, often two,” wrote Andrew Mearns, a crusading minister. “In one cellar a sanitary inspector reports finding a father, mother, three children, and four pigs! . . . Elsewhere is a poor widow, her three children, and a child who had been dead thirteen days.” The Victorians called such slums rookeries, or colonies of breeding animals. The chairman of the London County Council described his city as “a tumour, an elephantiasis sucking into its gorged system half the life and the blood and the bone of the rural districts.”
Urban planning in the twentieth century sprang from that horrified perception of nineteenth-century cities. Oddly, it began with Ebenezer Howard. In a slim book, self-published in 1898, the man who spent his days transcribing the ideas of others articulated his own vision for how humanity ought to live—a vision so compelling that half a century later Lewis Mumford, the great American architecture critic, said it had “laid the foundation for a new cycle in urban civilization.”
The tide of urbanization must be stopped, Howard argued, by drawing people away from the cancerous metropolises into new, self-contained “garden cities.” The residents of these happy little islands would feel the “joyous union” of town and country. They’d live in nice houses and gardens at the center, walk to work in factories at the rim, and be fed by farms in an outer greenbelt—which would also stop the town from expanding into the country. When one town filled to its greenbelt—32,000 people was the right number, Howard thought—it would be time to build the next one. In 1907, welcoming 500 Esperantists to Letchworth, the first garden city, Howard boldly predicted (in Esperanto) that both the new language and his new utopias would soon spread around the world.
He was right about the human desire for more living space but wrong about the future of cities: it’s the tide of urbanization that has spread around the world. In the developed countries and Latin America it has nearly crested; more than 70 percent of people there live in urban areas. In much of Asia and Africa, people are still surging into cities, in numbers swollen by the population boom. Most urbanites live in cities of less than half a million, but big cities have
gotten bigger and more common. In the nineteenth century, London was the only city of more than 5 million; now there are fifty-four, most of them in Asia.
And here’s one more change since then: urbanization is now good news. Expert opinion has shifted profoundly in the past decade or two. Though slums as appalling as Victorian London’s are now widespread, and the Victorian fear of cities lives on, cancer no longer seems the right metaphor. On the contrary: with Earth’s population headed toward 9 or 10 billion, dense cities are looking more like a cure—the best hope for lifting people out of poverty without wrecking the planet.
One evening last March, the Harvard economist Edward Glaeser appeared at the London School of Economics to promote this point of view, along with his new book, Triumph of the City. Glaeser, who grew up in New York City and talks extremely fast, came heavily armed with anecdotes and data. “There’s no such thing as a poor urbanized country; there’s no such thing as a rich rural country,” he said. A cloud of country names, each plotted by GDP (gross domestic product) and urbanization rate, flashed on the screen behind him.
Mahatma Gandhi was wrong, Glaeser declared—India’s future is not in its villages, it’s in Bangalore. Images of Dharavi, Mumbai’s large slum, and of Rio de Janeiro’s favelas flashed by; to Glaeser, they were examples of urban vitality, not blight. Poor people flock to cities because that’s where the money is, he said, and cities produce more because “the absence of space between people” reduces the cost of transporting goods, people, and ideas. Historically, cities were built on rivers or natural harbors to ease the flow of goods. But these days, since shipping costs have declined and service industries have risen, what counts most is the flow of ideas.
