THE NEXT time you’re in Los Angeles, take a deep breath. A significant portion of the pollution you’ll breathe into your lungs came from across the Pacific Ocean.
Decades ago, Angelenos’ respiratory tracts may have been burned by the accumulation of local pollutants in and around Southern California’s valleys and basins. Since then, federal and state pollution controls did much to clean up the air. But a study in the Proceedings of the National Academy of Sciences finds that neither federal nor state authorities can as effectively restrain one pollution source: China.
Chinese and American researchers estimated the amount and ultimate destination of smog-forming gases and particulates that Chinese factories pumped out in their production of export goods. Up to a quarter of the sulfate pollution in the western United States wafted over from those factories. Their emissions add a day of substandard air in the Los Angeles area every year.
And those are just the fraction of Chinese emissions associated with world trade. Nations closer to China suffer much more. The health and well-being of many people in many countries, not just those choking on thick, brown air in Beijing, depend on China developing into not merely a great economic power but also one that manages its massive impact on the planet.
Typically, greenhouse gases are thought of as unique among environment-altering emissions, in part because carbon dioxide released anywhere contributes to global warming everywhere. Climate change, then, must ultimately be solved by many nations — particularly the emissions behemoths, the United States and China — moving in the same direction. But there are dozens of cross-border environmental issues, and they will require overcoming global political tensions and short-term economic incentives that discourage different countries from cooperating. The world has already tackled one — the phaseout of emissions that thin the ozone layer — through the highly effective Montreal Protocol. Global leaders have many more to see to.
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