The unintended benefits of pollution rules

MIT researchers find China’s new SO2 and NOx regulations will also reduce CO2 emissions

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Alli Gold Roberts, MIT Joint Program on the Science and Policy of Global Change

China's unprecedented growth has created more demands on energy.

China's unprecedented economic growth has created a more affluent society that demands more energy. The current growth is leading to more emissions from power plants and industries, which threaten human health, the economy and the environment. Government officials recognize the severity of the problem and have taken action through a series of policy initiatives in the 12th Five-Year Plan (2010-2015).

"Power plants, factories and vehicles have all increased sulfur dioxide (SO2) and nitrogen oxide (NOx) pollution, which cause smog and acid rain and lead to health effects such as heart disease, asthma and shortened lifespans," says Kyung-Min Nam, a researcher in MIT's Joint Program on the Science and Policy of Global Change. "The increased stringency of new pollution controls reflects a growing recognition of the public health, economic and environmental costs of air pollution in China."

SO2 and NOx are byproducts of the burning of fossil fuels and other activities that cause CO2 emissions, so limiting these pollutants can also reduce CO2 emissions. Nam and his colleagues wanted to research effective ways for policymakers to reduce air pollution and mitigate carbon emissions, given the potential interactive effects of these policies.

In a study published this week in Global Environmental Change, they evaluated the unintended CO2 emissions reductions in the new SO2 and NOx regulations in China's 12th Five-Year Plan. They found that the tighter SO2 and NOx regulations would reduce CO2 enough to allow China to surpass its 2015 goals—by a substantial margin.

"It is clear that the unintended benefits of the regulations are substantial and would allow the government to improve air quality, while also cutting the most potent greenhouse gas. We have also learned that carbon emissions may not rise as high as some forecasts suggest, if concerns about conventional pollutants lead to air pollution reduction policies," Nam says.

In the 12th Five-Year Plan, the Chinese government committed to reduce SO emissions by eight percent and NO emissions by 10 percent from 2010 levels. In addition, the government established a target to reduce CO2 intensity by 17 percent from the 2010 level. The researchers found that by 2015 the SO2 and NOx regulations could reduce CO2 intensity by 20 percent, exceeding China's official goal.

Valerie Karplus, a co-author of the study and the director of the MIT Joint Program's China Energy and Climate Project, says, "Considering that the current CO2 target can be attained by the secondary benefits of the SO2 and NOx regulations, policymakers would do well to coordinate the regulatory efforts. Currently, they have room to adopt more ambitious CO2 reduction policies, but the impact will hinge on effective implementation."

The researchers also estimate that the regulations have the potential to save the Chinese economy $3 billion, the estimated costs of compliance with the CO2 intensity targets.

"We find that China can meet its short-term pollution goals and still expand the use of coal. However, continued use of coal will ultimately make future emissions reductions excessively expensive. The government can achieve greater cost savings for industry by choosing policies that require earlier action and investment in long-term reduction goals," Nam says. "This emphasizes the need for a forward-looking approach that anticipates more significant reductions in the future and includes cleaner technologies in the near term."

Nam plans to continue this research by extending the modeling to the U.S. He will compare the unintended benefits of both pollution and climate regulations in China and the U.S. and quantify the interactive effects in both directions.