Sept. 23, 2013
A new study finds that reducing greenhouse gas emissions – key to slowing global climate change – also will decrease outdoor air pollution and may save the lives of more than two million people annually in the future. Further, when examined in monetary terms, these benefits to human health are shown to outweigh the implementation costs of reducing the greenhouse gas emissions through at least 2050.
Dr. Jason West

Dr. Jason West

The study, led by Jason West, PhD, assistant professor of environmental sciences and engineering at the UNC Gillings School of Global Public Health, was published online Sept. 22 in Nature Climate Change.  

The authors used computer models to compare two possible future scenarios – one in which there is no climate policy and one with policies that aggressively reduce greenhouse gas emissions from all nations and all economic sectors.

In the simulations, the actions taken to reduce greenhouse gas emissions were found to avoid approximately one-half million premature deaths related to air pollution globally per year in 2030, about 1.3 million in 2050, and about 2.2 million in 2100.  The co-benefits of these avoided deaths are estimated to be between $50 and $380 per ton of carbon dioxide reduced, globally averaged, which are greater than the costs of implementing the reductions in 2030 and 2050.

Air quality “co-benefits” result mainly from reductions in air pollutant emissions from the same sources that emit greenhouse gases.  For example, replacing a coal-fired power plant with a renewable electricity source, such as wind power, reduces both air pollutant and greenhouse gas emissions.  

The current study is the first to use a global atmospheric model and consistent future scenarios to estimate co-benefits, to air pollution and human health, of global greenhouse gas reductions.  The authors combined a global energy-economics model with a model of the global atmosphere, and methods of assessing human health impacts.  In doing so, they translated energy use to emissions to atmospheric concentrations, and then to human health effects and monetized benefits.  

The study uses state-of-the-art methods to account for several influences – growth in global population, economic activity and susceptibility to air pollution, long-range transport of air pollution, and the effect of climate change on air quality.  By accounting for all of these influences, co-benefits are estimated to be markedly higher than previous studies had found.

Co-benefits are estimated in each world region, with especially high co-benefits found in densely-populated regions such as East Asia, South Asia, North America and Europe.  

“Our findings in East Asia are particularly striking,” West said. “China has a large population exposed to some of the world’s worst air pollution.  We estimate that the air quality and health co-benefits in East Asia in 2030 are 10 to 70 times the cost of reducing greenhouse gas emissions.”

These findings suggest that including air pollution and health co-benefits could significantly increase estimates of the value of reducing greenhouse gas emissions, strengthening the case for taking action.  They further suggest that policies should be better coordinated to address the challenges of climate change and air quality simultaneously.  

“The world has been slow to adopt significant actions to address climate change, as it is a long-term and global problem,” West said.  “The benefits of reducing carbon dioxide today are felt in the future, and since they occur globally, countries may take little action and rely on others to lead.  On the other hand, better air quality and improved health are realized rapidly and locally, providing government leaders with tangible benefits from their actions to reduce carbon dioxide.”

UNC co-authors include Meridith Fry, PhD, recent environmental sciences and engineering alumna at the Gillings School, and Zachariah Adelman, Raquel A. Silva and Yuqiang Zhang, environmental sciences and engineering doctoral students.

Other co-authors are Steven J. Smith, PhD, of the Joint Global Change Research Institute, Pacific Northwest National Laboratory, in College Park, Md.; Vaishali Naik, PhD, and Larry Horowitz, PhD, of the NOAA Geophysical Fluid Dynamics Laboratory, in Princeton, N.J.; Susan Anenberg, PhD, Gillings School alumna and environmental scientist at the U.S. Environmental Protection Agency, in Washington, D.C., and Jean-Francois Lamarque, of the National Center for Atmospheric Research, in Boulder, Colo.

The paper, “Co-benefits of Mitigating Global Greenhouse Gas Emissions for Future Air Quality and Human Health,” is available online. The research was funded partially by the U.S. Environmental Protection Agency and the National Institutes of Health’s National Institute of Environmental Health Sciences (NIEHS).

Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or
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