Earth Systems

Health Co-Benefits of Sub-National Renewable Energy Policy in the U.S.

Summary: Amid rollbacks of the Clean Power Plan and other environmental regulations at the federal level several U.S. states, cities and towns have resolved to take matters into their own hands and implement policies to promote renewable energy and reduce greenhouse gas emissions.  One popular approach, now in effect in 29 states and the District of Columbia, is to set Renewable Portfolio Standards (RPS), which require electricity suppliers to source a designated percentage of electricity from available renewable power generating technologies.

Boosting levels of renewable electric power not only helps mitigate global climate change but also reduces local air pollution. Quantifying the extent to which this approach improves air quality could help legislators better assess the pros and cons of implementing policies such as RPS. Toward that end, a research team at MIT has developed a new modeling framework that combines economic and air-pollution models to assess the projected sub-national impacts of RPS and carbon pricing on air quality and human health, as well as on the economy and on climate change. In a study focused on the U.S. Rust Belt, their assessment showed that the financial benefits associated with air quality improvements from these policies would more than pay for the cost of implementing them.

Applying their modeling framework, the MIT researchers estimated that existing RPS in the nation’s Rust Belt region generate a health co-benefit of $94 per ton of carbon dioxide (CO2) reduced in 2030, or 8 cents for each kilowatt hour (kWh) of renewable energy deployed in 2015 dollars. Their central estimate is 34 percent larger than total policy costs. The team also determined that carbon pricing delivers a health co-benefit of $211 per ton of CO2 reduced in 2030, 63% greater than the health co-benefit of reducing the same amount of CO2 through an RPS approach.

Co-benefits of China’s climate policy for air quality and human health in China and transboundary regions in 2030

Summary: Improved air quality can be a major bonus of climate mitigation policies aimed at reducing greenhouse gas emissions. By cutting air pollution levels in the country where emissions are produced, such policies can avoid significant numbers of premature deaths. But other nations downwind from the host country may also benefit. This study hows that if the world’s top emitter of greenhouse gas emissions, China, fulfills its climate pledge to peak carbon dioxide emissions in 2030, the positive effects would extend all the way to the United States, where improved air quality would result in nearly 2,000 fewer premature deaths.       

The study estimates China’s climate policy air quality and health co-benefits resulting from reduced atmospheric concentrations of ozone, as well as co-benefits from reduced ozone and particulate air pollution (PM2.5) in three downwind and populous countries: South Korea, Japan and the U.S. As ozone and PM2.5  give a well-rounded picture of air quality and can be transported over long distances, accounting for both pollutants enables a more accurate projection of associated health co-benefits in the country of origin and those downwind.  

A global 3-D ocean model for polychlorinated biphenyls (PCBs): Benchmark compounds for understanding the impacts of global change on neutral persistent organic pollutants

Human activities have released large quantities of neutral persistent organic pollutants (POPs) that may be biomagnified in food webs and pose health risks to wildlife, particularly top predators. Here we develop a global 3‐D ocean simulation for four polychlorinated biphenyls (PCBs) spanning a range of molecular weights and volatilities to better understand effects of climate‐driven changes in ocean biogeochemistry on the lifetime and distribution of POPs. Observations are most abundant in the Arctic Ocean. There, model results reproduce spatial patterns and magnitudes of measured PCB concentrations. Sorption of PCBs to suspended particles and subsequent burial in benthic marine sediment is the dominant oceanic loss process globally. Results suggest benthic sediment burial has removed 75% of cumulative PCB releases since the onset of production in 1930. Wind speed, light penetration, and ocean circulation exert a stronger and more variable influence on volatile PCB congeners with lower particle affinity such as chlorinated biphenyl‐28 and chlorinated biphenyl‐101. In the Arctic Ocean between 1992 and 2015, modeled evasion (losses) of the more volatile PCB congeners from the surface ocean increased due to declines in sea ice and changes in ocean circulation. By contrast, net deposition increased slightly for higher molecular weight congeners with stronger partitioning to particles. Our results suggest future climate changes will have the greatest impacts on the chemical lifetimes and distributions of volatile POPs with lower molecular weights.

Increase in CFC-11 emissions from eastern China based on atmospheric observations

Summary: The repair of the Earth’s ozone layer, which shields the planet from the sun’s harmful ultraviolet radiation, has long been touted as a global success story. Since the 1987 Montreal Protocol required the phase-out by 2010 of production of ozone-depleting chlorofluorocarbons (CFCs), nearly every nation in the world has complied, putting the ozone layer on track for a complete healing by midcentury. But a new development threatens to delay that happy ending. Recent studies have indicated that atmospheric concentrations of the second-most abundant chlorofluorocarbon, known as trichlorofluoromethane (CFC-11) and primarily used as foaming agent for building insulation, refrigerators and other consumer products, have significantly increased since 2012—and that some of this increase has come from eastern Asia. But this research did not establish the exact location and extent of this regional source of CFC-11 emissions.

Now a new study appearing in the journal Nature pinpoints the primary source of the rise in CFC-11 emissions as the northeastern Chinese provinces of Shandong and Hebei, with these two provinces accounting for at least 40 to 60 percent of the global rise in CFC-11 emissions. An international team comprised of scientists from MIT, University of Bristol and several other research institutions combined high-frequency atmospheric observations from Gosan, South Korea, and Hateruma, Japan, with global monitoring data (from NOAA and AGAGE) and atmospheric chemical transport model simulations to produce these findings.

The team found no evidence of significant increases in CFC-11 emissions from any other eastern Asian countries or other regions where long-term, high-frequency atmospheric data could be obtained. The researchers also deduced that the recent increase in CFC-11 emissions from eastern mainland China is due to new production and use of the banned chemical compound, rather than from increased rates of escape from pre-phase-out banks of CFC-11 in existing foam or refrigerators.

 

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