Climate Benefits of U.S. EPA Programs and Policies That Reduced Methane Emissions 1993-2013

摘要

The United States (U.S.) Environmental Protection Agency (EPA) has established voluntary programs to reduce methane (CH_4) emissions, and regulations that either directly reduce CH_4 or provide co-benefits of reducing CH_4 emissions while controlling for other air pollutants. These programs and regulations address four sectors that are among the largest domestic CH_4 emissions sources: municipal solid waste landfills, oil and natural gas, coal mining, and agricultural manure management. Over the 1993-2013 time period, 127.9 Tg of CH_4 emissions reductions were attributed to these programs, equal to about 18% of the counterfactual (or potential) domestic emissions over that time, with almost 70% of the abatement due to landfill sector regulations. Reductions attributed to the voluntary programs increased nearly continuously during the study period. We quantified how these reductions influenced atmospheric CH_4 concentration and global temperature, finding a decrease in concentration of 28 ppb and an avoided temperature rise of 0.006 ℃ by 2013. Further, we monetized the climate and ozone-health impacts of the CH_4 reductions, yielding an estimated benefit of $255 billion. These results indicate that EPA programs and policies have made a strong contribution to CH_4 abatement, with climate and air quality benefits.