Table 1 Summary of this work’s bottom-up estimates of CH4 emissions from the U.S. oil and natural gas (O/NG) supply chain (95% confidence interval) and comparison to the EPA Greenhouse Gas Inventory (GHGI).

Industry segment2015 CH4 emissions (Tg/year)
This work (bottom-up)EPA GHGI (17)
Production7.6 (+1.9/−1.6)3.5
Gathering2.6 (+0.59/−0.18)2.3
Processing0.72 (+0.20/−0.071)0.44
Transmission and storage1.8 (+0.35/−0.22)1.4
Local distribution*0.44 (+0.51/−0.22)0.44
Oil refining and transportation*0.034 (+0.050/−0.008)0.034
U.S. O/NG total13 (+2.1/−1.7)8.1 (+2.1/−1.4)

*This work’s emission estimates for these sources are taken directly from the GHGI. The local distribution estimate is expected to be a lower bound on actual emissions and does not include losses downstream of customer meters due to leaks or incomplete combustion (materials and methods, section S1.5).

†The GHGI only reports industry-wide uncertainties.