Estimates of urban fossil fuel CH4 emissions in the studies indicate that noteworthy proportions of delivered natural gas are being lost to the atmosphere . Figure shows urban natural gas loss rates reported in the studies for select U.S. cities. We combined these urban loss rates, which account for CH4 emissions from natural gas distribution and end-use, with loss rate estimates for the upstream and midstream natural gas supply chain segments to estimate a total supply chain loss rate. The loss rates for the individual segments in Figure can be interpreted as the amount (expressed as a percentage) of CH4 emitted relative to total produced (e.g., , throughput, or delivered/consumed natural gas. We included the Oil and Gas Climate Initiative's (OGCI's) target loss rate of 0.2% for the upstream segment in Figure to demonstrate the effect reducing upstream CH4 losses has on the total supply chain loss rate. Figure . Natural gas loss rates for different supply chain segments. Estimates for downstream loss rates were extracted from the studies and thus account for CH4 emissions from distribution and end-use (i.e., total urban natural gas CH4 emissions). Loss rates for the upstream and midstream segments were extracted from . The Oil and Gas Climate Initiative's (OGCI's) target loss rate of 0.2% for the upstream segment is included as an alternative to Alvarez et al. ( ) to demonstrate the effect upstream CH4 emissions reductions have on the total supply chain loss rate. To visualize this effect, readers should eliminate the dashed bar sections in the figure. Uncertainties are the sum of downstream (if reported) and midstream uncertainties. The abbreviations for cities/urban regions on the x-axis are SFBA -San Francisco Bay Area, WSH, DC -Washington, District of Columbia, BLT -Baltimore, LA -Los Angeles, and BOS -Boston. In Figure , the mean downstream loss rate reported in the studies was 1.8% (± 0.9%). The lowest and highest downstream loss rates were reported for SFBA (0.4% ± 0.1%; and Los Angeles (3.5%; . On average, the downstream losses in Figure are responsible for 41.6% (± 14.2%) of the total natural gas supply chain loss rate. Notably, the downstream loss rates estimated for Boston and two out of the five estimates for Los Angeles are > 50% of the total supply chain loss rate. Downstream loss rates reported for Washington, DC and Baltimore and Los Angeles are generally comparable. estimated a downstream loss rate for Los Angeles two times greater than but for a slightly longer period. The TD estimates of CH4 emissions used to calculate the loss rate in are larger than those reported in , possibly due to a slight difference in the methods used to estimate emissions between the studies. Both studies used the tracer scaling quantification method, but accounted for seasonal variability in the Los Angeles CO2 flux whereas did not. We note that the loss rate for for the Washington, DC/Baltimore region is the average of two estimates over winter 2015 (1.1% ± 0.6%) and 2016 (2.1% ± 1.0%). Seasonally higher natural gas emissions in winter and timing of the measurements could explain why this loss rate is higher relative to others reported for the same region . In SFBA and Washington, DC and Baltimore , the upstream sector dominates total supply chain losses using the Alvarez et al. ( ) loss rate for this segment.