2012] concluded that the CH4 emissions in the L.A. region had a stable isotope ratio similar to that of fossil-fuel CH4. This ... 2012], we find that natural gas leaks from the SoCalGas and in-home pipelines are not the only possible source of fossil fuel ... 2012] with the CARB GHG inventory by noting that fossil fuel CH4 emissions predominate in the western basin and that landfill ... fossil fuel emissions, J. Geophys. Res., 117, D07308, doi:10.1029/2011JD016826. * Trainer, M., B. A. Ridley, M. P. Buhr, G. Kok ...