Despite its key role in climate change, large uncertainties persist in our knowledge of the anthropogenic emissions of carbon dioxide () and no global observing system exists that allows us to monitor emissions from localized sources with sufficient accuracy. The Orbiting Carbon Observatory-2 (OCO-2) satellite allows retrievals of the column-average dry-air mole fractions of (). However, regional column-average enhancements of individual point sources are usually small, compared to the background concentration and its natural variability, and often not much larger than the satellite's measurement noise. This makes the unambiguous identification and quantification of anthropogenic emission plume signals challenging. is co-emitted with when fossil fuels are combusted at high temperatures. It has a short lifetime on the order of hours so that columns often greatly exceed background and noise levels of modern satellite sensors near sources, which makes it a suitable tracer of recently emitted . Based on six case studies (Moscow, Russia; Lipetsk, Russia; Baghdad, Iraq; Medupi and Matimba power plants, South Africa; Australian wildfires; and Nanjing, China), we demonstrate the usefulness of simultaneous satellite observations of and . For this purpose, we analyze co-located regional enhancements of observed by OCO-2 and from the Sentinel-5 Precursor (S5P) satellite and estimate the plume's cross-sectional fluxes. We take advantage of the nearly simultaneous measurements with S5P's wide swath and small measurement noise by identifying the source of the observed enhancements, excluding interference with remote upwind sources, allowing us to adjust the wind direction, and by constraining the shape of the plumes. We compare the inferred cross-sectional fluxes with the Emissions Database for Global Atmospheric Research (EDGAR), the Open-Data Inventory for Anthropogenic Carbon dioxide (ODIAC), and, in the case of the Australian wildfires, with the Global Fire Emissions Database (GFED). The inferred cross-sectional fluxes range from 31 Mt a to 153 Mt a with uncertainties (1) between 23 % and 72 %. For the majority of analyzed emission sources, the estimated cross-sectional fluxes agree, within their uncertainty, with either EDGAR or ODIAC or lie somewhere between them. We assess the contribution of multiple sources of uncertainty and find that the dominating contributions are related to the computation of the effective wind speed normal to the plume's cross section. The flux uncertainties are expected to be reduced by the planned European Copernicus anthropogenic monitoring mission (CO2M), which will provide not only precise measurements with high spatial resolution but also imaging capabilities with a wider swath of simultaneous and observations. Such a mission, particularly if performed by a constellation of satellites, will deliver emission estimates from localized sources at an unprecedented frequency and level of accuracy.