Offshore and urban methane emissions in Gabon

Atmospheric CH4 mole fractions have strongly increased since 1750 due to human activity and continue to rise. Reducing CH4 emissions is often easily feasible and also economically interesting, especially from fossil fuel sources (e. g. leakages). For the development of effective reduction strategies and to prioritize actions, CH4 emissions, their spatial distribution and their variability must be well constrained. This study presents airborne top-down emission estimates from Gabonese offshore oil installations as well as emissions from the Libreville urban area. A correlation with installation age and oil production is discussed, and a comparison with reported data and other top-down studies is presented. Further, co-emitted species such as C2H6, CO2, CO and NOy are shown for both offshore fossil fuel sources and the mixture of different urban sources, which include contributions from fossil fuel and biogenic origins (e.g. landfills).