Constructing a gridded inventory based on Mexico’s National Inventory of Greenhouse Gases and Compounds for evaluation of Mexico’s anthropogenic methane emissions

Abstract:

Under the Paris Agreement and the North American Climate, Clean Energy, and Environment Partnership, Mexico has committed to reduce its methane emissions and has established national regulations to curb methane emissions from the oil and gas industry. The National Inventory of Greenhouse Gases and Compounds constructed by the Instituto Nacional de Ecología y Cambio Climático (INECC) is used to track progress toward emission reduction goals, but the inventory is limited to national information and has large uncertainties for oil and gas emissions. We create a gridded inventory for 2015 with 0.1° x 0.1° resolution (≈ 10 x 10 km²) by spatially allocating the detailed sectoral emissions in Mexico’s national inventory using an ensemble of national geospatial datasets, including facility and municipal scale information. We find that emissions are highest in central Mexico and along the east coast, with 51% of oil/gas emissions occurring offshore. These spatial patterns in our bottom-up estimate of emissions can be confronted with top-down atmospheric observations with the goal of evaluating the national inventory, and thereby, improving our ability to track the effectiveness of current regulations in reducing emissions. We also identify 16 hotspots on the 0.1° x 0.1° grid with individual emissions higher than 20 Gg a^-1 (2.3 tons h^-1) including large landfills, offshore oil production, coal mines in northern Mexico, a gas processing complex, and a cattle processing facility. We use fine scale methane observations from TROPOMI and GHGSat-C1 to verify the existence of these potential large emission sources, providing support for Mexico’s regulations requiring large facilities to report emissions.