The North American Greenhouse Gas Budget: Emissions, Removals, and Integration for CO2, CH4, and N2O (2010–2019)

Greenhouse gas emissions for North America show large disagreement between top down and bottom up methodologies. As part of the REgional Carbon Cycle Assessment and Processes study (RECCAP2) we evaluated these sources of disagreement using atmospheric inversions, process models, and national greenhouse gas inventories. We found that for the period 2010–2019, the national greenhouse gas inventories reported total net-GHG emissions of a source of 7,270 TgCO₂-eq yr⁻¹ compared to top down estimates of 6,132 ± 1,846 TgCO₂-eq yr⁻¹ and bottom up estimates of 9,060 ± 898 TgCO₂-eq yr⁻¹.  The differences between the estimates are from a combination of uncertainties in emissions and removals, but also due to definitions used to account for anthropogenic versus natural emissions or both, including the use of the managed land proxy, and the role of the land ocean aquatic continuum (LOAC). Reconciling net emissions between methodologies is partly achievable after accounting for these methodological and definition-based differences.