Hybrid bottom-up and top-down framework resolves discrepancies in Canada’s oil and gas methane inventories

Abstract Estimating accurate oil and gas methane emissions has been a global challenge, highlighted by a twofold discrepancy between atmospheric measurement-based estimates and emission inventories. The principle of continuous improvement in Canada’s National Inventory Report has led to an unstable baseline in recent years for tracking emission reduction progress. The gaps between previous inventory estimates and inversions exceeded 60%. Here we show that incorporating new source-resolved information derived from low-altitude aerial survey data has narrowed this gap by 80%, reducing the discrepancy to 10% for the 2010–2014 baseline. This study proposes a hybrid emission reporting framework, complemented by an ensemble inversion top-down method using continuous tower-based atmospheric measurements, to establish a stable baseline and provide independent verification. As the 2030 target year for emission reduction approaches, we report a significant 27% decline (19%–34%) in inverse oil and gas methane emissions from 2010 to 2022 in Alberta and Saskatchewan, Canada, and a 41% decline (26%–56%) as calculated using the 2024 official inventory.