Canada's Landfill Methane Inventories: The Challenge of Accurate Modeled and Measurement-Based Emissions

We present a measurement-based assessment of methane emissions from 42 landfills across diverse climatic regions in Canada. Our findings reveal that emission rates predicted by the First Order Decay (FOD) model used by Environment and Climate Change Canada at the visited sites are substantially higher than most measured emission rates, on average by a factor of 3, particularly for cold and arid climates typical of the Canadian prairie provinces (by a factor of 13 on average). Bias-corrected measurement rates aligned more closely with values reported to the Canadian Greenhouse Gas Reporting Program. Compared to the amounts estimated by the FOD model, our measurement-based estimations show greater variation with changes in climate. At some warmer and wetter sites, measured rates exceeded FOD modeled estimates, underscoring the influence of climate on landfill methane dynamics and FOD model behavior. We also found that measurement-based estimates yield more realistic methane collection effectiveness values than those implied by Canada’s FOD-based inventories. Our results suggest that current FOD inventory model parameters—that include decay rates and oxidation assumptions—should be refined to better reflect site-specific and climate variability.