Research Brief: Urban and Landfill Methane Emissions

The Harvard Methane Initiative has released a new research brief, summarizing research on quantifying methane emissions from urban areas and estimating the contribution to these emissions from various source sectors.

You may preview and download the brief at the bottom of this page.

Urban areas are a major source of population-driven methane emissions, but quantifying these emissions and estimating the contribution from different source sectors remains a challenge. This study uses satellite observations of atmospheric methane concentrations and a high-resolution (12 kilometer by 12 kilometer) inversion framework to estimate methane emissions from 12 major U.S. urban areas and from 53 large individual landfills. The authors find substantial discrepancies between their results and the emissions previously reported for urban areas using bottom-up estimation methods.

Overall, their analysis points to substantial underestimation of urban methane emissions in bottom-up inventories, with an estimate of total emissions for the 12 areas studied that is 80% higher than currently reflected in the U.S. Environmental Protection Agency’s national Greenhouse Gas Inventory. Undercounting of landfill emissions appears to be a principal cause of this discrepancy, likely because current reporting methods overstate the real-world performance of landfill gas collection and control systems.

An exception is Los Angeles, where the inversion analysis indicates that landfill gas collection efficiencies are far higher than in other areas. This finding suggests large potential to mitigate urban methane emissions through improved landfill management.

Reference to full paper and acknowledgements

A more detailed account of the research on which this brief is based may be found in Xiaolin Wang, Daniel J. Jacob, Hannah Nesser, Nicholas Balasus, Lucas A. Estrada, Melissa P. Sulprizio, Daniel H. Cusworth, Tia R. Scarpelli, Zichong Chen, James D. East, and Daniel J. Varon. “Quantifying Urban and Landfill Methane Emissions in the United States Using TROPOMI Satellite Data.” Science Advances 12 (13). March 2026. eadz9308. https://doi.org/10.1126/sciadv.adz9308.

Xiaolin Wang is a Postdoctoral Fellow in Environmental Science and Engineering at Harvard University.

Marika Tatsutani is a science writer based near Boston, Massachusetts.

This work was funded by the Harvard Methane Initiative and by the NASA Carbon Monitoring System under grant no. 80NSSC25K7208. H.N. acknowledges support from an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by Oak Ridge Associated Universities under contract with NASA.

This publication was designed by Bryan Galcik.