The Motivation Behind This Study

A persistent problem in oil and gas methane emission reporting is the nearly twofold discrepancy between methane emission estimates derived from atmospheric measurements (top-down) and those reported in official national inventories (bottom-up). This gap has sparked intense investigations within the scientific community, with peer-reviewed articles consistently highlighting the uncertainties and questioning the credibility of emission trends over the past two decades.

Our study aims to address this discrepancy. In early 2024, Environment and Climate Change Canada (ECCC) integrated low-altitude aerial survey data into the national oil and gas methane inventories submitted to the UNFCCC. This integration represented a significant leap forward, incorporating new science and data sources to refine our understanding and quantification of methane emissions in the oil-and-gas sector.

Figure shows oil pads (left) and oil/gas facilities (right) in Western Canada. Photos by Google Earth.

Photo shows a big crowd of methane experts gathering at the CanCH₄ symposium held at Carleton University in May 2024.

From left to right in the photo: Dr. Johnson of Carleton University, who conducted aerial surveys in Western Canada to help improve the oil and gas methane inventories; Mr. Barrigar of ECCC, a co-author of this study from the national inventory team; Dr. Vogel of ECCC, a co-author of this study from the atmospheric science team; and Dr. Liggio, a research scientist at ECCC who provided valuable comments to enhance the manuscript.

Advancing Our Approach to Methane Emission Estimations

Over the years, our team of atmospheric scientists has been enhancing inversion methods to estimate methane emissions independently from the inventory team. By incorporating multiple atmospheric transport models, emission maps, and optimization procedures into an ensemble, the goal is to produce robust estimates and more realistic quantifications of uncertainties. It is like piecing together a complex puzzle—using as many pieces as possible to ensure an accurate picture. The capability of these models to simulate observed variability in atmospheric methane concentrations is central to improving these estimates.

Our colleagues at ECCC’s Inventory Division have made significant progress in enhancing the consistency and accuracy of methane inventories, incorporating data from aerial surveys conducted by the Energy and Emissions Research Laboratory at Carleton University. As atmospheric scientists at ECCC, we complement this effort by providing independent emission estimates derived from long-term, systematic, ground-based measurements. These high-accuracy, high-precision continuous measurements have been collected for decades across Canada, offering a valuable benchmark for informing policies. Our collaborative work fosters a robust system that allows for cross-checking between inventory- and measurement-based estimates.

Figure shows the long-term greenhouse gas (GHG) monitoring sites operated by Environment and Climate Change Canada. Many of these sites have been collecting atmospheric GHG data for over 10 years. Some sites have over 30 years of data records.

Photos show a tall tower (left) and equipment (right) used for measuring greenhouse gas concentrations (mole fractions) in the atmosphere. Zooming in on the left panel, field operators can be seen climbing the tower for routine maintenance.

A Paradigm Shift: Introducing a Hybrid Framework

This study represents more than a scientific advancement; it marks a paradigm shift in how methane emission estimates are reported and verified. Rather than merely highlighting discrepancies, we demonstrate an integrative approach to developing a new measurement-based national inventory. For the first time in Canada, inventory specialists and atmospheric scientists have collaborated to develop a hybrid framework for methane emission monitoring and reporting in the oil-and-gas sector and co-author a scientific paper—an achievement we are excited to share!

By integrating diverse information and expertise—industry-reported data, aerial surveys, long-term ground-based atmospheric measurements, and atmospheric transport models—we have improved the accuracy of the oil and gas methane inventories and demonstrated the critical importance of independent verification. This hybrid approach provides continuous feedback for current and future regulations, aiming to close the gap between inventory- and measurement-based estimates in Canada’s oil-and-gas sector.

Looking to the Future

Our hope is that this study sparks meaningful dialogue and action among the research community, inventory reporting agencies, and policymakers. By working together, we can support efforts to reduce methane emissions as we approach key climate targets, such as those set for 2030.

This journey of collaboration and scientific rigor underscores the urgency and importance of finding new ways to accurately, transparently, and consistently quantify and track methane emissions. We believe that these efforts will ultimately contribute to a more sustainable future, where methane’s role in climate change is better understood and managed.