Satellite Data Reveals 10% Rise in Urban Methane Emissions Despite Climate Pledges

Urban methane emissions, which represent approximately 10% of the global methane budget, rose by about 10% from 2020 to 2023, according to a new analysis of satellite data published in the Proceedings of the National Academy of Sciences of the United States of America. This increase occurred despite cities’ pledges to reduce such emissions.

Methane is a potent greenhouse gas with a shorter atmospheric lifespan than carbon dioxide. Reducing methane emissions could deliver significant short-term climate benefits. While oil and gas operations and agriculture are major methane sources, cities and their infrastructure also contribute substantially through wastewater treatment plants, landfills, and leaky natural gas systems.

Monitoring Methane from Space

“Cities have started attempting to reduce their methane emissions, and we hope to be able to monitor this,” said Erica Whiting, a graduate student in climate and space science at the University of Michigan. Historically, urban methane tracking relied on ground-based measurements and activity-based inventories. Most studies focused on a limited number of cities, primarily in North America and Europe.

Whiting’s team conducted one of the first studies to use satellite data to monitor urban methane emissions over time. Satellite monitoring provides long-term, often global, measurements, offering a clearer view of mitigation progress.

Cities Fall Short on Methane Reduction Goals

A growing number of cities are targeting carbon emission reductions, but the new data indicate many are not on track. The study analyzed 92 cities worldwide, including 51 members of the C40 coalition, a 96-country alliance founded in 2005. The coalition aims to halve greenhouse gas emissions by 2030, including a 34% reduction in methane emissions, aligning with the goal of limiting global warming to 1.5°C above preindustrial levels.

The researchers used methane data from the TROPOMI (Tropospheric Monitoring Instrument), a satellite-based sensor launched in 2017. TROPOMI enables continuous global monitoring of methane and other gases. Data from 2019 to 2023 showed urban methane levels initially declined from 2019 to 2020. However, emissions rose by 10% in C40 cities and 12% in non-C40 cities from 2020 to 2023.

The study examined not only urban centers but also surrounding areas, where methane sources like landfills and wastewater treatment plants are often located. The TROPOMI instrument aboard the Sentinel-5P satellite detects methane concentrations, with higher levels shown in warmer colors in urban snapshots. Credit: Erica Whiting.

Unclear Causes Behind Rising Emissions

While the study cannot definitively explain the trends, Whiting noted that urban populations grew during the period, which may have contributed to the increase. “In most regions…”