Hidden Super-Emitters: The Climate Imperative Of Addressing Abandoned Fossil Fuel Infrastructure

Last Updated on: 4th June 2025, 07:02 pm

Methane, long overshadowed by carbon dioxide in global climate discussions, is finally receiving the attention it deserves. Recent research, including a just published critical global inventory, A global inventory of methane emissions from abandoned oiland gas wells and possible mitigation pathways by Lei et al., highlights methane emissions from the millions of abandoned oil and gas wells scattered worldwide. This study provides the first robust estimate, counting approximately 4.5 million abandoned wells globally, the equivalent of nearly one well for every person in New Zealand, each potentially leaking substantial amounts of this potent greenhouse gas into the atmosphere.

While the focus on fossil fuel extraction tends toward active operations, abandoned wells have quietly become a significant climate risk. Methane has a global warming potential 81 times that of carbon dioxide over a 20-year horizon, according to the IPCC’s Sixth Assessment Report. That means even modest leaks from abandoned wells have outsized climate impacts, driving urgency in mitigation efforts. According to Lei and colleagues, these wells collectively release around 400,000 metric tons of methane annually, translating to over 32 million metric tons of CO₂-equivalent each year.

To contextualize the scale, global methane emissions from abandoned oil and gas wells represent around 5% of the roughly 8 million metric tons emitted each year by the U.S. oil and gas sector, the single largest source of fossil fuel-related methane emissions globally.

Over the past several years, I’ve repeatedly highlighted methane’s disproportionately large climate impact and the persistent regulatory neglect surrounding orphaned wells. In numerous analyses, I’ve drawn attention to the deeply flawed economics and governance failures that have allowed oil and gas producers to externalize cleanup costs onto the public. I’ve emphasized the accumulating liabilities in places like Alberta, where tens of thousands of orphaned wells remain unplugged, burdening taxpayers and local communities with environmental and economic risk.

In early 2024, I facilitated a pivotal EU-Canada dialogue workshop on methane emissions mitigation in Calgary, as part of the European Union Climate Dialogues (EUCDs) initiative. This session convened Canadian and European policymakers, industry leaders, and technical experts to address the pressing issue of methane emissions from the fossil fuel sector. Our discussions focused on harmonizing regulatory frameworks, advancing measurement technologies, and sharing best practices for emissions reduction in the industries’ operational wells and infrastructure, but didn’t deal with the legacy of abandoned wells, one that’s growing yearly.

Addressing this problem at scale is challenging. Plugging abandoned wells, an essential step to halt these leaks, is neither inexpensive nor uniform in cost. The expense per well ranges widely, from as low as $30,000 in straightforward, shallow scenarios in North America, to as high as $100,000 or more for deep, complex sites in places like offshore Europe or remote Siberian fields. At an average estimated cost of around $50,000 per well, the full price tag to plug all 4.5 million abandoned wells worldwide would approach $225 billion, potentially ballooning even higher depending on local complexities.

However, not every well leaks equally. A critical insight from the Lei study is the extreme skew in methane emissions distribution: roughly 10% of the unplugged wells are responsible for about 90% of total emissions. In practical terms, that means approximately 450,000 “super-emitting” wells dominate the global methane problem. Targeting these specific wells first could drastically improve both the economic viability and environmental effectiveness of plugging efforts.

Running the numbers clarifies the opportunity. Plugging only the highest-emitting 10%, the global “super-emitters,” could avoid emissions of approximately 9 million metric tons of methane over 25 years. At the 20-year GWP of methane, this equates to about 774 million metric tons of CO₂-equivalent. At a typical cost of $50,000 per well, addressing these 450,000 high-priority sites would require around $22.5 billion, translating to an exceptionally cost-effective abatement cost of roughly $29 per tonne of CO₂-equivalent avoided. By comparison, the universal approach, plugging all 4.5 million wells, yields a far higher average cost of $260 per tonne CO₂-equivalent, emphasizing the value of strategic, targeted intervention.

Geographical clustering plays a crucial role in the viability of these mitigation efforts. North America, particularly the United States and Canada, houses a disproportionately large share of the world’s abandoned wells, largely concentrated in historical oil and gas basins such as Alberta, Appalachia, and the Permian Basin. In Alberta alone, the provincial regulator acknowledges tens of thousands of orphaned wells, with remediation liabilities growing each year. Across the U.S., states like Texas, Pennsylvania, and Oklahoma face similar challenges, marked by historical neglect and regulatory gaps. Europe’s abandoned wells are fewer but more expensive to remediate due to stricter environmental standards and complexities of offshore infrastructure, while Russia, Middle Eastern countries, and Venezuela host massive, under-documented inventories.

The key to economically sensible and environmentally effective action, then, lies in intelligent prioritization backed by robust monitoring technology. Satellite and drone-based methane detection, aerial lidar surveys, and ground-based optical gas imaging provide a practical toolset for rapidly identifying the highest-emitting wells at scale. These methods not only ensure the effective allocation of limited resources but also establish verification frameworks that support public trust and private investment.

Who pays for this clean-up is another critical dimension. Historically, the fossil fuel industry has frequently escaped its environmental liabilities, externalizing costs onto taxpayers. Recent policy movements in North America, including orphan-well funds and methane fees introduced through Canada’s climate legislation and the increasingly threadbare U.S. Inflation Reduction Act, represent belated attempts to enforce a polluter-pays principle. Yet implementation remains patchy and politically contentious, leaving much remediation unfunded or delayed. Financing plugging initiatives through targeted carbon credits or green bonds tied directly to methane abatement performance could attract private capital, aligning market incentives with measurable environmental outcomes.

Beyond climate mitigation, plugging abandoned wells provides substantial co-benefits. Properly plugging wells protects local groundwater supplies, enables land reclamation, and reduces risks of hazardous gas exposure in nearby communities. Such projects can also assist local economies’ revenues, especially in regions historically reliant on declining oil and gas sectors, creating new jobs and expertise in environmental remediation and verification technologies.

Ultimately, the message from Lei et al.’s comprehensive global inventory and analysis is clear: the methane leaking from abandoned oil and gas wells represents an urgent but solvable climate risk. A targeted, data-driven approach focusing first on the highest-emitting wells globally can deliver significant and immediate climate benefits at an affordable cost. The faster governments and industry act, the greater the climate dividend, and the fewer resources required to stave off far more expensive interventions later.