Why Landfill Gas Capture Is the Fastest Lever the World Has Against Near-Term Warming

Every COP climate summit produces a fresh wave of headlines about carbon dioxide targets, net-zero dates, and energy transition pledges. Buried further down the agenda, but arguably far more urgent for the next two decades, sits a much quieter commitment: the Global Methane Pledge, launched at COP26 in Glasgow in 2021 and now backed by well over 150 countries and the European Commission. Its core aim is simple to state and hard to deliver — cut global methane emissions by at least 30% from 2020 levels by 2030.

That single target matters more than its modest media profile suggests, because methane behaves completely differently in the atmosphere to carbon dioxide, and one of the largest, most controllable sources of it is sitting under our feet in landfills.

A short-lived gas with an outsized punch

Carbon dioxide, once emitted, lingers in the atmosphere for centuries. Methane is the opposite kind of problem: it breaks down relatively quickly, with an atmospheric lifetime of roughly a decade, before it oxidises into CO2 and water vapour. That short lifespan is precisely why cutting methane now is one of the few climate actions capable of producing a measurable cooling effect within the lifetime of people alive today, rather than a benefit that only accrues to future generations.

This short atmospheric life is also the reason people encounter such wildly different figures when they read that methane is "many times worse than CO2." The commonly cited number of around 28–30 times more potent is based on the 100-year Global Warming Potential (GWP100), a metric that averages methane's warming effect over a century — a timescale chosen mainly because it lines up conveniently with CO2's long residence time, not because it reflects methane's own behaviour. Measured instead over a 20-year window (GWP20), which better represents the period during which methane is actually doing most of its warming work, the multiplier jumps to somewhere in the region of 80 or more. Neither figure is "wrong"; they are answering different questions. But the practical upshot for policy is this: because methane exerts most of its warming influence early and then fades, reducing methane emissions today delivers a disproportionately fast slowing of near-term warming compared with an equivalent tonne of CO2 reduced. It is often described, accurately, as the fastest brake available on the rate of global temperature rise this decade, even though it does nothing to address the much longer-run problem of accumulated CO2.

Where does this potent, short-lived gas mostly come from? The waste sector, and landfills specifically, is one of the three largest anthropogenic sources of methane worldwide, alongside fossil fuel operations and agriculture. Municipal solid waste buried in landfills decomposes anaerobically, generating landfill gas that is typically around half methane and half carbon dioxide. Left uncontrolled, that gas migrates upward and escapes into the atmosphere continuously for years, sometimes decades, after waste is placed.

Landfill gas extraction: proven, available, and profitable

Unlike many methane sources, landfill emissions can actually be dealt with using equipment and methods that already exist and have been proven to work for decades. Gas collection and control systems (GCCS) — networks of vertical wells or horizontal trenches connected to a header pipe system and a blower/flare or utilisation plant — have been installed at large landfills for decades. Captured gas can simply be flared (converting methane to the less potent CO2), or far better, utilised: cleaned and used to generate electricity, upgraded to pipeline-quality renewable natural gas, or used directly as a boiler fuel. Because the technology already exists and operators can earn money back by selling the captured gas as energy, this is widely seen as one of the cheapest and most effective ways available anywhere to cut methane emissions.

Recognising this, several bodies have set out targets for how much landfill gas the waste industry should be capturing and putting to use over the coming five to ten years. The US Environmental Protection Agency remains the most prominent of these, operating the long-standing Landfill Methane Outreach Program and, more recently, the Global Methane Initiative secretariat, both of which push operators toward earlier installation of gas collection infrastructure, lower capture thresholds for smaller sites, and higher utilisation rates rather than simple flaring. The Global Methane Pledge's own Waste Pathway, and initiatives such as Lowering Organic Waste Methane, have set sector-wide ambitions to deliver millions of tonnes of annual methane reductions from waste well before 2030, with landfill gas capture identified as one of the principal mechanisms for getting there.

The monitoring gap: you cannot manage what you cannot measure

Here is where the ambition starts to run ahead of the evidence base. Setting a capture-and-utilisation target is one thing; verifying whether it is actually being achieved at the thousands of individual landfills across the world is quite another. Most regulatory reporting still relies on model-based estimates — calculations built from waste tonnages, assumed decay rates, and the operational specification of the gas collection system — rather than direct, continuous measurement of what is actually reaching the atmosphere. Surface emissions monitoring at many sites is still periodic, patchy, or based on outdated assumptions about collection efficiency, meaning that regulators, investors, and the public are frequently working from figures that understate the true picture.

This is precisely the gap that satellite-based remote sensing of methane plumes is starting to close. Instruments such as the TROPOMI sensor aboard the Sentinel-5P satellite, combined with atmospheric transport modelling, and increasingly detailed commercial datasets from providers like Carbon Mapper, can now detect and quantify methane plumes rising from individual landfill sites from orbit. Crucially, this is a genuinely independent, top-down check on emissions, sitting alongside the ground-level, bottom-up work of assessing how efficiently a site's own gas collection system is actually performing. Bringing these two views together — engineering-level GCCS efficiency data from the ground, and plume-based methane detection from above — is what a truly comprehensive landfill monitoring regime looks like, and it is still the exception rather than the rule.

The consequences of not having that comprehensive monitoring in place are not hypothetical. Researchers at Harvard's School of Engineering and Applied Sciences combined 2019 TROPOMI satellite observations with atmospheric modelling and compared the results against official EPA inventory figures for the same year. The conclusion was stark: methane emissions from landfills were found to run around 50% higher than the EPA's own reported estimates, with the underestimate at some individual sites running considerably higher still. Follow-up analysis of major US urban areas found landfill under-reporting to be a key driver of even larger citywide discrepancies. In effect, the agency responsible for tracking and regulating one of the country's largest methane sources has effectively acknowledged that its historical data has been missing roughly half of the actual emissions from landfills — a gap attributed largely to gas collection systems performing less efficiently in practice than assumed, and to emissions occurring before collection infrastructure is installed or expanded.

Closing the gap between targets and reality

None of this undermines the case for landfill gas capture — if anything, it strengthens it considerably. If landfills are emitting substantially more methane than official figures suggest, then the climate benefit available from properly designed, well-monitored, promptly installed gas collection and utilisation systems is larger than currently credited, and the near-term temperature benefit of getting this right is significant given methane's short atmospheric life. What the EPA's own admission makes clear is that targets alone are not enough. The waste industry, regulators, and the wider climate community need routine, comparable, verifiable data on how effectively individual sites are actually capturing the gas they generate, checked against independent atmospheric observation rather than assumption-based modelling alone.

For those working operationally in this space — landfill operators, environmental consultants, and insurers assessing process risk at waste facilities — getting the practical basics of gas collection and flaring right is the foundation everything else is built on. A useful reference for that operational side of the picture is this set of landfill gas monitoring and flaring checklists, which sets out the kind of routine operational checks that underpin reliable gas collection system performance.

The Global Methane Pledge has put a number on the table and a deadline against it. Landfill gas capture is one of the few places where the engineering to hit that number already exists. What is missing, and what needs to catch up fastest, is the measurement infrastructure — on the ground and from orbit — capable of proving whether the world is actually closing the gap, or simply hoping it is.