Methane
The overlooked greenhouse gas that is warming the planet roughly 80 times faster than CO2 in the near term — and whose sources are lying about how much they emit.
The short version
- Methane (CH4) is the second most significant human-driven greenhouse gas after CO2, warming the planet approximately 80 times more potently per molecule over a 20-year window — the timeframe that matters most for near-term tipping points.
- The three largest human sources are fossil fuel operations (leaks from wells, pipelines, and coal mines), livestock agriculture (primarily cattle through enteric fermentation), and landfills — each contributing roughly 30–40% of human methane emissions.
- Satellite data consistently shows actual methane emissions from oil and gas operations to be roughly 60% higher than industry self-reports to the EPA — adding the equivalent of tens of millions of cars to the atmosphere annually.
- Methane's 12-year atmospheric lifespan means that cutting emissions now produces measurable cooling within a decade — the fastest available lever for slowing near-term warming, faster than equivalent CO2 reductions.
What it is
Methane (CH4) is a colorless, odorless gas and the primary component of natural gas. It is also the second most significant greenhouse gas driving human-caused climate change after carbon dioxide. The two gases behave very differently in the atmosphere: CO2 persists for centuries to millennia once emitted, making it the dominant long-term warming driver; methane breaks down in roughly 12 years, but while present it traps heat far more intensively. Over a 20-year timeframe, methane warms the planet approximately 80 times more per unit mass than CO2. Over the standard 100-year comparison period used in most climate policy and IPCC assessments, that figure drops to roughly 30 times — a mathematically accurate but policy-distorting choice, because the 100-year window obscures methane's acute near-term potency during the critical decade when limiting warming below 1.5°C is still theoretically possible.
Methane enters the atmosphere from both natural and human sources. The largest natural source is wetlands, where decomposing organic matter produces methane in anaerobic conditions. Human sources are large, diverse, and in several cases dramatically under-counted. The three primary categories are fossil fuel operations (leaks from oil wells, natural gas pipelines, compressor stations, storage facilities, and coal mines), livestock agriculture (primarily enteric fermentation — the digestive process of ruminant animals, especially cattle, that produces methane as a byproduct — and manure management), and waste management (decomposing organic matter in landfills producing methane as it breaks down anaerobically). Fossil fuel operations contribute roughly 35–40% of human methane emissions globally; agriculture roughly 40%; waste roughly 20%, with rice cultivation in flooded paddies adding a smaller but meaningful share.
The data quality problem is acute. Unlike CO2 emissions, which can be estimated reasonably well from fuel combustion data, methane leaks are diffuse, numerous, often accidental, and difficult to inventory accurately from the ground. The U.S. oil and gas industry self-reports its methane emissions to the EPA through a reporting system that relies substantially on engineering estimates and industry-supplied data rather than direct measurement. A 2018 study published in Science, using aircraft measurements across major U.S. production regions, found that total oil and gas supply chain emissions were approximately 60% higher than EPA inventory estimates — an additional 13 million metric tons per year. Separate satellite analyses have documented large point-source emissions from individual facilities in Russia, Central Asia, and the Middle East that are absent from official national inventories entirely. The gap between reported and actual emissions is not a rounding error; it is climatically significant.
Methane concentrations in the atmosphere have been rising with a pattern that has alarmed climate scientists. Atmospheric methane grew slowly through the early 2000s, leading some researchers to speculate emissions had stabilized. Then growth resumed rapidly after 2006 and has accelerated since — a trajectory that climate models had not predicted and whose causes remain partially contested. Isotopic analysis suggests the recent surge is primarily biogenic (biological sources, likely tropical agriculture and wetlands) rather than thermogenic (fossil fuels), but fossil fuel contributions remain substantial. Of particular concern is the potential for Arctic permafrost thaw to release large stores of previously frozen organic matter as methane — a positive feedback loop in which warming drives methane release, which drives further warming. This Arctic amplification is considered one of the most significant near-term tipping point risks in the climate system.
Why it matters
Methane's short atmospheric lifespan makes it the fastest available lever for slowing near-term warming — a property with enormous practical significance given that the 1.5°C threshold the Paris Agreement targets is most at risk in the coming two decades. Studies have estimated that bringing global methane emissions to technically feasible minimums from fossil fuel operations alone — fixing leaks that can be detected and repaired with existing technology — would provide climate benefits equivalent to removing hundreds of millions of cars from the road within this decade. This is not a distant or speculative benefit; it operates on the same timescale as the political cycles in which climate decisions are being made. The Global Methane Pledge, signed by more than 100 countries at COP26 in Glasgow in 2021, commits signatories to reducing collective methane emissions 30% by 2030. Voluntary commitments have historically underperformed; whether this one proves different remains to be seen.
The natural gas industry's climate case depends entirely on methane leak rates that the industry cannot demonstrate it achieves. Natural gas burns more cleanly than coal when combusted — producing roughly half the CO2 per unit of electricity. This arithmetic is the foundation of the 'bridge fuel' argument: natural gas as a transitional energy source that reduces emissions while renewable capacity is built. But the bridge fuel case collapses if methane leakage from the supply chain exceeds approximately 2–3% of total production, at which point natural gas has a climate profile equivalent to coal over a 20-year window. Independent research using direct measurement rather than industry self-reports has found leak rates in major U.S. producing regions that regularly approach or exceed this threshold. The bridge fuel argument is structurally dependent on a leak rate the industry's own self-reported data has been shown to significantly understate.
Cattle and the food system present the other side of the methane problem — one that is biologically diffuse, politically sensitive, and resistant to simple regulatory solutions. The digestive processes of approximately 1 billion cattle worldwide produce roughly 14.5% of total global greenhouse gas emissions, according to the FAO — a larger share than the entire transportation sector. Producing one kilogram of beef protein generates approximately 300 times the greenhouse gas emissions of one kilogram of legume protein. Feed additives including 3-nitrooxypropanol (3-NOP) and certain seaweed compounds have shown 20–30% reductions in cattle methane in trials, but adoption remains voluntary and limited. Dietary shifts toward less ruminant meat are among the highest-impact individual actions available for reducing methane, but dietary policy is politically toxic in a way that pipeline leak regulations are not.
Regulatory history on methane has been a decade of instability. The EPA finalized methane regulations for oil and gas operations under the Obama administration in 2016 — requiring leak detection, repair programs, and controls on venting. The Trump administration rolled back those rules in 2020. The Biden administration reinstated and strengthened them in 2022. The Inflation Reduction Act (2022) included the first federal methane fee — $900 per metric ton of methane above threshold levels for large oil and gas facilities, rising to $1,500 — which created a financial incentive structure rather than relying solely on regulatory compliance. The fee's implementation has been delayed by legal challenge. The underlying dynamic — one administration builds a regulatory structure, the next dismantles it — reflects the same political instability that has plagued U.S. climate policy more broadly, and it is particularly damaging for methane governance because consistent monitoring and enforcement over time is what the problem requires.