By Olivia Rosane and Cristen Hemingway Jaynes
What has no color or smell and can be found drifting above wetlands, rising from cattle feedlots, or fueling your basement furnace? The answer is methane—a powerful greenhouse gas that stands as the second most important contributor to the global climate crisis, trailing only carbon dioxide. Beyond its role in atmospheric warming, methane serves as the primary component of natural gas, a fossil fuel that currently generates approximately 25 percent of the world’s electricity.
As a hydrocarbon composed of four hydrogen atoms bonded to a single carbon atom, methane is abundantly generated in nature through both geological and biological processes. Geologically, it forms when heat and pressure are applied to decomposing plant and animal matter over millions of years, creating the natural gas reservoirs extracted today. It can also form deep underground without organic matter. Biologically, methane is produced through methanogenesis, a process where underwater microorganisms known as archaea generate the gas in oxygen-free environments. This biological pathway accounts for methane emissions above ground in natural wetlands and inside the digestive tracts of animals like termites and cows.
How Is Methane Measured?
Scientists and engineers measure atmospheric methane primarily through two complementary methods: bottom-up and top-down approaches. Bottom-up assessments begin on the ground with localized sources and expand outward, relying either on direct facility measurements or mathematical estimations based on the behavior of emitting equipment and livestock. For instance, researchers might calculate a region’s agricultural emissions by multiplying the average output per animal by the total livestock population, or estimate industrial output using equipment leak rates.
Top-down approaches, by contrast, begin in the sky by measuring atmospheric concentrations using airplanes, high-altitude platforms, and increasingly sophisticated satellites. When combined with atmospheric modeling, these aerial observations provide a comprehensive picture of global emissions.
Advanced satellite technology has proven particularly crucial in identifying "super-emitting" incidents that traditional bottom-up inventories routinely miss. For example, if a gas facility estimates its leaks using standard equipment averages, it will fail to account for the catastrophic leaks that disproportionately drive industrial emissions. Research indicates that direct ground and air measurements of U.S. oil and gas operations are often 60 percent higher than estimates compiled by the U.S. Environmental Protection Agency. Refining these measurements remains essential for understanding and ultimately controlling atmospheric methane.
How Does Methane Contribute to the Climate Crisis?
Once released into the atmosphere, methane acts as a greenhouse gas by absorbing heat energy emitted from the Earth’s surface and redirecting it back toward the ground. While natural sinks—such as soil and chemical reactions in the troposphere—normally break methane down into carbon dioxide and water vapor, human activities since the industrial revolution have accelerated emissions far beyond the capacity of natural systems to absorb them.
Data from the World Meteorological Organization indicates that atmospheric methane concentrations surged to 1,934 parts per billion, marking a 265 percent increase over pre-industrial levels. Human activities drive roughly 60 percent of these emissions, fueling about one-third of current global heating. Without concerted reduction efforts, global methane emissions are projected to rise another 13 percent between 2020 and 2030.
Addressing methane is critical because the gas is far more potent than carbon dioxide, even though it has a much shorter atmospheric lifespan of roughly 12 years compared to centuries for carbon dioxide. Over a 20-year timespan, a unit of methane traps 86 times more heat than carbon dioxide. This high potency combined with its short lifespan means that curbing methane offers the single greatest potential to rapidly slow global warming over the next two decades, a strategy the Intergovernmental Panel on Climate Change says must reduce emissions by 34 percent by 2030 to keep global heating within 1.5 degrees Celsius.
What Are the Main Sources of Methane?
Human-caused activities generate approximately 60 percent of atmospheric methane, while natural sources account for the remaining 40 percent. More than 90 percent of anthropogenic emissions stem from three primary sectors: agriculture, fossil fuels, and waste storage.
Agricultural activities drive roughly 40 percent of human-caused emissions, with livestock representing the vast majority through enteric fermentation—the digestive process of ruminant animals like cows, sheep, and goats. Microbes in their digestive tracts break down nutrients and release methane as a byproduct. Manure storage and rice cultivation in flooded paddies, which encourage microbial growth, account for the remainder of agricultural emissions.
Fossil fuel operations contribute approximately 35 percent of human-caused methane. The extraction, transport, and use of oil and natural gas account for 23 percent, driven by intentional venting and accidental leaks. Coal mining operations and abandoned mines account for another 12 percent, as methane trapped along coal seams escapes during extraction and ventilation. Furthermore, researchers utilizing satellite imaging have identified hundreds of massive super-emitter events at fossil fuel sites globally, where single leaks can match the hourly emissions of entire industrialized nations.
Landfills and waste management systems account for roughly 20 percent of human-caused emissions, as microbes decompose organic waste in wastewater facilities and disposal sites. With urban populations growing, waste-related emissions are projected to rise faster than any other category in the coming decades.
Natural emissions are dominated by wetlands, which cover roughly six percent of the Earth’s land area and account for about one-third of total global methane emissions. Water-saturated, oxygen-poor wetland soils provide ideal conditions for methane-producing microbes. Climate change has exacerbated these natural emissions through positive feedback loops, as warming temperatures and shifting rainfall patterns accelerate microbial activity in tropical and permafrost wetlands alike. Oceans, geological seeps, and wildfires also contribute minor shares to the global methane budget.
Methane and the ‘Bridge Fuel’ Myth
The ongoing expansion of natural gas production and liquefied natural gas exports has raised serious concerns among climate scientists. Proponents of natural gas have long promoted it as a "bridge fuel" from coal to renewables, noting that burning natural gas emits half the carbon dioxide of coal per kilowatt-hour.
However, this argument often ignores the massive volume of methane that leaks during the extraction, liquefaction, and transport of natural gas. Studies demonstrate that if even a fraction of gas escapes unburned during its lifecycle, its warming impact quickly surpasses that of coal. Advanced satellite data indicates that leakage rates have been significantly underestimated, rendering liquefied natural gas substantially more damaging to the climate over a 20-year horizon than previously acknowledged. Major fossil fuel infrastructure expansions threaten to lock in high emissions levels that could easily overwhelm global decarbonization efforts.
What Are Other Benefits to Reducing Methane Emissions?
Curbing methane yields immediate benefits beyond stabilizing the climate. Methane reacts in the lower atmosphere to form ground-level ozone, a hazardous air pollutant that damages human lung tissue and agricultural crops. Methane-induced ozone currently contributes to roughly half a million premature deaths annually. Experts calculate that every million metric tons of methane avoided prevents thousands of heart and respiratory disease deaths, asthma-related emergency room visits, and massive agricultural crop losses worldwide.
What Can Be Done to Reduce Methane Emissions?
A combination of large-scale systemic transformations and targeted technical fixes can curb human-caused methane emissions by 45 percent by 2030, aligning with global climate targets. In agriculture, solutions include dietary shifts away from excessive meat consumption, improved livestock feed efficiency, seaweed feed additives that inhibit gut fermentation, and the capture of biogas from manure storage.
In the energy sector, phasing out fossil fuels remains the ultimate goal, but immediate operational fixes—such as enhanced leak detection and repair, the replacement of venting equipment, and the installation of degasification wells at coal mines—can slash oil and gas emissions significantly using existing technology. Waste-related emissions can be mitigated through zero-waste initiatives, composting organic matter, and upgrading wastewater treatment facilities to capture biogas.
While international frameworks like the Global Methane Pledge aim to cut global emissions by 30 percent by 2030 across nearly 160 nations, real-world emissions continue to break records due to implementation gaps and limited regulatory enforcement. Individual actions, such as reducing food waste, adopting plant-forward diets, and transitioning home appliances away from fossil gas, can complement broader political and industrial reforms necessary to rein in the planet’s most responsive greenhouse gas.
