By Olivia Rosane and Cristen Hemingway Jaynes
Methane, a powerful greenhouse gas that is colourless, odourless, and found everywhere from wetlands and cattle to household heating furnaces, has emerged as one of the most critical frontiers in the global response to the climate crisis. Ranking second only to carbon dioxide as a driver of planetary warming, methane is the primary component of natural gas, which currently accounts for roughly 25 percent of the world’s electricity generation.
Composed of four hydrogen atoms bonded to a carbon atom, this hydrocarbon is abundant in nature and forms through both geological and biological processes. Geologically, it is created when heat and pressure act on decomposing organic matter over millions of years, forming the foundation of conventional natural gas reserves, though it can also form deep underground without organic precursors. Biologically, methane is produced through a process called methanogenesis, wherein specialized underwater microorganisms known as archaea generate the gas during oxygen-free respiration. This biological pathway accounts for natural emissions above ground, including those emerging from wetlands and the digestive tracts of animals such as termites and cattle.
How Is Methane Measured?
Scientists and engineers measure atmospheric methane primarily through two complementary frameworks: bottom-up and top-down approaches. Bottom-up methodologies begin at the localized source on the ground and scale outward. These assessments rely either on direct facility measurements or mathematical estimations derived from general knowledge about emitting equipment and livestock. For instance, researchers calculating the agricultural footprint of a country’s dairy sector might multiply an average emission rate per animal by the total cow population, applying a similar formula to regional oil drilling operations and natural gas infrastructure.
Conversely, top-down approaches begin in the atmosphere, utilizing aircraft, high-altitude observation platforms, and an increasingly sophisticated fleet of satellites. When combined with atmospheric modeling and inventories of known methane sources and sinks, these aerial observations provide a comprehensive regional and global picture.
As satellite technology advances, it is increasingly capable of detecting extraordinary super-emitting incidents that traditional bottom-up inventories routinely overlook. For example, when a fossil fuel operator calculates leaks by multiplying a standard equipment failure rate by the total number of units in service, it misses the catastrophic leaks that disproportionately drive emissions. Scientific studies indicate that the largest five percent of gas-industry leaks typically account for more than half of all leakage volume. Overall, direct measurements from the ground and sky demonstrate that real-world emissions frequently dwarf official estimates. One prominent study revealed that direct measurements of U.S. oil and gas emissions were 60 percent higher than figures reported by the U.S. Environmental Protection Agency. Improving these measurement techniques remains essential for developing effective control strategies.
How Does Methane Contribute to the Climate Crisis?
Once released into the atmosphere, methane acts as a potent greenhouse gas, absorbing heat energy radiated from the Earth’s surface and redirecting it back toward the planet. Natural sinks, primarily located in soils and the troposphere where the gas breaks down into carbon dioxide and water vapor, historically maintained a stable equilibrium with natural emissions. However, human activities since the dawn of the industrial revolution—particularly fossil fuel extraction, intensive agriculture, and expanded waste storage—have injected methane into the atmosphere at a rate far exceeding the capacity of natural sinks to absorb it.
By 2023, the most recent year with complete data available, atmospheric methane concentrations had surged by 265 percent compared to pre-industrial levels, reaching 1,934 parts per billion. Human activities account for approximately 60 percent of current emissions, which have driven roughly one-third of total global heating to date. Projections indicate that without targeted mitigation, baseline emissions could rise another 13 percent between 2020 and 2030.
Controlling methane is uniquely urgent 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 an equivalent mass of carbon dioxide, a figure that drops to 28 times over a century. This high potency combined with a short lifespan means that curbing methane offers an immediate opportunity to stabilize global temperatures. The Global Methane Assessment concluded that aggressive mitigation is the single most effective strategy to slow warming over the next two decades. Similarly, the Intergovernmental Panel on Climate Change (IPCC) has calculated that global methane emissions must fall by approximately 34 percent below 2019 levels by 2030 to keep global heating within the critical threshold of 1.5 degrees Celsius.
What Are the Main Sources of Methane?
Human activities account for roughly 60 percent of atmospheric methane, while natural sources make up the remaining 40 percent. More than 90 percent of anthropogenic emissions stem from three primary sectors: agriculture, fossil fuels, and waste storage, while biomass burning and biofuels contribute a minor five percent. Wetlands and freshwater bodies represent the largest natural sources, followed by geological seeps, volcanoes, wild animals, oceans, and thawing permafrost.
Agriculture is responsible for about 40 percent of human-caused methane emissions, driven primarily by livestock. Ruminant animals such as cattle, sheep, and goats produce methane as a byproduct of enteric fermentation, a digestive process where microbes break down fibrous plant material. Cattle raised for beef and dairy are the largest agricultural contributors. Manure storage from concentrated animal feeding operations further compounds these emissions, which are projected to increase as global meat consumption rises.
Rice cultivation represents the second largest agricultural source, accounting for eight percent of human-caused emissions. Flooded rice paddies create ideal waterlogged environments for anaerobic, methane-producing microbes. Fossil fuel operations contribute another 35 percent of anthropogenic emissions, split between oil and gas supply chains and coal mining. Venting and fugitive leaks during the extraction, processing, and transport of oil and natural gas account for 23 percent of human-caused emissions. Coal mining operations release the remaining 12 percent, with underground mines producing the vast majority of these emissions through ventilation and drainage systems.
Landfills and waste management systems generate approximately 20 percent of human-caused emissions as microbes decompose organic waste in landfills and wastewater treatment facilities. Due to global population growth and urbanization in developing economies, waste-related emissions are projected to grow faster than any other category over the coming decades.
Natural sources are dominated by wetlands, which cover roughly six percent of the Earth’s land area and produce about one-third of all global methane. The climate crisis has accelerated natural wetland emissions through temperature increases and altered precipitation patterns, creating a feedback loop known as the wetland methane feedback. Tropical wetlands and thawing Arctic permafrost have driven significant surges in natural emissions in recent years. Oceans contribute a smaller share through geological seeps, coastal groundwater inputs, and marine sediments, while positive feedback loops involving thawing permafrost and intensifying wildfires threaten to release vast reserves of ancient carbon into the atmosphere.
Methane and the ‘Bridge Fuel’ Myth
Future emissions trajectory remains closely tied to the expansion of fossil gas production and liquefied natural gas (LNG) infrastructure. Following the proliferation of hydraulic fracturing in North America, the United States became the world’s leading natural gas exporter by 2022. Proponents of the industry have long positioned natural gas as a necessary "bridge fuel" from coal to renewables, citing the fact that burning coal emits twice as much carbon dioxide per kilowatt-hour as natural gas.
However, this argument often discounts the extensive leakage of methane throughout the extraction and supply chain. Studies indicate that if leakage rates exceed a fraction of a percent, the climate warming potential of natural gas matches or exceeds that of coal over a 20-year timeframe. Furthermore, government analyses have suggested that expanded LNG exports frequently displace renewable energy investments rather than coal. Analysts warn that planned fossil fuel expansion projects risk locking in emissions levels that could overwhelm global climate stabilization efforts.
What Are Other Benefits to Reducing Methane Emissions?
Beyond its direct impact on global temperatures, atmospheric methane reacts with other compounds to form ground-level ozone, a dangerous pollutant that damages human lung tissue and agricultural crops. Tropospheric ozone currently contributes to half a million premature deaths annually. Research indicates that every million metric tons of avoided methane emissions prevents thousands of deaths and asthma-related medical emergencies while protecting vital crop yields for wheat, soybeans, maize, and rice.
What Can Be Done to Reduce Methane Emissions?
Mitigating methane requires a combination of systemic transformations and technical fixes across agriculture, energy, and waste management. Current technologies and dietary shifts could achieve a 45 percent reduction in human-caused methane emissions by 2030, aligning with the IPCC pathways for limiting warming to 1.5 degrees Celsius.
In agriculture, strategies include shifting toward plant-based diets, reducing food waste, and improving livestock feeding practices. The addition of enteric methane inhibitors, such as specific seaweed supplements or chemical additives like 3-NOP, has been shown to reduce ruminant emissions significantly without harming animal health. Rice cultivation emissions can be curtailed through improved water management practices, such as intermittent drying of paddies, and the adoption of lower-methane crop varieties.
Within the fossil fuel sector, the most impactful short-term measure involves rigorous leak detection and repair programs across existing oil and gas infrastructure, alongside the phasing out of routine venting and flaring. International energy agencies note that a significant portion of oil and gas sector emissions can be abated at zero net cost using currently available technology. For waste management, expanding organic waste diversion, upgrading wastewater treatment plants to capture biogas, and implementing zero-waste circular economy policies offer immediate emissions reductions.
What Progress Has Been Made to Reduce Methane Emissions So Far?
At the COP26 climate summit in Glasgow, the United States and the United Kingdom launched the Global Methane Pledge, which has since expanded to include 159 participating nations committed to cutting global methane emissions by 30 percent below 2020 levels by the end of the decade. Despite these diplomatic commitments, global emissions have continued to rise, breaking new records in recent years. Observers point to a persistent implementation gap, with only a small fraction of global methane emissions currently covered by binding regulatory policies.
As policymakers, industry leaders, and communities grapple with the dual threat and opportunity presented by methane, accelerating mitigation efforts remains essential to preventing catastrophic climate tipping points while delivering immediate improvements to global air quality and public health.
