Methane from rubbish: why landfills have become a climate target
Published on 2 October 2026 at 03:31 GMT
By Editorial Team SDG13
Food scraps discarded in a kitchen can continue affecting the climate long after the bin has been emptied. Buried with other rubbish, organic material decomposes without oxygen and releases landfill methane. Capturing that gas, or preventing its formation by diverting organic waste, connects an everyday municipal service with efforts to slow warming. The practical choices extend from household sorting to the financing and supervision of disposal sites.
Why buried food produces methane
Freshly deposited waste initially contains oxygen. As that oxygen is consumed, conditions favour microorganisms that break down organic matter anaerobically, producing methane and carbon dioxide. Food, garden waste and other biodegradable materials supply the feedstock. The US Environmental Protection Agency (EPA) describes landfill gas as roughly half methane and half carbon dioxide, with small quantities of other compounds. Generation rates vary with waste composition and conditions inside the landfill.
Methane remains in the atmosphere for roughly a decade, much less time than the long-lasting influence of carbon dioxide. Sustained cuts can therefore slow the rate of warming relatively quickly. That means less warming than would otherwise occur, rather than an immediate reversal of global temperature rise. Methane reductions complement carbon dioxide cuts; they do not replace them.
The 2021 Global Methane Assessment, published by the United Nations Environment Programme and the Climate and Clean Air Coalition, estimated that landfills and wastewater together accounted for about 20 per cent of human-caused methane emissions. That figure does not describe landfills alone. The assessment also links methane to ground-level ozone formation, explaining why reductions can benefit public health beyond the boundaries of a waste facility.
Gas capture has limits
At an engineered landfill, wells and pipes draw gas towards a collection system. Captured methane can be burned in a flare or treated for energy use, including electricity generation. Combustion converts methane primarily into carbon dioxide and water, reducing its warming impact compared with release as methane. Gas collection can also reduce odours and hazards associated with escaping landfill gas.
However, installing equipment is not equivalent to eliminating emissions. Collection depends on the area served, the condition of the cover and the operation of the wells. Some gas escapes before collection begins. A system producing electricity can therefore coexist with methane emissions from the same site.
Food waste makes that timing particularly consequential. In its 2023 modelling study covering US municipal solid waste landfills from 1990 to 2020, the EPA estimated that food waste accounted for about 58 per cent of methane escaping to the atmosphere in 2020. Food decomposes rapidly, potentially generating gas before collection systems are installed. This is a model-based US estimate, not a measured global proportion, but it illustrates why capturing gas and diverting fresh food waste address different parts of the problem.
Alternatives begin before disposal
Separate food-waste collection makes material available for treatment outside a landfill. Households, restaurants and markets separate organics from mixed rubbish; collection services then carry them to facilities able to process them. The outcome depends on what reaches those facilities. Plastic packaging and other contaminants can remain in separated waste, complicating processing and reducing the quality of products returned to land.
Composting uses oxygen to turn organic material into a soil amendment. Aeration and moisture management influence decomposition and emissions. Oxygen-starved zones within compost piles can generate methane, so composting is not emission-free. Finished compost can add organic matter and improve soil water retention, provided the input materials and treatment produce a suitable product.
Anaerobic digestion deliberately uses oxygen-free conditions inside a controlled system, collecting the resulting biogas for use. It also produces digestate, a nutrient-rich residue that can undergo further treatment or be used on land where appropriate. Its climate performance depends partly on gas containment and how the digestate is handled. Escaping methane erodes the benefit of recovering energy.
The EPA’s From Field to Bin assessment places food-waste prevention among the environmentally preferable options because avoiding surplus production also avoids upstream resource use. Composting and digestion recover value from discarded material, but cannot undo all the impacts of growing, processing and transporting food that was never eaten.
Unequal starting points for cities
In cities with established collection services, separate organics schemes involve bins, collection routes, treatment capacity and public participation. A separate container has limited effect if its contents ultimately enter mixed disposal. Assessing a scheme therefore involves tracking both the amount collected and its final destination, alongside contamination and treatment emissions.
Rapidly growing urban areas in lower-income countries often face a more basic service gap. The World Bank’s What a Waste 3.0, released in 2026, describes waste growth outpacing local capacity and budgets, particularly in sub-Saharan Africa and South Asia. It estimates global municipal waste generation at 2.56 billion tonnes in 2022 and projects 3.86 billion tonnes by 2050 under business as usual. The latter is a scenario, not an inevitable outcome.
Where rubbish is uncollected, openly dumped or burned, climate policy overlaps with immediate exposure to pollution and waste blocking drainage. Extending collection and controlled treatment involves sustained operating expenditure as well as construction. Informal waste workers also form part of existing collection and recovery systems, making their livelihoods relevant to service changes.
These differences raise questions of urban governance: who pays for collection, who operates treatment plants, and how are service coverage and emissions verified? Gas recovered for sale and tonnes diverted from landfill describe different outcomes. Neither figure alone establishes the full climate performance of a waste system.
The connection to SDG 13 (climate action) lies in reducing a powerful warming pollutant through waste management. Existing buried waste continues to generate emissions, while decisions about newly discarded food affect future methane production. The resulting climate benefit depends on the operation of collection and treatment services as well as the technology installed.
Written by a human author, edited with AI assistance.
Further information:
United Nations Environment Programme and Climate and Clean Air Coalition, Global Methane Assessment (2021), summary for decision makers. Explains methane’s atmospheric lifetime, waste-sector contribution and climate and health effects.
US Environmental Protection Agency, Basic information about landfill gas. Explains gas formation, collection systems, flaring and energy use.
US Environmental Protection Agency, Quantifying methane emissions from landfilled food waste (2023). Provides the model-based US estimate and explains the timing of food decomposition and gas capture.
US Environmental Protection Agency, From Field to Bin (2023). Examines food-waste treatment pathways, contamination, emissions and resource recovery.
Source: https://www.epa.gov/land-research/field-bin-environmental-impacts-us-food-waste-management-pathways
World Bank, What a Waste 3.0 (2026). Provides waste-generation estimates and projections, collection and financing context, and discussion of waste-sector employment.
.
