Landfill Methane Could Push Iran’s Waste Emissions to 21 Million Tonnes by 2040, Study Finds

A new country-level study of Iran’s municipal solid waste system projects that greenhouse gas emissions from the sector could range from roughly 1.4 to 21 million tonnes of CO2 equivalent per year by 2040, depending entirely on which waste management pathway the country pursues. The research, published in Clean Technologies and Environmental Policy by Maryam Abbasi and Seyyed Mostafa Mehrdad of Shahid Beheshti University in Tehran, is among the first to combine long-term national forecasting with province-scale resolution for a major developing economy’s waste sector.

The study addresses a persistent blind spot in climate accounting. While many countries have detailed inventories for energy, transport, and industry, the waste sector in developing economies is often assessed only through fragmented local studies. Rapid population growth, accelerating urbanization, and industrial expansion have driven municipal solid waste generation sharply upward in such countries, and the waste stream itself is typically rich in organic material. When that organic fraction decomposes in landfills under anaerobic conditions, methanogenic bacteria convert it into methane, a greenhouse gas with a global warming potential far exceeding that of carbon dioxide over a century-long horizon. Under landfill-dominant disposal systems, the authors note, this methane formation becomes the single largest driver of the sector’s climate footprint.

To capture how policy choices ripple through decades of waste infrastructure, the researchers constructed four alternative scenarios spanning 2020 to 2040. The baseline scenario assumes continuation of current practice, with landfill disposal remaining the dominant route for municipal waste. The alternatives progressively layer in the interventions that dominate modern waste policy debates: landfill gas recovery systems that capture methane before it escapes, expanded recycling and composting programs that divert biodegradable material away from disposal altogether, and controlled waste-to-energy implementation that burns residual waste under regulated conditions while generating electricity. Each scenario was evaluated not only for its emissions trajectory but also for its economic and environmental implications, allowing the authors to weigh mitigation against cost.

The technical backbone of the analysis draws on internationally standardized estimation methods, including the 2006 IPCC guidelines for national greenhouse gas inventories and the supplementary guidance developed under the Kyoto Protocol. Methane generation from landfills depends on the quantity and composition of deposited waste, the moisture conditions within the landfill, and the decay rate of the organic fraction, all of which the model tracks over time. Emissions are expressed in tonnes of CO2 equivalent, the common currency of climate accounting that converts methane, nitrous oxide, and other gases into the amount of carbon dioxide that would produce the same warming effect. The authors also incorporated national statistics, including data from Iran’s Statistical Yearbook, alongside population projections to drive waste generation estimates across the study period.

The headline finding is the sheer spread of possible futures. Under the baseline, in which landfill disposal continues unchallenged, annual emissions from the waste sector climb toward the upper end of the range, roughly 21 million tonnes of CO2 equivalent per year, because uncontrolled methane generation from decomposing organic waste continues unchecked. At the opposite extreme, the integrated mitigation scenario, labeled S4 in the study, delivers the greatest reduction of any pathway, cutting approximately 1.8 million tonnes of CO2 equivalent relative to the alternatives. S4 achieves this by combining diversion of biodegradable waste away from landfills with improved recycling, expanded composting, and energy recovery systems, effectively attacking methane formation at its source while extracting value from the residual stream.

Perhaps the most consequential result, however, lies beneath the national totals. When the researchers disaggregated their projections to the provincial scale, they found that mitigation effectiveness varies substantially across Iran’s territory. Provinces with high waste generation achieve the largest absolute reductions under the intervention scenarios, simply because there is more material available to divert, capture, or convert. This spatial heterogeneity carries a direct policy implication: a uniform national strategy would leave significant reductions unrealized in some regions while over-investing in others. The authors argue that region-specific implementation, calibrated to local waste volumes, composition, and infrastructure, is essential for maximizing the climate return on mitigation spending.

The findings sit within a growing international literature on waste-sector climate mitigation. Comparable scenario studies have been conducted for Attica in Greece, for South Korea, for Chinese cities, and for Turkish landfill systems, each confirming that the choice between disposal and diversion dominates the sector’s emissions trajectory. Research on Chinese cities has documented decreasing greenhouse gas emissions from the municipal solid waste sector where diversion policies took hold, while assessments of Thai waste-to-energy facilities and São Paulo’s energy recovery potential illustrate how middle-income economies have monetized waste as a fuel. The Iranian study extends this evidence base by pairing national-scale forecasting with provincial granularity, a combination the authors identify as a clear gap in the existing literature.

The economic dimension of the analysis matters as much as the environmental one. Landfill gas recovery, composting, and waste-to-energy are not merely emission controls; they are revenue-generating infrastructure. Captured landfill gas can fuel electricity generation, compost displaces synthetic fertilizer demand, and energy-from-waste plants feed power grids. Studies cited in the paper, including assessments of landfill gas electricity generation in Korea using the Long-range Energy Alternative Planning model and comparative reviews of electricity generation potential across waste management technologies, underscore that the most effective climate strategies for the waste sector are frequently those that also produce marketable outputs. The Iranian results reinforce this pattern, with the integrated scenario delivering both the deepest emission cuts and enhanced energy recovery potential.

For Iran specifically, the stakes are amplified by the country’s broader climate commitments and its exposure to the impacts of a warming region. The waste sector represents one of the more tractable emission sources, since the underlying chemistry of methane formation is well understood and the intervention technologies are mature and widely deployed elsewhere. What the study demonstrates is that the difference between a passive future and an active one is enormous: a factor of roughly fifteen separates the high-emission baseline from the low-emission integrated pathway. Closing that gap requires diverting biodegradable waste from landfills at scale, building out composting and recycling capacity, deploying landfill gas capture, and introducing controlled waste-to-energy where appropriate, all tailored to the waste profile of each province.

The study’s provincial results offer a roadmap for that tailoring. High-waste provinces, which contribute the largest absolute emission reductions under the integrated scenario, are natural candidates for early infrastructure investment, while regions with smaller waste streams may achieve better returns through targeted composting and recycling programs rather than capital-intensive energy facilities. As developing economies worldwide grapple with rising waste volumes and tightening climate targets, the Iranian case study provides a quantified template: the emissions trajectory of a nation’s waste sector is not an inevitability of growth, but a direct consequence of the management choices made today.

Subject of Research: Forecasting greenhouse gas emissions from municipal solid waste management in Iran under alternative scenarios from 2020 to 2040

Article Title: Forecasting greenhouse gas emissions from municipal waste management under alternative scenarios: a country-level study

Article References: Abbasi, M., & Mehrdad, S. M. (2026). Forecasting greenhouse gas emissions from municipal waste management under alternative scenarios: a country-level study. Clean Technologies and Environmental Policy, 28(11), Article 274. https://doi.org/10.1007/s10098-026-03571-z

Image Credits: AI Generated

DOI: 10.1007/s10098-026-03571-z

Keywords: greenhouse gas emissions, municipal solid waste, methane, landfill gas recovery, waste-to-energy, composting, recycling, Iran, climate mitigation, scenario analysis, CO2 equivalent, waste management