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Page 2 of 18 Shang et al. Carbon Footprints 2025, 4, 24 https://dx.doi.org/10.20517/cf.2025.28

INTRODUCTION
Methane is the second most significant greenhouse gas, with a 100-year global warming potential
(GWP100) of 27.9. Effectively controlling methane emissions is a critical component of global climate
governance, contributing not only to climate mitigation but also to economic co-benefits due to methane’s
inherent energy value. Annual global methane emissions are estimated at around 610 million tons, with
[1]
human activities accounting for nearly two-thirds of the total . Methane emissions have continued to rise,
reaching approximately 572-689 Tg per year during 2008-2017, reflecting a persistent upward trend since
[3]
[2]
the early 2000s , with anthropogenic sources contributing about half of the total budget . While global
methane emissions continue to grow, regional trajectories diverge significantly: emissions from Annex I
parties such as the EU, USA, and Russia have declined since 1990, whereas non-Annex I countries including
Brazil, China, India, Indonesia, and the Democratic Republic of the Congo have experienced substantial
[4-6]
increases . Current assessments emphasize the urgent need to achieve substantial methane reductions by
2030 to meet the objectives of the Paris Agreement. Achieving net-zero warming by 2050, relative to 2020,
could be possible through rapid technical and behavioral interventions, provided these measures are
implemented between 2033 and 2041 in line with the Global Methane Pledge .
[7]
The waste management sector represents a major source of anthropogenic methane, responsible for 19.9%
of global emissions in 2022 . Over the past five decades, globalization-driven economic expansion has led
[8]
to rising resource consumption in production and consumption systems, thereby intensifying methane
[1]
emissions from waste streams . Between 2010 and 2021, methane emissions from waste treatment grew
faster than those from agriculture (48.4%) and energy (31.7%), reaching 19.9% of total emissions, with an
[9]
average annual increase of 1.68% from solid waste treatment and wastewater management . Compared
with the energy sector, methane control technologies in waste management are generally more technically
mature, offer a broader range of mitigation approaches, and respond more readily to policy interventions.
Successful practices such as solid waste recycling and landfill gas recovery provide important empirical
references for effective emission reduction strategies. For example, since 1990, the United States has
implemented regulatory standards under the Resource Conservation and Recovery Act and the Clean Air
Act to cap urban landfill sites and prevent gas leakage, resulting in a sharp decline in methane emissions
from waste disposal between 1990 and 2000. In 1996, the UK introduced a landfill tax imposing high fees on
biodegradable waste, effectively reducing methane emissions. Similarly, in 1999, the European Union issued
the Landfill Directive, mandating the recovery and utilization of landfill gas or its combustion at landfill
[9]
sites. China has also prioritized non-CO greenhouse gas reduction . In 2023, the Ministry of Ecology and
2
Environment of China launched the Methane Emissions Control Plan, outlining measures and targets for
reducing methane emissions across energy, agriculture, livestock, waste management, and wastewater
treatment by 2030. However, projections by the United Nations Environment Programme (UNEP) under
baseline policy scenarios suggest continued growth in waste-related methane emissions, with a likely peak
around 2050 . This trajectory underscores the urgent need to accelerate technological implementation and
[10]
strengthen policy frameworks in waste management systems.

Research on methane emissions from waste systems has largely focused on municipal solid waste (MSW)
and wastewater treatment infrastructure. Many studies indicate that methane emissions from these sectors
are underestimated globally [11-14] . Du et al. analyzed provincial-level methane emissions from MSW landfills
in China using IPCC Guidelines for National Greenhouse Gas Inventories and first-order decay modeling,
revealing an annual increase of 71.79 Gg between 2003 and 2013, with faster growth in northern and
western provinces compared with coastal regions . Ghosh et al. assessed methane emissions from three
[15]
non-engineered landfills in Delhi (1984-2015) using the IPCC Default Method (DM), First-Order Decay
(FOD), and Landfill Gas Emissions Model (LandGEM) . They reported estimated emissions of
[16]