Japan's Sources of CH4 Emissions
Key Insights
Methane’s Role In Japan
Methane from human activities in Japan accounts for around 4% of the country's overall warming impact. The largest sources are crop production (about a third), waste (roughly a quarter), and both livestock and fugitive emissions (each near a fifth), with fuel combustion contributing a smaller share. The balance has shifted notably over time.
Post-War Surge, Then Reversal
Through the post-war era, emissions rose quickly. Fugitive emissions accelerated, reaching around 30 megatonnes by about 1970, while waste rose toward 20 through the 1970s-1980s. Crop production also climbed into the early 1960s, peaking near 20. This period marked the high point for several major sources before long declines set in.
Sustained Declines Since 1990s
From the 1970s onward-and more clearly since the 1990s-most sectors have fallen. Fugitive emissions dropped from around 30 to just over 3 today. Waste declined from roughly 20 to around 6. Crop production fell from about 20 in the early 1960s to under 10 now, and livestock edged down from around 9 in the late 1980s to roughly 7. Fuel combustion has eased slightly since the late 1990s, remaining near 2-3.
Current Trajectory And Priorities
Japan's dominant methane sources are generally declining. The fastest drops are in fugitive emissions and waste, with steadier, slower reductions in crop production and livestock; fuel combustion is small and trending down. Keeping this momentum while accelerating cuts in the biggest contributors-especially crop production and waste-would deliver the most near-term gains.
Background
The chart shows a national breakdown by source of the yearly methane (CH4) emissions from human activities expressed as weight in megatonnes (Mt). In the scientific literature, these are referred to as anthropogenic emissions. Human-induced methane emissions increase atmospheric methane, which is warming the Earth. The sources of human methane emissions are
- Livestock
- Fugitive emissions from the fossil fuel industry
- Crop production
- Fossil fuel combustion
- Waste management
- Other processes
Methane's Global Warming Potential
Methane has a much higher Global Warming Potential (GWP) than CO2. However, the effect lasts only for a relatively brief period (9 years on average), compared to hundreds of years for CO2. A reduction in emissions can cause a rapid decline in its atmospheric levels and climate impact.
Livestock
Livestock emits methane that is produced in the animals' digestive system. Most methane is emitted from the mouth during rumination. A much smaller amount of methane is emitted from the manure. Depending on how the manure is managed, i.e., wet or dry, more methane is emitted. Wet management leads to higher methane emissions than dry management. However, dry management also emits nitrous oxide (N2O), which is another potent greenhouse gas.
Fugitive emissions from fossil fuel industry
Fugitive methane emissions are from the intentional and accidental release of methane, which happens during the extraction, storage, and transportation processes in the fossil fuel industry. Examples are methane leaks during oil and gas handling, storage, transport, incomplete combustion, and many more. Also, methane is deliberately ventilated from mines during the extraction of coal.
Methane is a primary part of “gas”, also called “natural gas” or “fossil gas”. Natural gas is used, for example, for heating and electricity generation, whereby it emits CO2 during the combustion process. However, when natural gas leaks (unburned) it contains a lot of fugitive methane emissions.
Waste
Waste from landfills and wastewater produces a lot of methane when biodegradable material breaks down without oxygen.
Crop production
Crop production emissions are largely from rice cultivation, which generates large amounts of methane during plant growth. These emissions are from flooded paddies, which create the swamp-like environment of rice fields. There are agricultural techniques to reduce emissions significantly, like periodic drainage and aeration. Rice is the main staple for about half the world's population, and its emissions are a significant part of total human methane emissions.
Fuel combustion
Fuel combustion emissions are mostly from the incomplete combustion of fossil fuels. As mentioned before, natural gas consists largely of methane, and when the combustion does not happen completely, methane enters the atmosphere.
Other
Other human-induced methane emissions include industrial processes and product uses.
Wikipedia: Anthropogenic Sources of Atmospheric MethaneIPCC: AR6, 5.2.2.2 Anthropogenic CH4 emissions
Units and Measures
CH4 emissions are expressed in the total weight in megatonnes per year. 1 Megatonne is equal to 1 million tonnes.
Wikipedia: MegatonneWikipedia: Global warming potential
About the Data
The last available year in all the emission datasets is 2023. Methane emissions come from the PRIMAP-Hist dataset. It is a rich dataset that combines several published sources to create a historical emissions time series for various greenhouse gases.
The Key Insights paragraph was created using a large language model (LLM) in combination with our data, historic events, and a structured approach for best accuracy by separating the context generation from the interpretation and narrative.
Data Sources
PRIMAP-hist The PRIMAP-hist national historical emissions time series (1750-2023)
Update cycle: Every few monthsDelay: Less than 1 yearCredits: Gütschow, Johannes; Busch, Daniel; Pflüger, Mika (2024): The PRIMAP-hist national historical emissions time series (1750-2023) v2.6. Zenodo.