Editing Methane emissions mass flux (CH4)

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{| class="wikitable" style="float:right; clear:right; margin:0 0 1em 1em; width:320px;"
|+ SIGNAL Earth Structured Data
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! Object type
| Damage Signal
|-
! SIGNAL Earth ID
| DS-00042
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! Observable type
| Methane emissions mass flux (CH4)
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! Unit
| kg CH4/year (kilograms of methane emitted per year)
|-
! Temporal structure
| Periodic
|-
! Monitoring backbone
| —
|}
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{{SignalTerm|type=DS|id=DS-00042|label=Methane emissions mass flux (CH4)}} represents the total mass of methane gas released into the atmosphere over a specified period, typically expressed in kilograms of CH4 per year. Methane is a potent greenhouse gas with a global warming potential significantly higher than carbon dioxide over a 20-year timeframe, making its emissions a critical factor in climate system forcing. Understanding the magnitude and sources of methane emissions is essential for assessing anthropogenic and natural contributions to atmospheric composition and climate change dynamics. This damage signal quantifies methane emissions as a driver within the air domain, providing insight into pressures exerted on the climate system.

== Geographic / System Context ==
Methane emissions occur globally, originating from a diverse range of geographic systems including wetlands, agricultural lands, fossil fuel extraction and processing sites, landfills, and biomass burning regions. The spatial distribution of methane fluxes varies according to natural ecosystem characteristics, human activities, and climatic conditions. Wetlands, for example, are the largest natural source of methane, while fossil fuel infrastructure and agriculture contribute significantly to anthropogenic emissions. Monitoring and understanding emissions across these varied geographic contexts is vital for comprehensive global assessments.

== Monitoring and Measurement ==
Methane emissions are monitored using a combination of ground-based measurements, airborne campaigns, and satellite remote sensing technologies. Scientific institutions employ atmospheric sampling, flux chamber measurements, and eddy covariance techniques to quantify local emissions. Satellite instruments provide spatially extensive observations, enabling estimates of regional to global methane fluxes. Data integration from multiple platforms supports the development of emission inventories and budget assessments. The Global Methane Budget initiative synthesizes such data to provide periodic updates on methane sources and sinks worldwide.

Within the SIGNAL system, methane emissions mass flux (CH4) is treated as a defined environmental signal whose boundaries and measurement conventions are described below.

== Signal Definition ==
Methane emissions mass flux (CH4) quantifies the total mass of methane emitted into the atmosphere from all sources within a defined spatial and temporal boundary. It is expressed in kilograms of methane per year (kg CH4/year) and reflects the net release of methane molecules contributing to atmospheric concentrations. This signal represents a pressure or stressor on the climate system through its role as a greenhouse gas forcing agent.

== Boundary Conditions ==
Boundary inclusions encompass all methane emissions to the atmosphere from natural and anthropogenic sources, including wetlands, agriculture (e.g., enteric fermentation, rice paddies), fossil fuel extraction and processing, landfills, and biomass burning. Boundary exclusions typically involve methane present in the atmosphere not directly attributable to emissions within the defined temporal or spatial scope, such as methane transported from outside the study area or methane removed by atmospheric chemical reactions. Emissions from oceanic sources and geological seepage are included when quantifiable but may be subject to data availability constraints.

== Aggregation Semantics ==
Geographic aggregation involves summing methane emissions across spatial units ranging from local sites to global scales, enabling regional and global flux estimates. Temporal aggregation is periodic, typically annual, to capture seasonal and interannual variability. Cross-signal aggregation may integrate methane emissions with related environmental signals such as atmospheric methane concentration and fugitive hydrocarbon emissions to provide a holistic view of methane dynamics and their climate forcing implications. Aggregated data support trend analysis, source attribution, and modeling efforts.

== Observational Status ==
Current monitoring efforts provide periodic global estimates of methane emissions, with ongoing improvements in spatial resolution and source attribution. Data gaps remain in some regions and source categories due to limited measurement coverage or methodological challenges. Future SIGNAL releases aim to incorporate enhanced monitoring backbones, including advanced satellite retrievals and expanded ground-based networks, to improve temporal frequency and spatial detail. Integration with related signals will further refine understanding of methane's role in climate forcing.

== Related Signals ==
* Global mean atmospheric methane concentration (global)
* Hydrocarbon fugitive emissions from gas processing and liquefaction
* Methane slip emissions to air from LNG-fueled shipping

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== Key Associated People ==
* '''M. Saunois''' (Université Paris-Saclay / LSCE) [Lead author]
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== Sources ==
* [https://essd.copernicus.org/articles/17/1873/2025/essd-17-1873-2025.html Global Methane Budget 2000–2020 — 2025]
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