The Global Methane Budget

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences


Methane is the second most important greenhouse gas contributing to human-induced global warming. Atmospheric methane concentrations have increased sharply since 2007, and dramatically in 2014, for reasons that are not understood.

The overall increase since 2007 is comparable to the largest growth events over the past 1000 years. The recent rises have occurred worldwide, but after an Arctic pulse in 2007, the growth has been primarily in the tropics and southern hemisphere. Strong growth continues in 2015. Carbon isotopic evidence suggests that the increase is due to sources that are predominantly biogenic in origin, with changes in the anthropogenic sources from fossil carbon and burning (e.g., natural gas leakage, coal mining and so on) playing a subordinate role. This, taken with the tropical locus on growth, suggests that the increase has primarily been driven by meteorological change (e.g., temperature, rainfall).

Moreover, the global methane budget is currently not well understood. "Bottom-up" estimates, made by aggregating inventories of emissions (e.g. from gas leaks, fires, landfills, cows, etc) or from process models (e.g., wetlands) balanced with known loss processes, are significantly different from '"top-down" budgets assessed by direct measurement of methane in the atmosphere. Why this discrepancy occurs is not known.

The project has four components:
1. Better Observations are needed to derive estimates of emissions. The project will support a UK observation network for methane and its isotopes. Continuous stations will be at Kjolnes (Norway), Weybourne, Jersey, NERC ship RRS JC Ross, Cape Verde, Ascension, Falklands, Halley Bay, Hong Kong, with partner stations in Canada, Spitsbergen, Bolivia, S. Africa, India, Rwanda and Malaysia. Flask or bag sampling (for methane, 13C and D/H isotopes) will also be undertaken at these stations and at a number of continental stations in S. America, Africa and S, SE and E Asia, with offline analysis in the UK. A D/H measurement facility will be set up. The UK FAAM aircraft will carry out flights across the Atlantic tropics, from Azores to Cape Verde to Ascension.

2. Process Studies will address the largest information gaps in the global budget. Tropical emission fluxes and isotopic signatures are not well constrained. Field campaigns will be undertaken in tropical wetlands in Amazonia, Africa, India and SE Asia, and C4 savanna biomass burn regions. Poorly understood anthropogenic sources will be studied in Kuwait and S, SE and E Asia. Characteristic isotopic signatures of regional emissions will be determined, to support global and regional modelling. Land surface modelling and satellite studies will study emissions and responses to change in temperature and precipitation. Major sink processes will be investigated in the tropical atmosphere, with vertically and latitudinally resolved OH and Cl budget studies by the FAAM aircraft, and quantification of tropical uptake by soils.

3. Atmospheric modelling will be used to derive regional and global fluxes, apportioned by source type and geography using integrated in situ and remote sensing observing systems. We will carry out regional trajectory studies using models like NAME to assess regional emissions. Global modelling using 3D models will test synthetic estimates of the methane mole fraction and isotopic record. Global inverse modelling for mole fraction, 13C and D/H will be used to estimate fluxes by geographic source and source type, including a comprehensive assessment of the uncertainties that remain once all available observations have been used.

4. Integrative studies will use the results from the project to test top-down and bottom-up emission estimates, and evaluate the responses of the global methane budget to projections of climate change.

The project will deliver a state of the art greenhouse gas monitoring network and much better knowledge of the global methane budget.

Planned Impact

This project will produce a much better understanding of the global methane budget, and the role of climate feedbacks in driving emissions. The sharp increase of atmospheric methane since 2007 will be of major public interest.. Simultaneously, there has been a shift in its carbon isotopes implying the increase is primarily biogenic, not driven by fossil fuel emissions. A better knowledge of the global methane budget is vital if we are to understand what is driving climate change and predict future emissions. This work will have impact on a very wide range of beneficiaries, from scientists to policy-makers.

Measurement: The project will create an Observation network as a long-term outcome, to sustain and improve global methane mole fraction and isotopic measurement, especially in the tropics where data gathering is presently very weak. In particular, the project will continue the greenhouse gas measurement on Ascension Is., one of the very few tropical background stations globally, and currently unfunded from 2017. The data will be invaluable to modellers.

Policymakers: With the Paris Climate Conference later this year, policy makers and governmental bodies are strongly focussed on climate change. 195 nations participate in the United Nations Framework Convention on Climate Change (UNFCCC). This commits signatory countries to assess their greenhouse gas emissions. For methane, there is a major discrepancy between global total emissions as assessed by atmospheric measurement ('top-down' measurement) and the sum of national emissions declared under UNFCCC (the 'bottom-up' inventory). This project will make major advances towards resolving this problem.

Space: When Sentinel 5P, GOSAT-2 and MERLIN satellites are launched, this project's in-situ observation of equatorial and Southern Hemisphere methane will make a significant contribution to analysis of the satellite measurements and will help validate the TCCON station at Ascension Island, a key equatorial site for satellite ground-truthing.

In the modelling component of the project, interpretation of the observations will help ecologists and geographers understand the impact of climate change globally and especially in less developed nations. There will be strong impact on those carrying out global security studies, benefitting from the significant improvement the work will bring to greenhouse gas emissions inventories in tropical nations, where methane is very poorly constrained at present. The work will support marked improvements in emissions estimate for these nations.

In the private sector, a direct beneficiary will be Isoprime Ltd. (Cheshire: Queen's Award 2013), who will partner the development of the D/H analysis system at Royal Holloway. Wider beneficiaries include the gas, coal and oil industries, as the strong improvement of isotopic work, especially in D/H, will facilitate leak identification and location. Cutting leaks will improve efficiency and productivity as well as help compliance with regulatory frameworks.

Education: The project will support a number of younger staff, who will sustain the UK's key skills in greenhouse gas measurement and modelling, especially in the use of isotopes to characterise emissions. Career development will come through skills learned, publications, conferences, and training opportunities.

Public/Media: The results of this work will also be of interest to the wider public. Greenhouse gas, global warming and climate change are high on the political and media agenda, especially with the Paris climate conference later this year. Decisions made there will have implications for all.

Methane and its feedbacks rank among the most important and the most poorly understood problems in the global climate system. In wide global constituencies, from specialist scientists to policy makers, there is great need for better knowledge. Thus this project will have unusually strong and very wide impacts worldwide.


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Description Aircraft-based field work using the FAAM aircraft ( was conducted over Senegal (March 2017) and over Uganda and Zambia (Feb/March 2019) to measure and quantify emissions of methane (and other trace gases) from biomass burning, cities, and tropical wetlands. Using this data, we have calculated and published new emission factors for burning of biomass in Senegal and Uganda, which will allow others to reassess the global contribution of biomass burning to total global methane emissions. Also, we have identified strong methane emissions from swamps and wetlands in Zambia, which will allow further assessment of the role of tropical wetland emissions in the global methane budget. A further field study using the FAAM aircraft in northern Sweden in July 2019 has collected data that will be used to calculate carbon fluxes from Arctic wetlands in the summer growing season. The Arctic is a key region of concern with respect to future climate change and how carbon emissions feedbacks may become realised.
Exploitation Route The new assessments of biomass burning and wetland methane emissions may be used by greenhouse gas budgeting scientists to update our knowledge of the drivers of climate change/radiative forcing, as a result of methane emissions. This may allow more targeted emissions mitigation policy and a better predictive capacity for future climate change scenarios.
Sectors Agriculture, Food and Drink,Energy,Environment

Description The published findings of MOYA research have led to a new focus on tropical methane emissions from wetland sources in particular and their contribution to the global methane budget, including whether such sources may be increasing in response to positive climate feedbacks.
First Year Of Impact 2022
Sector Environment
Impact Types Societal

Description Strategic Programme
Amount £5,000,000 (GBP)
Funding ID NE/N015835/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 05/2016 
End 04/2020
Title MOYA: ground station and in-situ airborne observations by the FAAM BAE-146 aircraft 
Description All aircraft data from FAAM campaigns as part of the MOYA project Facility for Airborne Atmospheric Measurements; Natural Environment Research Council; Met Office (2017): MOYA: ground station and in-situ airborne observations by the FAAM BAE-146 aircraft. Centre for Environmental Data Analysis, date of citation. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact This public dataset was used in all publications led by the University of Manchester as part of the MPYA project. 
Description British Geological Survey 
Organisation British Geological Survey
Country United Kingdom 
Sector Academic/University 
PI Contribution Work Package lead of atmospheric composition deliverable to an environmental baseline assessment prior to potential shale gas production in the UK
Collaborator Contribution Part of a broader project tasked with a full environmental baseline assessment. BGS have provided eddy covariance monitoring instrumentation to our measurement site at Blackpool and provide knowledge exchange on broader environmental assessment, e.g. seismic and ground water assessments and monitoring.
Impact Project website (above). Contributions to public inquiry evidence. Multi-disciplinary - atmospheric science, geology, seismology, hydrology, satellite remote sensing, public health.
Start Year 2014
Description Environment Agency - UAV GHGs for Landfill flux 
Organisation Environment Agency
Country United Kingdom 
Sector Public 
PI Contribution Designed, built and operated a drone for greenhouse gas (CO2 an CH4) sampling in support of regulatory monitoring of GHG flux from UK landfills.
Collaborator Contribution Funding and guidance on development for regulatory uses and commercial roll-out to environmental consultancies.
Impact Allen, G., Pitt, J., Hollingsworth, P., Mead, I., Kabbabe, K., Roberts, G., Percival, C.: Measuring landfill methane emissions using unmanned aerial systems, Environment Agency, ISBN 978-1-84911-367-0, SC140015/R, 2015 Allen, G., Feasibility of aerial measurements of methane emissions from landfills, Environment Agency, ISBN 978-1-84911-329-8, SC130034/R
Start Year 2016