The Global Methane Budget

Lead Research Organisation: University of Leicester
Department Name: Physics and Astronomy


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 Satellites provide a powerful new resource to constrain regional emissions of methane and thus they provide a powerful datasets that helps to advance the global methane budget. Using satellite data we could show the importance of seasonal flooding to regional methane emissions from wetlands, a process not well captured by current models.

Furthermore, as shown in Lunt et al., tropical Africa plays. key role for the regional methane budget, But a key uncertainty is the quality of Satellite CH4 data for Tropical Africa. We have acquired a unique column dataset in collaboration with the NaFIRRI institute in Jinja, Uganda, which represents an important and novel dataset that allows us to evaluate models and satellite datasets for this regions.
Exploitation Route A key way to take our findings forward is in the context of verifications to methane emissions on a national level as part of the reporting to the UNCCC.
Sectors Environment

Description Our collaboration with research organisation in Uganda (especially NaFIRRI) is leading to significant knowledge exchange and helps to upskill researchers in Uganda. This has already helped to develop research proposals submitted by our Ugandan partners (eg submitted to the Royal Society).
First Year Of Impact 2019
Sector Environment
Impact Types Societal

Description Detection and Attribution of Regional greenhouse gas Emissions in the UK (DARE-UK)
Amount £200,586 (GBP)
Funding ID NE/S003746/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 03/2019 
End 03/2023
Description Development of Operational Prototype of GHGWatch
Amount £297,509 (GBP)
Organisation UK Space Agency 
Sector Public
Country United Kingdom
Start 09/2021 
End 03/2022
Description GHGWatch - a multi-sensor approach to Greenhouse Gas Detection,
Amount £226,295 (GBP)
Organisation UK Space Agency 
Sector Public
Country United Kingdom
Start 11/2020 
End 03/2021
Title Autonomous operation of column measurements in tropical Africa 
Description As part of the MOYA project we have as the first group, deployed a new generation of column sensors to tropical Africa using fully automated system. 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? No  
Impact This development will allow other research group using similar portable sensors to operate under human and hot conditions. 
Description Collaboration with researchers from NaFIRRI in Jinja, Uganda 
Organisation Government of Uganda
Department National Fisheries Resource Research Institute
Country Uganda 
Sector Public 
PI Contribution We have established a new collaboration with researchers from from NaFIRRI in Jinja, Uganda . As part of this collaboration we will provide a instrument for measurements of total columns of methane (and other tracers) and we will work with local researchers on the scientific interpretation.
Collaborator Contribution Researchers from NaFIRRI are hosting and operating a column methane instrument provided by University of Leicester and they will contribute to the scientific interpretation.
Impact So far, the partnership has resulted in an memorandum of understanding and several exchanges. We have no setup the instrument at NaFIRRI in Jinja and the instrument collects data since beginning of this year.
Start Year 2018
Description Sentinel 5P 
Organisation European Space Agency
Country France 
Sector Public 
PI Contribution Develop a partnership with the ESA Sentinel 5P validation team (for methane) that will allow to link ground-based and model data to novel satellite observations
Collaborator Contribution ESA will provide access to Sentienl 5P data and the required instrument infromation to fully exploit the data in support of MOYA
Impact We have presented the MOYA campaing plans at the ESA S5P validation workshop. We are now also the lead for the UK activities in this area.
Start Year 2018