ReGAME, Reliable Global Methane Emissions Estimates in a Changing World, is a research and innovation project funded by the Research Council of Norway. The project was funded under the call on KLIMAFORSK-Large programme climate.
ReGAME is coordinated by the Climate and Environmental Research Institute NILU and has 7 partners in different European countries. The project runs from January 2021 to December 2025.

Methane is a powerful greenhouse gas, and its ongoing increases threaten to derail the Paris Agreement goal of limiting warming to 2°C. Developments in atmospheric methane are therefore key to assessing climate change and the effectiveness of mitigation strategies. Natural sources include wetland soils, the extent of which is being increased by melting permafrost, forest fires, and geologic processes such as gas seeps and decomposition of subsea gas hydrates. The main CH4 removal process is via chemical processing in the presence of sunlight. To understand the balance of these sources and sinks we will update atmospheric chemistry models by incorporating isotopic signatures characteristic of the various sources and the effects of the removal processes. We will provide top-down emission estimates from an ‘inversion model’, whereby prior estimates of methane emissions are updated to better meet observations.

In REGAME we will update chemistry transport models (FLEXPART, OsloCTM) to include the kinetic isotope effect (KIE) of methane (CH4), enabling better constraints on the CH4 budget (KIE is dependent on source/ sink). We will update the atmospheric inversion framework FLXINVERT to include the novel use of satellite CH4 fields (Sentinel 5P). This will include significant changes to FLEXINVERT, which will also apply to other satellite data e.g. carbon dioxide (CO2) and improve the model capabilities to handle large data fields in general. With these upgrades, we assess CH4 emissions from the major sources (wetlands, biomass burning, anthropogenic) at the global scale using all available data (e.g. ICOS, NOAA data, data on ebas.nilu.no). This data includes measurements from the Zeppelin Observatory in the Arctic, to Troll in Antarctica, i.e. from pole to pole. Our cross-disciplinary team is in a unique position to assess the state of the Arctic/ Antarctic ocean CH4 reservoir. This reservoir is currently considered a minor source but has the potential for large-scale disruption if emissions increase suddenly and rapidly. We will perform measurements of CH4 over the ocean (research vessels Helmer Hanssen, and Kronprins Haakon) to assess temporal variability of CH4 emission from the seabed and movement through the water column (due to e.g. variable microbial activity, ocean stratification, currents and seep emission rates), with long-term (1 year) measurements at a mooring south of Svalbard (deployed for the NorEMSO project) in an area bearing gas hydrates and active CH4 seeps. Furthermore, we add to the knowledge of potential seep locations by performing echo-sounding surveys. Combining insights from these temporal and spatial studies will allow a more targeted approach to assessing the ocean source in general. Specifically in REGAME, we will run a regional/ Arctic inversion including these data to constrain high latitude emissions including from the ocean.

The primary objective of REGAME is to constrain the global CH4 budget

The secondary objectives are to:

Assess the status of CH4 reservoirs such as wetlands and ocean

Survey ocean CH4 seeps in the Arctic and assess temporal variability and dynamics of seep
fluxes

Incorporate isotopic tracers in models (FLEXPART/ OsloCTM)

Develop the use of the Ensemble Kalman Filter method to use S5P CH4 in inversions with
FLEXPART

Investigate the added value of satellite data in inversions

Determine implications of improved CH4 budget and state of CH4 reservoirs for the Paris
Agreement and produce a report for policymakers

ReGAME is structured into 5 working packages (WP). One management/outreach WP and four scientific WPs.

WP1. Atmospheric Observations

WP1 deals with observation data products that will be used in WP4. In coordination with the Institute for Marine Research (responsible for the operation of the vessel), an atmospheric laboratory (flask sampling system, Picarro CRDS) will be installed on the icebreaker RV Kronprins Haakon. This RV will operate over sea ice covered territory in the Arctic and Antarctic. Observations of methane and isotopes over the ocean on the RV Helmer Hanssen with additional measurements from the RV Kronprins Haakon. Analysis of the long-term isotope time series at Zeppelin and preparation of satellite data for inversion.

WP2. Ocean observations

WP2 is dealing with investigating how processes in the ocean environment influence atmospheric concentrations. This includes water column sampling where collecting the samples of seep gas at the sea-bed and analysing its composition will help characterise the type of CH4 reservoir (thermogenic vs microbial). Time series analysis of CH4 from mooring deployed south of Svalbard as part of the NorEMSO project. Insights from WP2 will allow us to include the ocean source more accurately in WPs 3 and 4.

WP3. Updates to models and inversion developments

In WP3, we implement schemes for isotopic fractionation in OsloCTM3 and FLEXPART to model changes in δ13CCH4 and δ13CH4 from all sources and sinks. Developments of the EnKF method using FLEXPART and development of the EnKF method using FLEXPART. Considerable developments will be made to include satellite data in inversions using FLEXPART with the EnKF.

WP4. Model constraints on methane budget

We will combine the information from WP1 and 2 with data from the ICOS and NOAA networks with the improved models to evaluate the CH4 emission inventories using atmospheric inversions: 1) a high-resolution limited domain over the Arctic including data from the RVs to examine high-latitude sources, e.g. northern
wetlands, melting permafrost, and look for any evidence of an ocean source (using FLEXPART/ FLEXINVERT), 2) global inversions using S5P and NOAA data to constrain the global budget (this will use FLEPXART with the EnKF).

WP5. Management / outreach

In Wp5, we will provide an assessment for national and international stakeholders and policymakers and the implications for the Paris Agreement. WP5 also includes the organisation of the project and the important task of formulating data management as well as meetings with an advisory board.