Overview

June 16, 2026 · View on GitHub

Open Methane Prior uses a variety of data sources to estimate emissions from known methane emission sources. Broadly, these data sources fall into two categories:

  • emission estimates from existing sources
  • spatial proxies for methane emissions

Estimates from existing sources

Gridded methane emission estimates have already been produced for some sectors in published research or publicly available datasets. Where possible, these estimates are simply regridded onto the Open Methane grid.

Estimates from spatial proxies

Where no pre-existing gridded estimates are available, the Open Methane Prior estimates emissions by taking the sectoral total from the National Greenhouse Gas Inventory and distributing the emissions based on a spatial dataset that is shown to be a good proxy for methane emissions in that sector.

For example, light pollution is a good spatial proxy for industrial activity. Therefore, a map of nighttime light in Australia can be used to distribute the industrial sectoral emissions from the national inventory spatially. We must take care to ensure that the sectoral estimate and the spatial proxy cover the exact same domain, or the spatial proxy must be masked.

The spatialised estimates are then regridded onto the Open Methane grid.

General data sources

Some data sources are used by multiple sectors of the prior.

Australian State and Territory Boundaries

The official Australian Digital boundary files provide high precision geometries of Australian states, which is used to mask other spatial data sources such as NASA Nighttime Lights.

Australian UNFCCC Inventory

Australia reports GHG emissions broken down by gas and by sector under its UNFCCC obligations. The data is available via the National Greenhouse Accounts web tool, and also via a "Bulk data API".

Specifically, the AR5_ParisInventory_AUSTRALIA dataset contains per-gas emissions broken down by UNFCCC category. This dataset is fetched directly from ANGA, and non-CH4 emissions are discarded, resulting in per-year, per-sector CH4 emissions which can be used as the basis for the total emissions in anthropogenic sectors.

Alongside the inventory data is an inventory domain, which describes the geographic extent where inventory emissions occur. This uses the Open Methane aust10km domain inventory_mask which was developed for this purpose.

UNFCCC CRT categories

To allocate ANGA inventory emissions to prior sectors, we utilise the unfccc_categories in each sector, which contain UNFCCC CRT category codes, like "5" (Waste), "3.B" (Agriculture - Enteric Fermentation). However, the Australian UNFCCC Inventory doesn't include category codes, only full names of the UNFCCC category levels (some of which don't match official forms exactly).

A mapping from ANGA inventory "levels" to UNFCCC codes has been created using an unofficial ANGA API which is used to power the ANGA website. This is necessary because in the past ANGA has made slight changes to level names, and has also added and removed categories from the inventory from year to year.

If this unofficial API changes or becomes inaccessible, we can make the generated UNFCCC codes CSV available via our public data store.

Safeguard Mechanism Baselines and Emissions

Starting in the 2023-24 financial year, Safeguard Mechanism reporting includes per-facility CO2-equivalent emissions estimates for multiple greenhouse gases, including methane. These estimates are provided by the operating entity to the Clean Energy Regulator, and made public in the Safeguard Mechanism Baselines and Emissions Table.

Each "emissions number" reported in the Baselines and Emissions Table uses a unit of "tonnes of carbon dioxide equivalent" (tCO2-e), including the "GHG Methane" number. Based on the CER legislation, this number must be calculated using AR5 global warming potential numbers for CO2 and CH4.

Each facility in the dataset includes an ANZSIC sector classification, which allows us to determine which prior sector the facility should be included in. Lastly, correlating the Safeguard Mechanism facility with a location in a supporting dataset allows us to place those emissions in the correct grid cell or grid cells.

Safeguard Mechanism Facility Locations

The Safeguard Mechanism Baselines and Emissions dataset includes facility-level methane emissions reported to the CER, but the locations of facilities are not made public. The Safeguard Mechanism Facility Locations dataset was created by The Superpower Institute to detail the locations of sites and infrastructure related to each Safeguard facility so that their emissions can be allocated geographically.

The dataset includes two parts:

  • external dataset references
  • direct locations

Where possible, Safeguard facility locations have been identified in other public datasets, such as the National Pollutant Inventory or Climate TRACE. In these cases an external dataset reference is created by recording the Safeguard facility name alongside the DataSource.name of the external dataset and an identifier in the external dataset.

For facility locations that can't be found in existing datasets, research by The Superpower Institute has used company reports, public datasets and satellite imagery to find and document sites and infrastructure related to each facility. These direct locations include a geographical coordinate, and operation dates for locations where the information is available. Each direct location record also includes references to public documents where the information was sourced.

Both of these datasets have been made available via a public, read-only Google Sheet. The public sheet is backed by a private dataset maintained by The Superpower Institute, with data synced using IMPORTRANGE.

Land Use of Australia

Some sectoral inventories are spatialised by identifying which Australian Land Use and Management (ALUM) Classification codes fall within those sectors, and then distributing inventory emissions to the areas where those ALUM codes are featured in the Land Use of Australia geographical dataset provided by the Australian Department of Agriculture.

This is done using a combination of the official Land Use of Australia GeoTIFF raster, and a manual mapping between ALUM codes and Open Methane sectors.

Due to issues fetching the file directly from the agriculture.gov.au service in cloud-hosted services, the land use dataset is mirrored from the Open Methane Public Data Store: https://openmethane.s3.amazonaws.com/prior/inputs/NLUM_v7_250_ALUMV8_2020_21_alb_package_20241128.zip

NASA Nighttime Lights

Sectors which have a strong correlation with human / industrial activity are spatialised using the NASA Nighttime Lights dataset.

The nighttime lights GeoTIFF covering Australia is mirrored from the Open Methane Public Data Store: https://openmethane.s3.amazonaws.com/prior/inputs/nasa-nighttime-lights.tiff

Climate TRACE

Climate TRACE provides a global dataset of greenhouse gas emission sources across many sectors of human activity. Open Methane uses the Australia CH4 "country pacakge" which includes emissions sources such as coal mines and oil and gas production.

The package is available from the Climate TRACE Data page by selecting:

  • View downloads by: Country
  • Select Emission Type: CH4
  • Download the Australia CSV package

Australian National Pollutant Inventory

The Australian National Pollutant Inventory provides a public dataset containing the locations of industrial facilities that emit toxic or harmful pollutants into the environment. They track a variety of harmful substances, and organisations are required to quantify and report any emissions of these tracked substances.

Although the NPI doesn't include greenhouse gases such as methane, the location of industrial facilities in each ANZSIC sector is still a valuable resource for spatialising emissions within a particular industry.

In addition to the facility dataset, NPI data also includes emission data, which includes volumes of each emitted substance at each facility within each reporting period. This currently isn't used in the prior, but may prove useful in the future, if we can identify any tracked substances which can act as a proxy for methane emission.

Data Sources

Sector: Livestock

Australian national dataset of CH4 flux estimates from enteric fermentation in livestock.

Sources

Enteric fermentation emissions generated by CSIRO Ag. and Food using livestock census data and UNFCCC emissions factors. Underlying livestock numbers taken from: "Navarro, J. Marcos Martinez, R. (2021) Estimating long-term profits, fertiliser and pesticide use baselines in Australian agricultural regions. User Guide. CSIRO, Australia."

Considerations

  • Spatial distribution might change during the year since farmers are moving their cows around
  • Doesn't appear to be available online

Alternative candidates

Sector: Termites

Global dataset of CH4 flux estimates from termites.

Sources

Termite emissions used in Saunois et al. 2020 supplied by Simona Castaldi and Sergio Noce.

Considerations

Alternative candidates

Sector: Biomass burning

Global dataset of CH4 flux estimates from biomass burning (wildfires)

Sources

Daily emissions from the Global Fire Assimilation System (Kaiser et al., 2012, doi:10.5194/bg-9-527-2012)

Sector: Wetlands

Sources

Monthly wetland emissions from SatWetCH4, with a wetland extent based on GIEMS. Developed as part of the ongoing [Global Methane Budget](https://www.globalcarbonproject.org/methanebudget/.

  • Dataset: TBD (not yet published)
  • Resolution: 0.25 degree
  • Period: 1992 - 2022, monthly averages
  • Updates: not updated regularly

Considerations

  • No Australian database
  • Rough spatial resolution
  • The paper for this dataset has not yet been published. It was provided to us directly by the leading researcher, Juliette Bernard.

Sector: Agriculture

Agricultural emissions (excluding livestock) reported in the Australian UNFCCC Inventory are spatialised according to the Land Use of Australia dataset.

Sector: Coal

Solid fuel (coal) emissions reported in the Australian UNFCCC Inventory are spatialised according to facility-level estimates.

Facility estimates are taken from Safeguard Mechanism estimates if available, using facility locations published by Climate TRACE.

For facilities not covered by the Safeguard Mechanism, the National Inventory total for solid fuel emissions, minus emissions already allocated to Safeguard facilities, is pro-rated to the facility noted in the ClimateTrace data. The listed point location for each facility is mapped to the relevant grid cell.

Sector: Electricity

Public electricity emissions reported in the Australian UNFCCC Inventory are spatialised according to facility-level capacity.

Sources

The national inventory total for electricity emissions is pro-rated to the location of every facility noted in Open Electricity which is listed for the chosen period. The listed point location for each facility is mapped to the relevant domain grid cell.

Sector: Industrial

Industrial emissions reported in the Australian UNFCCC Inventory are spatialised according to NASA Nighttime Lights.

Sector: Land Use, Land Use Change, and Forestry (LULUCF)

LULUCF sector emissions reported in the Australian UNFCCC Inventory are spatialised according to the Land Use of Australia dataset.

Sector: Oil and Gas

Oil and gas emissions reported in the Australian UNFCCC Inventory are spatialised according to locations of oil and gas boreholes/wells which lie within petroleum titles/leases that were active during the period of interest, and sites and facilities in ANZSIC sectors associated with the oil and gas industries.

Facility estimates are taken from Safeguard Mechanism estimates if available, using facility locations researched by The Superpower Institute.

For wells and facilities not covered by the Safeguard Mechanism, the National Inventory total for "Fugitive emissions from fuels, Oil and Natural Gas", minus emissions already allocated to Safeguard facilities, are distributed equally across all potential emission sources not associated with any SGM facility. Listed point location for each source is mapped to the relevant grid cell.

Sources

Locations of every borehole/drillhole/well in the public datasets from NSW, NT, QLD, SA, WA and NOPTA are correlated with petroleum production titles and filtered to only bores involved in petroleum production where the title period overlaps with the prior period of interest.

Gas supply network emissions are spatialised according to NASA Nighttime Lights masked to the state they have reported their emissions in. Gas pipelines are spatialised using area weighted grid of grid cells each pipeline intersects.

The national inventory total for oil and gas emissions is divided evenly between these sites. The listed point location for each site is mapped to the relevant domain grid cell, where emissions are allocated.

Considerations

The approach used to spatialise the oil and gas sector has several known flaws.

  1. Capped wells

First and foremost, although some datasets list many bores/wells as "capped" or "abandoned", they don't include the date when the capping occurred. For this reason we consider every production well to be an emission source until the date of expiry of the title. This could be incorrect in both ways: wells very likely stop emitting methane when they are capped, and in that case this leads to many false positives within the datasets. Alternatively, capped wells may continue to emit methane after production (and the title) has ended, leading to missing emissions on abandoned fields.

  1. Attribution of inventory emissions

Attribution of equal emissions to every "active" bore/well is also very naive. Wells for different resources (i.e. oil vs coal seam gas) or in different regions (WA vs NSW) or in different infrastructure (onshore vs offshore) are likely to have very different emission profiles. Until we have solid evidence of what these profiles might be, we cannot model them.

Our naive approach attempts to allocate more emissions to facilities and pipelines than to wells, due to the higher volume of resources which pass through each facility.

  1. Missing regions
  • Victoria
    • oil and gas extraction currently entirely offshore, present in NOPTA dataset
  • ACT
    • no oil or gas production to date

Sector: Stationary

Stationary emissions reported in the Australian UNFCCC Inventory are spatialised according to NASA Nighttime Lights.

Sector: Transport

Transport sector emissions reported in the Australian UNFCCC Inventory are spatialised according to NASA Nighttime Lights.

Sector: Waste

Waste sector emissions reported in the Australian UNFCCC Inventory are spatialised according to the Land Use of Australia dataset.

Assets