IEA (2022), Global Methane Tracker 2022, IEA, Paris https://www.iea.org/reports/global-methane-tracker-2022, License: CC BY 4.0
Estimating methane emissions
There are large differences between data based on measurement campaigns and scientific studies, and the emissions levels reported by official public bodies, such as to the UN Framework Convention on Climate Change (UNFCCC), that rarely make use of direct measured data. This mismatch exists at both global and national levels and for all sources of emissions. Many official greenhouse gas submissions to the UNFCCC have not been updated for years, and, even for those that have, many of these inventories are not yet accurate enough to provide a clear picture of emissions.
Methane emissions can be estimated in a number of ways. Bottom-up approaches can use activity data (e.g. the number of facilities or the extent of operations) multiplied by standardised emission factors (e.g. default values or leak rates for particular types of equipment). Top-down methods tend to measure atmospheric methane concentrations, normally by airborne or satellite sensors, to infer emission releases.
Estimates are subject to significant uncertainty over the magnitude of emissions sources and their variability. Some of the largest emitting events are the result of accidents and unpredictable process failures and these might contribute a large level of emissions from oil and gas operations, but these are often not included in bottom-up inventories. Tried and tested approaches are already available for lowering methane emissions, but better and more transparent data are needed to facilitate targeted action.
Incomplete information about actual emission levels and a lack of awareness or the cost-effectiveness of abatement is a key barrier to reducing methane emissions. In response, a growing number of recent initiatives aim to measure and report current and historical emissions from facilities, production types and countries. Yet these assessments remain incomplete – most countries and regions still have little or no measurement-based data and the data they provide often require careful processing. These gaps highlight the need for robust and transparent data evaluation and harmonisation of estimates.
The International Methane Emissions Observatory (IMEO), established by the UN Environment Programme with support from the European Union, is an initiative that aims to commission measurement studies and to integrate measured data from a range of sources. This includes company reporting through the Oil and Gas Methane Partnership 2.0 Framework, direct measurements from peer-reviewed studies, satellite observations, and national inventories. These empirically verified data will be provided in a public dataset to inform companies, governments, investors, and civil society as they work together to track methane emissions levels and abatement efforts. The IEA strongly supports IMEO and maintains a strong ongoing dialogue with the Secretariat and the Scientific Oversight Committee.
IMEO will hasten the availability of validated, reliable, and measurement-based data on methane emissions, and help to reduce uncertainty in the levels, location and temporal variability of global methane emissions. This integrated data product will take time to comprehensively characterise emissions and, therefore, estimates included in the IEA’s Global Methane Tracker will play an important complementary role, reflecting the IEA’s evolving understanding of the level and distribution of all energy-related methane emissions.
Advances in monitoring technologies, notably from satellites, have been a key to boosting our understanding of the level and nature of methane emissions. Current satellites and data processing techniques can be used to detect and quantify total emissions from major leaks over a large area, down to small leaks at the facility level.
New satellites are being developed that will provide higher resolution, greater coverage, and have more sensitive detection thresholds. These include instruments such as EnMAP, Carbon Mapper, SBG, CHIME and EMIT and MethaneSAT that aim to deliver high-resolution images for selected high-priority areas. These will improve methane quantification capabilities, raise public awareness and support regulatory oversight.
Satellite technologies are not perfect. They can struggle to provide readings in many environments such as offshore areas, mountain ranges, snowy or ice-covered regions, and at high latitudes. They are also impaired by cloud cover, even if only a portion of the monitored area is covered, limiting the number of days when detections can be made. For example, countries with dense forests or in equatorial regions, such as Nigeria or Venezuela, are very often cloudy, hindering observation efforts.
Data from the European Space Agency satellite Sentinel 5-P, processed by the earth analytics firm Kayrros, indicates that during 2021 there were around 70 countries where methane emissions from oil and gas operations could be detected for at least 15 days. Large emission events were observed in around 15 of these countries in 2021. Coverage tends to be best in the Middle East, where a direct measurement could be made every 3-5 days. On the remaining days, cloud coverage or other interference prevented measurement operations. Accounting for the level of satellite coverage, very large emitting events detected by satellite are estimated to have been responsible for around 3.5 Mt of emissions from oil and gas operations in 2021 (6% of our estimate of oil and gas emissions in the 15 countries where events were detected).
Other detection and measurement campaigns will remain essential, and the optimal system will combine satellite measurements with drone-based and other aerial surveys, ground-based sensors and surveys, and continuous monitoring devices. Beyond measuring, robust monitoring, reporting and verification procedures and systems are also essential.
A thorough picture of methane emissions is a prerequisite to design policy tools that can drive deeper cuts in emissions in an efficient manner, including market-based instruments, performance standards and trade measures. It can also facilitate the work of regulators in verifying compliance and in tracking progress against reduction targets, support regulatory development and enable other stakeholders to engage with methane mitigation efforts.
The IEA produces and publishes country-level estimates for energy-related methane emissions and abatement options as part of our IEA Global Methane Tracker. The 2022 update also includes emissions estimates from non-energy sectors – waste and agriculture – based on publicly available data sources, to provide a fuller picture of methane sources from human activity.
Our estimates are regularly updated using the best available data on fossil fuel operations, country- and production-specific emissions intensities, as well as measurement campaigns and large emissions events detected by satellites. We also work with IMEO to ensure our estimates reflect the latest findings from measurement-based, peer-reviewed studies. Further details on the methods used can be found here.
The 2022 update, for the first time, includes emissions from coal operations, in addition to oil and gas operations. These are based on satellite-based measurements, inverted atmospheric methane measurements, and reported data from the largest coal producers (the People’s Republic of China, the United States and India). Emission intensities are derived on a mine-by-mine basis according to coal quality (e.g. the ash content or fixed carbon content of coal produced by individual mines) and mine depth. These emission intensities are transposed to mines in countries without reliable direct estimates based on a range of auxiliary data such as the strength of regulation. Global coal-related emissions are estimated to total 42 Mt in 2021, around one third of methane emissions from energy.
We estimate that about 9 Mt of methane emissions comes from bioenergy, due to incomplete combustion during the traditional use of biomass for cooking in emerging market and developing economies. This highly polluting process is a major source of indoor air pollution and is responsible for around 2.5 million premature deaths every year.
With fossil fuels, methane emissions can occur at any point during production, processing, transport, up to and including end use. We include emissions from the end use of oil products and natural gas for the first time in the 2022 Global Methane Tracker (4 Mt or 3% energy-related methane). This estimate is based on the emissions factors published by the Intergovernmental Panel on Climate Change for energy consumption in homes, industries and in the transport sector. Some measurement campaigns have suggested that these emissions factors could significantly underestimate actual emissions across different end-use environments, including in industry, cities and households. These are areas with very high levels of uncertainty and our estimates will continue to be updated as the evidence base grows.
Emissions from abandoned coal mines and oil and gas wells are not included in the Global Methane Tracker: existing measurements cover a limited number of facilities and regions, and reliable data on abandoned mines and wells is not available for most countries. These sources could, nonetheless, represent significant levels of emissions. The U.S. Environmental Protection Agency indicates they are responsible for close to 5% of energy-related methane in the United States; and a recent study estimated that abandoned mines could account for almost one fifth of methane emissions from worldwide coal production.
The IEA Global Methane Tracker 2022 is our best attempt to reconcile existing information and produce a consistent set of country-level estimates. We recognise these estimates do not represent the last word. We welcome all feedback based on measurement campaigns and robust data sources that can further refine our estimates. You are welcome to share relevant reports or scientific studies by email at MethaneTracker@iea.org.