Any jurisdiction or company’s ability to tackle its methane emissions is to a certain extent limited by the data available. Emissions levels and abatement potentials are based on sparse and sometimes conflicting data, and there is a wide divergence in estimated emissions at the global, regional and country levels.

However, given the urgent need to reduce emissions, a lack of perfect information should not impede forward progress on introducing abatement measures. And much greater transparency is coming on methane emissions, thanks to new ground-based and aerial measurements. The increasing availability and accuracy of satellite data is set to be an important part of this process. Satellites are not going to provide all the answers, but they are already providing a way to identify the largest leaks.

There are various satellites in operation today that can provide estimates of the atmospheric concentration of methane across different geographic areas. For example, the satellite Sentinel 5P, part of the European Space Agency Copernicus programme, provides frequent readings of methane concentrations across areas with a resolution of 5 km by 7 km. Satellites operated by GHGSat cover a much smaller area each day but can provide data at a very fine spatial resolution (around 50 m by 50 m) and with a much lower detection threshold; PRISMA, operated by the Italian Space Agency, can provide readings at a 30 m by 30 m resolution. The coverage and accuracy of these readings is only going to improve as additional data becomes available from existing satellites and with the envisaged launches of additional satellites from GHGSat, the German Aerospace Center’s EnMAP, and the Environmental Defense Fund’s MethaneSat.

Changes in the atmospheric concentration of methane can be used to estimate the rate of emissions from a source that would have caused such a change. We have incorporated emissions detected by satellites for the first time in the 2021 update to the Methane Tracker. This relies on data processing by Kayrros, an earth observation firm, to convert readings of concentrations to identify large sources of emissions from oil and gas operations. Reported emissions encompass individual methane sources above 5 tonnes per hour as well as clusters of smaller sources in dense areas (e.g. shale plays).

Large emissions from oil and gas operations that were detected by satellites in 2020 are included in the Methane Tracker for onshore areas in: Algeria, Kazakhstan, Iraq, Kuwait, Russian Federation, Turkmenistan. Readings between January and November 2020 are also included for the Permian and Marcellus shale plays in the United States. Globally, around 5.5 Mt of methane emissions were detected by satellites in 2020.

Emissions detected by satellites are reported as a separate item within the Methane Tracker except for the United States. For the United States, the 2.8 Mt of emissions detected from the Permian and Marcellus shale plays are integrated within total estimates for unconventional oil and gas production. In all countries, emissions are assigned either to upstream or downstream operations based on the geographic location of directly-observed emissions events. These readings are also used to inform estimates of emissions that may be occurring in countries that cannot currently be observed directly by satellites.

The increasing amount of data and information from satellites will continue to improve global understanding of methane emissions levels and the opportunities to reduce them. However, satellites do have some limitations:

• Existing satellites do not provide measurements over equatorial regions, northern areas or for offshore operations. This means that there are a large number of major production areas (e.g. in areas that are often covered with snow) where emissions cannot be directly detected by satellites. The 5.5 Mt of emissions detected by satellites that are included in the Methane Tracker come from areas that provide around one quarter of global oil and gas production in 2020.
• Existing satellites should be able to provide methane readings globally on a daily basis but this is not always possible because of cloud cover and other weather conditions. Sentinel 5P readings for 2020 were also affected by a data outage that reduced the number of direct observations that are currently available (these should be available at a later date). The 5.5 Mt of emissions included in the Methane Tracker is the estimate after an upward revision of directly observed leaks in 2020 to account for the lack of perfect coverage.
• Satellites provide data for large emitting sources. They may fail to capture small-scale emissions sources such as faulty components, which could add up to a large overall amount of emissions.
• The process of using changes in the atmospheric concentration of methane to estimate emissions from a particular source can rely on a large level of auxiliary data and be subject to a high degree of uncertainty.

The country-by-country emissions levels in Methane Tracker include estimates for emissions from large-emitting sources, even if they have not been directly observed by satellite. This is, of course, subject to a high degree of uncertainty, but we do so to ensure that our country-by-county estimates provide a comprehensive picture of all methane emissions sources. As additional data becomes available from measurement campaigns – whether recorded from ground or aerial processes or by satellites – we will incorporate these into the Methane Tracker and adjust estimates accordingly.