UNEP’s International Methane Emissions Observatory (IMEO) exists to provide open, reliable and actionable data to the individuals who can act to reduce methane emissions. It draws on data from satellites, scientific research, government inventories and company reporting to drive transparency and accountability.

With credible data, IMEO provides stakeholders the means to prioritize and target actions on methane and track variation of emissions over time. This is key to unlocking progress at the speed and scale required to meet climate targets like the Global Methane Pledge, which aims to reduce global methane emissions 30% by 2030 and of which IMEO is a core implementing partner.

IMEO is committed to producing a global public dataset of empirically verified methane emissions – starting with the fossil fuel sector – at an increasing level of granularity and accuracy.

IMEO Methane Data is currently in its beta phase and will be iterated with new data and features. The current beta version is focused on satellite data and the MARS system, with information on scientific measurement campaigns initiated by IMEO.

UNEP’s IMEO Methane Data is the most comprehensive source of satellite-detected methane plumes from point sources. Unlike other data platforms, which focus on providing data from one or two point source imagers, this site provides data from all methane-detecting satellites with publicly available data.

UNEP’s IMEO provides specialized remote sensing expertise to properly interpret results into methane emissions Additionally, all data shared here are validated and checked for false positives by UNEP IMEO satellite data experts.

Satellites measure solar light reflected by the Earth s surface. Using specialized sensors that are sensitive to the specific wavelengths of light that methane molecules absorb, these satellites can measure the amount of methane in the atmosphere.

A more detailed explanation of satellite methane detection can be found in Jacob et al., 2022.

Methane-detecting satellites can be categorized as area flux mapper satellites and point source imagers Jacob et al., 2022..

Area flux mappers such as the European Space Agency s TROPOMI instrument on the Sentinel-5P satellite can be used to quantify total methane emissions on regional-to-global scales and to determine hotspots, or regions of enhanced methane concentration resulting from one or more persistent emissions sources. Additionally, these satellites can detect very large (more than 10 tonnes methane per hour) individual methane plumes.

Area flux mappers have the advantage of seeing most of the planet each day, albeit at lower pixel resolution. These make them ideal for determining locations to explore more in-depth with high-resolution point source imagers.

Point source imagers have pixels on the order of less than 60 m x 60 m and can attribute observed methane emissions plumes to the facility-scale source, a necessary step to notify operators of emissions

The table below shows the publicly available satellites being used by UNEP IMEO. Additional details on these and other methane-detecting satellites can be found on the Committee on Earth Observation Satellites (CEOS) Greenhouse Gas Satellite Missions Portal and in Jacob et al., 2022..

UNEP IMEO has partnered with the Netherlands Institute for Space Research (SRON) to obtain Sentinel-5P/TROPOMI hotspot data, which is used by the UNEPs Methane Alert and Response System (MARS) to target higher-resolution point source imagers to regions of interest (see: MARS FAQ). Kayrros SAS has also partnered with UNEP’s IMEO to provide detection of very large methane plumes from Sentinel-5P/TROPOMI through their Methane Watch platform.

For point-source imagers, UNEPs IMEO uses the existing suite of Earth Observation satellites to detect, localize, and quantify large emission sources globally. These satellites currently include:

• European Space Agency (ESA) Sentinel-2 and Sentinel-3
• Italian Space Agency (ASI) PRISMA
• Germany’s (DLR) EnMAP
• National Aeronautics and Space Administration (NASA) EMIT aboard the International Space Station (ISS)
• National Oceanographic and Atmospheric Administration (NOAA) GOES
• NASA/United States Geological Survey (USGS) Landsat 8 and Landsat 9.

Data from these satellites is publicly available, though in some cases specialized remote sensing expertise is required to properly interpret these data and provide them in the format of methane emissions estimates. UNEP provides this expertise to the global community to help further the goals of the Global Methane Pledge.

There are some fundamental limitations to using satellites for detecting emissions, tracing them to their sources, and quantifying how much methane is being released into the atmosphere.

First, satellites can only detect methane when sunlight is available and where there are no clouds. This is because satellites detect methane using sunlight reflected from the Earths surface. It makes it difficult or impossible for satellites to detect methane emissions in persistently cloudy areas of the globe.

Second, the brightness and topography of the Earths surface that reflects sunlight back to a satellite also influences whether a source of methane can be detected. It is difficult for satellites to observe methane over or near water or snowy areas, in densely forested or complex regions (e.g., mountains or cities), and where there is reduced sunlight (e.g., high northern latitudes).

Any satellite also has a Minimum Detection Limit (MDL), which means that it cannot observe methane unless it is present at or above a specific concentration. While satellites are often capable of detecting large emission events(greater than 1,000 kg methane per hour for current public satellites), its also important to address the many smaller sources of methane that in aggregate make up a majority of the worlds methane challenge.

Methane ‘hotspots’ are locations with average elevated methane concentration indicative of one or more individual sources.

Sentinel-5P, equipped with the TROPOMI instrument, provides daily global methane concentration data at a resolution of 7 x 5.5 km2. The methodologies for detection of methane ‘hotspots’ is found in Maasakkers et. al. (2022) and Schuit et. al. (2023). Attributing emissions to facilities requires higher-resolution spatial data than is provided by Sentinel-5P.

Currently, for each detection we provide the date and time of observation; the latitude, longitude, and country of the plume origin, an emission estimate plus uncertainty, and the relevant sector of the emission.

For Sentinel-5P/TROPOMI plumes these have an estimated uncertainty of ± 50 km (Lauvaux et al., 2022). Additionally, for higher-resolution plumes, we currently provide the outline of the methane plume mask (in orange), later to be replaced with a heatmap visual of the methane plume. For these plumes, location uncertainty is reduced to a few meters (between 20 and 60 m, depending on the resolution of the satellite).

Hyper-spectral satellites such as PRISMA, EnMAP, or EMIT have high spatial (30 m x 30 m to 60 m x 60 m pixels) and high spectral resolution. They feature numerous spectral channels keyed to methane’s strong methane absorption features around 2300 nm.

Methane retrievals from these satellites are computed using a Match-Filter approach, as detailed in Irakulis-Loitxate et. Al. (2021), which involves detecting methane’s absorption spectrum using statistics extracted from the hyperspectral image. Radiative transfer simulations are subsequently utilized to derive per pixel methane concentrations. Most of these missions require a tasking process, i.e., data users must specify in advance the locations of interest and make targeted requests.

Multi-spectral satellites, such as Sentinel-2, Landsat-8, Sentinel-3 or GOES, offer frequent and extensive observations across vast regions, albeit with a lower sensitivity to methane. Under certain favourable observation conditions, such as strong emissions and background homogeneity, methane retrievals can be performed using the Multi-Band-Multi-Pass approach. This method, as detailed in studies by Varon et. Al. (2021), Pandey et. Al. (2023) and Watine-Guiu et. Al. (2023 – preprint), leverages the varying levels of absorption in various shortwave infrared spectrum bands when methane is in the satellite’s line of sight. Radiative transfer simulations are similarly employed to derive per pixel methane concentrations.

Quantification of methane emissions from a single satellite observation involves measuring the instantaneous source rate, reflecting the emission rate at the time of observation. We utilize the Integrated Mass Enhancement (IME) method (Varon et al., 2018), which calculates the total mass of methane by integrating the concentration detected in each pixel over the entire area of the observed plume. To determine the source rate, an empirical linear relationship is applied, incorporating the effective wind speed and the length of the plume, as described by Frankenberg et. al. (2016).

Geostationary satellites like GOES, which covers the Americas, enable continuous monitoring of methane emissions with observations every 5 minutes. This enables the estimation of not only the instantaneous source-rate, but also the total amount of methane emitted during an event. The IME method is employed to determine the presence and quantity of methane in each 5-minute snapshot (Watine-Guiu et al., 2023-preprint).

Satellite estimates of methane emissions from individual point sources has been tested and validated using single-blind controlled-release experiments, where a known amount of methane is released at a known rate and then retrieved and estimated by satellites (Sherwin et al, 2023a; Sherwin et al., 2023b). This type of testing has shown satellites to be well-suited to estimate, within their stated uncertainty, the emissions of individual point sources.

Point sources are an important component of the total amount of methane emissions, accounting for a significant fraction of basin-wide emissions depending on the minimum detection limit of the instrument (e.g., Sherwin et al, 2023a). These typically very large methane plumes also represent a ‘low-hanging fruit’ opportunity for mitigation, which UNEP IMEO addresses through the Methane Alert and Response System (MARS) data-to-action initiative.

However, these point source measurements are not representative of the total amount of emissions – which must ultimately be accounted for using, for example, area flux mappers and other observations – in order to understand the full impact of a sector on climate. While UNEP IMEO is first focusing on point-source data, once more advanced area flux mapper instruments are launched (e.g.,MethaneSAT ), this site will incorporate emissions from area sources not accounted for by point source imagers.

UNEP’s IMEO supports multi-scale scientific measurement studies around the world to fill existing knowledge gaps about where methane emissions are coming from and what actions are needed to address them. The studies are all led by academics and scientists, and make a difference by focusing on regions and/or sources where little to no publicly available data exists. IMEO’s science studies support and foster actions from governments, industry, and other stakeholders to reduce emissions of methane and curb global warming. Learn more about UNEP’s IMEO methane science studies here.

Studies are published in the peer-reviewed literature. A list of past, current, and ongoing studies, along with available publications, can be found here.

Information for interested parties on how to propose a science study can be found here.

The Oil and Gas Methane Partnership 2.0 (OGMP 2.0) is the United Nations Environment Programme’s flagship oil and gas reporting and mitigation programme. OGMP 2.0 is the only comprehensive, measurement-based reporting framework for the oil and gas industry that improves the accuracy and transparency of methane emissions reporting. This is key to prioritising methane mitigation actions in the sector. If you can’t measure it, you can’t fix it. More information can be found here.

In the future all aggregated company data reported under the OGMP 2.0 will be available on the platform. There will be a clear distinction between those data that are estimated using emissions factors (Level 1 to 3) and those that are based on empirical measurements, either at Level 4 (source-level) or at Level 5 (reconciliation of source-level inventories (Level 4) with independent site-level measurements).