Data dictionary: the world's top 50 methane emitters
Easily interpret the world's top 50 methane emitters list.
IMEO’s list of the world's top 50 methane emitters identifies the largest methane sources globally using data from the Methane Alert and Response System (MARS). The list is designed to support and prioritize mitigation efforts where emission reductions can have the greatest impact.
The list is generated through queries to Eye on Methane // GLOBAL. It ranks sources by emission flux rate, selecting the top 50 most well-known persistent sources—those with persistence uncertainty ≤ 0.15 and sustained activity (persistency ≥ 0.4). The list is updated monthly.
For a detailed explanation of the underlying metrics, please refer to the UNEP IMEO Technical Documentation for Methane Satellite Detection and Quantification.
The data may not be used for any commercial purposes and is shared under a Creative Commons BY-NC-SA 4.0 (“Attribution-NonCommercial-ShareAlike 4.0 International") license. This means that you are free to share and adapt the material, if you credit UNEP’s International Methane Emissions Observatory and indicate whether any changes were made.
Shared information
The information below summarizes the content of the table for the world's top 50 methane emitters (unep_methanedata_topemitter_sources).
| Column name | Definition | Type | Example |
|---|---|---|---|
| Country | Name of the country where the source is located. | String | United States of America |
| Sector | Industry sector of the emission source (e.g., "Oil and Gas", "Waste", "Met Coal", "Thermal Coal", "Thermal and Met Coal" or "Other"). | String | Oil and Gas |
| Potential source type | Category of the infrastructure or piece of equipment identified as the potential origin of the detected plume based on MARS analysts' visual inspection and best guess. If the infrastructure cannot be identified based on the available information, the label includes the suffix "(generic)". | String | Flare |
| Source ID | ID of the source, formatted as {ISO3CD}_S_{number}*. The ID is consistent with the information presented on the map of the Eye on Methane data platform. | String | ALG_S_002 |
| Latitude | Latitude coordinate of the source location (north-south direction) in decimal degrees (WGS84), rounded to five decimal places. | Float | 12.34567 |
| Longitude | Longitude coordinate of the source location (east-west direction) in decimal degrees (WGS84), rounded to five decimal places. | Float | 12.34567 |
| Number of plumes detected (2024-present) | Number of plumes attributed to this source since 2024 to present. | Integer | 12 |
| Plumes notified (Y/N) | Indicates whether the relevant government or facility operator has been notified of the plume attributed to this source. • “Y”: at least one plume over this source has been notified. • “N”: no plumes on this source have been notified. | String | Y |
| Feedback received (Y/N) | Combined feedback status from both operator and government. • "Y": feedback received from either operator or government (or both). • "N": no feedback received from either operator or government. | String | Y |
| Av. half-year flux rate (t/h) | Mean methane emission rate estimated from all plumes attributed to the source over a rolling six-month period, expressed in metric tons per hour (t/h) and rounded to two decimal places. | Float | 1.23 |
| Av. annual flux rate (t/h) | Mean methane emission rate estimated from all plumes attributed to the source over a rolling 12-month period, expressed in metric tons per hour (t/h) and rounded to two decimal places. | Float | 1.23 |
| Av. annual flux rate std. dev. (t/h) | Standard deviation of the methane emission rate estimated from all plumes attributed to the source over a rolling 12-month period, in metric tons per hour (t/h) and rounded to two decimal places. | Float | 0.12 |
| Date of the last plume detected | Timestamp of the satellite observation in ISO 8601 format** for the last detected plume. | String (datetime) | 2020-01-01T12:00:00a |
| Half-year persistency category | Categorical classification of emission frequency based on half-year persistency. "Undetermined": insufficient observations. “Absent": no emissions detected, persistency is equal to 0. "Sporadic": persistency within the interval (0, 0.2]. "Frequent": persistency within the interval (0.2, 0.8]. "Persistent": persistency larger than 0.80. | String | frequent |
| Half-year emission persistency | Estimate of how often emissions are detected from a specific source over time. Number of times emissions were detected compared to the number of high-quality observations over the last 180 days. Values range between 0 and 1, or null if observations are insufficient. | Float | 0.65 |
| Half-year persistency std. dev. | Standard deviation of the half-year persistency estimate. Values range between 0 and 1, or null if observations are insufficient. | Float | 0.1 |
| Annual persistency category | Categorical classification of emission frequency based on the annual persistency: "Undetermined": insufficient observations. “Absent": no emissions detected, persistency is equal to 0. "Sporadic": persistency within the interval (0, 0.2]. "Frequent": persistency within the interval (0.2, 0.8]. "Persistent": persistency larger than 0.80. | String | Frequent |
| Annual emission persistency | Estimate of how often emissions are detected from a specific source over time. Number of times emissions were detected compared to the number of high-quality observations over the last 365 days. Values range between 0 and 1, or null if observations are insufficient. | Float | 0.65 |
| Annual persistency std. dev. | Standard deviation of the annual persistency estimate. Values range between 0 and 1, or null if observations are insufficient. | Float | 0.1 |
| Estimated half-year CH4 emissions (t) | Estimated total mass of methane emitted over the last six months, derived from the combination of the mean emission rate, the source persistency and hours in a year, expressed in metric tons (t). | Integer | 12345 |
| Estimated annual CH4 emissions (t) | Estimated total annual mass of methane emitted, derived from the combination of the mean emission rate, the source persistency and hours in a year, expressed in metric tons (t). | Integer | 12345 |
Additional considerations
The world's top 50 methane emitters list reflects the largest point‑source emitters identified so far by MARS, based on the most recent six months of observations. The ranking is derived from emission persistence and average emission flux over that period. As both metrics depend on the availability of high‑quality, cloud‑free imagery, the list is subject to seasonal and regional variability in observation conditions.
In some regions, strong seasonal cloud cover can significantly reduce the number of observations for certain sources. Where available data falls below the minimum threshold required to estimate persistence, these sources cannot be included in the ranking—not because they are minor emitters, but because MARS lacks sufficient recent observations to characterize them. Other factors can also influence observation frequency and introduce seasonal effects, including the solar zenith angle, which affects surface radiance and influences the probability of detecting emissions, particularly in offshore and desert areas, and surface type with desert regions typically offering higher observation frequency than vegetated or heterogeneous landscapes.
As a result, the world's top 50 methane emitters list should be interpreted as a representation of major emitters that MARS is currently able to detect, given the most up‑to‑date and seasonally dependent data coverage.