Where the data comes from
Every plume comes from the Methane Alert and Response System (MARS) run by UNEP's International Methane Emissions Observatory (IMEO). MARS combines detections from public and commercial satellites (NASA EMIT, ESA Sentinel-2, Sentinel-5P/TROPOMI and Sentinel-3, Landsat, PRISMA, EnMAP, VIIRS, Planet Tanager and GOES), estimates each plume's emission rate, and groups repeat detections into "sources", or sites.
We sync UNEP's official dataset every day. It currently holds 30,000 plumes at 4,175 sites in 96 countries, with detections through 1 Sep 2026.
What an emission rate means
The rate (kilograms of methane per hour) is a snapshot of the moment the satellite passed, with the uncertainty UNEP publishes. It is not an annual total. A leak can last minutes or years, which is why we also show how often each site has been seen and UNEP's persistency category (persistent, frequent, sporadic).
Satellites only see large leaks (usually hundreds of kg/h or more), can't see through clouds, and revisit some regions more often than others. A country with more detected plumes does not necessarily emit more in total.
How we attribute an operator
UNEP does not publish who operates each site. We estimate it by combining, in order:
- A site registry: attributions researched site by site, with their sources.
- Operator-tagged assets near the plume: facilities from the US EPA GHGRP, oil and gas infrastructure inventories, and OpenStreetMap, filtered by type (a landfill doesn't explain a plume over a well pad).
- Who runs the sector in that region: for example, where a state company operates nearly every field in a country or province.
Every attribution carries a confidence level:
- Confirmed confirmed by a document or by the operator itself.
- Strong evidence an asset of that operator within 1 km, or several independent sources agree.
- Plausible the company dominates the sector in that region, or has an asset 1–3 km away. Most attributions are at this level.
- Weak (context only) context only: we never name an operator publicly at this level.
An attribution is not an accusation. It is our best estimate, with the evidence shown so anyone can check it.
How accurate it is
In October 2026 we evaluated the system on a sample of 50 sites (43 with an operator known from independent sources). It identified the right operator in 91% of cases, found a contact route at the right organisation in 90%, and a relevant authority in 84%. The evaluation code is open source.
Outreach and leak status
The "notified" and "operator responded" fields come from UNEP. The Methane Leaks outreach log is filled in by our users when they write to an operator; it is self-reported.
Corrections and right of reply
Every site, company and plume page has a correction form. Operators can reply to or correct an attribution at any time; we review every message within a week and update the page when the evidence supports it. You can also write to info@methaneleaks.com.
License and how to cite us
UNEP publishes the data under CC BY-NC-SA 4.0, and our derived pages are shared under the same license. Cite as: "Data: UNEP IMEO MARS; attribution: Methane Leaks (methaneleaks.com)".
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