By Toby McIntosh
The UN Environment Programme has documented 41 cases where notifying countries about methane emissions detected by satellites has resulted in ending the emissions.
The mitigation successes over three years are compiled in a new report and new one-page summaries briefly describe the problems found plus the remedial actions.
The same report also lists the 50 largest methane emission sources detected by satellites. UNEP in 2023 established a large database under a project is known as MARS, the acronym for the Methane Alert and Response System, run by the International Methane Emissions Observatory (IMEO) at UNEP.
The April 23 press release heralds a “growing number of mitigation cases.” It says: “By making the biggest sources public, IMEO is scaling methane transparency to accelerate action. When a source is clearly and publicly identified, it becomes easier to act on and harder to ignore.”
Clearly and Publicly?
There are some caveats to UNEP’s claims about transparency.
- UNEP does not name the responsible parties.
- UNEP hasn’t published summaries for about one-third of its mitigation successes.
- UNEP does not disclose how often mitigation occurs once governments are notified, but it appears to be about 1 percent.
- UNEP does not disclose notifications to governments about emissions.
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Response Rate to UNEP Growing
UNEP has shown an increased response rate to its notifications. However, the reported response rate is around 12 percent.
In 2024, UNEP notified governments of 1,200 major methane emissions, but got only 15 replies, a one percent response rate, according a UNEP report.
This was called “a stark statistic” in a 2025 UNEP report which showed improvement. “In less than a year, this rate has increased to more than 12 per cent.”
“This shift has been driven in part by increased engagement from IMEO and partners,” according to the report. “IMEO’s network of focal points is growing, with 25 countries having nominated individuals to receive MARS notifications and another six focal points nominated at the subnational level.”
“Country response rates vary, with some countries exceeding 80 per cent, demonstrating strong engagement and effective follow-through,” the latest report states. “Others — including countries with many emission sources — are making progress as they scale their response capacity,” according to the report.
“Response is a critical step towards methane mitigation, as it requires the investigation of a MARS-detected emission source,” explained the latest UNEP report. “Responses may be submitted by governments or operators.”
“The growing body of confirmed mitigation action underscores the concrete progress possible when governments and companies engage with MARS,” according to the 2025 MARS annual report, which discussed mitigation cases and some other positive signs.
The report said “there remains a significant opportunity— and a critical need—for further action.” And further, “While a 12 per cent response rate demonstrates rapid growth, the reality is that 88 per cent of methane-emitting sources detected via MARS have not received any response—amounting to over 900 individual sources around the world.”
“The growing body of confirmed mitigation action underscores the concrete progress possible when governments and companies engage with MARS,” according to the annual MARs report for 2025.
Mitigation Rate About One Percent
UNEP’s new inventory indicates an increase in actions to end the emissions following notifications sent by UNEP to governments, known as “alerts.”
A rising number of mitigation actions is shown: one in 2023, 11 in 2024, 23 in 2025 and six so far in 2026.
The latest report says the places where mitigation took place “are estimated to have released 1,200,000 tonnes of methane, an amount that has the same climate impact as the annual emissions of 24 million gasoline-powered cars.” The report does not indicate what period was measured.
The report does not include other benchmarks: the rate of mitigation per notification or the rate of mitigation per response. These can be calculated from data is other UNEP reports.
There were 4,163 new methane plumes detected in 2025, according to UNEP data. UNEP sent out 2,203 notifications in 2025. So notifications were sent 53 percent of time.
With a response rate of 12 percent in 2025, there were about 240 responses.
So with 240 responses in 2025 and 23 mitigation actions, the mitigation rate per response is about 9 percent.
The percentage of mitigation actions per notifications in 2025 (23 per 2,203) is 1 percent.
The response rate to notifications sent to major emitters seems roughly the same, according to information in the latest report.
The top 50 emitters list indicates in one column indicating that notifications were sent concerning 17 of the 50, or about one-third of the time.
Of these, the “Y” and “N” indictors show that “feedback” was “received” in seven cases, so a response rate of about 14 percent.
UNEP has said that its priority focus was on emissions from oil and gas facilities. The latest report seems to verify that, indicating no notifications were sent out about emissions from coal mines or landfills. The top 50 list also includes 22 coal sites and 11 waste sites.
“When the world can see exactly where the biggest methane sources are and whether governments are responding, it creates a powerful lever for progress,” according to the MARS website.
The top 50 list and a map showing the locations do not link to other MARS data. However, the MARS interactive map is here (click away the top 50 box), which includes emissions data The dataset is downloadable here.
Note: Although UNEP reports cite a 12 percent response rate in 2025 the MARS database contains a spreadsheet with slightly different numbers that show a rate of 14 percent (1,234 notifications and 172 replies). Download response rate data. The United States, with the highest number of notifications (369) has only nine recorded responses.
No Names Policy
UNEP does not identify the responsible party by name in its database or the mitigation reports.
Instead, it provides a country location and the longitude and attitude coordinates. The source is generically described, both by “sector,” such as “thermal coal,” and “potential source type,” such as “venting shaft.” Neither the name the facility nor the owner is provided.
For example, in the report on the most recent mitigation action, in Kazakhstan, UNEP says, “The operator transferred the gas flow from the affected pipeline to another pipeline, stopping the emissions.”
Reporting on Individuals Cases Still Incomplete
UNEP has reported before on some of its mitigation successes, but as part of larger reports, not in separate reports.
Now, each mitigation case is summarized in a one page documents, found on a Case Studies page.
However, not all of these summaries are yet available.
Fifteen of the 41, from both 2024 and 2025, are annotated with “Available shortly.”
No Disclosure About Notification Documents
UNEP notifies governments about emissions, but it will not disclose documents about its notifications or communications with the countries. Eye on Global Transparency made such requests and they were rejected.
UNEP Executive Director Inger Andersen, in response to a request by EYE, and concurring with the secret findings of a secret UNEP panel, said UNEP’s Access to Information Policy covers only “environmental information.” (See EYE report, March 7, 2025)
She thus denied access to UNEP notifications sent to governments.
The outcome is at odds with a pro-transparency decision on the same subject made in July 2024. Back then, EYE requested one document, which (after an appeal) was provided: a UNEP communication sent to Kazakhstan about a major methane emission. (See EYE article, July 10, 2024.)
But when EYE subsequently asked for the same communications sent to Kazakhstan over a period of 15 months, UNEP refused. EYE appealed and Andersen denied access.
UNEP’s record also casts doubt on whether information will ever be available about efforts to achieve mitigation that are not successful,
Another New Report Focuses on Landfills
Separately, the UCLA’s STOP Methane Project, run by the Emmett Institute at UCLA Law, on April 22 identified 25 waste facilities in 18 countries responsible for the most acute hourly methane emissions.
The report identifies the likely operators and links to maps and observations data by CarbonMapper.
Correlating the UNEP and UCLA reports on emissions is difficult because of variations in methodology and the satellite measurements.
Of the 11 landfill sites on UNEP’s top 50 list only 5 of those also appear on the UCLA list of 25 landfill emitters. The three largest UNEP landfill sites appear on the UCLA list.
The landfill on the top of UNEP’s chart, in Chile (at coordinates -32.95405, -70.79594 says UNEP) is shown as emitting 102,667 metric tonnes.
The same landfill is fifth on the UCLA list, with KDM Tratamiento listed as the “Potentially Responsible Operator” and an emission rate of 5.5 tonnes per hour. See link to map and more data.
