MARS Frequently Asked Questions

MARS is a data-to-action initiative with the mission to put open, reliable, and actionable data into the hands of individuals who can reduce methane emissions. ​

MARS uses satellites to scan the globe for major emission sources and alerts countries and companies so that they can take methane action and accelerate progress supporting the Paris Agreement and Global Methane Pledge.​

The MARS initiative works in partnership with the Climate and Clean Air Coalition (CCAC) and the International Energy Agency (IEA). After COP 28, the World Bank will also be joining the initiative. MARS also partners with SRON and Kayrros to analyse and process satellite data.

Methane emissions from human sources drive about 30% of today’s global warming. Because methane is a greenhouse gas over 80 times more powerful than carbon dioxide but remains in the atmosphere for far less time, emissions reductions now can deliver immediate climate progress and buy us time to pursue broader decarbonization.​

Reducing methane emissions also carries significant benefits for public health, economic livelihoods and energy security. ​

A report from the International Energy Agency, UNEP, and the Climate and Clean Air Coalition finds that in the fossil fuel sector alone, where reductions are overwhelmingly cost-effective and readily available, targeted action could avert nearly 1 million premature deaths from ozone pollution, 90 million tonnes of crop losses and about 85 billion hours of lost labor from heat exposure by 2050, all while providing roughly USD 260 billion in direct economic benefit.​

MARS brings together four critical components to drive transparency and enable emission reductions: ​

1. Detection of large sources of human-caused methane emissions.​
2. Notification of relevant countries and companies about these detected emissions.​
3. Response from notified stakeholders to address the emissions.​
4. Tracking progress of actions taken to reduce emissions and collaboration to prevent future methane

MARS is the the first global satellite detection and notification system providing actionable data on very large methane emissions around the world.​

MARS plays a unique role by drawing data from nearly a dozen satellite instruments and providing it in an accessible and actionable form. The system leverages UNEP’s global reach across governments, civil society, and the private sector to put this data in the hands of stakeholders who can use it to drive down methane emissions.​

MARS was announced at the COP 27 in November 2022 and began its initial pilot phase in January 2023. The pilot phase presented an opportunity for UNEP’s IMEO to engage with partners, countries, and operators to refine MARS processes and procedures before making data public.​

Now fully operational, the system will work to incorporate new satellites as they come online to refine its ability to deliver actionable data.​

Any questions about MARS data or process should be directed to IMEO@un.org​

MEO uses the existing suite of Earth Observation satellites to detect emissions, trace them to their source, and quantify them across the globe. ​

Data from these satellites is publicly available, though sometimes requires specialized remote sensing expertise to properly interpret. UNEP’s IMEO provides this expertise to the global community to supply actionable data and further the goals of the Global Methane Pledge. ​

More information on satellites used by MARS can be found here.​

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 Earth’s 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 Earth’s 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, 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 (> 1,000 kg methane per hour for current public satellites), it’s also important to address the many smaller sources of methane that in aggregate make up a majority of the world’s methane challenge.​

In some cases, satellite limitations prevent detection of methane across certain parts of the globe. For example, because satellites require sunlight reflected from the Earth’s surface to detect methane emissions, persistently cloudy regions or those with reduced sunlight present barriers to detection of emissions.​

See question and answer above for additional detail on satellite capabilities.​

Additionally, because the project’s focus has been on methane emissions from oil and gas, the current distribution of detected events could reasonably be expected to be seen in oil and gas producing regions and not elsewhere. ​

While the IMEO data platform is in its beta version, the following data is made publicly available after 45-75 days post-detection: ​

• All IMEO-gathered satellite data and related metadata (e.g., visual data), including non-notified data.​
• A filter to indicate if a particular emissions event has been notified at the government level.​

In the future versions of the platform, additional information will be provided that includes:​

• A summary of operator and/or government response(s) to the notification process.​
• A summary description of mitigation efforts and/or plans.​
• Any past or future MARS detections linked to the event location.​

Data is made available after a 45-75 day period for a number of reasons:​

• To allow experts time to ensure proper data quality and assurance so that the data remains reliable and actionable. ​
• To ensure there is time to engage governments and companies on emissions events and identify resources that can identify how to mitigate them. 

MARS combines the capabilities of satellites with a broad view of emissions across a large area with high-resolution satellites that can monitor methane emissions down to a small area on the ground. This enables a “tip-and-cue” approach.​

Regions of Interest (ROIs) are determined through:​

• Averaging observations from lower-resolution satellites like TROPOMI, GOSAT/GOSAT-2, or in the future MethaneSAT, which cover much of the globe on a daily basis to identify “hotspots.” These are regions of higher methane concentrations that indicate emissions from one or more significant sources.​
• Analysis of individual methane plumes detected from a non-targeted, continuously observing satellite instrument such as TROPOMI, Sentinel-2, Landast, or EMIT.​

Once a ROI is determined, UNEP IMEO’s actions will include one or more of the following:​

• Search available high-resolution satellite records for recent emissions from the ROI.​
• Search available high-resolution satellite records for indication of long-term emissions from the ROI.​
• Target high-resolution satellites, such as PRISMA and EnMAP, to look at the ROI to find current emissions.​

After a ROI has been investigated once, MARS utilizes deep learning models to monitor data from continuously observing high-resolution satellites for future emissions from the region.​

Notifications are sent to governments and companies once high-resolution satellites can locate emissions at the facility-level. These notifications may be “batched,” meaning they may contain emissions from one or more facilities over a recent time period.​

Once UNEP’s IMEO has linked a methane emission to a facility via high-resolution satellite data, it is possible to notify stakeholders of that emission. If there are multiple emissions detected within the same region during the same timeframe, they may be “batched” together within a single notification.​

An initial notification is provided via email as quickly as possible after a detection is made. The notification provides preliminary information on the emission, including location, detection time, and the potential facility operator. Over the course of the following week, UNEP’s IMEO continues to analyze the emission and a subsequent notification is sent that includes further detail from this analysis, including potential source and size of the emission, in addition to whether the event is persisting.​

Notifications are always sent to national-level government contacts in the appropriate ministry, as determined by a country’s government. If UNEP’s IMEO is able to link an emitting facility to an operator that is a member of UNEP’s Oil and Gas Methane Partnership 2.0, the notification will also be sent directly to that operator. Otherwise, UNEP’s IMEO will request that the government assist it in notifying the facility operator. ​

UNEP’s IMEO requests that governments quickly acknowledge receipt of the MARS notification. If the notification was not shared directly with an OGMP 2.0 member company, the government will be requested to provide the notification to the relevant operator.  ​

UNEP’s IMEO will keep government contacts informed of any communications with operators as well as the final outcomes of any mitigation processes put in place.  Further, UNEP’s IMEO will share any additional satellite data localized to the notified site(s) that becomes available in the 45-75 days post notification prior to public release of data. ​

UNEP IMEO requests that operators first quickly acknowledge receipt of a MARS notification and subsequently requests return of an initial feedback form provided. This form seeks to gain any information that is readily available to the operator within 5 days of receipt of the MARS notification (e.g., facility type, if the operator knows of an existing ongoing operation potentially responsible for observed emissions).  ​

After providing initial feedback, the operator is requested to provide more detailed final feedback no later than 45 days post notification. Further, UNEP will share any additional satellite data localized to the notified site(s) that becomes available in the 45-75 days post notification prior to public release of data. At any time during the process, operators are encouraged to communicate with UNEP regarding the notification, and UNEP and its partners stand ready to aid with mitigation efforts as requested.  ​

Not necessarily. Methane emissions are also detected from satellites that do not have a high enough resolution to identify the facility responsible. ​

Plumes from ESA’s Sentinel 5-P TROPOMI instrument, which has a coarse pixel-size, cannot always be attributable to the facility-scale. MARS cannot notify individual operators of TROPOMI-detected plumes unless UNEP IMEO is also able to co-locate a detection with a high-resolution point source imager (e.g., PRISMA, Sentinel-2; see Table).  Consequently, most TROPOMI-detected plumes cannot be used in the context of a notification. ​

Most MARS notifications are based on detections from high-resolution point source imagers. During the MARS pilot, MARS partners decided to establish initial contact with relevant governments prior to sharing a notification. When this contact could not be established, the notification was withheld pending first contact. Additionally, during the pilot phase, notifications were not sent to certain countries experiencing ongoing international conflict.   Following the full launch of MARS, partners will seek to share notifications with all relevant governments. ​