Frequently Asked Questions (FAQ)
What is Carbon Mapper?
How is Carbon Mapper’s approach different from past or current initiatives?
How will Carbon Mapper data actually translate to emission reductions?
How is the Carbon Mapper program different from other methane monitoring satellites?
In addition to tracking methane emissions, Carbon Mapper will also monitor fossil fuel CO2 emissions and deliver 25 other environmental indicators useful for ecosystem management and incident response on land and at sea. This provides significant flexibility that supports commercial services sufficient to build out the fully operational constellation while sustaining Carbon Mapper’s public good mission of delivering transparent methane and CO2 emissions data.
Carbon Mapper will monitor priority regions around the world to detect, pinpoint and quantify methane and CO2 emissions from individual facilities including highly intermittent activity. Our system’s agility and flexible targeting also allows for rapid follow-up for hotspots identified by wider-area mapping satellites such as the European Sentinels and EDF’s MethaneSAT. Carbon Mapper is intended to serve as a major tier of an emerging global system of observing systems and complement the other satellite programs.
WHY FOCUS ON METHANE?
Methane (CH4) is a powerful greenhouse gas—second only to carbon dioxide as a climate-forcing agent resulting from human (anthropogenic) activity. The growth rate of methane in the atmosphere is due to a complex combination of natural and anthropogenic emissions and natural removal processes. The exact causes for observed changes in the methane growth rate over time remain uncertain due to incomplete data. Methane emissions and their causes at local scales remain particularly uncertain. Additionally, methane is also being increasingly prioritized by some companies and governments for near-term climate action given its relatively short atmospheric lifetime and the potential for rapid, focused mitigation that can complement economy-wide efforts to reduce carbon dioxide emissions. Methane is also a precursor for tropospheric ozone and is strongly linked with co-emitted reactive trace gases targeted by air quality and public health policies. Finally, methane vented to the atmosphere from leaks in natural gas infrastructure – if not promptly detected and repaired – can result in costly product loss and (in sufficiently large quantities) a combustion hazard. All of the above factors motivate the need for increasing the availability of methane data across a broad range of scales.
WHAT ABOUT OTHER GASES?
Ammonia and carbon dioxide are just some of the gases that can be co-emitted with methane from some landfills, dairies, oil fields and power plants. The data presented here is limited to methane given our research focus on greenhouse gases. Some state and local agencies such as the California Air Resources Board (CARB) and Air Quality Management Districts monitor air quality and criteria pollutants. CARB and the US Environmental Protection Agency also maintain databases of self-reported emissions from large facilities in selected sectors.
WHAT’S A METHANE "PLUME"?
WHAT IS THE DIFFERENCE BETWEEN A PLUME AND A SOURCE?
A methane source is a condensed surface feature or infrastructure component (typically < 10 meters across) that emits plumes of concentrated methane. In cases where we observe multiple instances of a plume at a given location we combine our individual plume emission estimates to derive a source-average emission rate, including the impacts of intermittency.
WHAT’S THE DIFFERENCE BETWEEN METHANE GAS CONCENTRATIONS, ENHANCEMENTS AND EMISSIONS?
The relative amount of methane in a given volume of air is often represented as the methane concentration (or more accurately, the dry air mole fraction). For example, the current global average concentration of near-surface atmospheric methane on earth is about 2 parts per million (ppm).
When methane concentrations in a localized volume of air are measurably higher than average background concentrations (methane in less polluted nearby air) we refer to that increase as the methane enhancement. For example, in the presence of a steady breeze, if a methane emitter results in localized concentrations of 10 ppm and the cleaner upwind air has an average background concentration of 2 ppm we would say that local enhancement is 10−2 ppm = 8 ppm. Methane enhancements can also be represented by absolute mass units; for example, a localized enhancement might contain several kilograms of methane.
An emission is the rate at which methane is generated by a source. For example, the emission rate for a venting gas pipeline compressor station might be 100 kilograms per hour (kg/hr) of methane, equivalent to about 5400 standard cubic feet per hour (scfh) of natural gas.
WHAT ARE THE DIFFERENT TYPES OF METHANE EMITTERS?
An emitter (or emission source) refers to the physical or biological activity that generates methane gas. There are two basic categories of methane emitters: point sources and area sources.
We define a point source to be a condensed surface feature or infrastructure component (typically < 10 meters across) that emits plumes of highly concentrated methane that’s above the detection limit of our remote sensing technology. Examples of point sources include individual pieces of natural gas infrastructure, oil wells, refineries, gas-capture systems in landfills, waste water treatment plants, manure management systems at large dairies and wildfires. Point sources include a relatively small number of so-called “super-emitters” with methane emissions >> 10 kg/hour and a large number of much smaller emitters. The majority of methane plumes in this data portal are super-emitters.
An area source is typically distributed over a large area (typically 1–100 km across) that releases methane in a more diffuse fashion such as anaerobic decomposition occurring with rice cultivation and natural wetlands or enteric fermentation from livestock.
Sometimes the cumulative effect of a large number of low-emitting point sources can manifest as an area source—for example, cities can appear as a large area source due to the combined impact of millions of small natural gas leaks in distribution infrastructure and even downstream of meters in homes and businesses. While our research program includes observations and analysis of methane across multiple scales the data products in this portal are currently primarily limited to local scale methane plumes.
HOW STEADY OR PERSISTENT ARE METHANE EMISSIONS?
Depending on the underlying mechanisms, methane emissions can vary by hour, season or even years. For example, methane emissions from oil and gas infrastructure, refineries, power plants and manure management at large dairies are often highly intermittent on time scales of hours due to normal operations such as periodic venting or flaring, but a malfunction or leak can result in emissions that persist for years. In other cases, methane emissions can sometimes vary strongly from season to season as a function of environmental conditions that affect methane producing bacteria (landfills) or by demand (residential natural gas consumption). Over time spans of years, we may see trends in emissions in response to mitigation (reduction) or new activity (growth).
WHAT ARE SOME GENERAL FINDINGS FROM REGIONAL METHANE SURVEYS?
- High emission point source activity is common and occurs in multiple economic sectors including fossil fuel production and use, waste management and agriculture, with significant regional variations. In many cases, these high emission point sources contribute up to 20-50% of regional total methane emissions.
- Many methane point sources are highly intermittent while others are persistent – the average source persistence or frequency is about 25% for most regions.
- Frequent measurements over large areas can help separate persistent activity (including leaks) from more intermittent activity (including periodic planned maintenance events and a mix of normal and anomalous venting).
- Sustained, high resolution remote sensing of methane plumes can pinpoint emissions sources and identify specific equipment for efficient follow up by facility operators and regulators.
- Accurate quantification of regional methane budgets and inventories benefits from tiered observing systems that apply multiple measurements from different vantage points (e.g., land, air and space) to provide a complete picture of the different types of emitters, including strong point sources and wider area sources.
ARE FACILITY OPERATORS USING THE DATA TO REPAIR LEAKS?
We have research collaborations with facility operators for many locations where we’ve detected methane point sources. In those cases, we shared our methane image data and source coordinates and the operators responded with ground based follow-up measurements to verify and/or further pinpoint the locations. Some of those follow-up efforts exposed malfunctioning hardware or leaks that the operator was able to repair. Examples include natural gas infrastructure in cities such as leaking bypass valves at compressor stations and low-pressure distribution pipelines. In those cases the relevant gas utilities confirmed and repaired the leaks. We have also shared data over the course of several years with operators of large municipal landfills in California who used it to guide improvements in their gas capture systems. Carbon Mapper will continue to share data with operators as the program grows.
WHY DO LIVESTOCK PRODUCE METHANE?
There are two main factors that cause cows and other ruminants to emit methane: enteric fermentation and manure management. Enteric fermentation is a part of the digestive process for cows which causes methane to be expelled from the animal from the front end (burping). On average, roughly half of methane emissions from livestock come from enteric fermentation. The remaining livestock methane emissions are due to manure management. The majority of methane data in this portal attributed to livestock is primarily associated with a particular class of manure management: anaerobic “lagoons” that store animal waste/manure. Hence, the majority of livestock methane emissions are not detected with these point source measurement methods.
ARE ALL TYPES OF LIVESTOCK METHANE EMISSIONS SHOWN ON THE DATA PORAL?
No, only a subset. The methane point source data includes manure management sources and specifically from “wet management” techniques. Enteric fermentation manifests as an area source best quantified with other methods and is not included in the current version of this web site.
WHAT AM I SEEING WITH THE CARBON MAPPER DATA PORTAL?
- The current focus of the Carbon Mapper data portal is individual high emission methane point sources. Specifically, the portal provides methane plume imagery with emission rates and uncertainties from strong point sources as observed from NASA’s next generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and ASU’s Global Airborne Observatory (GAO) airborne platforms. These systems have near-identical capabilities and serve as prototypes for future sustained global monitoring by our Carbon Mapper satellite constellation.
- The plume concentration maps shown here are currently available at spatial resolutions ranging from 3 to 8 meters (depending on aircraft altitude), allowing for precise attribution to individual emission sources.
- The data shown here was collected from airborne campaigns starting in 2016 and as of summer 2021 are continuing to expand to cover other regions. To date, airborne surveys have quantified point source emissions in California, Texas, New Mexico, Colorado, Utah, Louisiana, the Gulf of Mexico, and Pennsylvania (with more to come!).
If you have specific questions regarding the data portal that are not addressed in this FAQ, please email email@example.com.
CAN I DOWNLOAD THE DATA? DOES CARBON MAPPER CHARGE FOR ITS DATA?
As of October 2021, data can be downloaded for individual methane point sources on the Carbon Mapper data portal.
Interested users can bulk download Carbon Mapper data, including select plume emissions lists and plume source lists, through the following Digital Object Identifier (DOI) links. Please use the appropriate citation when referencing a given data product in a report or paper.
- California 2016-2017 plume imagery (GeoTIFFs): https://doi.org/10.3334/ORNLDAAC/1727
- California 2016-2017 plume list (CSV), source list (CSV): https://doi.org/10.1038/s41586-019-1720-3 (Go to Supplementary Information)
- Permian Basin 2019 plume imagery (GeoTIFFs): https://doi.org/10.5281/zenodo.5610307
- Permian Basin 2019 plume list (XLSX), source list (XLSX): https://doi.org/10.1021/acs.estlett.1c00173 (Go to Supporting Information)
- All airborne plume imagery (CA, LA, PA, NM, TX, UT) July 2020-August 2021 (GeoTIFFs) and plume emissions lists (XLS): https://doi.org/10.5281/zenodo.5606120
- All airborne plume imagery (AL, CA, CO, FL, GA, LA, NM, NV, PA, TX, UT) July 2020-May 2022 (GeoTIFFs), plume emissions, and source lists (XLS): https://doi.org/10.5281/zenodo.7072824
HOW SHOULD I REFERENCE THE CARBON MAPPER DATA IN JOURNAL PAPERS AND REPORTS?
The following journal papers and reports describe the methods used to generate the various data sets presented here. Please use the appropriate citation when referencing a given data product in a report or paper.
Multi-basin analysis: San Joaquin, Permian, Uinta, Denver-Julesburg, Marcellus (Data from 2020-2021)
Cusworth, D. H., Thorpe, A. K., Ayasse, A. K., Stepp, D., Heckler, J., Asner, G. P., Miller, C. E., Chapman, J. W., Eastwood, M. L., Green, R. O., Hmiel, B., Lyon, D., & Duren, R. M. (2022). Strong methane point sources contribute a disproportionate fraction of total emissions across multiple basins in the U.S. PNAS. https://www.pnas.org/doi/10.1073/pnas.2202338119
Gulf of Mexico offshore platforms (Data from 2021)
Ayasse, A. K., Thorpe, A. K., Cusworth, D. H., Kort, E. A., Negron, A. G., Heckler, J., Asner, G., & Duren, R. M. (2022). Methane remote sensing and emission quantification of offshore shallow water oil and gas platforms in the Gulf of Mexico. Environmental Research Letters, 17(8), 084039. https://doi.org/10.1088/1748-9326/ac8566
Permian point-source data (Data from 2019)
Cusworth, D. H., Duren, R. M., Thorpe, A. K., Olson-Duvall, W., Heckler, J., Chapman, J. W., Eastwood, M. L., Helmlinger, M. C., Green, R. O., Asner, G. P., Dennison, P. E., & Miller, C. E. (2021). Intermittency of large methane emitters in the Permian Basin. Environmental Science & Technology Letters, 8(7), 567–573. https://doi.org/10.1021/acs.estlett.1c00173
California methane point-source data (Data from 2016-2017)
Duren, R. M., Thorpe, A. K., Foster, K. T., Rafiq, T., Hopkins, F. M., Yadav, V., Bue, B. D., Thompson, D. R., Conley, S., Colombi, N. K., Frankenberg, C., McCubbin, I. B., Eastwood, M. L., Falk, M., Herner, J. D., Croes, B. E., Green, R. O., & Miller, C. E. (2019). California’s methane super-emitters. Nature, 575(7781), 180–184. https://doi.org/10.1038/s41586-019-1720-3
Duren, R., Thorpe, A., & McCubbin, I. (2020). The California Methane Survey Final Report, CEC-500-2020-047. https://ww2.energy.ca.gov/2020publications/CEC-500-2020-047/CEC-500-2020-047.pdf
IS THIS REAL-TIME DATA?
While the AVIRIS-NG and GAO airborne platforms have onboard real-time methane detection capability, there are several confounding factors that require subsequent data processing and quality control review to validate, pinpoint and quantify emission sources. That process currently requires a minimum of several weeks to complete following each overflight. Going forward, our objective is to release methane and CO2 emissions data within 90 days of each overflight. We do offer lower-latency data products (typically available within a few days of each overflight) to collaborating research partners however that’s typically not quantitative and subject to revision following full processing.
WHAT MEASUREMENT SYSTEMS WERE USED TO PRODUCE THESE DATA SETS?
Most of the data shown here (e.g.,methane plumes detected at individual facilities) were produced from the AVIRIS-NG and GAO aircraft. In selected areas such as southern California and the Permian Basin we also show some examples of regional scale methane maps derived from a variety of surface and satellite observing systems. See the info icons for each map layer for specific information. By comparing very high resolution data for individual methane point sources with wide area regional emission maps we can develop broader, multi-scale awareness of emissions.
WHY DO SOME AREAS SHOW MORE METHANE SOURCES THAN OTHERS?
DOES THE PRESENCE OF A METHANE POINT SOURCE INDICATE A MALFUNCTION?
Not necessarily. Some methane emissions (often referred to as “process emissions”) are expected and to some extent are already accounted for in inventories and reporting systems; for example, incomplete combustion during gas flaring, venting from vapor relief valves on gas storage tanks, small losses from compressors or area source emissions from landfills and dairies. Examples of malfunctions include persistent leakage due to faulty seals or valves in gas infrastructure, unlit flares, or damage to a gas capture system at a landfill or dairy. The degree of intermittency or frequency of an emission source can provide an important clue about whether a source is an expected process or a malfunction.
DOES A VERY INTENSE METHANE PLUME (STRONG ENHANCEMENT) MEAN THERE’S A LARGE METHANE SOURCE NEARBY?
Not necessarily. The magnitude of a localized atmospheric enhancement depends on both the emission rate and the degree of local ventilation. Wind speed is usually the biggest factor in ventilation but other atmospheric conditions and local terrain can also play a role, in some cases resulting in “pooling” of methane gas leading to large enhancements near a relatively small emitter. For these reasons, when estimating the emissions from a given source we account for both the methane enhancement and atmospheric factors like wind speed.
WHY DO SOME OF THE OBSERVATION METHANE PLUME AND RGB IMAGERY HAVE BLACK AREAS ON THEIR EDGES?
These indicate the edge of a flight-line acquired with the airborne imaging spectrometer which has a finite swath width (field of view). We usually plan our flights with 20% line overlap but sometimes we detect a plume at the edge of a mapping area or the wind changes between adjacent lines so that the plume is visible in one line but not the adjacent line, resulting in “clipping”.
I SEE SOME FLUX VALUES GIVEN AS NOT AVAILABLE OR TBD, WHAT DOES THAT MEAN?
The value is given as “not available” when the algorithm used to estimate emission rate produced a low-confidence result due to plume shape, surface artifacts and/or issues with wind speed data.
I am an operator who would like to report mitigation actions for a methane event in your Data Portal; who should I contact? How do I submit a correction or response to one of the reported emissions on your website?
Please send an email to firstname.lastname@example.org. Please note that information submitted to Carbon Mapper may be shared publicly and we cannot guarantee confidentiality.