Detecting methane leaks - a significant contributor to global warming - is becoming increasingly important in the fight against climate change and reducing greenhouse gas emissions. Researchers are harnessing the power of cutting-edge satellite technology to monitor these leaks from space. Methane is a powerful greenhouse gas and the second largest climate-warmer after carbon dioxide. Although a ton of methane only lasts about 10 years in the atmosphere, over a century it retains 30 times as much heat as a ton of carbon dioxide. This means that methane is a powerful player in warming the planet.
The Tropomi instrument on the Copernicus Sentinel-5P satellite is the only satellite instrument to map global methane concentrations on a daily basis. Today, researchers at SRON, the Netherlands space research institute, unveiled a new algorithm that uses machine learning to automatically discover methane super-emission plumes in Sentinel-5P data. Source: ESA/SRON
But here’s the good news: Because methane doesn’t stick around for as long as carbon dioxide does, it gives us an opportunity to take relatively quick climate action. If we reduce methane emissions, we could actually see a significant decline in global methane levels in just a decade. This in turn helps mitigate the increase in the greenhouse effect.
This image shows one of the methane super emission plumes detected by Copernicus Sentinel-5P in a detection group at an oil extraction site in Libya on July 26, 2021. The GHGSat satellite, observing targets detected by Tropomi in the area, detected emissions from an unlit flare. Image source: ESA
Now, let's talk about "super emitters". Methane emitters are any source of methane, including natural processes like wetlands or human activities like agriculture, but methane super emitters release disproportionately large amounts of methane compared to other emitters.
These super emitters are often found in industrial facilities, such as oil and gas operations, coal mines, and even landfills, where equipment or infrastructure problems can lead to large methane leaks. These emission sources are the "low-hanging fruit" in our quest to reduce emissions. Fixing these super emitters doesn’t require complex or expensive solutions. In many cases, relatively simple repairs can deliver significant climate benefits.
However, we face a challenge: we first need to identify these super emitters. In this way, we can be targeted and make a difference in the fight against climate change.
The Tropomi instrument on board the Copernicus Sentinel-5P satellite is the only satellite instrument that maps global methane concentrations on a daily basis.
The satellite measures methane by observing the Earth's atmosphere, specifically in the shortwave infrared band. These bands are like a unique fingerprint of methane, allowing Sentinel-5P to detect the presence of methane with great accuracy.
This rich data plays a vital role in our understanding and response to the climate and environmental consequences of methane emissions, making it an indispensable tool in the fight against climate change.
Researchers at the SRON space institute in the Netherlands have unveiled a new algorithm that uses machine learning to automatically discover methane super-emission plumes in Sentinel-5P data.
It also automatically calculates relevant emissions based on measured concentrations and contemporaneous wind speeds.
This image shows layered satellite observations of methane leaks in Algeria on January 4, 2020. Near the Hassi Messaoud oil/gas field in Algeria, researchers from the Netherlands' SRON space institute discovered a leaking facility emitting methane for six consecutive days. On January 4, 2020, Sentinel-5P detected a methane plume over Algeria, extending more than 200 kilometers northeast.
The team used Sentinel-2 images to zoom in on the source of the methane plume and pinpoint the exact location of the leak as an oil/gas well, while Sentinel-3 showed the leak continued for six days. Image source: SRON/JPL (Data: Contains modified Copernicus Sentinel data (2020), processed by ESA)
SRON's Berend Schuit explains: "Previously, we manually identified the largest emitters, but it was still difficult to search among millions of Tropomi pixels. Methane plumes often covered only a few pixels. Now, we automatically get a list of detections from a machine learning model every day. We manually check these detections every week The results, to ensure we have confidence in the detection results. The remaining, dozens of methane plumes, we publish online. We pass information on ongoing leaks to other satellites with higher resolution so that they can pinpoint the source of the leak. The United Nations International Methane Emissions Observatory uses this information to work with responsible companies or authorities to find solutions."
One of the co-authors, Bram Maasakkers from SRON, added: "The dozens of methane plumes detected every week by Tropomi really provide a once-in-a-lifetime opportunity to combat global warming. If it is visible from space, it is serious. Now, for the first time, we have a clear picture of the full extent of these super-emissions." In our publication , we describe the 2,974 plumes we discovered in 2021; 45% of these came from oil and gas facilities, but we also saw plumes from urban areas (35%) and coal mines (20%). The impact of anthropogenic emissions we detected on the climate is far greater than the total greenhouse gas emissions in the Netherlands. In many cases, these leaks are easily fixable."
The paper was published today in Atmospheric Chemistry and Physics and can be viewed here:
https://doi.org/10.5194/acp-23-9071-2023
A three-level approach to methane detection
Detection of methane emissions typically relies on Copernicus Sentinel-5P. Only recently have scientists begun monitoring methane emissions from space using a combination of data from multiple satellites, including the combined capabilities of the Copernicus Sentinel-5P and Sentinel-2 satellites.
These high-tech space-based tools work together to monitor and assess methane emissions globally, allowing researchers to not only detect the presence of methane but also accurately locate and quantify emissions.
Sentinel-5P, which covers the globe every day, is known for its high-precision methane measurements and can detect methane leaks anywhere on Earth. However, there is a problem. The spatial resolution is relatively low, only 7 × 5.5 kilometers. This means it can identify the presence of methane but cannot pinpoint its source.
The Sentinel-2 satellite, on the other hand, is equipped with multi-band instruments that are not designed to observe methane concentrations but can identify the precise location of major methane leaks (emitting more than one ton per hour) with a resolution of up to 20 meters.
So what about the Sentinel-3 mission? The satellites are equipped with multiband radiometers that can observe shortwave infrared bands that are sensitive to methane concentrations. These satellites provide daily global coverage with a ground pixel resolution of 500 meters.
In a recent paper published in Remote Sensing of Environment, SRON researchers found that the Sentinel-3 satellite can obtain methane enhancement values from its shortwave infrared band measurements. Impressively, it has been able to detect maximum methane leaks of at least 10 tons per hour every day, depending on factors such as location and wind conditions. This puts it in a unique position to identify and monitor methane leaks.