Researchers assessed hundreds of possible methane sources by interpreting data obtained from satellites. They employed measurements from the Copernicus Sentinel-5P mission, focusing on 217 potential emission sites worldwide. Results were consolidated into a list that emphasizes areas with near-constant methane output.
Published in the journal Atmosphere, Chemistry and Physics, the paper concentrates on gradual, long-term emitters of methane. These differ from so-called super-emitters, which typically release very large amounts of methane but do so in intermittent bursts associated with operations such as coal mining, oil and gas extraction, or poorly maintained landfills.
Sentinel-5P is a collaborative effort led by ESA in partnership with the European Commission, the Netherlands Space Office, and industry. It is equipped with the Tropomi instrument, able to map various trace gases including methane. The study draws on an advanced dataset and algorithm developed by the University of Bremen, part of ESA's Climate Change Initiative Greenhouse Gas Project and two ESA Earth System Science Hub efforts known as Methane CAMP and SMART-CH4.
According to Claus Zehner, ESA's Mission Manager for Sentinel-5P, "Sentinel-5P is currently the only satellite that provides the feasibility to detect methane sources on a global scale and on a daily basis."
Investigators collected and analyzed methane data (parts per billion) from 2018 to 2021 to identify persistent emitting spots. A site was considered persistently active if its methane concentrations stayed higher than those in adjacent regions.
One of the authors, Michael Buchwitz, Senior Scientist at the University of Bremen, explained, "The aim was not to identify specific events, where methane is only released for a short period of time. Instead, the aim was to identify sources that emit almost continuously during the four years that were analysed. This includes natural sources such as wetlands, but also coal mining areas or large oil and gas fields."
Wetlands account for the most significant natural source of methane, thanks to microbes in wetland soil that generate high levels of the gas. Two wetlands appear in the top 10 identified by the study: the Sudd in southern Sudan and the Ibera in Argentina.
The Sudd region has long been recognized as a substantial methane hotspot. In 2020, its methane levels rose sharply due to unusually heavy rainfalls and increased water flow from the White Nile. The area extends approximately 500 km north to south and 200 km east to west, covering about 57 000 square km, although seasonal flooding can double its size.
Argentina's Ibera wetlands, located in Corrientes province, is about half the size of the Sudd. It serves as a major freshwater reserve in South America and ranks third among the study's persistent methane sources.
On the human activity side, the largest identified emitter is an oil and gas area along Turkmenistan's western coast. Further oil and gas sources are spread across North America, including the Permian Basin, which straddles Texas and New Mexico. In addition to oil and gas fields, the top 10 list features three coal sites in China's Shanxi province and Russia's Kuznetsk Basin, which is a major coal mining region.
The researchers also noted other anthropogenic emitters, such as landfills, wastewater systems, livestock-related emissions (from cattle, sheep, and goats), manure, rice cultivation, and energy infrastructure. These sources all contribute to continuous methane releases that gradually build up in the atmosphere.
Methane ranks as the second most influential greenhouse gas after carbon dioxide, although it is found naturally in the environment. Its upward trend in atmospheric concentration is a critical factor in rising global temperatures. Measurements from NOAA suggest that methane has nearly tripled from pre-industrial levels, going from roughly 700 parts per billion in the mid-1800s to over 1900 parts per billion today. The Global Methane Budget 2024 indicates a marked increase in anthropogenic methane emissions over the last 20 years.
Methane's warming effect is much stronger than that of carbon dioxide, though it remains in the atmosphere for a shorter period. Across 20 years, each kilogram of methane is more than 80 times more potent in heating the planet than the same mass of carbon dioxide. Curtailing these emissions is therefore widely viewed as a crucial means of slowing climate change.
+ Region - Emissions (MT/yr) Source
+ South Sudan - Sudd 4.5 Wetland
+ Turkmenistan - coast 3.5 Oil and gas
+ Argentina - Ibera 3.3 Wetland
+ China - Liaoning 2.9 Other anthropogenic sources
+ China - Shanxi 1 2.6 Coal
+ China - Shanxi 2 2.6 Coal
+ China - Shanxi 3 2.4 Coal
+ Bangladesh - Dhaka 2.4 Other anthropogenic sources
+ Russia - Kuznetsk Basin 2.4 Coal
+ USA - Permian Delaware 2.2 Oil and gas
Research Report:Automated detection of regions with persistently enhanced methane concentrations using Sentinel-5 Precursor satellite data
Related Links
Sentinel-5P at ESA
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