The emissions were primarily detected over the largest oil and gas basins in the world. Of the six major oil and gas producing countries where ultra-emitters were observed Turkmenistan ranked highest with 1.3 megatons of methane emitted annually. It was followed by Russia, the United States (excluding the Permian Basin), Iran, Kazakhstan, and Algeria.
The report evaluated the societal costs by incorporating the valuation from the CCAC and UNEP Global Methane Assessment, which assigns a value of $4400 per ton of methane, accounting for the impacts of methane on climate and surface ozone, both of which affect human health, labor productivity, crop yields, and other climate-related impacts. It found that controlling high methane emitters would have net benefits of approximately $6 billion for Turkmenistan, $4 billion for Russia, $1.6 billion for the US, $1.2 billion for Iran, and $400 million each for mitigation in Kazakhstan and Algeria.
In terms of net climate benefits, eliminating methane emissions from ultra-emitters would lead to 0.005° ± 0.002°C of avoided warming over the next one to three decades. Though small, this is roughly the equivalent of the total influence from all emissions since 2005 from Australia or the Netherlands, or the same as removing of 20 million vehicles from the road for 1 year.
The avoided warming would prevent up to 1600 premature deaths annually due to heat exposure and up to 1.3 billion hours of labor productivity lost annually from exposure to heat and humidity, with the latter valued at approximately $200 million per year.
The study was carried out by French and U.S. scientists and led by the Laboratoire des Sciences du Climat et de l’Environnement (LSCE, France). They performed a systematic analysis of thousands of images produced daily by the European Space Agency (ESA) satellite mission Sentinel-5P to estimate the amount of methane released into the atmosphere from oil and gas production.
The detection limit of the Sentinel-5P instrument means it can spot only very large releases (often larger than 25 tons of methane per hour). The relatively small number of release events observed represent billions of dollars in subsequent costs, including the amount of natural gas lost and climate and air pollution-related damages.
“To our knowledge, this is the first worldwide study to estimate the amount of methane released into the atmosphere by maintenance operations and accidental releases,” said Thomas Lauvaux, CNRS research scientist of the French Make Our Planet Great Again program at LSCE. “Unreported ultra-emitters explain in part the under-estimation in official reported oil and gas emissions by countries as documented by previous studies. The atmospheric monitoring approach enabled by recent satellite missions provides a unique perspective on oil and gas activities, and the potential to mitigate these large releases of methane.”
Thomas Lauvaux and Clément Giron, a data scientist at Kayrros Inc., used high resolution atmospheric modelling and machine learning algorithms to detect and to quantify hundreds of methane plumes. They then aggregated their emissions estimates at national scale to evaluate the contribution of ultra-emitters to national reported emissions. To translate their results into a cost-benefit analysis, Dr. Shindell performed climate model simulations to quantify the additional contribution to climate change and examined several analyses of oil and gas sector mitigation costs.
Earlier studies have shown that large emitters were frequently observed across shale gas basins, but the intensity and frequency of these emitters remained unknown. Lauvaux noted however, that the vast majority of unreported leaks and deliberate releases remain invisible to current satellite missions, suggesting that oil and gas emissions are, indeed, much larger than published estimates.
“What our study has done is not only provide a first estimate of large methane releases that can only be seen from space, but also show how these detections relate to the whole story. This is a giant step towards overcoming the current limitations of the methane surveillance system and getting the long elusive big picture,” Clément Giron said.
The team will continue to look at methane emissions from oil and gas activities but also coal extraction and farming activities thanks to high-resolution data from recent satellite missions. These new instruments provide much higher resolution images but cover parts of the globe less frequently. For global and daily coverage will Sentinel-5P remain an important tool for future emissions monitoring.
“National greenhouse gas emissions rely primarily on self-reporting, while atmospheric data offers a more rigorous approach to emissions accounting, more independent and more transparent,” Lauvaux added. “In the future, atmospheric measurements will play a more important role in mitigation policies by identifying actionable measures and by monitoring the implementation of climate actions.”
The study is published in Science here.