Global assessment of oil and gas methane ultra-emitters

The paper notes that large discrepancies between various methane accounts remain unexplained, complicating the link between the rise of methane in the atmosphere to anthropogenic or biogenic sources, a decline in sinks, or changes in anthropogenic/biogenic sources. The paper also notes that a recent dataset from the European Space Agency Sentinel 5-P satellite mission has been made available, exposing cases of unintended leaks of methane. The paper examines this dataset to statistically characterise visible ultra-emitters of methane from oil and gas activities.  

For the study, the authors apply an automated plume detection algorithm and quantified emissions using the Lagrangian particle model HYYSPLIT. This helps identify ultra-emitters, defined as emitting >25 tons/hour. The study finds that the number of detections of such emitters globally totals >1800 single observed anomalies from 2019 to 2020, many of which are in Russia, Turkmenistan, the US, the Middle East, and Algeria and most of which are from oil and gas production and transmission activities.  

When emissions are adjusted for uncertainties, oil and gas ultra-emitter estimates are 8-12% of global oil and gas methane emissions; a contribution excluded from many current inventories. Furthermore, Turkmenistan’s contributions to methane emissions from oil and gas production are likely to be double current estimates. 

The study also estimates abatement costs to eliminate ultra-emitter methane emissions using analyses from the International Energy Agency (IEA), the US’s Environmental Protection Agency (EPA), and the International Institute for Applied Systems Analysis (IIASA). Due to the cost-effectiveness of tackling ultra-emitters relative to other O&G sector mitigation measures, most countries realise net savings, such as Russia, Kazakhstan and Turkmenistan, at between ~$100 to $150 per ton, the US at ~$250 per ton, and Algeria at $400 per ton. Only Iran sees a net cost of ~$60 per ton. 

The study also looks at societal costs, assigning $4400 per ton of methane, based on a valuation from the Global Methane Assessment. This accounts for the impacts of methane on climate and surface ozone, both of which affect human health (mortality and morbidity), labour productivity, crop yields, and other climate-related impacts. The net benefits of controlling high emitters in the six aforementioned countries are: ~$6 billion for Turkmenistan, ~$4 billion for Russia, ~$1.6 billion for the US, ~$1.2 billion for Iran, and ~$400 million for Kazakhstan and Algeria (each). 

With respect to benefits to the climate, the study finds that eliminating methane emissions from ultra-emitters would result in “0.005° ± 0.002°C of avoided warming over the next one to three decades on the basis of linearized estimates from prior modeling”, preventing “~1600±800 premature deaths annually due to heat exposure and ~1.3±0.9 billion hours of labor productivity lost annually due to exposure to heat and humidity, with the latter valued at ~$200 million per year”. 

The article can be used to support measures to address methane emissions from oil and gas production, impose strict conditions on oil and gas permits to manage methane emissions, and provide a technical basis to more accurately measure the methane emissions from oil and gas activities around the world. It also highlights that natural gas supplies from specific regions may have very high associated methane emissions, challenging arguments that natural gas is lower carbon than other fossil fuels such as coal and oil.