The UK has been warned it has badly underestimated the level of methane emission from its oil and gas sector.

Using what they say is a more accurate method for calculating methane emissions from offshore oil and gas production, teams from Princeton University and Colorado State University  calculated that the United Kingdom “severely underestimates” its greenhouse gas emissions.

Researchers added the new measurement suggest that as much as five times more methane is being leaked from oil and gas production than reported.

Methane is the second most important greenhouse gas after carbon dioxide, contributing about 1 degree Fahrenheit of present-day global warming relative to pre-industrial times. One major source of methane to the atmosphere is the extraction and transport of oil and gas. Countries are obligated to report their greenhouse gas emissions to international bodies such as the United Nations Framework Convention on Climate Change, but recent studies suggest that the current methods for calculating methane emissions rely on outdated and incomplete information and may not accurately represent actual emissions.

The researchers explained that the current method for estimating methane emissions from offshore oil and gas production in the United Kingdom “systematically and severely underestimates emissions”. The study concluded that as much as five times more methane is being emitted from oil and gas production in the UK than what the government has reported.

Since many other countries use similar methodologies to calculate methane emissions from oil and gas production, this severe underestimation is likely not confined to the UK alone, the team warned.

“It is critical to know when, where and how much methane is emitted from each of its sources in order to prioritise emission reductions,” said Denise Mauzerall, a co-author and core faculty member of the Centre for Policy Research on Energy and the Environment at Princeton University. “We hope our work will facilitate improved emission estimates and reductions not only from the UK but also from other countries producing methane from oil and gas extraction.”

“Due to its climate and indirect health impacts, methane is a precursor for ozone which is an air pollutant that damages human health and crops, methane mitigation has recently become a global policy priority,” added the study. “Its relatively short lifetime of about 12 years and high heat trapping ability per molecule makes reducing methane emissions among the most effective ways to slow the rate of climate warming. As a result, in 2021 countries signed the Global Methane Pledge, committing to reduce methane emissions by at least 30% of 2020 levels by 2030. To track progress, countries compile national emissions data into inventories, such as the UK’s National Atmospheric Emissions Inventory (NAEI), which are then reported to international monitoring bodies.”

This study focuses on methane leakage associated with discovery, extraction, and production of oil and natural gas. These methane emissions are typically calculated by multiplying the activity level of various processes – namely venting, flaring, processing and combustion activities on production platforms, offshore oil loading, and gas transfer by high-pressure pipelines – by “emission factors,” which are standard estimates of the methane emissions associated with each activity.

The researchers found that the emissions factors used in the UK’s reporting are either outdated, rely on unpublished or publicly unavailable industry research, or use generic values recommended by the IPCC. Furthermore, these emission factors are usually “static,” meaning that they are not sensitive to factors such as environmental conditions and management practices which could affect emissions from various processes. In addition, leakage can occur when the off-shore rigs are idle – an “activity” that does not currently have an associated emission factor.

“Methane emissions from offshore facilities are currently largely uncertain, and because sources on facilities only emit for a short time period, using direct survey methods such as satellite or drones will probably only capture about 25% of the actual emissions,” said Stuart Riddick, lead author and research scientist at Colorado State University. “To generate representative baseline emissions across the sector, we need to work with industry to develop practical, effective, and collaborative measurement strategies.”

“We are hopeful that our work will facilitate more accurate emission inventory development and lead to critically important reductions of methane leakage – a win for both industry and the environment,” Mauzerall said.