Scientists have called for investigations into the levels of methane released from oil and gas sites after a study concluded that global levels of some hydrocarbons in the atmosphere had been underestimated.

The conclusion could challenge the climate change case made by supporters of UK fracking, who argue that methane in natural gas has a lower carbon footprint than coal.

The study, published yesterday in Nature Geoscience, found that emissions of ethane and propane released during fossil fuel extraction and distribution could be two-three times higher than previously thought.

The authors from York, Oslo and Colorado are now calling for further research into emissions of methane, one of the most damaging greenhouse gases, that could also be released from hydrocarbon sites.

One of the authors, Professor Lucy Carpenter, from York University, said:

“We know that a major source of ethane and propane in the atmosphere is from “fugitive” or unintentional escaping emissions during fossil fuel extraction and distribution. “If ethane and propane are being released at greater rates than we thought, then we also need to carefully re-evaluate how much of the recent growth of methane in the atmosphere may also have come from oil and natural gas development. “The current policy case for fracking, for example, is partly based on the belief that it is less polluting that coal.”

The researchers used data on ethane and propane levels from 20 observatories across the world and compared it with simulations using emission inventories.

They concluded that observations of ethane and propane could be reproduced in simulations only where fossil fuel emissions were assumed to be two to three times higher than the level in the inventories.

Another author, Professor Ally Lewis, said:

“Levels of ethane and propane declined in many places the 1980s and 1990s, but global growth in demand for natural gas means these trends may be reversing.”

Propane and ethane are the most abundant non-methane hydrocarbons in the atmosphere. They are particularly harmful in large cities where they react with car emissions to form ozone. This is a greenhouse gas and a component of smog.

Professor Lewis said:

“The effects of higher ozone would be felt in the rural environment where it damages crops and plants, and in cities on human health. “Tropospheric ozone causes a variety of serious health complaints and along with particulate matter and nitrogen dioxide is one of the three major causes of pollution-related deaths.”

Industry response

The industry body, UK Onshore Oil and Gas, has challenged the findings. Its Chief Executive, Ken Cronin, said:

“The research was unable to distinguish between the emissions associated with different fossil fuels, including coal. To apportion such emissions solely to oil and gas, and specifically shale gas, would be a misrepresentation of the dataset. This contrasts with a lack of large ethane or propane plumes identified in the North Sea, a large oil and gas producing offshore field. “This global analysis of ethane and propane emissions reveals that several countries, many of which the UK imports oil and gas from, have higher emissions than had been previously reported- exemplified by large ethane and propane emissions in Middle East, Russia and Africa. “Relying on data collection from 2011 is outdated as far as shale gas is concerned. Research and Development improvements since then, such as the use of ‘green completions’ and leak detection and repair policies in the US have ensured reduced emissions from shale gas operations. “This research is an example, once again, of how some datasets are not applicable and unappreciative of the UK regulatory framework for shale gas production. The UK is applying the best available techniques for emissions reduction of onshore shale gas operations from exploration to decommissioning, as well as emissions monitoring from before a well is drilled or hydraulically fractured.”

Campaign response

The Green Party MEP for south east England, Keith Taylor, said:

“The scientific evidence exposes, time and time again, the destructive ignorance of a Conservative government that continues to pump £6bn a year of support into a fossil fuel industry that has set Britain on a course to miss its legally-binding domestic carbon targets and international Paris agreement obligations.” “Theresa May’s repeated and steadfast insistence on fast-tracking fracking, in particular, flies not only in the face of the evidence, highlighting the climate destruction it wreaks, but also the local democracies and communities over which the industry and Government is riding roughshod.” “This new report is just the latest in a long line to expose the urgent need to ban fracking. It reinforces the NASA report, from just two months ago, that identified the fossil fuel industry, particularly fracking, as the single largest driver of rising in methane levels in our atmosphere. It’s worth noting that methane has more than 80 times the climate change impact of carbon dioxide emissions.” “The findings put Theresa May’s support for fracking – which the Government wants to see fast-tracked across England – completely at odds with her green promises. Theresa May might claim the Tories are environmental world-leaders but, with Scotland’s fracking ban already in place, they’re not even leading in the UK.” “The Government can no longer ignore the overwhelming scientific evidence nor its own polls. The British public is clear and consistent: they don’t want to be locked into climate destructive fossil fuels, they want a clean, renewable energy future. It’s finally time for the Tories to listen. Fracking has never been and never will be a bridge to a clean energy future that it is already in our power to build.”

Discrepancy between simulated and observed ethane and propane levels explained by underestimated fossil emissions, published on 26 February 2018 in Nature Geoscience