Methane
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Methane is the second-most powerful greenhouse gas after CO₂, and it's being leaked, vented and flared from onshore oil and gas sites across the UK. Here's what you need to know.
What is methane and why does it matter?
Methane (CH₄) is a small and simple molecule, consisting of just one carbon atom surrounded by four hydrogen atoms. Its size and structure make it incredibly light and agile, enabling it to escape easily into the atmosphere through even the smallest leaks or gaps.
This tiny molecule, invisible to the eye, traps heat at a rate approximately 80 times more powerful than carbon dioxide over 20 years. In other words, methane has an immense warming effect over a short period of time. This means that cutting methane is one of the fastest, most impactful ways we can cool the planet.
Onshore oil and gas operations in England are a significant but poorly monitored source of methane emissions. Methane pollution occurs across the entire lifecycle of this sector, from exploration and production, to site closure and abandonment.
Methane is routinely released into the atmosphere in three distinct ways: it leaks unintentionally from ageing pipework, valves, and wellheads (what the industry calls fugitive emissions); it is deliberately vented as a direct release during operations and maintenance; and it is flared, burned off as waste gas through a flame at the site. Flaring converts some methane to CO₂, but it is an imprecise and often poorly monitored process. Venting releases the gas directly and unburned. And leaks, by their nature, go largely undetected unless actively surveyed with specialist equipment.
Regulation carried out by the Environment Agency is currently heavily reliant on industry self-reporting: essentially asking companies to mark their own homework. Venting and flaring of gas are still common, leak detections infrequent with no deadline for repairs.
Methane pollution from onshore oil and gas is currently not included in the 2025 UK Government's Methane Action Plan, undermining the credibility of the UK's wider methane reduction commitments, particularly as it continues to present itself as a climate leader.
The science is unambiguous. Methane's short atmospheric lifespan means every tonne we prevent from entering the atmosphere has an immediate and measurable impact on global temperature.
Methane sources in the UK
While farming and waste sectors have higher emissions, methane reduction from fossil fuels is considered the easiest and most cost effective. Leaks from machinery can be fixed using existing technology, often at no net cost. In contrast, agricultural methane is diffuse, produced by billions of livestock, and waste methane is generated by countless diverse landfills, making abatement challenging.
Although methane emissions have declined significantly following the near-complete phase-out of coal production in the UK, substantial opportunities remain to achieve further reductions. Depleting reservoirs at oil & gas production sites are prone to higher emissions and there is permitted and routine venting, flaring and widespread leaking of methane across the sector.
Livestock digestion (enteric fermentation) and manure management are major sources. Agriculture accounts for roughly 40% of UK methane emissions.
Decomposing organic matter in landfill sites produces methane. Efforts are underway to divert food waste from landfills and gas capture has improved, yet legacy sites and inadequate monitoring mean significant emissions continue undetected.
It's not just the climate at risk
Methane is a precursor to tropospheric, or ground-level, ozone, a toxic, irritant gas which has significant negative effects on the health of humans, animals and plants. In our warming world, climate change creates more ozone from natural and human-made sources as temperatures get hotter.
"Good up high and bad nearby"
Ozone exists in the upper atmosphere (stratosphere), which is good, as it protects life from solar radiation. However, ozone in the air we breathe at ground level is bad, as it acts as a toxic air pollutant.
Ground-level (tropospheric) ozone is harmful to anything that lives, whether it be a bean, squirrel or human. It is linked to 1 million premature deaths annually worldwide (WHO).
Adverse Health Impacts: exposure to air pollutants associated with oil and gas operations can contribute to the following:
Benzene is a Group 1 carcinogen. It is routinely detected at onshore oil and gas sites in the UK alongside methane leaks. There is no safe level of exposure.
Ozone is a potent phytotoxin that significantly damages plant tissue, inhibits photosynthesis, and reduces crop yields. In 2022, ozone pollution caused an estimated £1.7 billion in losses for potato and wheat crops across Europe.
European Environment Agency (EEA) · 2022
Exposure to fossil fuel pollutants can impact plant growth in the following ways:
Ozone shortens the time that leaves stay on trees, which means less food for the trees. That reduces stem and root growth, which makes them more susceptible to drought and insects.
Uncontrolled methane emissions don't just warm the climate; they threaten the agricultural systems that feed us. Reduced crop yields from ozone damage compound the food security risks already posed by climate change.
Tropospheric ozone is a distinctive problem to solve. Because it isn't emitted directly but forms from a mix of precursor gases and pollutants, tackling it demands rapid, coordinated action across several greenhouse gases and air pollutants at once, and across the many industries that produce them.
We need to tackle multiple pollutants together, including methane and other short-lived climate pollutants, rather than one by one, to avoid unintended consequences, maximise co-benefits and ensure ozone reduction efforts are effective given its complex chemistry.