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Rosebank oil field: the 250 million tonne climate question facing the UK

The debate over the UK’s energy future has just intensified. At the centre of it all is the Rosebank oil field, the largest undeveloped oil and gas discovery in UK waters. And now, for the first time, we have a clearer picture of its full climate impact.

If the project goes ahead, developers estimate that burning the oil extracted from Rosebank could generate nearly 250 million tonnes of carbon dioxide over the next 25 years.

To put that into perspective: the UK’s total emissions in 2024 were about 371 million tonnes. In other words, Rosebank alone could represent a climate footprint approaching two-thirds of the country’s current annual emissions, spread over a quarter of a century.

That’s a number that’s hard to ignore.

For more information about the work environmental lawyers do day to day, read this Practice Area Profile to hear from Osborne Clarke LLP associate Arthur Hopkinson.

What’s Rosebank?

Rosebank lies around 80 miles North West of Shetland, in deep waters of the North Atlantic. It’s estimated to contain up to 300 million barrels of oil, along with some gas, making it one of the most significant untapped fossil fuel reserves in the UK sector.

The field is owned by Norwegian energy giant Equinor and UK-based Ithaca Energy.

Originally approved in 2023, the project seemed set to move forward. However, in January, a court ruled that the environmental assessment carried out by the developers had failed to fully account for the emissions that’d result from burning the extracted oil and gas, not just producing it.

That ruling changed everything.

The legal turning point

Until recently, UK fossil fuel projects were mainly required to assess the environmental impact of extraction, drilling, transport and processing.

However, in June last year, the Supreme Court of the UK made a landmark decision: authorities must also consider the emissions produced when the fuel is ultimately used.

The case stemmed from a local gas development challenge in Surrey, but its implications were nationwide. Environmental groups including Greenpeace UK and Uplift successfully applied the same reasoning to Rosebank.

The result? Equinor had to go back and calculate the full lifecycle emissions of the project.

And the new numbers are staggering.

From 4.5 million to 249 million tonnes

Originally, Rosebank’s emissions were estimated at around 4.5 million tonnes of carbon dioxide, covering operational impacts only.

The revised figure? 249 million tonnes over 25 years.

That’s more than 50 times higher than the initial estimate.

The reason for the dramatic increase is simple: the new calculation includes emissions from burning the oil and gas once they reach consumers, whether in the UK or abroad.

This distinction matters. Fossil fuels don’t just emit carbon when they’re extracted. The vast majority of their climate impact comes when they’re burned for energy.

Developers say it’s “not significant”

Despite the eye-catching total, Equinor has stated that the emissions are “not significant” when viewed in the context of global climate commitments.

Their argument rests on a broader perspective: global oil demand continues, and if Rosebank doesn’t supply that oil, another producer somewhere else will. In that sense, they imply the project doesn’t necessarily increase total global emissions, it shifts supply.

However, the company has acknowledged that if global warming exceeds 2°C, Rosebank could have a “significant” cumulative climate impact due to its sensitivity within the wider system.

That nuance hasn’t softened criticism.

Critics call it a climate contradiction

Campaigners see the newly published figures as confirmation of their concerns.

For environmental groups, Rosebank represents a fundamental contradiction: how can the UK claim climate leadership while approving one of its largest new oil fields?

The UK has legally committed to reaching net-zero emissions by 2050. At the same time, senior ministers, including energy secretary Ed Miliband, have repeatedly emphasised the need to reduce reliance on fossil fuels.

Miliband recently described the UK’s dependence on oil and gas as its “Achilles’ heel”, arguing that clean power is the only sustainable way to lower energy bills and protect the economy from volatile global markets.

Against that backdrop, approving a project that adds hundreds of millions of tonnes of future emissions raises obvious questions.

Will Rosebank lower energy bills?

One argument often made in favour of new domestic oil and gas projects is energy security.

Supporters suggest that producing oil at home reduces reliance on imports and strengthens the UK’s position in global markets.

But there’s a catch: Rosebank’s oil isn’t reserved for the UK. It’d be sold on the international market at global prices. There’s no guarantee that it’d directly supply British households or significantly reduce bills.

In fact, the UK’s independent climate advisors said in 2022 that additional domestic extraction would likely have only a marginal effect on prices.

So, while Rosebank might support jobs and tax revenues, its direct impact on consumer energy costs could be limited.

The bigger picture: supply vs demand

At the heart of the debate is a deeper question: does limiting new fossil fuel supply meaningfully reduce emissions if global demand remains high?

Producers argue that as long as the world uses oil, someone will extract it. Environmental groups counter that expanding supply locks in infrastructure and delays the transition to renewables.

Both perspectives highlight a difficult truth: the energy transition isn’t just about switching technologies, it’s about reshaping economic systems built over decades.