Everything you need to know about Jackdaw, Rosebank, and the debate over UK oil and gas

If approved, Rosebank is expected to fill up to 500 million barrels of oil over its 25-year lifetime.

But that increased supply does not necessarily guarantee cheaper energy bills for people in the UK. Prices are determined by international markets which are vulnerable to shocks such as the conflicts in Ukraine and Iran.

Most of the oil produced from Rosebank would be sent to the Netherlands because the UK's remaining refineries are not equipped to process the heavier type of crude oil extracted from the North Sea.

If any of the refined products - such as diesel or jet fuel - were to be used in the UK, they would then to be reimported.

When plans for Jackdaw were unveiled in 2022, developers said it would produce enough gas to power 1.4 million homes.

It would be a relatively simple process to connect Jackdaw to the UK energy system, meaning gas could be quickly pumped to the mainland.

Announcing that the project would go ahead, the UK government said it was expected to increase domestic gas production by around 6% at its peak.

It said that over its 11-year lifespan, Jackdaw would protect hundreds of jobs and add an estimated £2.9bn to the UK economy.

Backers say opening the fields would improve the UK's energy security.

Yet Fatih Birol, a leading energy economist at the International Energy Agency, told The Guardian, external earlier this year that new drilling in the North Sea "would not change much for the UK's energy security" or bring down energy bills.

He said that the UK would still be reliant on oil and gas imports, with prices set internationally.

Both Jackdaw and Rosebank are operated by Adura, a joint venture between Norwegian company Equinor and Shell. Aberdeen-based firm Ithaca also owns 20% of Rosebank.

It has estimated that Jackdaw could produce 35.8 million tonnes of carbon over its lifetime, the equivalent of 90% of Scotland's emissions for 2023. Adura said a more likely estimate was about 23.6 million tonnes - equivalent to 60% of the 2023 figure.

Those figures are dwarfed by the projections for Rosebank - almost 250 million tonnes of planet-warming emissions.

Yet Adura's updated environmental impact assessment, ordered by the Court of Session, says that emissions from Jackdaw would "not materially influence" global warming.

The firm says that displacing imported liquified nature gas from the United States with gas from the Jackdaw field would save the equivalent of four million tonnes of CO2.

Campaign groups say that would not lower worldwide emissions as the US gas would still be sold and burned elsewhere.

Adura also said the climate effects would be "minor" because the UK has a "well-regulated industry" aligned with the Paris Agreement, a legally binding commitment to limit global warming to between 1.5 and 2C.

However, Greenpeace UK chief scientist Doug Parr said opening a new field was "wholly incompatible" with the Paris Agreement.

Industry body Offshore Energies UK (OEUK) has said Rosebank and Jackdaw would support a peak of more than 3,500 jobs during the construction phase.

It says the fields would support 880 jobs, external throughout during their lifespans, with an average salary of £85,850.

OEUK also says they would provide £1.4bn in tax revenues by 2029, rising to £3.8bn by 2034.

Such figures are particularly attractive in the north-east of Scotland, which is contending with the decline of an industry which has long been its economic lifeblood.

According to research for the UK Parliament, external, about four fifths of the oil and gas from British-controlled parts of the North Sea had been extracted by 2024.

Campaign group Uplift says that trying to prop up the declining industry with the Rosebank and Jackdaw fields would only delay the transition to greener energy production, which it argues, external is needed to protect the environment and support jobs.

"The only way to protect workers, supply chain firms, and communities that are currently dependent on the oil and gas industry from this decline is to invest in renewables and other industries that have a long-term future," it says.

Opening Rosebank and Jackdaw would deliver big profits for energy firms, and little benefit to taxpayers, Uplift adds.

Ami McCarthy, head of politics at Greenpeace UK, said: "Trying to squeeze the last few drops of expensive oil and gas out of the North Sea while the world is reeling from climate impacts is beyond ridiculous."