The Abigail oil field will be developed by an Israeli company called Ithaca Energy.

Although the reserves are relatively small, Abigail's approval has sparked a backlash from campaigners who say that new oil and gas fields are incompatible with the UK's net-zero ambitions and its global position as a climate leader.

But the operations director of the Oil and Gas Authority (OGA) told Sky News that oil and gas will continue to be part of the energy mix for decades to come, even as the North Sea basin continues its decline and the transition to renewable energy gathers pace.

Asked about the general principle of approving new fields, Scott Robinson said: "I understand the argument, it's a difficult and very complex situation to come to the right answer on, but if we stop new developments, the UK will just become more dependent on imports, and we'll reduce our own security of supply options."

This contrasts with the position of COP26 president Alok Sharma, who recently told Sky News that he rejected the principle that more North Sea gas would better protect the UK from supply difficulties.

Mr Sharma said that we need to be doing of "more of what we have been doing - which is building forward on renewables and obviously investing in nuclear".

"I think that is the answer ultimately to all of this," he added.

'Absolutely no room for growing oil and gas supply'

The differing arguments illustrate the tension around the future of the North Sea, most recently symbolised by the controversial Cambo oilfield that was halted in the face of significant public pressure.

Greenpeace oil and gas analyst Charlie Kronick told Sky News: "The reality is we have to (virtually) stop using oil and gas by 2050, and we have to reduce the amount of oil and gas we use within a decade by nearly 50%.

"There is absolutely no room for growing the supply of oil and gas in the UK or anywhere.

"The International Energy Agency, the world's leading energy think tank, declared twice last year that there's enough oil and gas in the world in production right now, to take us beyond the limits of the Glasgow climate agreement and the Paris Climate Agreement.

"We just don't need to look for any more."

Apart from the ongoing debate about the pace of the transition away from fossil fuels, the companies that remain in the North Sea have promised to clean up the carbon intensive drilling and extraction process.

At the moment, the industry's operational emissions make up 3-4% of the UK's total.

The independent Climate Change Committee believes that the sector should be able to reduce those emissions by 68% by 2030, in line with economy-wide commitments.

But the industry has only committed to reducing emissions by 50% by that date, and getting to net-zero by 2050 by using renewable and other clean energy sources to power rigs and drilling.

Major emissions target could be missed

Although carbon emissions are falling, the OGA's own projections suggest the 2030 target may be missed.

Mr Robertson said: "It's big bits of kit, it's big investment, there's not just technological and regulatory (challenges), there are a lot of barriers to overcome.

"But we're peeling away at the skin of the onion and working away at them.

"There's commitment to do it from regulators and industry."

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Data from research and intelligence company Rystad Energy, which has been shown to Sky News by Greenpeace Unearthed, suggests that even though absolute emissions are falling, the intensity of carbon emissions actually increased last year.

Emissions intensity is measured by the amount of carbon produced per barrel of oil or equivalent. It provides a way of assessing how clean or dirty a particular process is.

Rystad's projections for UK North Sea oil and gas operations show that emissions intensity had been declining since 2018, but increased by 15% in 2021 compared to the year before.

The main driver of this was planned repair work to a major pipeline. But other factors include the North Sea being a declining basin, and it's becoming harder and more carbon intensive to remove oil and gas as reserves dwindle.

Another is that the UK has not yet halted routine flaring as part of the oil and gas production process.

Norway's North Sea oil and gas industry, by comparison, has around a third of the emissions intensity, despite operating in the same ocean in relatively similar conditions.

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