Leading oil economists who voted Yes in Scotland's independence referendum have warned first minister Nicola Sturgeon that the spectacular collapse of global oil prices has dealt a "big blow" to the economic case for leaving the UK.
Ahead of 2014's referendum, the Scottish government based its case for independence on the price of a barrel of oil remaining at around $113. Since then, the price has plummeted: At one point on Thursday it fell below $30 a barrel for the first time in 12 years, before recovering slightly to just about $30. That leaves a possible £30 billion gap between the revenues predicted by the SNP and what may actually be recovered.
Now the prominent Yes-voting economists cited by the SNP in its campaign material have told BuzzFeed News the party will have to develop a new economic argument for independence that does not rely heavily on oil.
"What's happened has certainly made it more difficult [to make an economic case for independence]," said Professor Sir Donald McKay, a leading expert in North Sea energy and the former chair of Scottish Enterprise, who made headlines in August 2014 when he endorsed the SNP's plans for independence. "A lot will depend on what they do from here on in, and if they manage to change to a more flexible argument than before."
He added: "To make the case for independence now you've got to demonstrate, in the long run, you can develop the economy sensibly. Oil is no longer the driving motive, even though for quite a few years yet there could still be a low but stable level of employment in that sector."
Professor John Howell, the chair of petroleum geology at the University of Aberdeen, was cited in Scottish government press releases after he backed the SNP's plans for independence and said there remained a substantial volume of oil left to recover from the North Sea.
Howell is still strongly in favour of independence, but said the economic case had been dealt an undeniable blow by the collapse in oil prices. "I'm an SNP supporter and I believe in independence, but the economic case, if we were to have another referendum next year, I think it would be very heavily dented," he said.
"The last argument for independence was quite simple: 'We have a lot of oil, we are rich, we can be like Norway.' The next argument will have to be more complex, but I don't think it's damaged beyond repair."
Aberdeen, the capital of the UK's oil and gas industry, has faced the brunt of the fall in prices over the past year. As many as 60,000 jobs have been lost, either within the industry or in the services that relied on the wealth it brought into the city, and the property market has been damaged to the extent that many of Howell's students are renting heavily discounted luxury flats that were built for wealthy oil executives.
While there remains "a great deal" of oil to be recovered from the North Sea, Howell said, it could be "game over" for Scotland's oil industry unless the large, existing oilfields start making money again within the next year, as otherwise they risk being decommissioned by oil companies and taken out of action permanently.
But he added: "If you imagine the industry goes into a steep decline in the next year, there is still an amazing resource of people with engineering skills in Aberdeen, many of whom have have been paid off from their jobs in the oil industry. That resource can be harnessed to build alternatives, whether that's in energy or other science and engineering industries."
Alex Russell, a professor of petroleum accounting at the Aberdeen Business School, also gave the Yes campaign a boost when he backed independence the week before the referendum in September 2014.
He remains hopeful that Scotland's oil industry will recover by 2025, but also fears that the large oilfields may be closed down, which would prevent such a recovery. "The low oil price is a blip, I would say; at some point oil prices will rise," said Russell.
"There's absolutely no doubt there's the same quantity again of oil that they've already taken out of the North Sea still there and it will be economically viable at some point. But if we move into decommissioning mode, which is on the cards, that won't happen. Right now the oil companies and the government are shooting themselves in the foot."
However, he added that he still supports independence for Scotland. "I very much believe if we were an independent Scotland, with a low population, with the reserves of oil that are out there, the case could still be made for Scotland going for independence and becoming the most prosperous part of Britain."
If people in Scotland had voted Yes to independence, the Scottish government's timetable would have seen the country become independent on March 24 this year. Professor McKay said, under current economic circumstances, adapting to independence would have proved "very difficult", but not impossible.
"It wouldn't have been easy," he said. "Scotland would have expected to control the majority of the oil reserves, but in present circumstances that would not be a huge bonus. The Scottish government would have had the responsibility to get costs under control, stabilise job losses, and they would not have had any significant tax revenues from it until the price recovers.
"It would have been difficult, and certainly not what they would have desired. But would it have been impossible? Probably not."
Jamie Ross is a Scotland reporter for BuzzFeed News and is based in Edinburgh.
Contact Jamie Ross at firstname.lastname@example.org.
Got a confidential tip? Submit it here.