HERE'S a fascinating fact.

The Government Pension Fund of Norway (Global) – otherwise known as the Oil Fund – is forbidden to invest in a major Scottish employer. It's nothing personal, just a matter of what the Norwegians recognise as ethics.

How dare they? Simply because they can. Norway's oil fund was worth $683.7 billion at the end of last year. Its value is expected to reach $1 trillion by 2019. It is the biggest pension fund on the planet and owns, among other things, 1.78% of all the stocks and shares in Europe.

With power – in some countries at least – comes responsibility. Scandinavians tend to be quaint in such matters. The Norwegian oil fund is guided, in fact ruled, by an ethical council and provided with a list of enterprises which are not to be granted a single investment krone.

Imperial Tobacco? Not a chance. Rio Tinto? Not if they continue to mess up the environment. Lockheed Martin? The Norwegians are funny about cluster bombs. So why not Serco, a fine British company that has prospered since our governments took to handing out contracts for privately-run prisons, the Docklands Light Railway, Northlink Ferries and much else besides?

Ah, but the Norwegians object to the multi-national's part in the consortium running the Atomic Weapons Establishment and the fleet support services provided by its Serco Denholm joint venture. HMNB Clyde – Faslane, Coulport, Trident submarines – is not something Norway will support.

For those who incline to nationalism, this is all so richly ironic you could choke. Here are some of us hoping for independence, in part to get rid of Trident, in part to secure some of Scotland's oil wealth. Here, meanwhile, are the Norwegians wielding their oil money to put beyond the ethical pale those who make Trident possible.

This part of the argument over Scotland's North Sea wealth is not often mentioned. We are so bogged down with forecasts of future oil prices and the ability to pay for pensions if London's "largesse" is withdrawn – the largesse now being cut hand over fist in the name of austerity – we fail to consider what an oil fund could mean. You can help yourself and, if you've a mind, spread some decency in the world.

Norway, goes the cliché, puts its money away for a rainy day. That's not strictly true: the Norwegians operate a self-imposed fiscal rule that prevents the use of more than 4% of total oil fund wealth for normal spending. Just like us, it runs a non-oil structural deficit – it needs the North Sea – but oil revenues and fund earnings have shown a handy tendency to grow by more than 4%. So the fund, too, continues to grow.

Things are expensive in Norway. People complain about poor roads and unsatisfactory schools. There is a continuing argument over the need to tolerate these and any other problems when $683.7bn is sitting, as it were, in the bank. But Norwegians have free healthcare, free university tuition, the right to a full year's sick pay – and the usual doleful economists who say they are too dependent on their "lavish" welfare state. It's a tough life.

The Norwegian oil fund was only established in its present form in 1990 – a decade after Britain's Conservative governments first decided they would rather spend North Sea revenues on unemployment than saving. No party since has made a serious proposal for a UK oil fund. Yet a Scandinavian country of just 4.9 million people, with few other natural advantages is well prepared to face the future.

The Norwegians are not naïve. They expect oil revenues to diminish in the years to come. The first question is: by how much? And secondly: when? Scotland's unionist politicians tell us you cannot plan your economic future around a volatile commodity price. So what happens if you have no other choice?

Two years ago, Norway's finance ministry came up with a set of forecasts. One said that if everything goes wrong in the years ahead, the oil fund might be worth "only" $455bn by 2030. A second, favoured by the ministry, settled on $1.3 trillion. The jackpot figure, if everything goes right and the fund is not plundered, was $3.3 trillion.

All of this is being done for two reasons. First, to supplement, not replace, government income; secondly, to secure the country against the day when revenue from oil taxes, licence payments and dividends from the part-nationalised – now there's an idea – Statoil enterprise have disappeared. None of that seems like an irrational project.

All our arguments begin from the unionist assumption that an independent Scotland would have to grab and spend every penny of revenue as it comes, just to stay solvent. On this view we would not have the cash – ever – to spare for an oil fund. This leaves a question hanging: Why were those 4.9 million Norwegians prosperous enough before the arrival of North Sea oil to put aside temptation? Why them and not us?

But let's say it's true. Let's say the oil industry is planning to invest £13bn in the North Sea this year – for it is – because it expects reserves to last for 40 years. Let's say the best we could get out of that would be the chance finally to stabilise the Scottish economy, give it a firmer footing, and begin to build the non-oil sector. It wouldn't make millionaires of us all, or put $683.7bn in the national bank, but I'd call it a start.

Unionists argue that a diminishing resource will also diminish in value, but struggle to say why. Because of American shale deposits? Because the North Atlantic is tricky? Those are factors, but far from the whole story – "volatile" is not a synonym for "worthless". Part of the point of an oil fund is to balance fat years against lean.

Some oil-rich countries can be silly, pricing petrol in pennies or squandering billions on the nuclear weapons that upset Norway. Some, such as Venezuela, have decided an assault on poverty is a decent use for the wealth generated by a filthy commodity. Only the fatuous would tell you to pretend the oil isn't really there when it sits on your doorstep and could change your society.

When they're not worrying about unethical investments, the Norwegians fret over investing 60% of their oil fund on the stock markets. That's a truly volatile business, capable of polluting the world in an instant. Meanwhile, we have an SNP government obsessed with renewable energy, as though clean power might make amends – all ironies included – for demanding our share of the North Sea's precious filth.

Renewables are the future, of course, because in the future there will be no other choice. That doesn't mean we should put aside the chance of prosperity today. Forty years ago, the Norwegians took the opportunity refused to Scotland. Their small country remains an example of what was lost.