Like the curtain being drawn back on the Vatican balcony last week, Alex Salmond will emerge today in the Scottish parliament and tell the Scottish people "We have a date". Unlike last week, there are unlikely to be any big surprises if, as we expect, the date falls close to the one he leaked to the Scottish Sun last year.

In many respects, today's announcement changes little. The campaigns on both sides – Better Together and Yes Scotland – have long been established, the day-to-day arguments between the two sides are being played out in the Scottish press and people across Scotland already knew the referendum would be coming next year.

The decision about Scotland's future will, rightly, begin and end in Scotland, but the impact is one that will be felt across the whole of the United Kingdom. Today, I hope, is the day that the countdown starts and the rest of the UK starts paying more attention to the decision that we are about to take.

Why does this matter beyond Scotland's borders? Firstly, regardless of your political outlook, supporters of keeping the UK together will share an emotional attachment to the country where they were born. Scotland is part of the UK, and people across the country feel this. David Mitchell's appeal to British patriotism summed this up when he concluded that Scottish separation would mean anyone who identifies themselves as British will have "lost their country". You need to look no further than Scotland's reaction to the Olympics to see that this would be true. And the SNP knows this.

That's why we've had the sight of senior SNP figures, notably in the form of Nicola Sturgeon last December, try to drop nationalism as an idea, tell us we'll all still be British and, instead, adopt social democracy as their primary purpose by trying to portray the SNP as the true inheritors of the postwar consensus.

For those of us who have spent a lifetime fighting for social justice from the left, we know that nationalism never has been, and never will be, the solution. As the SNP fights the referendum with a Tory-led UK government in power, this might be a good tactic, but it's not truthful politics from a party that has Scottish separation, whatever the cost, at the top of its list of objectives.

The SNP wants to say it believes in Britain, while also saying that the partnership or any of its institutions can never work in Scotland's interests. We know that isn't the case. From the welfare state to the NHS to the British trade union movement, the UK – underpinned by social democratic institutions and ideas delivered by Labour – has worked in Scotland. And, since 1999 devolution has meant that we can benefit from a strong Scottish parliament, without losing the benefits of partnership.

Scottish Labour's voice in the debate speaks to some deep rooted principles that are understood across the UK. We are in a family of nations that pools risks and redistributes reward based on need. To say that Scotland receives more than the average UK public spending, as the Scottish government's own figures highlighted last week, is not to do down our ability as a nation, it is to state a truth about how any redistributive union operates. After all, in receiving more than the average, Scotland is in a group that includes the north-east, north-west, London, Wales and Northern Ireland.

This postwar consensus across the UK was built from the remnants of war. And in the past five years since the start of the economic downturn we have again tried to establish a way to rebuild our economy and our society. It is not a coincidence that this period of disruption has seen a rise in arguments about separatism across Europe, fuelled by the feeling that we can build walls to protect our people from global economic forces.

I know that the prospect of separatism offers little to my constituents in Glasgow, not least because of what I know we can achieve with a Labour government across the UK and what could be achieved in Scotland with a Labour Scottish government. However, the argument goes even deeper than that. The debate about Scotland's future is part of just one argument in a broader debate about how we want to take our country forward. It's a debate about how we respond to the forces that are buffeting our country today, how we make globalisation work for everyone and, ultimately, how we improve the lives and livelihoods of people across our country.

In that respect, this is as much a debate about competing ideas about how we take our country forward as it is a debate about separating Scotland from the rest of the UK. And that's why today's announcement matters to everyone across the UK – because the debate we are having is a threat not just for people who care about Scotland being part of the UK, but to everyone who believes that, to address globalisation, the best response is to bind together, not break apart.