No-one is taking migration seriously. We need to start.

We are playing political games over a migration crisis we could manage comfortably while paying no attention to a migration crisis to come. That one will sink us - if we don’t act now.

The fake immigration crisis has turned into a real political crisis in the UK. It is a serious threat. And yet none of this has anything much to do with the real immigration crisis, a crisis that is so monumental that our shrunken Western politics cannot compute.

The problem is surprisingly simple; we are an over-populated world in an era where large sections of the globe are becoming uninhabitable because of climate and war. The only options for many is to move or to die. That is already leading to some of the biggest mass migration of the modern era and this problem is only just beginning.

Usually in my columns I try to think of big issues that aren't being properly discussed and I try to find some kind of solution – or at least to sketch out the shape of a solution. I'll take a half-hearted shot at it at the end of this piece, but the case I really want to make here is that we're so far from even absorbing this problem that it is pointless talking about steps to address it.

I want to tell a tale of the future to give you a sense of it. It is 50 or 60 years from now and Scotland is a divided society. There are those who were born here and there are those who think it's their right to be here because they can't live where they used to. Their former homes have been destroyed. They need somewhere to live. Scotland seems empty. That'll do.

There are millions of them. They arrive in an uncontrolled, unplanned way. They overwhelm the housing system, public services start to topple over. The local economy is not geared up to serve this sudden influx. It breeds resentment and violence.

A run-down hotel houses the most desperate. Some are so disorientated they turn to violence and crime. This creates a backlash. At first the Scots try to be accommodating, but gradually some people start to lose patience. The racist graffiti becomes more and more common. People start talking about males aged between 18 and 40 as 'fighting age'.

Immigrants are attacked. As housing struggles to cope, more and more Scots start to ask why they're having to sacrifice for people from another country. We understand their homes have been destroyed and we feel bad about that, but why is that our problem?

Gradually we get anti-immigrant politics emerging. The violence gets worse. Protests outside those migrant hotels escalate. Suspicion is everywhere – people are accosted in the street and the locals demand they speak, that they reveal where they're from. And that phrase, that awful phrase, goes from being unacceptable to being a mainstream part of life in Scotland.

“Fucking English Out! Fucking English Out!”

Like I say, we feel bad that Scarborough, Blackpool, Hove, Skegness and Hull were all completely destroyed by rising tides. And perhaps we should have done something when this started as a trickle, when people started being unable to get house insurance. Perhaps if we'd begun a mass housebuilding programme, perhaps some new towns in the highlands.

But it's too late now. We just don't have anywhere to put English refugees. We don't have jobs for them. Yes we've had an influx of English GPs, but that is only helping to relieve Scotland's shortage. There are calls for a points-based system. Eventually English people start to look for new places to go. Scotland is a hostile environment.

And that story is a mere trifle when you look at the global scale. Hundreds of millions of people are abandoning their homes, from the equator up to southern Europe. The flow of desperate people goes way beyond biblical. There has never, ever been a movement of human bodies like this in our history and we have no way to deal with it.

This is what drives me nuts about liberals and their 'open borders, all immigrants are good' mantras. Congratulations, virtue signalled. Now how on earth does the planet deal with this? Every sane step we could have taken we rejected. When it became clear that climate change was an existential threat we should have acted. We didn't.

When the corporate exploitation of the global south made sustainable local responses impossible in hollowed-out nation states, we should have said no, we need the global south to be able to prepare for what is coming. We did no such thing. In fact we ladled on further sovereign debt – because we could.

Right across Europe we knew 50 years ago that we'd undermined our own societies by turning property speculation into a get-rich-quick-scheme and that unless we reverted to a housing market which was genuinely affordable and was creating housing supply to match demand, things would get worse still. We're about to allow big business to use AI to destroy what is left of the social contract.

When we bombed countries to see if that would help it, unsurprisingly, made everything much worse. When we sanctioned them and starved them we did the same. We could have not done any of these things, but we like doing these things because we're in the safe zone. For now.

“I repeat one more time at the top of my voice – a more rational species would be trying to stop this happening...Sadly, we do not appear to be that species. ”

Civil war doesn't really cover what this will all lead to. It's a bigger and more fundamental sort of conflict and we're leaving it all to those who come after us. It is quite easy to argue that climate change is the most irresponsible thing any society of humans as ever done, but it might be in the resulting migration crisis that we see the true vision of hubris, red in teeth and claw.

I could keep going. This is going to coincide with the collapse of a lot of long-standing food systems and will be taking place against the backdrop of increasingly volatile weather. Whether there will be widespread democratic systems still standing to address all of this is not something we can take for granted now. This is a serious problem.

In Scotland we have choices because we're very, very lucky. We're going to lose St Andrews, Falkirk, Grangemouth and the Clyde Estuary up to about Hillington, but most of Scotland's coastline is pretty high. We have lots of spare land, boundless energy resources and (subject to no collapse in the Gulf Stream) a mild climate with good food-growing conditions.

That gives us options. One is to build a wall with England and militarise our coastline. Make no mistake, a Fortress Scotland approach is not only feasible, it is rational and could respond to the crisis. What it isn't is moral, or particularly reliable. Assuming we need to trade with the rest of the world, we can't lock the doors completely.

We could plan and manage migration if we started early (the fore-mentioned new towns and housebuilding), but we'd almost certainly need to set a cap. There's only five million of us – more people commute into Cairo each day than that.

We could push a global debate. In the way that it is the low-lying Pacific islands which have been the moral outriders for climate change because they will be the first to suffer, Scotland could stand up now and say 'don't start eyeing our resources – you're not all coming here so you better do something'.

In fact we could lead in suggestions. I see no real option other than engineering our way out of this. I think this is seismic enough that we need UN-mandated sanctuary cities. We need to make unliveable land liveable. We can do that – if we are committed. A well-designed, well-engineered new city in the Sahara would be zero waste, would recycle every millilitre of its water, would have streets covered in vegetation to reduce heat load, mass outdoor hydroponics systems to provide food...

These could be staging posts, or final destinations, or some combination of the two. While Common Weal is very much about 'repair what is there', retro-engineering cities is really difficult and in many places it will be easier to design from the ground-up than to adapt the cities we have. And of course, if we make these slums it is just a whole new kind of a crisis, and potentially an even more dangerous one.

Another option is to think strategically not about what will be lost but what will be opened up. The most fertile and desirable patch of land in Europe will one day be Siberia. It may seem a long way off, but populating the vast expanses of Siberia may one day be European humanity's best shot.

I suspect that this will kick off a new round of debate and discussion about over-population generally. This would of course all be easier if there were fewer of us, and in the future that may be a reality that we have to live with. The other response is increasing density of population centres.

Is this all much of a life for our grandchildren? Perhaps not, but we're driving them to that place whether we know it or now. I repeat one more time at the top of my voice – a more rational species would be trying to stop this happening not through 'net zero' policies and 'ceasefires' but through carbon negative policies, pacifism and society-building. Sadly, we do not appear to be that species.

None of this is really speculation. What we are seeing in terms of migration in the UK is only the very tip of the iceberg. The internal migration in the global south dwarfs what we face just now. In fact far from the migration crisis purely being a result of the Syrian civil war (and the Western propensity to bomb brown people periodically), in fact the Syrian civil war was in large part caused by mass internal migration resulting from climate change.

All of this is real and, on the path we seem determined to continue on, inevitable. I'm delighted that there is a big pushback on the anti-immigrant sentiment in Britain. Farage's scapegoating turns my stomach. But our 'migrants welcome' banners are just another form of sticking our heads in the sand.

Migration wasn't a real crisis, but it is now and it will grow and grow in scale. We did this. Unless we take it seriously, it will swallow us whole.