Page last updated at 12:37 GMT, Thursday, 19 November 2009

Migration v ageing population - a tricky trade-off

Too many or not enough? Population projections are useless for telling us what will happen, but by showing what might, they reveal a tricky trade-off, says Michael Blastland in his regular column.

What do you do given a choice between two demographic time bombs?

Graphic of men going up steps
The UK's population is predicted to rise from 61m to 71m by 2033

That's not a flattering description of what's happening (because remember, you - if you live in the UK - and me, we are those time bombs), but this is how many see it.

On the one hand, there's the fear of an explosion in numbers, driven largely by migration, creating a new Birmingham every Tuesday, or whatever the calculation happens to be.

On the other, there's the ageing population, leaving about three of us to look after and pay the pensions of teeming millions in walking frames.

I might have exaggerated slightly, there, but the issues are real.

These trends are seldom considered together, but both were raised by figures released a few weeks ago .

Our slideshow allows us to compare them and suggests that every outcome will leave someone worried or unhappy.

Click through the slides to see the effect on the population of different assumptions about migration. The shaded area on each graph shows how it compares with the previous graph.

Graph One
Baby boom works though middle age
Sides of pyramid are less sloping than in the past, it looks thin at the bottom (fewer young) and wide in middle (working age baby boomers and migrants).
Graph Two
Pushing up and out
Migration continues at 2006 rates. Pyramid swells up and out (boomers grow old, migrants and their children fill out lower down).
Graph Three
Thinner lower down
Slightly lower migration. A bit thinner in the middle and bottom (fewer young and working aged). But growth at the top is still there.
Graph Four
Fatter all round
Same shape, but wider most of the way up, especially noticeable among working aged and young (the bottom and middle).
Graph Five
Top heavy
Pyramid becoming a column. Fewer working aged and young, nearly 100,000 fewer births than any other projection, but still the growth at the top.
BACK {current} of {total} NEXT

This population pyramid data was prepared for Go Figure by the Office for National Statistics (thanks folks).

Note that these are projections, not forecasts, and simply extrapolate from data that is probably already changing. Note too that the "no net migration" projection doesn't mean no migration, it just means no more people coming in than going out.

If you think there's not much change here, think again.

For example, by 2033 under the first projection (slide b), there would be about 150,000 more 66-year-old men and about the same number of extra women (nearly a 50% increase), with about a couple of hundred thousand more at almost every age into the 90s.

Either the country grows more crowded, or possibly less rich than it could be

The high migration projection adds about 100,000 to 150,000 people at every age up to about the 80s compared with the low migration projection.

Compared to which, the "no net migration" removes about 200,000 people at almost every age up to about 60.

What the slides suggest is that these two possible futures create a choice, and help us to see something of its scale. If we restrict migration, it might seriously worsen what's known as the dependency ratio of elderly to those of working age.

If we allow or encourage migration at recent levels, it would probably bring a big increase in a total population of increasingly diverse origin.

Changing world

So either the country grows more crowded, or possibly less rich than it could be.

You might say that we should just put up with the latter until a smaller number of children works its way through to old age, when the whole population will begin to shrink, and that this would be a good thing in the long run. But it still creates about a 50-year difficulty.

Now you can see the potential effects, what would be your choice? Is that choice changed by the data?

Numbers, even the wrong numbers (since all projections are wrong, as I've noted in the past ) can help us make better sense of change, but they can't tell us what our political values should be.

So perhaps what's most usefully confirmed here is something we all know but often forget in the heat of the argument, that the world is dynamic.

There is no stable state of affairs we can arrive at that solves all our problems. The large-scale effects of all our individual choices and prospects might be, on aggregate, those that no individual would choose.

Makes you wonder if all our lives would be so much easier if it wasn't for, well… if it wasn't for us.

Below is a selection of your comments.

People get so tied up in the way future immigration may change the makeup of the UK that they ignore the economic reality. It's good to remember that the only constant in life is change!
Richard Spurr, Leics.

What you don't comment on is in the steady increase of retirement age. As the aging population becomes healthier and more able to continue working longer, the number of pensioners who need support from the working population should, in theory, remain roughly the same thus meaning no need to keep importing people to pay taxes. This would then mean no population growth but just simply extending people's working lives (which probably isn't a vote winner!).
Andy, Guildford

What you appear to be ignoring is a tendency among some economic migrants to come here and work for a few years, before returning "home". How does that affect your figures?
P Gain, London

Seems another option would be no net migration combined with an increase in the retirement age - this would mean the reduction in those aged 20-65 could be offset by those aged 65-70 (say) carrying on working, and there would be no need for migrants to fill jobs.
Charlotte, Cambridge

Print Sponsor


Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit


Sign in

BBC navigation

Copyright © 2019 BBC. The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific