WE live in an anything-goes society nowadays. There are very few taboo subjects. Speech and broadcasting is freer than ever and there are scores of comedians and columnists who make a nice living simply by shocking people.

I suppose our acceptance of views and comments that would have had our parents reaching for the off button is a sign of our maturity.

But there are still some topics where we tread carefully, and one of them is the growth and control of world population. It is a subject so awesome and complex that we mostly prefer to put it out of mind.

But we can’t ignore it.

Sir David Attenborough was a recent combatant in this war of words and I suppose if you refer to human beings as “a plague” and food aid as “barmy” – words which just about beg to be taken out of context – you have to count any damage as self-inflicted wounds.

Sadly, these words reinforce the view that people who support population control are well-heeled Westerners who are far too quick to blame people for being poor and hungry – which, incidentally, I don’t think Sir David would ever do.

His case, though, illustrates the difficulty in having a reasoned and calm debate.

The UN’s population division says with some authority that there are seven billion people on the planet – an increase of six billion in the past 200 years. A city that size would occupy the whole of France, but leave the rest of the globe completely empty.

So there’s a case to say we’re overcrowded, and an alternative view that the planet can easily accommodate more.

And how many is more? The UN estimates that by 2100, world population could increase to ten billion. Another projection says 16 billion.

Yet another says the population could decline to six billion. That is because – work this one out – while population rates are increasing, the fertility rate is going down.

Population change will affect countries in different ways. China’s population is predicted to decline. So will Germany’s, yet in Ethiopia the population will increase from 80 million to 145 million by 2050.

Added to this we have the hard-won increase in life expectancy which will see the number of over-60s double to two billion by 2050. Hardly a day goes by in our own rich and resourceful country without dire warnings of this demographic timebomb’s impact on our economy and services. What will it do to those countries where healthcare and social services remain a dream?

Don’t expect easy answers. Family planning can’t be forced on people but education, and support for basic health services, should surely be the foundation of aid packages.

We can’t go on wasting energy and food.

I am sure there is a wise – or at least wellpaid – man somewhere who could explain the logic of using cereals for fuel or ploughing them back into the ground while people starve, but the rationale is beyond me. One fifth of us consume four fifths of the world’s resources and spend most of our time dreaming up ways to get a bigger share of the cake.

That isn’t good for anyone.

With more mouths to feed and fewer hands to bring in the harvest we can’t afford to stand idle.

In the past few days we’ve been asked to imagine what life would be like if the lights went off. That could happen not just here but anywhere in our comfy, complacent world.

But we won’t be able to blame any politician.

It will have been our finger on the switch.