The overpopulation argument is seductively simple on face value:
1) The world has environmental problems.
2) People, by and large, cause these environmental problems.
3) Therefore, fewer people = fewer environmental problems.
Campaigns calling for population control - invariably based on projections of human numbers stabilising at around 9 or 10 billion - are becoming increasingly prominent (see Bloom blog 'David Attenborough's born ultimatum').
But when we talk about population control, who are we talking about less of? Many industrialised nations already have negligible or negative population growth, once you've removed immigration and momentum from the equation, so who exactly are we prevailing upon to stop having children?
The main drivers of the projected 'population explosion' are all in the 'developing world' - the Indian subcontinent, China and parts of Africa - with the sole 'developed' exception of the United States. So are we really saying that we've already had all the benefits of industrialisation and a booming population, but you lot shouldn't follow suit. How fair is that?
We are, in any case, terrible at predicting population growth (see Michael Blastland's insightful 'How can a graph be so very wrong?') so can we realistically plan based on our projections? Human populations, like climate, respond to an astonishingly wide range of factors, making them fiendishly difficult to forecast.
We also generally get it wrong when it comes to assessing our ability to feed ourselves sustainably. Take, for example, Paul Ehrlich's highly influential 1968 book 'The Population Bomb', which predicted the deaths of millions due to famine during the 1970s and 1980s. He reckoned without the Green Revolution in agriculture and thus got it spectacularly wrong. He's not the first and probably won't be the last.
Like many seductively simple ideas, the devil of population control is in the detail. It is also arguably the most misanthropic face of the climate change debate, especially when it strays into the morally questionable territory of population reduction.
So not only could our population demands be unfair, they could also be misguided. People are not, by default, bad things to have around. We are much more than lumpen carbon-producing units on the environmental balance sheet. We are creative, intelligent, adaptable and resilient. Who's to say that a couple of billion more people aren't the cure rather than the problem?