The places where population is growing fastest — sub-Saharan Africa, rural China and Bangladesh — have virtually no carbon emissions, and pitiful food consumption rates. The gap is so huge that to be responsible for as many gas emissions as one British person, a Cambodian woman would need to have 262 children. Can we really sit in our nice homes, with a fridge-full of food we will mostly chuck away and an SUV in the drive, and complain that she is the problem?
Of course, there's only so many people we can fit on the earth- and, you know, feed.
But if this is a problem, is there a solution that isn't abhorrent? Some people seem to reach instinctively for authoritarian answers. The government of China has bragged that its "greatest contribution" to the fight against global warming has been its policy of punishing, imprisoning or sterilising women who have more than one child. Some environmentalists — a small minority — eye this idea jealously.
There is a far better way — and it is something we should be pursuing anyway. It is called feminism. Where women have control over their own bodies — through contraception, abortion and general independence — they choose not to be perpetually pregnant. The UN Fund For Population Activities has calculated that 350 million women in the poorest countries didn’t want their last child, but didn’t have the means to prevent it. We should be helping them by building a global anti-Vatican, distributing the pill and the words of Mary Wollstonecraft.
So we do need to reduce our population growth to something manageable, but improved social justice, security, and women's rights take care of that pretty neatly. For instance here in Canada, where women can be pretty independent, with (mostly) good access to birth control, and a relatively comfortable economic situation, we have a below replacement fertility rate (1.53 per woman). Reproductive rights are a very important part of the puzzle (Unless you're China) - just one more reason we must keep fighting that fight. As I wrote previously:
Give women more choices and they won't have as many babies - they may work outside the home, delay marriage, and use contraception. Children are expensive and less of an asset in industrial, urban societies as opposed to agricultural societies. Wealthier populations tend to also be healthier, which means less infant mortality (which generally correlates with having fewer babies).
It seems that population growth is inversely proportional to the degree to which a society is egalitarian, urbanized and economically secure. You can play with this yourself using Gapminder. Just press "play" to see how the indicators change over time.
Here, correlated with total fertility rate, is Life expectancy at birth. As life expectancy increases, fertility rate decreases. This one shows under 5 mortality rate. This one relates total fertility rate to the percentage of girls who complete primary school. Again, the trend is clear. Similarly, an increased Urban population also correlates to a lower fertility rate. Finally, increased income per person means fewer babies born.