The End of Population Growth

"There has been enormous concern about the consequences of human population growth for the environment and for social and economic development. But this growth is likely to come to and end in the foreseeable future"

This is taken from the first line of Lutz, Sanderson and Sherbov's 2001 'letter to Nature'. They used UN and US Census Bureau to create thousands of simulations in order to find trends in population growth and size and to determine about when our population will stop growing.

source: Lutz, Sanderson and Sherbov (2001)

What the graph above shows is the probability that the population will stop growing before a given date. So for example there's a 90% chance that population growth in the European former USSR will stop before 2050, whereas only less than 10% chance that will happen in Sub-Saharan Africa. In any case what this tells us is that there is an 85% chance that the world population will stop growing by the end of the century. 

The figure below shows when (and at what value) they project the world population size to peak, along with UN projections. They find that the median peak would be at 2070, with 9 billion people, after which it would begin to decline.

source: Lutz, Sanderson and Sherbov (2001)

So the main idea here is: why is everyone worrying so much about population growth when in less than 100 years our population won't even be growing anymore? The natural trend is for our population to peak and then stablise and even decline, ergo, population growth won't really be contributing anymore to environmental issues.

I suppose technically if our population stops growing by 2100, we will no longer be able to say 'right now' population growth is having negative effects on our environment, but that doesn't mean that it's not an issue in 2013 or that having a population of 9 billion doesn't have dangerous repercussions for the Earth systems. A lot can happen in 86 years and we already know (and I've already mentioned) that a lot of the current population that is 'poor' is expected to become a lot wealthier and we know what that means: more consumption. 

Something they did talk about which is worth mentioning here is the social and economic challenges that a stabilising and declining population has, the main issue being aging of course. I'll return to this topic though, it's a really important one because it brings up questions of how much the health of the environment matters, vs the social welfare of the human population, which is a tricky subject and not really the topic of this blog but everything is interlinked so I will no doubt write a post about it.