The Uncertain Future of Global Population Numbers

An anonymous reader writes "The question of global population is a pretty crucial one; how many people will there be in ten years? In forty? The New York Times notes research done by a group called the Worldwatch Institute, research that concludes world population figures are too fluid to make any sort of educated guesses. Childbearing populations combined with severe resource shortages in some parts of the world make pinning down a global headcount unfeasible for ten years from now, let alone out to 2050. The article continues beyond its original borders, as well, with commenters in the field of population studies noting we don't even have a good grasp on how many people were alive in 2007."

Comments

Re:Carrying capacity overshoot

[IamTheRealMike]

What few people realize, is that the earth can support more people than what is commonly called the "carrying capacity" - temporarily.

You state that as fact, but as far as I know the concept of "carrying capacity" is not defined or even studied. Whilst it makes intuitive sense that there must be some limit, it also makes sense that this limit would itself be fluid - changing with the march of technology and changes in living standards. I've never seen anybody calculate a carrying capacity for 21st century Earth, especially not scientifically. People who use the term invariably assume it must be lower than our current population - how much lower is usually pulled out of thin air.

It becomes clear that the world just can't go on like that forever. It probably can't even go on like that for more than a couple of years. The green revolution has been made possible by oil and gas and both are getting much more expensive each and every year now.

Your list of societies is disingenous - you list a primitive, fully collapsed society like Easter Island right alongside Great Britain, which last time I lived there imported half its food because you can't grow strawberries there year round, not because it was about to collapse. Britain could feed itself tomorrow simply by converting some of its farming capacity from meat production to cereal production.

Also, the green revolution was triggered mostly by the development of nitrogen fertilisers, weed killers and crop varieties that could handle being treated with them. Although we use hydrogen from natural gas to make nitrogen fertilisers today, you can produce it using electrolysis without problem. And whilst it's true that today farm machinery is mostly gasoline powered, that's something independent of the green revolution. If you haven't already read it, I suggest checking out Stanifords Food to 2050 for a data-based analysis of whether the green revolution can be sustained.

And no, it's not a "global problem" like the one-worlders want us to believe. Some countries will be able to manage well (like Iceland which with almost zero immigration and geothermal energy plants is well prepared)

Only a small proportion of Icelands power comes from geothermal. Most of it is hydro. Iceland has much bigger problems than electricity anyway - there's basically nothing there, and whilst it has energy in abundance the economy is mostly based on industrial fishing. Once the fish stocks are exhausted, there'll be little left to sustain it.

I would be very surprised if there will be more than 3 billion people living in 2050.

Ah ha, I knew it. As soon as I read the term "carrying capacity" I was waiting for the ass-pulled number. Why 3 billion? Why not 2, or 4? Or 100 million? I don't see any particular constraints on slow population growth - it's been boringly linear for most of the 20th century in most developed countries, and in large parts of Europe is going to head sharply downwards soon due to natural demographic trends anyway. Whilst places like Africa or Chian might get miserable, Africa is already miserable and there's no obvious reason why in the long term China would see different population trends from other developed countries.

Re:Easy question, easy answer

[rjhubs]

You are very mistaken, this is an extremely complicated question, moreso than TFA states. In 1798, Thomas Malthus started worrying about population growth saying because we were growing at an exponential pace. This thought continued and Hardin used at as one of his main points in his famous paper the Tragedy of the Commons. But, as this became a more important question, we have gathered more data and it turns out our assumption that population growth would stay exponential was wrong.

Here midway on the page are some graphs of current population estimates and global growth rates. You can see that global birth rates have already declined. And even the high end estimates for global population start to taper off. Some even predict global population will decline.

The reasons for this decline are also complicated, but the two most prevalent explanations are first, the advent of birth control finally allows women to control when they have children. And second, and more importantly, look at this picture a growth rate of 0 means the population of that country is staying at a constant level (for every birth there is a death), negative means population decline, >0 means population growth. Notice that most of what we call "industrialized" nations are at a maintenance level or are in population decrease. That includes China and India, the two most populated countries in the world. While most the population growth is just in Africa and parts of the Middle East and South America(and note the south africa and egypt don't have growth). The reason for all this is explained as, as a society gets more 'industrialized' the need for families to be larger decreases. While in places where farming is necessary for survival, the incentive to have more children (free labor) is high. Its not that Africans don't have access to birth control, its that its more beneficial for them to not use it.

So the prevailing theory today is that as Africa gets more industrialized, their population growth will go down and global population will stabilize. We could argue about whether or not Africa will get industrialized, but I think in absence of very strong evidence, we have to believe the more industrialized a nation gets, its population growth approaches 0 or even negative.