A growing population is a constant worry when living in a closed environment with limited resources. But… is the population really going to grow? Below I talk about projections provided by various sources such as UN and census.
50 years
Census.gov used a simple formula[1] to reach an estimated 9.8 billion population by 2050 while the UN reached a range with a low 7.4 billion and a high of 10.6 billion. A research team from the Autonomous University of Madrid, publicized an interesting study in which they predict the world population will stabilize by 2050 by using the fertility rates provided by the UN they were able to create a model that showed that the population will stabilize and decrease over the span of 50 years.
source: Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat(2000). World Population to 2300. New York: United Nations.
100 years
The UN has provided projections based on fertility variants. The 2010 projection shows an outlook of a little over 10 billion in 2100 with a high 27 billion and a low of 6 billion.
300 years
Further projections are included in the UN’s earlier publication of 2000. With the population being at well below 6 billion due to the difficulty in maintaining the replacement of parents (each couple producing 2 children).
source: Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat(2000). World Population to 2300. New York: United Nations.
*Of course none of these estimates include scenarios such as natural disasters or epidemics.
Predicting the future population is just that : a prediction. Though these predictions are detailed and backed by billions of dollars there is no way to know the population in 2050, 2100 or 2300 until . Although pyramids are becoming pillar in form in developing countries[2], nothing is set in stone.
[1] r(t)=[((p(t+1)-p(t))/p(t)]*100
t = year
r(t) = growth rate from midyear t to midyear t+1
p(t)= population at midyear t
[2] See previous post.
Issues in Physics and Society 
A lot of what we talk about in class, and as a society, deals with ‘if population continues to increase…’ we’ll run out of X, Y and Z. Some of the projections you use show that population may actually decrease but my question is, is that enough?
Using the IPAT formula (Impact = Population x Affluence x Technology), we see that decreasing population will decrease impact but only if affluence and technology fail to increase. The average income, globally, is expected to increase by a factor of 10, and technology continues to increase at an alarming rate that even a severe decrease in population would not necessarily compensate for.
There’s also the fact that most governments don’t want to see their populations dwindling – especially if the government’s function by having younger generations supporting older generations. In hopes of creating a babyboom, developed nations like Japan and Germany, have offered incentives like paid childcare leave or even a ‘baby bonus.’
This turns into a NIMBY issue. Everyone knows a smaller population would use less resources and create less waste, but no one (except in extreme cases, like China) is willing to impose, or even to seriously suggest, plausible solutions to population growth.
Unfortunately decreasing population does not necessarily mean that there is a proportional decrease in waste…certain people produce more waste than others and therefore waste production in relation to population would be more accurately measured by an average of waste production in specific locals totaled to a sum value. This idea is the basis to the issue you bring up. Thanks, I never thought about it like this. Rather, I never thought about it much at all.
I wonder how affluence and technology are measured because that seems like something important to consider.
Also – random side note. One inadvertent mechanism for population control is global food and water shortages. If we were to create conditions of economic equality and equalize access to life’s necessities, I think population growth would get pretty out of control (unless education and birth control also spread in concert with money and mitigated these effects).
I am of course not saying that inequality is good, but, seeing that overpopulation and energy consumption are such huge problems, it is worth noting that equal access to food, water, health care, etc, could exacerbate the existing problem – which really just makes finding well thought-out solutions more important. Also, by creating the conditions for economic equality, we may create a world where almost everyone wants to be able to consume the way that Americans and others consume now – clearly, that world would be wholly untenable. Economic equality (the focus of my research) thus also needs to be sought in conjunction with sustainability measures.
Oh, I guess my first reply never went through. This was it (a response to Rebecca wondering how affluence and technology are measured):
I’ve been wondering how the measurements for this IPAT formula work as well, specifically affluence – I mean, wealth is all relative, right? For someone to be “rich”, someone else needs to be “poor”. The way it is measured in the formula is GDP/person, but… like, as a world, we could all just say tomorrow that 1$ is now $2, so GDP would double… I guess the important part of the formula is determining how much energy is consumed per person, which is certainly related to GDP.
From there, we see that an area with limited “technology” (in terms of energy-extraction and usage) will impact the world much more than an area with advanced technology in this sector. Growing an economy without improving the efficiency of your technology will lead to a greater global impact.
It is not necessarily true that equality will make everyone want to consume as much as Americans. Perhaps other cultures gaining equality can have a positive influence on the wastefulness of our American culture…on my own wastefulness…
Some inequality is good. Money really does motivate people to work and that is a good thing. We need people to do all jobs and every part is significant. The tiniest screw in a car engine missing deems the entire engine ineffective.
Access to resources does not necessarily have a direct relationship to the number of children. Some of the poorest people have large quantities of children. I am taking about those who live off of welfare here in the U.S. or those in Africa who have many children. Access to condoms and forms of birth control would probably be more effective as you mentioned, and for that to flourish basic necessities must be met first.
Yes…I don’t fully understand the IPAT formula…at least not yet!