Using Loglet Lab, we have fitted logistic curves to the total fertilty rates for some of the regions/countries of the world. More on the implementation can be found at Human Population Dynamics Revisited with the Logistic Model: How Much Can Be Modeled and Predicted?
The figures are available as a pdf file for easier printing and viewing. [Download].
We observe that, with few exceptions, the total fertility rates (TFR) are decreasing. In the developed nations of the world TFR is heading to low levels below the replacement rates (~2.1), while in most developing nations and least developed regions the TRF remains well above replacement rate.
Using these Fertility assumptions we have estimated the population changes for the next few decades up until 2050. Obviously, beyond 20-30 years, uncertainty grows large due to possible changes in fertility, mortality, and migration. The forecasts were made to the year 2050 using the PDE Population Development Software1, essentially a spread-sheet model that calculates populations (male and female) grouped in 5-year cohorts in 5-year time steps. The start year is set at 2000.
We have assumed constant Mortality set at the Life Expectancy value at year 2000 (UN Data Sets2). As most populations experience increasing longevity, this makes our forecasts conservative (low). However, some countries have experienced falling longevity (mainly for males) due to HIV(Southern Africa) or factors such as alcoholism, smoking and stress (Russia).
Migration has been ignored for now as reliable data to establish trends are hard to obtain.
Click to view the AGE-SPECIFIC POPULATION PYRAMIDS AS A PDF
For ten nations and regions (China, India, Africa, Europe, Italy, Yemen, Russian Federation, Japan, Brazil, United States), wes have prepared figures contrasting population pyramids for 2000 with the projections for 2050.
To better visualize these population changes we have used Motion Chart, a gadget available on Google Docs. You can select countries/regions of choice to explore the contrasts.
The default X-axis is Time, Y-axis denotes the Total Population. The Colors of the Graph lines are assigned based on the Total Fertility Rates.
Click on Settings (little icon on the bottom-right)
Make sure that
Move the arrow to 0% again for ease of viewing.
To Zoom In
To Zoom Out
Click the 'Zoom out' link above the zoom thumbnail in the right panel (or) Right click anywhere within the chart and choose the 'Zoom out' from the drop-down .
It is best to take a snapshot of the screen using any screen capture software and then print the images.
A set of slides summarizes our observations, "Implosions, explosions: Population trends to 2050 based on a logistic model of fertility with all factors held constant"
1PDE Population Projection Software. Laxenburg, Austria: World Population Program, International Institute for Applied Systems Analysis (IIASA), 1994.
Available at: http://www.iiasa.ac.at/Research/POP/pub/software
2United Nations, Department of Economic and Social Affairs, Population Division (2007). World Population Prospects: The 2006 Revision. CD-ROM Edition - Extended Dataset in Excel and ASCII formats (United Nations publication, Sales No. E.07.XIII.7).
Please address any comments/suggestions to: firstname.lastname@example.org