Implosions, explosions: Population projections to 2050 based simply on a logistic model of fertility
with an interactive gadget, The Fertility Explorer

Jesse H. Ausubel, Cesare Marchetti, and Smriti Rao

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?

More developed Regions
Least Developed Countries

Eastern Africa
Northern Africa


Eastern Asia
 Hong Kong
South-Central Asia
Western Asia


Eastern Europe
 Russian Federation
Northern Europe
Southern Europe
Western Europe

Central America
South America

 United States of America

 New Zealand

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.

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.

Visualization using the Fertility Explorer

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
Non-Selected Items
Move the arrow to 0% again for ease of viewing.

To Zoom In

  1. Put your mouse in the chart area.
  2. Hold down the left mouse button and draw a rectangle over the items you want to zoom in.
  3. Release the left mouse button.
  4. In the menu that pops up, select '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 .

To Print
It is best to take a snapshot of the screen using any screen capture software and then print the images.

Some Macro Trends

  1. World population increases. Globally absolute growth is similar in Asia and Africa, but steepest growth in Africa (tripling); Latin America and Caribbean grow while Europe declines.
  2. Developed regions will experience a steady decline while less developed countries will experience a steeper growth.
  3. Within Africa, Northern Africa grows more slowly than sub-Saharan Africa.
  4. About 2020 India surpasses China as the most populous nation. TFR in China is already below replacement level (~2.1) while in India TFR levels remain above replacement in 2050.
  5. Among Asian countries some countries with steepest growth are Afghanistan, Iraq, and Yemen, which quadruples from about 20 to 80 million. If Afghanistan maintains its historically high fertility, it will cross 100 million.
  6. Some already quite large countries continue large absolute growth in spite of declining fertility owing to a momentum of youthful populations. Some examples are Turkey and Iran.
  7. Northern Africa roughly doubles in numbers, of whom more than 150 million are Egyptians. Ethiopia approaches 200 million.
  8. Meanwhile, populations of European countries plummet. Germany, Italy and Spain lose about 1/3 of their native populations. Smaller European population also shrink in size
  9. In South America the countries with larger native American populations grow faster, a phenomenon we dub as "reconquista", as the conquistadors are diluted.
  10. In North America, the US grows for a couple of more decades and then declines as does Canada.
  11. Overall, even in a world of slow global population growth, the populations of some nations explode while others implode. Many changes will soon occur in the population rank of nations. The steep gradients imply tremendous international migrations, which in turn change national populations - and cultural identity.

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:

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).

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