How Reliable is the World Population Forecast?

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1 ANSWER How Reliable is the World Population Forecast? Short answer Very reliable

2 Let s look at the track record of the UN population experts Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

3 195 They made the first long-term forecast back in Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

4 They said that by the year 000 there would be a little more than billion people Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

5 The common reaction was: That s impossible! Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

6 In 19, they made another forecast Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

7 And one more in Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

8 Now we know the number. Already the very first forecast back in 195 was quite good Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

9 0 In 0, UN experts made this forecast Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

10 01 And in 01, they made another forecast 90 years into the future Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

11 01 Both forecasts predict that population growth will slow down. The difference is how soon it will slow down and at what number it will eventually level off Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

12 11 The UN population experts have a good track record. So the number will probably be somewhere around 11 billion people Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, ; UN World Pop. Prosp. 0 & 01.

13 RELATED QUESTIONS How did Babies per Woman change in the world? Short answer It dropped Throughout history, women on average have given birth to more than 5 babies. But in the 190 s the number suddenly started dropping. Today it's down to less than three. Most likely it will continue to drop down to two or even below. How did the world population change? Short answer First slowly. Then fast. In this short video Professor Hans Rosling shows how the size of the world population has changed over time. From the beginning of agriculture to the industrial revolution the population growth was very slow. Then the population started to grow rapidly because fewer died young. Today, most women have fewer children and therefore the rapid growth will soon be slowing down. World population will most likely stabilise around 11 billion towards the end of the century. How can the world population forecasts be so good? Short answer Births & deaths can be predicted The UN population forecasts can be very accurate. This is because the future population is determined by factors that are quite predictable, namely births and deaths. We know that people grow older, and the approximate death rates of different age groups. The number of adults and old people are therefore relatively easy to predict. It is harder to predict how many children there will be, but knowing the number of adults in reproductive age makes it possible to estimate how many babies will be born.

14 LICENSE This file is freely available under Creative Common Attribution License.0 Which means: Please use it and spread it in any way you want! You are allowed to Remix - You are allowed to change the material and include fragments of it in other works. Spread - You are allowed to make copies, distribute, publish and transmit the material. Sell - You are allowed to include the material in commercial products or services that you charge for. The only requirements are: Trademark - Don't include the word "GAPMINDER" and the logotypes in your products or service, and if you change the meaning of the slides, you must remove the Gapminder trademarks. Attribution - You must make clear to others the license terms of this work and include the citation below. Required attribution: Free teaching material from The Gapminder Foundation is a Swedish not-for-profit organization, independent from all political, commercial and religious affiliations. Gapminder s mission is to fight devastating ignorance with a fact-based worldview that everyone can understand. Gapminder s chairman Hans Rosling is a professor of International Health at the Karolinska Institute, Stockholm, Sweden. For more information visit:

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