1. Free teaching material for a fact-based worldviewQ1
ANSWER 4
— How Reliable is the World Population Forecast?
Short answer — Very reliable
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Free teaching material for a fact-based worldview

2. World Population Billion people10 8
Let’s look at the track record of the UN population experts. 6 4 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

3. Free teaching material for a fact-based worldview
World Population Billion people 10 8 6 4
They made the first long-term forecast back in 1958. 2
1958
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

4. Free teaching material for a fact-based worldview
World Population Billion people 10
They said that by the year 2000 there would be a little more than 6 billion people. 8 6 4 2
1958
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

5. Free teaching material for a fact-based worldview
World Population Billion people 10
The common reaction was: “That’s impossible!” 8 6 4 2
1958
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

6. Free teaching material for a fact-based worldview
World Population Billion people 10
In 1968, they made another forecast. 8 6 4
1968 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

7. Free teaching material for a fact-based worldview
World Population Billion people 10
And one more in 1978. 8 6 4
1978 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

8. Free teaching material for a fact-based worldview
World Population Billion people 10
Now we know the number. Already the very first forecast back in 1958 was quite good. 8 6 4 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

9. World Population Billion people10 8
In 2010, UN experts made this forecast. 6
2010 4 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

10. World Population Billion people10 8
And in 2012, they made another forecast – 90 years into the future.
2012 6 4 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

11. Free teaching material for a fact-based worldview
World Population Billion people 10 8
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.
2012 6 4 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

12. Free teaching material for a fact-based worldview
World Population Billion people 11 10 8
The UN population experts have a good track record. So the number will probably be somewhere around 11 billion people. 6 4 2
1950
2000
2050
2100
Sources: Nico Keilman "Data quality and accuracy of United Nations population projections, “; UN World Pop. Prosp & 2012.
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Free teaching material for a fact-based worldview

13. Free teaching material for a fact-based worldview
RELATED QUESTIONS
Throughout history, women on average have given birth to more than 5 babies. But in the 1960’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.
Short answer — It dropped
How did Babies per Woman change in the world?
Short answer — First slowly. Then fast.
How did the world population change?
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.
Short answer — Births & deaths can be predicted
How can the world population forecasts be so good?
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.
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Free teaching material for a fact-based worldview

14. LICENSE
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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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Free teaching material for a fact-based worldview