WS MoreOrLess: Population explosion?

Summary

More or Less – “Population explosion?”

Podcast: More or Less
Host: Tim Harford
Date: September 30, 2013
Episode Theme: A critical investigation into widely shared statistics and claims about world population growth and, in a lighter segment, the global population of redheads.

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Episode Overview

Tim Harford leads this episode by fact-checking a recent statement made by the well-respected broadcaster and naturalist Sir David Attenborough regarding global population growth. The show investigates the veracity of longstanding fears about a “population explosion,” compares expert forecasts using the same datasets, and explores why there’s so much disagreement in population projections. In a second, more lighthearted portion, the team debunks a claim about Scotland being home to nearly a fifth of the world's redheads.

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Major Discussion Points & Insights

1. Fact-Checking Attenborough: Has World Population Tripled?

• Claim: Since Sir David Attenborough began making programmes 60 years ago, the global population has tripled.
  • Analysis:
    • In 1950, world population was about 2.5 billion.
    • In 2013, it was well over 7 billion (a bit under three times more).
  • Conclusion: Claim is “close enough” to true.
  • Quote:
    • “Yes, it is. Or close enough. In 1950 … about two and a half billion … 63 years later … well over 7 billion. That’s a little shy of tripling, but it’s not far off.” – Tim Harford (01:55)

2. Out of Control? Competing Forecasts for 2100

• Attenborough’s Implication: The world population is “increasing out of control.”
• UN’s Current Projection: World population to be “fewer than 11 billion” by 2100 (~50% increase from today).
  • If actual historical trend continued (tripling every 60 years): ~40 billion by 2100, so UN estimate reflects much slower growth.
  • Significance: UN’s projections are a base for many other forecasts (energy use, economic modeling, etc.).
• Alternative View – Sanjeev Sanyal (Deutsche Bank, Global Strategist):
  • Thinks UN’s forecast is too high.
  • Key Reason: Fertility rates in many parts of the world are below replacement levels (Europe, Japan, China, Brazil).
  • He says:
    • “…[UN models] are generating their population growth with huge increases in population of, you know, small countries like Nigeria … from 150 million to almost a billion by the end of the century.” (03:29)

3. Alternative Population Trajectory

• Sanyal’s Model:
  • World population will peak around 2050 at 8.7 billion, then decline to 8 billion by 2100.
  • Reasoning:
    • More aggressive impact from urbanization
    • Adjusts for gender bias in big countries (e.g. China & India won’t have enough women of childbearing age in the future)
    • Criticizes UN’s assumption of fertility rates converging to replacement rate, as this is not seen in any country that's experienced sharp fertility decline.
  • Quote:
    • “I have probably accounted more aggressively for things like gender bias in countries like China and India … another thing … is that in the long run, [the UN] assume that all fertility rates converge towards a replacement rate. Now, this is a very odd assumption…” – Sanjeev Sanyal (04:51)

4. Why Such a Difference? The Challenge of Projections

• Both use the same census data (2010), but different assumptions.
• Massive consequences: Even small differences in projected fertility rates compound over decades.
  • UN’s own range for 2100: less than 7 billion to almost 17 billion.
  • Summary:
    • Projections have a huge margin of error, and forecasts can vary wildly depending on underlying assumptions.
  • Quote:
    • “…making these long term forecasts isn’t an easy task. We really don’t know what population will be in 2100 because even very small changes to fertility rates can have a huge impact decades down the line.” – Tim Harford (05:34)

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5. Bonus Debunk: Are a Fifth of the World’s Redheads in Scotland?

• Claim heard on BBC (via the Ginger Pride March): Scotland is home to 19% of the world’s redheads.
  • Origin: Sean Hitchens, a Canadian comedian, “just got a bit confused” during an interview; mixed up percentage of Scots who are redheads with world share.
  • Quote:
    • “Oh, gosh. Oh, I'm misleading the people. I am very sorry.” – Sean Hitchens (07:15)
  • Actual Estimates:
    • About 10% of the UK are redheads, possibly a bit higher in Scotland.
    • Worldwide, 1–2% have red hair (approx. 70–140 million globally).
    • At most, Scotland could be home to about 1% of the world’s redheads—not 19%.
  • Quote:
    • “So Scotland is home to perhaps at most, 1% of the world’s population of redheads.” – Tim Harford (08:43)
• Memorable Moment:
  • Tim’s playful remark: “That would be 6 million incredibly hot people in the UK as a whole, and half a million of those in Scotland. Maybe, maybe more.” (08:13)

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Notable Quotes & Moments

• On how population trends affect everything:
  • “The UN population growth projections might not be at the forefront of Sir David’s mind, but they are the basis for all kinds of other forecasts. For instance, about energy use or even corporate profits. No wonder they’ve been scrutinized.” – Tim Harford (02:32)
• On confusion in redhead statistics:
  • “Also, I’m a ginger, so I’m 10 times more likely to make up a statistic.” – Sean Hitchens (07:40)
• On projection uncertainty:
  • “We really don’t know what population will be in 2100 because even very small changes to fertility rates can have a huge impact decades down the line.” – Tim Harford (05:34)

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Timestamps for Key Segments

• 00:18: Introduction & Sir David Attenborough’s claim
• 01:49: Population tripling analysis
• 02:55: UN projections and Sanjeev Sanyal’s alternative view
• 03:29: Critique of UN projections
• 04:07: Sanyal's forecast and rationale
• 05:34: Why population projections are so difficult
• 06:48: Switch to redhead population claim
• 07:15: Sean Hitchens’ admission of error
• 08:04: Actual stats on redhead population

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Conclusion

This episode of More or Less punctures the idea that population growth remains “out of control,” showing instead that projections vary widely based on different (and sometimes unproven) assumptions about fertility trends, cultural shifts, and demographic quirks. In classic More or Less style, the show also unmasks a throwaway statistic about Scottish redheads, reminding listeners to treat exuberant numbers in the news with a healthy skepticism—and a sense of humor.

Transcript

[BBC Announcer]

Thank you for downloading from the BBC. For details of our complete range of podcasts and our terms of use, go to bbcworldserveys.com podcasts

[Hannah Barnes]

this is the short edition of More Or Less, first broadcast on the BBC World Service.

[Tim Harford]

Hello and welcome to More or Less on the BBC World Service, the programme which investigates the numbers in the news and. And in life. I'm Tim Harford. This week we dare to fact check none other than the broadcaster and naturalist Sir David Attenborough. Yes. No one is safe from the firm thwack of our slide rule. This fellow's been feeling it too.

[Sean Hitchens]

I am very sorry. I'm very sorry.

[Tim Harford]

But more of that later.

[BBC Announcer]

First, Sir David, we just shut our eyes to the fact that the world population is increasing out of control. I mean, since I first started in making programs 60 years ago, the human population has tripled. And we don't look at this fact in the face. There is a serious problem ahead of us.

[Tim Harford]

Sir David Attenborough being interviewed on BBC Radio recently. But something worries me about that. It seems to conflict with something broadcast elsewhere on the BBC by a slightly less renowned voice. Birth rates have been falling around the world. World population looks like it's going to stabilise. We have serious environmental problems. It's not at all clear that overpopulation is one of them. Dear me. I appear to have fallen victim to one of the classic blunders. The most famous is never get involved in a land war in Asia. But only slightly less well known is never go in against Sir David Attenborough. Well, let's start by looking at Sir David's historical claim.

[BBC Announcer]

Since I first started making programmes 60 years ago, the human population has tripled.

[Tim Harford]

Is it true? Yes, it is. Or close enough. In 1950, around the time Sir David was starting his broadcasting career, there were about two and a half billion people in the world. 63 years later, and the latest estimates of world population put it at well over 7 billion. That's a little shy of tripling, but it's not far off. So let's move to Sir David's next claim. Is the world's population increasingly out of control? If world population continued to triple every 60 years, in accordance with Sir David's experience, it would be almost 40 billion people. That's 4,0 billion by the end of this century. But the latest United nations projection is that we will have fewer than 11 billion people. The rate of population growth has slowed dramatically, although, of course, 11 billion people is still 50% more than we have today. The UN population growth projections might not be at the forefront of Sir David's mind, but they are the basis for all kinds of other forecasts. For instance, about energy use or even corporate profits. No wonder they've been scrutinized by the

[Sanjeev Sanyal]

likes of this chap Sanjeev Sanyal. And I'm Deutsche Bank's global strategist.

[Tim Harford]

And as Sanjeev pored through the UN's figures, he thought that something was odd.

[Sanjeev Sanyal]

Unfortunately, when I looked at them, I discovered that they were almost certainly wrong about it.

[Tim Harford]

So the UN predicts that population growth will slow enormously. Now, Sanjeev didn't think their forecast was too low. He thought it was too high.

[Sanjeev Sanyal]

If you look at the fertility rate, which is the number of babies that a woman has over the course of her life in very large parts of the world, those fertility rates are now below what is needed to replace the population. Much of Europe, Japan, large countries like China, even Brazil. If you look at the UN's own numbers, you will discover that they are generating their population growth with huge increases in population of, you know, small countries like Nigeria, where they expect population to grow from 150 million to almost a billion by the end of the century.

[Tim Harford]

Let's just run through what your forecast actually is.

[Sanjeev Sanyal]

In my model, the world population would actually peak around 2050 at 8.7 and decline to about 8 billion by the end of the century.

[Tim Harford]

But while Sanjeev believes the global population will peak around 2050, if we look purely at birth rates, we'll stabilize, he says, in just the next 15 years, we'll see a bit more growth overall because of the fact that we're living longer. So let's summarise what we've got so far. The UN predicts that the world's population is going to grow by around 50% over the next 90 years. Yet Sanjiv Sanyal thinks it will barely grow at all. They're both using the same data, which comes from national censuses in 2010. So what explains the difference of nearly 3 billion?

[Sanjeev Sanyal]

I took into account two or three things which I think are inadequately reflected in the UN. One is the effect of urbanization. I have probably accounted more aggressively for things like gender bias in countries like China and India. They aren't likely into the future to have enough women of childbearing age. Another thing that the UN does, which I think is quite awkward, is that in the long run, they assume that all fertility rates converge towards a replacement rate. Now, this is a very odd assumption because we have not seen any country where fertility rates have declined very, very dramatically, to have seen them drift back up to the replacement rate.

[Tim Harford]

So what does the UN say? Unfortunately, they didn't want to comment without first speaking to Sanjeev Sanyal, but they did explain that making these long term forecasts isn't an easy task. We really don't know what population will be in 2100 because even very small changes to fertility rates can have a huge impact decades down the line. The UN's own predictions offer up a huge range from less than 7 billion to almost 17 billion by 2100. Plenty of room for disagreement now from global population in general to the global population of my favourite kind of person. The Ginger Pride March in Edinburgh, Scotland, last month. The first of its kind. I have to confess an interest. I do have a penchant for redheads. I even married one. According to the BBC website, Scotland is said to be home to almost a fifth of the world's redheads. Hmm, that seems like a lot. Or as loyal listener Mark Hagen put it, implausible. Well, Hannah Barnes, you've been looking into

[Hannah Barnes]

this for us and I've traced the origin of this mighty statistical claim all the way back to a BBC radio interview with Sean Hitchens, a Canadian comedian and the organiser of the Ginger Pride March.

[Sean Hitchens]

It's a great opportunity to bring together all the redheads in the country that holds 19% of the world's population of redheads.

[Hannah Barnes]

Now, Sean admitted to me that he just got a bit confused during the interview and got his words muddled up.

[Sean Hitchens]

Oh, gosh. Oh, I'm misleading the people. I am very sorry. The number of redheads, the percentages, nobody really knows the exact one. And then there was somebody from Glasgow saying it was 19% in just the population of SC.

[Hannah Barnes]

So what happened? You were doing a flurry of interviews and you got the 19% of Scotland confused with the world.

[Sean Hitchens]

Yeah, it must have been in confusion. Also, I'm a ginger, so I'm 10 times more likely to make up a statistic.

[Hannah Barnes]

But actually, the online team have admitted that while they hadn't given it much thought at the time, on reflection, it does seem implausibly high. And they've now taken the 20% reference out of the story.

[Tim Harford]

So we know that a fifth of the world's redheads are unlikely to be living in Scotland. Do we know the correct figure?

[Hannah Barnes]

Well, we don't really. It's estimated that about 10% of the UK are redheads and the proportion in Scotland could be a little bit higher than that.

[Tim Harford]

Wow. So that would be 6 million incredibly hot people in the UK as a whole and half a million of those in Scotland. Maybe, maybe more.

[Hannah Barnes]

Tim. Tim.

[Tim Harford]

Sorry, I was miles away.

[Hannah Barnes]

Now, most estimates put the number of redheads at somewhere between 1 and 2% of the total world population, so that would be between 70 and 140 million.

[Tim Harford]

So Scotland is home to perhaps at most, 1% of the world's population of redheads.

[BBC Announcer]

Yeah.

[Hannah Barnes]

And that's still a respectable amount. Northern European nations do have a greater proportion of redheads than anywhere else in the world.

[Tim Harford]

Well, thank you, Hannah. And that's it for this week. If there are any numbers you'd like us to take a closer look at, do please email us. Our address is more or less BBC.co.uk and you can also sign up for a free download of our programmes at our website, bbcworldservice.com moreorless

[BBC Announcer]

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