The world at seven billion

Lots of people

The United Nations estimates that on Monday 31 October the world's population will reach seven billion. But how accurate is this figure?

Not only is the world's population supposedly reaching seven billion today, the charity Plan International has anointed a girl born in India as the seven billionth.

In reality, things are much less clear.

The UN's population estimates chief, Gerhard Heilig, describes it as "nonsense" to suggest anyone could pinpoint where the seven billionth child will be born.

And he says the UN recognises that its own figures come with a 1-2% margin of error. Today's population could actually be 56 million higher or lower than seven billion, Mr Heilig says.

"There is a window of uncertainty of at least six months before and six months after the 31 October for the world population to reach seven billion," he told the BBC.

Start Quote

You are always going to be essentially guessing… We will never have a true, definitive figure”

End Quote Professor Mike Murphy London School of Economics

The UN Population Division website adds that no-one can determine the date with an error margin smaller than about 12 months, as even the best censuses have "inevitable inaccuracies".

"In fact, due to very poor demographic statistics in a significant number of developing countries the uncertainty may be even larger."

The UK census of 2001 illustrates the problem. The population had been thought to be about 60 million, while the census showed it was closer to 59 million.

"The British figures were revised by more than 1% in 2001 and that's in a highly developed country," says London School of Economics professor, Mike Murphy.

There are plenty of other countries, he says - Nigeria for example - where recording systems are far less accurate, and some countries that have not held censuses for decades.

One child

According to some experts, the UN has jumped the gun.

The US Census Bureau says the most likely date the world population will reach seven billion is between March and April next year.

Births in China

The UN estimates fertility (the average number of children born to a woman) using census data, surveys, vital registers compiled by national statistical offices - and, in countries where fertility statistics are controversial, other sources such as immunisation data.

A large number of data sources are used to estimate fertility in China, including vaccination studies and school enrolment ratios. The UN says fertility estimates for China are "very controversial", in China itself as well as in the rest of the world.

Sergei Scherbov of the Vienna Institute of Demography, meanwhile, says there is a 95% probability that the figure will be reached between January and July 2012.

Earlier this year, he and two colleagues published a paper arguing that the seven billion figure was most likely to arrive in 2012 or 2013 - and was almost as likely to occur in 2014 as in 2011. But since then, he says, new figures have come in that make 2012 more probable.

"People have no idea how many of us are here," he says, modestly.

Mike Murphy agrees. "As you can never get a true figure to compare, you are always going to be essentially guessing… We will never have a true, definitive figure," he says.

Out for the count

No census for more than 25 years:

  • Afghanistan
  • Angola
  • Burma
  • DR Congo
  • Eritrea
  • Faeroe Islands
  • Iceland
  • Lebanon

Census data not received by the UN

  • Dutch Caribbean
  • Lebanon (last census 1932)
  • Somalia
  • Uzbekistan
  • Western Sahara

Source: UN

China illustrates one kind of problem. While it conducts well-organised censuses, the one-child rule means that births could be under-recorded.

Mr Scherbov believes the average number of children born to a woman is about 1.4, but the UN used a figure of 1.7 between 2000 and 2005 and 1.64 between 2005 and 2010. That means the UN could have overestimated the population of China by several million, he says. By the same token, Mr Scherbov might have underestimated it by this amount.

The UN's reason for naming a symbolic date as seven-billion day is to draw attention to the speed of population growth, with less than 13 years having passed between the six-billion and seven-billion milestones.

"It can focus attention of people all around the world on global population challenges," says Mr Heilig.

Plan International's goal in picking a girl born in Uttar Pradesh as the seven billionth member of the world population is to draw attention to sex-selective abortion - the practice of aborting female foetuses in countries where male children are prized.

India is also the country with the highest predicted population growth for 2010-2015 - 135 million compared to 80 million in China.

The charity knows of course, just like the UN, that the number seven billion is approximate.

One of its campaigns is designed to ensure that more children are properly registered - as otherwise they have no proof of identity and "no legal existence" - and it cites estimates that 51 million newborns go unregistered every year.

Ultimately, does it matter if the seven billion figure is 1-2% out, or more?

Not really, says Mike Murphy.

"It's not in the end a figure that people use to make specific decisions. It may inform the context in which these decisions are made, but it's not a figure used in decision-making," he says.

The figure plays a part in the debate about the world's ability to grow enough food to feed its growing population. But if population figures are uncertain, Professor Murphy says, this is even more true of food production figures.


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  • rate this

    Comment number 105.

    Oh those darn statistics...I'm here and I refuse to feel guilty. There I said it...I hope all of us just have a great day. Stay out of bed though!

  • rate this

    Comment number 104.

    There are only so many on the planet at this time because billions of souls have purposely incarnated in order to experience the Apocalypse, the Great Shift of The Ages, that is about to occur (21.12.2012). This will wipe out our individual and collective Karma in one fell swoop and greatly advance the race spiritually, though most of us will then occupy the 4th Dimension.

  • rate this

    Comment number 103.

    The problem is people having lots of children. Having two children only replaces the parents but having six/seven (like many 3rd world countries do) means you're increasing the population by about 400% if all children survive and now that medicines are better more children that would die are surviving meaning the population swells. I for one am probably only going to have 2kids -I don't want more.

  • rate this

    Comment number 102.

    Roll on the asteroid!!!!

  • rate this

    Comment number 101.

    My niece was the 3rd born child in the UK of 1996 at 3 minutes past midnight. No-one knows at the point whether the UK population had increased or decreased that day as there may have been more deaths than births and vice versa (excluding immigration and emmigration from the equation). So the idea that one can predict when the world reaches 7 billion living peeople is absurd.

  • rate this

    Comment number 100.

    Don't worry about the figure.Just worry about what,we humans achieved so far in order to keep the population happy.No matter health problems are reduced and technology has stepped up.Also we try to feed our selves better food.Now only if all of world governments improve their morallty. All government members keep their promises and only think of the service to humanity.

  • rate this

    Comment number 99.

    re93-laughing man

    why should I pay for kids that are not mine?especiallky to feckless dole loving girls who have no intention of ever working?phase out the dole to the long term and make them take what ever minimum wage job that is out there which they will be unable to do as they are useless.

  • rate this

    Comment number 98.

    Anyone reading their history will know what is coming - The developed world will be overwhelmed by the others, and we will enter a new dark age. It's all in the numbers and demographics and it's inevitable. No one will profit, what is left will be worthless..and it will all start over, just as before.

  • rate this

    Comment number 97.

    there is no worse human being than a subsistence farmer,especially in the amazonian region.uneducated and destroying the planet,an awesome contribution to the species

  • rate this

    Comment number 96.


    You can't get personal about this. Yes, the children will pay the price. That is the fault of their parents for having too many of them. Sometimes you have to be hardhearted and look at the woods, not the individual trees.
    Don't you mean 'You can't be human about this'? If people are just wood to you, would you be so heartless if your family was affected?

    Darwin would be proud

  • rate this

    Comment number 95.

    The world has far too many people. I'm not sure what the solution is but nature will solve the problem for us - food and water will become scarce and much more expensive and we all know what parts of the world will then have their popluations thinned out.. not the west certainly...

  • rate this

    Comment number 94.

    Don't worry...there is nothing Mother Nature isn't able to correct or put into balance. Hmmm, come to think of it, maybe we should be concerned.

  • rate this

    Comment number 93.

    @85. Brontosaurus

    But that doesn't mean it can't be phased out does it? We could stop paying child benefit (& put their parents in shared accommodation) to all children born from 9 month's time. Then there is no further financial incentive to have a child.
    Explain that to the under privileged children who inevitably grow up in these deliberately inhospitable conditions that you want to create.

  • rate this

    Comment number 92.

    Malthus was wrong many years ago when he said we would never be able to handle our resources with our population, how wrong he was? Again we will find new resources to deal with the ever expanding population.
    Looking at the DTM some MEDC's are already in 'stage 5', and britain are creeping closer to this stage,this possibly meaning a decreasing population? We must ensure LEDCS move into stage 3.

  • rate this

    Comment number 91.

    We focus on the wrong thing. Population is not the issue, even food growth is not the issue (several statistics, even those by UN, show that more food than needed by current and upcoming populations is always grown/harvested). The real problem is inhumanity and greed. Why should we "waste" the food by sending it free to the starving populations? I guess it is "morally hazardous".

  • rate this

    Comment number 90.

    In any case, there's no need to worry, the UN are fully aware of the coming Apocalypse whereby Mother Earth will quite naturally re-set the balance as we reach the culmination of a 26,000 year cycle and the Harvesting of the planet occurs. This has also been revealed by the Master Alchemist, Fulcanelli, in his expert de-cyphering of the Cross of Hendaye. Prepare to meet thy maker!

  • rate this

    Comment number 89.

    As the world's population hits 7 billion any moment now, how much has really changed since 1950? Are some of us growing faster than others? See the numbers for yourself; 1950-2011 comparison of death rate, oil production, gender distribution, and other interesting metrics, with relevant articles and visualizations.

  • rate this

    Comment number 88.

    None of the world leaders is duly concerned about 7billion count.

    Cameron is only interested in soundbites and waffles and is out of his depth in just about everything else.

  • rate this

    Comment number 87.


    Thank you. I'm back to the theme I was banging on about last week I'm afraid, but I think it it the real root of the problem, not the overall number of people per se.

  • rate this

    Comment number 86.

    I wouldn't pay too much attention to the hype.Europe, Japan, & other greying nations should worry about their dieing/ageing populations instead.


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