New Study Projects World Population of 11B by 2100

vinces99 (2792707) writes Using modern statistical tools, a new study led by the University of Washington and the United Nations finds that world population is likely to keep growing throughout the 21st century. The number of people on Earth is likely to reach 11 billion by 2100, the study concludes, about 2 billion higher than widely cited previous estimates. The paper published online Sept. 18 in the journal Science includes the most up-to-date numbers for future world population, and describes a new method for creating such estimates. "The consensus over the past 20 years or so was that world population, which is currently around 7 billion, would go up to 9 billion and level off or probably decline," said corresponding author Adrian Raftery, a UW professor of statistics and of sociology. ... The paper explains the most recent United Nations population data released in July. This is the first U.N. population report to use modern statistics, known as Bayesian statistics, that combines all available information to generate better predictions.

Most of the anticipated growth is in Africa, where population is projected to quadruple from around 1 billion today to 4 billion by the end of the century. The main reason is that birth rates in sub-Saharan Africa have not been going down as fast as had been expected. There is an 80 percent chance that the population in Africa at the end of the century will be between 3.5 billion and 5.1 billion people.

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[Anonymous Coward]

Ebola or some other virus doesn't wipe out a third of the world population.

No, It Won't

[CanHasDIY]

The number of people on Earth is likely to reach 11 billion by 2100

Nope; before then we'll have a good solid pandemic, or war, or famine, or hey - maybe all three! That will make a significant dent in the existing population.

At least, one could hope :)

Re:No, It Won't

[Anonymous Coward]

The number of people on Earth is likely to reach 11 billion by 2100

Nope; before then we'll have a good solid pandemic, or war, or famine, or hey - maybe all three! That will make a significant dent in the existing population.

At least, one could hope :)

And why would you hope for such a disastrous event when there still exists the unknown of natural sustainability with 11 billion people?

As crazy as that sounds, we're not exactly sleeping on top of each other stacked 15 high these days. You might have a point with food supplies and resources, if we were not constantly being accused of wasting so much food feeding an nation of obese gluttons.

Take the greed of the 1% down a few notches, and sustainability might be far easier than previously thought without tactics like disease or bloodshed thinning the herd.

In before...

[magsol]

...all the comments about "Bayesianism is better than Frequentism" or "Why didn't the authors use this Frequentist analysis?" start popping up. Not that I'm advocating for one over the other, just arguing that they're both tools that are often used for the same nail without realizing that you need to hold them slightly differently for them to actually work the way they're supposed to.

I hope a carpentry analogy is acceptable in lieu of a car analogy.

Not a problem...

[mi]

Vast areas of Earth remain unpopulated. In no particular order:

• American Midwest
• Most of Canada
• Australia's Outback
• Siberia
• Sahara and other hot deserts
• Antarctica — a whopping continent

Sure, some of the above would require some work to make comfortable, but it can be done even with today's technology — by 2100 even an individual (or a family) would convert surroundings to their tastes. And it would certainly be easier, than moving an appreciable quantity of people off-Earth...

Re:Not a problem...

[Xest]

That assumes that all those environments are pointless wastes of space, unfortunately that premise isn't true- those areas of land serve important purpose for example the sands of the Sahara blow across the Atlantic and fertilise the likes of the Amazon rainforest.

A lot of people say "Why don't we geo-engineer the Sahara to make it tropical forest again!" but it becomes almost a zero-sum game, as you grow forests in Africa you decrease the fertilisation of the Amazon and so growth is stunted there in turn.

We can only move into these territories (or even keep expanding in existing ones) if we can find a way to do so without impacting the underlying ecosystem, otherwise we find ourselves with a whole lot of people and not enough resources and you know what that generally means? war - winning side gets the resources.

So it's not just about making an area habitable, or comfortable, it's about doing so in a manner that doesn't have a knock on effect elsewhere - by regrowing Africa into a tropical jungle paradise you'd be slowly pushing ever more of South America into a poor inhospitable desert. Similarly if you start inhabiting Siberia and Antarctica with more human activity resulting in greater melting of these regions you'll simply be flooding coastal regions elsewhere and making them uninhabitable.

Long story short, you cannot make massive changes to large areas of land without there being an impact elsewhere. You can see this on many scales, whether it's the farmers that cleared the forests on the hills of South West England to give themselves more land for crops leading to widespread devastating flooding due to lack of trees to slow water down in the hills, or whether it's something much larger scale as with the Africa/Amazon connection above. For every sizeable environmental change we make there is an impact elsewhere.

For what it's worth, I suspect the place we could most likely inhabit on land with the least impact elsewhere is in parts of the sea but even this would require a lot of care so as to restrict ocean pollution from waste which may damage fish stocks and decrease food. Failing that it's to space we go I guess.

Which isn't to say that there aren't some areas of the planet we can inhabit with little impact elsewhere meaning there is some scope for population growth, but those areas are becoming ever less common and the effects of inhabiting them elsewhere are often subtle making it difficult to know when you have and haven't found a reasonable spot to settle more people. Thus fundamentally it's not simply a case of saying "Hey look that place isn't inhabited, let's inhabit it!" because in doing so you're causing destruction of environments elsewhere where people were inhabiting and now you have to find room for them too.

Of course, I suspect none of it will matter- the rich will live where they desire to live and any knock on impact on anyone else? well they can go fuck themselves, because humans are an inherently selfish species.

Re:Maybe we if stopped giving Africa food

[Rigel47]

Do tell how "the west" is responsible for most of Africa's ills. Last I checked they've mostly been governing themselves for a few generations (exception SA). Shall we blame the Brits for Sunni and Shiia slaughtering each other for hundreds of years too?

Re:Just like bacteria or virii

[Maxo-Texas]

I must be misremembering the universe #.

Here's a link.

http://en.wikipedia.org/wiki/J...

and a quote...

Mouse experiments
John Calhoun with mice experiment.

In the early 1960s, the National Institute of Mental Health (NIMH) acquired property in a rural area outside Poolesville, Maryland. The facility that was built on this property housed several research projects, including those headed by Calhoun. It was here that his most famous experiment, the mouse universe, was created.[1] In July 1968 four pairs of mice were introduced into the Utopian universe. The universe was a 9-foot (2.7 m) square metal pen with 54-inch-high (1.4 m) sides. Each side had four groups of four vertical, wire mesh âoetunnelsâ. The âoetunnelsâ gave access to nesting boxes, food hoppers, and water dispensers. There was no shortage of food or water or nesting material. There were no predators. The only adversity was the limit on space.
John Calhoun meeting Pope Paul VI on 27 September 1973.

Initially the population grew rapidly, doubling every 55 days. The population reached 620 by day 315, after which the population growth dropped markedly. The last surviving birth was on day 600. This period between day 315 and day 600 saw a breakdown in social structure and in normal social behavior. Among the aberrations in behavior were the following: expulsion of young before weaning was complete, wounding of young, inability of dominant males to maintain the defense of their territory and females, aggressive behavior of females, passivity of non-dominant males with increased attacks on each other which were not defended against. After day 600, the social breakdown continued and the population declined toward extinction. During this period females ceased to reproduce. Their male counterparts withdrew completely, never engaging in courtship or fighting. They ate, drank, slept, and groomed themselves â" all solitary pursuits. Sleek, healthy coats and an absence of scars characterized these males. They were dubbed âoethe beautiful onesâ.

The conclusions drawn from this experiment were that when all available space is taken and all social roles filled, competition and the stresses experienced by the individuals will result in a total breakdown in complex social behaviors, ultimately resulting in the demise of the population.

Calhoun saw the fate of the population of mice as a metaphor for the potential fate of man. He characterized the social breakdown as a âoesecond deathâ, with reference to the âoesecond deathâ mentioned in the Biblical book of Revelation 2:11 [1] His study has been cited by writers such as Bill Perkins as a warning of the dangers of the living in an "increasingly crowded and impersonal