The problems with the number



Ask any population activist, or any journalist who has ever written a story about world population, and they will tell you that by the year 2050 world population will grow to 9.2 billion people. This singularly quoted 9.2 billion number comes from the United Nations - specifically; the 2006 revision of the World Population Prospects done by the United Nations Department of Economic and Social Affairs Population Division - and it is accepted by all as the only authentic projection of world population.

Well…maybe not by all, because I believe that the real number, when we arrive at 2050, will be much higher, more likely in the 11 - 13 billion range.

Think about this and try to imagine how the various current debates about global climate change, peak oil, species extinction, etc., would be altered if a number of 12 billion was used as the authentic projection for 2050 instead of the 9.2 billion number. Perhaps then, the current complacency about this so-called "overpopulation" problem would be replaced by a true sense of alarm.

So - you say - how can one individual writing on a little website dispute the entire United Nation's department of professional demographers? And in fact, let me disclaim any expertise in this area - I'm not a demographer, or even an expert in population projections. But, if you give me a few minutes (by reading below) you can draw your own conclusions.


First, some information about the UN projections:

There are two basic components in any population projection - fertility, and mortality (duh). In the 2006 revision of world population, I believe the UN is substantially inaccurate on both of these components.

1 - The UN is overly optimistic in their projections for a declining worldwide fertility rate.

2 - The UN's mortality projections do not consider unexpected events (like a cure for cancer) leading to dramatic increases in life expectancy.

In order to avoid the possibility of being wrong, the UN actually makes four basic projections (and seven other specialized projections, based on various assumptions about the AIDS epidemic and alternative migration patterns). These four main variants (as they call them) are titled: low, medium, high, and constant fertility. The 9.2 billion number is the medium variant.

Interestingly, The UN makes no claim as to the relative likelihood of any of these four projections (low - 7.8 billion, high - 10.7 billion, constant-fertility - 11.8 billion) being the correct one. So, with a range of four billion in their projections, they are at least assured of being in the ballpark with one of them. What is clear though, is that the world of journalism has assumed the medium variant is the right number. I would guess, simply because it has been titled "medium".

All four UN projections use the exact same mortality model (this will be discussed in more detail below), therefore the only difference between these four variants is in the fertility projections.

And the only difference between the high and low fertility variants, compared to the medium projection, is that they have added a factor of .5 to the fertility rates for the high variant, and subtracted .5 for the low variant. In other words, the model moves exactly the same over time, and by country, for all three variants.

Therefore, these really aren't three different models. They are exactly the same model, except for the half-a-person subtraction or addition. The UN offers no logical reason for this .5 addition or subtraction - i.e., why not .7 or .33? It was simply a way to make one bigger and the other smaller. They could just as easily have said - our model shows a population of 9.2 billion, give or take a couple of billion.

The fourth model is the constant-fertility variant. As the name implies, this model keeps fertility constant over time, as estimated by each country for the period of 2000-2005. The constant-fertility variant indicates a population of 11.8 billion in 2050, and would yield something close to 24 billion by 2100. Scary.

The model for the medium variant (remember, it's the same model as the high and low variants, except that.5 thing), as published on the UN's website, does not disclose exact country-by-country, year-by-year, fertility forecasts, but it does disclose many of the basic assumptions they have used. Several of which I would consider curious.


The problems with the UN's projections of fertility

First of all, their fundamental assumption is that all countries will experience a decline in fertility as time goes on. This is based, of course, on the historical trends in the developed countries, primarily in Europe, over the last half century. It assumes several things - primary among these assumptions is that even the less developed countries will embark on an un-interrupted march toward increasing prosperity and education (the universally accepted driver for declining birth rates) over the next 41 years.

In fact they make the assumption that all nations will move to the specific fertility rate of 1.85, with most nations getting there by 2050, and the rest getting close.

To this end, they make the following statement: "
…in countries where fertility has stalled or where there is no evidence (emphasis mine) of fertility decline, fertility is projected to remain constant for several more years before a declining path sets in." In other words - even in countries where there is no evidence of fertility decline, they project it will begin happening in a few years, and then follow the exact same path as the developed countries. There is clearly no scientific reason to make this claim.

To get to this 1.85 level, one of two things needs to be present. If declining fertility is a product of increasing prosperity and increasing education levels (this is the commonly accepted reason), then this assumes all countries will experience increasing prosperity and education getting to (or close to) the level of the most developed countries. In light of the current state of the world's economy, this seems wildly optimistic. Or, conversely, even with a constant (or possibly deteriorating) standard of living, these less developed countries will somehow still experience a dramatic drop in current fertility rates - also wildly optimistic.

Apparently demographers were taken by surprise during the last few decades by the sudden drop in fertility in the developed western world, and have vowed not to let that happen again. So they use the developed western world as a model for
all of the world.

As stated earlier, I'm not anything close to being a demographer, or any kind of expert in this field, but common sense tells me that many parts of "the rest of the world" may not behave like Germany with regard to fertility rates. The influences of culture and religion will likely dominate their viewpoints on reproduction far more than the influence of a slightly increasing standard of living.

Then, there is the ultimate fertility "wildcard".

I know that specific "unexpected" events cannot be included in these scientific projections (though the UN does play around with several AIDS scenarios, including one where a vaccine is available to everyone by 2010), but there is one event that could have a dramatic impact on fertility, and should be understood.

China's one-child policy is, without question, the most successful population management program in the world, and the UN projections show that in dramatic fashion. China's 2005 population of 1.312 billion is the world's largest, but look at what the UN projects for growth by 2050 - only 96 million more! By contrast, India will grow by 524 million during the same time frame and even the US (starting at a base of one-fourth of China's population - 300 million) will grow by approximately 135 million (according to the US Census Bureau) during that same period. In the next 40 years, we in the U.S., will add more people to the world than China!

But now, with the dramatic rise in capitalism in China, coupled with the aging, and likely toppling, of their current ruling class, we could very easily see a major modification of the one-child policy in the near future. If I was a betting man, I would put the odds of that happening before 2020 at close to one hundred percent.

Then, with the likely initial explosion of births from the current pent-up demand, plus an "echo" boom twenty to thirty years later, China's population could easily balloon by hundreds of millions, possibly half a billion. This very likely scenario is not considered in any UN projections.


The problems with the U.N.'s mortality projections

"Follow the Money" the Watergate informant "Deep Throat" once famously uttered. In that spirit, tell me - where is the vast majority of the money going these days - in trying to decrease fertility, or in trying to increase life expectancy? I expect the ratio might be as high as ten-thousand to one in favor of increasing life expectancy.

Drug and treatment research for cancer, diabetes, heart disease, etc., is a huge industry in the developed western world where life expectancy is already high. Genetic research in all of these areas is progressing very rapidly, and many feel that significant breakthroughs are imminent. In the less developed countries, major efforts are underway to mitigate the impacts of Malaria, Aids, and other diseases that currently so affect those areas.

And the UN can't have it both ways, if these less developed countries are going to experience such a significant increase in their standard of living that they will reduce their fertility rates to, or close to, 1.85 (the same as the developed world), then their life expectancy should shoot up significantly as well. I'm guessing here - but my expectation is that the UN mortality projections for the less developed world do not move that dramatically.

The UN projections regarding mortality are straightforward - here is what they say:
"Mortality is projected on the basis of models of change of life expectancy produced by the United Nations Population Division. These models produce smaller gains the higher the life expectancy already reached. The selection of a model for each country is based on recent trends in life expectancy by sex".

I understand that the UN demographers cannot pick a date when, say, a cure for cancer becomes available. Yet, given the massive amount of money and effort being expended, the likelyhood that breakthroughs in cancer, heart disease, AIDS, etc., will occur in the next ten to twenty years is very high.

And while most of the beneficiaries of these breakthroughs will be of post-reproductive age, they are still boots on the ground - people who have to live somewhere, have to eat, and who will assist us in consuming the earth's resources.

Some may argue that unexpected events may also affect mortality in a negative way - i.e., asteroid impact, new diseases, etc. - and while that is possible, the odds of a major die-off event happening in the next fifty years are far, far less than, for instance, a breakthrough in cancer research. And besides, an unforeseen apocalyptic event of any magnitude makes this discussion moot - and so it is pointless to consider it in this context.

And so…

Because the UN is too optimistic about falling fertility rates, and not optimistic enough concerning life expectancy breakthroughs, and because it ignores the likelihood of China modifying its one-child policy - then, it appears to me that the oft-quoted, medium variant, projection of 9.2 billion people on this earth by 2050 is significantly understated.


Some pure speculation on the reasons why the UN underestimates population growth

The fundamental assumption in the world of demographic fertility projections is that fertility will decrease as a result of increasing prosperity and education. And, it is a safe assumption that every government of every country in the UN espouses those same goals of increasing prosperity and education for their people.

The UN is made up of representatives of those governments (not necessarily of the people), and so it would be hard for any government representative to accept a projection that showed that their country would be stagnant or declining in these important aspects. They would adamantly disagree. Hence, the quote (earlier) that the UN projected declining fertility even in those countries where there was no evidence of fertility decline.

Because of their sheer numbers, the UN is, in many aspects, dominated by the second and third world countries. I would imagine there is strong internal political pressure to not offend this dominant block.

Think of what might transpire if the UN actually projected a population of 12 billion in 2050. The world would be forced to face the problem and take hard action. So, It would be far more palatable for the UN membership to instead project a much smaller number and avoid upsetting the status quo.

To think that the UN population division is immune to this kind of internal politics would be naïve.


I'll leave you with one last factoid to think about:

U. S. Population projections from the U.S. Census Bureau: 1996 - 2008:

In 1996 they projected U.S. population in 2050 would be 392 million
In 2000 they projected U.S. population in 2050 would be 402 million
In 2004 they projected U.S. population in 2050 would be 420 million
In 2008 they projected U.S. population in 2050 would be 439 million

Do we see a trend here?


Copyright "The Population Elephant" and Kurt Dahl March, 2009 - All rights reserved.

(Return to home page)

Send any comments or reprint requests to
suggestions@populationelephant.com


Return to Population Elephant homepage