12 February 2014

Graph of the Day: UN Population Projections for Africa and China

I was using the data above for a piece I'm working on and thought I'd post it up for future reference. The graph shows UN population projections (medium fertility scenario) for China and the continent of Africa.

Africa is projected to surpass China's population in about 10 years, reach double China's population soon after mid-century and end the century with 4 times China's population.

15 comments:

  1. The UN, based on their own figures, have to admit climate change will be beneficial to Africa, keeping a population estimated to be 4 times that of China fed.

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  2. African countries are arriving with a lag to the demographic transition involving a lower level of fertility. However, even if somewhat late, they ARE arriving there, and at an accelerating pace, in tune with the rapid growth observed in a number of African countries during recent years.
    UN projections of population do not take into account other factors besides historical tendencies in mortality and fertility, and have been historically reticent to acknowledge decreases in fertility, thus systematically tending to overstate population growth (for example, no demographic model was able to predict that developed countries would decrease fertility to levels well below replacement, i.e. about 1.2-1.5 children per woman, and to stay there for decades, nor the rapid decrease in developing country fertility outside Africa that has occurred in recent decades). Demographic models do not include independent variables such as economic growth, education, technology or health care progress, but only past trends in demographic variables plus some assumptions about the future that often turn out to overstate population growth.
    Africa population would probably overcome China some years from now, as will probably India, but the future unbridled growth of African population up to 2100 is not to be taken for granted. At least, models should introduce income and education projections into the model, recognizing that income and education affect fertility, and that a falling fertility (for given GDP growth) tends to increase per capita income which in turn causes further rise in education and further decreases in fertility. Only at very high levels of income and education (such as in several European countries) fertility of the native population tends to rebound towards replacement level (some countries are also helped by the higher fertility of immigrants, which offsets the low fertility of natives, as is the case of the US). Bottom line: do not panic; long term population projections are usually exaggerated.

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  3. Would the UN be considered a credible source for any data, no matter the subject? Just saying….

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  4. Does the piece you're working on include GDP per capita projections, energy access projections?

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  5. I'm not really up on this, but I thought I remembered that the best projections had world population leveling off at around 9 billion or so, so I was rather surprised that Africa would be half of the world population. I think the answer is in different assumptions, as laid out by Hector M. #2.

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  6. I gotta say, with all their other projections regarding energy demands/access (globally and on the African continent): Does the UN realize this is their projection for population?

    Just considering the heat riding up the elevator this morning, I bet having 4 Billion extra people in the world by itself can add a little bit to the surface temperature ;-)

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  7. @3. W.E. Heasley: UN historical population figures come from national censuses and estimates, and are generally as good as they can be (for some countries, only guesstimates are available). Future projections are different: they are generated by UN demographers with certain models and assumptions.

    @5. Mike: UN projections are updated every two years. The most recent revsions (2010 and 2012) have modified previous assumptions, which resulted in continued growth of world population beyond 2050, reaching more than 10 billion in 2100 in the Medium Variant. The 2008 Revision presented projections only to 2050, but its assumptions (if applied to subsequent years) would have resulted in stabilization or slight decline of world population in 2050-2100. The key modification concerned projections of fertility (expected number of live births per woman of fertile age, i.e. ages 15-49): the 2006 and 2008 revisions envisaged all countries converging to a level f 1.85 children, which is below replacement, thus ultimately leading to a declining population; the 2010 and 2012 projections assumed that all countries would converge to replacement level, and this implies a long period of positive growth that extends beyond 2100. In my opinion, the particular model of fertility adopted (where countries pass but a short time at levels below replacement) is not realistic: many developed countries have stayed below replacement for decades, and fertility rises slightly just at very high levels of economic and social development (see Myrskylä, Mikko, Hans-Peter Kohler & Francesco C. Billari 2009. Advances in development reverse fertility declines. Nature 460:741). Thus perhaps UN demographers are again overstating population growth, as they often did in the past.

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  8. What Hector M said......
    The projections for Africa are nutty, and are never going to happen.

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  9. According to Google:

    Land area of Africa: 30,221,532 km²

    Land area of China: 9,706,961 km²

    Both have large areas of desert, although Africa's is higher. But China has a much higher proportion of high mountain.

    There's no prima facie reason why Africa can't support 4 billion.

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  10. With a progressive presence of Chinese in Africa, will the population boom be caused by Chinese immigrants or reproduction by integrated families? There have been protests against the communists' population protocol. Perhaps Africa represents an opportunity to reduce the problem set through an emigration relief valve.

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  11. the graph above is actually the graph for temp (red) and CO2 levels up to 2100 that the UN keep hidden but rather than waste the graph they just fitted in some population levels for Africa.

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  12. 85 year predictions aren't worth the paper they should have never been written on.

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  13. Dr. Pielke:

    UN's prediction on population (at least in China) is quite on the Malthusian side. Demographic data (with bad aging structure) from the population census in 2000 (TFR 1.22) and 2010 (TFR 1.18) showed that the peak value is less than 1.4 billion, but UN and the Chinese “Family Planning Commission" denied the data. They used TFR = 1.8 for 2000 and TFR = 1.6 for 2010 as the basis to continue the birth control policy.

    For more on this point you may see the work by Prof. Feng Wang of UC Irvine.

    http://www.brookings.edu/research/articles/2010/09/china-population-wang

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  14. Daniel Xia:

    They're experiencing the same problem with planned reproduction as they experienced with a planned economy: misaligned development. There are other consequences, but I'll stop with this. The outcome of misalignment is well known in the PRC's history. It is a problem in other societies, including America, but with a less devastating effect on the native population. Their foray into large-scale intelligent design schemes has forced a distortion and corruption of natural and social feedbacks, which would otherwise produce a stable population and economy. In America, the worst has been voluntary, but it has forced significant compromises, and corruption of people as they rationalize their choices.

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  15. This is John F. Hultquist: I looked at this graph and thought had the UN been around in the 1870s the red line would be their index of human ingenuity and the black line the volume of daily waste created by that great mover of goods and people, the horse. If one adds all the weight of the UN structures and occupants in NYC, the waste part seems about right.

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