April 14th, 2011 | Posted in Population Basics
by Carl Haub, senior visiting scholar
The United Nations Population Division has released preliminary results of its biennial series of population projections for the world’s countries for the 2010 revision. The projections are expected to be finalized later this month.
While the global population for 2010 — 6.873 billion — is slightly lower than estimated in the 2008 revision (6.909 billion), the projected population for 2050 is now higher at 9.295 billion compared with the previous 9.150 projected in 2008. That can also be compared to the 2050 population of 9.485 billion on PRB’s 2010 World Population Data Sheet and 9.256 billion in the International Data Base of the U.S. Census Bureau.
The 2010 UN projections differ from the previous series in two significant ways. First, the projection horizon has been extended to 2100, quite far into the future. Second, the UN no longer assumes a uniform “ultimate” level of the total fertility rate (TFR) for all countries, such as the 1.85 level in its Medium Variant. Instead, multiple possibilities for each country’s TFR are projected with a probabilistic method based on fertility trends for the 1950-2010 period. Then, the median path of those “tracks” serves as the projected TFR for the Medium Variant series. The High and Low Variants, however, will be projected as in the past. Those variants have used an “ultimate” TFR of 2.35 and 1.35 for all countries, respectively.
|Projected Population in 2100, United Nations 2010 Medium Variant|
|8||Congo, Dem. Rep.||212,000|
The projected population of sub-Saharan Africa (SSA) in 2050, the world’s region with by far the largest potential for population growth, is now 1.963 billion, up from 1.753 in the 2008 UN projections. But, since the projections now run to 2100, we can now see beyond mid-century. By 2100, the UN projects that SSA would total an eye-popping 3.4 billion, nearly four times its present size and still be growing by 0.7 percent per year, adding 2 million annually at that time!
Projections, of course, are based on such assumptions. If the assumptions prove false as time goes on, so will the projections. It has always been traditional in demography to assume that higher birth rates in developing countries will do what they did in developed countries – decline to two children per woman on average or less. When that happens, if that happens, and how it might happen is a matter of conjecture. In the case of SSA, the projections assume that the TFR in Uganda would decline from about 6.4 in 2005-2010 to 3.1 in 2050. Similar assumptions apply to other countries. The UN has always pointed out that such assumptions tacitly assume that the use of family planning will spread continuously, resulting in fertility decline. Time will tell.
There’s many a slip between the cup and the lip but the new UN projections provide a fascinating look into the possible population world of 2100. In the table above, we can note that India would be the world’s largest country in 2100 after its population peaks in size in 2060 at 1.72 billion; Nigeria would be third behind China and number four would be Tanzania, with a population equal to that of the U.S. today, up from about 45 million at present.
When the UN releases its final results, they will be summarized here. For more information, watch this episode of Distilled Demographics, which explains how population projections are made and the assumptions involved in determining projections: