The United Nations has just released the 2012 revision of their world population forecast. Looking at a graph of world population it would appear that forecasting would be relatively straightforward. However, if we look back at how accurate previous forecasts were it is clear that the effort is more difficult than it looks.

An update of world population forecastsFor this analysis we looked back at the UN population forecasts from 1994 and 2000 to see what forecasters were saying the population would be now (in 2010) and how the previous forecasts compare to the most recent forecast for the future. For this analysis we look at forecasts for the total world population, and the populations of Africa, China, India and South America. Just for clarification the UN data for China include Taiwan but do not include Hong Kong.

Based on the most recent update, the world population in 2010 was 6.916 billion. This is below the number forecast for 2010 in 1994 of 7.032 billion but more than the 6.826 billion projected in 2000. It is interesting that world population is rising faster now than was projected in 2000, but slower than the projection made in 1994.

The increase in population growth since 2000 is mostly in Africa. In 2000 when the UN updated their forecasts, the problem of AIDS affected the outlook for Africa. The population in Africa forecast for 2010 stood at 1.069 billion in the 1994 report, but 997 million in 2000. Now the outlook for Africa’s population has rebounded with the most recent update showing the actual number at 1.031 billion in 2010. Over the longer term this assumption about AIDS makes a huge difference. The 2012 update put Africa’s population at 2.393 billion in 2050, almost 400 million more than projected in 2000. Over the next 40 years Africa’s population increases by 132 percent.

An update of world population forecastsThe forecast for population growth in China has declined over the years. In the 2000 UN update China’s population reached 1.462 billion in 2050, 77 million higher than the 1.385 billion in the latest update. In all three of the forecasts evaluated, China’s population declines between 2025 and 2050. Population  growth in China has already slowed to 0.6 percent per year and population peaks in 2030 at 1.453 billion.

India’s population is still rising rapidly. India adds more than 15 million to its population each year, far more than the 8.5 million added in China. In fact India accounts for nearly 20 percent of total growth in world population each year. The increase in Africa accounts for 33 percent of the world total. But the forecast for India’s population has increased over time. The country’s population in 2050 was forecast to reach 1.345 billion in the 1994 UN update, 1.572 billion in 2000, and is now put at 1.620 billion. With India contemplating a policy that could significantly boost per capita consumption for the country’s poor the extra people in the country now and in the future could significantly impact world demand.

Data for South America were included in the analysis just to show what is happening in a less populated, modestly growing part of the world. But even in South America the forecasts have changed significantly over time. The population of the region in 2050 will be 78 million higher than predicted in 1994 but 30 million less than forecast in 2000. The population of the region increases by 28 percent between 2010 and 2050, almost as large a percentage increase as is forecast for India (34 percent).

The data still show that most of the population growth over the next 40 years will be in poor countries. The countries with the biggest increase in population in order are India, Nigeria, Ethiopia, Pakistan, Congo, the U.S., Tanzania, Indonesia, Uganda and the Philippines. These 10 countries account for more than half of the total world population increase over the period.