The UN has decided to announce that on October 31, 2011 the Earth’s human population will pass the seven billion mark, up from the six billion that was designated on December 5, 1998. The United Nations Population Division Agency is the main organization that estimates global population. Every two years, their report attempts to piece together surprisingly fragmentary national census data and demographic surveys to arrive at a global estimate. As a geographer, I have long been interested in these reports, and in all aspects of population change and distribution on the earth.
The UN report is subject to a variety of interpretations, but the main news story has been that a revised methodology projects a global population of 10.1 billion in the year 2100, driven most notably by continued rapid population growth in Africa. This will be a call to arms for population planning programs to increase funding targeted in Africa, along with a new round of debate over the long term sustainability of seven billion people.
The numbers reveal mostly positive news for those concerned about population growth and hoping for a leveling off of population (achievement of zero population growth). First, the aggregate global estimates from 1950 to 2010 show that the rate of global population growth peaked in 1969 at 2.12% per year, and has now declined to 1.15% per year. This means that population growth has been slowing down for the past 42 years.
In addition, the absolute annual increase in population peaked in 1988 at 89.63 million and has declined to 78.152 million in 2010. The overall dynamic is a deceleration toward a leveled-off population this century, with some uncertainty as to whether the peak will be eight, nine or ten billion persons.
We are going from a preindustrial world of a half billion people to a post industrial, urbanized one of seven to ten billion with a global economy hundreds of times larger than the one in the year 1800. Seven to ten— is it too casual to give or take three billion? The difference is not as large as it sounds, since most human activity is concentrated on ten percent of the surface.
That's because three quarters of the Earth’s surface area is covered in ocean and ice, and of the dry land, sixty percent of that consists of tundra, deserts, boreal forests and other lands that have very low population densities. As a result, the difference between a world of 7 billion and one of 10 billion is 350 persons per square mile compared to 500 per square mile of settled land. To put the difference in perspective, look at the densities of France, at 296 per square mile, compared to that of Italy, at 521 per square mile. Passing the seven billion mark, or hitting 10 billion, doesn't call for some fundamental reckoning, or indicate that we've reached a carrying capacity ceiling.
Still, given that UN numbers are estimates, how accurate are the projections for Africa? Table #1 shows the 2010 estimates for the five regions of Africa, and the 2050 and 2010 projections. While East and West Africa combined represent 9 percent of global population and land area, this last frontier of population growth is interesting. The estimates indicate dramatic growth from 1950 to 2010. Population in North, South and Middle Africa as a group have peaked, while East and West Africa are still accelerating. (The other 91 percent of the globe is 80 percent of the way to the UN’s population peak in 2058 and is basically done with population growth.)
The dynamics of global population change are becoming focused on East Africa and West Africa, the two regions which together comprise about forty percent of the land area of Africa. With the rest of the world experiencing a mix of modest population growth and decline, East and West Africa are projected to experience 94 percent of future global population growth. Even with a more likely scenario of a leveling off at 1.523 billion rather than going on to a very large 2.14 billion, East and West Africa will still represent the largest demographic change story of the 21st century.
Do East and West Africa have some demographic similarities with China and Latin America back in 1960? If so, as has been seen around the world, fertility declines from 6 to 2 children per mother will happen much more quickly than the UN 2011 projections suggest. Given that African real economic growth of 57% has been robust in the last ten years, including a 29% gain in real per capita income, there is evidence that the continent is slowly emerging out of a poverty trap. Africa is also rapidly urbanizing, and demographic surveys conclusively show a big difference in the fertility rates of women living in urban areas as opposed to rural ones. East and West Africa represent a very interesting final chapter in modern population growth, with the challenge to use land and fresh water efficiently and protect significant wildlife resources, while potentially becoming an economic powerhouse later into the century.
The story will be interesting and important to follow. In the next forty years, East and West Africa, along with South Asia, will be the big population growth centers, while the rest of the world will increase very slowly. Even with dramatic economic growth, urbanization, and a doubling of population in East and West Africa in the next few decades, the global population could very well level off at 8.8 billion rather than 10.1 billion.
Back to the estimates themselves: The UN pieces together a global story from a set of data and estimates from countries with infrequent censuses. Table Two shows official national census estimates for 31 countries, which represent about 60% of the global population. Most of the census results are coming in below UN projections.
Assuming that the rest of the world’s nations that have not conducted recent censuses have similar overall projection problems, one could infer that the actual population is at least one percent lower than the UN 2011 estimates. If we just assume the UN population growth rates for 2010-11 are accurate, and project these 31 country census results forward to July 1, 2011, we get a population of 6.9 billion people. We would then estimate that the world population would hit 7 billion in October, 2012.
So why is the UN declaring October 31, 2011 as the day of 7 billion? While nobody knows what the true world population is, perhaps the UN should err on the side of accuracy… and put off this announcement until 2012. A delay would increase the probability that we actually have crossed that symbolic threshold, something for all people on earth to reflect upon.
Ron McChesney is a Geographer who founded a research firm called Three Scale Strategy and a related non-profit called Three Scale Research. The company studies and reports on the economy of the state of Ohio and how Ohio interacts with the rest of the world. His research interests include the study of patterns and changes in population, land use, economics, energy production and transportation.
Data Sources: UN Population Division, International Monetary Fund, Geohive.com
Photo by etrenard, "Niger Portrait"