The trend of destiny: The impossibility of population growth

A decade later, Knibbs published another work forgotten today, his magnum opus: The Shadow of the World’s Future – Or the Earth’s Population Possibilities and the Consequences of the Present Rate of Increase of the Earth’s Inhabitants.

“Founded upon a survey of its areas, of the distribution of its present inhabitants, and of their productions, it shows that the menace of the present rate of growth of those inhabitants is most serious,” he wrote in the preface. “This rate is of the order of about one percent per annum. Starting in 1928 with a total of say 1,950 millions of human beings, the existence of such a rate is of the gravest significance, for, in the course of the present century, mankind will be involved in very great difficulties, for which unquestionably it is quite unprepared.”

He made crude estimates of the planet’s “population-carrying power” under four scenarios, based on population densities in various countries at the time and other variables. “The numbers of human beings which the world-surface can carry,” he concluded, “is limited to a relatively small multiple of the existing population.”

Assuming the estimated annual Western world growth rate of 1.16 percent prevailed over the globe, his hypothetical maximum populations of 5,200 million, 7,020 million, 9,000 million and 11,000 million would be reached, respectively, in 85 years (2013), 111.1 years (2039), 132.6 years (2061) and 150 years (2078).   

On Asia: “If, as appears to be beginning already, the multitudes of the East should westernise their conceptions as to what constitutes a reasonable standard of living, the population-problem is at once raised to a plane of greater difficulty. On the other hand, if western races ever abandon their present love of what may seem to some inordinate luxury, and all useless complication of the paraphernalia of social life, it is certain that the population difficulty, for a time at least, will diminish.”

Yet there was “no adequate world-reaction” to the population problem. Knibbs urged a radical change of perspective, of consciousness. What was required was “the attention of every country that can influence the issue.”

How many billion more? Last July, the U.K. Royal Society made a surprise announcement. It launched a major study into a “hugely controversial area” - anthropogenic population growth - to determine how demographic trends might affect development this century.

The announcement was made on World Population Day, July 11^th, 2010. This annual event began in 1989, when the U.N. decided to commemorate the world’s first Five Billion Day, reached in 1987. Almost two and a half decades later, the population had surged by 39 per cent to seven billion this year.

Nevertheless,the agency’s policy focus shifted away from concern over global growth rates to other issues - especially climate change. In its latest report, State of World Population 2011, released this week, the U.N. continues to insist we should no longer be asking "are we too many", but concentrate instead on making the world “better”.

Yet we are now adding the largest numbers in our history. Despite a decline in the global growth rate to about an annual 1.2 percent, demographic momentum is producing an additional 83 million people each year, mostly in the developing world.

By 2025, the world population is projected to reach eight billion. Previous estimates that it would peak around nine billion between 2045 and 2050 now seem unlikely. New U.N. projections suggest it could be as high as 10.6 billion by mid-century. The actual outcome depends on several key variables; with total fertility rates per woman (TFRs) over the next four decades especially critical.

The UN Population Division produced six projections in April this year for the 44^th session of U.N. Commission on Population and Development. In its “medium” scenario, world population would peak at 9.4 billion in 2070 and then start to decline, but only if fertility declines significantly in most developing countries. The high scenario, where fertility remains mostly between 2.2 and 2.3 children per woman, would lead to a world population of nearly 15 billion in 2100, 20 billion in 2200 and 30 billion in 2300.

Hania Zlotnik, the Division’s Director, recently warned that “high-fertility countries may not reduce their fertility fast enough. Even countries with intermediate fertility need to reduce it to replacement level or below to avert continuous population increases to unsustainable levels.”

Ominously, the Population Reference Bureau’s global TFR seems stuck at 2.5 (Africa 4.7), significantly higher than the desired replacement rate of 2.1. Half a TFR unit is the difference between the U.N.'s medium and high projections, and represents about 5 billion extra people by 2100. Can the global population be stabilised humanely before the end of the century, or will it be reduced by Malthusian checks of famine and conflict?

How too, and why, was this cause celebre of the 1960s and 1970s – anthropogenic population growth - displaced by “dangerous” anthropogenic climate change as the “greatest moral challenge of our time”?  That, as they say, is another story.