Six Billion, or Fifteen Billion People?
A Demographic Mount Everest
Michael Tobias (MT): With a global total fertility rate average of 2.4 children per couple, as highlighted in last year’s “2012 World Population Data Sheet” of the Population Reference Bureau a range of assumptions and projections can be ascertained. These figures – known and, as yet, unknown – are likely to impact nearly every aspect of life for humans, as well as most animals and plants across every global biome. In the area of sheer quantifiable numbers of humans what specific trends give you some measure of confidence that global population is stabilizing; what data sounds an alarm and inflicts serious speculative pause?
Leon Kolankiewicz (LK): What gives me some measure of confidence that the global population may be on its way to stabilization is that worldwide Total Fertility Rates have dropped by about half in the last half-century or so. In countries as diverse as Iran and Brazil, populations are now virtually at or even below “replacement level fertility,” that is, about 2.1 live births per female. Moreover, women the world over, when and if provided with educational and economic opportunities, and when given a real choice in their reproductive decisions, tend to choose quality over quantity.
MT: But population growth continues? This is the ineluctable promise of a built-in momentum of couples at their reproductive heights, the somewhat baffling reality of what I have elsewhere termed, “a demographic Mount Everest” in my book, World War III: Population & The Biosphere at the End of the Millennium.
LK: Yes. But while still rapid and unsustainable, it is no longer exponential, because the annual percentage rate of increase is decreasing ever so slowly, having peaked, of course, at about 2% several decades ago. It’s been gradually dropping since.
MT: A rationale for demographic complacency?
LK: Definitely not. The rate of decline is too slow. In 2004, the respected Population Reference Bureau (PRB) estimated the annual growth rate at 1.3%; eight years later, in 2012, PRB estimated the rate at 1.2%, a mere 0.1% decrease.
And because this smaller rate is applied to a larger population base, the annual increment of population increase has not really declined at all. Indeed, PRB has estimated that in 2004 global population grew by about 83 million, while in 2012 it grew by about 84 million.
Moreover, there has been an emerging backlash in the more developed countries among many economists, politicians, pundits and business advocates to the decades-long prevalence of lower birth rates. This manifests itself with cries of alarm over an alleged “birth dearth” or “baby bust,” coupled with at least partially legitimate concern about a growing dependency ratio with the retirement en masse of the baby boomers (and not enough workers from subsequent generations to support them). Of course, since people are living longer, the dependency ratio issue could be dealt with by people having to work a bit longer. But these fears lead to calls for a number of measures to increase fertility by improving the “family friendliness” of society. The record of these measures in achieving their aim tends to be marginal at best, if Europe is any guide. It remains to be seen whether the call of Iranian President Ahmadinejad for Persian women to get back to the bedroom and fulfill their patriotic duty to produce more Iranians will be heeded.
MT: What a notion! So, in sum, taking into account all the positive and negative trends, by the year 2100, what do you see?
LK: Michael, with relatively modest changes in year to year demographic factors (birth and death rates, longevity, etc.) the Earth could well see a global human population ranging from a low of about 6 billion or less to a high of 15 billion or more.
To read the full article, please click here: http://www.forbes.com/sites/michaeltobias/2013/05/03/six-billion-or-fifteen-billion-people-a-discussion-with-environmental-scientist-leon-kolankiewicz-2/