The Economist this month reports “Demography isn’t destiny, one hopes”.  For the first time, the United Nations has projected population figures as far ahead as 2100.  The
figures predict that Nigeria, which is currently the world’s seventh
most populous country with 158m people, will be the world’s
third-largest nation by 2100 with 730m people.  However, China’s population is predicted to fall by 450m from a peak in 2025, to 941m. 

The Economist further reports:

"The
global total will continue to rise slowly until 2100, when it will
flatten out at 10.1 billion. During the period of fastest growth, in the
late 1980s, the world’s population was rising by over 88m a year. Now
annual growth is down to 75m and by 2050 it will be only 40m...Overall,
the world’s population is increasingly stable. Below the surface,
strains are growing."

The strains referred to seem largely to be caused by un-natural sex selection (presumably caused by abortion):

"China’s
dependency ratio—the number of children and old people as a share of
working-age adults—is rising faster than Europe’s, which will surely
require scrapping the one-child policy. And China and India will be
driven by conflict if the sexual discrepancies the UN projects come to
pass. In 2025 China will have 96m men in their 20s but only 80m women.
India will have 126m men in that age group and just 115m women."

If population increases in one half of the world are being forecast,
in the developed world there a worrying drop which is forecast to
continue and is already causing many problems such as those mentionedbefore on this blog.  

While negative reports of population growth abound, it is useful to remember that Paul Ehrlich in his 1968 The Population Bomb,
asserted that "The battle to feed all of humanity is over. In the
1970's the world will undergo famines—hundreds of millions of people are
going to starve to death in spite of any crash programs embarked upon
now."  Obviously this didn’t happen and we need to be critical of the biases and assumptions which underlie what we read now too.  One also needs to be wary of accepting as gospel a forecast of the world's population 90 years in the future.

Warren Sanderson,
a senior research scholar at the International Institute for Applied
Systems Analysis in Austria, also highlights the uncertainty of long
range population forecasts: 

"The
medium-range U.N. forecast puts the world’s population at 9.9 billion
in 2075. Our comparable forecast has it peaking in that year at around
8.9 billion.
The difference arises because the new U.N. forecasts assume higher
fertility in the second half of the century than we think justified. The
most important point, however, is that future world population is
extremely uncertain. We compute that in 2075 there is an 80 percent
chance that the world’s population would lie between 7.1 and 10.8
billion people."

A commenter
to a blog on the new United Nations projections commented that we need
to stop having so many children for the sake of our children and
grandchildren.  It is a contradiction worth pondering.