Earlier quoted context omitted.
Earth's population isn't growing exponentially or even linearly, though.
Source? Numbers? I know that a few first-world countries like Japan have negative population growth, but is that the case everywhere? Are the countries that having negative population growth enough to offset those with positive?
From a peak growth rate of 2.2% on a base of 3.2 billion in 1962-1963, the world population growth rate declined to 1.2% on a base of 6.6 billion in 2007. That's about 79 million net new people in 2007.
Wikipedia elsewhere reports that 1989 was the year with the largest absolute increase in population, 87.8 million net new people. So shrughes' report of not-even-linear growth seems true, at least for the last 20 years.