Scientific calculations by those who study these things tell us that it took one million years for the world population to reach one Billion.
180 years later it reached 2 BILLION.
45 years later it reached 3 BILLION.
15 years later it reached 4 BILLION.
12 years later it reached 5 BILLION.
By year 2000 it should reach 6.2 BILLION
By year 2070 it should reach 22 BILLION, then double every 15 years thereafter.
They didn't include “Armageddon” factor, if it occurs during this time, but perhaps scientific minds don't put a lot of credence in Biblical prophesy. Nor are we certain they figured in the Y2K factor, either.
However, should their prognosis be correct, there's going to be a lot of folks taking up what we now consider to be crowded space.