How has the global human population changed from prehistoric times to 1800? From 1800 to the present? What is projected over the next 50 years?

Question

What will be an ideal response?

Answer 1

"From the dawn of human history until the beginning of the 1800s, population increased slowly and variably, with periodic setbacks. It was roughly 1830 before world population reached the 1 billion mark. By 1930, however, just 100 years later, the population had doubled to 2 billion. Barely 30 years later, in 1960, it reached 3 billion, and in only 15 more years, by 1975, it had climbed to 4 billion. Thus, the population doubled in just 45 years, from 1930 to 1975 . Then 12 years later, in 1987, it crossed the 5 billion mark! In 1999, world population passed 6 billion, and it is currently growing at the rate of nearly 77 million people per year."
"On the basis of current trends (which assumes a continued decline in fertility rates), the UN Population Division (UNPD) medium projection predicts that world population will pass the 7 billion mark in 2012, the 8 billion mark in 2024, and the 9 billion mark in 2047, and will reach 9.1 billion in 2050 . At that point, world population will still be increasing by 34 million per year."