Population math explained: Growth rate is down, total is up [VIDEO]
Over the past 50 years, the growth rate of the global human population has slowed markedly, from 2.1 percent annual growth in the late ’60s to about 1.2 percent today. Think 1.2 sounds low? Then you need a refresher on exponential growth. If the global population kept growing at that rate, our numbers would double in roughly 60 years (though even demographers’ high-range projections don’t foresee that happening).
So, even while the annual growth rate has been slowing, our overall numbers continue to rise fast –
4 billion in 1974
5 billion in 1987
6 billion in 1999
7 billion in 2011 …
This short video from the Population Reference Bureau does a nice job of explaining how the numbers play out:
For more facts and figures, check out the Population Reference Bureau’s 2011 World Population Data Sheet.
And for more on exponential growth, watch this cult classic video with physics professor emeritus Al Bartlett of the University of Colorado-Boulder, who declares, “The greatest shortcoming of the human race is our inability to understand the exponential function.”