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.”
More stories in this series:
Yeah, yeah, you know — the world population is hitting 7 billion this year. Here are some facts about the world’s people that you might not already be familiar with.
Here’s a population angle you might not have considered before: Family planning can help women adapt to climate change that’s already happening.
“Science” magazine took the good bits from its recent special issue on population and squished them into this handy video.
Population growth tends to get blamed on other people. But actually the population problem is all about me: white, middle-class, American me.
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