Rates of natural increase (r's) sound deceptively small, but don't be fooled by them! For example, in 2008, r for the lesser developed countries of the world, excluding China, was 0.018. As a percentage, this = 1.8%. Doesn't sound like much, does it? The catch is that there are a bit over 4 billion people in those countries.
G = r * N
G = 0.018 * 4.154 billion ~~ 74.8 million
That is, almost 75 million people were added to those nations in 2008! Remember, this is not simply births, but is the total net gain (births minus deaths).
Is this kind of growth sustainable?
Questions about sustainability are especially important to consider when we remember that not only are numbers increasing, but per capita impact is also increasing. For example, from 1930-1990 the average per capita energy use globally more than doubled. (Per capita energy use is often used as an indicator of environmental impact.)
If exponential growth of cells was taking place within your body, what would it be called? Yes, cancer. Cancer cells are the only kind of cell that grows uncontrollably.
And what is the fate of the cancer cell? Its "joy ride" is cut short by killing its host!
What would happen to a population in nature that experienced this kind of growth? (Say, white tailed deer.) The population size would eventually be controlled by famine, disease or other natural forces. In fact, exponential growth is widely acknowledged to be unsustainable in nature
The question is, can humans get away with unlimited growth or not? Is the growth of the human population fundamentally limited by external (or internal) constraints or not??
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Page maintained by Patricia Muir at Oregon State University; last updated Oct. 21, 2008.