Revisiting Population Growth: The Impact of Ecological Limits

November 28, 2011 • Daily Email Recap

Thanks to Joe Bish for this article.  Originally published by Yale Environment360. See

13 Oct 2011:Analysis

Revisiting Population Growth: The Impact of Ecological Limits

Demographers are predicting that world population will climb to 10 billion later this century. But with the planet heating up and growing numbers of people putting increasing pressure on water and food supplies and on life-sustaining ecosystems, will this projected population boom turn into a bust?

by robert engelman

The hard part about predicting the future, someone once said, is that it hasn’t happened yet. So it’s a bit curious that so few experts question the received demographic wisdom that the Earth will be home to roughly 9 billion people in 2050 and a stable 10 billion at the century’s end. Demographers seem comfortable projecting that life expectancy will keep rising while birth rates drift steadily downward, until human numbers hold steady with 3 billion more people than are alive today.

What’s odd about this demographic forecast is how little it seems to square with environmental ones. There’s little scientific dispute that the world is heading toward a warmer and harsher climate, less dependable water and energy supplies, less intact ecosystems with fewer species, more acidic oceans, and less naturally productive soils. Are we so smart and inventive that not one of these trends will have any impact on the number of human beings the planet sustains? When you put demographic projections side by side with environmental ones, the former actually mock the latter, suggesting that nothing in store for us will be more than an irritant. Human life will be less pleasant, perhaps, but it will never actually be threatened.

Some analysts, ranging from scientists David Pimentel of Cornell University to financial advisor and philanthropist Jeremy Grantham, dare to underline the possibility of a darker alternative future. Defying the optimistic majority, they suggest that humanity long ago overshot a truly sustainable world population, implying that apocalyptic horsemen old and new could cause widespread death as the environment unravels. Most writers on environment and population are loathe to touch such predictions. But we should be asking, at least, whether such possibilities are real enough to temper the usual demographic confidence about future population projections.

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