Carrying-Capacity of Spaceship Earth
By Shawn Dell Joyce
Estimates of the earth’s carrying-capacity vary according to which population you are measuring, since some populations live more sustainably than others. Some scientists say that not only are we living beyond earth’s capacity, but we are also eating up future generations’ ability to live within the planet’s means. We are literally emptying the earth’s bank account rather than living off the interest as our ancestors did, and leaving a “balance due” for people of the future.
British geographer, Ernst George Ravenstein is credited with first estimating the carrying capacity of the earth at around 6 billion people. Now, at 6.5 billion, at least a billion of our population does not receive enough food energy to carry out a day’s work. Even though Ravenstein was operating on statistics from last century, he hit fairly close to home.
Before Ravenstein, born in 1834, the English clergyman Thomas Robert Malthus argued that human population always increases more rapidly than food supplies and that humans are condemned to breed to the point of misery and starvation. The 200 years since Malthus’ essay was first published have proven him wrong. We can artificially increase food production above birth rates, and even decline in numbers in the presence of plenty.
The World Hunger Program at Brown University estimated that, based on 1992 levels of food production and an equal distribution of food, “the world could sustain 5.5 billion vegetarians, 3.7 billion people who get 15 percent of their calories from animal products [as in much of South America], or 2.8 billion people who derive 25 percent of their calories from animal products [as in the wealthiest countries].”
Clearly we have passed all sustainable estimates and are now entering the “borrowed time” area of the population chart. In order to provide the projected 9 billion people in 2050 with 2,100 calories a day (what food-aid agencies declare the minimum caloric intake) we would have to double our global agricultural production. Humans have already plowed over most of the usable farm land on the planet, and there is a limit to any field’s fertility. Could Malthus have been right after all?
This is not a new chapter in human history. We have faced starvation before, and triumphed. Lester Brown, the noted environmental analyst, has observed: “In the 15th century, Icelanders realized that overgrazing of their grasslands was leading to soil erosion. Farmers then calculated how many sheep the land could sustain and allocated quotas among themselves, thus preserving their grasslands, and a wool industry that thrives today.”
Here are some steps you can take to reduce your ecological footprint:
–Measure that footprint at www.myfootprint.org
–Walk, bike, or share a ride instead of driving or flying.
–Have a home energy audit to determine how much energy your home is using, and
how much you might save by improving its efficiency.
–Adopt energy-saving habits such as using “low tech” clotheslines instead of the dryer.
–Eat local, in season, and organic.
–Eat less meat.
–Have smaller families and support zero population growth.
Shawn Dell Joyce is a nationally syndicated newspaper columnist and director of the Wallkill River School in Montgomery.
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