A voracious Earth
Some regions - especially in Asia - are overusing their renewable resources.
It's the region of the world that leaves the biggest human footprint. It gobbles up 80 percent of the crop and other plant resources it produces each year. If things don't change, its ecological survival looks iffy.Skip to next paragraph
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Surprisingly, it's not the United States. It's a swath of Asia that sweeps from India to China. And it leads to a startling question: If these areas of the world are nearing an ecological budget deficit, can they sustain their growth much longer?
"Some regions of the world ... consume far beyond 100 percent of what their local ecosystems can provide," says Taylor Ricketts, director of the Conservation Science Program at the World Wildlife Fund in Washington, an author of a recent study on ecological imbalances. "These areas are being subsidized by other ecosystems. They're on a form of life support."
These findings stem from a map built by Dr. Ricketts and his colleagues which shows mankind's ecological footprint for each square mile of Earth's inhabited zones. This geographical representation, published in the journal Nature in June, defies conventional wisdom about consumption, while illustrating the dramatic effect of population density.
The calculation works this way: First, add up all the planet's sun energy converted to organic carbon by plants each year and call it "net primary production" or NPP - about 56 billion tons worth. Now, subtract the portion that human beings use - all the carbon in materials people consume from cotton in clothes to wood in homes to corn flakes and milk in a bowl of cereal.
Ricketts figures that the world's 6.3 billion people appropriate up to a third of the world's NPP a year. While that average sounds sustainable, it disguises key geographical imbalances (and ignores energy use and land-cultivation used in other human-footprint calculations).
For example, most of Siberia effectively uses 0 percent of its local NPP. By contrast, North America uses 23 percent. Surprisingly, that's still less than the worldwide average. North Americans aren't consuming less. They eat up 5.4 tons of carbon per year compared with a modest 1.2 tons for residents of south central Asia. But that part of Asia is far more populous - 1.3 billion people - and more densely packed than North America. As a result, that region consumes enough goods to require 1.6 billion tons of NPP per year or about 80 percent of the carbon output of that area, the study shows.
That's the present picture. If developing nations boost consumption to match industrialized countries, overall human appropriation of NPP would rise 75 percent, Ricketts and his group calculates.
That shift is already happening, argues Norman Myers, a visiting professor of environmental science at Oxford University and coauthor of a new book, "The New Consumers." More than 1 billion people in 20 developing and transitional nations have recently become wealthy enough to begin consuming like Americans. Already, they own one-fifth of the world's automobiles. By 2010, they could own a third. "The road the planet is heading down with all these new consumers will be enormously and gloriously unsustainable," Dr. Myers says in an telephone interview from Oxford, England. "If these consumers want to buy a lot of computers and gadgets - on the whole, that's OK.... But when it comes to cars, the environmental costs are huge."