I engage in some modest activism on behalf of the environment and a few other causes and I am sensitive about having my facts straight. I keep coming across the following provocative statement: “Today we added 265,000 babies, lost 7,500 acres of rain forest, added 46,000 acres of desert, lost 71 million tons of topsoil, added 15 million tons of carbon dioxide to the air, lost about 70 species–and we get to do it again tomorrow.” Certain of the numbers given seem plausible; others seem possibly inflated. What’s the straight dope here?
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As a rule, R.T., you want to distrust any statement printed on a T-shirt, which is where you’ll usually find this one. (Principal exception: “I’m with stupid.”) But this stuff isn’t as off-the-wall as most wash-and-wear propaganda–in fact, if you allow for the inherent imprecision of global environmental statistics, many of the numbers correspond reasonably well with current scientific consensus.
Today we added 265,000 babies. Close enough. According to the International Programs Center of the U.S. Census Bureau, world population as of October 2002 was increasing by 209,000 per day–361,000 births offset by 152,000 deaths.
Lost about 70 species. No number can be confidently assigned to daily species loss because we don’t know how many species there are now. Orr sought to acknowledge this in his book by saying that on a typical day 40 to 100 species were eliminated. The T-shirt maker evidently figured that this subtlety would be lost on the average T-shirt reader and split the difference. Even the range given by Orr inadequately conveys what a wild-ass guess we’re talking about here. Harvard scientist Edward O. Wilson, one of the leading authorities on biodiversity, estimates that the number of species is between 10 and 20 million, of which a mere 1.5 to 1.8 million have been described. We have no direct knowledge of how many are becoming extinct; it’s hard enough keeping track of mammalian extinctions, and most species are bugs and microbes. However, since species loss is tied to habitat loss, Wilson’s back-of-the-envelope guess is that, assuming 10 million species in the rain forests, we could be losing 27,000 per year, or roughly 75 a day. Wilson also puts it another way: current species loss due to human intervention is probably 1,000 to 10,000 times greater than what would occur naturally.
