Who Will Protect the Web of Life?/The Intricate Web of Life

An Epidemic of Extinctions

How fast are species being lost? Answers to that question are very inexact. Most of what is being lost is still a mystery to scientists. First they have to establish how many species exist. According to John Harte, ecological scientist at the University of California, Berkeley,  "there are about  one and a half million named species on earth, but we know that may unnamed species  exist, and the total number is probably between 5 and 15 million."  Some raise the estimate to 50 million species or more. Determining the exact number is all but impossible because  "most extinctions  ill occur before the species have even been named and described," according to scientist Anthony C. Janetos.

Modern science has barely begun to decipher the intricate ecological mechanisms that keep natural communities running smoothly.  If humans  do not know how many species there are, how can they understand the complex web of life and how it is affected by extinctions?  How can they tell what the species ' disappearance might mean for the planet's life-support system? 

When scientist try to determine the rate of extinction, their estimates, although varied, are often disheartening.  "Some 50 percent of the world's flora and fauna could be on a path to extinction within a hundred years," states one writer. Harte's prognosis is even more grim:  "Biologists estimate that tropical deforestation will result in the loss of half or more of the existing species on earth during the next 75 years." 

Based on the calculations of scientist Stuart Pimm of the University of Tennessee, National Geographic states that  "11 percent of birds , or 1, 100 species out of the world's 10,000 are on the edge of extinction; it's doubtful that the majority of these 1,100 will live much beyond the end of the [21st century]."  The same magazine stated:  "A team of respected botanists recently reported that one in eight plants is at risk of becoming extinct.  'It is not just species on islands or in rain forests or just birds  or big charismatic  mammals,' says Pimm. 'It's everything and it's everywhere. . .  .It is a worldwide epidemic of extinctions.' "

Next time: The Intricate Web of Life/ Do We Need All These Species? 

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