0465068634 by Martin Rees

Author:Martin Rees [Rees, Martin]
Language: eng
Format: epub
Published: 2012-04-22T00:03:58+00:00

The Sixth Extinction

Geological records reveal five great extinctions. The largest of all happened at the Permian/Triassic transition around 250 million years ago; the second largest, 65 million years ago, wiped out the dinosaurs. But human beings are perpetrating a

"sixth extinction" on the same scale as earlier episodes. Species are now dying out at one hundred or even one thousand times the normal rate. Before Homo sapiens came on the scene, about one species in a million became extinct each year; the rate is now is closer to one species in a thousand. Some species are being killed off directly; but most extinctions are an unintended outcome of human-induced changes in habitat, or of the introduction of nonindigenous species into an ecosystem.

Biodiversity is being eroded. Extinctions are deplorable not just for aesthetic and sentimental reasons, attitudes engendered disproportionately by the so-called charismatic vertebrates— the tiny minority of species that are feathered, furry, or grandly oceanic. Even at the most utilitarian level, we are destroying the genetic variety that may prove of value to us. As Robert May says, "We are burning the books before we've learnt to read them." Most species have not yet even been catalogued. Gregory Benford has proposed a Library of Life project, an urgent effort to gather, freeze, and store a sample of the complete fauna of a tropical rain forest, not as a substitute for conservation measures, but as an "insurance policy."

Threats to the biosphere are becoming ever greater with biotechnical advances. For instance, salmon on fish farms, genetically modified to grow faster and larger, could outcompete natural varieties if they escaped into the wild. Worst of all, new diseases, unwittingly released, could devastate species. Above all, this impending diminution of nature's riche connotes a failure of our stewardship of the planet.

But the yearning for an unspoilt "natural" world is naive. The environment many of us cherish and feel most attuned to—in my case the English countryside—

is an artificial creation, the outcome of centuries of intensive cultivation, enriched by many

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