Not so long ago, the idea of a species winking out of existence was a laughable proposition. Now, it’s accepted science. Not only that, but species are disappearing at a disquietingly rapid rate. In other words, take a good look now at all the animals you can. They may not be around in a few years.
That, at least is the warning of Elizabeth Kolbert’s impactful new book. In her swift and breezy apocalyptic survey, The Sixth Extinction, Kolbert writes about Georges Cuvier, one of the most important scientific researchers whose name is today barely spoken by non-scientists. A temperamental French naturalist who infuriated as much as he enlightened, Cuvier was working at the Paris Museum of Natural History — whose holdings had been liberated by the revolution from Louis XV’s private Cabinet du Roi — in 1795 when he came across some interesting bones that had been shipped to the king decades earlier by one of his explorers in the Ohio River Valley.
Cuvier compared these bones to those of elephants, which they most closely resembled. There were many fascinating discrepancies, particularly with the brick-size teeth. In a 1796 lecture on “the species of elephant, both living and fossil”, Cuvier presented his findings: the American bones came from an animal that no longer existed. He said that the animal he would later term a mastodon had last been alive some five or six thousand years previous.
According to Kolbert, this discovery “of a world previous to ours” — and his followup theory of periodic “cataclysms” — was one of those thunderclap breakthroughs that fundamentally reshapes the way humanity looks at itself and its environment. Cuvier wasn’t an all-around revolutionary thinker, though. He was so set in classical ways of looking at the natural world that he found early theories of natural selection, called transformisme at the time, preposterous. Nevertheless, his discovery that entire species of organisms could be erased entirely from the planet’s surface, and frequently were, was one of science’s first steps towards the realization that humanity could dramatically impact our ecosystem, frequently for the worse.
The first five of the calamitous mass extinction events discussed here — periods of “substantial biodiversity losses” in one chillingly clinical understatement — have all natural suspects. The last of the “Big Five”, after all, took place during the end-Cretaceous period some 65 million years ago, well before hairy bipeds had first waggled their opposable thumbs. That was the mega-disaster caused when a six-mile-wide asteroid smashing into the Yucatan peninsula at about 45,000 miles an hour, with an impact comparable to over one million of the most powerful hydrogen bombs ever tested. An apocalyptic cloud of fiery, toxic debris incinerated much of the Earth’s surface, and sulphurous dust shrouded the sky. “Day turned to night,” Kolbert writes, “and temperatures plunged.”
In this massacre, on land “every animal larger than a cat seems to have died out.” Four-fifths of all lizard and snake species vanished, and the marine ecosystem essentially collapsed for a period of several million years termed by one scientist “the Strangelove ocean.” The 1980 paper first proposing this blockbuster movie-like cause for the period’s well-recorded disappearance of whole swaths of the animal kingdom was initially greeted with some derision. But the fossil record and an easily graspable cause-effect scenario (a comet killed the dinosaurs) quickly made a compelling case. Carl Sagan and other scientists further popularized the idea by proposing that a similar scenario of long-term darkened skies and freezing cold could happen after a nuclear exchange.
Even if humans makes it through without ever lobbing ICBMs at each other, though, our species is already leaving its dark mark on the Earth’s history. In Kolbert’s somewhat haphazardly organized book, she jumps from the scene of one massacre to the next. It’s a globe-trotting environmental crime story. From a field in strip-mall New Jersey to an elegant Italian island castle in the Tyrrhenian Sea, she zooms in on examples of how seemingly small changes portend the great changes to come. Unlike some of the more apocalyptic climate-change writers out there, Kolbert doesn’t use her book to warn that humanity is endangering itself — though it’s impossible to read of these wholesale extinctions and not take the next logical step — so much as to document the full extent of the species’ impact on our surroundings. Many scientists are even starting to call the current era the Anthropocene, in deference to that impact.
In Kolbert’s account, the Anthropocene is marked by accelerated change and disruptions recalling the natural calamities of the past. In other words, humankind is the new asteroid. There’s the ocean acidification and increased carbon dioxide concentrations destroying everything from frogs to coral reefs (increased “biotic attrition” in one of the book’s more memorably clinical terms). “Fragmentation” of ecosystems by residential sprawl, transportation corridors, and ranching and farmland slashes ecosystems to ribbons. Interlocking webs of travel networks make continental boundaries meaningless, mixing flora and fauna together at higher rates of speed, dooming even more. The result, Kolbert writes, is much the same as the pulses of “megafauna” extinctions that started occurring some 40,000 years ago when humans began sweeping across the Earth and wiping out megaherbivores like Cuvier’s North American mammoths. “It might be nice to imagine there once was a time when men lived in harmony with nature,” Kolbert notes dispassionately. But “it’s not clear that he ever really did.”
That rate of human-caused extinction — which is added to the usual, nature-dictated “background extinction rate” of around one mammal species dying out every seven centuries or so — continues today at a murderous rate with no likely end in sight, according to this fairly resigned book. Roughly a quarter of mammal species and perhaps one in ten of all species are currently “headed towards oblivion” in the near future. Kolbert posits that “a century from now, pandas and tigers and rhinos may well persist only in zoos.” She writes in somewhat despondent fashion about ark-like “frozen zoos” where animal samples are kept in deep freeze so that they won’t disappear entirely. “Does it have to be this way?” She asks. “Does the last best hope for the world’s most magnificent creatures really lie in pools of liquid nitrogen?”
There isn’t much in the way of a prescription for change here. Kolbert’s other writings on climate change, particularly Field Notes from a Catastrophe and her frequently incensed New Yorker pieces, have plenty of evidence to show that the hole being dug by climate change is a deep one. There’s an almost blasé cast to her writing that likely comes from having spent so long warning about the obvious and seeing so little demonstrable change.
But there’s realism and then there’s despondency. The Sixth Extinction leans towards the former. Kolbert gamely tries to end her book on a positive note, and it’s a good one. She points out the extraordinary, and mostly volunteer, measures that humanity has taken to save species like the whooping crane and condor from disappearing as examples of what can be done when energies are focused and passions ignited.
Hope does matter in the end, even when it’s slim.
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