Can studying why species once went extinct shed light on the potential effects of extinctions today?
Rupert Darwall Feb. 14, 2014 5:58 p.m. ET The Wall Street Journal
'How much do you miss dinosaurs?" Ronald Reagan once asked, commenting tongue-in-cheek on the 1973 Endangered Species Act. Very much, is Elizabeth Kolbert's answer. "The Sixth Extinction" is in part a roll call of species that have gone or are on their way to "dusty death." Ms. Kolbert, a staff writer at the New Yorker, argues that a new wave of extinctions is happening in the modern era because of us—because of what humans are doing and, ultimately, because of who we are.
She notes the rapid fall in numbers of the poisonous golden frog of Panama, succumbing to a fungus against which it has no protection. Some 5,000 insect species—most of which we don't know anything about—are being lost each year, she says. She mourns the loss of bats from a fungus that prevents them from hibernating (although her concern doesn't extend to bats killed by wind farms when the pressure waves from rotating blades cause their lungs to explode). In language of suppressed anguish, she relates how explorers and fishermen wiped out the great auk, a flightless bird once prevalent across the northern rim of the Atlantic: The last pair was strangled on a barren rock off Iceland in 1844 to become stuffed trophies.
At times, this panorama of death and disappearance becomes oppressive for the chronicler. On a field trip to save frogs from the deadly fungus, Ms. Kolbert sleeps fitfully in a "coffin-like hammock." She momentarily panics at the thought of drowning while swimming off the coast of Italy, near Naples, where she is investigating the effects of carbon dioxide on marine life. Still, she keeps a sense of perspective, enjoying a "very tasty cream tart" while discussing the finer points of mastodon teeth in Paris.
Along the way, Ms. Kolbert evokes Rachel Carson's "Silent Spring" (1962) and uses for a chapter heading the title of a decade-earlier Carson book, "The Sea Around Us." Yet in its relationship to scientific ideas and facts, "Silent Spring" might charitably be described as a prose poem decrying, with portentous imagery, the effects of pesticides on nature. It begins with the fable of an "evil spell" that has crept over a fictitious town in the heart of America.
Like Carson, Ms. Kolbert intends to raise an alarm—this time about global warming. When the Earth's atmosphere changes faster than species can adapt, Ms. Kolbert says, many species will disappear—first hundreds, then thousands, finally "perhaps" millions. The scientists she talks to as she goes about her project are inclined to sweeping claims. While the effect is still alarmist, the book is much less rhetorically overwrought than Carson's cri de coeur and provides insights into the ways in which many scientists view the world.
"We're seeing right now that a mass extinction can be caused by human beings," one scientist tells her. She discusses a 2004 article from the journal Nature that the BBC summarized with the headline: "By 2050 Warming to Doom a Million Species." (Since then, Ms. Kolbert notes, some researchers have raised objections to the article's conclusions.) She quotes another scientist saying that "climate change on its own could generate a level of extinction on par with, or exceeding, the slightly 'lesser' extinction events" of the past.
What raises her book far above "Silent Spring," especially for those who share neither author's ecological fervor, is Ms. Kolbert's use of key incidents in the study of natural history to illustrate how accepted scientific knowledge can be radically disrupted. At a time, like our own, of apocalyptic assertions and predictive hubris, it is tonic to be reminded of such paradigm shifts and of the contingent nature of scientific interpretation.
Ms. Kolbert's account of the demise of the great auk, for instance, is put into the context of the debates between Catastrophists and Uniformitarians. Catastrophists, such as Georges Cuvier, the first naturalist to discover a realm of extinct animals, believed that extinction resulted from sudden geological changes in the past—"revolutions on the surface of the earth," Cuvier called them. The most recent lay just beyond recorded history, he said, captured in ancient myths and texts, including the Old Testament. Uniformitarians, by contrast, led by the geologist Charles Lyell, reacted against biblical chronologies and argued for continuous, gradual change persisting into the present.
Strongly influenced by Lyell, Charles Darwin thought that extinctions were a prolonged, almost undetectable process. Ms. Kolbert writes of Darwin's reluctance to accept the role of human agency in recent extinctions. He held to his views even when the extinction of the great auk was announced nine years after the return of the Beagle from its voyages. Darwin argued that gaps in the fossil record, from the long-ago past, indicated a history imperfectly kept, not the sudden extermination of whole families or orders of animals.
In Ms. Kolbert's telling, species turnover as an extended, continuous process remained the dominant paradigm until the 1980s. Then, in an example of settled science being challenged by interlopers, the Nobel physicist Luis Alvarez and his geologist son, Walter, found evidence that, 65 million years ago, a 6-mile-wide asteroid struck the Yucatán Peninsula. The impact, they claimed, led to a catastrophic extinction that wiped out all non-avian dinosaurs as well as a large proportion of other species. At first paleontologists derided the Alvarezes' findings, but they gradually changed their minds as the geological evidence accumulated.
The mass extinction that Ms. Kolbert tries to chronicle is a product of a more recent paradigm, one in which human action, not evolution over vast stretches of time or catastrophic natural events, pushes species over the brink. Human beings since the onset of the Industrial Revolution, Ms. Kolbert argues, have changed the composition of the atmosphere by burning subterranean sources of energy and releasing carbon dioxide. Some plants and animals adjust by moving, but many, she says, "find themselves marooned. Extinction rates soar." Her narrative teeters uneasily between recounting past extinctions and describing speculative ones caused by global warming. So at times the argument takes a dive into the sea, reflecting a recent shift in environmental focus from the atmosphere to the oceans, to search there for the most likely candidates for extinction.
The current crisis is supposedly ocean acidification, a term for a reduction in alkalinity coined more for its public-relations value than its accuracy. A marine biologist known for his extreme views on coral survival tells Ms. Kolbert that Australia's Great Barrier Reef will be reduced to rubble by 2050. Yet an unmentioned 2010 meta-analysis of 372 papers—the most comprehensive analysis of experimental studies of the topic—concluded that marine biota are "more resistant to ocean acidification than suggested by pessimistic predictions identifying ocean acidification as a major threat to marine biodiversity," a distinctly less alarming conclusion than Ms. Kolbert's.
By the end of "The Sixth Extinction," the story has made yet another turn, as Ms. Kolbert loosens her grip on the global-warming paradigm and traces the extinction of fauna in North America and Australia to the arrival of humans and the tendency of Homo sapiens to make rival hominids disappear. She concludes that the sixth extinction began 120,000 years ago, when humans first left Africa. Man was, she says, a killer "pretty much right from the start." Though it might be nice to imagine that man used to live in harmony with nature, "it's not clear that he ever really did."
Ms. Kolbert ends with a personal plea. We should worry less about the fate of humanity and be more aware of the evolutionary potential of other species. The moral is less dire than anything Rachel Carson might have offered, more an exercise in consciousness-raising than a call to action, and Ms. Kolbert's lively account is thought-provoking, whether or not you agree with its premise.
—Mr. Darwall is the author of "The Age of Global Warming: A History."