“The Sixth Extinction – An Unnatural History,” by Elizabeth Kolbert, Picador Press, $16
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It's hard to tell the story of the planet’s oncoming ecological obliteration without being sanctimonious, or causing readers to lapse into utter despair. It can lead them to shrug that if the situation is hopeless anyway, they might as well ignore the whole issue and live as if there is no tomorrow – for indeed, there may not be. It's also tricky to address a diverse public of scientists, nature lovers and normal folks concerned about the survival of humanity. Elizabeth Kolbert overcame these obstacles so well that her new book, “The Sixth Extinction – An Unnatural History,” won the Pulitzer Prize for non-fiction last month.
It is well deserved. Kolbert, a talented journalist with The New Yorker, has written one of the most important books of the 21st century.
Extinction, it turns out is a relatively new concept for humanity. Kolbert reviews the scientific debate in the late 18th century, when the French biologist Georges Cuvier presented evidence for the first time that all manner of species once living on Earth had disappeared.
Extinction is a central consequence of natural evolution. Following the fossil chain, scientists can assess the so-called “background extinction” rate. For instance, amongst the 5,500 different species of mammals wandering the earth, barring unusual events, every seven hundred years one should become extinct as a result of competition or unfriendly environmental changes.
The problem is unusual events that cause mass extinctions. When these take place, the carnage is not gradual but painfully immediate and extensive.
Paleontological research reveals five particularly deadly periods during the planet’s history, the fifth being 60 million years ago, apparently caused by that infamous asteroid that collided with the planet at 50,000 miles per hour, crashing into what is now southern Mexico. The impact lifted up a red-hot cloud of debris and water vapor that fried everything in its wake. Sulfur particles rising from the impact site became airborne, blocking the sun, which led to a sharp drop in temperature and photosynthesis levels. It seems that any organism larger than a cat was simply erased in the climatic cacophony.
According to Kolbert, the sixth extinction, which appears to be taking place even as you read this review, is entirely different. It is humans who are driving millions of species to oblivion.
The age of man
An entire chapter in the book is dedicated to a new initiative by scientists to change the name of the present geological age, from the Holocene – which began at the end of the last ice age, some 11,700 years ago – to the Anthropocene – in other words, the age of man.
The argument holds that there is hardly a corner of the earth that is not influenced by human activity. Humans have transformed half the surface of the planet; most of the primary rivers have been diverted or dammed; fertilizer factories produce more nitrogen than plants fix by nature; over half of the fresh water runoff is utilized by humans. And animals and plants everywhere pay a heavy price for the astonishing success of Homo sapiens.
Kolbert takes the reader with her on various journeys to the front, where species are fighting to survive in the face of human proliferation. We join her in caves across the northeastern U.S. where millions of bats traditionally passed the winters in hibernation.
It generally is unfitting to use the word “Holocaust” when writing in Israel about the natural world. But it is truly difficult to think of another term that describes the astonishing dimensions of the mortality caused by a deadly fungus that unexpectedly appeared in these caves. It attacks the skin on the bats’ faces while they hang upside down deep in sleep. The bat awakes but has no physiological answer to the ravaging of its skin. Entire populations are vanishing. The fungus appears to have been brought over unintentionally from Europe and has fared well in its new American home.
The fungus is an invasive species, a phenomenon Kolbert discusses at length. Humans have effectively created a "new Pangaea,” she argues, referring to the ancient mega-land mass that was ripped apart into the continents that we know today.
As humans travel the globe and ship their merchandise, the continents have functionally been reunited. We have changed their ecological assemblage entirely.
Among the horror stories presented in the book is the well-known case of the brown tree snake that hitchhiked on a liner from Papua New Guinea to the island of Guam. It found no natural enemies and in no time, literally devoured the local bird populations. At the peak of the invasion, the density of snakes reached unimaginable levels of 40 per acre.
Yet the main reason for the free-fall in global biodiversity is not invading snakes, but human domination of lands: the shrinking and fragmentation of habitats. Kolbert choose the Amazon to highlight the implications of creating islands of nature surrounded by cattle ranches and settlements.
People have transformed 50% of the 80 million km2 on the surface of the earth not covered in ice, turning virgin terrain into cultivated fields, shopping centers roads or residential neighborhoods. Most of the other half of remaining open spaces is anything but “wilderness,” showing varying signs of a human footprint.
The steady creep of human society isolates entire animal and plant populations. Without reinforcements from their own species, captured in contracting quarters, for many – extinction is only a matter of time.
Forget acid rain; think acid oceans
Israelis are keenly aware of the extreme ecological manifestations of rapiddevelopment. Perhaps less familiar are recent trends in the acidity of the ocean.
As the concentration of atmospheric carbon dioxide rises, more of the gas is absorbed into the oceans, which have already shown a measurable drop in pH levels (acidity).
The oceans are 30% more acidic today than in 1880. Atmospheric CO2 is expected to double by 2050; the corresponding increase in ocean acidity will constitute a 150% increase since the advent of the industrial revolution.
Kolbert joins Italian scientists near Naples who are monitoring an area where the sea is already highly acidic due to underwater volcano emissions. It turns out that there is a fairly clear acidity threshold for marine organisms. When the pH (acidity) level falls below 7.8, a third of the marine species are wiped out. Such levels are anticipated worldwide by 2100.
She then visits a research station on the Great Barrier Reef in Australia, actually finding a group of visiting Israeli scientists there. Coral reefs are often considered the “rainforests” of the sea from the perspective of biodiversity. She shares a story of an Australian marine biologist who once split open a coral the size of a volley and discovered 103 different species of polychate worms inside. Some estimates reckon that as many as 9 million species of crustaceans live in the Great Reef.
Coral ecosystems, however, are particularly sensitive to chemical changes and there are unmistakable signs of trouble already. When the reef cannot renew itself, the entire system collapses. According to Jack Silverman, one of the Israeli scientists Kolbert meets in Australia: “If you don’t have a building, where are the tenants going to go?”
There’s still wildlife worth fighting for
Israel has 115 mammal species and 2,800 local species of plants, but the threats to Israel’s extraordinary natural history are menacing.
One of countless proposals involves housing construction in Mitspeh Naftoah in Jerusalem. This 160-acre park is also home to 500 plant species (a third of those found in all of Great Britain), 100 bird species and the largest gazelle population in the Judean hills. Activists and the JNF are trying to foil the plan, but the city’s leaders remain uncommitted.
In 2011, the OECD reported that a third of Israel’s invertebrates were threatened by local extinction. Damage to aquatic habitats is particularly egregious. For example, 30 years ago over 9,000 gazelles were prancing around Israel’s open spaces; today the number is only 3,000. Some 34 of the species that have become extinct in Israel used to find a home in the local wetlands. But 97 percent of these lands are gone forever.
Israel needs to build 60,000 housing units a year, it is always easier for developers to leave the confines of the city and build on open spaces. Tragically, the zeal to lower housing prices by a few percent for a few years is liable to destroy critical habitats forever. With a little bit of creativity, Israeli need for housing and nature’s need for habitat need not be incompatible: In order to succeed, Israel’s Nature and Parks Authority needs to be more aggressive; the Jewish National Fund needs to continue expanding its research and management program to make its forests friendlier as a habitat and more effective as an ecological corridor. Israelis (and humanity as a whole) need to learn to slow population growth and curb their consumption.
Meanwhile, people everywhere need to rejoice in the fact that there is still wildlife worth fighting for and something to leave future generations.
The book has no shortage of encouraging stories, from captive breeding efforts to save the critically endangered Sumatran rhinoceros (in a chapter entitled “The Rhino Gets an Ultrasound”) to the banning of DDT. Perhaps the greatest virtue of this book is that, despite the very bad news, it does not induce despondency. One walks away with ample inspiration: We can change direction; the sooner the better; and if not now, when?
Professor Alon Tal is on the faculty of Ben Gurion University’s Institutes for Desert Resarch.