The Sixth Extinction—an Unnatural History
By Elizabeth Kolbert
Henry Holt & Company, New York | 2014
Reviewed by Jane M McCabe
We Have Been Warned
Elizabeth Kolbert is a foremost writer on catastrophic happenings, such as global warming and its consequences (see Field Notes for a Catastrophe, published in 2008.) She is a staff writer for The New Yorker, an observer and commentator on environmentalism. Field Notes attempts to bring attention to the causes and effects of global climate change. To write it Ms. Kolbert traveled around the world where the effects from climate change are the most evident—to Alaska, Greenland, The Netherlands and to Iceland. The effects consists of rising sea levels, thawing permafrost, diminishing ice shelves, changes in migratory patterns and increasing forest fires due to the loss of precipitation.
She writes about America’s reluctance to reduce our carbon emissions, the primary culprit that is causing global warming. And yet, with all the evidence at hand, there are those who deny what is happening to our planet and assign it to “business as usual” on planet earth!
And now with the publication of The Sixth Sense Ms. Kolbert tackles the sister phenomenon caused by carbon emissions—that many species of animals in our world are becoming extinct!
There have been five previous times when our poor planet has undergone widespread extinction:
- 450 million years ago at the end of Ordovician Era
- 370 million years ago in the late Devonian Era
- 250 million years ago at the end of the Permian Era
- The late Triassic Era Extinction, which occurred 200 million years ago
- The extinction at the end of the Cretaceous Era, 66 million years, when the dinosaurs were killed (making way for mammals, humans and our modern world.)
It is believed that this last extinction was caused by a huge asteroid that collided with planet earth on the Yucatan Peninsula, causing such a cloud of dust to blot out the sun and enough heat to broil the planet, wiping out 100% of the dinosaurs, ¾ of all birds, 4/5 of all lizards, 2/3 of all mammals, and 98% of all ocean plankton. Following what is called the KT extinction it took millions of years for life to recovery its former diversity—everything alive today is descended from organisms that somehow survived the impact.
The more we advance in time the more we know about our past. Before the 18th Century Enlightenment we knew little because the tools that we use to investigate our lonely planet careening through space vulnerable to crashing asteroids and poisonous gases, had not yet been developed. Astonishing as it may seem, when President Thomas Jefferson commissioned Lewis and Clark to explore the Louisiana Purchase he expected they would encounter prehistoric creatures. At the end of 18th Century, George Cuvier’s pioneering work in the nascent field of archeology began uncovering skeletons of giants beasts in Europe—mastodons and mammoths.
Until the end of the 18th Century the very category of extinction didn’t exist. Cuvier’s discovery that the earth had undergone extinctions of species, of “a world previous to ours,” was a sensational event, and news of it spread across the Atlantic
Another geologist, Charles Lyell, published in three thick volumes, Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth’s Surface by Reference to Causes Now in Operation. Among the readers who snapped up Principles was Charles Darwin, whose seminal work, On the Origin of Species, remains one of the most influential books ever written.
Our era, since the conclusion of the last ice age 11,700 years ago, is called the Anthropocene Era, the era of human beings. (Keep in mind that Abraham lived approximately 4000 years ago.) We have altered the composition of the atmosphere—the concentration of carbon dioxide in the air has risen 40% in the last two centuries and the concentration of methane has doubled.
Writes Kolbert, “Since the start of the industrial revolution, humans have burned through enough fossil fuels—coal, oil, and natural gas—to add some 365 metric tons of carbon to the atmosphere. Deforestation has contributed another 180 billion tons. Each year, we throw up another nine billion tons or so, an amount that’s been increasing by as much as six percent annually. As a result of all this, the concentration of carbon dioxide in the air today—a little over four hundred parts per million—is higher than at any other point in the last eight hundred thousand years… If current trend continues CO2 concentrations will top five hundred parts per million, roughly double the levels they were in preindustrial days, by 2050. It is expected that such an increase will produce an eventual average global temperature rise of between 3½ and 7 degrees Fahrenheit, and this will, in turn, trigger a variety of world-altering events, including the disappearance of most remaining glaciers, the inundation of low-lying islands and coastal cities [like New York and Los Angeles!] and the melting of the Arctic ice cap. But this is only half the story.
“Ocean covers 70% of the earth’s surface, and everywhere that water and air come into contact there’s an exchange. Gases from the atmosphere get absorbed by the ocean and gases dissolved in the ocean are released into the atmosphere. When the two are in equilibrium, roughly the same quantities are being dissolved as are being released. Change the atmosphere’s composition as we have done, and the exchange becomes lopsided: more carbon dioxide enters the water than comes back out…”
Roughly 1/3 of the CO2 that we have pumped into the air has been absorbed by the oceans. The pH of ocean’s surface water had already dropped .1 making the oceans more acidic than they were in 1800. This increased acidification of the water content has eroded the world’s coral reefs and marked all organisms that build an external shell, such as clams, barnacles and oysters, and following that herring, salmon and whales, as candidates for extinction, and this is but the tip of the iceberg concerning the changes that our lovely oceans will undergo. It reminds me of the verses in the book of Revelation saying that a third of all ocean life will die…
A subsequent chapter deals with the huge number of bats which have been killed because of white fungus called psychrophile. Oddly enough Ms. Kolbert makes no mention of the severe reduction in the number of bees on the planet, nor our inability to ascertain what’s killing them. Bees, as we know, are necessary agents for the pollination of many species of plants.
Here is a bit of news that I find of interest. In a later chapter called “The Madness Gene” we are told that the Neanderthals vanished roughly thirty thousand years ago and that modern human arrived in Europe around 40,000 years ago, leaving a gap of 10,000 years in which humans intermixed with Neanderthals. As a result most people alive today are slightly—up to four percent—Neanderthal!
Ms. Kolbert ends this book on a positive note—just as we have caused the recent chain of events that are precipitating these mass extinctions so we can take measures to curb carbon emissions and to prevent certain animals from becoming extinct. I’m of a less sanguine opinion. I think it’s already too late.