The Ends of the World

April 24, 2017
Shedding light on hundreds of millions of years of Earth’s geological history, this dense and revealing volume by science journalist Brannen focuses on mass extinctions. He examines the so-called “big five” mass extinctions, various points over long stretches of time when animal life was “almost entirely wiped out in sudden, planet-wide exterminations.” He gradually works his way from the Ordovician period around 445 million years ago—before even the dinosaurs—toward the late Pleistocene, some 50,000 years ago. Brannen devotes a chapter to each extinction event and makes potentially dull fossil records accessible by talking with current researchers. In Cincinnati, Ohio, Brannen meets the Dry Dredgers, an amateur fossil-collecting group. Southwest Ohio “sits atop bedrock made of an old ocean seafloor,” allowing fossil hunters access and opportunities to study ancient sea life. He also speaks with Stanford University paleontologist Jonathan Payne, who offers insight on the Permian mass extinction 252 million years ago. According to Payne, it was caused primarily by ocean acidification, a problem that exists today when carbon dioxide reacts with seawater. Effectively linking past and present, Brannen winds down with projections for the future and a warning against inaction in the face of climate change. Color photos.

April 15, 2017
A simultaneously enlightening and cautionary tale of the deep history of our planet and the possible future, when conscious life may become extinct."Animal life has been almost entirely wiped out in sudden planet-wide exterminations five times in Earth's history," writes Brannen, who notes later, "life on Earth is resilient, but not infinitely so." An extinction event is defined as "any event in which more than half of the earth's species go extinct in fewer than a million years." The author provides an overview of the five major extinction events that have occurred over the last 300 million years, evidence of which are revealed by the fossil record and appear to be correlated with major geological shifts. The most recent event, the extinction of dinosaurs, provides a case in point. The dominant form of life on Earth for more than 200 million years, they were likely felled by two major catastrophes that occurred around 66 million years ago: "the largest asteroid known to have hit any planet in the solar system...hit Earth...[and] one of the largest volcanic eruptions ever smothered parts of India in lava more than 2 miles deep." Improbably, our planet has survived each of the five major extinctions. Fossils recovered in Ohio give evidence of what appears to have been the first mass extinction, around 450 million years ago, when "a vast tropical sea covered most of present-day North America." Why this occurred is debatable, but it appears to have been associated with a rapid increase in the amount of carbon dioxide in the atmosphere, causing significant global warming. As the author warns, how we prepare for the possibility of a sixth major extinction event may be "existentially, even cosmologically, consequential." Though not as in-depth on the future possibilities as some readers may want, the book is entertaining and informative on the geological record and the researchers who study it. Brannen may not be Elizabeth Kolbert, but he provides a useful addition to the popular literature on climate change.

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Starred review from April 15, 2017

Covering Earth's history since the planet's inception, this volume seeks to understand the past and shed light on the present. Science journalist Brannen (whose work has appeared in the New York Times and the Atlantic) focuses on the Big Five extinctions in Earth's history, so-called because nearly everything that was alive at the time was almost wiped out. These five have garnered intense study lately as the scientific community attempts to figure out how these incidents might inform us about possible future events. While this title is very similar to Elizabeth Kolbert's The Sixth Extinction, Brannen infuses his narrative with tongue-in-cheek humor that does not downplay the seriousness of his subject. In addition, his work is more comprehensive, addressing the controversies that have arisen both in the scientific community and the public sphere but never devolving into unproductive attacks. If readers have time for only one book on the subject, this wonderfully written, well-balanced, and intricately researched (though not too dense) selection is the one to choose. VERDICT Highly recommended for most public libraries.--Laura Hiatt, Fort Collins, CO

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