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Showing 1-7 of 7 reviews(5 star). Show all reviews
on January 15, 2012
Of all the books I have read about climate change, "Snowball Earth", by Gabrielle Walker, is definitely one of the best ' and it's not even about the current climate change.

Part of what makes it so good is the style of writing. As the Los Angeles Times said about her later book, An Ocean of Air, 'Walker has a Ph.D. in chemistry, but she writes like a poet.' And, indeed, after an education at Cambridge, Walker has spent most of her career as a science journalist. It's sort of sad that this doesn't happen more often. Usually, those who understand a subject best are not the ones who communicate it. Walker is the exception to this rule.

Take, for example, this passage about the history of life on Earth: "Stretch your arms out wide to encompass all the time on Earth. Let's say that time runs from left to right, so Earth was born at the tip of the middle finger on your left hand. Slime arose just before your left elbow and ruled for the remaining length of your left arm, across to the right, past your right shoulder, your right elbow, on down your forearm, and eventually ceded somewhere around your right wrist. For sheer Earth-gripping longevity, nothing else comes close. The dinosaurs reigned for barely a finger's length. And a judicious swipe of a nail file on the middle finger of your right hand would wipe out the whole of human history."

Another impressive aspect of Walker's writing is her characterization. Wacky, stubborn, and exuberant scientists are brought to life. Instead of just hearing about their work and accomplishments, you feel like you're getting to know them as people. She writes about arguing scientists particularly well. Arguing scientists are so much fun to read about ' that's one reason I loved The Lost World by Arthur Conan Doyle.

However, the best part of this book, by far, is the subject matter. The theory of Snowball Earth is possibly the most awesome thing I have ever heard about. Here's how the story goes:

From what paleontologists can see preserved in fossils, complex life arose at a very specific point in prehistory: the end of the Precambrian. For several billion years before that, the only thing that lived on Earth was unicellular goop. But then, suddenly, all at once, complex organisms burst onto the evolutionary stage.

Something must have caused this dramatic appearance, and a series of scientists from the 1940s on ' most prominently, Paul Hoffman ' likely have discovered what. At the end of the Precambrian, there are signs of ice in rocks all over the world ' scratches, rock deposits, everything that led Agassiz to discover the ice ages.

Because plate tectonics moves everything around so much, though, rocks were not necessarily formed at the location they sit today. Their magnetic field is what discloses their birthplace. Tiny bits of magnetic material, such as iron, line their field up with the Earth's. The Earth's magnetic field is perpendicular to the surface at the poles and parallel to the surface at the Equator. So, if a rock's magnetic field is vertical, it was formed at the poles. If it is horizontal, it was formed at the equator.

Incredibly, scientists found Precambrian rocks, with signs of ice, with horizontal magnetic fields. During that period of prehistory, the equator was covered in ice ' and, therefore, the whole planet, because it's not really possible to freeze the equator without freezing all the other latitudes too.

The scientists determined that, for several instances on the Precambrian, the continents were arranged in a way that was very conducive to ice-albedo feedback. With the smallest trigger, ice from the poles would creep across the temperature zones and meet at the equator. Frozen oceans, frozen land, the whole bit.

And now CO2 comes into the story. Volcanic eruptions naturally release carbon dioxide, but the amount is so small that the oceans have no trouble soaking them up ' unless they're frozen on the surface and cut off from the air. CO2 would gradually build up, in that case, and millions of years later, the greenhouse effect would be so strong that all the ice would melt and the planet would plunge into a state referred to as Hothouse Earth. Then the oceans would start absorbing all the extra CO2, and ice would reappear at the poles, and the cycle would begin again.

Many scientists believe that these Precambrian cycles of extreme heat and extreme cold provided such a strong pressure on organisms that natural selection was pushed to new boundaries. Complex life had an advantage in these extreme conditions, and it flourished. The most catastrophic climatic event our planet has ever experienced, in our knowledge, was what led to the evolution of multicellular organisms, and eventually, us.

It makes me feel very small, the same way that attempting to comprehend the vastness of the universe makes me feel very small. The life we see all around us only exists because of a series of coincidences. Human beings, one of the youngest of the millions of animal species that have ever existed, are alive because of continental drift lining things up in the right way. And who knows what would have happened if things had been slightly different?

Please visit my blog, [...], for more articles about climate change, including many book reviews.
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on November 9, 2003
In this easy-to-read and sometimes entertaining book, Gabrielle Walker tells the story of the discovery of the massive glaciations of pre-Cambrian Earth that have come to be known as "Snowball Earth". The fact that "Snowball Earth" really happened is not controversial, despite what some reviewers have suggested. The basic reason is the well-known fact that the Sun is slowly getting hotter and was significantly less bright a billion years ago. Also not very controversial anymore are other assertions like the fact that the dinosaur extinction was indeed caused by the collision with Earth of one (or more) comets or asteroids. Walker is not uncritical about these facts, just well informed. There are some small misstatements in the book, like the assertion that magnetic pole inversion have happened regularly through geologic time, while, in fact, there was no inversion for an extended period (tens of millions of years) in the Mesozoic. More controversial, is the idea that "Snowball Earth" somehow "caused" the Cambrian animal radiation. This is the subject of just chapter 9. In many ways this is, for me, the most interesting chapter of the book, and also the most problematical. I assume that most of the experts don't doubt a relationship between the end of "Snowball Earth" and the "Big Bang" of animal life. But most would just assume that the big glaciations prevented the radiation of animals, that otherwise were ready to go, with Hox genes and all. Still chapter 9 is very interesting. Many of the discoveries discussed in it, like the finds of trace fossils of known Ediacaran "animals" have not been published in refereed journals. If it were true, Fedonkin's find of slug-like trails left by Kimberellas, would be extremely important. It would prove that this "animal" is indeed an animal, probably related to the common ancestors of mollusks and annelids. It is very strange that the Fedonkin has chosen to use Walker's book to announce such an epochal discovery. I think the explanation is in Gabrielle's picture, in the back of the book: she is so charming and enthusiastic that nobody can avoid bragging to her about their latest finds! My biggest complaint is that this book really needs graphs and pictures.
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on July 30, 2003
Geologists since the eighteenth century have advocated "uniformitarianism," the concept that what is going on to the Earth now is essentially the same as what has gone on before. It is a good rule of thumb, but like most rules of thumb, it requires intelligent neglect or violation, and working geologists do so to form an accurate picture of Earth history. There has sometimes been resistance to violation of the rule; the wipeout of the dinosaurs by an asteroid hit 65 million years ago is now generally accepted, but was not when it was proposed. But even without extraordinary outside forces, our globe used to be a very different place. Between 750 and 590 million years ago, there were sudden lurches in climate that froze even lands at the equator. Or so goes the Snowball Earth Theory. _Snowball Earth: The Story of the Great Global Catastrophe that Spawned Life as We Know It_ (Crown Publishers) by Gabrielle Walker describes the theory and its importance, but the current importance may not be merely its scientific significance. What makes the theory particularly interesting right now is that it is being championed by a colorful Harvard geologist who is attempting to make it accepted geological thought. Walker's surprisingly exciting book is thus not just a summary of ancient geology, but also an entertaining examination of personalities involved.
The snowball Earth theory is not entirely new, but the book is largely the story of Paul Hoffman, a brilliant, driven geologist who was eager to make some sort of difference in his field. Argumentative, energetic, and brilliant, he has a strong reputation as a geologist and as a difficult character. Disputes by him are not objective quibbles published in obscure journals, but stand-up, screaming fights. Partially because Hoffman has taken up a sort of gladiatorial grandstanding for the theory (he has made his own contributions and confirmations), there are equally adamant anti-snowballers. The combative nature of science is on display here; Walker writes, "Science works at its best when somebody puts forward a theory and everyone else tries to pull it down." She is good at describing the pains of field work (something at which Hoffman is adept), but academic battles are the emphasis in her book. Of course Hoffman hopes his ideas share the same fate as those of Alfred Wegener, whose ideas about Plate Tectonics were originally ridiculed; so far, they have survived the challenges about which Walker reports.
Particularly valuable in the theory is the light it might throw on the bloom of life into complex multicellular creatures. Of course a deep freeze would have been disastrous for all the simple slimes that were found all over the Earth when the freeze came. There might have escaped, however, pockets of cells that, according to the theory, were the precursors for the famous Cambrian explosion in the trilobite times. Perhaps the snowball produced the complexity, although this is far from clear. It is one of the many details that is going to have to be argued over. Walker winds up with a description of the Earth's future; if we are still around in a few hundred million years, we might well have to deal with a return of the snowball. It is too hard to think about time lengths of such spans, but geologists routinely do so, although the spans are back in the past. Walker's book is a good introduction to serious thought about such times, and to the very human way such science is done.
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TOP 500 REVIEWERon June 21, 2003
Gabrielle Walker's "Snowball Earth" reads like a gripping detective tale and spellbinding memoir. Her relatively terse epic primarily tells the tale of arrogant, maverick Canadian geologist Paul Hoffman, and how his study of Precambrian geological formations in Namibia, Africa lead inexorably to a new, controversial theory in the geological sciences; "Snowball Earth". Possessed by a zeal equalled only by a religious fanatic, Hoffman, a professor of geology at Harvard University, gradually builds up an impressive theory explaining how the Earth was encased in ice, not once, but probably at least four times, over the course of two hundred million years (He believes it began around eight hundred million years ago.). Furthermore Hoffman has suggested that this was the event which triggered the evolution of metazoan life and the subsequent Cambrian explosion of metazoan phyla. Walker also introduces us to Caltech geologist Joe Kirschvink whose work in magnetostratigraphy supplied important clues that aided Hoffman in shaping his theory. But to her credit, she also spends considerable time discussing important critics such as Columbia University's Nicholas Christie-Blick and University of California, Riverside's Martin Kennedy and noting their substantial objections without sounding dismissive. Told in engaging lyrical prose, Walker's book will interest anyone fascinated with research done by field as well as laboratory geologists. Her book is a splendid little ode to exciting state-of-the-art geology and some of its most fascinating scholars, most notably Hoffman, himself. Without question, this is among the finest popular books on geology that I've come across.
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on May 8, 2004
This book offers a fascinating look at a possible explanation of how life went from single cell organisms to multicellular organisms. Also shows how different scientists can view and interpret the same data in different ways to support their different views. I have a lot of respect for Ms. Walker. Not only does she interview the main scientists that are involved in this debate, she has gone to some pretty remote areas of the world to see the very rocks that these scientists are basing their views on. That is alot more than most people would expect from someone just relating a story.
If you are interested in early life on Earth, you should read this book. If you are interested in how science tries to determine what has gone before, you should read this book. In short, if you are curious about life/science/the earth , "read this book."
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on June 30, 2003
I first heard about the Snowball Earth theory when I saw a documentary about it on the Discovery Channel. I'm usually more of an astronomy fan, but that documentary fascinated me. I picked up this book following that on a chance sighting, and it did NOT disappoint. The book covers the theory, in layman's terms, and the personalities behind the theory, both for and against.
I think that the few poor reviews here are due to a misinterpretation of the book's purpose. Taken as a book meant to actually make a profit by interesting everyday readers, it was excellent. "Science snobs" who feel their points of view under-represented may take offense, but for the rest of us, thank you Miss Walker.
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on May 21, 2003
Clever writing, fascinating scientific controversy. I loved it.
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