Review Of Snowball Earth
Copyright © by Dan Schneider, 12/16/05


  I picked up Snowball Earth, by Gabrielle Walker, for 99¢ at a book discounter, simply because I was aware of the scientific theory of that name, and it seemed interesting to read of the particulars of the debate. What I did not expect was that Walker, a cute, perky, blond British lady, would be the first excellent science writer to emerge in the new millennium. The book is an intriguing and breezy romp through not only the theory, which posits that between 750 and 590 million years ago there were one to four total global freezes, but through the lives of the main players for and against it. This technique is accomplished through a narrative that is not heavy-handed and weighed down with scientific language, yet capable of some poesy that transcends the usual of science writing, and harkens back to the best of Loren Eiseley- the master of the scientific essay:

  But this is also a place where you can travel back in time, to see the other side of the evolutionary equation--the simplest, most primitive creatures of all. They come from the very First moments in the history of life, just after the dust from the Earth's creation had settled. And when these first fumblings of life appeared on Earth's surface, their form was exceedingly unprepossessing. Throughout oceans, ponds and pools, countless microscopic creatures huddled together in a primordial sludge. They coated the seafloor, and inched their way up shore with the tide; they clustered around steaming hot springs, and soaked up rays from the faint young sun. Dull green or brown, excreting a gloopy glue that bonded them together into mats, these creatures were little more than bags of soup. Each occupied a single cell. Each had barely mastered the rubrics of how to eat, grow and reproduce. They were like individual cottage industries in a world that had no interest in collaboration or specialization. They were as simple as life gets. 

  The global freezes described in the book were far more complete than the series of Ice Ages that have gripped the planet the last several million years, and it is posited that the first one of them, especially, was the spur to the diversification of life from simple to complex forms known as the Cambrian Explosion, due mainly to the unique stresses such an extreme condition exerts on life. Prior to that, life on earth had never advanced beyond what Walker terms Slimeworld. The theory was first put forth by Brian Harland of Cambridge University in 1964. The term Snowball Earth was coined by Joseph Kirschvink, in 1992. He was a geologist from the California Institute of Technology; but the main proponents of the theory in recent years have been outlaw scientists Paul Hoffman, a Canadian from Harvard, and Daniel Schrag- the two main foci of the book’s narrative. The posit is that when the continents drift together into supercontinents, such as Rodinia, at the end of the Pre-Cambrian Era, the mass drifts toward the equator, and a snowball sets in, because the seas at the pole need just the right conditions to set a runaway icing effect into motion. Another, earlier Snowball Earth also occurred about 2.4 billion years ago. It was only the fact that the earth’s volcanoes belched carbon dioxide into the atmosphere to melt the ice that the earth did not stay permanently frozen. The earth then entered a hothouse period unlike anything seen since the early molten earth formed. Then the ice returned, and then the buildup of carbon dioxide brought another hothouse, and so on. This all continued over tens of millions of years.

  Walker excellently details all sides of the issue, although she admits her pro-Snowball Earth bias in the acknowledgements of the book: ‘For the past two years or so, I have been a Snowball Earth groupie.’ Hoffman is shown as a boor and fanatic, but also impassioned advocate whose hunches seem to have borne fruit. Other scientists are similarly shown in flattering and not so flattering lights, including Hoffman’s nemeses, Nick Christie-Blick, of the Lamont Doherty Earth Observatory at Columbia University, and Martin Kennedy of the University of California, Riverside. Walker’s style is more reminiscent of the gonzo journalism of the 1960s than the staid science reporting of recent vintage, and it does wonders for the tale. Here is a typically non-science journal opinion of a part of Newfounndland, one of the many places walker traveled to while compiling this book: ‘Nobody could love these barren lands, not even their mother. They are dreary and damp, their plants the color of overcooked spinach and rusty nails; when the wind is not buffeting them or rain beating them down, they are shrouded in fog. The pale, thin caribou wander over them like lost souls.’ This draws a reader in and disguises its knowledge (medicine) with the sugar of an easy paperback read. The book starts off in the same breezy manner, with a wonderful section describing how Paul Hoffman’s lack of true marathoning endurance led him to science and not Olympic laurels.

  The weak points in the book are its lack of maps and illustrations. Science works best in transmitting its ideas when visuals are used. No matter how good a writer Walker is, and she’s among the best out there, this is a lapse in judgment that any editor should have remedied. Also, there is too narrow a focus on the geology in question, and not enough on biology nor meteorology. It’s known, as example, that the sun has been increasing in luminosity since its birth. Yet, the book states that in 250 million or so years another Snowball Earth could occur when a supercontinent forms. But, could that happen with a brighter sun? After all, the last supercontinent, Pangaea, of a quarter billion years ago, left no evidence of a Snowball Earth. Hoffman states it did not last long enough, but, even his theory calls for it to take only a few centuries for a runaway process to begin. That’s a blink of an eye, geologically, but well within the time frames needed during Pangaea’s several million year continental get-together. Little things like this, however, will provide the holes that a newer, younger version of Hoffman will need to debunk the Snowball Earth once it becomes dogma.

  One need only look at the success of the Luis Alvarez K-T Impactor theory as the cause of dinosaur extinction to see theory quickly become dogma, then unravel. It was derided, soared to near universal acceptance in the late 1980s, but now is slowly rotting away under the evidence that volcanoes, and possible genetic stagnation were as responsible, if not more so, than the Impactor. Another rather small downside of the book is the denigration of rival theories that explain some of the things that the Snowball earth theory does not, mainly the Slushball Earth theory, even though some of the gaps, to a lay eye, seem big enough to warrant a more balanced presentation.

  Yet, Walker triumphs above it all. This is a first-rate book, and I hope Walker has a long career ahead of her, for science depends on an engaged public, and to achieve such their need to be the explainers, as Walker, who are every bit as good at what they do as the thinkers, like Hoffman and company are. And, given these benighted times, we need a good healthy scientific community more than ever.

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