Snowball Earth : The Story of the Great Global Catastrophe That Spawned Life as We Know It

Rating:
Summary: A gripping tale... can't wait to see the ending....
Review: I honestly couldn't put this book down.

I'm a microbial ecologist, and I picked up the book looking for insights into the history of early life on earth. I had read the significant Science and Nature papers on the subject of Snowball earth, but this book was something else entirely. I nearly forgot about my interest in the subject matter and was enthralled by the characters that Walker brought to life.

Snowball Earth is a nice 'story', and I am eager to see how this theory plays out in the coming years. I like it as a working hypothesis for the moment, and I am intrigued by the proposed link between Snowball events and metazoan evolution. The timing seems right, but I don't think a compelling mechanism has really been put forth yet.

Walker does a thourough job on this topic, and I hope she writes more books!

Rating:
Summary: A Biography and Detective Story, Plus a Little Science
Review: I will start with a brief synopsis of the science. In the last six years, many scientists have come to think that an ice age of incredible severity gripped the Earth for a few million years, ending about 590 million years ago. The ocean surface apparently froze all the way to the equator, although the ice may have been thin and patchy near the equator. The Earth's average temperature was about -40 degrees Fahrenheit. Volcanoes belched out greenhouse gases for a few million years, and the atmospheric CO2 levels rose to many times what we have today. The ice receded from the tropics, and the greenhouse effect accelerated, driving the average planetary temperature above 100 degrees Fahrenheit (compared to about 60 today) within a few thousand years or less. This super ice age was the last of 4 to 6 such ice ages, with the first one occurring about 2.4 billion years ago, and the others between 750 and 590 million years ago. These ice ages may have occurred when all of the continents were strung around the equator. (The book presents a theory on why this might be so.) Finally, complex multi-cellular life forms first appeared in the Ediacaran period, shortly after the last super ice age. The book suggests that the last super ice age somehow spurred the appearance of complex life, but does not provide a good explanation of why this might be. (Maybe there is an assumption that "right after X" must mean "because of X.") Finally, the book asserts that such a calamity may occur again about 250 million years in the future.

The book is oddly written: part biography and part detective story, with some science scattered throughout. At no point does the book lay out a comprehensive exposition on the snowball hypothesis. Rather, the scientific theory comes through in bits and pieces as the book goes along. The book is, in large part, a biography of the four men who invented the snowball Earth theory: Paul Hoffman, Brian Harland, Joe Kirschvink, and Dan Schrag. It presents lots of extraneous information about these four guys, especially Hoffman (e.g., his exploits in running marathons). The book hops back and forth between the lives of the fantastic four, all the while letting the scientific mystery play itself out. This is something like a detective story. Many readers will probably like this approach, but I would have preferred that the first chapter explain the "snowball Earth" theory in detail. The rest of the book could then have dealt with how the theory came about, and the people who invented it. Moreover, the book is too narrowly oriented towards geology. Additional emphasis on atmospheric sciences, biology, and astrophysics would have been welcome. (For example, the sun's luminosity has increased about 1% every 200 million years for the last 3 billion years. During the various snowball epochs, the sun's brightness was about 88% to 97% of today's value. At what point is the sun too hot to allow a snowball epoch?)

The book also contains some errors. For example, it states that bacteria survived a trip to the Moon on an Apollo mission in 1967. The first Apollo moon landing was in 1969. Also, the book fails to consider the possibility that complex life may have provided an additional feedback mechanism for regulating CO2 levels in the air. In other words, it may have been that complex life caused an end to the snowball epochs, more so than the snowball epochs stimulating the appearance of complex life.

Finally, the book should, but does not, have pictures, illustrations, and maps.

Rating:
Summary: A Biography and Detective Story, Plus a Little Science
Review: I will start with a brief synopsis of the science. In the last six years, many scientists have come to think that an ice age of incredible severity gripped the Earth for a few million years, ending about 590 million years ago. The ocean surface apparently froze all the way to the equator, although the ice may have been thin and patchy near the equator. The Earth's average temperature was about -40 degrees Fahrenheit. Volcanoes belched out greenhouse gases for a few million years, and the atmospheric CO2 levels rose to many times what we have today. The ice receded from the tropics, and the greenhouse effect accelerated, driving the average planetary temperature above 100 degrees Fahrenheit (compared to about 60 today) within a few thousand years or less. This super ice age was the last of 4 to 6 such ice ages, with the first one occurring about 2.4 billion years ago, and the others between 750 and 590 million years ago. These ice ages may have occurred when all of the continents were strung around the equator. (The book presents a theory on why this might be so.) Finally, complex multi-cellular life forms first appeared in the Ediacaran period, shortly after the last super ice age. The book suggests that the last super ice age somehow spurred the appearance of complex life, but does not provide a good explanation of why this might be. (Maybe there is an assumption that "right after X" must mean "because of X.") Finally, the book asserts that such a calamity may occur again about 250 million years in the future.

The book is oddly written: part biography and part detective story, with some science scattered throughout. At no point does the book lay out a comprehensive exposition on the snowball hypothesis. Rather, the scientific theory comes through in bits and pieces as the book goes along. The book is, in large part, a biography of the four men who invented the snowball Earth theory: Paul Hoffman, Brian Harland, Joe Kirschvink, and Dan Schrag. It presents lots of extraneous information about these four guys, especially Hoffman (e.g., his exploits in running marathons and his early research on other subjects). The book hops back and forth between the lives of the fantastic four, all the while letting the scientific mystery play itself out. This is something like a detective story. Many readers will probably like this approach, but I would have liked the book better had its first chapter explained the "snowball Earth" theory in detail. The rest of the book could then have dealt with how the theory came about, and the people who invented it. Moreover, the book is too heavily oriented towards geology. Additional emphasis on atmospheric sciences, biology, and astrophysics would have been welcome. (For example, the sun's luminosity has increased about 1% every 200 million years for the last 3 billion years. During the various snowball epochs listed in the book, the sun's brightness was about 88% to 97% of today's value. At what point is the solar flux too great to allow a snowball epoch?)

The book also contains some errors and questionable scientific assertions when it ventures outside of geology. For example, it states that bacteria survived a trip to the Moon on an Apollo mission in 1967. It was, I thought, well known that the first Apollo moon landing was in 1969. Also, the book fails to consider the possibility that complex life may have helped prevent further snowball epochs by providing an additional feedback mechanism for regulating CO2 levels in the air. In other words, it may have been that complex life stimulated an end to the snowball epochs, more so than the snowball epochs stimulating the appearance of complex life.

Rating:
Summary: Easy read about scientific facts and speculations.
Review: 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.

Rating:
Summary: Snowfights
Review: It is always exciting to learn about new ideas on the cutting edge of any science. The idea of a Snowball Earth has sparked many debates and arguments. Snowball Earth, by Gabrielle Walker does more than defend the theory in face of academic scrutiny. She manages to introduce the reader to the man behind the theory, and in effect, write a story that resembles, the relationship between the man and his theoretical construct. This is what makes Snowball Earth, such a fascinating work. We are allowed to witness the man at his best, and at his worst. We are given an honest and open-minded view of the individual and his sometimes-sour relationships with others (generally those who do not follow his ideas). His arrogant and egotistical nature is not excused in any way, more fittingly it is used as a reason for his genius. The capacity to strongly trust what he believes in, makes Dr Paul Hoffman such a champion of his Snowball Earth Crusade, and more of the protagonist in the tale, than the theory itself.

The book opens with a chapter that accurately describes the manner in which Dr Hoffman approaches both life and his work. When still a young Postgraduate student with a passion for distance running, and on his very first attempt at the Boston Marathon, managed to come in a very respectable 9th place. His conviction to the cause, and self-will were the fuels which drove him on in the race, and remain to this day the fuels which drive his ambitions to prove to the world that the world has been through periods of massive freezing, the entire globe has been entirely frozen over, including the equatorial regions. This theory has been contested many times since it was first proposed to the Geological community, due to the fact that perhaps the most fundamental principle in Geology - Uniformitarianism, states that everything in the world behaves today as it always has. Processes, which are occurring today, have been occurring throughout Geological time. This means that we have the capacity to interpret past events through direct observation of present day functions. The idea of a Snowball Earth, then flies in the face of uniformitarianism.

Gabrielle Walker accurately describes the manner in which this affects the relationships between Dr Hoffman and his critics and compatriots. His driven belief in his own abilities (as proven by his Boston Marathon performance) often causes him to bash heads with those around him, not winning him many personal friends in support of his outlandish theory.

Critics of the snowball model (such as Nick Christie-Blick, Hoffman's chief adversary) insist that if at any time the entire surface of the earth was frozen over, the amount of insolation absorbed within the atmosphere, would greatly decrease, due to the nature of ice. The reflection of this radiation back into space would mean that ice depths would increase, and the earth would remain locked in a state of ice indefinitely. Dr Hoffman's Snowball Earth theory entails the periodic covering of the entire surface of the earth, under a layer of ice around 20km thick. This ice would then be thawed eventually after around 100 000 years or so due the combined action of volcanoes, and the releasing of gases such as CO2. These gases are released in the atmosphere, and they, along with the surface of the earth, absorb the incoming solar radiation and re-radiate it back down to the earth's surface. The net effect of this, is that enough internal heat is stored within the atmosphere to raise global temperatures, and in doing so, begin the melting process, which relieve the earth of its frozen blanket, to more closely resemble those conditions we know of today. The way, in which Walker describes complicated scientific processes, is simple and easy to follow, which is the mark of a good scientific biography.

Walker is giftedly able to place the reader in the company of Hoffman and his colleagues as they scour parts of the globe looking for evidence for rocks that would prove the earth had indeed frozen over entirely. We are taken from places as diverse as Svalbard Norway, to closer to home, Namibia. The signs and signatures of rocks that had been frozen are searched for. In order for Hoffman to prove the entire surface had indeed frozen, he needed evidence that showed that the rocks at the equator had frozen too. To do this he needed to identify the mark of rocks that had been frozen, then place them at the equator through the study of palaeomagnetism. When newly formed rock solidifies, it holds with it the magnetic signature of the Earth's magnetic field. By knowing the alignment of that field, you can work out the approximate latitude of that rock at formation. The work of Joe Kirschvink, enabled Hoffman to show that there had indeed been equator rock which at some stage had been frozen. The specific time period searched for by Hoffman was between 750-590 million years ago, the time before the Cambrian explosion. The reasons for this are made very clear by Walker, and explain the draw and attraction of the theory to the layman. Before this time, all life that existed on earth was in the form of a primordial sludge of single celled organisms. After the Cambrian explosion, the world entered a period of massive diversification, in which single celled organisms became multicellular life. We saw the birth of shells, and scales, and spines. Teeth and external and internal skeletal structures. The ancestors of life on earth as we know it today. This is why Dr Hoffman is so interested in finding these specifically aged rocks, with these specific palaeomagnetic signatures. Snowball Earth may then prove to be the catalyst that sparked the emergence of complex life on earth. The cooling and rapid warming of the earth may have created an environment stressful enough to cause single cells organisms to huddle together for survival. Creating specific functions for each cell, and uniting them to form a single complex entity.

The way in which Gabrielle Walker approaches the tropic is informed and passionate. Her capacity to convince the reader of the validity of the theory may even rival that of Dr Paul Hoffman himself. Snowball earth is a fascinating read, with massive contemporary appeal in the wake of modern existential reasoning. We may have found the source of complex life, floating in a glass of cool drink.

Rating:
Summary: Science History in the Making
Review: It is fascinating to watch the unfolding of new scientific theories, particularly after having lived through some of them. For example, when I first began studying geology, continental drift was just beginning to be accepted. This book advances some interesting ideas in Earth history that seem to have good evidence for them. It's also well written and entertaining (although, I agree with the other reviewer who called it too "dumbed down").

The book really, really needs illustrations (there are NONE), and it's astonishing that it does not have them, given the opportunities. There are the stunning landscapes of Namibia and Svalbard that could appear. There really should be photos of the Hamelin Pool, of Stromatolite fossils, of the minerals and rock formations, and of the geologist protagonists. I'd recommend fifty color photos, and I might just buy another copy if a new edition is produced that way.

Minor gripe: There's only one place in the world one can have an "intercontinental train" -- and it's not Canada. Proofreader, hello?

All in all, a very worthwhile read.

Rating:
Summary: "Dumbing down" gone to far
Review: Ok, maybe my title is a bit harsh - the book is still a good read, but it gives the reader absolutely no credit for having any intelligence! "Tabloid reading" would also have been suitable.

If you are not particularly looking to expand your technical knowledge of geology, then this book is an enjoyable read, quite swashbuckling in fact. Its an interesting theory and quite probably true. It was eye-opening to me to such dissent within the geological community over this idea, but then, no theory is good if it doesn't stand up to attack and there is enough false information being generated in science in related and unrelated areas. Even the theory of the dinosaurs being wiped out by a meteorite is still under attack and being modified. And to that extent, Walker documents extremely well how this theory (like any scientific theory) has evolved over time, taking into account new facts and theories, and thus gives the reader an powerful and positive insight into the true scientific process.

Walker is verbally very descriptive, using very simple, "laymans english." She focuses extensively on long winded descriptions of the geologists and their work conditions (didn't realise I was in such a glamourous profession!), with key concepts being reduced to a paragraph or two per chapter. Like the previous review, I agree the book could have done with a few diagrams. Geology is a very visual subject, and concepts which Walker would ramble about over several pages could be neatly summed up in one diagram.

However, I did deplore the authors desire to not give the rocks names. This is a book based on geology and geology by definition is about understanding rocks and the stories they tell. Walker provides excellent descriptions of the rocks, such that I can make a fairly confident guess as to what they are, but she never ever, EVER calls them by their name! Would it have been so hard to add 'commonly known as dolomite' to the first time she described her ubiquitous "pink carbonates" (which in itself is inaccurate). Instead, the poor reader has to endure endlessly repetitions of "squashy bags of water" "beautiful rose pink carbonates with yellow and white boulders" "slimeworld" and other simplified horrors. I am sure even the non-geologist out there would in the end get a little tired of the authors over-emphasis on avoiding any word which might be construed as 'scientific.'

For probably a very colourful treatment of a generally dry and little understood subject, I'd recommend this book. But most scientists (and anyone with half a brain) will probably get a little annoyed with the 'warm and fuzzy' way in which it is written. At least there is always the list of references at the back to get the true scientific picture!

Rating:
Summary: Icy personalities clash over Big Chill while frostily-SLAP!!
Review: Sorry, couldn't help it!

This is a fun, fascinating layman's account of the controversial theory of cryptozoic global glaciation, how it may have been the trigger behind the rise of complex life, and the fieldwork and theorizing that led to it. Another book, _Great Feuds in Science_, detailed how great science really gets done, not just with experimentation and evidence collection, but with clashes of personalities and battling reputations. This is in the same vein, as we follow Paul Hoffman and his allies and opponents through a decade of geological work, in pursuit of evidence supporting or disproving the Snowball theory.

Ms. Walker's intimate style is a bit off-putting, if you're used to the more nuts-n-bolts science writing of an Isaac Asimov or Timothy Ferris. And this book really could have used some portraits, diagrams, and other illustrations. Portraits, especially, given the up-close-and-personal rendering of the principals. But it will keep your interest to the end, and give the reader a sense of discovery, as the bits of the puzzle fall into place. The last chapter is a prognostication on the possibility of a future snowball. Chilling...

Rating:
Summary: The theory takes second place behind the people
Review: The book is mostly about the personality and adventures of Hoffman. I was quite disappointed at how light and glossy the treatment of the science backing up the theory was. I'm still looking for a book that covers the theory more than the personalities. I suspect that the publisher realized the problem with this work and that is why the hardcover was called "Snowball Earth : The Story of the Great Global Catastrophe That Spawned Life as We Know It" while the later paperback version is called "Snowball Earth : The Story of a Maverick Scientist and His Theory of the Global Catastrophe That Spawned Life As We Know It". The change is subtitle reflects the primary focus of the book. The people and personalities, not the theory and science.

Rating:
Summary: Snowball Earth, A Review
Review: There is no doubt left to the reader where Gabrielle Walker, author of the new book Snowball Earth: The Story of the Great Global Catastrophe that Spawned Life as We Know It, stands in the scientific debate over the Snowball Earth Theory. The first line in the acknowledgements of the book reads, "For the past two years or so, I have been a Snowball Earth groupie."

Snowball Earth traces the latest theory to send shockwaves through the geological community. Controversial theories in geology are not new (plate tectonics, and the extinction of the dinosaurs are two that come to mind), and a thorough understanding of the different sides in the debate of these new theories is needed to make sure the theory stands the tests of time and scientific scrutiny. The debates over new theories take place in the scientific journals, at scientific conferences, on field trips, and in the press. A good book about a theory presented for the lay-people can help educate the masses on the various points, pro and con, for the new theory. Unfortunately, Gabrielle Walkers book falls short on this ideal.

Snowball Earth is a semi-biography of the men that have postulated the 'Snowball Earth' theory, who have championed it in the scientific community and who have weathered the storm of debates and controversy over the various parts of the theory. The book opens, and mostly follows, the work of Paul Hoffman who put the many pieces of the puzzle together into the theory that became 'Snowball Earth'. Subsequent chapters focus on other players in the Snowball Earth drama. Brian Harland whose work in Svalbard, Norway leads Walker to dub him "the grandfather of the Snowball" and Joe Kirschvink whose skill with magnets and paleomagnetism helped prove the position of the continents in the tropics at the time of the Snowball. All played a role in bringing life to the Snowball Earth theory and Walker holds each high for the reader to esteem and praise.

Opponents of the Snowball Earth theory are given their due, but each is treated like a cameo character in a movie whose sole role is to come and challenge the hero in the white hat and fall away under the truth of the hero's cause. Scientists like Nick Christie-Blick of the Lamont Doherty Earth Observatory at Columbia University and Martin Kennedy of the University of California, Riverside, are each paraded before the reader to give their opposition to the Snowball Earth theory. The data and counter-evidence collected by these and other geologists has sparked the heated debate over the Snowball Earth theory almost from its inception. In the end though, each is somehow shown to actually provide evidence that supports the Snowball Earth theory.

Walker's treatment of the theory and its proponents is not completely biased. Her skilled writing shows the arrogant and egotistical side of Paul Hoffman and the personality conflicts that all too often arise between strong willed people. The reader can feel the passion each of the players feel for their side of the debate. Walker does an excellent job of putting the reader in her shoes so you feel you are walking the hills of Namibia to see Paul Hoffman's field sites, or are scouring the rocks of Australia with Jim Gehling in search for rare Ediacarian fossils. In the end though Walker's skilled writing and easy-to-read style are not enough. Unless you are already a firm believer in the Snowball Earth theory the reader is left feeling incomplete. The time, effort, and attention to detail Walker gives to Hoffman, Kirschvink and the other proponents of the Snowball Earth theory are not given to those who oppose the theory. The alternate models, such as the 'Slushball Earth', are skimmed over, and in general the reader is left with the impression that the Snowball Earth is the only plausible explanation because that's how Walker presents it. In a way the reader feels patronized, that we are not capable of deciding for ourselves the merits of the theory based on the evidence from all sides of the debate.