Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future by Peter D. Ward

Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us About Our Future Reviews

• 
  Virginia Arthur

  Why does someone who knows the planet is doomed read books about the fact that the planet is doomed? I don't know.
  
  Every day that I am alive and see the pines, oaks, madrones, maples, titmice, wrens, bushtits, phoebes, spiders, moss, clouds, snow-covered Sierra Nevada foothills and mountains, I am aware of how unlikely, improbable, magnificent, splendid, and beautiful it all is and so ephemeral and so temporary and what a bunch of self-centered assholes the human species is. I know that the time is coming when this is going to all go away, be altered so severely, either through climate change or an asteroid, or more likely, Donald Trump, the Grand Moron of America is going to start WWIII. Every day this is all more and more precious to me. To be alive, now. And it's changing already, quickly, mercilessly. It may be gone in my lifetime--snow, and I love snow, skiing, doing anything in the winter light--may go extinct in my lifetime. I have always known this. Under a Green Sky just verified it all for me in a brilliant way. Ward parses out the earth's mass extinctions then extrapolates it on to current conditions on the planet and the prognosis is dim. We are too selfish and asinine a species to do anything about climate change. He all but says this. I cried at the end of the book. It's tragic we are not evolving even a little bit differently than we are. In the end, we were held hostage by our life spans, pretty short, and this drove everything. Our awareness of our deaths has made us the species that doesn't give a shit about a future, just ours.
  
  Its a brilliant and fascinating book. Ward intersperses his field experiences all over the world within the narrative and he doesn't mince words at the end. Basically, sooner or later, we're _ucked and this beautiful planet as it is right now will go down (is going down) right along with us, never to exist again.
• 
  Daniel Martins

  Fantastic book by great paleontologist and mass extinction specialist Peter Ward. He beautifully describes the scientific process responsible for resolving some of the most intriguing of extinctions: The End-Permian, also known as "The Great Dying".
  
  In recent years, a consensus came about that the majority of mass extinctions, the so called "Big Five", were not caused by asteroid or comet impact. They were greenhouse extinctions, due to a rapid increase in atmospheric carbon dioxide and the extreme climatic conditions that followed. The end of the book brings a cautionary tale about our own actions as a civilization. We've just passed the 400 ppm CO2 concentration threshold. By the end of this century, we could reach 600-800 ppm. That will be disastrous not only for humans, but for animals and plants as well.
  
  It happened before and it could happen again. Let us use paleontology as a tool to prevent what nature is telling us is an all too possible dark future.
  
  - Daniel
• 
  Ideath

  So far, the purple tint of the prose is getting in the way of some interesting geological and paleontological sleuthing (and scientific paradigm politicking). It's like someone told this guy he was a *really good writer*, and he took it to mean that tortured sentences and irrelevant references to cultural icons actually add value. (As if i could cast stones - but then, i'm not writing books.)
  
  One of those people who are in an abusive relationship with language, even though (or because) they love it *so much*. You know who i mean.
• 
  Allen

  There's a lot of good science in this book about past extinction events and their relationship to current global warming. It's an easy read, but the author's style is sometimes irritating in the extreme. He loves to construct these tortuous sentences that ramble through several peripheral reflections before getting to the point. I suppose it's intended to show what a broad thinker he is, but it mostly just makes me wish he'd get to the point. Nevertheless, worth reading.
  
  
• 
  Michael Nutter

  What's the worst-case scenario that could happen in the future because of global warming? This book will tell you. Paleontologist, Peter D. Ward, has spent his entire academic career studying the effects of past climates on the earth's many life forms, and, in my opinion, he speaks with great authority when projecting these findings into the future.
  
  Written almost like a detective novel, Ward leads you through the latest scientific discoveries about past climates and the mechanisms that produced them. Some of the conclusions he reaches are truly disturbing and could almost be read as a call to action for those of us aware of this momentous problem to avert the worst ravages of the climate change that is already upon us. The "green sky" referred to in the book's title represents a lifeless planet earth that could result if global warming is left unchecked.
  
  I read this book after reading
  Climate Wars: The Fight for Survival as the World Overheats because the author of that book referred to this one so often to support his own conclusions. Climate Wars lays out several near-future scenarios that could result from unchecked global warming, and Under a Green Sky completes the picture by showing how the present trends of CO2 accumulation, the primary mechanism of climate change, can lead to a nightmarish longer-term future.
• 
  Ruthie

  While packed with information, this book could use editing. If you can read through the run-on sentence fragments and make the mental corrections necessary, you can get a good picture of the climate history of the planet from one of the foremost paleobiologists in the Pacific Northwest.
  
  Ward talks about the big five mass extinctions, and some of the more minor ones, that have occurred over the past 600 millon years. He connects them with changes in ocean currents and oceanic oxygen levels that result from greenhouse gases trapped in the atmosphere. It gives a good explanation of how delicate our ecosystem is and how radically it has shifted over time. If you are interested in learning more about how or why the climate is changing, this is a good resource.
• 
  Lynne Pennington

  Loved this book. Ward lays out past extinctions very understandably and brings things up-to-date with what is most assuredly our current mass extinction. I am not a scientist, so am delighted when I find a science writer that can handle difficult subjects in a way I can understand without assuming I am an idiot. Great book, well-written. Should be required reading in the U.S., not that it would matter to the masses.
• 
  Peter

  loved it. Like a lot of Peter Ward's books
• 
  Blair

  A Book that Goes Downhill Faster than the Climate
  
  This book begins with an investigation by paleontologist Peter Ward of the cause of the major mass extinctions that have afflicted the earth many times in the past. The extinction question has been dominated in recent decades by hypothesis that the end-Cretaceous extinction was caused by a massive meteorite strike. After this was established to be fact, the search was on for the evidence of the impacts that caused all the other mass extinctions. In the first six excellent chapters Ward presents the detective story, in which he plays a part, of how convincing evidence for impact was never found and other hypotheses came to be considered. The pattern to many extinctions that Ward has discovered is best described in his own words:
  

  "First, the world warms over short intervals of time because of a sudden increase in carbon dioxide and methane, caused initially by the formation of vast volcanic provinces called flood basalts. The warmer world affects the ocean circulation systems and disrupts the position of the conveyor currents. Bottom waters begin to have warm, low-oxygen water dumped into them. Warming continues, and the decrease of equator-to-pole temperature differences reduces ocean winds and surface currents to a near standstill. Mixing of oxygenated surface waters with the deeper, and volumetrically increasing, low-oxygen bottom waters decreases, causing ever shallower water to change from oxygenated to anoxic. Finally, the bottom water is at depths where light can penetrate, and the combination of low oxygen and light allows green sulfur bacteria to expand in numbers and fill the low-oxygen shallows. They live amid other bacteria that produce toxic amounts of hydrogen sulfide, and the flux of this gas into the atmosphere is as much as 2,000 times what it is today. The gas rises into the high atmosphere, where it breaks down the ozone layer, and the subsequent increase in ultraviolet radiation from the sun kills much of the photosynthetic green plant phytoplankton. On its way up into the sky, the hydrogen sulfide also kills some plant and animal life, and the combination of high heat and hydrogen sulfide creates a mass extinction on land. These are the greenhouse extinctions."

  Ward identifies three different states of the ocean through time. The well mixed ocean of today, with animal life at all levels, is only present during the geologically short periods when there is permanent ice at the poles. The temperature difference between the equator and the poles is required drive the ocean circulation that oxygenates the deep ocean. In warmer times the temperature difference is less, ocean is more stratified, and the bottom layers are anoxic with little non-bacterial life. Throughout the long pre-Cambrian era the oceans were in a third state called a Canfield ocean, which is dominated by sulfur metabolizing bacteria. Ward's hypothesis is that the Canfield oceans return in response to greenhouse warming and cause mass extinctions. This leads to the question of whether the present greenhouse warming will eventually lead to the same result.
  
  One problem with understanding global warming is that the time scales involved are beyond normal human experience. Climate modelers may talk of a 50 year "sweet spot" where results are not affected much by emissions scenarios, but the implication that any changes we make today will not be felt for half a century is not something mentioned very often at events like Live Earth concerts. At the same time, what we do over the course of the next 50 years will profoundly affect the following century. Another problem is people think of global warming in terms of their local weather. Three degrees of warming means you get the climate a few hundred miles to the south. That may not seem to be a big deal if you live in Washington DC and look at the climate of South Carolina or Georgia. It might be of more concern to live in Oregon and look at Baha California. Still, the major effects of global warming will be on the ice caps and the oceans. Melting ice caps could lead to sea level rises of tens of meters over the timescale of a hundreds of years. Ward is introducing the idea that on a timescale of thousands of years we may be causing the conditions that produced previous mass extinctions, with a dead ocean releasing hydrogen sulfide gas. But he fails to justify how the amount of carbon dioxide humanity could produce in a few centuries could reproduce geological process that occur over much longer time periods.
  
  Chapter six ends with the words "This should thus be the end of the book." Indeed, it should have been. The rest of the book is an attempt, in his words, to bridge the "canyon" that exists between the scientists who study the present climate and paleontologists who have studied the mass extinctions of the more distant past. Unfortunately his lack of expertise in modern climate science clearly shows in the increasingly incoherent last three chapters. Perhaps we were warned of this in the book's introduction, which ends with "Thus this book, words tumbling out powered by rage and sorrow but mostly fear..." That might be fine if it were followed up with the careful editing required for a book about science, but it was not.
  
  Chapter seven gives a reasonable description of the cycle of ice ages we are presently in, and their connection to the set of ocean currents that has a large influence on climate. Chapter eight is when the book starts to fall apart. He uncritically presents the ideas of William Ruddiman that agriculture 8000 years ago raised greenhouse gas levels and prevented an ice age from starting over northern Canada, but fails to mention that many climate scientists do not accept this hypothesis. He also claims that Jared Diamond's two books are about how climate changes civilization, when in fact Diamond pays little attention to climate, saying only that there will be winners and losers. He also shows confusion about future carbon dioxide levels, stating "Even if we stayed at a rise of 80 parts per million over the next century, by the year 3000 the atmosphere would have a carbon dioxide level of 450 parts per million." This is nonsense, as shown by his prediction on the next page of 1000 ppm by the year 2100, itself a plausible but very high end estimate. His lack of understanding about the greenhouse effect is demonstrated by the statement on page 165, "Because the heat budget of the Earth is complicated by the effects of the oceans, land, and especially currents (water and air), there is not a linear relationship between carbon dioxide rise and global temperature." The logarithmic relationship between a greenhouse gas concentration and its radiative effects is determined more by atmospheric physics rather than the convection effects he describes.
  
  Chapter nine begins with a return to the style of the first part of the book, with an investigation into the climate of the warm Eocene period 50 million years ago. But after a few pages, we then get a world tour of the mind altering drugs used by people who live in warm climates, followed by a mish mash of global warming information and misinformation. On page 173 we are told there was "absolutely no ice at the poles" during the Eocene, which is not true but implies a sea level 78 meters higher than today. On page 180 we are told sea level will rise by 60 meters if all the ice caps melt (close), but there was a 25 meter rise in the Eocene (actually closer to 50 meters). On the next page we have a 25 foot increase from melting all ice caps! These are only some of the many errors that occur in the last part of this book. I am sure he would give any of his students a D- if they submitted work as sloppy as this.
  
  At this point one may wonder if anyone reviewed this work before publication. But in the final chapter he identifies the reviewers as climatologist David Battisti and geochemist Eric Steig, both from the University of Washington, as is Ward himself. So were the reviewers careless, or did Ward simply not listen? For example, several times he suggests that shutting down the Atlantic current will cause significant cooling in Europe. This is an old idea that climate scientists no longer believe. In particular, the same David Battisti published a paper "Is the Gulf Stream responsible for Europe’s mild winters?" which shows that, contrary to popular belief, stopping the Gulf Stream would make little difference to European climate.
  
  It is unfortunate this distinguished scientist and author of many excellent groundbreaking scientific books has produced a work so hysterical and full of errors. Perhaps the reason can be found his personal accounts of field investigation that usually make his books such a pleasure to read. In his earlier books he performs many almost heroic feats in the course of his field work. This time a recurring theme is that he is no longer able to perform the physical feats that he used to do in the past. This frustration with his personal life seems to have translated into irrational pessimism about the global future.
  
  I highly recommend reading any of Peter Ward's previous books, but I suggest giving this one a miss. It might be a great source for global warming scare stories, but the science supporting the more extreme scenarios described here is lacking. Emotion got the better of him.
• 
  Rossdavidh

  Subtitle: Global Warming, the Mass Extinctions of the Past and What They Can Tell Us About Our Future. A little over 200 million years ago, there was this Thing, called the P-T event (aka Permian-Triassic Extinction Event). About 54% of all families of species were completely exterminated. This requires every last species in the family to be killed off; many families that did survive still lost most of their diversity; over 80% of all genuses (genera) went extinct. The percentage of species lost is even higher, and even among species that survived, most of the individuals died. It's the only known mass extinction of insect species. It makes the asteroid impact that ended the dinosaurs look moderate by comparison. It was really, really, really bad.
  
  Naturally, Peter Ward thinks he knows why it happened, and he thinks something like it is going to happen again, soon.
  
  Of course, "soon" is in geological time. But Ward is talking decades, or at most a century, not millions of years. The scenario he sees is pretty grim: not just higher temperatures, but (induced by higher ambient CO2 and higher temperatures) a different chemistry in the oceans, eventually resulting in acidic oceans and a toxic (and green) sky. The wonder would not be that so much died, but that anything lived.
  
  It doesn't take a lot, either. Basically, life on earth traps carbon, and as more and more carbon gets locked down, the process can accelerate. Oxygen-based chemistries (which most advanced life on earth relies on) do better, and the older, anoxic single-celled life found deep below the ocean surface is far out of sight. But if something like, say, a series of volcanic eruptions, disrupts that chemistry, it can send the process spiraling the other way, as more and more carbon is released from the biosphere and the rising CO2 levels make it harder for what remains to survive, and when it dies more carbon is released. Ward's central thesis in this book is that this is what has caused most of the mass extinctions in our planet's history.
  
  Whether you believe this or not, the bulk of Ward's book is a thoroughly enjoyable account of the vacillations in the scientific consensus on mass extinctions. The death of the dinosaurs is now pretty clearly correlated with an asteroid impact, but within living memory (and Ward's professional career), this was a pretty controversial statement. Ward's narration of how the scientific community came to grips with this uncomfortable fact (which upended the previous prevailing view of how natural history worked), is a fascinating glimpse into a world of tribal loyalties and personal rivalries, and how the truth is thrashed out in spite of all of that.
  
  Odd factoid: just about the time of the K-T event (when dinosaurs went rapidly extinct), there was a great eruption of volcanoes, as represented by a "flood basalt". Basically, there was a whole lot of lava. It seems an odd coincidence, since similar flood basalt evidence of an upsurge in volcanism is found for the other mass extinctions, including the P-T event that was the biggest of them all. Every non-geologist who looks at the data wonders if an asteroid impact can cause an upsurge in volcanic activity. Apparently, the geologist community is pretty unanimous in saying, "no". So, it's just an odd coincidence, at least for now...but just in the last year (long after this book was written), scientists have begun to revisit this. The deep past is a place where a lot of new stuff is getting found all the time.
  
  Back in the late 20th century, just as scientists had adapted their beliefs to the idea that mass extinctions came from outer space, and started looking for evidence of asteroid impacts at the other four or so mass extinction points in Earth's history, the awkward data gave them another problem. There isn't much evidence for it. There's still some debate on this, but basically the iridium layer that wraps the earth at the time of the dinosaur extinction, just isn't there for any of the other mass extinctions, and neither are the other markers of a ginormous asteroid impact.
  
  To hear Ward tell it, he was one of the relatively early converts to the asteroid impact theory for dinosaur extinction; I have no reason to think otherwise but of course I wouldn't know. If he was, though, it's all the more impressive that he was willing to discard this theory for any of the other extinction events when the data suggested otherwise. Scientists, being human, like grand ideas that explain everything, and a theory which has lots of one-off special cases is anathema to this.
  
  Ward does a good job of building up the tension throughout the book, even though the title tells you where he's headed. Like a fiscal crisis or a run on the bank, he portrays the chemistry change which caused the P-T event as not so much caused by volcanism as triggered by it, setting off a self-reinforcing death spiral (in this case much more literal than for Bear-Stearns). Data from coral reefs, polar ice cores, and fossil records all are compared to try to piece together a picture of heat, acid, sulfur and asphyxiation.
  
  Then, we have the Plea For Action.
  
  It's the failing of every book on climate change I have ever read. The author, approaching the end of their tale, tries to wrench society out of its drive towards the cliff face by the intensity of his exhortations. Like a parent lecturing an adolescent, it often achieves little more than causing the audience to tune out (someone remind me of this analogy in five years). Ward obviously is sincere in his belief that our burning of fossil fuels may do what volcanism did in several prior mass extinctions, and wants us to believe as well. He can't help sounding a bit like a fire-and-brimstone preacher; exciting to the converted zealot, perhaps, but unconvincing to anyone who wasn't already, and annoying besides.
  
  It's a minor blemish at the end of a gripping tale, though, and you can always close the book at that point More intriguing (because less well known already) is the story of how a community can change its mind (if slowly and with great divisiveness) about some of its most core beliefs, and then change again as more data is revealed. I doubt this is the last word on mass extinctions and why they happened (or are happening), but it's a great update, and told with passion and dexterity by a writer who obviously knows his material like the back of his hand.
• 
  Elentarri

  An interesting and informative book in which the author investigates the mystery of what caused the various great extinctions in the past, and how this relates to the current environmental situation today. This scientific mystery story involves everything from squabbling scientist, volcanoes, "evil" bacteria, poisonous gases and asteroids to oceanic convection currents and ice core data.
  
  The book was published in 2007. I'm not certain how outdated and thus accurate the data is in light of any new evidence. However, I found the book to be an interesting and entertaining reading experience, with food for thought and things to look up.
  
  Other, Related Recommended Books:
  The Emerald Planet: How Plants Changed History by David Beerling
  Out of Thin Air: Dinosaurs, Birds, and Earth's Ancient Atmosphere by Peter D. Ward
  Oxygen: The Molecule That Made the World by Nick Lane
• 
  Bevan

  Dr. Ward wrote this splendid book in 2007. Much has changed since then, but much of his research remains important today. At the end of the book he sketches out three possible scenarios for the future of our planet. The first one describes the effects of maintaining the status quo. In 2019 that is looking very dubious. The other two describe temperature increases of between 2 and 10 degrees Celsius, and the likely results of those increases.
  
  Dr. Ward explains the mass extinctions that have happened in the past, what caused each and how they were related to each other, and the similarities to our own time.
  
  What this book and many others point out is how our time is different because of the very rapidity of the increase of carbon dioxide and other gases in the atmosphere.
• 
  Stefan Halikowski

  The book reflects on a career of a paleontologist become astrobiologist and reflects on the search for other impact extinctions than the famous K-T one. The answer is ultimately no -- biomarkers are the new scientific instrument of choice in order to measure past plant metabolisms in the rock.
  Given the book's importance, strange how there is not a single copy of it anywhere in Belgium, a country of 10 million people.
  Some typos, no footnotes (popular science), but nice mix of science and personal autobiography. Some of the diagrams could be fleshed out more fully.
  Keen to find the sequel, who can take the story of this fast-moving science forward from 2008 until 2019?
  Got interested in the author through his TED talks.
• 
  Hugh McGuire

  A great book! Ward gives great rundowns of the mass extinctions which were often the barriers between epochs. Explanation of the KT impact theory was wonderful. Gives great perspective about the importance of climate. Has a few typos, and, I believe, when the author discusses the threat to humanity, he underestimates the ability of human ingenuity to adapt to or even alter a changing climate. But a wonderful book, and very convincing that we need to take drastic action to prevent global warming.
• 
  Megan M

  Really great information, though the book was published in 2007 so some of the information is out of date. In some ways it is a product of its time, but Ward lays out the information in a really clear and informative way. The biggest complaint I have with it is probably that it ends on a defeatist note, instead of a call to action, and that can leave people feeling helpless, rather than driving them to take action.
• 
  Brian

  Selected colorful snippets of a scientist's history reveal a horrible future probability from our distant past. Explains how climate science has progressed.
• 
  Antonio Vena

  Capolavoro di scenari, paradigmi, spiegazioni, immagini e prospettiva.
• 
  Keith Akers

  I liked this book. The theory of mass extinctions could have just been presented at the outset, probably in a paragraph or a chapter, but Ward tells it as a story of the search for truth, so we get both the science angle and the politics of science angle. It's a good book to read if you're interested in global warming, mass extinctions, and how science works.
  
  I found his discussion of the politics and personal interactions surrounding the impact hypothesis for the dinosaurs' extinction intriguing and a bit sad, too. It's odd that the scientists can't all just sit down and discuss the science. Some of them, I suppose, did, and Ward tries to present himself in that role. Ward is certainly in a position to address all of this in an authoritative way. It was interesting that some of the points made by the anti-impact people in the case of the dinosaurs' extinction, even though they turned out to be wrong, were helpful in addressing the problems relating to the other extinctions.
  
  I found some of his descriptions of his trips to sites to study the fossils a bit confusing. His descriptions seemed careful enough, and I picked up most of what it was like "working" the sites, but for some reason it was often hard to picture what exactly the site looked like physically and what he did physically. Perhaps some pictures or photos of the sites might have helped. Also, I'd be interested in knowing what his reaction to the "runaway greenhouse" possibility invoked in James Hansen's more recent book "Storms of my Grandchildren" would be. But his point that climate scientists and scientists investigating the mass extinctions should work together is very well taken.
  
  It's important for us to consider the human side of the science story because "how science works" is an issue for a lot of people, who still don't trust science. If you don't trust science, you'll be reluctant to accept the fact of climate change. Ward's discussion leaves the impression that the discipline of science can overcome some pretty strong personal feelings, and in balance leaves us with a good feeling about science even when individual scientists can sometimes be pretty strange.
  
  
• 
  Bradley Jarvis

  Told from the perspective of one of top paleontologists in the world, "Under a Green Sky" provides a rare inside look at the hard work of science in pursuit of answers to some of the world's most important questions. In particular, the book addresses the causes of Earth's mass extinctions, culminating in a set of new insights suggesting that our civilization's carbon emissions are recreating the conditions that caused several of them. Ward posits that global warming will not only lead to great hardship (due to rising sea levels, increasing temperatures, more severe weather, and the spread of disease), but may trigger a loss of species – including our own – much larger than what we have already caused. I first heard of the book's thesis in an article the author wrote for Scientific American a few years ago; now, with more relevant knowledge, it is much more believable, and scary.
  
  That said, I had some problems with the book. The writer's style was a bit annoying at times, mainly due to poor grammar. I also found myself needing other reference books to keep track of what he was talking about (such as when in time, using a geological timescale, that certain events happened). He also seemed totally unaware of peak oil and its potential for slowing the growth of carbon emissions, though it appeared that others in his profession had the same blind spot.
  
  This book is important enough that I'm willing to overlook its comparatively minor problems and recommend it to anyone with an interest in how science works and what it can tell us about the future.
• 
  James

  A clear and carefully researched examination of the past and the possible future of climate and life on our planet. Conditions on Earth have been far weirder at times than I had realized, and probably will be again in the distant future, i.e. tens or hundreds of thousands of years. In the meantime, it's most likely that the next few decades will be harrowing due to the multiple impacts of global warming, as also explained by Al Gore among others - more and more violent storms like Katrina; rising sea levels destroying any major cities that are on coastlines and forcing up to a quarter of humanity to look for higher ground to live on; food production dropping due to the desertification of farmlands; tropical diseases and their vectors moving into the now-temperate parts of the world;
  heat waves killing great numbers of the poor and elderly. Not a cheerful vision, but one we need to acknowledge.
  
  We can still do a lot to slow it down and reduce the amount of change, and we can prepare by making plans to deal with these crises as best we can before they happen; or we can coast along fat, dumb and happy until we wake up in the middle of it. If I had to bet on which way most of humanity will go, I'd put my money on the latter.
• 
  Chris Boraski

  Interesting exploration of the confluence of climate change and extinction from archeological and climate science study perspectives.
  
  Even though many think that asteroids are the cause of extinction, the current research shows that 12 of the 14 major identified extinction events were connected to climate change events.
  
  "The carbon dioxide makes pretty clear that times of high carbon dioxide - and especially times when carbon dioxide levels rapidly rose - coincided with the mass extinctions. Here is the driver of extinction. Here is the cause of changes in the ancient conveyor belts - short-term warming caused by increases in greenhouse gases. The [volcanic] flood basalts that also correspond with those extinctions is the source of the greenhouse gases."
  
  "Without hope there will be no action. As far as can be seen in the present, we have not yet reached the point of no return, or the tipping point. We as a worldwide society can keep carbon dioxide levels below 450 parts per million. If we do not, we head irrevocably toward an ice-free world, which will lead to a change of the thermohaline [oceanic] conveyer belt currents, will lead to a new greenhouse extinction. The past tells us that this is so."
• 
  Leland Miller

  Wonderful research ,many and varied causes and effect,take your pick. I say all of the planet's in our solar system have become hotter,the sun is going through it's 55K year cycle of extreme solar activity. The heat of the sun IS GOING TO GET HOTTER FOR 100s of years. Let it be known that the moon is rapidly increasing in temp. and their are no factories on any of these Orbs. The sun goes extreme,the by product is dependant solo on the makeup /geological character of each orb in our universe subject to the whims of our beloved solar furnace. Nice try Mr. WARD BUT YOU MISS THE TRUTH.
  
  Our solar furnace is warming all the planet's and orbs in our galaxy. The sun is entering into extreme phase of activity. Their are no factories etc. on other planet's or moons. Space energy of every Ray is intensifying and beginning to boil planet's.
• 
  Kyri Freeman

  I've always liked Peter Ward's work because he can write, and it's interesting stuff.
  
  This one is also terrifying, arguing believably that Earth has been poisonous to our kind of life. And could be again. It reminds me of paleontological/oceanic horror by Caitlin Kiernan or Peter Watts, only they write fiction, and this is not.
  
  The book is not only well-written but reads to me like good science, although I freely confess I don't get all the chemistry involved. Ward cites and summarizes a lot of research done by others as well as himself. And it's not just a political screed -- in fact it really isn't one in structure and tone, although since global warming/greenhouse gases cause the deaths... it makes its point.
• 
  Yael

  That the largest mass extinctions in Earth's long history were caused by global warming. The End-Cretaceous Event, associated with a huge impact even, may be an exception, but even that event might have involved global warming as vegetation died out because of dark skies, then caught fire and burned from lightning strikes afterward, generating vast amounts of CO2. The frightening thing is that such events also entail Canfield oceans, large shallow seas devoid of oxygen, filled with methanogenic and sulfur bacteria that ace out everything else in the vicinity, and liberate huge amounts of methane and sulfur into the atmosphere. Not good.