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82 of 89 people found the following review helpful:
5.0 out of 5 stars
This book is NOT about global warming., August 30, 2005
This review is from: Plows, Plagues, and Petroleum: How Humans Took Control of Climate (Hardcover)
This book is NOT about global warming. At least, not directly about the global warming of the Industrial Age over which extremists from both environmental and industry/government groups loudly wrangle about. Ruddiman's theme is global warming beginning far earlier -- 8000 years earlier. His expertise is in paleoclimatology, study of the climate in long-past eras. He presents a very persuasive case that starting about 8000 years ago, an increased "unnatural" output of carbon dioxide from early human agricultural endeavors began to measurably effect the earth's climate (with the effect intensified a few thousand years later by increased methane emissions from rice farming). It is Ruddiman's conclusion, very clearly presented and well supported with evidence, that this "extra" carbon dioxide has offset the "normal" global cooling that otherwise would have ended the present comfortable "interglacial" period and plunged us once again into an era of heavy glaciation. In short, into yet another Ice Age. Ruddiman's work challenges us to jettison many comfortable myths, among them being that "Mother Earth" is naturally a stable benign guardian and that pre-industrial humans lived in some idyllic, low impact manner. Like "Guns, Germs and Steel", this is a book that has fundamentally changed my perception of the distant past. It is both an important book and a book that makes for fascinating reading. I can scarcely recommend it too much. My advice: Buy it. Read it. Think about it.
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55 of 59 people found the following review helpful:
5.0 out of 5 stars
Exceptional book; well-reasoned; exemplary science; accessible, September 14, 2005
This review is from: Plows, Plagues, and Petroleum: How Humans Took Control of Climate (Hardcover)
Bruce Trinque's review said much of it, but here is more support. Ruddiman's work offers possible hypotheses to explain many puzzling effects. It is clearly written, accessible to non-experts, and of my 3-feet-wide bookshelf on climate issues, if somebody wanted one book, this is what I would recommend. Ruddiman offers two basic hypotheses. The first, as Bruce described, is that humans have been modifying climate for 8000 years via forest-clearing and agriculture. This inhibited the otherwise-natural temperature decline back into an overdue glaciation, as compared with past inter-glacial periods. That's the good news. The bad news, of course, is the current warming that will take us to levels of CO2 and temperature unprecedented for millions of years, and will do so even if we all stopped using oil/gas/coal tomorrow, and he discusses why. The second hypothesis is the most plausible explanation I've seen for some of the puzzling short-term temperature/CO2 gyrations of the last 2000 years. He proposes that major plague pandemics have caused sufficient die-offs, abandoment of farms, and reforestration to temporarily lower CO2 and temperature. This could explain the later-Roman/Dark Ages lower temperatures, followed by the relatively disease-free Medieval Warming Period, in which Greenland was settled, and UK vineyards spread again to current levels, if not quite as far as early Roman. He ascribes the Little Ice Age drop to Bubonic plagues in Europe, and especially, to the death of estimated 50 million native Americans from smallpox and other European diseases. He does enough math to make these claims at least worth further study. He carefully observes that "correlation is not causation" and goes on to calibrate the mechanisms by which pandemic can lead to lower CO2. Ruddiman refreshingly understands the differences between early hypotheses and well-tested theories. He often starts with an observed behavior, then carefully evaluates alternate explanations for it, rather than just offering an answer. This is an exemplary approach to science, and while the hypotheses certainly need testing, this seems like a very productive line of thought that should incite useful further research. Climate analysis always faces the serious problem of extracting trends, and their causes from a very noisy signal. Compared to many competing hypotheses, Ruddiman's seem to be able to explain some gyrations that have often caused people to say "temperatures go up and down randomly anyway." Finally, the book is clearly and calmly written, with careful delineation of facts and conjectures, with plenty of backup. Even more technical details can be found in his earlier articles. Finally, I suspect Edward Tufte would be gladded by many of the charts, which are often simple, but compelling, and far better than words.
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25 of 25 people found the following review helpful:
3.0 out of 5 stars
Interesting, but....., April 9, 2008
Ruddiman presents an interesting hypothesis, but his reasoning leaves out too many factors, and does not give enough weight to unknown factors. Milankovitch cycles are explained extremely well, and Ruddiman attributes ice ages and glaciation periods almost exclusively to these cycles. It is true that ice age/glaciations line up with the Milankovitch cycles, but... we know that further back in planetary history there were Milankovitch cylces that did not result in ice ages. This would indicate that other factors may be required to set off such a radical change in global climate. Ruddiman does not address this, to the detriment of his hypothesis. Ruddiman also states that orbital changes control monsoon cycles, yet research has shown that monsoon cycles can change more rapidly and more often than the long orbital cycles would indicate. Ruddiman also attributes monsoons to heat, stating more heat, more monsoon. This is not an adequate explanation of monsoons. Areas that were very wet 9,000 years ago are undergoing increased desertification today, with increasing heat. Entirely too much is supposed in terms of early human development, the amount of agriculture practiced, and it's effect on climate. As one example, Ruddiman supposes that early nomadic humans spaced children four years apart. There is absolutely no evidence cited for this supposition, and given the high mortality rate and shorter life spans, this type of "spacing" may not have been enough to maintain populations. Too little is known about prehistoric agriculture and population levels to come up with a reliable formula on amount of acres farmed for each person, and amount of methane released per acre. In matching plagues with CO2 levels, Ruddiman does not acknowledge that many climatologists and anthropoligists place cooling weather before the plague events. CO2 levels would have been reduced before as well as durring the plague events. Ruddiman does not give climate enough weight when considering human development and population levels, as well as when considering extincition events at the end of the pleistocene/start of the Holocene. Studies of central american and mesopotanian civilizations have shown that climate changes have had a huge impact on humanity. Climate change has also been linked to the extincions mentioned above. Humanity played a role, but the size of that role is debatable. Ruddiman relies far too heavily on the reasoning that "the only difference was humans, so we must have caused it". This is false logic, as there could have been any number of differences that we can't or haven't picked up on. Given the number of variations possible, it is naive to think we were the only one. The portion of the book that deals with politics is severely lacking. Ruddiman repeatedly takes "alarmists" to task, yet fails to identify the alrmists or the specific claims that are out of line. Same problem with the contrarians. This portion of the book is far too simplistic, and seems to be there only to demonstrate what a reasonable guy Ruddiman is. Lastly, I think Ruddiman goes out of his way to soft-peddle the changes in store. He ignores problems already being seen, such as persistent droughts, in Africa, the U.S. and Australia, to name a few places. Ruddiman also ignores the possibility of rapid climate change. Studies that predate this book have shown that climate can and does change rapidly. Not to be hysterical, but this is something that needs to be considered. Despite what I think are some serious shortcomings, I would recommend this book as Ruddimant is not afraid to put out a hypothesis that is somewhat radical. There are too many unsupported leaps in reasoning, but the overall hypothesis may have some validity, and definitely is interesting.
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