Showing posts with label paleontology. Show all posts
Showing posts with label paleontology. Show all posts

The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future Review

The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future
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The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future ReviewI have lived in a good many places in the world, and I think I have never lived in a place where people didn't voice the witticism, "If you don't like the weather here, stick around twenty minutes and it'll change." We are quite used to rapid changes in weather, and all of us seem fascinated by the way one day is different from another, or at the mistakes the weather forecasters make. Only over the past few decades, however, have scientists been able to get a grip on something else fascinating: climate. Ice in Greenland has been piling up year by year for 100,000 years. This ice carries inside it a record of the climate that produced each yearly layer. In _The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future_ (Princeton University Press), Richard B. Alley, who has done research in Greenland and Antarctica, gives us a view of his narrow and deep studies, and tells us why they are important. It is the first book for the layman to show how climate historians are doing their jobs, drilling five inch cores two miles down, and analyzing the ice in many clever ways.
For most of the 100,000 year record, the climate has had wild jumps, centuries of cold followed by abrupt heating. Humans have lived in an anomalous period of stability. There have been climate changes that influenced human life, like the warm spell that lured the Vikings to Greenland and the cold that drove them out, but these represent one degree shifts shown in the recent ice records. Teensy temperature changes have made what we would consider big climate differences, but when it comes to the wild changes, we ain't seen nothing yet.
Yet. Alley devotes the main part of his book, after showing how scientists draw facts out of buried ice, to discussing what drives global climate change over decades and over eons. He is able to paint a vivid, if brief, picture for those who are not acquainted with his field. His comparisons are felicitous, explaining that the ocean loses carbon dioxide when heated just as a carbonated soft drink would, or showing how a glacier pushes Greenland down into the deep, hot, soft rock below like a person sitting on a waterbed full of syrup. He is in no way a scaremonger, and takes the correct tentative tone because we don't have all the information yet. However, he concentrates on a switching mechanism involving the flow of the Atlantic Gulf Stream; it seems that minor changes in temperature or salinity may jam the "conveyor belt" of the oceans as they transfer heat from the equator to northern latitudes. If it does jam, the results for Europe would be disastrous, and it would affect the rest of the world as well. We know about this switch, and there must be others that we do not know about, and all of them may be vulnerable in our current period of stability to being switched off and making the climate careen again. His moderate advice is that climate change is inevitable, that it will trouble more people than it benefits, and that there are reasons to think that what we are doing to the atmosphere may kick it into instability. If we continue, we may well suffer a crash of a climate change that uses up more of our resources than we have; prudence suggests that we all (especially in developed nations) should be trying to reduce our impact per person. We have used the current centuries of stability for all they are worth; if you don't like the weather now, stick around for twenty years or two hundred, because it is going to be quite different.The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future Overview

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Climate Change in Prehistory: The End of the Reign of Chaos Review

Climate Change in Prehistory: The End of the Reign of Chaos
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Climate Change in Prehistory: The End of the Reign of Chaos ReviewAt first I thought that "Climate Change in Prehistory" was too academic and stuffed with dry facts for the non-specialist reader. I changed my mind by the end.
There are certainly lots of facts and technical jargon, but these are enlivened by occasional gems of dry humour. The author has also struck a good balance with technical jargon.
The book is easy to read, although it is not a "popular" account by any means.
The author handles controversial topics well: such as the date of human occupation of the Amercas and the extinction of megafauna in Australia and the Americas. He presents the relevant research (including the occasional crackpot theory) and indicates where consensus or controversy exist.
Readers who want to dig deeper into specific issues have plenty of references and an excellent bibliography to get them started.
The book covers a surprisingly wide range of topics. For example, the effects of changing diets (meat vs carbohydrates) as humans changed from being hunter-gatherers to farmers is
described. The author seems to come to an implicit conclusion in relation to modern diets, but I won't give the game away by revealing it here.
Ancient history is generally taught as starting with the Egyptians and Mesopotamian civilisations, so most students have never been exposed to descriptions of what came before the
evolution of large, settled societies - probably because little beyond conjecture was known until quite recently.
Books such as "Climate Change in Prehistory" show how much we have learned about climate in pre-history in recent decades - and how much a study of the remote past can illuminate current
climate debates.
I was struck by how well Burroughs integrates information from a remarkably wide range of data into his book - ice cores, linguistics, pollen studies, oceanic sediments, tree rings to name just a few.
Readers new to the subject, or who are looking for a less-technical account, might be better off reading "The Long Summer" (Fagan) and "The Little Ice Age" (Grove). These are both excellent introductions to climate and its effects on humans since the last ice age.
"Climate Change in Prehistory" is an excellent book for readers who want to know the latest thinking about how climate has varied and affected humans since the last ice age.
Climate Change in Prehistory: The End of the Reign of Chaos OverviewHow did humankind deal with the extreme challenges of the last Ice Age? How have the relatively benign post-Ice Age conditions affected the evolution and spread of humanity across the globe? By setting our genetic history in the context of climate change during prehistory, the origin of many features of our modern world are identified and presented in this illuminating book. It reviews the aspects of our physiology and intellectual development that have been influenced by climatic factors, and how features of our lives - diet, language and the domestication of animals - are also the product of the climate in which we evolved. In short: climate change in prehistory has in many ways made us what we are today. Climate Change in Prehistory weaves together studies of the climate with anthropological, archaeological and historical studies, and will fascinate all those interested in the effects of climate on human development and history.

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Earth's Climate: Past and Future Review

Earth's Climate: Past and Future
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Earth's Climate: Past and Future ReviewI read this book twice, and wished I had had something like this available to me a few years ago, when I started venturing out into the unnumbered feedback loops, geochemical vagaries and regional idiosyncracies of Quaternary paleoclimatology, trying to form a general picture of it all. But this text isn't just about the Quaternary, mind you, this is a complete introduction to the main issues in Earth's climatology.
That it's mainly PALEOclimatology is unavoidable, since in my opinion "present climatology" is like a nonsense... Climate is an averaged evaluation of regional or global meteorological parameters through time, and the "present" is always too short for such an evaluation. Insight on climate evolution is only gained looking back in time, and projecting our analyses to an immediate future, so it's a science strictly dependent on timescales and perspectives... What we can tentatively tell about our climatic future is still too uncertain, but what was in the past is still available to inform and inspire us to further research, that's why Ruddiman's work is mainly about understanding what happened in the past...
My cheap philosophy aside, I think the author's aim was to introduce the subject from the basics, at a simplified level, in order to teach what kind of processes and interactions are involved in determining Earth's climate and its variability, without having inexperienced readers bogged down into technicalities of all sorts and all together (the necessary way of scientific articles delving deeper into any one very specific topic!). Hypotheses, problems and events are introduced gradually, with a captivating detective-like style, and the telescopic time-perspective (from longer geotectonic time-scales all the way down to centennial and decadal patterns and phenomena, dutifully lingering upon the Milankovic pacemaker) is just what's needed to have the right feeling brought home to students of how the Earth system evolves..
Details of this and that research threads are omitted to aid understanding of the general picture. Bibliographic references provide other information sources for those interested in more..
My own perplexity is on the second chapter: I doubt that such a quick overview of the workings of atmosphere and oceans is enough for those students that never touched any textbooks of meteorology or oceanography. A chapter twice as long would be more informative, I guess making those processes clearer at the outset of the journey would make several students more confident and help them grasp more of what will follow. I know the book is bulky enough already, but more pages and explanations need to be added to the second chapter for teaching's sake...
I have to disagree with the previous reviewer's negativity.. This is an introductory textbook, if any (paleo)climatologist's views had to be included, an encyclopedia would hardly be enough room for all of them!! The last two chapters, on global warming and future climate variability, are the best example of Ruddiman's balance and caution in explaining hypotheses, alternatives, possible fallacies and biases of sorts. As to the reviewer's question, "Who couldn't get a five-star rating discussing climate change and global warming with such a leitmotif?", I invite him to read my review of W.J.Burroughs' "Climate Change: a Multidisciplinary Approach" on the Amazon.co.uk website...
I really hope to see a second edition of Ruddiman's work in the next years, when times will be ripe for exciting updates and more hypotheses to tell...Earth's Climate: Past and Future OverviewWritten from a multidisciplinary perspective by one of the field's preeminent researcher/instructors, Earth's Climate: Past and Future became a classroom favorite by providing an expert summary of climate change past, present, and future. The text worked equally well as either a nonmajors introduction to Earth system science or climate change, or as an upper-undergraduate-level overview of the processes and techniques in climate science.

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The Dance of Air and Sea: How Oceans, Weather, and Life Link Together Review

The Dance of Air and Sea: How Oceans, Weather, and Life Link Together
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The Dance of Air and Sea: How Oceans, Weather, and Life Link Together ReviewTaylor has a nice reporting style which is fine except when he is dealing with more difficult concepts, e.g. Rossby waves, or unresolved issues where the reader can get lost in the back and forth without a proper synthesis. He does particularly well with ecology, but perhaps I think that because I started with more understanding of the concepts. If Taylor finds something interesting or amusing, he will put it in the book even if it has no real link to anything else; this is fine with me as I always enjoyed the extraneous material.
At the end of this write-up is the best explanation of the Coriolis "force" I could find on the web. I will first try to summarize the most important material on air and water circulation.
In general winds and water redistribute heat toward the poles, with winds driving ocean currents such as the Gulf Stream. Since cold air is denser than warm air, you would expect surface winds in the Northern hemisphere (I will focus on that hemisphere) to blow like the trade winds, from north to south, or northeast to southwest because of the Coriolis force. However, surprisingly, there is a high pressure area 30 degrees north (the horse latitudes), causing winds to blow north from there, or from southWEST to northeast because of the Coriolis force. These are the prevailing westerlies which influence US winters, and account much more than the Gulf stream for the moderate winter temperatures in Europe (not just because of the direction from the south, but because they are flowing over water before arriving in Europe, and in winter water is usually warmer than land).

There is also a tendency for colder water to sink, again because of relative density. This relative density is a major contributor to a worldwide pattern of slow ocean circulation (thermohaline circulation) which also helps redistribute heat toward the poles. In the earth's history, sudden release of fresh water from the north pole due to icebergs melting or huge continental lakes quickly draining, has interfered with the thermohaline due to the lower density of fresh to salty water, thereby having a cooling effect on the northern temperate areas.
Monsoons are created because of the temperature differential between land and sea, the sea being cooler in summer, so winds blow on shore carrying moisture. This air rises due to mountains or other causes, therefore cooling, and releasing precipitation.
CORIOLIS "FORCE". "When an object starts to move north or south and is not firmly connected to the ground (air, artillery fire, etc) then it maintains its initial eastward speed as it moves. An object leaving the equator will retain the eastward speed of other objects at the equator, but if it travels far enough it will no longer be going east at the same speed the ground beneath it is. In reality there is no actual force involved, the ground is simply moving at a different speed than the object is "used to". The result is that an object travelling away from the equator will be heading east faster than the ground and will seem to be forced east by some mysterious force. Objects travelling towards the equator will be going more slowly than the ground beneath them and will seem to be forced west. [look up Coriolis force at wisc.edu where there is also a simple diagram]
The Dance of Air and Sea: How Oceans, Weather, and Life Link Together Overview

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