Most Helpful Customer Reviews
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51 of 53 people found the following review helpful:
5.0 out of 5 stars
Deep Science, and Truly Pertinent, February 21, 2001
I 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.
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24 of 27 people found the following review helpful:
5.0 out of 5 stars
Certain Action Must Always Be Based On Uncertain Science, February 23, 2002
One of the most critical aspects of science appears on page 174 of The Two-Mile Time Machine by Richard B. Alley:ALL scientific ideas are subject to revision; we should never be absolutely sure that the truth has been reached. Old ideas should be tested continually, in an effort to tear them down and replace them with better ones. Ideas that survive this constant attack will be especially robust. Experience shows that if we behave as if these surviving ideas are true, we will succeed.... But, on the other hand, the ideas may be true, they may be reasonable approximations of the truth, or we may just be lucky. In science, no idea, be it speculation, hypothesis, theory, law, model, or FACT, is ever considered to be the final answer. That's the way science works. We ALWAYS act on uncertain answers; we never know if something is the truth with a capital T. The Two-Mile Time Machine is not only an excellent exposition of the use of ice core [and other] data to figure out the recent and future climate situation on Earth, but it is an excellent exposition of how science in general works. Richard B. Alley, a participating scientist in the GISP2 ice core project in Greenland, has written an easy-to-read, but pull-no-punches book on a complicated scientific topic. The book starts out with the basics of coring, dating, and analyzing ice, and takes the reader through to the political, social, and ethical implications of future climate changes, and concludes with Alley's take on what our responses should be. He always states how much uncertainty is attached to any of the ideas he writes about. If a person of a non-scientific background is going to have a complaint about the book, it will probably be that the book goes into too much detail about the evidence supporting the ideas. This book is highly recommended to anybody interested in Earth history, climate, Arctic research, the methods of science, and anybody who wants an excellent science read. The book is especially recommended to anybody interested in or involved in the debate over the future of the Earth's climate. All people involved in this issue need to UNDERSTAND the scientific details. The issue of the Earth's climate future has become way too politicized. Our actions are always based on ideas that have some level of uncertainty, but we must act, because the future of humanity will depend on what we do.
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12 of 12 people found the following review helpful:
4.0 out of 5 stars
Not like the cubes in your fridge, February 19, 2004
Alley joins the growing number of field scientists relating their experiences and the they research perform. In his case the field is the top of the Greenland Ice Cap. The research is the study of ice patterns stretching back over 100 000 years. What do these patterns tell us? Need we care? He explains detail with clarity and detail how the research is done, and describes what has been revealed by it. What those finds tells us of the past, present and might mean in the future become the remainder of the book. One thing stands out vividly - climate not only varies more than we believe, it changes far more rapidly than we expected.
The Greenland Ice Cap bears an astonishingly detailed record of environmental events. Far more than simply packed snow, this massive archive keeps information about distant volcanic events, how much salt is in the sea water and what kind of winds played over the Earth's surface. Even conditions in distant Asia are recorded here in the dust layered within the ice. There are records of long periods of cold and announcements about continental drifting. Alley explains all the elements that must be examined in the layered ice, how they came about and why they occurred. Earth's solar orbit, its tilting angle to the sun, and the slow precessional rotation of the poles. All these motions are further complicated by oceanic currents, wind patterns and humidity levels. Alley describes tracking some of the variations as "following a roller-coaster with a man bouncing on a bungee cord while spinning a yo-yo". It's a dizzying picture and he's quick to point out that many points remain unexplained.
Is this an issue that should concern us? Human history from the onset of agriculture has been a period of unusual stability. The future, Alley tells us, is highly uncertain. The only certainty is that climate will change - it must. Global warming is a fact, not a supposition, he asserts. One result of it will be the addition of fresh water into the "conveyor belt" of oceanic water exchange. The North Atlantic is the key site. Interruption of that exchange by extra meltwater from North America will intrude - chilling northern Europe. Human populations will be affected differently in various places. There will be winners and losers in this situation, but the losers will certainly outnumber the winners. How severe will the changes be? "I don't know". How fast will the changes come about? "I don't know". His lack of knowledge doesn't stem from lack of effort. He reminds us that the information gleaned from Greenland is still new. There's much to learn and do. He calls to us: "Send us your brightest students to help, and cheer them on!". A good piece of advice, but not one likely to be taken by a people choosing business instead of science.
[stephen a. haines - Ottawa, Canada]
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