The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future
Richard Alley, one of the world’s leading climate researchers, tells the fascinating history of global climate changes as revealed by reading the annual rings of ice from cores drilled in Greenland. In the 1990s he and his colleagues made headlines with the discovery that the last ice age came to an abrupt end over a period of only three years. Here Alley offers the first popular account of the wildly fluctuating climate that characterized most of prehistory–long deep freezes alternating briefly with mild conditions–and explains that we humans have experienced an unusually temperate climate. But, he warns, our comfortable environment could come to an end in a matter of years.
The Two-Mile Time Machine begins with the story behind the extensive research in Greenland in the early 1990s, when scientists were beginning to discover ancient ice as an archive of critical information about the climate. Drilling down two miles into the ice, they found atmospheric chemicals and dust that enabled them to construct a record of such phenomena as wind patterns and precipitation over the past 110,000 years. The record suggests that "switches" as well as "dials" control the earth’s climate, affecting, for example, hot ocean currents that today enable roses to grow in Europe farther north than polar bears grow in Canada. Throughout most of history, these currents switched on and off repeatedly (due partly to collapsing ice sheets), throwing much of the world from hot to icy and back again in as little as a few years.
Alley explains the discovery process in terms the general reader can understand, while laying out the issues that require further study: What are the mechanisms that turn these dials and flip these switches? Is the earth due for another drastic change, one that will reconfigure coastlines or send certain regions into severe drought? Will global warming combine with natural variations in Earth’s orbit to flip the North Atlantic switch again? Predicting the long-term climate is one of the greatest challenges facing scientists in the twenty-first century, and Alley tells us what we need to know in order to understand and perhaps overcome climate changes in the future.
From the Inside Flap
"The Two-Mile Time Machine takes a story that has been much discussed in the press and revitalizes it with the author’s infectious enthusiasm and with background information on the history of ice core drilling. It provides an excellent survey for the general reader and those interested in the history of scientific exploration and issues related to science and society." (Thomas J. Crowley, Texas A & M University)
"Richard Alley takes the reader from the rationale for the study of ice sheets to the story of how ice cores are recovered and how we read the climate and environment of the past recorded therein. He does a good job putting his message on the human time scale and makes his information accessible to the general reader." (Lonnie G. Thompson, The Ohio State University) –This text refers to an out of print or unavailable edition of this title.
From the Back Cover
"The Two-Mile Time Machine takes a story that has been much discussed in the press and revitalizes it with the author’s infectious enthusiasm and with background information on the history of ice core drilling. It provides an excellent survey for the general reader and those interested in the history of scientific exploration and issues related to science and society."–Thomas J. Crowley, Texas A & M University
"Richard Alley takes the reader from the rationale for the study of ice sheets to the story of how ice cores are recovered and how we read the climate and environment of the past recorded therein. He does a good job putting his message on the human time scale and makes his information accessible to the general reader."–Lonnie G. Thompson, The Ohio State University
About the Author
Richard B. Alley, Professor of Geosciences at Pennsylvania State University, where he teaches and conducts research on climate change and glacier behavior. A Fellow of the American Geophysical Union, he recently chaired the National Research Council committee that produced the report "Abrupt Climate Changes: Inevitable Surprises." He has won both teaching and research awards for his work, which has included five expeditions to Greenland and three to Antarctica. He has published numerous articles in leading journals such as "Science, Nature," and "Scientific American".
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.
Certain Action Must Always Be Based On Uncertain Science, February 24, 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.
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]