Catalogue


The two-mile time machine : ice cores, abrupt climate change, and our future /
Richard B. Alley.
imprint
Princeton, N.J. : Princeton University Press, c2000.
description
viii, 229 p. : ill., map ; 24 cm.
ISBN
0691004935 (alk. paper)
format(s)
Book
Holdings
More Details
imprint
Princeton, N.J. : Princeton University Press, c2000.
isbn
0691004935 (alk. paper)
catalogue key
4030205
 
Includes bibliographical references and index.
A Look Inside
About the Author
Author Affiliation
Richard B. Alley is Professor of Geosciences at The Pennsylvania State University.
Excerpts
Flap Copy
" The Two-Mile Time Machine takes a story that has been much discussed in the press and revitalizes it with the authors 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
First Chapter

FAST FORWARD

We live with familiar weather-ski areas are snowy, deserts are parched, rain forests drip. But what if our climate jumped to something totally unexpected? What if you went to bed in slushy Chicago, but woke up with Atlanta's mild weather? Or worse, what if your weather jumped back and forth between that of Chicago and Atlanta: a few years cold, a few years hot? Such crazy climates would not doom humanity, but they could pose the most momentous physical challenge we have ever faced, with widespread crop failures and social disruption.

Large, rapid, and widespread climate changes were common on Earth for most of the time for which we have good records, but were absent during the few critical millennia when humans developed agriculture and industry. While our ancestors were spearing woolly mammoths and painting cave walls, the climate was wobbling wildly. A few centuries of warm, wet, calm climate alternated with a few centuries of cold, dry, windy weather. The climate jumped between cold and warm not over centuries, but in as little as a single year. Often, conditions "flickered" back and forth between cold and warm for a few decades before settling down.

The history of this climatic craziness is written in cave formations, ocean and lake sediments, and other places. But the record is probably clearest and most convincing in the ice of Greenland. This incomparable, 110,000-year archive provides year-by-year records of how cold and snowy Greenland was, how strong the storms were that blew dust from Asia and salt from the ocean, and even how extensive the wetlands of the world were.

These records show clearly that Earth's climate normally involves larger, faster, more widespread climate changes than any experienced by industrial or agricultural humans. The 110,000 years of history in Greenland ice cores tell of a 90,000-year slide from a warm time much like ours into the cold, dry, windy conditions of a global ice age, a 10,000-year climb back to warmth, and the 10,000 years of the modern warm period. But the ice cores also show that the ice age came and went in a drunken stagger, punctuated by dozens of abrupt warmings and coolings. The best known of the abrupt climate changes, the Younger Dryas event, nearly returned Earth to ice-age conditions after the cold seemed to be in full retreat. The Younger Dryas ended about 11,500 years ago, when Greenland warmed about 15°F in a decade or less. A little more, slower warming then led to our current 10,000 years of climate stability, agriculture, and industry.

But smaller and slower climate changes during recent millennia have affected human civilizations in many ways-and these small climate changes seem to have been getting bigger. The "Little Ice Age" cooling that changed settlement patterns in Europe a few centuries ago was tiny compared to the Younger Dryas or the global ice age, but seems to have been the biggest change for thousands of years.

Records from many places beyond Greenland provide a longer, if fuzzier, view of climate history. Over the last million years, the pattern recorded in cores of Greenland ice has occurred over and over: a long stagger into an ice age, a faster stagger out of the ice age, a few millennia of stability, repeat. The current stable interval is among the longest in the record. Nature is thus likely to end our friendly climate, perhaps quite soon; the Little Ice Age may have been the first unsteady step down that path.

In our climate, great ocean currents sweep north along the surface of the Atlantic, are warmed by the tropical sun, and release that heat into the winters of northern Europe, allowing Europeans to grow roses farther north than Canadians meet polar bears. The ocean waters that cool in the north Atlantic then sink into the deep ocean and flow south on the first stage of a globe-girdling journey before returning. This "conveyor belt" circulation is delicately balanced-add a little too much fresh water to the north Atlantic from rain or melting icebergs, and the wintertime ocean surface will freeze to produce floating sea ice rather than sinking to make room for more hot water. Much evidence shows that the abrupt coolings and warmings occurred when the conveyor circulation suddenly shut off or turned on again, triggering other changes that spread across Earth.

Human-induced greenhouse warming appears capable of triggering a conveyor shutdown, by increasing precipitation in the far north and by melting some of the remaining ice sheet on Greenland. Strange as it seems, "global warming" may actually freeze some regions! But, if we slow down the warming, it is just possible that we can avoid an abrupt change and even help stabilize the climate.

This book is a progress report on abrupt climate changes. We will discuss what has been learned, how this knowledge was gained, and what it might mean to us. The existence of abrupt climate changes casts a very different light on the debate about global warming, so we will examine the greenhouse arguments under this new light. We won't find all of the answers-many are not known yet-but we will frame the questions, and we may gain some clues to our future.

Climate Matters

Climate matters. It mattered to the Vikings, who settled Iceland, explored the New World, and were lured north to Greenland during a period of unusually warm weather a millennium ago. But the warmth did not last, and Viking settlements on Greenland slowly contracted as the climate cooled into the Little Ice Age (see Figure 1.1). The settlers brought farm animals into their houses during the cold winters. Eventually, the settlers ate their farm animals, then their dogs, then disappeared themselves. Climate mattered to Oklahoma farmers during the Dust Bowl years of the 1930s, when many people headed west as much of their soil headed east on withering winds. Today, with floods and drought, feast and famine, climate matters to many of us much of the time.

To be fair, climate is not everything. The victims of the Dust Bowl and of the cooling in Greenland may have contributed to their own plights through farming practices that promoted soil erosion, and the Oklahomans were fleeing a great economic depression as well as a change in the weather. While the Vikings froze out of Greenland, their "Eskimo" neighbors, the Thule Inuit, readily survived the cooling.

Still, the Assyrians, the Maya, the Anasazi, and other ancient civilizations seem to have risen to glow while nature watered their crops, and to have fallen when those crops dried out. Climate certainly mattered to them, and it certainly will matter to us.

One of the important debates of our time centers on global warming. On one side are those who argue that human-caused changes in climate will make our lives so difficult that millions of us may die, and the fabric of our civilization may be changed forever. On the other side are those who warn that efforts to avoid such a hypothetical fate may cause us to commit economic suicide and trigger the decay that we fear. To resolve this important debate, thousands of people and millions of dollars are currently devoted to the development of an "Operator's Manual" for planet Earth. Land and water, air and ice, soils and plants-if we can figure out how they work, how they are wired together and depend on each other, maybe we can then make wise decisions about global warming, ozone depletion, and other globe-girdling questions.

This effort is called Earth system science. It is mostly about observing Earth here and now, understanding modern processes, and building models of those processes to use in making predictions. But history also plays a role, in two ways. Just as the records of past peoples help us understand human society, the records of past climates help us learn how the Earth system works. And just as modern political scientists can test their ideas against the history of humans, Earth system scientists can test their models against past climate changes.

The climate models these scientists test are highly altered, computerized weather forecasting tools. If you decide to learn to forecast the weather, every day offers a new problem, and the next day provides the answer in the back of the book. A weather forecaster in training can practice predicting tomorrow's weather more than a thousand times during a college career.

Forecasting the climate is not so easy. Consider a hypothetical modeler who informs a U.S. congressional committee that disaster will arrive in a century unless we change our ways. The chair of the congressional committee is unlikely to subscribe to the doctrine of scientific infallibility, and may harrumph that economic policy should not be based on untested computer output. The real winners and losers of such a debate will be the great-grandchildren of the disputants, because modeler and congressperson alike will have been recycled themselves before the forecast can be tested.

It would be better if the scientist could also tell the congressional committee, "The model that predicts future problems has been tested by simulating many climates of the past, that were wetter and drier, warmer and colder, with greenhouse gases higher and lower than today, and the model successfully reproduced the observations. The model has been used to run simulations that started in the previous warm period and went through the most recent ice age to today, and successfully matched the changes that brought us here." The congressional committee would have a much harder time dismissing such a scientist as a crackpot. But to test our models against the history of climate, we must know that history.

These questions are far from academic. The Medieval Warm Period that opened Iceland, Greenland, and North America to the Vikings, and the Little Ice Age cooling that helped drive the Vikings from Greenland, caused glaciers to advance across farms in Norway, and allowed Hans Brinker to skate on the canals of Holland, were dwarfed by the Younger Dryas and other dramatic climate jumps that ended the last ice age, as shown in Figure 1.2. Some climate models suggest that such jumps could return, and that human activities may cause-or prevent-such a return. Many of us believe that it would be prudent to understand the large climate jumps of the past. This book is an attempt to advance that understanding in some small way.

In the next chapter, you will find a brief introduction to climate history, including the central role played by ice cores. I have been fortunate to help in reading ice-core records during three trips to Antarctica, five trips to Greenland, and countless hours in frozen laboratories. Most of us who study ice cores started out by trying to learn how the ice actually records climate, and Part II of this book provides an introduction to the many methods we use. These methods have taught us amazing things about the climate, which are described in Part III. Those results have forced us to learn about oceanic and atmospheric processes far beyond the ice sheets, as described in Part IV. Finally, all this effort gives us some insight to the future, as described in Part V.

Chapter Two

POINTERS TO THE PAST

To read the record of past climate shifts, we have to find the right history book. Humans hadn't yet mastered writing the last time the climate jumped, so we can't look up the answer in the library. Fortunately, there is a sort of "library" in ice sheets, lake beds, and the ocean floor that tells us much of what we wish to know.

Archaeologists poke around in the trash dumps of ancient humans, looking for lifestyle clues. "Modern archaeologists" do the same in modern trash dumps, sorting out the Barbie-doll heads from the half-eaten hot dogs in our garbage to learn perhaps more about us than we wish they knew. The "garbage" of the Earth system is called sediment , and it piles up in many places. Common sense and careful study allow us the "read" the records in that sediment, learning when it was deposited, and what the world was like then.

Sediment itself provides clues to its origins. A glacier scratches and polishes the stones it drags over other rocks, while the wind sandblasts the grains it piles into dunes, and mud settles in regular layers in lakes. We can easily recognize a cold climate from its glacial deposits, a dry climate from the sand dunes it leaves, or a wet climate from lake sediment.

If you sift through the lake sediment, you will usually find many other interesting things. Windblown pollen is readily identified in old sediment, and pollen from sagebrush, palm trees, or tundra flowers will tell very different stories of how dry or wet, hot or cold the climate was around the lake. Creatures living in many lakes leave their shells in the sediments, but different kinds of creatures with different shells live in salty or fresh, warm or cold lakes. Many other indicators exist, and we will discuss these indicators as they become important to our story.

Most paleoclimatologists spend their time looking at ocean sediments. The oceans cover more than two-thirds of the planet, and sediments accumulate in them almost everywhere. In comparison, lakes and sand dunes are rare, with most of the land surface slowly being washed or blown away rather than being buried in sediment. Paradoxically, it is also easier to study sediments from the ocean than from the continents. Large, specially equipped drill ships dedicated to collecting sediment cores from the ocean floor are operating year-round. But coring a small pond may involve trying to find a drill, trying to find a boat, persuading the landowner to let you in, getting drill and boat through the mud around the pond, falling out of the boat while trying to recover some mud from the bottom, trying to come back when the lake is frozen to allow coring from the ice, getting stuck in a snowdrift, and so on.

Fortunately, there are many people who seem to enjoy mud and mosquitoes, or slipping on snow, so lakes are being cored. Other records are being collected from cave formations, tree rings, and even the odds and ends that pack rats have gathered around their dens and then urinated on, preserving for posterity.

Perhaps the finest records of past climate are obtained from glaciers and ice sheets. Fully one-tenth of Earth's land surface is buried by ice, mostly in the vast Antarctic and Greenland ice sheets, but also in thousands of smaller mountain glaciers. The great ice sheets are more than two miles thick in the middle, and have been accumulating snow, and climate records, for hundreds of thousands or even millions of years. Climate scientists use drills to cut into ice sheets and glaciers, collecting ice cores. An ice core is a cylinder of ice, typically four or five inches across.

Continues...

Excerpted from THE TWO-MILE TIME MACHINE by Richard B. Alley Copyright © 2000 by Princeton University Press
Excerpted by permission. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

Full Text Reviews
Appeared in Choice on 2001-05-01:
Alley (Pennsylvania State Univ.) has produced a superlative account of a complex topic: climate change and its scientific underpinnings. The news media are intent on keeping us up-to-date on this, virtually on an hourly basis, leading to overdramatization, oversimplification, and nonsense. Conversely, the author is deeply involved in the hard science of the topic. The book discusses the Ice Ages, the solar system, glaciology, oceanography, various time scales, human impacts on climate, and especially, two-mile-deep ice cores. It is refreshingly straightforward to read, often humorous, yet still deadly serious, complete with anecdotes and understandable explanations of complex processes. The author concludes that global warming is real, driven in part by human behavior. He introduces impressive evidence for large fluctuations in the past that occurred very rapidly--within several years. The lesson is that unrestrained human interference could touch off a devastating climatic "jum p." There is an irrefutable case for more research, but especially for immediate institutional response justifiable on many grounds. This book should be read by everyone above the age of 14 and should be translated into many different languages. All levels. J. D. Ives Carleton University
Appeared in Publishers Weekly on 2000-10-30:
Recent news reports about large holes in the ice and open waters at the Arctic Circle have prompted renewed concerns about the effects of global warming. In measured tones, however, geoscientist Alley reminds us that during the last 100,000 years or so the earth has experienced a wildly varied climate pattern. Using readings of ice cores taken from Greenland, where he participated for several years in the '90s in far-reaching research projects, Alley demonstrates that periods of slow cooling and centuries of cold have been punctuated by periods of sudden warming. In fact, he notes, climatic stability is the exception rather than the rule, and he contends that the unusually warm, stable climate we have experienced for the past 10,000 years is an anomaly. Through his study of the two-mile-long ice cores, Alley reveals a number of elements that contribute to global climatic changes: wind patterns, drifting continents and ocean currents. In lively prose, he illustrates that climate can be stable, but when pushed to changeÄby either human or natural forcesÄsuch change can occur more dramatically and at a faster rate than our industrial society has ever witnessed. Yet Alley is no alarmist in predicting the ways that human activities will affect climate and climatic changes will affect humans. Although not all scientists will agree with Alley's conclusions, his engaging bookÄa brilliant combination of scientific thriller, memoir and environmental scienceÄprovides instructive glimpses into our climatic past and global future that will appeal to readers interested in how our environment affects us. (Nov.) (c) Copyright PWxyz, LLC. All rights reserved
Reviews
Review Quotes
Winner of the 2001 Book Award in Science, Phi Beta Kappa One of Choices Outstanding Academic Titles for 2001
"With a highly readable style designed to capture and stimulate the imagination of his students, Alley explains some of the complexities of Earth system science with a minimum of jargon. This book is not just for students: it will be readily accessible to a wide audience that should be aware of its contents."-- David Peel, New Scientist
"Books in which scientists write about their professional experience and describe in lay terms the stuff that makes them excited about science rarely disappoint. Richard Alley's The Two Mile Time Machine is no exception. It describes a fascinating journey into the geologic past and the history of the Earth's climate. . . . Alley ends his entertaining book by polishing his crystal ball, envisioning what the future climate will be, and what we might do about it."-- J.A. Rial, American Scientist
It is . . . refreshing to read a book that tells us in easy words, but with sufficient depth, how scientists have obtained the information about past climate change that is the basis for worries about the future. Richard Alley is a world authority in the science of ice cores and climate, and his book fills the large gap between technical and scholarly words for students of climate science and the short articles about these topics that are often found in the popular science magazines. The book addresses the interested layperson; following the story does not require special scientific knowledge. [It] is an excellent messenger of scientific endeavor and the enrichment this brings to society.
"[A] provocative little book . . . a compelling tale of climate sleuthing . . .[Alley] is authoritative without being dogmatic, concerned without being alarmist."-- Robert C. Cowen, Christian Science Monitor
"[A] superb book. . . . Alley demonstrates that the scientific understanding of climate is both a lot more complex, and a lot simpler, than public perceptions might indicate. . . . The Two-Mile Time Machine restores some of the joy of discovery that has always been present in scientific work, but is often lost amidst today's furious research pace and compressed news cycles."-- Cathering H. Crouch, Books and Culture
"A superlative account of a complex topic . . . It is refreshingly straightforward to read, often humorous, yet still deadly serious, complete with anecdotes and understandable explanations of complex processes."-- Choice
"Although not all scientists will agree with Alley's conclusions, [this] engaging book--a brilliant combination of scientific thriller, memoir and environmental science--provides instructive glimpses into our climatic past and global future . . . "-- Publisher's Weekly
"A fascinating journey into the geologic past and the history of the Earth's climate . . . Alley ends his entertaining book by polishing his crystal ball, envisioning what the future climate will be, and what we might do about it."-- J.A. Rial, American Scientist
"Alley's . . . striking finding is that the earth's climate has always been wildly variable and subject to dramatic swings--except during the past 10,000 years. So the period during which humankind has established itself across the globe and made the transition from grubby bands of hunter-gatherers to the dubious majesty of global capitalism corresponds exactly to a freakishly stable period in the earth's climate."-- Angus Clarke, The Times of London
"A fascinating first-hand story. . . . [A]n engaging narrative about the processes of obtaining, analyzing, and interpreting the ice cores. . . . Scientists, students, and the general public all need to know the present state of our incomplete understanding of the global climate system. This book provides an excellent foundation"-- Al Bartlett, American Journal of Physics
This item was reviewed in:
Booklist, October 2000
Publishers Weekly, October 2000
Choice, May 2001
To find out how to look for other reviews, please see our guides to finding book reviews in the Sciences or Social Sciences and Humanities.
Summaries
Unpaid Annotation
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 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 constructa record of such phenomena as wind patterns and precipitation over the past 110,000 years. The record suggests that "switches" and "dials" contr
Publisher Fact Sheet
A leading climate researcher describes the history of global climate change as revealed by reading the annual rings of ice cores drilled in Greenland.
Main Description
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.
Table of Contents
List of Illustrationsp. vii
Setting the Stage
Fast Forwardp. 3
Pointers to the Pastp. 11
Reading the Record
Going to Greenlandp. 17
The Icy Archives--Ice Sheets and Glaciersp. 31
Ice Age through the Ice Agep. 41
How Cold of Old?p. 59
Dust in the Windp. 71
Tiny Bubbles in the Icep. 77
Crazy Climates
The Saurian Saunap. 83
The Solar System Swingp. 91
Dancing to the Orbital Bandp. 99
What the Worms Turnedp. 109
Why the Weirdness?
How Climate Worksp. 131
A Chaotic Conveyor?p. 147
Shoving the Systemp. 159
Coming Craziness?
Fuelishp. 169
Down the Roadp. 181
An Ice-Core View of the Futurep. 185
Appendixes
A Cast of Charactersp. 193
Usage of Unitsp. 199
Sources and Related Informationp. 201
Acknowledgmentsp. 223
Indexp. 225
Table of Contents provided by Syndetics. All Rights Reserved.

This information is provided by a service that aggregates data from review sources and other sources that are often consulted by libraries, and readers. The University does not edit this information and merely includes it as a convenience for users. It does not warrant that reviews are accurate. As with any review users should approach reviews critically and where deemed necessary should consult multiple review sources. Any concerns or questions about particular reviews should be directed to the reviewer and/or publisher.

  link to old catalogue

Report a problem