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

by Richard B. Alley

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.

Genres: Science, Nonfiction, Environment, Climate Change, History, Geography, Geology

240 pages, Paperback

First published January 1, 2000

Reviews

[Jeff Koeppen · Rating 4 out of 5]

I really enjoyed The Two-Mile Time Machine, it was full of great earth science and I learned a lot about what causes changes in the climate and about past climate changes. The only complaints I have is that parts were repetitive and the writing wasn't the greatest. And I wish the illustrations would've been in color as the black and white images don't do justice to many of the photographs, it didn't matter for the many graphs and tables included. The book is relatively short - 192 pages plus an appendix, sources, and an index -and was written by a top climate scientist who presents the facts in an understandable way to lay persons with no political agenda. Just the facts, ma'am.

The title of the book refers to a two mile ice core taken from Greenland which scientists are using used to study what the past climate was like based on the composition of the rings of the ice core. The author and his fellow scientists found chemicals, pollen, dust, etc. in the various layers which gave them the ability to construct a model of the climate over 110,000 years. The variety of stuff they fined in these layers is really amazing and it's ingenious how they use the information to interpret what the world was like at a particular ring's time. One interesting discovery is that the world has experienced numerous pre-historical abrupt climate swings due to a variety of reasons and us modern humans have enjoyed a relatively stable climate for quite some time. Another thing I learned is that the wobbles in the earth's rotation and sunspot activity can cause significant changes to our climate. The author explains all this and shows how the contents of the ice core bear this out.

Especially interesting was the final chapter, "An Ice-Core View of the Future" in which the author speculates in eight pages what the climate future might hold for us and what we might do to meet it. It's an enlightening read, without all the hysterics and politicized takes we are bombarded with in the US media from both sides of the aisle.

This was my first read for Science September 2022

[Zanna · Rating 5 out of 5]

This is a fascinating chronicle of the Earth's climate, as subtly encoded in two miles of Greenland ice. Alley describes his work and that of fellow climate historians with clarity and infectious enthusiasm, painting a vivid picture of a violently fluctuating and generally inhospitable planet currently coasting through a rare period of warmth and stability that has enabled a sensitive species like us to thrive.

Alley's work makes some valuable sense of the Byzantine complexity of our climate, but while the correlations and causalities offer clues, he is too scrupulous to offer firm predictions of the consequences of humans releasing carbon into the atmosphere and pressurising other resources. However, he points out un-nervingly that the climate is 'like a drunk; left alone it sits; when pushed, it staggers'. If our climate's history has been a rough ride, there doesn't seem much hope we'll be spared the bumps in future, with ever more extreme weather on the cards: floods, droughts, hurricanes, sea level fluctuations, extreme heat and cold are all more likely in a warmer world.

[Brett Williams · Rating 2 out of 5]

Alley wrote an excellent Scientific American article in terms of information and engaging writing style (“Abrupt Climate Change,” November 2004, available online). His “Time Machine,” though occasionally informative, reads like a slow school overview: “Many clever people are studying things in ice and learning many things.” OK… Maybe this was his intent, though nowhere are we forewarned. He’s best when reporting his personal adventures in the ice-core-data-recovery field he’s part of. This book is not about much-quoted GRIP data (Greenland Ice Core Project) cataloging 123,000 years of earth’s atmospheric history in that region (I thought it was), and some 2 million-year-old plants to boot. But it does reveal findings of previous drilling, good for 110 millennia, and the Vostok ice core, extending back about 450,000 years.

Alley shows that nature and man are not without their ironies. While politicians, corporations, and talk show hosts paint their rosy picture of longer summers on the beach (ignoring these beaches may be underwater) or flourishing plant life in CO2-rich atmospheres (ignoring they may be fried in heat and dryness), as it turns out, ice ages are triggered by warming. Standby. Exciting times are coming. We’ll keep rolling the dice, but at least Alley is trying to sound the alarm. Unfortunately, as the world’s biggest offender, America heard much of this in the 60s, 70s, 80s, 90s, and 10s. While we try to change the world by collecting litter on Earth Day, those in power aren’t listening.

What’s interesting here is that Alley’s ice cores read like pages in a book, one year’s ice layer piled atop another, which trap gases, dust, and aerosols in each. According to Alley, the good news is, compared to previous interglacial warming periods, we humans have been remarkably lucky during the Holocene these last 12,000 years (since the invention of agriculture), with a relatively stable climate, except for a few hiccups. The bad news is plural. Contrary to political orthodoxy, measurable, repeatable data shows we have among the highest concentrations of CO2 in the recorded histories. The thermohaline circulation—the ocean’s equator-to-pole hot/cold exchange system—is a smoking gun in massive change, which according to NOAA data, is shutting down via ice melt freshening. And the biggest news of all: ice cores show dramatic, even catastrophic climate shift, as Alley writes, “in less time than it takes it get a college degree.” Oops. Nature has a threshold. Once tripped, it’s a long ride back—about a hundred thousand years. Buckle up.

[Molly · Rating 2 out of 5]

I must thank Doc G for the recommendation of this book. It was hard for me to read at times, but overall important content. I’m interested to know more about what advances have been made in ice core/climate science since 2000 compared to what was covered here.

[India Blake · Rating 4 out of 5]

An all-encompassing perspective, not too depressing but at times slightly overwhelming (especially in the middle sections) where the chapters are heavily science based. End section is a refreshing and often unspoken review of what lies ahead of us in terms of climate adaption and science and how we should go about this. What I learnt most from this book is the focus on oceans and ice and their involvement within the earth feedback systems, that it is more than just our atmosphere which seems to receive the most attention on these topics. Richard B. Alley is honest with his words and speaks from experiences in Greenland amongst other scientists.

[Luke · Rating 3 out of 5]

What ice cores tell us about climate history: in Greenland, annual history for 100K years, plus atmospheric gasses and hints of precipitation and seasonal changes, implying scary things about how the N Atlantic ocean current can abruptly change. The The real fun comes in being able to correlate this detailed history with others, like ocean sediment or Antarctic ice. 100k years isn't enough to look back past the last ice age cycle, but it tells us a lot about how oddly stable the last 10k years are in comparison to the preceding 90k.

[Catherine · Rating 4 out of 5]

Terrifically interesting book about our weather system, how it works, and how ice cores reveal information about it. Apparently there have been many abrupt changes in the planet's weather, like flipping a switch, and we've been living through 8000 years of an unusually stable climate. It looks like what flips the switch is a lot of fresh water pouring into the North Atlantic, which is happening. I learned a lot!

[Evelyn · Rating 3 out of 5]

A look at the history of climate change from the prospective of ice cores taken in Greenland and possible future scenarios with respect to the Earth’s climate. Although this book attempts to make the science of climate change interesting to and understandable by the layperson (non-scientist), it ultimately fails because it is tedious and rather dry reading.

[Yvonne Leutwyler · Rating 3 out of 5]

Another interesting look at climatology, past and future, via means of glacial ice cores. Generally speaking well written for the average intelligent person, but sometimes gets a bit too tangled in details.

[Murad B. · Rating 4 out of 5]

This book does a very good job of using ice cores to peer back into more recent geologic time to explore a more chaotic, less stable pre-Anthropocene time where climate changes could happen in abrupt intervals.

[Kathy · Rating 4 out of 5]

Thanks to Will for lending me this book which not only explains the fascinating science of ice, core drilling, but also provides an understandable look at the atmospheric, oceanic, and other factors that affect cyclical climate changes of the earth.

[Richard S · Rating 4 out of 5]

I was recommended a bunch of books on Climate Change and this one was the best. Very scientific, level headed, even handed.

[Bernard Lavallee · Rating 5 out of 5]

Clear and concise look at climate

Anyone with a curious nature and rational ability to analyse should read this book. I guarantee it will enlighten you.

[Sissy · Rating 5 out of 5]

An important yet brief text that anyone trying to understand climate change should read.

[Molly Driver · Rating 4 out of 5]

Very interesting to see the developement of ice cores etc. the book was very easy to understand.

[David · Rating 4 out of 5]

Page 73: "In short, a clever person can find much in ice that is interesting to study." Dr. Alley probably didn't intend this single sentence to be a summary of this book but it's a fair assessment. Dr. Alley's first-hand account of drilling 2-mile long ice cores in the Greenland and Antarctica ice sheets places the reader in the frigid cold along with the scientists. He uses simple and accessible descriptions of the complicated chemistry and measurement techniques used to "read" the ice cores, and so discover clues to earth's past climates.

[Robert Wood · Rating 3 out of 5]

Richard Alley provides a step by step analysis of how ice cores are used to understand paloeclimate. He goes from there to explain some of the mechanisms that both regulate and change climate historically within the Earth System, looking at C02, ocean currents, and other issues. It then moves into some speculation about the potential effects of man made climate change. Not a bad read, although it depended a bit much on analogy and metaphor for me, but that's more of a matter of taste, rather than anything else.

[Simon Clark · Rating 2 out of 5]

I'll be honest, I gave up on this book. Perhaps I've always approached it with the wrong attitude but I just never really got into it. Perhaps it's because I'm already familiar with a lot of the science covered, or perhaps it's covered in very dry detail, but I just didn't get a huge amount out of the book.

If you're interested in the science of how ice can yield a record of past climate, or you're interested in the science of glaciers more generally, then this could be for you. Not one that I will be revisiting however.

[Yi · Rating 5 out of 5]

this book was assigned for a seminar offered by one of my dissertation committee members, Sarah M. Aciego, at the U of Michigan. so when i started with our data on Greenland, i decided to read this book. this book is easy to read for both professionals and general public. it contains very scientific figures as well as metaphors and examples in daily life. it's good for a read for both researchers on climate, cryosphere, and geochemistry and anyone interested on those topics.

[Joannah · Rating 4 out of 5]

This book is about ice core records in Greenland… how they are collected, analyzed, and what they tell us. I thought it was well written for a general audience and would help explain climate to the average person. However, it
was written 8 yrs ago in (2000), so I think we know a bit more about climate change now.

[Lee · Rating 5 out of 5]

Comprehensive yet easy to read account of the science and findings of ice core research and how it informs our understanding of planetary climate changes on Earth. A must for anyone interested in understanding large scale climate changes.

[Garrett · Rating 4 out of 5]

Very awesome account of some reaseach done in Greenland, also contains a broader review of what we know about climate change and how we know it. No science background necessary to understand or enjoy this book.

[Maxim · Rating 4 out of 5]

The Two Mile Time Machine - Great story about the longest Greenland ice core and what we can learn from it about past climate changes from one of the main scientists who led the GISP2 project. Highly recommended if your into climate history and on the ground climate science work.

[Sally · Rating 3 out of 5]

Explains findings on climate change centering on ice cores, largely from Greenland; author part of the scientific team which gathered the first ice cores.

[Jennifer]

This was fantastically interesting but I just didn't have the time to read it and had to put it down. Would love to finish it when I get the chance.

[Pito Salas · Rating 3 out of 5]

Starts off interesting but then gets a little too comprehensive. Still I enjoyed it.

[Em Rose]

yea, i mean, why not?

[Mike Lorenzetti · Rating 4 out of 5]

You have to back up some to see the big picture. I thoroughly enjoyed his explanations of the cyclic history of ice ages and climate in general.

[Libby · Rating 5 out of 5]

What good paleoclimatologist wouldn't love this book? Read as a graduate student.

[Edward · Rating 3 out of 5]

good outline of how we get data from ice cores. bad science job of appealing for different behavior.