Future Warming Large Or Small

The size of the future greenhouse warming hinges mainly on two issues (1) How high will the concentrations of CO2 and equivalent greenhouse gases rise because of human activities (2) How sensitive is the climate system to those increases The answers to both of these questions have significant uncertainties attached. It took millions of years for natural processes to store three carbon-based energy sources in Earth's sedimentary rocks. The carbon stored in coal originated in vegetation that...

But What About Those Co2 Wiggles

Most of the Antarctic ice sheet is a high polar desert receiving no more than an inch or two of snowfall each year, the polar equivalent of the arid core of the Sahara. Ice cores from such locations cannot capture the detail needed to reveal the short-term variations in CO2 and other gas and solid constituents that occur over centuries or decades. But along the lower margins of the ice sheet, snowfall is heavier, and in favorably sheltered sites it is blown into thicker piles by strong winds....

Bibliography

The following volumes were useful sources in compiling this book and are written in a general style that should be accessible to nonspecialist readers. Alvarez, W. T. rex and the Crater of Doom. Princeton Princeton University Press, 1997. Chorlton, W. Ice Ages. Alexandria, VA Time-Life Books, 1983. Imbrie, J., and K. Imbrie. Ice Ages Solving the Mystery. Short Hills, NJ Enslow, 1979. Tudge, C. The Time before History. New York Touchstone, 1997. Diamond, J. M. Guns, Germs, and Steel. New York W....

Challenges And Responses

Most new scientific ideas follow a typical sequence. After the thesis (publication of the new hypothesis) comes the antithesis (evaluation and criticism by the scientific community), and later, for those hypotheses that survive close scrutiny, the synthesis (refining or reshaping of the hypothesis into a form that addresses the criticisms and satisfies a wider range of observations). At this point, usually years later, the hypothesis may come to be called a theory. In the case of my hypothesis,...

Globalchange Science And Politics

The future global warming will be large, but will it be bad or good In terms of its effects on people, it depends. It depends on such things as who you are, where you live, what you do for a living, your ethical and aesthetic values, and your financial and economic status. Because these considerations lead to different value judgments, this question has no single answer. Most climate scientists, aware of the limits of scientific knowledge and wary of complex value judgments, attempt to balance...

Have We Delayed A Glaciation

The evidence seemed clear human activities linked to farming had taken control of the trends of two major greenhouse gases thousands of years ago, forcing their concentrations to rise when nature would have driven them lower. The net impact of humans through time (fig. 10.1) was a long slow rise in greenhouse-gas concentrations prior to the industrial era, and then much more rapid increases during the last 200 years of industrialization. Scientists use a convenient standard to evaluate the...

Greenhouse Warming Tortoise And Hare

Readers with a sharp eye may have been puzzled by a part of chapter 10 that seemed contradictory. Figure 10.1 showed that the relatively modest rise of greenhouse gases estimated to have been caused by humans before the Industrial Revolution (40 parts per million for CO2 and 250 parts per billion for methane) led to a relatively large rise in global temperature (0.8 C), while the larger industrial-era rise in gases (now almost 100 parts per million for CO2 and 1,000 parts per billion for...

Contents

Part One What Has Controlled Earth's Climate Slow Going for a Few Million Years 17 Linking Earth's Orbit to Its Climate 25 Orbital Changes Control Ice-Age Cycles 35 Orbital Changes Control Monsoon Cycles 46 Part Three Humans Begin to Take Control Early Agriculture and Civilization 65 Have We Delayed a Glaciation 95 PArT Four Disease Enters the Picture But What about Those CO2 Wiggles 119 The Horsemen of the Apocalypse Which One 127 Pandemics, CO2, and Climate 139 Greenhouse Warming Tortoise and...

Epilogue

Global change a term that encompasses the size and impact of future climate change caused by greenhouse-gas emissions from human activity is one of the most highly polarized topics in all of science. Scientific assessments of this impact have direct implications for key economic areas such as transportation, electricity generation, and heating and air conditioning. Large amounts of money hinge on governmental decisions about what energy policy to adopt in response to the problem, and this link...

Info

Snow cover on land and sea-ice cover on the ocean will expand, especially at frigid latitudes near and poleward of the Arctic Circle. The greater expanses of these bright white surfaces will reflect much more incoming solar radiation than the dark-green land surfaces and deep-blue ocean they replace. Land and water are heated by the solar radiation they absorb, but snow and ice reflect almost all incoming radiation back to space. In this way, increased expanses of snow and sea ice in the Arctic...

Stirrings Of Change

In almost 2.5 million years, hominids had moved only slightly beyond the most primitive level of Stone Age life, adding control of fire and gradually more sophisticated stone tools to their meager repertoire of skills (table 6.1). But once our species appeared, 150,000 to 100,000 years ago, the pace of change quickened, at least by comparison to the nearly undetectable tempo of previous times. By 50,000 years ago, we see the first real evidence of human creative potential emerging in the...

Orbital Changes Control Iceage Cycles

Imagine standing on a tropical island in the Pacific, one of those coral atolls that barely rises high enough above sea level to avoid being inundated by passing typhoons. Now imagine standing in that exact same spot 20,000 years ago. What would be different The waves would still be crashing against the edges of that same island, but now some 375 feet below the place you stand. The difference would be the result of water taken from the ocean and stored in ice sheets. After almost 40 years'...

Millions of Years

Gradual changes in the tilt of Earth's axis relative to its orbit around the Sun at a cycle of 41,000 years alter the amount of solar radiation that arrives at high latitudes. Over long time scales, Earth's angle of tilt does not remain constant. In the 1840s French astronomer Urbain Leverrier found that the gravitational attraction of large planets (mainly Jupiter) causes Earth's tilt to vary within a range of 22.2 and 24.5 over a cycle that is 41,000 years long. Every 41,000 years, the...

The Horsemen Of The Apocalypse Which

Historians have long sensed that the last centuries of the Roman era, and those that followed, were something of a reversal in the onward and upward march of human progress typical of previous centuries, at least in Europe. The Romans had for a while achieved a level of engineering technology and general prosperity that would not be repeated again in most of the West for over a millennium. Aqueducts brought to their cities fresh water of a quality not equaled until less than 200 years ago in...

Taking Control Of Methane

Several years ago, just as I was about to retire from the Department of Environmental Sciences at the University of Virginia, I noticed something that didn't make sense. The methane concentration in the atmosphere during the last 5,000 years had risen, when everything I knew about the climate system told me that it should have fallen. My expectation that the methane concentration should have been dropping came directly from John Kutzbach's theory of the orbital control of monsoons (chapter 5)....

Preface

The research that led to this book began when I was a professor in the Department of Environmental Sciences at the University of Virginia, following my earlier career at Lamont-Doherty Observatory of Columbia University. I was able to interest undergraduate student Jonathan Thomson in a term-length research project that explored a mystery that had puzzled me earlier the fact that methane concentrations in the atmosphere have risen for the last 5,000 years when everything I knew about the...

Taking Control Of Co2

Convinced that humans had taken control of the atmospheric methane trend by 5,000 years ago, I began to wonder if we might have had a significant effect on carbon dioxide millennia ago. Because CO2 is a more abundant greenhouse gas than methane, and its effects on climate are generally larger, this question was potentially more important than the methane story, but for a while I resisted pursuing it. One reason for the delay was that CO2 changes are more difficult to interpret than those of...

Years

Natural processes caused the atmospheric CO2 peak nearly 10,500 years ago and the subsequent decrease until 8,000 years ago, but humans have caused the anomalous CO2 increase since that time. was the case with methane, this rise may not be the full anomaly. It is also necessary to try to take into account the amount by which CO2 would have dropped if natural processes had continued in control during the last 8,000 years. We can do this by examining the previous interglaciations to find the...

What Has Controlled Earths Climate

Imagine Earth viewed from a satellite. Blue oceans cover more than two-thirds of the planet and brown or green land the rest. White ice sheets over a mile thick bury a small fraction of the land (Antarctica and Greenland). Whitish sea ice forms a cap a few feet thick over the polar oceans, and its seasonal fluctuations in the two hemispheres occur at exactly opposite tempos (one large when the other is small). Surrounding everything is a thin blue envelope of atmosphere with swirls of clouds....

Years Ago

Changes in summer solar radiation nearly 400,000 years ago are the closest analog to July radiation changes during the last several millennia. hypothesis. The greenhouse-gas increases during the last few thousand years have indeed been anomalous compared to the natural behavior of the climate system. And if these increases were not natural, they must have originated from human activities. Yet at first this evidence appeared to conflict with other analyses of this same interglaciation...

Linking Earths Orbit To Its Climate

The realization that small changes in Earth's orbit might have regular and predictable affects on climate originated just over a century and a half ago. It came about from a convergence of knowledge in two very different disciplines the still-young science of geology and the somewhat older field of astronomy. In the middle 1800s geologists first proposed that great, mile-high ice sheets had existed in large areas of the Northern Hemisphere and had disappeared in the not-too-distant past. These...

Year

The number of weeks per year that sea ice jammed northern Iceland ports increased for several centuries but then dropped sharply during the 1900s. But records of Icelandic sea ice and alpine glaciers speak for only a small part of Earth's surface, and local records may not represent the larger picture. For example, the winter of 1976 1977 was very cold by normal eastern United States standards, with harbors choked with ice south to New York and beyond. Two decades later, the winter of...

Humans In Control

During the late 1700s and 1800s, the world entered the industrial era. Technological innovations such as engines powered by steam and later by gasoline transformed our ability to produce and make use of inexpensive power. The invention of the reaper and other devices transformed agriculture, enabling farmers to turn the deep roots of prairie grasses and plow the fertile soils. The population of the planet exploded from 1 billion in 1850 to 6 billion by 2000. The environmental consequences of...

Afterword To The Princeton Science Library Edition

Five years have passed since I wrote Plows, Plagues, and Petroleum (first published in 2005), and this new Princeton Science Library edition gives me an opportunity to look back on the way the science covered in the book has evolved. Because parts 1 and 2 provided fundamental background information, little has changed regarding the issues they discussed. Part 5 largely dealt with modern and future climate, and the most noteworthy shift in the last five years has been the development of an even...

Greater moisture 9000 years ago than today

Summer insolation values 8 percent higher than today produced summer monsoons stronger than today nearly 10,000 years ago across North Africa and southern Eurasia. This connection is supported by model simulations (A) and by evidence from Earth's surface (B). concluded that a major source of the methane changes measured in Antarctic ice must be changes in the strength of the tropical monsoons. The reason for the connection between monsoons and methane is shown in figures 5.1 and 5.2. When...

Millions of Years Ago

Large ice sheets first appeared in the Northern Hemisphere nearly 2.75 million years ago and grew and melted at the 41,000-year cycle of orbital tilt until about 0.9 million years ago. Since that time, the major cycle of ice-sheet changes has been at a cycle of 100,000 years. By the 1980s, a ship funded by an international scientific consortium had begun applying techniques borrowed from the oil industry to drill sediment sequences penetrating thousands of feet into the sea floor and...

Consuming Earths Gifts

Even though I have made the case that future climate change is likely to be large (chapter 16), I do not rank the oncoming global warming as the greatest environmental problem of our time. Other environmental issues seem to me far more immediate and pressing, and in the future I suspect our concerns will focus heavily on the eventual depletion of key resources. One theme of this book is that humankind has been steadily transforming Earth's surface for some 8,000 years, initially in Eurasia and...

Climate And Human History

Most scientists accept the view that human effects on global climate began during the 1800s and have grown steadily since that time. The evidence supporting this view looks quite solid two greenhouse gases (carbon dioxide, or CO2, and methane, or CH4) that are produced both in nature and by humans began unusual rises like the pattern shown in figure 1.1A. Both the rate of change and the high levels attained in the last 100 to 200 years exceed anything observed in the earlier record of changes...

From The Past Into The Distant Future

Scandinavia Ice Sheet 8000

The role of humans in Earth's climatic history falls into four phases (fig. 17.1). Until 8,000 years ago, nature was in control. Even though our remote prehuman precursors had been present on Earth for several million years, nature alone drove climate change. Even when our fully human ancestors appeared sometime after 150,000 years ago, our impact on the global landscape was still trivial. People used firesticks to burn grasslands or forested areas in order to drive game or provide open areas...

Orbital Changes Control Monsoon Cycles

One of the bleakest places on Earth today is hyperarid Sudan, south of Egypt. Dry winds blow sheets and dunes of sand across the landscape, and almost nothing lives there. But satellite photos and images from heat-sensing devices show subsurface traces of streams and rivers that once flowed eastward to join the Nile River in its northward course from well-watered source areas in the highlands of East Africa. Once, this desert area was green, with broad grasslands and tree-lined waterways...

William F Ruddiman

Princeton university press princeton and oxford Copyright 2005 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire 0X20 1TW First printing, 2005 First paperback printing, 2007 First Princeton Science Library edition, with a new afterword, 2010 ISBN 978-0-691-14634-8 The Library of Congress has cataloged the cloth edition of this book as...

Figure Sources And Credits

Ruddiman, The Anthropogenic Greenhouse Era Began Thousands of Years Ago, Climatic Change 61 (2003) 261 93. Figure 2.1. Adapted from P. B. deMenocal, Plio-Pleistocene African Climate, Science 270 (1995) 53-59. Figure 2.2. Adapted from A. C. Mix et al., Benthic Foraminifer Stable Isotope Record from Site 849 0-5 Ma Local and Global Climate Changes, Ocean Drilling Program Scientific Results 138 (1995) 371-412. Figure 3.1. Adapted from W. F. Ruddiman, Earth's Climate...

Pandemics Co2 And Climate

Dead Lichen Halos Baffin Island

The correlation between pandemics and drops in atmospheric CO2 concentrations was suggestive, but what was the connection How could plague and other diseases cause the drops in CO2 Part of the answer to these questions comes from historical records summarized in chapter 13. These records document abandonment of farms and farm villages on a massive scale during and after all three major pandemics. In the wake of the European plagues, abandoned farms are described as having gone to waste or ruin....

Slow Going For A Few Million Years

Somewhere in East Africa, buried under a thin layer of soil for protection from curious eco-tourists, lie fossilized footprints 3.6 million years old. Soon after a long-ago volcanic eruption, two adult creatures walked across a bed of cooled and rain-moistened volcanic ash, leaving the marks of their feet. Occasionally protruding outside one of the two sets of footprints are extra toe marks, as if a large child was also part of the group, walking along and placing its feet inside the marks made...

Early Agriculture And Civilization

Agriculture originated independently in several regions within the last 12,000 years. The two earliest developments, in the Fertile Crescent region of Mesopotamia at the eastern end of the Mediterranean and in the Yellow River Valley in northern China fig. 7.1 , were to have the largest impact on early civilization. Agricultural discoveries began thousands of years later in other regions, including the Central American lowlands, the high terrain around the Peruvian Andes, and the tropics of...