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...

Years Ago

Antarctic ice cores show large CO2 drops during the last 2,000 years compared to the long-term rising trend (shaded). full-glacial and full-interglacial climates. During some of these oscillations, huge numbers of icebergs broke away from the coastal margins of the ice sheets, floated out into the Atlantic, and dropped enormous quantities of rock and mineral grains into the ocean sediments. These relatively brief oscillations are superimposed on top of the slower, longer-term climatic...

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...

Years

Natural (orbitally driven) changes in solar radiation caused the methane maximum 11,000 years ago and the decrease until 5,000 years ago, but humans account for the anomalous increase since that time. One obvious thing to check was the status of the two major methane-generating reservoirs, the tropical and boreal wetlands. Had one or both of them begun to disobey the normal (natural) control by solar heating, even though they had behaved so predictably for so long But this was not the...

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...

Millions of Years Ago

The combined effect of changes in the eccentricity of Earth's orbit and in its slow wobbling motion cause changes in the amount of solar radiation received at low and middle latitudes at a 22,000-year cycle, with the size of the cycles varying at 100,000 years. 6 percent farther away at the other extreme compared to a perfectly circular orbit. Precession makes these inequalities in Earth-Sun distance shift slowly around the eccentric orbit so that over thousands of years they occur during...

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...