Paleoclimate

Paleoclimate

Michael L. Bender
Copyright Date: 2013
Edition: STU - Student edition
Pages: 320
Stable URL: http://www.jstor.org/stable/j.ctt1dr35dw
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  • Book Info
    Paleoclimate
    Book Description:

    Earth's climate has undergone dramatic changes over the geologic timescale. At one extreme, Earth has been glaciated from the poles to the equator for periods that may have lasted millions of years. At another, temperatures were once so warm that the Canadian Arctic was heavily forested and large dinosaurs lived on Antarctica. Paleoclimatology is the study of such changes and their causes. Studying Earth's long-term climate history gives scientists vital clues about anthropogenic global warming and how climate is affected by human endeavor.

    In this book, Michael Bender, an internationally recognized authority on paleoclimate, provides a concise, comprehensive, and sophisticated introduction to the subject. After briefly describing the major periods in Earth history to provide geologic context, he discusses controls on climate and how the record of past climate is determined. The heart of the book then proceeds chronologically, introducing the history of climate changes over millions of years--its patterns and major transitions, and why average global temperature has varied so much. The book ends with a discussion of the Holocene (the past 10,000 years) and by putting manmade climate change in the context of paleoclimate.

    The most up-to-date overview on the subject,Paleoclimateprovides an ideal introduction to undergraduates, nonspecialist scientists, and general readers with a scientific background.

    eISBN: 978-1-4008-4637-5
    Subjects: General Science, Physics, Paleontology
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Table of Contents

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  1. Front Matter (pp. i-iv)
  2. Table of Contents (pp. v-v)
  3. List of Boxes (pp. vi-vi)
  4. Preface (pp. vii-xii)
  5. Acknowledgments (pp. xiii-xiii)
  6. [Illustration] (pp. xiv-xiv)
  7. 1 EARTH’S CLIMATE SYSTEM (pp. 1-23)

    Earth’s climate system includes all the realms of the planet that interact to produce the seasonal march of temperature, wind, and precipitation. Most important are the atmosphere; the oceans, including their linked chemical and biological processes; and the solid Earth insofar as it influences CO2concentration in air. Atmospheric processes govern climate over time scales of a few years or less. The oceans influence climate change over periods of decades to tens of millennia. Over periods of a hundred thousand years or more, interactions between the solid Earth and the surface environment fix the CO2concentration of air and Earth’s...

  8. 2 THE FAINT YOUNG SUN (pp. 24-37)

    Early in Earth’s history, the sun’s energy output was about 30% less than at present. Temperature scales with energy flux to the one-quarter power. Early Earth temperature would thus have been lower than at present by about 8.5%, falling to 264 K (−9°C) if the greenhouse effect raises Kelvin temperature by a constant fraction. Under this condition, Earth would have been frozen over. However, there is plenty of evidence for liquid water on the surface of ancient Earth. The solution to this conundrum appears straightforward: atmospheric CO2simply rose to some high level at which Earth’s temperature was similar to...

  9. 3 PRECAMBRIAN GLACIATIONS (pp. 38-53)

    As indicated in the previous chapter, it seems that ice sheets were absent during most of Precambrian time. The Precambrian is characterized by abundant sediments that formed in a marine environment. Limestones, for example, that today are most common in low latitudes, are abundant in Precambrian sequences. Nevertheless, there is evidence for glaciation at several times during the Precambrian, including four spectacular events in which the extent of glaciers was far greater than in more recent times. The earliest known glaciation is dated to 2.9 Ga, recorded in sediments from the Mozaan Group of the Pongola Supergroup in eastern South...

  10. 4 REGULATION OF THE EARTH SYSTEM AND GLOBAL TEMPERATURE (pp. 54-72)

    Since land plants evolved about 400 Myr ago, and Earth then became biogeochemically modern, atmospheric CO2concentrations are thought to have varied by perhaps a factor of 10 or so. Concentrations fell to about 180 ppm during the recent ice ages. Most indicators suggest that they did not rise above about 1500 ppm during the last 400 Myr, although some point toward concentrations as high as 3000 ppm or more. For reference, modeling studies suggest that temperatures rise by about 2.5°C for every doubling of CO2. Thus an increase of a factor of 8 in the CO2concentration (from 180...

  11. 5 THE LATE PALEOZOIC ICE AGES (pp. 73-96)

    Earth was glaciated during much or most of an interval stretching from the Late Devonian to the Middle Permian, from about 370 to 260 Ma. Evidence for glaciation comes from two sources. First, there are “near-field” deposits on all continents that directly reflect glacial activity. Second, there are contemporaneous deposits in regions of low latitude that reflect changes in sea level associated with growth and decay of the ice sheets (sea level drops as ice sheets grow). Sea level would have changed over glacial-interglacial cycles as water was removed from the oceans to form ice sheets, then returned as the...

  12. 6 EQUABLE CLIMATES OF THE MESOZOIC AND PALEOGENE (pp. 97-124)

    Earth was substantially unglaciated during most or all of the interval beginning in the Upper Permian (260 Ma), through the Triassic, Jurassic, and Cretaceous periods of the Mesozoic Era, and the Paleocene and Eocene Periods of the Cenzoic Era, until the Eocene-Oligocene Boundary (34 Ma). Differences from modern climates were not limited to the absence of ice; the tropics were somewhat warmer than today, and the high latitudes were far warmer. While there were undoubtedly globally significant climate variations during the long interval of equable climates, the focus here is on the main characteristic of this time: Earth was warmer,...

  13. 7 THE PALEOCENE-EOCENE THERMAL MAXIMUM (pp. 125-143)

    The Paleocene-Eocene Thermal Maximum (PETM) was an event of about 200 Kyr duration, starting at the onset of the Eocene. During the event, a massive amount of CO2was rapidly released to the oceans and atmosphere. An alternative scenario for the kickoff is that CH4was released, and rapidly oxidized to CO2. The consequences were predictable and dramatic. Global temperatures rose by about 6°C. The oceans became acidified, perhaps contributing to the extinction of many deep-dwelling calcareous organisms. Also, caustic seawater dissolved CaCO3shells that normally accumulate on the seafloor at intermediate ocean depths. On land, warming led to changes...

  14. 8 THE LONG COOLING OF THE CENOZOIC (pp. 144-171)

    The oxygen isotope composition of benthic Foraminifera provides a critical tool for characterizing the cooling between the Paleogene and today, because it depends on temperature and ice volume. The first figure (fig. 6.1) of chapter 6 is an iconic graph of benthic foram 𝛿18O versus age from Zachos et al. (2001). It shows the major climate events of the last 65 Ma. The dominant feature of the climate record is the long cooling, starting around 50 Ma, that led to the ice age cycles of the Pleistocene, and to our place in an interglacial period. This long-term trend was punctuated...

  15. 9 THE ORIGIN OF NORTHERN HEMISPHERE GLACIATION AND THE PLEISTOCENE ICE AGES (pp. 172-234)

    The ice ages of the Pleistocene—the past 2.6 million years—are among the most compelling events in the history of Earth’s climate. These were periods in which Earth was remarkably transformed. During the peaks of the ice ages, glaciers covered the northern part of Eurasia and the northern and central parts of North America. In the eastern United States, their southern extent reached almost to my home in central New Jersey. Away from the ice, most continental areas were significantly colder and much drier, and the vegetation was correspondingly impoverished. The oceans cooled as well, wintertime sea ice extended...

  16. 10 RAPID CLIMATE CHANGE DURING THE LAST GLACIAL PERIOD (pp. 235-263)

    The last ice age was marked by a series of climate cycles that, while most intense in the North Atlantic, had manifestations throughout the world. These events have been broadly characterized, and their dynamics have been studied extensively with climate models. Much is known about the sequence of events associated with the cycles. However, basic causes remain to be understood.

    Many aspects of the rapid climate changes are illustrated in figure 10.1, which shows five climate records dating from 10 to 60 Ka. Moving forward in time, this interval begins shortly after the start of the last ice age, when...

  17. 11 THE HOLOCENE (pp. 264-286)

    The Holocene began, by definition, 11,700 years ago, at the end of the Younger Dryas cold excursion. It extends to the present, although the era beginning around 1850, when man first undertook activities that would have a significant impact on global climate, is sometimes called the Anthropocene. Local and regional climate changes during the Holocene are documented in a very extensive literature. Most regional changes are attributed to variations in Earth’s internal climate system (i. e., changes in regional temperature, precipitation, and other climate properties that are not driven by changes in Earth’s orbit or solar activity). In this chapter,...

  18. 12 ANTHROPOGENIC GLOBAL WARMING IN THE CONTEXT OF PALEOCLIMATE (pp. 287-294)

    Our current understanding is that, during almost all of Earth’s history, interactions between Earth’s interior, surface processes, and global climate feedbacks regulated atmospheric greenhouse gas concentrations so that temperatures were in the habitable range over most of the planet. Certainly this statement is true for the last 600 Myr, while Earth was inhabited by animals; uncertainty exists for most earlier times because we can’t accurately characterize surface temperatures.

    Evidence of ice in the tropics suggests that the climate went haywire at about 2.4 Ga (2.4 billion years ago), when atmospheric O2levels rose, and again about 710 and 630 Ma...

  19. Glossary (pp. 295-302)
  20. Index (pp. 303-306)

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