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Paleoclimates: Understanding Climate Change Past and Present

Thomas M. Cronin
Copyright Date: 2010
Pages: 448
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  • Book Info
    Book Description:

    The field of paleoclimatology relies on physical, chemical, and biological proxies of past climate changes that have been preserved in natural archives such as glacial ice, tree rings, sediments, corals, and speleothems. Paleoclimate archives obtained through field investigations, ocean sediment coring expeditions, ice sheet coring programs, and other projects allow scientists to reconstruct climate change over much of earth's history.

    When combined with computer model simulations, paleoclimatic reconstructions are used to test hypotheses about the causes of climatic change, such as greenhouse gases, solar variability, earth's orbital variations, and hydrological, oceanic, and tectonic processes. This book is a comprehensive, state-of-the art synthesis of paleoclimate research covering all geological timescales, emphasizing topics that shed light on modern trends in the earth's climate. Thomas M. Cronin discusses recent discoveries about past periods of global warmth, changes in atmospheric greenhouse gas concentrations, abrupt climate and sea-level change, natural temperature variability, and other topics directly relevant to controversies over the causes and impacts of climate change. This text is geared toward advanced undergraduate and graduate students and researchers in geology, geography, biology, glaciology, oceanography, atmospheric sciences, and climate modeling, fields that contribute to paleoclimatology. This volume can also serve as a reference for those requiring a general background on natural climate variability.

    eISBN: 978-0-231-51636-5
    Subjects: General Science, Environmental Science, Ecology & Evolutionary Biology, Paleontology, Physics

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-x)
  3. List of Tables
    (pp. xi-xii)
  4. Preface
    (pp. xiii-xiv)
  5. Acknowledgments
    (pp. xv-xvi)
  6. Abbreviations
    (pp. xvii-xx)
  7. CHAPTER 1. Paleoclimatology and Modern Challenges
    (pp. 1-26)

    The earth’s climate is changing in ways that raise fundamental questions about how the climate system functions, why these trends are occurring, and what future changes will occur. Atmospheric and ocean warming, Arctic Ocean sea-ice decline, Antarctic ice-shelf collapse, the retreat of alpine glaciers, the surging of ice-sheet margins in Greenland and Antarctica, extreme rainfall patterns, and ocean acidification are a few highly publicized trends. Are these trends typical of our planet? Can we say they are within the natural variability of our relatively mild interglacial climate state? Have similar events occurred in the past and, if so, why? Will...

  8. CHAPTER 2. Methods in Paleoclimatology
    (pp. 27-56)

    Paleoclimatology uses a diverse group of methods and strategies to reconstruct and interpret climate changes of the past. In this chapter we review major archives of climate data, geochronology and age dating methods, proxies taken from within archives that serve as surrogates of climate measurements, and paleoclimate modeling research. Paleoclimatology is a rapidly expanding field, drawing on advances in many widely disparate disciplines and technologies. This growth is evident in the recently published four-volume Encyclopedia of Quaternary Paleoenvironments (Elias 2006) and the Encyclopedia of Paleoclimatology and Ancient Environments (Gornitz 2009). Not surprisingly, there is also a great deal of specialization...

  9. CHAPTER 3. Deep Time: Climate from 3.8 Billion to 65 Million Years Ago
    (pp. 57-80)

    The earth’s 4.8-billion-year (Ga) history involved complex geological, biogeochemical, and climatic changes during its evolution from gaseous cloud to present geography and climate. Pre-Quaternary climatic (Hambrey and Harland 1981; Crowley and North 1991; Frakes et al. 1992) ocean and atmospheric evolution (Holland 1984, 2003; Grotzinger 1990; Kasting and Howard 2006) has long attracted a variety of specialists, but it is mostly the domain of geologists, geochemists, paleobiologists, and geophysicists. More recently, it has gained the attention of paleoclimate modeling groups because of the importance of understanding the dynamics of extreme climates and the role of atmospheric carbon dioxide (CO2) and...

  10. CHAPTER 4. Cenozoic Climate
    (pp. 81-112)

    The earth experienced global cooling during the Cenozoic era, the last 65 million years (Ma), culminating in extensive polar and midlatitude continental ice sheets during glacial periods of the last half-million years. Cenozoic climate evolved in steps, apparently crossing thresholds into colder climate regimes with greater pole-to-equator thermal gradients, rapid growth of the Antarctic and northern-hemisphere continental ice sheets, and changes in atmospheric carbon dioxide (CO2) concentrations. Revolutionary tectonic, oceanographic, biogeochemical, and atmospheric changes contributed to this transformation, at times leading to extremes in global climate that had implications for future climate. Fischer (1981) called the Cenozoic transition from a...

  11. CHAPTER 5. Orbital Climate Change
    (pp. 113-148)

    The orbital theory of climate explains glacial-interglacial cycles and other environmental changes caused by changes in geographical and seasonal insolation from variations in the earth’s orbital geometry over tens of thousands to hundreds of thousands of years. In its basic form, orbital theory holds that three aspects of the earth’s orbit vary because of gravitational forces in the solar system and influence climate in a wide variety of ways. The first two—the tilt of the earth’s axis, or obliquity, and the precession, broken down into axial precession (wobble) and precession of the equinoxes (the shifting of the earth’s orbital...

  12. CHAPTER 6. Glacial Millennial Climate Change
    (pp. 149-184)

    In this chapter we describe evidence and possible causes for what are referred to as millennial climate events during the last glacial interval between about 115,000 and 22,000 years ago, after the peak interglacial warmth of Marine Isotope Stage (MIS) 5e and before the last deglaciation. This type of climate variability is, in many ways, unique in that the earth’s climate state changes rapidly, within de cades, during a prolonged glacial period and persists in a new, fairly stable climate state for 500 years to several millennia. Millennial climate events have global impacts but occur at suborbital timescales and cannot...

  13. CHAPTER 7. Millennial Climate Events During Deglaciation
    (pp. 185-214)

    The transition from the Last Glacial Maximum (LGM) to the Holocene interglacial is arguably the geological interval most studied by paleoclimatologists. The last deglaciation took place from ~22 ka until 11.5 ka, when the earth’s mean annual atmospheric temperature rose about 5°C and there was regional high-latitude warming exceeding 10°C and smaller but significant tropical and deep-sea warming of 2–4°C and 1–2°C, respectively. Deglaciation also brought major changes in the global hydrological bud get and regional precipitation patterns. Most of the world’s large northern-hemisphere ice sheets in Eurasia and North America, the Patagonian Ice Sheet, and parts of...

  14. CHAPTER 8. Holocene Climate Variability
    (pp. 215-242)

    This chapter deals with the challenging subject of climate change during the Holocene interglacial period covering the past 11.5 ka. The Holocene epoch poses unique problems for paleoclimatology. One unique aspect of the Holocene is that the past few thousand years constitute the benchmark against which climatologists differentiate 20th-century human-induced climate change from natural variability. Compared to global climate changes over orbital and millennial timescales, the signal-to-noise ratio for Holocene climate variability is relatively small. For example, global mean temperature has oscillated by only 0.5–1°C during the past few millennia, whereas there has been a 5°C or more mean...

  15. CHAPTER 9. Abrupt Climate Events
    (pp. 243-272)

    We devote a full chapter to the important topic of abrupt climate change because the scientific community, as well as society in general, must—through choice or necessity—confront the issue of whether today’s climate is experiencing an abrupt climatic transition due to human activities. At its simplest, the question is this: Are rapidly rising green house gas concentrations and large-scale land use disturbing the global hydrological cycle, pushing global climate into a new state, or will such a change happen soon? Stocker and Marchal (2000) phrased the question another way: Where is the current climate state situated on the...

  16. CHAPTER 10. Internal Modes of Climate Variability
    (pp. 273-294)

    Quantifying the human fingerprint on climate and predicting future climate changes are two of the greatest environmental challenges facing society. There is an urgency to distinguish climate change caused by human activity, such as fossil-fuel burning and land-use change, from that caused by natural processes. In fact, there is an entire branch of climate science devoted to detection and attribution (D&A) of recent climate change (International Ad Hoc Detection and Attribution Group 2005). Detection deals with the identification of a trend and attribution addresses its causes.

    As seen in Chapter 1 of this volume, climatologists divide causes of climate change...

  17. CHAPTER 11. The Anthropocene I: Global and Hemispheric Temperature
    (pp. 295-318)

    In the year 2000, atmospheric chemist Paul Crutzen of the Max Planck Institute for Chemistry and biologist Eugene Stoermer of the University of Michigan assigned the term Anthropocene to designate the period of time since the late 18th century when human beings began to have an impact on the earth’s atmospheric concentrations of carbon dioxide (CO2) and methane (CH4) (Crutzen and Stoermer 2000). Although Crutzen and Stoermer recognized that the date they chose for its onset was somewhat arbitrary, the Anthropocene nonetheless roughly coincided with the initial rise in atmospheric green house gas concentrations recorded in ice cores, the invention...

  18. CHAPTER 12. The Anthropocene II: Climatic and Hydrological Change During the Last 2000 Years
    (pp. 319-348)

    This chapter addresses trends in parts of the climate system other than surface air temperature for the past ~2000 years. We focus on atmospheric records of precipitation, drought, and tropical cyclone activity; ocean records of temperature, salinity, circulation, and chemistry; polar sea ice; and alpine glaciers, ice sheets, and sea-level change. Emphasis is mainly on regional climate variability, its context in the global system, and evidence for human influence on climate. We begin with a brief discussion of the scientific community’s attempt to address the issue of human-induced climate change, its manifestations, and impacts through detection and attribution studies introduced...

  19. Epilogue
    (pp. 349-350)

    Natural processes in the oceans, atmosphere, ice, organisms, and lithosphere left us an archival history of the earth’s climate, and, thanks to the geoscientists committed to unraveling these archives, we now know an awful lot about it. Ice sheets and glaciers catastrophically melt, sea level rises at rapid rates, temperature spikes in a lifetime or less, ocean circulation alters global heat transport, biogeochemical cycles undergo drastic extremes, persistent droughts affect human cultures, and ecosystems and biomes are often totally rearranged. This collective body of geological knowledge, hardly imagined a few decades ago, proves beyond a reasonable doubt that the earth’s...

  20. APPENDIX: Paleoclimate Proxies
    (pp. 351-358)
  21. References
    (pp. 359-432)
  22. Index
    (pp. 433-444)