Fundamental Tenets Of Modern Orbital Theory
The slow but perceptible march of earth's orbital orientation conveyed in the Jia-Yi Monument has been formally described in many papers on the orbital theory of climate change Imbrie et al. 1984 Pisias and Imbrie 1986 87 Berger et al. 1992 . Berger 1984 and Berger and Loutre 1991 describe the celestial mechanics of earth's orbital geometry as it relates to climate change. In this section, I describe briefly the basic tenets of the theory derived from these papers. Understanding how earth's...
Biological Concepts In Paleoclimatology
This section illustrates the role of biology in paleoclimatology by describing four interrelated concepts that permeate ecological and evolutionary biology the niche, the community, the biome, and the evolutionary concept of adaptation to the environment. Obviously, these concepts are neither all-inclusive nor totally distinct from one another. They incorporate, however, a large amount of theory and principles useful in climate studies. The first three concepts relate to successively higher...
Age Models
Many paleoclimate studies proceed by first developing a chronology, usually referred to as an age model figure 2-7 . An age model is just that, a model constructed from the various dating and correlation tools described above. Age models for some of the more important paleoclimate records seem to take on lives of their own, evolving as more data accumulate or dating and correlation methods improve. One notable example is the age model for the Vostok ice core from Antarctica, a keystone climate...
DeepOceanic Circulation
Deep-ocean circulation is referred to as thermohaline or density-driven circulation. The ocean's deep water masses form in high latitudes, mainly the Greenland-Iceland-Norwegian Nordic Seas and the Labrador Sea in the North Atlantic regions, called North Atlantic deep water NADW , and around the periphery of Antarctica, called Antarctic bottom water AABW . Note in figure 2-3 that relatively warm 2.5-4 C NADW is underlain by colder 0-2 C AABW. Two major processes are responsible for...
DeepOcean Circulation and Benthic Environments
Efforts to understand deep gt 2500 m and mid-depth 1000-2500 m oceanic circulation over orbital time scales complements studies of surface oceanic conditions. Deep-ocean circulation changes over orbital time scales are important elements in orbital theory because the deep sea provides a way to translate regional insolation changes affecting high latitudes of the Northern Hemisphere into a global climate signal via the ocean's thermohaline circulation. Recall from chapter 2 that deep-water...
The Oceans
The oceans are the world's largest reservoir of heat derived from solar insolation. Ocean circulation is the most important process transporting solar energy from low to high latitude areas and, through deep-oceanic circulation, around the world. Oceanic circulation is driven mainly by wind stress, heating and cooling, and evaporation and precipitation, all ultimately controlled by solar radiation and linked to atmospheric circulation. Major surface ocean currents are wind driven, created by...
North Atlantic SeaSurface Temperatures and Pelagic Ecosystems
There are clear linkages between variability in physical aspects of oceanic systems and variability in biological aspects of pelagic marine ecosystems as measured by biomass and other properties at various temporal and spatial scales Mann and Lazier 1996 . McGowen 1990 pointed out that the complex structure and function of pelagic marine ecosystems made mathematical modeling of fluxes of energy and matter difficult. Rather, McGowen 1990 suggested a phenomenological approach as an alternative...
Principles of Paleoclimatology Hyh
theories too do not evolve piecemeal to fit facts that were there all the time. Rather, they emerge together with the facts they fit from a revolutionary reformulation of the preceding scientific tradition, a tradition within which the knowledge-mediated relationship between the scientist and nature was not quite the same. INTRODUCTION A MULTIDISCIPLINARY APPROACH IN PALEOCLIMATOLOGY The outback of western Australia has been home for millions of years to endemic flightless birds such as the...
LowLatitude Climatic Cycles in the Indian Ocean Monsoon Equatorial Pacific and
Tropical and subtropical oceanic pelagic ecosystem variability is also characterized by orbital frequencies during the past few million years. Moreover, tropical and subtropical oceanic biomes probably play a reciprocal role in long-term climate change by regulating atmospheric-ocean carbon fluxes during large-scale climatic oscillations. For example, near-surface productivity changes, which vary seasonally due to wind-induced upwelling, also vary over glacial-interglacial time scales. Glacial...
HypotheticoDeductive Testing of Biological Theories
We have seen that biological sources of climate history span various hierarchical levels, from the cell, whole organism, population, species, community, ecosystem, or biome. A third reason to focus on the biotic aspects of climate change is that the temporal dimension provided by paleoclimatology provides a means to test ecological and evolutionary theories about these entities, just as it offers a means to test theories of climate change. Most ecological and evolutionary research, like...
The Deepsea Record Of Orbital Climate Change
Testing orbital theory requires a more continuous temporal record of climate than that provided by the snapshot-like sea-level record of coral-reef tracts. The advent of deep-sea sediment coring, foraminiferal micropaleontology, and stable isotope geochemistry provided continuity of climate indicators. Continuity is a prerequisite for tests of periodicity, an inherent part of Milankovitch's theory. The fairly continuous record of ocean history afforded by micropaleonto-logical data yielded two...
Dating and Correlation of Climate Change The Geological Time Scale
All paleoclimatology is firmly rooted in the standard geologic time scale accepted by most geologists who study earth history. Table 2-3 lists the major subdivisions of the geological stratigraphic column. Throughout most of this book, the focus is on climates of the Cenozoic the last 66 million years of earth history especially the past 5 million years of Pliocene and Quaternary history. References will also be made to long-term climate history, which are described in general surveys of...
Reductionism and Holism
The fourth reason for devoting attention to biological processes involves a discussion of the underlying philosophical basis of paleocli-matology. Paleoclimatology is essentially a hybrid science. It is at once an observational and a historical science that involves natural climatic experiments'' of the past, often measuring biological and biochemical parameters as evidence, to test theories about the causes of climate change. At the same time, it is a quantitative predictive science devoted to...
Indicator Species and Fossil Assemblages
The species and assemblages of about a dozen major groups are used routinely in paleoclimatology, and many more minor fossil groups are used less commonly figure 2-8, table 2-7 . What makes a species a good proxy of climate parameters Although the answer to this question varies widely from group to group, Coope 1977 provides five attributes of species of Coleoptera beetles that also apply to most other groups evolutionary stability, morphological complexity species-specific fossilizable...
Oxygen Isotopes and Ice Volume
Dated emerged coral reef tracts compose only half the story linking global sea level to orbital forcing of climate change. The hypothesis that tropical reef tracts formed during periods of high insolation and low global ice volume was developed in tandem with evidence for icevolume changes derived from the deep-sea oxygen isotope record of foraminifera. The oxygen isotope stage system that forms the basis of the SPECMAP chronology also provides a means to estimate firstorder ice volume changes...
Major Forcing Mechanisms
Two central goals of paleoclimatology are to document patterns of past climate change that is, the how and when of climate change and to infer why climate changes. It is therefore important to conceptualize the distinction between reconstructed patterns of climate change, which may be exceptionally well-documented by multiple-proxy data in several regions, and the processes that may have produced those patterns. The processes that cause climate to change are both external and FIGURE 2-4...
Radiometric Dating
Several naturally occurring, unstable isotopes of certain elements are frequently used to determine the age of climate-related phenomena. The age of geological material can be computed from the ratio of parent to daughter isotopes using the radioisotopes' half-life, the time it takes for half the original number of atoms to decay. Radioactive iso-topic decay occurs when an isotope of an element undergoes spontaneous emission of either electromagnetic radiation or particles. Two radioactive...
Contemporary Issues in Climate Change The Role of Paleoclimatology
We attach the utmost importance to a full understanding of the physical, chemical, and biological processes by which subtle changes in insolation are amplified to induce long-term changes in global climate. For this, a knowledge of the sequences of events and the exact timing of forcings and of the climate responses in various parts of the earth system is essential. As the Royal Mathematician living near Prague, in what is now the Czech Republic, Johannes Kepler's job in the early seventeenth...
Principles of Paleoclimatology Magnetostratigraphy and Biostratigraphy
Magnetostratigraphy is the application of reversals in the earth's magnetic field to the correlation of sediments and other rocks. Because the earth's magnetic polarity occasionally reverses itself quickly, the magnetic polarity of minerals in rock sequences preserves magnetic polarity reversals as near-instantaneous time horizons that can be used to correlate rocks and climate history globally. A standard magnetostratigraphic scheme is used in most paleoclimate studies of Cenozoic sediments....
Reciprocity Climate Change and Biological Processes
A second reason to focus on biology is the reciprocity between climate change and biological processes. Just as climate change can have severe impacts on biotic systems, biotic activity likewise influences climate. The study of climate history thus requires an understanding of the inherent role that organisms play in biogeochemical processes that link the atmosphere and ocean in the flow of energy and matter. An obvious example of how biotic activity regulates climate is the role in the storage...
The Fossil Record Sensu Latu
Why stress a biological focus in paleoclimatology, a field traditionally viewed as a discipline of the physical sciences There are four overarching reasons to bring a biological focus into our attempts to understand climate change. The first reason relates to the prior discussion of tropical glacial-age paleoclimatology. Much if not most evidence for climate change is based on information derived from biological sources preserved in the fossil record. In paleoclimatology, fossil record refers...
preface
Most scientists can recall an incident, probably insignificant at the time it happened, when their interest in natural history was stirred. I had two such moments. First, when I was six or seven, I asked my dad how the immense rocks had found their way into my Connecticut back yard. He explained that they had been carried there by great glaciers thousands of years ago. I never gave a second thought to the rocks and glaciers, nor to the climate changes that ultimately were responsible for them,...
Floating Time Scales
A floating time scale refers to situations in paleoclimatology in which a high-resolution, often annually resolved climate history can be obtained from a period for which the absolute and or calendar year age remains uncertain. A good example of a floating time scale is found in the study of early Holocene coral geochemistry from the island of Vanuatu in the southwest Pacific Ocean by Beck et al. 1992, 1997 . These authors studied strontium-calcium Sr Ca ratios in five coral colonies dated...
Biological Principles In Paleoclimatology
Australian emus, prymnesiophyte algae, Porites coral reef colonies, and South American trees may seem to have little in common. Actually, all are biological groups adapted to live in the modern tropical climatic zones characterized by relatively warm year-round temperatures. All four also have organic parts that fossilize easily. A third commonality is that emu eggshell, prymnesiophyte, and coral skeleton chemistry, as well as pollen from South American trees are all pa-leoclimatic proxies used...
Hutchinson Niche Hypervolume
In his classic paper Homage to Santa Rosalia,'' G.E. Hutchinson 1959 asked the simple question Why are there so many species '' Hutchinson's papers spawned an explosion in theoretical ecology that reached a zenith in seminal publications by Robert MacArthur 1972 MacArthur and Wilson 1967 , Robert May 1981 , and many other ecologists see Cody and Diamond 1975 . Much of this effort was devoted to expressing mathematically the relationships between competing species and populations and to...
Other Dating Methods
Other dating techniques applied to date soils, loess, and tephras are described in many books and in the pages of journals such as Quaternary Chronology. Methods such as amino acid racemization, optically stimulated luminescence OSL , thermoluminescence TL , and electron spin resonance ESR are usually applied to the Quaternary dating of material older than 35 ka, and younger than about 1 Ma, an interval when radiocarbon or U-series methods are inapplicable. TL dating of beach sands and loess,...
contents
1. Contemporary Issues in Climate Change Paleoclimatology The Time Dimension 4 Early Thoughts and Contemporary Sources 7 A Brief Outline of This Book 11 2. Principles of Paleoclimatology 14 Introduction A Multidisciplinary Approach Defining the Principles of Paleoclimatology 17 Causes of Climate Change The Climate System 20 Time Is of the Essence 38 Strategies to Study Climate History 52 The Development of an Annual-Resolution The Evolution of Glacial-Age Climatology 73 3. Vital Effects...
Recent Developments in Dating Coral Reefs and Sea Level
Rapid progress in dating coral reefs in the last decade, largely through the application of TIMS dating and new stratigraphic analyses, has renewed debate about orbital theory and sea-level change. New data sets include corals from Barbados Edwards et al. 1987, 1991 Bard et al. 1990b, Gallup et al. 1994 North America Stein et al. 1991 Muhs 1992 Muhs et al. 1994 Houtman Abrolhos Islands off western Australia Zhu et al. 1993 , New Guinea Stein et al. 1993 eolianites, or beach deposits and notches...
Niche in Paleoclimatology
In paleoclimatology, the niche concept is manifested as one of the discipline's most fundamental principles embodied in the concept of an indicator species. A useful indicator species is one whose abundance and distribution or sometimes simply its presence or absence in time and space are limited by physical parameters related to climate. The niche variables that, to the evolutionary ecologist, were agents of natural selection among individuals to the paleoclimatologist become the critical...
Obliquity or Tilt
Today the earth's axis of rotation is tilted about 23.5 relative to the ecliptic plane and is gradually declining at a rate of about 0.5 yr. The inclination of the axis of Venus is, by contrast, tilted only 3 . When earth is tilted toward the sun, there is summer in one hemisphere and winter in the other. Earth's tilt has varied over long time scales between 22 to 25 , owing to planetary effects on the position of the ecliptic in space. One complete cycle of obliquity takes about 41 ka. The...
Astronomical Tuning
Tuning'' represents a novel and somewhat controversial method to date and correlate paleoclimatic events related to the orbital theory of climate change. This theory holds that gravitational influences on earth's orbital eccentricity, tilt, and precession affect seasonal and geographical distribution of solar radiation and global climate. Geologists have for more than a century tried to establish whether the timing of orbital cycles as determined by celestial mechanics e.g., Berger et al. 1984,...
Principles of Paleoclimatology 1
Copyright 1999 Columbia University Press All rights reserved Library of Congress Cataloging-in-Publication Data Cronin, Thomas M. Principles of paleoclimatology Thomas M. Cronin. p. cm. Perspectives in paleobiology and earth history series Includes bibliographical references and index. ISBN 0-231-10954-7 cl alk. paper . ISBN 0-231-10955-5 pbk. alk. paper 1. Paleoclimatology. I. Title. II. Series. QC884.C74 1999 Casebound editions of Columbia University Press books are printed on permanent and...
Communities and Ecosystems
Communities of plants and animals are defined as groups of species that have evolved to coexist and interact in a variety of ways. Communities represent a higher level of biotic integration than populations and species. The concept of community in ecology incorporates the biological elements i.e., species but usually excludes the physical parameters that influence individuals and populations living in the community. A community is therefore not solely defined by the spatial dimensions of the...
The Evolution Of Glacialage Climatology
With the basic concepts of faunal and isotopic proxy methods in hand, I wish to elaborate on the development and use of new and innovative proxy methods, such as the emu geochemistry introduced earlier in this chapter, to reconstruct glacial-age climates. New proxy development and application does not occur in a vacuum. Paleoclima-tologists operate in a hypothetico-deductive mode, so that as new hypotheses develop to explain past climate changes, new tools are needed to test the hypotheses. A...
Stable Isotopes
Stable isotope ratios of oxygen 18O 16O , carbon 13C 12C , hydrogen deuterium, 2H 1H, in ice cores , and to a lesser extent nitrogen 15N 14N probably comprise the single most important family of paleoclimate tools used to reconstruct past climates. A proper treatment of stable isotope paleoclimatology would require volumes the following brief section on the terminology of stable isotopes gives the basic tenets of the stable isotope method and a foundation for many applications described in...