PALEOCLIMATOLOGY
Reconstructing Climates of the
Quaternary
THIRD EDITION
RAYMOND S. BRADLEY
University of Massachusetts, Amherst, Massachusetts
AMSTERDAM • BOSTON • HEIDELBERG • LONDON
NEW YORK • OXFORD • PARIS • SAN DIEGO
SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
Academic Press is an imprint of Elsevier
Contents
Acknowledgments xi
Front Cover Photograph xiii
Foreword xv
Preface to the Third Edition xix
4. Dating Methods II
Paleomagnetism 103
The Earth’s Magnetic Field 104
Magnetization of Rocks and Sediments 105
The Paleomagnetic Timescale 107
Geomagnetic Excursions 108
Relative Paleointensity Variations 110
Secular Variations of the Earth’s Magnetic Field 111
Dating Methods Involving Chemical Changes 111
Amino Acid Dating 113
Obsidian Hydration Dating 124
Tephrochronology 125
Biological Dating Methods 129
Lichenometry 129
Dendrochronology 135
1. Paleoclimatic Reconstruction
Introduction 1
Sources of Paleoclimatic Information 4
Levels of Paleoclimatic Analysis 9
Modeling in Paleoclimatic Research 10
2. Climate and Climatic Variation
The Nature of Climate and Climatic
Variation 13
The Climate System 16
Feedback Mechanisms 24
Energy Balance of the Earth and Its
Atmosphere 27
Timescales of Climatic Variation 33
Variations of the Earth’s Orbital Parameters
Solar Forcing 46
Volcanic Forcing 50
5. Ice Cores
Introduction 137
Stable Isotope Analysis 141
Stable Isotopes in Water: Measurement and
Standardization 143
Oxygen-18 Concentration in Atmospheric
Precipitation 144
Factors Affecting the Stable Isotope Record
in Ice Cores 145
Deuterium Excess 151
Dating Ice Cores 154
Radioisotopic Methods 155
Seasonal Variations and Episodic Events 155
Theoretical Models 165
Chronostratigraphic Correlations 167
Paleoclimatic Reconstruction from Ice Cores 167
Ice-Core Records from Greenland 167
Ice-Core Records from Antarctica 175
Past Atmospheric Composition from
Polar Ice Cores 180
36
3. Dating Methods I
Introduction and Overview 55
Radioisotopic Methods 57
Radiocarbon Dating 59
Potassium-Argon Dating (40K/40Ar) 83
Uranium-Series Dating 85
Luminescence Dating: Principles and
Applications 91
Surface Exposure Dating 98
Fission-Track Dating 100
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CONTENTS
Greenhouse Gas Records in Ice Cores 184
Ice-Core Records from Low Latitudes 189
6. Marine Sediments
Introduction 196
Paleoclimatic Information from Biological Material
in Ocean Cores 197
Oxygen Isotope Studies of Calcareous Marine
Fauna 199
Isotopic Composition of the Oceans 201
Oxygen Isotope Stratigraphy 211
Orbital Tuning 215
Orbital Forcing: Evidence from the Marine
Record 220
Sea Level Changes and d18O 222
Paleotemperatures from Relative Abundance
Studies 225
Paleotemperature Reconstruction from Sediment
Geochemistry 228
Paleotemperatures from Alkenones 228
Paleotemperatures from TEX86 and Long-Chain
Diols 231
IP25 and Related Sea Ice Proxies 234
Paleotemperatures from Mg/Ca Ratios 238
Oceanographic Conditions at the Last Glacial
Maximum (LGM) 239
Paleoclimatic Information from Inorganic Material in
Marine Sediments 244
Thermohaline Circulation of the Oceans 248
Tracers in the Ocean 252
Changes in Atmospheric Carbon Dioxide: The Role of
the Oceans 258
Abrupt Climate Changes 263
Heinrich Events 267
7. Loess
Chronology of Loess-Paleosol Sequences 284
Paleoclimatic Significance of Loess-Paleosol
Sequences 287
8. Speleothems
Isotopic Variations in Speleothems 295
Tropical and Subtropical Paleoclimate Variability
from Speleothems 296
Speleothems and Glacial Terminations 299
Millennial to Centennial Scale Changes 302
Late Glacial and Holocene Records 304
Stalagmite Records of the Last Two
Millennia 310
Paleoclimatic Information from Periods of Speleothem
Growth 311
Speleothems as Indicators of Sea-Level
Variations 315
9. Lake Sediments
Sedimentology and Inorganic Geochemistry
Varves 323
Pollen, Macrofossils, and Phytoliths 324
Ostracods 327
Diatoms 327
Stable Isotopes 330
Organic Biomarkers 338
320
10. Nonmarine Geologic Evidence
Introduction 345
Periglacial Features 346
Snowlines and Glaciation Thresholds 351
The Climatic and Paleoclimatic Interpretation of
Snowlines and ELAs 352
The Age of Former Snowlines 356
Mountain Glacier Fluctuations 358
Evidence of Glacier Fluctuations 359
The Record of Glacier Front Positions 360
Lake-level Fluctuations 362
Hydrologic Balance Models 366
Hydrologic-Energy Balance Models 370
Regional Patterns of Lake-Level Fluctuations 371
11. Insects and Other Biological Evidence
from Continental Regions
Introduction 377
Insects 377
Paleoclimatic Reconstructions Based on Fossil
Coleoptera 379
Paleoclimatic Reconstruction Based on Aquatic
Insects 384
Former Vegetation Distribution from Plant
Macrofossils 388
Arctic Tree Line Fluctuations 389
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CONTENTS
Alpine Tree Line Fluctuations 392
Lower Tree Line Fluctuations and Rodent
Middens 395
Peat 400
12. Pollen
Introduction 405
The Basis of Pollen Analysis 406
Pollen Grain Characteristics 408
Pollen Productivity and Dispersal: The Pollen
Rain 410
Sources of Fossil Pollen 410
Preparation of the Samples 411
Pollen Analysis of a Site: The Pollen
Diagram 411
Zonation of the Pollen Diagram 414
Pollen Rain as a Representation of Vegetation
Composition and Climate 414
Maps of Modern Pollen Data 416
Mapping Vegetation Change: Isopolls and
Isochrones 418
How Rapidly Does Vegetation Respond to Changes
in Climate? 422
Quantitative Paleoclimatic Reconstructions Based on
Pollen Analysis 425
Paleoclimatic Reconstruction from Long Quaternary
Pollen Records 434
Europe 434
Sabana de Bogotá, Colombia 438
Central American Lowlands 441
Amazonia 443
Equatorial and Sub-Saharan Africa 445
Northeastern Siberia 449
13. Tree Rings
Introduction 453
Fundamentals of Dendroclimatology 454
Sample Selection 456
Cross Dating 458
Standardization of Ring-Width Data 463
Divergence 469
Calibration of Tree-Ring Data 470
Verification of Climatic Reconstructions 476
Dendroclimatic Reconstructions 480
Reconstructions of Temperatures over the
Northern Hemisphere 480
Drought Reconstruction 481
Reconstruction of Atmospheric Circulation
Modes 487
Wildfires and Dendroclimatology 490
Isotopic Dendroclimatology 493
d18O and d2H 493
d13C 495
14. Corals
Coral Records of Past Climate 499
Paleoclimate from Coral Growth Rates
Luminescence in Corals 506
d18O in Corals 507
d13C in Corals 510
D14C in Corals 510
Trace Elements in Corals 511
Fossil Coral Records 512
506
15. Historical Documents
Introduction 517
Historical Records and Their Interpretation 519
Historical Weather Observations 524
Historical Records of Weather-Dependent Natural
Phenomena 526
Phenological and Biological Records 534
Regional Studies Based on Historical Records 538
East Asia 540
Europe 544
Records of Climate Forcing Factors 545
Climate Paradigms for the Last Millennium 548
Appendix A 553
Appendix B 557
References 559
Index 667
Foreword
considered for robust interpretations. The
field of paleoclimatology is continually
becoming more interdisciplinary as practitioners strive to understand and incorporate
an ever increasing number of highly specialized proxy climate and environmental
indicators.
In concert with these developments in the
field, the first two editions of Professor
Raymond Bradley’s book, Paleoclimatology,
have proven to be an indispensable resource
for earth scientists at all stages of their careers,
from undergraduate students to seasoned
professionals. The second edition is not only
required reading in my graduate paleoclimatology course but it also occupies a prominent
and easily accessible place in my research
library. For almost the last three decades,
Paleoclimatology has provided readers with a
broad perspective on the development and
interpretation of a wide variety of climate
records, including explanations of both established and state-of-the-art techniques used to
reconstruct Quaternary climates. The text,
which is accompanied by numerous illustrations, is sufficiently concise and instructive
for established researchers and educators
but is also easy for scientific novices to
comprehend.
The third edition, Paleoclimatology: Reconstructing Climates of the Quaternary, has been
extensively updated, but maintains its mission of broad appeal across the various subdisciplines of earth science. One can quickly
appreciate the comprehensive nature of this
book by browsing through the bibliography,
which contains almost 2500 references.
Speaking as a long-practicing paleoclimatologist, I often become immersed in the details
Earth is a constantly changing dynamic
entity, composed of multiple complex physical, chemical, and biological systems that
interact on a spectrum of time and spatial
scales. To comprehend the Earth System as
a whole, we must understand the nature of
these complex subsystems, both now and
in the past, and identify the important linkages among them. Earth is now experiencing
many changes, some large and more rapid
than others. To attempt predictions of how
the Earth System may change in the future
requires an assessment of the conditions that
preceded the present, a perspective that can
only be gained from the records of past climate. Studies of the past also reveal just
how quickly some components of the Earth
Systems have responded to specific external
(e.g., solar) and internal (e.g., atmospheric
chemistry) forcing factors. Knowledge of
these changes and understanding their key
drivers are critical to efforts to anticipate
and plan for future environmental changes.
We are very fortunate that today we have
a rich body of knowledge and numerous
diverse natural systems that record many
types of climatic and environmental information across a spectrum of temporal scales.
Additionally, we now have rich array of
technologies that allow us to tap information
at ever smaller concentrations and from both
common and rare archives. However, to
reconstruct the nature, magnitude, and timing of these changes, paleoclimatologists
must also understand the biological and
physical processes that govern the formation
of these diverse proxy records. As importantly, the strengths and limitations of each
proxy indicator must be known and
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FOREWORD
of my specialty area and lose track of the
extremely important work of colleagues in
other fields that are equally essential to
understand the larger scale processes that
constitute our climate system. As with other
scientific fields, climatologists cannot use a
“silver bullet” approach when working on
and presenting their research. They must
understand and reference literature and data
from other areas. The beauty of Professor
Bradley’s book is that it compiles and organizes masses of both interconnected and disparate information (silver buckshot) in a
holistic way that helps us understand the
complexities and interdependencies in the
climate system.
This third edition is one of the best written
reference books in the field, using prose that
is easy to understand and explanations of
difficult concepts that are presented as only
an experienced lecturer and teacher of Professor Bradley’s caliber can do. The text is
logically arranged, beginning with an overall
review of the reconstruction of paleoclimate
records and a discussion of the climate system and forcing mechanisms. This is followed by a considerably detailed overview
of dating techniques, which is critical since
the key to understanding any climatic or
environmental record lies in robust time control. Professor Bradley provides an excellent
up-to-date overview of the strengths and
weaknesses of the various techniques, ranging from classical and widely used methods
such as radiocarbon dating to more specialized and less “publicly” familiar methods
such as luminescence, amino-acid, lichenometry, and dendrochronology.
The majority of the book provides overviews of the various archives used for climatic and environmental reconstruction.
For each of the archives, the author summarizes the various parameters recorded by and
extracted from each type of proxy, as well as
how the time control is established, and what
calibration techniques are used. Abundant
examples of records derived from these
archives are provided from around
the world.
In addition to revising and updating the
chapters in the second edition, he expands
the discussions of proxy records that were
previously grouped together. Specifically,
discussions on loess, speleothems, and lake
sediments, which were previously grouped
in a chapter called “Non-Marine Geological
Evidence,” now appear in separate chapters
in the third edition.
In the chapter on ice cores, which is my
specialty, Professor Bradley provides a
coherent and understandable primer on stable isotopes in precipitation that includes
information on their calibration for paleotemperature reconstruction. The discussion
of the records is more comprehensive than
many other treatments of the subject, as it
includes records from both high and low latitudes and deals with a multitude of ice core
parameters. The longest chapter is devoted
to marine sediment records. This is appropriate given the huge amount of diverse literature. Other chapters cover tree rings, corals,
insects and biological evidence, and pollen.
The final chapter covers the information
available from historical documentation.
I first met Professor Raymond Bradley in
1983 at a NATO/NSF Workshop on Abrupt
Climatic Change in Biviers, France. For
30 years, our paths have crossed many times
at professional meetings, seminars, and
workshops. I have also had the pleasure of
working with him on manuscripts and book
projects. His interests include climatology,
paleoclimatology, global change, and the
Arctic environment. Professor Bradley is a
member of the Real Climate blog and has
made sustained and significant contributions to discussions on global warming. He
has a true passion for the paleoclimate community and has worked diligently and
FOREWORD
effectively on programs (such as PAGES)
which strive to bring together the paleoclimate and the modeling communities to forge
a more robust understanding of global climate variability in the present, past, and
future.
We are just beginning to realize how climate change has emerged as a powerful
causal agent in the evolution of civilizations,
including those that exist today. One of the
major challenges to predicting future climate
is to determine the specific causes of both
past and present changes. In light of the general conclusion of the latest Intergovernmental Panel on Climate Change that “it is
extremely likely that human interference
has been the dominant cause of the observed
xvii
warming since the mid-20th century,” we
urgently need to understand the natural factors that forced climate variability in the past.
This body of knowledge provides the critical
baseline and corpus of knowledge that will
underpin more robust predictions of the
future impact of human activities. Professor
Raymond Bradley has provided the field of
paleoclimatology an excellent spatial and
temporal summary of where we are along
the continuum to a deeper understanding
of Earth’s past and present climate.
Lonnie G. Thompson
Byrd Polar Research Center
The Ohio State University
Columbus
Preface to the Third Edition
The first edition of Quaternary Paleoclimatology was published in 1985 when the field
of paleoclimatology was still in its infancy
and there was a reasonable chance that you
could read most of the relevant papers. The
field grew rapidly over the next decade,
and so I wrote a much more extensive and
updated version, Paleoclimatology: Reconstructing Climates of the Quaternary, which
was published in 1999. Over the last decade,
the field has grown even faster so that it is
now almost impossible to keep track of every
aspect of the subject. As just one example,
more than 3500 papers with the keywords
“ice cores” have been published since
1999—a number greater than the entire field
of paleoclimatology in the early 1980s. Inevitably, this means that research is becoming
ever more specialized so that it is increasingly difficult to gain a broad perspective
on the field, and to appreciate the pros and
cons of particular proxies being used in
paleoclimatic reconstruction. Consequently,
I think a book like this can serve an even
more useful purpose than the first and second editions, for all those interested in
understanding past climates. My goal from
the beginning has been to enable nonspecialists
in any one subfield of paleoclimatology to learn
enough of the basics in other subfields to allow
them to read and appreciate the literature they
might not otherwise understand. Hopefully,
this will promote better communication of
ideas within the community of paleoclimatologists and beyond. As I noted in the Preface of
the previous edition, I believe there are advantages in having one lens through which this
rapidly evolving field is viewed, rather than
a spectrum of perspectives that an edited
volume of specialists might present. I hope that
those who turn to their particular areas of
expertise will do so with the overall objectives
of the book in mind; it was simply not possible
to provide a comprehensive review of every
subfield and still try to maintain an up-to-date
overview of the rest of paleoclimatology. The
final product is thus a compromise between
completeness, expediency, and (eventually)
exhaustion. Nevertheless, I hope I have done
justice to most topics, and that the new references I have included will enable interested
readers to quickly access the important literature. There is no substitute for reading the original scientific papers.
My goal in writing this edition was to provide a comprehensive overview of the field
of paleoclimatology and the record of climatic changes during the Quaternary. New
records are being obtained all the time, and
new analytical techniques are being developed and applied, giving us new and exciting insights into how climates have
changed over time. I have tried to capture
some of these developments in the book.
All sections have been comprehensively
revised and updated, but in particular, the
book includes new material on dating
(including updates on calibration of the
radiocarbon timescale and surface exposure
dating) extensively revised chapters on ice
cores and marine sediments and ocean circulation in the past, new chapters on loess, speleothems, lake sediments, and corals and
greatly revised chapters on insects, pollen
analysis, tree rings, and historical records.
To keep the task somewhat manageable, I
decided not to include a separate chapter
on paleoclimate models, but to keep the
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PREFACE TO THE THIRD EDITION
focus on proxies used in paleoclimatic
reconstruction. Over 1200 new references
have been added, almost all of them published within the last decade, and there are
200 new figures, all with detailed explanatory captions. I have learned a lot in writing
this book, and so I hope that those who read
it will find it equally informative in their own
studies.
Ray Bradley
Leverett, MA, November 2013