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Home , Climate, Climate system, Climatology, Dendroclimatology, Glacier, Ice core

PALEOCLIMATOLOGY Reconstructing of the

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 4. Dating Methods II Front Cover Photograph xiii 103 Foreword xv The ’s Magnetic 104 Preface to the Third Edition xix Magnetization of Rocks and 105 The Paleomagnetic Timescale 107 Geomagnetic Excursions 108 1. Paleoclimatic Reconstruction Relative Paleointensity Variations 110 Secular Variations of the Earth’s Magnetic Field 111 Introduction 1 Dating Methods Involving Chemical Changes 111 Sources of Paleoclimatic Information 4 113 Levels of Paleoclimatic Analysis 9 Obsidian Hydration Dating 124 Modeling in Paleoclimatic Research 10 125 Biological Dating Methods 129 2. and Climatic Variation 129 135 The of Climate and Climatic Variation 13 5. Cores The 16 Feedback Mechanisms 24 Introduction 137 Balance of the Earth and Its Stable Analysis 141 27 Stable in : Measurement and Timescales of Climatic Variation 33 Standardization 143 Variations of the Earth’s Orbital Parameters 36 -18 Concentration in Atmospheric Solar Forcing 46 144 Volcanic Forcing 50 Factors Affecting the Stable Isotope Record in Ice Cores 145 3. Dating Methods I Excess 151 Dating Ice Cores 154 Introduction and Overview 55 Radioisotopic Methods 155 Radioisotopic Methods 57 Seasonal Variations and Episodic Events 155 59 Theoretical Models 165 40 40 Potassium- Dating ( K/ Ar) 83 Chronostratigraphic Correlations 167 Uranium-Series Dating 85 Paleoclimatic Reconstruction from Ice Cores 167 : Principles and Ice-Core Records from 167 Applications 91 Ice-Core Records from 175 Surface Exposure Dating 98 Atmospheric Composition from Fission-Track Dating 100 Polar Ice Cores 180

vii viii CONTENTS

Greenhouse Gas Records in Ice Cores 184 and Glacial Terminations 299 Ice-Core Records from Low 189 Millennial to Centennial Scale Changes 302 Late Glacial and Records 304 6. Marine Sediments Stalagmite Records of the Last Two Millennia 310 Introduction 196 Paleoclimatic Information from Periods of Paleoclimatic Information from Biological Material Growth 311 in Cores 197 Speleothems as Indicators of -Level Oxygen Isotope Studies of Calcareous Marine Variations 315 199 Isotopic Composition of the 201 9. Sediments Oxygen Isotope 211 Orbital Tuning 215 and Inorganic 320 : Evidence from the Marine Varves 323 Record 220 , Macrofossils, and 324 Changes and d18O 222 Ostracods 327 Paleotemperatures from Relative Abundance Diatoms 327 Studies 225 Stable Isotopes 330 Paleotemperature Reconstruction from Organic Biomarkers 338 Geochemistry 228 Paleotemperatures from Alkenones 228 10. Nonmarine Geologic Evidence Paleotemperatures from TEX86 and Long-Chain Diols 231 Introduction 345 Periglacial Features 346 IP25 and Related Proxies 234 Paleotemperatures from Mg/Ca Ratios 238 Snowlines and Glaciation Thresholds 351 Oceanographic Conditions at the Last Glacial The Climatic and Paleoclimatic Interpretation of Maximum (LGM) 239 Snowlines and ELAs 352 The Age of Former Snowlines 356 Paleoclimatic Information from Inorganic Material in Marine Sediments 244 Fluctuations 358 of the Oceans 248 Evidence of Glacier Fluctuations 359 Tracers in the Ocean 252 The Record of Glacier Front Positions 360 Changes in Atmospheric Dioxide: The Role of Lake-level Fluctuations 362 the Oceans 258 Hydrologic Balance Models 366 Abrupt Climate Changes 263 Hydrologic-Energy Balance Models 370 Heinrich Events 267 Regional Patterns of Lake-Level Fluctuations 371

7. 11. Insects and Other Biological Evidence from Continental of Loess- Sequences 284 Paleoclimatic Significance of Loess-Paleosol Introduction 377 Sequences 287 Insects 377 Paleoclimatic Reconstructions Based on Coleoptera 379 8. Speleothems Paleoclimatic Reconstruction Based on Aquatic Insects 384 Isotopic Variations in Speleothems 295 Former Vegetation Distribution from Tropical and Subtropical Paleoclimate Variability Macrofossils 388 from Speleothems 296 Line Fluctuations 389 CONTENTS ix

Alpine Tree Line Fluctuations 392 Verification of Climatic Reconstructions 476 Lower Tree Line Fluctuations and Rodent Dendroclimatic Reconstructions 480 Middens 395 Reconstructions of over the Peat 400 480 Reconstruction 481 12. Pollen Reconstruction of Modes 487 Introduction 405 and 490 The Basis of Pollen Analysis 406 Isotopic Dendroclimatology 493 Pollen Grain Characteristics 408 d18O and d2H 493 Pollen Productivity and Dispersal: The Pollen d13C 495 410 Sources of Fossil Pollen 410 14. Preparation of the Samples 411 Pollen Analysis of a Site: The Pollen Records of Past Climate 499 Diagram 411 Paleoclimate from Coral Growth Rates 506 Zonation of the Pollen Diagram 414 Luminescence in Corals 506 Pollen Rain as a Representation of Vegetation d18O in Corals 507 Composition and Climate 414 d13C in Corals 510 of Modern Pollen Data 416 D14C in Corals 510 Mapping Vegetation Change: Isopolls and Trace Elements in Corals 511 Isochrones 418 Fossil Coral Records 512 How Rapidly Does Vegetation Respond to Changes in Climate? 422 Quantitative Paleoclimatic Reconstructions Based on 15. Historical Documents Pollen Analysis 425 Paleoclimatic Reconstruction from Long Quaternary Introduction 517 Pollen Records 434 Historical Records and Their Interpretation 519 434 Historical Observations 524 Sabana de Bogota´, Colombia 438 Historical Records of Weather-Dependent Natural Central American Lowlands 441 Phenomena 526 Amazonia 443 Phenological and Biological Records 534 Equatorial and Sub-Saharan 445 Regional Studies Based on Historical Records 538 Northeastern 449 East 540 Europe 544 13. Tree Rings Records of Climate Forcing Factors 545 Climate Paradigms for the Last Millennium 548 Introduction 453 Fundamentals of Dendroclimatology 454 Appendix A 553 Sample Selection 456 Cross Dating 458 Appendix B 557 Standardization of Ring-Width Data 463 References 559 Divergence 469 Calibration of Tree-Ring Data 470 Index 667 Foreword

Earth is a constantly changing dynamic considered for robust interpretations. The entity, composed of multiple complex phys- field of is continually ical, chemical, and biological systems that becoming more interdisciplinary as practi- interact on a spectrum of and spatial tioners strive to understand and incorporate scales. To comprehend the Earth System as an ever increasing number of highly special- a whole, we must understand the nature of ized climate and environmental these complex subsystems, both now and indicators. in the past, and identify the important link- In concert with these developments in the ages among them. Earth is now experiencing field, the first two editions of Professor many changes, some large and more rapid Raymond Bradley’s book, Paleoclimatology, than others. To attempt predictions of how have proven to be an indispensable the Earth System may change in the future for earth at all stages of their careers, requires an assessment of the conditions that from undergraduate students to seasoned preceded the present, a perspective that can professionals. The second edition is not only only be gained from the records of past cli- required reading in my graduate paleoclima- mate. Studies of the past also reveal just tology course but it also occupies a prominent how quickly some components of the Earth and easily accessible place in my research Systems have responded to specific external library. For almost the last three decades, (e.g., solar) and internal (e.g., atmospheric Paleoclimatology has provided readers with a chemistry) forcing factors. Knowledge of broad perspective on the development and these changes and understanding their key interpretation of a wide variety of climate drivers are critical to efforts to anticipate records, including explanations of both estab- and plan for future environmental changes. lished and state-of-the-art techniques used to We are very fortunate that today we have reconstruct Quaternary climates. The text, a rich body of knowledge and numerous which is accompanied by numerous illustra- diverse natural systems that record many tions, is sufficiently concise and instructive types of climatic and environmental infor- for established researchers and educators mation across a spectrum of temporal scales. but is also easy for scientific novices to Additionally, we now have rich array of comprehend. technologies that allow us to tap information The third edition, Paleoclimatology: Recon- at ever smaller concentrations and from both structing Climates of the Quaternary, has been common and rare archives. However, to extensively updated, but maintains its mis- reconstruct the nature, magnitude, and tim- sion of broad appeal across the various sub- ing of these changes, paleoclimatologists disciplines of . One can quickly must also understand the biological and appreciate the comprehensive nature of this physical processes that govern the formation book by browsing through the bibliography, of these diverse proxy records. As impor- which contains almost 2500 references. tantly, the strengths and limitations of each Speaking as a long-practicing paleoclimatol- proxy indicator must be known and ogist, I often become immersed in the details

xv xvi FOREWORD of my specialty area and lose track of the calibration techniques are used. Abundant extremely important work of colleagues in examples of records derived from these other fields that are equally essential to archives are provided from around understand the larger scale processes that the . constitute our climate system. As with other In addition to revising and updating the scientific fields, climatologists cannot use a chapters in the second edition, he expands “silver bullet” approach when working on the discussions of proxy records that were and presenting their research. They must previously grouped together. Specifically, understand and reference literature and data discussions on loess, speleothems, and lake from other areas. The beauty of Professor sediments, which were previously grouped Bradley’s book is that it compiles and orga- in a chapter called “Non-Marine Geological nizes masses of both interconnected and dis- Evidence,” now appear in separate chapters parate information (silver buckshot) in a in the third edition. holistic way that helps us understand the In the chapter on ice cores, which is my complexities and interdependencies in the specialty, Professor Bradley provides a climate system. coherent and understandable primer on sta- This third edition is one of the best written ble isotopes in precipitation that includes reference books in the field, using prose that information on their calibration for paleo- is easy to understand and explanations of reconstruction. The discussion difficult concepts that are presented as only of the records is more comprehensive than an experienced lecturer and teacher of Pro- many other treatments of the subject, as it fessor Bradley’s caliber can do. The text is includes records from both high and low lat- logically arranged, beginning with an overall itudes and deals with a multitude of review of the reconstruction of paleoclimate parameters. The longest chapter is devoted records and a discussion of the climate sys- to records. This is appropri- tem and forcing mechanisms. This is fol- ate given the huge amount of diverse litera- lowed by a considerably detailed overview ture. Other chapters cover tree rings, corals, of dating techniques, which is critical since insects and biological evidence, and pollen. the key to understanding any climatic or The final chapter covers the information environmental record lies in robust time con- available from historical documentation. trol. Professor Bradley provides an excellent I first met Professor Raymond Bradley in up-to-date overview of the strengths and 1983 at a NATO/NSF Workshop on Abrupt weaknesses of the various techniques, rang- Climatic Change in Biviers, . For ing from classical and widely used methods 30 , our paths have crossed many such as radiocarbon dating to more special- at professional meetings, seminars, and ized and less “publicly” familiar methods workshops. I have also had the pleasure of such as luminescence, amino-acid, licheno- working with him on manuscripts and book metry, and dendrochronology. projects. His interests include , The majority of the book provides over- paleoclimatology, , and the views of the various archives used for cli- Arctic environment. Professor Bradley is a matic and environmental reconstruction. member of the Real Climate blog and has For each of the archives, the author summa- made sustained and significant contribu- rizes the various parameters recorded by and tions to discussions on global warming. He extracted from each type of proxy, as well as has a true passion for the paleoclimate com- how the time control is established, and what munity and has worked diligently and FOREWORD xvii effectively on programs (such as PAGES) warming since the mid-20th century,” we which strive to bring together the paleocli- urgently need to understand the natural fac- mate and the modeling communities to forge tors that forced climate variability in the past. a more robust understanding of global cli- This body of knowledge provides the critical mate variability in the present, past, and baseline and corpus of knowledge that will future. underpin more robust predictions of the We are just beginning to realize how cli- future impact of activities. Professor mate change has emerged as a powerful Raymond Bradley has provided the field of causal agent in the evolution of civilizations, paleoclimatology an excellent spatial and including those that exist today. One of the temporal summary of where we are along major challenges to predicting future climate the continuum to a deeper understanding is to determine the specific causes of both of Earth’s past and present climate. past and present changes. In light of the gen- eral conclusion of the latest Intergovernmen- Lonnie G. Thompson tal Panel on that “it is Byrd Polar Research Center extremely likely that human interference The Ohio State University has been the dominant cause of the observed Columbus Preface to the Third Edition

The first edition of Quaternary Paleoclima- volume of specialists might present. I hope that tology was published in 1985 when the field those who turn to their particular areas of of paleoclimatology was still in its infancy expertise will do so with the overall objectives and there was a reasonable chance that you of the book in mind; it was simply not possible could read most of the relevant papers. The to provide a comprehensive review of every field grew rapidly over the next decade, subfield and still try to maintain an up-to-date and so I wrote a much more extensive and overview of the rest of paleoclimatology. The updated version, Paleoclimatology: Recon- final product is thus a compromise between structing Climates of the Quaternary, which completeness, expediency, and (eventually) was published in 1999. Over the last decade, exhaustion. Nevertheless, I hope I have done the field has grown even faster so that it is justice to most topics, and that the new refer- now almost impossible to keep track of every ences I have included will enable interested of the subject. As just one example, readers to quickly access the important litera- more than 3500 papers with the keywords ture. There is no substitute for reading the orig- “ice cores” have been published since inal scientific papers. 1999—a number greater than the entire field My goal in writing this edition was to pro- of paleoclimatology in the early 1980s. Inev- vide a comprehensive overview of the field itably, this means that research is becoming of paleoclimatology and the record of cli- ever more specialized so that it is increas- matic changes during the Quaternary. New ingly difficult to gain a broad perspective records are being obtained all the time, and on the field, and to appreciate the pros and new analytical techniques are being devel- cons of particular proxies being used in oped and applied, giving us new and excit- paleoclimatic reconstruction. Consequently, ing insights into how climates have I think a book like this can serve an even changed over time. I have tried to capture more useful purpose than the first and sec- some of these developments in the book. ond editions, for all those interested in All sections have been comprehensively understanding past climates. My goal from revised and updated, but in particular, the the beginning has been to enable nonspecialists book includes new material on dating in anyone subfield ofpaleoclimatology to learn (including updates on calibration of the enough of the basics in other subfields to allow radiocarbon timescale and surface exposure them to read and appreciate the literature they dating) extensively revised chapters on ice might not otherwise understand. Hopefully, cores and marine sediments and ocean circu- this will promote better communication of lation in the past, new chapters on loess, spe- ideas within the community of paleoclimatolo- leothems, lake sediments, and corals and gists and beyond. As I noted in the Preface of greatly revised chapters on insects, pollen thepreviousedition,Ibelievethereareadvan- analysis, tree rings, and historical records. tages in having one lens through which this To keep the task somewhat manageable, I rapidly evolving field is viewed, rather than decided not to include a separate chapter a spectrum of perspectives that an edited on paleoclimate models, but to keep the

xix xx PREFACE TO THE THIRD EDITION focus on proxies used in paleoclimatic this book, and so I hope that those who read reconstruction. Over 1200 new references it will find it equally informative in their own have been added, almost all of them pub- studies. lished within the last decade, and there are 200 new figures, all with detailed explana- Ray Bradley tory captions. I have learned a lot in writing Leverett, MA, November 2013