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 4. Dating Methods II Front Cover Photograph xiii Paleomagnetism 103 Foreword xv The Earth’s Magnetic Field 104 Preface to the Third Edition xix Magnetization of Rocks and Sediments 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 Amino Acid Dating 113 Levels of Paleoclimatic Analysis 9 Obsidian Hydration Dating 124 Modeling in Paleoclimatic Research 10 Tephrochronology 125 Biological Dating Methods 129 2. Climate and Climatic Variation Lichenometry 129 Dendrochronology 135 The Nature of Climate and Climatic Variation 13 5. Ice Cores The Climate System 16 Feedback Mechanisms 24 Introduction 137 Energy Balance of the Earth and Its Stable Isotope Analysis 141 Atmosphere 27 Stable Isotopes in Water: Measurement and Timescales of Climatic Variation 33 Standardization 143 Variations of the Earth’s Orbital Parameters 36 Oxygen-18 Concentration in Atmospheric Solar Forcing 46 Precipitation 144 Volcanic Forcing 50 Factors Affecting the Stable Isotope Record in Ice Cores 145 3. Dating Methods I Deuterium Excess 151 Dating Ice Cores 154 Introduction and Overview 55 Radioisotopic Methods 155 Radioisotopic Methods 57 Seasonal Variations and Episodic Events 155 Radiocarbon Dating 59 Theoretical Models 165 40 40 Potassium-Argon Dating ( K/ Ar) 83 Chronostratigraphic Correlations 167 Uranium-Series Dating 85 Paleoclimatic Reconstruction from Ice Cores 167 Luminescence Dating: Principles and Ice-Core Records from Greenland 167 Applications 91 Ice-Core Records from Antarctica 175 Surface Exposure Dating 98 Past Atmospheric Composition from Fission-Track Dating 100 Polar Ice Cores 180 vii viii CONTENTS Greenhouse Gas Records in Ice Cores 184 Speleothems and Glacial Terminations 299 Ice-Core Records from Low Latitudes 189 Millennial to Centennial Scale Changes 302 Late Glacial and Holocene Records 304 6. Marine Sediments Stalagmite Records of the Last Two Millennia 310 Introduction 196 Paleoclimatic Information from Periods of Speleothem Paleoclimatic Information from Biological Material Growth 311 in Ocean Cores 197 Speleothems as Indicators of Sea-Level Oxygen Isotope Studies of Calcareous Marine Variations 315 Fauna 199 Isotopic Composition of the Oceans 201 9. Lake Sediments Oxygen Isotope Stratigraphy 211 Orbital Tuning 215 Sedimentology and Inorganic Geochemistry 320 Orbital Forcing: Evidence from the Marine Varves 323 Record 220 Pollen, Macrofossils, and Phytoliths 324 Sea Level Changes and d18O 222 Ostracods 327 Paleotemperatures from Relative Abundance Diatoms 327 Studies 225 Stable Isotopes 330 Paleotemperature Reconstruction from Sediment 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 Sea Ice 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 Mountain Glacier Fluctuations 358 Thermohaline Circulation of the Oceans 248 Evidence of Glacier Fluctuations 359 Tracers in the Ocean 252 The Record of Glacier Front Positions 360 Changes in Atmospheric Carbon 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. Loess 11. Insects and Other Biological Evidence from Continental Regions Chronology of Loess-Paleosol Sequences 284 Paleoclimatic Significance of Loess-Paleosol Introduction 377 Sequences 287 Insects 377 Paleoclimatic Reconstructions Based on Fossil Coleoptera 379 8. Speleothems Paleoclimatic Reconstruction Based on Aquatic Insects 384 Isotopic Variations in Speleothems 295 Former Vegetation Distribution from Plant Tropical and Subtropical Paleoclimate Variability Macrofossils 388 from Speleothems 296 Arctic Tree 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 Temperatures over the Peat 400 Northern Hemisphere 480 Drought Reconstruction 481 12. Pollen Reconstruction of Atmospheric Circulation Modes 487 Introduction 405 Wildfires and Dendroclimatology 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 Rain 410 Sources of Fossil Pollen 410 14. Corals Preparation of the Samples 411 Pollen Analysis of a Site: The Pollen Coral 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 Maps 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 Europe 434 Historical Weather 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 Africa 445 Regional Studies Based on Historical Records 538 Northeastern Siberia 449 East Asia 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 paleoclimatology is continually ical, chemical, and biological systems that becoming more interdisciplinary as practi- interact on a spectrum of time 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 proxy 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 resource the Earth System may change in the future for earth scientists 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