Paleoclimatology

Life on our planet depends upon having a climate that changes within narrow limits - not too hot for the oceans to boil away nor too cold for the planet to freeze over. Over the past billion years Earth's average temperature has stayed close to 14-15° C, oscillating between warm greenhouse states and cold icehouse states. We live with variation, but a variation with limits. Paleoclimatology is the science of understanding and explaining those variations, those limits, and the forces that control them. Without that understanding we will not be able to foresee future change accurately as our population grows. Our impact on the planet is now equal to a geological force, such that many geologists now see us as living in a new geological era - the Anthropocene.

Paleoclimatology describes Earth's passage through the greenhouse and icehouse worlds of the past 800 million years, including the glaciations of Snowball Earth in a world that was then free of land plants. It describes the operation of the Earth's thermostat, which keeps the planet fit for life, and its control by interactions between greenhouse gases, land plants, chemical weathering, continental motions, volcanic activity, orbital change and solar variability. It explains how we arrived at our current understanding of the climate system, by reviewing the contributions of scientists since the mid-1700s, showing how their ideas were modified as science progressed. And it includes reflections based on the author's involvement in palaeoclimatic research.

The book will transform debate and set the agenda for the next generation of thought about future climate change. It will be an invaluable course reference for undergraduate and postgraduate students in geology, climatology, oceanography and the history of science.

"A real tour-de-force! An outstanding summary not only of the science and what needs to be done, but also the challenges that are a consequence of psychological and cultural baggage that threatens not only the survival of our own species but the many others we are eliminating as well."

Peter Barrett

Emeritus Professor of Geology, Antarctic Research Centre, Victoria University of Wellington, New Zealand

"What a remarkable and wonderful synthesis. . . it will be a wonderful source of [paleoclimate] information and insights."

Christopher R. Scotese

Professor, Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL, USA

Author Biography xi
Acknowledgement xiii
1 Introduction 1
1. 1 What is Palaeoclimatology? 1
1. 2 What Can Palaeoclimatology Tell Us About Future Climate Change? 2
1. 3 Using Numerical Models to Aid Understanding 4
1. 4 The Structure of This Book 4
1. 5 Why is This History Not More Widely Known? 6
References 7
2 The Great Cooling 9
2. 1 The Founding Fathers 9
2. 2 Charles Lyell, 'Father of Palaeoclimatology' 13
2. 3 Agassiz Discovers the Ice Age 19
2. 4 Lyell Defends Icebergs 22
References 28
3 Ice Age Cycles 31
3. 1 The Astronomical Theory of Climate Change 31
3. 2 James Croll Develops the Theory 33
3. 3 Lyell Responds 35
3. 4 Croll Defends His Position 36
3. 5 Even More Ancient Ice Ages 37
3. 6 Not Everyone Agrees 38
References 39
4 Trace Gases Warm The Planet 41
4. 1 De Saussure's Hot Box 41
4. 2 William Herschel's Accidental Discovery 41
4. 3 Discovering Carbon Dioxide 42
4. 4 Fourier, the 'Newton of Heat' Discovers the 'Greenhouse Effect' 43
4. 5 Tyndall Shows How the 'Greenhouse Effect' Works 44
4. 6 Arrhenius Calculates How CO2 Affects Air Temperature 47
4. 7 Chamberlin's Theory of Gases and Ice Ages 49
References 53
5 Changing Geography Through Time 57
5. 1 The Continents Drift 57
5. 2 The Sea Floor Spreads 63
5. 3 The Dating Game 71
5. 4 Base Maps for Palaeoclimatology 72
5. 5 The Evolution of the Modern World 74
References 77
6 Mapping Past Climates 81
6. 1 Climate Indicators 81
6. 2 Palaeoclimatologists Get to Work 82
6. 3 Refining Palaeolatitudes 86
6. 4 Oxygen Isotopes to the Rescue 87
6. 5 Cycles and Astronomy 88
6. 6 Pangaean Palaeoclimates (Carboniferous, Permian, Triassic) 91
6. 7 Post-Break Up Palaeoclimates (Jurassic, Cretaceous) 97
6. 8 Numerical Models Make Their Appearance 104
6. 9 From Wegener to Barron 110
References 110
7 Into the Icehouse 117
7. 1 Climate Clues from the Deep Ocean 117
7. 2 Palaeoceanography 118
7. 3 The World's Freezer 124
7. 4 The Drill Bit Turns 126
7. 5 Global Cooling 131
7. 6 Arctic Glaciation 138
References 141
8 Greenhouse Gas Theory Matures 147
8. 1 CO2 in the Atmosphere and Ocean (1930-1955) 147
8. 2 CO2 in the Atmosphere and Ocean (1955-1979) 149
8. 3 CO2 in the Atmosphere and Ocean (1979-1983) 161
8. 4 Biogeochemistry: The Merging of Physics and Biology 166
8. 5 The Carbon Cycle 167
8. 6 Ocean Carbon 170
8. 7 A Growing International Emphasis 173
8. 8 Reflection on Developments 174
References 176
9 Measuring and Modelling CO2 Back Through Time 183
9. 1 CO2 - The Palaeoclimate Perspective 183
9. 2 Modelling CO2 Back Through Time 187
9. 3 The Critics Gather 191
9. 4 Fossil CO2 197
9. 5 Measuring CO2 Back Through Time 199
9. 6 CO2, Temperature, Solar Luminosity, and the Ordovician Glaciation 204
9. 7 Some Summary Remarks 215
References 216
10 The Pulse of the Earth 223
10. 1 Climate Cycles and Tectonic Forces 223
10. 2 Ocean Chemistry 232
10. 3 Black Shales 235
10. 4 Sea Level 238
10. 5 Biogeochemical Cycles, Gaia and Cybertectonic Earth 240
10. 6 Meteorite Impacts 242
10. 7 Massive Volcanic Eruptions and Biological Extinctions 246
10. 8 An Outrageous Hypothesis: Snowball Earth 252
References 259
11 Numerical Climate Models and Case Histories 267
11. 1 CO2 and General Circulation Models 267
11. 2 Climate Sensitivity 270
11. 3 CO2 and Climate in the Early Cenozoic 272
11. 4 The First Great Ice Sheet 276
11. 5 Hyperthermal Events 280
11. 6 Case History - The Palaeocene - Eocene Boundary 282
11. 7 Case History - The Mid - Miocene Climatic Optimum 287
11. 8 Case History - The Pliocene 296
References 305
12 Solving the Ice Age Mystery - The Deep Ocean Solution 315
12. 1 Astronomical Drivers 315
12. 2 An Ice Age Climate Signal Emerges from the Deep Ocean 317
12. 3 Flip-Flops in the Conveyor 324
12. 4 Ice Age CO2 Signal Hidden on Deep Sea Floor 326
12. 5 A Surprise Millennial Signal Emerges 327
12. 6 Ice Age Productivity 331
12. 7 Observations on Deglaciation and Past Interglacials 333
12. 8 Sea Level 335
12. 9 Natural Climatic Envelopes 337
References 338
13 Solving the Ice Age Mystery - The Ice Core Tale 345
13. 1 The Great Ice Sheets 345
13. 2 The Greenland Story 347
13. 3 Antarctic Ice 350
13. 4 Seesaws 354
13. 5 CO2 in the Ice Age Atmosphere 362
13. 6 The Ultimate Climate Flicker - The Younger Dryas Event 373
13. 7 Problems in the Milankovitch Garden 374
13. 8 The Mechanics of Change 377
References 395
14 The Holocene Interglacial 403
14. 1 Holocene Climate Change 403
14. 2 The Role of Greenhouse Gases - Carbon Dioxide and Methane 417
14. 3 Climate Variability 427
References 432
15 The Late Holocene and the Anthropocene 437
15. 1 The Medieval Warm Period and the Little Ice Age 437
15. 2 Solar Activity and Cosmic Rays 455
15. 3 Volcanoes and Climate 466
15. 4 Sea Level 468
15. 5 The End of the Little Ice Age 476
15. 6 The Anthropocene 490
References 494
16 Putting It All Together 507
16. 1 A Fast Evolving Subject 507
16. 2 Natural Envelopes of Climate Change - Earth's Thermostat 508
16. 3 Evolving Knowledge 510
16. 4 Where is Climate Headed? 515
16. 5 Some Final Remarks 518
16. 6 What Can Be Done? 520
References 523
Appendix 1: Further Reading 527
Appendix 2: List of Figure Sources and Attributions 529
Index 539