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

Auteur

About the Author Colin P. Summerhayes is an Emeritus Associate of the Scott Polar Research Institute of Cambridge University. He has carried out research and managed research programmes on aspects of past climate change in academia, in government laboratories, in intergovernmental and non-governmental organizations, and in industry since obtaining a PhD in Geochemistry from Imperial College, London, in 1970. The cover shows a view of some the numerous small crevassed glaciers typical of the Antarctic Peninsula, which are seen here cutting across the Mid-Jurassic to Lower Cretaceous volcanic rocks of the exposed magmatic core of the ancient island arc underlying the Peninsula, on the east side of the northern entrance to the Lemaire Channel.

Contenu
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 (19301955) 147

8.2 CO2 in the Atmosphere and Ocean (19551979) 149

8.3 CO2 in the Atmosphere and Ocean (19791983) 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 1...