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.

“This is a magnificent book, and is the best in-depth treatment of palaeoclimate that I know: a text that systematically explores the evidence and the detail.” - Jan Zalasiewicz, Geoscientist - The magazine of the Geological Society of London, December 2021

• Author Biography xiAcknowledgement xiii1 Introduction 11.1 What is Palaeoclimatology? 11.2 What Can Palaeoclimatology Tell Us About Future Climate Change? 21.3 Using Numerical Models to Aid Understanding 41.4 The Structure of This Book 41.5 Why is This History Not More Widely Known? 6References 72 The Great Cooling 92.1 The Founding Fathers 92.2 Charles Lyell, ‘Father of Palaeoclimatology’ 132.3 Agassiz Discovers the Ice Age 192.4 Lyell Defends Icebergs 22References 283 Ice Age Cycles 313.1 The Astronomical Theory of Climate Change 313.2 James Croll Develops the Theory 333.3 Lyell Responds 353.4 Croll Defends His Position 363.5 Even More Ancient Ice Ages 373.6 Not Everyone Agrees 38References 394 Trace Gases Warm The Planet 414.1 De Saussure’s Hot Box 414.2 William Herschel’s Accidental Discovery 414.3 Discovering Carbon Dioxide 424.4 Fourier, the ‘Newton of Heat’ Discovers the ‘Greenhouse Effect’ 434.5 Tyndall Shows How the ‘Greenhouse Effect’ Works 444.6 Arrhenius Calculates How CO2 Affects Air Temperature 474.7 Chamberlin’s Theory of Gases and Ice Ages 49References 535 Changing Geography Through Time 575.1 The Continents Drift 575.2 The Sea Floor Spreads 635.3 The Dating Game 715.4 Base Maps for Palaeoclimatology 725.5 The Evolution of the Modern World 74References 776 Mapping Past Climates 816.1 Climate Indicators 816.2 Palaeoclimatologists Get to Work 826.3 Refining Palaeolatitudes 866.4 Oxygen Isotopes to the Rescue 876.5 Cycles and Astronomy 886.6 Pangaean Palaeoclimates (Carboniferous, Permian, Triassic) 916.7 Post-Break Up Palaeoclimates (Jurassic, Cretaceous) 976.8 Numerical Models Make Their Appearance 1046.9 From Wegener to Barron 110References 1107 Into the Icehouse 1177.1 Climate Clues from the Deep Ocean 1177.2 Palaeoceanography 1187.3 The World’s Freezer 1247.4 The Drill Bit Turns 1267.5 Global Cooling 1317.6 Arctic Glaciation 138References 1418 Greenhouse Gas Theory Matures 1478.1 CO2 in the Atmosphere and Ocean (1930–1955) 1478.2 CO2 in the Atmosphere and Ocean (1955–1979) 1498.3 CO2 in the Atmosphere and Ocean (1979–1983) 1618.4 Biogeochemistry: The Merging of Physics and Biology 1668.5 The Carbon Cycle 1678.6 Ocean Carbon 1708.7 A Growing International Emphasis 1738.8 Reflection on Developments 174References 1769 Measuring and Modelling CO2 Back Through Time 1839.1 CO2 – The Palaeoclimate Perspective 1839.2 Modelling CO2 Back Through Time 1879.3 The Critics Gather 1919.4 Fossil CO2 1979.5 Measuring CO2 Back Through Time 1999.6 CO2, Temperature, Solar Luminosity, and the Ordovician Glaciation 2049.7 Some Summary Remarks 215References 21610 The Pulse of the Earth 22310.1 Climate Cycles and Tectonic Forces 22310.2 Ocean Chemistry 23210.3 Black Shales 23510.4 Sea Level 23810.5 Biogeochemical Cycles, Gaia and Cybertectonic Earth 24010.6 Meteorite Impacts 24210.7 Massive Volcanic Eruptions and Biological Extinctions 24610.8 An Outrageous Hypothesis: Snowball Earth 252References 25911 Numerical Climate Models and Case Histories 26711.1 CO2 and General Circulation Models 26711.2 Climate Sensitivity 27011.3 CO2 and Climate in the Early Cenozoic 27211.4 The First Great Ice Sheet 27611.5 Hyperthermal Events 28011.6 Case History – The Palaeocene – Eocene Boundary 28211.7 Case History – The Mid – Miocene Climatic Optimum 28711.8 Case History – The Pliocene 296References 30512 Solving the Ice Age Mystery – The Deep Ocean Solution 31512.1 Astronomical Drivers 31512.2 An Ice Age Climate Signal Emerges from the Deep Ocean 31712.3 Flip-Flops in the Conveyor 32412.4 Ice Age CO2 Signal Hidden on Deep Sea Floor 32612.5 A Surprise Millennial Signal Emerges 32712.6 Ice Age Productivity 33112.7 Observations on Deglaciation and Past Interglacials 33312.8 Sea Level 33512.9 Natural Climatic Envelopes 337References 33813 Solving the Ice Age Mystery – The Ice Core Tale 34513.1 The Great Ice Sheets 34513.2 The Greenland Story 34713.3 Antarctic Ice 35013.4 Seesaws 35413.5 CO2 in the Ice Age Atmosphere 36213.6 The Ultimate Climate Flicker – The Younger Dryas Event 37313.7 Problems in the Milankovitch Garden 37413.8 The Mechanics of Change 377References 39514 The Holocene Interglacial 40314.1 Holocene Climate Change 40314.2 The Role of Greenhouse Gases – Carbon Dioxide and Methane 41714.3 Climate Variability 427References 43215 The Late Holocene and the Anthropocene 43715.1 The Medieval Warm Period and the Little Ice Age 43715.2 Solar Activity and Cosmic Rays 45515.3 Volcanoes and Climate 46615.4 Sea Level 46815.5 The End of the Little Ice Age 47615.6 The Anthropocene 490References 49416 Putting It All Together 50716.1 A Fast Evolving Subject 50716.2 Natural Envelopes of Climate Change – Earth’s Thermostat 50816.3 Evolving Knowledge 51016.4 Where is Climate Headed? 51516.5 Some Final Remarks 51816.6 What Can Be Done? 520References 523Appendix 1: Further Reading 527Appendix 2: List of Figure Sources and Attributions 529Index 539

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.

“This is a magnificent book, and is the best in-depth treatment of palaeoclimate that I know: a text that systematically explores the evidence and the detail.” - Jan Zalasiewicz, Geoscientist - The magazine of the Geological Society of London, December 2021

• Author Biography xiAcknowledgement xiii1 Introduction 11.1 What is Palaeoclimatology? 11.2 What Can Palaeoclimatology Tell Us About Future Climate Change? 21.3 Using Numerical Models to Aid Understanding 41.4 The Structure of This Book 41.5 Why is This History Not More Widely Known? 6References 72 The Great Cooling 92.1 The Founding Fathers 92.2 Charles Lyell, ‘Father of Palaeoclimatology’ 132.3 Agassiz Discovers the Ice Age 192.4 Lyell Defends Icebergs 22References 283 Ice Age Cycles 313.1 The Astronomical Theory of Climate Change 313.2 James Croll Develops the Theory 333.3 Lyell Responds 353.4 Croll Defends His Position 363.5 Even More Ancient Ice Ages 373.6 Not Everyone Agrees 38References 394 Trace Gases Warm The Planet 414.1 De Saussure’s Hot Box 414.2 William Herschel’s Accidental Discovery 414.3 Discovering Carbon Dioxide 424.4 Fourier, the ‘Newton of Heat’ Discovers the ‘Greenhouse Effect’ 434.5 Tyndall Shows How the ‘Greenhouse Effect’ Works 444.6 Arrhenius Calculates How CO2 Affects Air Temperature 474.7 Chamberlin’s Theory of Gases and Ice Ages 49References 535 Changing Geography Through Time 575.1 The Continents Drift 575.2 The Sea Floor Spreads 635.3 The Dating Game 715.4 Base Maps for Palaeoclimatology 725.5 The Evolution of the Modern World 74References 776 Mapping Past Climates 816.1 Climate Indicators 816.2 Palaeoclimatologists Get to Work 826.3 Refining Palaeolatitudes 866.4 Oxygen Isotopes to the Rescue 876.5 Cycles and Astronomy 886.6 Pangaean Palaeoclimates (Carboniferous, Permian, Triassic) 916.7 Post-Break Up Palaeoclimates (Jurassic, Cretaceous) 976.8 Numerical Models Make Their Appearance 1046.9 From Wegener to Barron 110References 1107 Into the Icehouse 1177.1 Climate Clues from the Deep Ocean 1177.2 Palaeoceanography 1187.3 The World’s Freezer 1247.4 The Drill Bit Turns 1267.5 Global Cooling 1317.6 Arctic Glaciation 138References 1418 Greenhouse Gas Theory Matures 1478.1 CO2 in the Atmosphere and Ocean (1930–1955) 1478.2 CO2 in the Atmosphere and Ocean (1955–1979) 1498.3 CO2 in the Atmosphere and Ocean (1979–1983) 1618.4 Biogeochemistry: The Merging of Physics and Biology 1668.5 The Carbon Cycle 1678.6 Ocean Carbon 1708.7 A Growing International Emphasis 1738.8 Reflection on Developments 174References 1769 Measuring and Modelling CO2 Back Through Time 1839.1 CO2 – The Palaeoclimate Perspective 1839.2 Modelling CO2 Back Through Time 1879.3 The Critics Gather 1919.4 Fossil CO2 1979.5 Measuring CO2 Back Through Time 1999.6 CO2, Temperature, Solar Luminosity, and the Ordovician Glaciation 2049.7 Some Summary Remarks 215References 21610 The Pulse of the Earth 22310.1 Climate Cycles and Tectonic Forces 22310.2 Ocean Chemistry 23210.3 Black Shales 23510.4 Sea Level 23810.5 Biogeochemical Cycles, Gaia and Cybertectonic Earth 24010.6 Meteorite Impacts 24210.7 Massive Volcanic Eruptions and Biological Extinctions 24610.8 An Outrageous Hypothesis: Snowball Earth 252References 25911 Numerical Climate Models and Case Histories 26711.1 CO2 and General Circulation Models 26711.2 Climate Sensitivity 27011.3 CO2 and Climate in the Early Cenozoic 27211.4 The First Great Ice Sheet 27611.5 Hyperthermal Events 28011.6 Case History – The Palaeocene – Eocene Boundary 28211.7 Case History – The Mid – Miocene Climatic Optimum 28711.8 Case History – The Pliocene 296References 30512 Solving the Ice Age Mystery – The Deep Ocean Solution 31512.1 Astronomical Drivers 31512.2 An Ice Age Climate Signal Emerges from the Deep Ocean 31712.3 Flip-Flops in the Conveyor 32412.4 Ice Age CO2 Signal Hidden on Deep Sea Floor 32612.5 A Surprise Millennial Signal Emerges 32712.6 Ice Age Productivity 33112.7 Observations on Deglaciation and Past Interglacials 33312.8 Sea Level 33512.9 Natural Climatic Envelopes 337References 33813 Solving the Ice Age Mystery – The Ice Core Tale 34513.1 The Great Ice Sheets 34513.2 The Greenland Story 34713.3 Antarctic Ice 35013.4 Seesaws 35413.5 CO2 in the Ice Age Atmosphere 36213.6 The Ultimate Climate Flicker – The Younger Dryas Event 37313.7 Problems in the Milankovitch Garden 37413.8 The Mechanics of Change 377References 39514 The Holocene Interglacial 40314.1 Holocene Climate Change 40314.2 The Role of Greenhouse Gases – Carbon Dioxide and Methane 41714.3 Climate Variability 427References 43215 The Late Holocene and the Anthropocene 43715.1 The Medieval Warm Period and the Little Ice Age 43715.2 Solar Activity and Cosmic Rays 45515.3 Volcanoes and Climate 46615.4 Sea Level 46815.5 The End of the Little Ice Age 47615.6 The Anthropocene 490References 49416 Putting It All Together 50716.1 A Fast Evolving Subject 50716.2 Natural Envelopes of Climate Change – Earth’s Thermostat 50816.3 Evolving Knowledge 51016.4 Where is Climate Headed? 51516.5 Some Final Remarks 51816.6 What Can Be Done? 520References 523Appendix 1: Further Reading 527Appendix 2: List of Figure Sources and Attributions 529Index 539