Earth’s Climate Evolution The Geological Time Scale for the Phanerozoic Aeon Era Period Epoch Base Age (Ma) Cenozoica Quaternary Holocene 0.0117 Pleistocene 2.6 Neogene Pliocene 5.3 Miocene 23 Palaeogene Oligocene 33.9 Eocene 55.8 Palaeocene 65.5 Mesozoic Cretaceous Upper 99.6 Lower 145.5 Jurassic Upper 161.2 Middle 175.6 Lower 199.6 Triassic Upper 228.7 Middle 245.9 Lower 251 Palaeozoic Permian Upper 260.4 Middle 270.6 Lower 299 Carboniferous Upper 318.1 Lower 359.2 Devonian Upper 385.3 Middle 397.5 Lower 416 Silurian 443.7 Ordovician 488.3 Cambrian 542 aDuring the 19th century, geological time was divided into Primary, Secondary, Tertiary and Quaternary Eras. Meso- zoic and Palaeozoic strata were regarded as belonging to the Secondary Era. The Tertiary was equivalent to the Cenozoic Era, but without the Quaternary. These older designations were done away with in the latter part of the 20th century, although ‘Tertiary Era’ is often misused for ‘Cenozoic Era’. Of the older terms, ‘Quaternary’ has managed to hang on in the form of a geological period. From the International Stratigraphic Chart for 2010 (see http://www.stratigraphy.org/index.php/ics-chart-timescale, last accessed 29 January 2015). Earth’s Climate Evolution COLIN P. SUMMERHAYES Published in association with the Scott Polar Research Institute This edition first published 2015 © 2015 by John Wiley & Sons, Ltd Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030-5774, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright materialin this book please see our website at www.wiley.com/wiley-blackwell. The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and PatentsAct1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. Limit of Liability/Disclaimer of Warranty: While the publisher and author(s) have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. It is sold on the understanding that the publisher is not engaged in rendering professional services and neither the publisher nor the author shall be liable for damages arising herefrom. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Library of Congress Cataloging-in-Publication Data Summerhayes, C. P. Earth’s Climate Evolution / Colin P. Summerhayes. pages cm Includes bibliographical references and index. ISBN 978-1-118-89739-3 (cloth) 1. Atmospheric carbon dioxide. 2. Climatic changes–Research. 3. Geological carbon sequestration. 4. Paleoclimatology. 5. Ice cores. I. Title. QC879.8.S86 2015 551.609′01–dc23 2015007793 A catalogue record for this book is available from the British Library. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Cover image: The Glacier de Frébouze at the southern edge of the Mont Blanc Massif, taken from the south side of the Italian Val Ferret, near the Col de Ferret, looking north and showing bare rock exposed by glacial retreat, plus abundant scattered erratic blocks left by the shrinking glacier. © Colin Summerhayes, 2007 Set in 9/11pt, TimesLTStd by SPi Global, Chennai, India 1 2015 To my grandchildren, Reid, Torrin and Jove Cockrell and Zoe and Phoebe Summerhayes, in the hope that you can work towards freeing the future from the negative aspects of anthropogenic climate change. Contents Author Biography xi Foreword xiii Acknowledgements xv 1 Introduction 1 References 7 2 The Great Cooling 8 2.1 The Founding Fathers 8 2.2 Charles Lyell, ‘Father of Palaeoclimatology’ 12 2.3 Agassiz Discovers the Ice Age 17 2.4 Lyell Defends Icebergs 20 References 25 3 Ice Age Cycles 28 3.1 The Astronomical Theory of Climate Change 28 3.2 James Croll Develops the Theory 29 3.3 Lyell Responds 32 3.4 Croll Defends his Position 33 3.5 Even More Ancient Ice Ages 34 3.6 Not Everyone Agrees 34 References 35 4 Trace Gases Warm the Planet 37 4.1 De Saussure’s Hot Box 37 4.2 William Herschel’s Accidental Discovery 37 4.3 Discovering Carbon Dioxide 38 4.4 Fourier, the ‘Newton of Heat’, Discovers the ‘Greenhouse Effect’ 39 4.5 Tyndall Shows How the ‘Greenhouse Effect’ Works 40 4.6 Arrhenius Calculates How CO2 Affects Air Temperature 43 4.7 Chamberlin’s Theory of Gases and Ice Ages 45 References 49 5 Moving Continents and Dating Rocks 51 5.1 The Continents Drift 51 5.2 The Seafloor Spreads 56 5.3 The Dating Game 61 viii Contents 5.4 Base Maps for Palaeoclimatology 62 5.5 The Evolution of the Modern World 65 References 68 6 Mapping Past Climates 71 6.1 Climate Indicators 71 6.2 Palaeoclimatologists Get to Work 72 6.3 Palaeomagneticians Enter the Field 75 6.4 Oxygen Isotopes to the Rescue 77 6.5 Cycles and Astronomy 78 6.6 Pangaean Palaeoclimates (Carboniferous, Permian, Triassic) 81 6.7 Post-Break-Up Palaeoclimates (Jurassic, Cretaceous) 87 6.8 Numerical Models Make their Appearance 94 6.9 From Wegener to Barron 98 References 99 7 Into the Icehouse 105 7.1 Climate Clues from the Deep Ocean 105 7.2 Palaeoceanography 106 7.3 The World’s Freezer 111 7.4 The Drill Bit Turns 114 7.5 Global Cooling 119 7.6 Arctic Glaciation 125 References 127 8 The Greenhouse Gas Theory Matures 132 8.1 CO2 in the Atmosphere and Ocean (1930–1955) 132 8.2 CO2 in the Atmosphere and Ocean (1955–1979) 133 8.3 CO2 in the Atmosphere and Ocean (1979–1983) 141 8.4 Biogeochemistry: The Merging of Physics and Biology 144 8.5 The Carbon Cycle 145 8.6 Oceanic Carbon 147 8.7 Measuring CO2 in the Oceans 148 8.8 A Growing International Emphasis 149 8.9 Reflection on Developments 150 References 152 9 Measuring and Modelling CO2 Back through Time 156 9.1 CO2: The Palaeoclimate Perspective 156 9.2 Fossil CO2 157 9.3 Measuring CO2 Back through Time 159 9.4 Modelling CO2 and Climate 165 9.5 The Critics Gather 168 References 176 10 The Pulse of the Earth 181 10.1 Climate Cycles and Tectonic Forces 181 10.2 Ocean Chemistry 188 10.3 Black Shales 190 Contents ix 10.4 Sea Level 193 10.5 Biogeochemical Cycles, Gaia and Cybertectonic Earth 194 10.6 Meteorite Impacts 196 10.7 Massive Volcanic Eruptions 199 References 203 11 Numerical Climate Models and Case Histories 207 11.1 CO2 and General Circulation Models 207 11.2 CO2 and Climate in the Early Cenozoic 211 11.3 The First Great Ice Sheet 215 11.4 Hyperthermal Events 218 11.5 Case History: The Palaeocene–Eocene Boundary 219 11.6 CO2 and Climate in the Late Cenozoic 222 11.7 Case History: The Pliocene 226 References 234 12 Solving the Ice Age Mystery: The Deep-Ocean Solution 240 12.1 Astronomical Drivers 240 12.2 An Ice Age Climate Signal Emerges from the Deep Ocean 242 12.3 The Ice Age CO2 Signal Hidden on the Deep-Sea Floor 248 12.4 Flip-Flops in the Conveyor 249 12.5 A Surprise Millennial Signal Emerges 251 12.6 Ice Age Productivity 253 12.7 Observations on Deglaciation and Past Interglacials 254 12.8 Sea Level 256 References 259 13 Solving the Ice Age Mystery: The Ice Core Tale 264 13.1 The Great Ice Sheets 264 13.2 The Greenland Story 264 13.3 Antarctic Ice 266 13.4 Seesaws 270 13.5 CO2 in the Ice Age Atmosphere 273 13.6 The Ultimate Climate Flicker: The Younger Dryas Event 279 13.7 Problems in the Milankovitch Garden 280 13.8 The Mechanics of Change 282 References 296 14 The Holocene Interglacial 302 14.1 Holocene Climate Change 302 14.2 The Role of Greenhouse Gases: Carbon Dioxide and Methane 311 14.3 Climate Variability 315 References 320 15 Medieval Warming, the Little Ice Age and the Sun 324 15.1 Solar Activity and Cosmic Rays 324 15.2 Solar Cycles in the Geological Record 327 15.3 The Medieval Warm Period and the Little Ice Age 330 15.4 The End of the Little Ice Age 340 x Contents 15.5 The Hockey Stick Controversy 347 15.6 Sea Level 353 References 358 16 Putting It All Together 365 16.1 A Fast-Evolving Subject 365 16.2 Natural Envelopes of Climate Change 366 16.3 Evolving Knowledge 367 16.4 Where is Climate Headed? 373 16.5 Some Final Remarks 375 16.6 What Can Be Done? 377 References 379 Appendix A: Further Reading 381 Appendix B: List of Figure Sources and Attributions 383 Index 389 Author Biography Colin P.