Earth Life System. An Introduction to the

Transcription

1 An Introduction to the Earth Life System This undergraduate textbook brings together Earth and biological sciences to explore the co-evolution of the Earth and life over geological time. It examines the interactions and feedback processes between the geosphere, atmosphere, hydrosphere and biosphere. It also explains how the Earth s surface environment involves a complex interplay between these systems. The book opens with an investigation of the physical controls that combine to make Earth a habitable planet. It explores the emergence and persistence of life and the role life plays in global water and carbon cycles. Subsequent chapters demonstrate the interactions and feedback processes between climate, life and geological processes, such as plate tectonics, mountain building and erosion. The evolution of complex life during the Phanerozoic is examined within the context of environmental conditions that lead to patterns of radiation and extinction. The book concludes with an assessment of how and why the Earth s climate has varied over geological time from icehouse to greenhouse conditions, and considers whether life itself is passive or a force for change. An Introduction to the Earth Life System provides a concise overview of the complete Earth system at and above the surface of the Earth throughout its geological history. It is designed for use on intermediate undergraduate courses and incorporates a wealth of features to support student learning. CHARLES COCKELL is Professor of Microbiology at The Open University, Milton Keynes, UK. His academic interests lie in geomicrobiology, astrobiology and space exploration and he has undertaken expeditions to the Arctic and Antarctic, among other places, to study life in extreme environments. Professor Cockell has written and edited six other books including Impossible Extinction (Cambridge University Press, 2003).

2 Cover image: Stromatolites. These are mineralised microbial communities, formed from blue green algae (also called cyanobacteria). Over the last 4000 years, algae growing in this area have trapped detritus and sediment, forming large, living rafts known as microbial mats. The secretion of calcium carbonate by the algae has caused the mats to mineralise, forming the rocklike structures seen here. Stromatolites are known as living fossils because the process of mat formation and mineralisation continues today. Photographed in Hamelin Pool Marine Nature Reserve, Shark Bay, Western Australia.

3 An Introduction to the Earth Life System Authors: Richard Corfield Neil Edwards Nigel Harris

4 University Printing House, Cambridge CB2 8BS, United Kingdom Cambridge University Press is part of t he University of Cambridge. It furthers the University s mission by disseminating knowledge in the pursuit of education, learning and research at the highest international levels of excellence. Information on this title: / First published 2007 Reprinted 2015 This co-published edition first published 2008 Copyright 2007, 2008 The Open University All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, transmitted or utilised in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without written permission from the publisher or a licence from the Copyright Licensing Agency Ltd. Details of such licences (for reprographic reproduction) may be obtained from the Copyright Licensing Agency Ltd, Saffron House, 6 10 Kirby Street, London EC1N 8TS; website Open University course materials may also be made available in electronic formats for use by students of the University. All rights, including copyright and related rights and database rights, in electronic course materials and their contents are owned by or licensed to The Open University, or otherwise used by The Open University as permitted by applicable law. In using electronic course materials and their contents you agree that your use will be solely for the purposes of following an Open University course of study or otherwise as licensed by The Open University or its assigns. Except as permitted above you undertake not to copy, store in any medium (including electronic storage or use in a website), distribute, transmit or retransmit, broadcast, modify or show in public such electronic materials in whole or in part without the prior written consent of The Open University or in accordance with the Copyright, Designs and Patents Act Edited and designed by The Open University. Printed in the United Kingdom by Bell and Bain Ltd, Glasgow This book forms part of an Open University course S279 Our dynamic planet: Earth and life. Details of this and other Open University courses can be obtained from the Student Registration and Enquiry Service, The Open University, PO Box 197, Milton Keynes MK7 6BJ, United Kingdom: tel. +44 (0) , general-enquiries@open.ac.uk British Library Cataloguing in Publication Data available on request Library of Congress Cataloguing in Publication Data available on request ISBN hardback; ISBN paperback 1.1

5 Contents CHAPTER 1 A HABITABLE PLANET 1 Neil Edwards 1.1 How does the Earth differ from other planets? Energy from the Sun The Earth s surface temperature pattern The Earth s air-conditioning and heating systems Earth ocean atmosphere: the support system for life 47 Summary of Chapter 1 57 Learning outcomes for Chapter 1 59 CHAPTER 2 THE CARBON CYCLE 61 Richard Corfield 2.1 Carbon and life Carbon and climate The natural carbon cycle: a question of timescale A system in balance? 93 Summary of Chapter Learning outcomes for Chapter CHAPTER 3 PLATE TECTONICS, CLIMATE AND LIFE 103 Nigel Harris 3.1 Volcanism and the Earth system Volcanic aerosols and climatic change Flood basalts and their effects on climate and life Continental drift and climate Sea-level changes: causes and consequences 130 Summary of Chapter Learning outcomes for Chapter CHAPTER 4 MOUNTAINS AND CLIMATE CHANGE 139 Nigel Harris 4.1 Mountain building and the carbon cycle The uplift of Tibet and the monsoon 142

6 4.3 Global climate change during the Tertiary 153 Summary of Chapter Learning outcomes for Chapter CHAPTER 5 THE EMERGENCE AND PERSISTENCE OF LIFE Former worlds Mat world Empire of the eukaryotes The carnival of the animals The rules of the new evolutionary game 187 Summary of Chapter Learning outcomes for Chapter CHAPTER 6 LIFE IN THE PHANEROZOIC 195 Richard Corfield 6.1 The Proterozoic Phanerozoic transition Radiations and extinctions The greening of the land 217 Summary of Chapter Learning outcomes for Chapter CHAPTER 7 THE EARTH AT EXTREMES The icehouse world Permo-Carboniferous glaciation and subsequent warming The impact of land vegetation A synthesis for the icehouse The Cretaceous greenhouse world Polar climate Low-latitude vegetation and climate Climate reconstructions Geographical framework A surfeit of carbon: the key to the Cretaceous greenhouse Conclusions from the case studies 267 Summary of Chapter Learning outcomes for Chapter 7 269

7 CHAPTER 8 END-OF-BOOK SUMMARY Possible worlds Review of the options Conclusions 274 ANSWERS TO QUESTIONS 275 APPENDICES 294 A The elements 294 B SI fundamental and derived units 295 C The Greek alphabet 296 D Additional figures 297 GLOSSARY 299 FURTHER READING 308 ACKNOWLEDGEMENTS 310 SOURCES OF FIGURES, DATA AND TABLES 313 INDEX 315 vii