Ocean Acidification: Challenges Facing Science and Society PDF
Preview Ocean Acidification: Challenges Facing Science and Society
Ocean Acidifi cation This page intentionally left blank Ocean Acidifi cation EDITED BY Jean-Pierre Gattuso Senior Research Scientist at Centre National de la Recherche Scientifi que (CNRS) and Universite’ Pierre et Marie Curie – Paris 6, France Lina Hansson Project Manager EPOCA (European Project on Ocean Acidifi cation), Centre National de la Recherche Scientifi que (CNRS), France 1 1 Great Clarendon Street, Oxford ox2 6dp Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide in Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offi ces in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Published in the United States by Oxford University Press Inc., New York © Oxford University Press 2011 The moral rights of the authors have been asserted Database right Oxford University Press (maker) First published 2011 Reprinted 2012 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, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose the same condition on any acquirer British Library Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data Data available Typeset by SPI Publisher Services, Pondicherry, India Printed in Spain on acid-free paper by Grafos SA ISBN 978-0-19-959108-4 (Hbk.) 978-0-19-959109-1 (Pbk.) 3 5 7 9 10 8 6 4 2 Foreword Much of the discussion regarding the impacts of the content of our ocean is so vast that there is no chance ongoing build-up of fossil-fuel CO in our atmos- that our activities will signifi cantly change it this is 2 phere has been focused on issues such as the loss of not the case for carbonate ion. The fossil-fuel CO 2 coastal property as the result of rising sea level, the already taken up by surface-ocean water has used further desiccation of the earth’s dry lands, and the up about 30% of the available carbonate ions and, as intrusion of destructive insects into our forests. time goes on, this fraction will increase. However, there is another potential threat to the Fortunately, the surface waters of the ocean are well-being of our planet that has received less atten- highly supersaturated with respect to the mineral- tion, namely the gradual acidifi cation of the ocean. phase calcite formed by coccolithophores, foraminif- The fate of much of the CO we produce will be to era, and oysters. While the extent of supersaturation 2 enter the ocean. In a sense, we are fortunate that with respect to the mineral aragonite formed by ocean water is endowed with the capacity to absorb clams, mussels, and coral is somewhat smaller, far more CO per litre than were it salt free. Instead of there still is a healthy margin before the build-up of 2 just dissolving, as it would in distilled water, the CO CO becomes large enough to force these organisms 2 2 reacts with carbonate and borate ions dissolved in to build their houses in water undersaturated with the sea, thereby increasing the concentration of bicar- respect to aragonite. bonate ions. That’s the good part, for already roughly So, one might ask, what’s the problem? Unless 30% of the CO we have produced by burning coal, we raise the CO level in the atmosphere to a level 2 2 oil, and natural gas has been taken up by the sea. which would create huge problems for us and our Over the next few hundred years, this fraction will fellow inhabitants of the continents, most of the sur- increase, thus reducing its climatic impacts. face ocean will remain supersaturated with respect But there is a fl ip side to this. As the excess CO to both aragonite and calcite. The answer is that it’s 2 content of seawater increases, its hydrogen ion not merely an either/or situation where organisms concentration undergoes a parallel increase. happily produce their CaCO houses as long as the 3 Consequently its acidity rises. This increase will water is supersaturated, and go over the brink of make life more diffi cult for those marine organisms incapability when the water becomes undersatu- that are housed in solid CaCO . The clams, oysters, rated. Instead, experiments show that as the con- 3 and mussels we dine on live in shells made of centration of carbonate ions goes down, so does the CaCO ; the coccolithophores and foraminifera rate at which at least some types of marine organ- 3 which are at the base of the marine food chain on isms are able to precipitate CaCO . So, the challenge 3 which fi sh depend are also protected by CaCO . The is to establish, for each type of organism, how they 3 coral reefs that form one of the major habitats for respond to lowered carbonate concentration, and what we refer to as our planet’s biodiversity are then to determine how it affects their ability to hold built of CaCO . on to what we refer to as their ecological niche. 3 To form their CaCO housing, marine organisms Concern focuses on the world’s coral reefs. It is 3 combine calcium ions with carbonate ions. Although clear that they are under stress created by like the O content of our atmosphere, the calcium overfi shing, excess nitrate availability, fl ooding 2 v vi FOREWORD with turbid river water, etc. The impacts of this behoves us to increase our efforts to understand the extra stress become clear, particularly during hot impacts of ocean acidifi cation. Not only will this summers. The dinofl agellates which inhabit the put us in a better position to educate the public coral polyps vanish causing the reef to lose its col- regarding the dangers it holds, but it will also allow our. Some reefs recover from this so-called bleach- us to evaluate whether there are actions we could ing. Others do not. The steady reduction in carbonate take to counter the coming impacts. This book ions associated with ocean acidifi cation is likely to brings together much of our knowledge regarding aggravates the situation, adding yet another chal- ocean acidifi cation and also points out the gaps that lenge to already threatened corals. could be fi lled by further research. What can we do? Of course, ideally we would Wallace S. Broecker strive to slow down and eventually bring to a halt Newberry Professor of Earth and the rise in CO . But, as the opponents of action cur- 2 Environmental Sciences rently hold the upper hand, during the next couple Lamont-Doherty Earth Observatory of of decades the rate of increase of CO is likely to 2 Columbia University accelerate rather than slow. This being the case, it Preface In less than fi fteen years ocean acidifi cation has biogeochemistry (Chapters 11 and 12), and the policy emerged as a key research priority for marine sci- implications, and mitigation scenarios (Chapters 13 ence and has recently begun to gain visibility in and 14). Finally, Chapter 15 provides a summary of the political agendas. Even though the history of anthro- knowns and the unknowns, as well as perspectives. pogenic ocean acidifi cation as a research topic is We are very grateful to the authors for their dedica- brief, ocean acidifi cation was triggered, like global tion and for producing landmark contributions. All warming, by the industrial revolution more than 200 chapters were reviewed by at least one of the authors years ago. Since 1800, the oceans have absorbed of another chapter as well as by ourselves. We are also about one-third of the carbon dioxide produced by indebted to Joanie A. Kleypas and Stephen V. Smith man. Without this moderating capacity of the oceans, who reviewed Chapter 1, to Helen Findlay, who atmospheric levels of carbon dioxide would have reviewed Chapter 7, and to the publication team at been considerably higher and, consequently, the Oxford University Press for its support. Last but not effect on Earth’s climate more pronounced. As ocean least, we are very grateful for the support of the acidifi cation continues at a rate that is probably European Commission through the European Project unprecedented in the history of Earth, our under- on Ocean Acidifi cation (EPOCA) during the prepara- standing of its possible impacts on marine life slowly tion of this book. All EPOCA participants have con- becomes clearer. The picture that appears is com- tributed to providing a very lively and exciting plex, but indicates negative consequences on some working environment to both of us. marine organisms and ecosystems. This is a contribution to two core projects of The number of papers on ocean acidifi cation the International Geosphere-Biosphere Programme increased considerably after 2004. With a total (IGBP), the Integrated Marine Biogeochemistry and number of more than 800 papers, the time is ripe to Ecosystem Research (IMBER) project, and the produce the fi rst authoritative book on ocean acidi- Surface Ocean Lower Atmosphere Study (SOLAS), fi cation. Structured around fi fteen chapters, this that have jointly developed the SOLAS-IMBER book takes the reader through the history and recent Ocean Acidifi cation (SIOA) working group. research on ocean acidifi cation, from the chemical Last but not least, we thank our families for their background to the biological and biogeochemical support and patience. consequences. It is organized in four parts, refl ect- Jean-Pierre Gattuso and Lina Hansson ing the pluri-disciplinary character of the subject: Villefranche-sur-mer, chemistry (Chapters 1–3), biology (Chapters 4–10), 10th June 2011 vii This page intentionally left blank Contents Foreword v Wallace S. Broecker Preface vii List of abbreviations xiii List of contributors xvii 1 Ocean acidifi cation: background and history 1 Jean-Pierre Gattuso and Lina Hansson 1.1 Introduction 1 1.2 What is ocean acidifi cation? 2 1.3 The biological and biogeochemical processes that are potentially affected 5 1.4 A short history of ocean acidifi cation research 6 1.5 Risks and policy implications 13 1.6 Conclusions 16 1.7 Acknowledgements 17 2 Past changes in ocean carbonate chemistry 21 Richard E. Zeebe and Andy Ridgwell 2.1 Introduction 21 2.2 Seawater carbonate chemistry 22 2.3 Controls on ocean carbonate chemistry 23 2.4 Long-term changes during earth’s history (quasi-steady states) 27 2.5 Ocean acidifi cation events in earth’s history 33 2.6 Conclusions 36 2.7 Acknowledgements 37 3 Recent and future changes in ocean carbonate chemistry 41 James C. Orr 3.1 Introduction 41 3.2 Basic chemistry under change 41 3.3 Atmospheric CO emissions, sources, and sinks during the industrial era 45 2 3.4 Observed changes in ocean carbonate chemistry during recent decades 45 3.5 Future scenarios 47 3.6 Projecting future changes in carbonate chemistry 48 3.7 Conclusions 61 3.8 Acknowledgements 63
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