‘This book takes a unique and powerful approach to METHANE the global methane problem. The organization by the key sources (termites, rice, ruminants etc.) illustrates the global nature of the challenge and directly points METHANE the way to novel solutions.’ Peter M. Groffman, Cary Institute of Ecosystem Studies, USA EDITED BY BY EDITED and CLIMATE Methane is a powerful greenhouse gas and is estimated to be responsible for approximately a fifth of manmade global warming. Per kilogram, its global warming potential is 25 times that of carbon dioxide – and global warming is likely to enhance methane release from a number D CHANGE of sources. Current natural and manmade sources include many S PETE REAY, AVE where methane-producing micro-organisms can thrive in anaerobic and conditions, particularly ruminant livestock, rice cultivation, landfill, wastewater, wetlands and marine sediments. CLI This timely and authoritative book provides the only comprehensive and balanced overview of our current knowledge of sources of methane and how these might be M controlled to limit future climate change. It highlights how sources of methane ITH AND M might themselves be affected by climate change, and shows how numerous sources of methane have the potential to be more easily addressed than sources of carbon dioxide, and can therefore contribute significantly to climate change mitigation ATE in the 21st century. A ND Dave Reay is a senior lecturer in carbon management in the School of Geosciences at R the University of Edinburgh. He is the author of several climate change books and CHANGE É runs the Greenhouse Gas Online website, which has won several awards. van Pete Smith is the Royal Society Wolfson Professor of Soils and Global Change, in the School of Biological Sciences at the University of Aberdeen, UK. André van Amstel is Assistant Professor in the Department of Environmental Sciences Ams at Wageningen University, The Netherlands. TEL publishing for a sustainable future www.earthscan.co.uk www.earthscan.co.uk publishing for a sustainable future Earthscan strives to minimize its impact on the environment Cover photos: Cows at pasture © Tracy Tucker/istockphoto.com Bicycles in a Rice Field © Joel Carillet/istockphoto.com Leaves/gas hob © Dave Reay EDITED BY DAVE REAY, PETE SMITH Climate Change/Agriculture and Food/Environmental Science AND ANDRÉ van AmsTEL 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page i Methane and Climate Change 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page ii 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page iii Methane and Climate Change Edited by Dave Reay, Pete Smith and André van Amstel London • Washington, DC 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page iv First published in 2010 by Earthscan Copyright © Dr David R. Reay, Professor Pete Smith and Dr André van Amstel, 2010 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 expressly permitted by law, without the prior, written permission of the publisher. Earthscan Ltd, Dunstan House, 14a St Cross Street, London EC1N 8XA, UK Earthscan LLC, 1616 P Street, NW, Washington, DC 20036, USA Earthscan publishes in association with the International Institute for Environment and Development For more information on Earthscan publications, see www.earthscan.co.uk or write to [email protected] ISBN 978-1-84407-823-3 Typeset by FiSH Books, Enfield Cover design by Susanne Harris A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Methane and climate change / edited by Dave Reay, Pete Smith, and André van Amstel. p. cm. Includes bibliographical references and index. ISBN 978-1-84407-823-3 (hardback) 1. Atmospheric methane—Environmental aspects. 2. Methane—Environmental aspects. 3. Climatic changes. I. Reay, Dave, 1972– II. Smith, Pete, 1965– III. Amstel, André van. QC879.85.M48 2010 551.6—dc22 2009052501 At Earthscan we strive to minimize our environmental impacts and carbon footprint through reducing waste, recycling and offsetting our CO2 emissions, including those created through publication of this book. For more details of our environmental policy, see www.earthscan.co.uk. This book was printed in the UK by TJ International, an ISO 14001 accredited company. The paper used is FSC certified and the inks are vegetable based. 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page v Contents 1 Methane Sources and the Global Methane Budget 1 Dave Reay, Pete Smith and André van Amstel 2 The Microbiology of Methanogenesis 14 Alfons J. M. Stams and Caroline M. Plugge 3 Wetlands 27 Torben R. Christensen 4 Geological Methane 42 Giuseppe Etiope 5 Termites 62 David E. Bignell 6 Vegetation 74 Andy McLeod and Frank Keppler 7 Biomass Burning 97 Joel S. Levine 8 Rice Cultivation 115 Franz Conen, Keith A. Smith and Kazuyuki Yagi 9 Ruminants 136 Francis M. Kelliher and Harry Clark 10 Wastewater and Manure 151 Miriam H. A. van Eekert, Hendrik Jan van Dooren, Marjo Lexmond and Grietje Zeeman 11 Landfills 175 Jean E. Bogner and Kurt Spokas 12 Fossil Energy and Ventilation Air Methane 201 Richard Mattus and Åke Källstrand 13 Options for Methane Control 211 André van Amstel 14 Summary 242 André van Amstel, Dave Reay and Pete Smith Contributors 247 Acronyms and abbreviations 250 Index 253 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page vi 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page vii To Glyn and Allan 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page viii 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page 1 1 Methane Sources and the Global Methane Budget Dave Reay, Pete Smith and André van Amstel Introduction When the late-18th-century Italian Physicist Alessandro Volta first identified methane (CH4) as being the flammable gas in the bubbles that rose from a waterlogged marsh, he could not have guessed how imPortant this gas would Prove to be to human society in the centuries that followed. Today CH4 is used throughout the world as both an industrial and domestic fuel source. Its exPloitation has helPed drive sustained economic develoPment and it has long Provided a lower-carbon energy alternative to coal and oil. As an energy source it remains highly attractive and much sought after; indeed, energy from CH4 (in the form of natural gas) has Played a major role in the UK meeting its Kyoto Protocol commitments to reduce greenhouse gas emissions by allowing a switch from coal firing of Power stations to gas firing. However, CH4 is now increasingly being considered as a leading greenhouse gas in its own right. At the time that Volta was collecting his bubbles of marsh-gas, CH4 concentrations in the atmosphere stood at around 750 parts per billion (ppb) and it was almost a century later that John Tyndall demonstrated its powerful infrared absorption properties and its role as a greenhouse gas. Like the other two main anthropogenic greenhouse gases – carbon dioxide (CO2) and nitrous oxide (N2O) – the concentration of CH4 in the atmosphere has increased raPidly since Pre-industrial times. Ice core records, and more recently atmospheric samples, show that since the beginning of the industrial era concentrations have more than doubled to their current high of over 1750 ppb (Figure 1.1). This concentration far exceeds the maximum concentration of CH4 in the atmosphere at any time in the preceding 650,000 years, and is estimated to be resulting in an additional radiative forcing of about 0.5 watts per metre squared compared to the level in 1750. 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page 2 2 METHANE AND CLIMATE CHANGE Figure 1.1 Atmospheric concentrations of carbon dioxide, methane and nitrous oxide over the last 1000 years Source: Reproduced with permission from the Intergovernmental Panel on Climate Change. Though these concentrations are much lower than those of CO2 (currently ~386 parts per million – ppm), CH4 is more effective at absorbing and re- emitting infrared radiation (heat). Indeed, the global warming potential (GWP) of CH4 on a mass basis is 25 times that of CO2 over a 100-year time horizon (see Box 1.1). 3522 EARTH Methane & Climate Ch.qxd:3522 EARTH Methane & Climate Ch.qxd 13/5/10 09:48 Page 3 METHANE SOURCES AND THE GLOBAL METHANE BUDGET 3 Box 1.1 Global warming potential GWP compares the direct climate forcing of different greenhouse gases relative to that of CO2. The GWP combines the capacity of a gas to absorb infrared radiation, its lifetime in the atmosphere, and the length of time over which its effects on the earth’s climate need to be quantified (the time horizon). In the case of CH4 it is also adjusted to take account of indirect effects via the enhancement of tropospheric ozone, stratospheric water vapour and production of CO2 resulting from its destruction in the atmosphere. So, as CH4 has an effective climate-forcing lifetime in the atmosphere of only 12 years, CH4 has a GWP of 72 over a 20-year time horizon, but a GWP of 25 over a 100-year time horizon and 7.6 over a 500-year time horizon.