Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized CLIMATE CHANGERISKS CLIMATE AND FOODSECURITY IN BANGLADESH CLIMATE CHANGE RISKS AND FOOD SECURITY IN BANGLADESH Winston H. Yu, Mozaharul Alam, Ahmadul Hassan, Abu Saleh Khan, Alex C. Ruane, Cynthia Rosenzweig, David C. Major and James Thurlow publishing for a sustainable future London • Washington, DC First published in 2010 by Earthscan © World Bank, 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: 978-1-84971-130-2 hardback Typeset by JS Typesetting Ltd, Porthcawl, Mid Glamorgan Cover design by Susanne Harris A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Climate change risks and food security in Bangladesh / Winston H. Yu … [et al]. p. cm. Includes bibliographical references and index. ISBN 978-1-84971-130-2 (hbk.) 1. Crops and climate–Bangladesh. 2. Climatic change–Bangladesh. 3. Food security–Environmental aspects– Bangladesh. 4. Agricultural productivity–Environmental aspects–Bangladesh. 5. Agriculture–Economic aspects– Bangladesh. I. Yu, Winston H. S600.64.B3C65 2010 363.8’2095492–dc22 2009053662 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. Printed and bound in the UK by the Cromwell Press Group. The paper used is FSC certified. Contents List of Figures and Tables vii 5.3 Incorporating Coastal Inundation Acknowledgements xi Effects 48 Foreword by Isabel M. Guerrero xiii 5.4 Projections of Future Potential Executive Summary xv Unflooded Production (Climate Only) 49 Glossary of Terms xxi 5.5 Projections of Future Projected Flood Acronyms xxiii Damages 52 5.6 Projections of Potential Coastal 1 INTRODUCTION 1 Inundation Damages 53 1.1 Objectives of Study 2 5.7 Projections of Integrated Damages 53 1.2 Literature Review 2 5.8 Using the Crop Model to Simulate 1.3 Integrated Modelling Methodology 3 Adaptation Options 56 1.4 Organization of Study 4 6 ECONOMY-WIDE IMPACTS OF CLIMATE 2 VULNERABILITY TO CLIMATE RISKS 5 RISKS 60 2.1 The Success of Agriculture 6 6.1 Integrating Climate Effects in an 2.2 Living with Annual Floods 10 Economy-wide Model 61 6.2 Economic Impacts of Existing 2.3 Lean Season Water Availability 15 Climate Variability 64 2.4 Sea level Rise in Coastal Areas 17 6.3 Additional Economic Impacts of 2.5 Regional Hydrology Issues 19 Climate Change 72 3 FUTURE CLIMATE SCENARIOS 21 7 ADAPTATION OPTIONS IN THE 3.1 Future Estimated Precipitation and AGRICULTURE SECTOR 82 Temperature 22 7.1 Identifying and Evaluating 3.2 Future Sea level Rise 26 Adaptation Options 83 4 FUTURE FLOOD HYDROLOGY 28 8 THE WAY FORWARD – TURNING IDEAS 4.1 GBM Basin Model Development 28 TO ACTION 105 4.2 National Hydrologic Super Model 30 8.1 A Framework for Assessing the 4.3 Approach to Modelling Future Flood Economics of Climate Change 107 Changes 30 4.4 Future Changes over the Ganges- ANNEX 1 – Using DSSAT to Model Brahmaputra-Meghna Basin 31 Adaptation Impacts 108 4.5 Future Flood Characteristics and ANNEX 2 – Description of the CGE Model 113 Analysis 33 ANNEX 3 – Constructing the Social Accounting Matrix for Bangladesh 119 5 FUTURE CROP PERFORMANCE 41 5.1 Development of the Baseline Period 42 References 133 5.2 Developing Flood Damage Functions 46 Index 139 List of Figures and Tables 4.3 Percentage change in discharges in Figures (a) the 2030s and (b) the 2050s for A2 1.1 Multi-stage integrated framework scenario in August 33 methodology 3 4.4 Percentage change in discharges in 2.1 Agricultural and total GDP growth (a) the 2030s and (b) the 2050s for A2 trends, 1975–2008 7 scenario in May 34 2.2 Historical trends in rice production 4.5 Total change in national flooded area quantities in Bangladesh, 1972–2006 8 for (a) 2030s A2, (b) 2030s B1, 2.3 Historical trends in land area under rice (c) 2050s A2, (d) 2050s B1 36 cultivation in Bangladesh, 1972–2006 8 4.6 Yearly peak levels at Jamuna station 2.4 Decomposition of historical Aman rice for the baseline and model production trends into land area and experiments (2030s) 37 yield contributions, 1972–2006 9 4.7 Average hydrographs (baseline, 2030s, 2.5 Observed yields for major staples 2050s) for MIROC GCM and A2 (kg/ha) 9 scenario on Teesta River 38 2.6 Time-series of flood-affected areas 4.8 Average hydrographs (baseline, 2030s, (km2) in Bangladesh (1954–2004) 11 2050s) for GFDL GCM and A2 scenario 2.7 Annual and seasonal precipitation on Meghna River 38 time-series (mm) averaged across 4.9 Average hydrographs on the Gorai Bangladesh Meteorological River (baseline, 2030s, and 2050s – Department stations 12 for CCSM A2 scenario) and plus/ 2.8 Average discharges in 1998 and 2002 minus one standard deviation bounds 39 for (a) Brahmaputra, (b) Ganges and 5.1 Baseline sub-regional yields with flood (c) Meghna rivers 13 damages applied (as a percentage of 2.9 Cropping calendar corresponding to undamaged yields) 48 flood land type 14 5.2 Percentage change (versus the 2.10 Aman crop production loss curve as a baseline undamaged simulation) in function of combined discharge 16 national potential production of a) aus, 2.11 Locations of coastal water level b) aman, c) boro and d) wheat 50 stations 17 5.3 Percentage change (versus the 2.12 Ganges-Brahmaputra-Meghna river baseline flood-only simulation) in basin 20 national potential production affected 3.1 Monthly, annual and seasonal by basin floods of a) aus and b) aman temperature changes 24 (boro and wheat are assumed to be 3.2 Monthly, annual and seasonal flood-free) 53 precipitation changes 25 5.4 Percentage of production lost to 4.1 Validated discharges from 1998–2007 coastal inundation associated with at (a) Bahadurabad (b) Hardinge Bridge 29 sea level rise in each coastal region 4.2 Temperature changes for A2 scenario sub-region (9–16) for three future over GBM basin (the 2050s) 32 scenarios, as compared to the baseline period (for A2 SRES) 54 viii Climate Change Risks and Food Security in Bangladesh 5.5 Percentage change (versus the 2.4 Peak discharge and timing during baseline flood-affected simulation) in extreme flood years 12 national potential production with the 2.5 Typical crop calendar for four different combined effects of CO2, temperature rice varieties 14 and precipitation, and basin flooding of 2.6 Hydrological regions and flood land a) aus, b) aman, c) boro and d) wheat 55 types 15 5.6 Regional production changes from 2.7 Summary of drought severity areas in baseline (per cent) for 2050s (a) aman, Bangladesh by crop season (in Mha) 16 (b) aus, (c) boro and (d) wheat 57 2.8 Estimated trends in water level of 6.1 Losses in total national rice production different stations along the coastline 18 due to existing climate variability, 2.9 Area affected by low, moderate and 2005–50 66 high salinity level (in 2005) 19 6.2 Losses in national rice production by 3.1 IPCC AR4 global circulation models 22 crop due to existing climate variability, 3.2 Summary precipitation statistics 2005–50, (a) aus, (b) aman, (c) boro 67 averaged across Bangladesh 6.3 Decomposing regional rice production (1960–2001) 26 losses due to existing climate 3.3 Sea level rise impacts on flood land variability, 2005–50 69 types 26 6.4 Losses in national agricultural GDP 4.1 The sub-regions with hydrological due to existing climate variability, region, agro-ecological zone and 2005–50 69 districts 32 6.5 Losses in national total GDP due to 4.2 Estimated average change (per cent) existing climate variability, 2005–50 71 in discharge across all model 6.6 Losses in total national rice production experiments 33 due to climate change, 2005–50 73 4.3 Modelled baseline season flood land 6.7 Losses in national rice production by type distribution for each month (ha) 35 crop due to climate change, 2005–50 75 4.4 Protected areas flood control and 6.8 Deviation in average final year rice drainage infrastructure (FCDI) 35 production from the Existing Variability 4.5 Number of model experiments Scenario under the Average Climate exceeding one standard deviation Change Scenario, 2050 76 bounds on baseline (2030s/2050s) and 6.9 Deviation in average final year rice 2050s average estimated change in production from the Existing Variability area flooded 36 Scenario under different emissions 4.6 Peak water level summary for the 2050s 37 scenarios, 2050 76 5.1 Sub-regional agricultural information 43 6.10 Losses in national agricultural GDP 5.2 Climate information for each sub- due to climate change, 2005–50 77 region: the representative BMD station, 6.11 Losses in national total GDP due to its code and annual mean climate climate change, 2005–50 79 statistics during the 1970–99 baseline 6.12 Cumulative discounted losses due to period 44 climate change as a share of total 5.3 Soil profile information