desertification in the third millennium : proceedings of an international conference, dubai, 12-15...

Copyright © 2003 Swets & Zeitlinger B.V., Lisse, The Netherlands
PROCEEDINGS OF AN INTERNATIONAL CONFERENCE, DUBAI, 12–15 FEBRUARY 2000
Desertification in the Third Millennium
Edited by:
Abdulrahman S. Alsharhan United Arab Emirates University, Al-Ain, United Arab Emirates E-mail: [email protected]
Warren W. Wood U.S. Geological Survey, Reston, Virginia, USA E-mail: [email protected]
Andrew S. Goudie University of Oxford, Oxford, United Kingdom E-mail: [email protected]
Abdulrahman Fowler United Arab Emirates University, Al-Ain, United Arab Emirates E-mail: [email protected]
Eissa M Abdellatif Zayed International Prize for the Environment, Dubai, United Arab Emirates E-mail: [email protected]
A.A. BALKEMA PUBLISHERS LISSE / ABINGDON / EXTON (PA) / TOKYO
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ISBN 90 5809 571 1
PART 1. Desertification and Global Climatic Change
David S.G. Thomas Into the Third Millennium: The Role of Stakeholder Groups in Reducing Desertification . . . . . . . . . . . . . . . . . . . . . . . 3
Andrew S. Goudie The Impacts of Global Warming on the Geomorphology of Arid Lands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Victor R. Squires Desertification, Climate Change and the World’s Drylands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Shaw-Wen Sheen, George A. Brook, Bruce L. Railsback and Jean C. Thill Stalagmite Annual Layer Thickness as a Proxy for Enso and Rainfall: Evidence from Drotsky’s Cave, Botswana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Christopher G.ST.C. Kendall, Paul Lake, Dalton H. Weathers III, Venkat Lakshmi, John Althausen and Abdulrahman S. Alsharhan Evidence of Rain Shadow in the Geologic Record: Repeated Evaporite Accumulation at Extensional and Compressional Plate Margins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Stephen Stokes, Andrew S. Goudie, Alison Colls and Asma Al-Farraj Optical Dating as a Tool for Studying Dune Reactivation, Accretion Rates and Desertification Over Decadal, Centennial and Millennial Time-Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Venkat Lakshmi, Christopher G.ST.C. Kendall, John Althausen and Abdulrahman S. Alsharhan Studies of Local Climate Change in United Arab Emirates Using Satellite Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Walid A. Abderrahman and Ibrahim M. Al-Harazin The Impacts of Global Climatic Change on Reference Crop Evapotranspiration, Irrigation Water Demands, Soil Salinity, and Desertification in Arabian Peninsula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Adrian M. Harvey The Response of Dry-region Alluvial Fans to Quaternary Climatic Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Christopher G.ST.C. Kendall, Venkat Lakshmi, John Althausen and Abdulrahman S. Alsharhan Changes in Microclimate Tracked by the Evolving Vegetation Cover of the Holocene Beach Ridges of the United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Daryoush Mehrshahi, David S.G. Thomas and Sarah O’Hara Late Quaternary Palaeoenvironmental Changes, Ardakan Kavir (Playa), Central Iran . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Werner Smykatz-Kloss, Bernd Roscher and Konard Rögner Pleistocene Lakes in Central Sinai, Egypt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Ronald J. Spencer, Wenbo Yang, Sheila M. Roberts and H. Roy Krouse Hydrology and Climate Change (200 to 100 ka), Death Valley, California, USA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Desertification in the Third Millennium. Edited by A.S. Alsharhan, W.W. Wood, A.S. Goudie, A. Fowler and E.M. Abdellatif. © 2003 Swets & Zeitlinger Publishers, Lisse, The Netherlands, ISBN 90 5809 571 1, p. V–VIII.
VI
Navin Juyal, Amal Kar, S.N. Rajaguru and A.K. Singvi Chronostratigraphic Evidence for Episodes of Desertification since the Last Glacial Epoch in the Southern Margin of Thar Desert, India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
PART 2. Biodiversity, Mangroves and other Halophytes and their Conservation Ecosystems
John M. Peacock, Ghalib A. Alhadrami, M.E. Ferguson, R. Karnik, Ian R. McCann and Ali Saleh Desert Forages of the Arabian Peninsula – The Conservation and Utilization of Biodiversity for Sustainable Animal Production in the United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Ahmed S. Khalil, Urlich Saint-Paul and Eisa M. Abdellatif Response of Meiofauna to Mangrove Degradation in a Dry Semi-Desert Coastal Habitat of the Red Sea (Sudan) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
J.C. Dagar Biodiversity of Indian Saline Habitats and Management & Utilization of High Salinity Tolerant Plants with Industrial Application for Rehabilitation of Saline Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Fatima Al-Ansari and Ali A. El-Keblawy An Analysis of Biodiversity of the United Arab Emirates Flora Using Western’s Flora . . . . . . . . . . . . . . . . . . . . . . . . 173
Ghalib A. Alhadrami, Abdullah J. Al-Dakheel, Mahmoud M. Khorshid, Saleh A. Al-Sharaby and Mohamed H. Abdel Gawad Feeding Camels and Sheep Sporobolus Grass Grown in Saline Desert Lands in the United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Abdullah A. Jaradat Halophytes for Sustainable Biosaline Farming Systems in the Middle East . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Vishnu P. Singh Biodiversity, Community Pattern and Status of Indian Mangroves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Ali A. El-Keblawy Effects of Protection from Grazing on Species Diversity, Abundance and Productivity in Two Regions of Abu Dhabi, United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Muhammad Asif Khan and Nasser A. Al-Homaid Remote Sensing Study on Mangrove Depletion Tarut Bay, Saudi Arabia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
PART 3. The Effect of Wind and Water on Soil Erosion and Sand Creep
Hans-Jörg Barth Late Holocene Sedimentation Processes Along the Arabian Gulf Coast in the Jubail Area, Saudi Arabia . . . . 237
Belnap Jayne, Sue Phillips, Mike Duniway and Rich Reynolds Soil Fertility in Deserts: A Review on the Influence of Biological Soil Crusts and the Effect of Soil Surface Disturbance on Nutrient Inputs and Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Larry Boersma and J. Baham Aspects of the Role of Biogeochemical Processes in Soils in the Global Carbon Cycle . . . . . . . . . . . . . . . . . . . . . . . 253
VII
Yann Callot Relations Between Wind Data and Geomorphology in Aeolian Sand Geodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Richard Reynolds, Marith Reheis, Pat Chavez, Jr., Todd Hinkley, Richard Tigges, Gary Clow, David MacKinnon, Paul Lamothe, Nicholas Lancaster, Mark Miller, James Yount, Miguel Velasco, Stuart Sides, Deborah Soltesz, Greg Meeker, Robert Fulton and Jayne Belnap Dust Emission and Deposition in the Southwestern United States – Integrated Field, Remote Sensing, and Modeling Studies to Evaluate Response to Climatic Variability and Land Use . . . . . . . . . . . . . . . . . . 271
Robert H. Webb and Kathryn A. Thomas Recoverability of Severely Disturbed Soils and Vegetation in the Mojave Desert, California, USA . . . . . . . . . . . 283
Giles F.S. Wiggs, Sarah L. O’Hara and B.K. Mamedov Wind Erosion and Dust Deposition in the Aral Sea Region: Possible Consequences of Unsustainable Human Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
Jasem M. Al-Awadhi, Ali Al-Dousari and Abdullah Al-Enezi Barchan Dunes in Northern Kuwait . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Saleh Al-Muzaini Environmental Measures to Control Sand Movement in Kuwait . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
PART 4. Land Degradation and Management in Arid, Semi-Arid and Dry Sub-Humid Areas
William R. Stanley Herero, German and Afrikaner in Arid and Semi-Arid Eastern Namibia: Comparative Technologies for Water Use and Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Ruth Schofield Soil Salinity as a Degradation Process in Spain and Tunisia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Migdam E. Abdelgani, A.G. Osman and S.S. Mohamed Restoring Soil Fertility of Desertified Lands Through Biological Nitrogen Fixation in Sudan . . . . . . . . . . . . . . . . 335
Khaled R. Ben-Mahmoud, Shaban Mansur and A. Al-Gomati Land Degradation and Desertification in Libya . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
Shabbir A. Shahid, Samira A.S. Omar, Raafat Misak and H. Abo Rizq Land Resource Stresses and Degradation in the Arid Environment of Kuwait: An Overview . . . . . . . . . . . . . . . . . 351
Elnur Abdalla Elsiddig Management of Dry Land Forest Reserves in Sudan Based on Participatory Approach . . . . . . . . . . . . . . . . . . . . . . . 361
Banaras Hussain Niazi and Jelte Rozema Introduction of Non-conventional Salt Tolerant Crops Under Salt Affected Arable Land in Pakistan . . . . . . . . . 365
PART 5. Policies and Cost/Benefit for Combating Land Degradation and Desertification
Fouad Kanbour The International Convention on Desertification: the Preservation of Indigenous Technologies in Arab Countries of West Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
Scott Christiansen Lessons from Rural Development of Relevance to Desertification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381
VIII
Adel El-Beltagy Sustainable Management of Rangelands and Agricultural Systems of the Drylands: The ICARDA Experience in Combating Desertification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
Ahmed A.R. Elagib Can Science and Technology Help to Initiate Natural Regreening of the Arabian Peninusula? . . . . . . . . . . . . . . . . 399
Mahlagha Ghorbanli and A. Motamed The Desert Environment in Iran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
PART 6. Application of Remote Sensing and Geographic Information System (GIS) to Study Desertification
John D. Althausen, Jr., Christopher G.ST.C. Kendall, Venkat Lakshmi, Abdulrahman S. Alsharhan and Gregory L. Whittle Using Satellite Imagery and GIS in the Mapping of Coastal Landscapes in an Arid Environment: Khor Al Bazam, Western Abu Dhabi, United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Zeinelabidin S. Rizk and Abdulrahman S. Alsharhan Geographical Information System Modeling of Groundwater Potentiality in the Northeastern Part of the United Arab Emirates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Andy Y. Kwarteng, Raafat F. Misak and Mohammed A. Al-Sudairawi Radarsat Synthetic Aperture Radar (SAR) Imagery Observation of Sand Dunes in Kuwait . . . . . . . . . . . . . . . . . . . 435
Osman Mirghani Mohamed Ali and El Tayeb Osman Adam Application of Remote Sensing for the Assessment of Environmental Changes in Western Kordofan State (Sudan) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445
Mansouri Taoufik, Boussema M. Rached, Albergel Jean and Chaibi Najeh Application of Remote Sensing and GIS to Study Erosion in Tunisia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453
Ibrahim S. Ibrahim, M.M. Ahmed, M.A. Mustafa and Mustafa A. El Hag Preliminary Study of Sand Erosion in South Khartoum Area, Sudan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461
PART 7. Groundwater Resources in Desert Areas
Mohammed Saqar Al Asam Groundwater Situation in the United Arab Emirates: An Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469
Mohammed Rasheeduddin, W.A. Abderrahman and John W. Lloyd Sustainable Development of a Depletable Aquifer: A Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477
Khaled Hadi and M. Al-Senafy Suitability of Groundwater for Irrigation in Kuwait . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487
Preface
The Desertification Conference entitled “Toward Better Management of Arid and Semi-Arid Lands in the Twenty-First Century” was convened in Dubai, UAE, during 12–16 February 2000, under the auspices of the Zayed International Prize for the Environment. This volume contains a representative selection of 53 of the original 125 oral presentations at the conference, which contributed to the following objectives:
• to enhance our understanding of local, regional, and global short and long-term environmental changes; • to convey best practices associated with the ecological management of arid areas; and • to improve our general understanding of desert environments as we are approaching the third millennium.
The papers are distributed among the following themes:
1. Desertification and global climatic change 2. Biodiversity in mangrove and halophyte ecosystems 3. The effect of wind and water on soil erosion and sand creep 4. Land degradation and management in arid, semi-arid, and dry sub-humid areas 5. Policies and cost/benefits for combating land degradation and desertification 6. Application of remote sensing and Geographic Information System (GIS) to desertification studies 7. Groundwater resources in desert areas
Desertification is land degradation in dry land environments resulting from such factors as climatic variation and human activities. It is the outcome of the interactions between human land-use practices and a dynamic, uncertain environment. If global warming predictions are realized, the environments of desert areas and their margins are likely to be profoundly affected. Global warming may lead to changes in soil moisture availability following changes in both precipitation and evapotranspiration rates caused by the temperature rise itself. The global climate is ever changing, however, global warming does not result in every point on the surface of the earth experiencing an increase in surface temperature. There is a need to study climate on local spatial scales in order to understand its variability in time. This change is an integrated effect of natural climate variability and human-induced changes. Protection and habitat preservation initiatives offer the best solutions for biodiversity conservation in the face of desertification and loss of rangelands to agriculture. Both dryland and wetland reserves have provides effective protection for rare, endangered, and endemic species. Mangroves are one of the dominant features of the shores of tropical countries. Ecologically, they have been considered an important component of coastal ecosystems. Biodiversity and the mangrove ecosystem are closely related to diversity of coastal bio-climatic, geological and sociological conditions; frequency of inundation; circulation pattern; and water quality of coastal areas. Land degradation, desertification, and deforestation are considered to be major environmental problems in many countries of the world. The major causes for desertification were recognized as natural environmental factors and manmade causes. Unsustainable irrigation practices, overgrazing, uncontrolled cultivation, wood-gathering for fuel, salinization, and water logging are cited as the main activities that contribute to the degradation of land area in the region.
The Dubai International Conference on Desertification has focused on an issue that affects most of the world’s population, directly or indirectly. It is of paramount importance in the Middle East, Africa, Asia, Australia, and America and is closely tied to the vicious cycle of poverty and environmental deterioration.
The Zayed International Prize for the Environment fully sponsored and organized this conference. This Prize is a non-profit organization aiming to promote and encourage outstanding and pioneering environmental achieve- ments in line with the environment and development vision and philosophy of the dedicated environmentalist, H.H. Sheikh Zayed Bin Sultan Al Nahyan, President of the United Arab Emirates.
Founded by General H.H. Sheikh Mohamed Bin Rashid Al Maktoum, Crown Prince of Dubai and UAE Defense Minister, the Zayed International Prize for the Environment, is more than a prize – it is a foundation which endeavors to promote sustainable development through various environmental initiatives. In addition to adminis- tering the prestigious Prize of one million dollars, this foundation also organizes regional and international con- ferences and forums on specific environmental issues; publishes a magazine, a book series, and a newsletter; and
Desertification in the Third Millennium. Edited by A.S. Alsharhan, W.W. Wood, A.S. Goudie, A. Fowler and E.M. Abdellatif. © 2003 Swets & Zeitlinger Publishers, Lisse, The Netherlands, ISBN 90 5809 571 1, p. IX–X.
X
helps raise environmental awareness through public lectures, training seminars, workshops, and the development of relevant information materials.
The Zayed Prize for the Environment will be awarded to individuals and organizations that have:
• successfully solved a specific environmental problem; • advanced the cause of the environment toward sustainable development; • brought to public notice significant environmental issues or mobilized action toward their solution; • contributed significantly to intellectual, scientific, or theoretical approaches to environmental concerns; and/or • undertaken activities and initiatives which can serve as a model to others.
For information and submission guide it is recommended to refer to the website: www.zayedprize.org
The Editors A.S. ALSHARHAN, W.W. WOOD, A.S. GOUDIE, A. FOWLER, and E.M. ABDELLATIF
The Dubai International Conference on Desertification was the first international event of the Zayed Prize Foundation. The members of the Organizing and Scientific Committees of the conference express their sincere gratitude and thanks to the General H.H. Sheikh Mohamed Bin Rashid Al Maktoum, Crown Prince of Dubai, UAE Defense Minister, Patron of the Zayed International Prize for the Environment and Patron of the Conference, for his unceasing support and inspiration that made this event a great success.
We would like to thank H.H. Sheikh Nahyan Mubarak Al Nahyan, Minister of Higher Education and Scientific Research and Chancellor of the United Arab Emirates University for his inspiration, encouragement and support.
Special thanks go to the United Arab Emirates University for helping in the organization and follow up, and to the Dubai Police General H.Q. for their unlimited support in terms of facilities and human resources. The Dubai Police sub-committees were very instrumental in making sure that everything ran smoothly and systematically. The UAE Radio & TV Corporation in Dubai did a great job in promoting and covering the conference. The UNDP office in Abu Dhabi was instrumental in distributing the message via the UNDP offices all over the world. The UNEP played a major role in the coordination and opening of the conference together with the UNCCD Secretariat. We also thank the United States Geological Survey for their support of the Scientific Organization Committee.
Sincere appreciation is also extended to all the sponsors who contributed to the conference and/or participated in the exhibition to make it a success; especially the UAE Post, Emirates Airlines, BMW, National Bank of Dubai, DUBAL, Gulf Eternit, Dubai Municipality, Dubai Electricity & Water Authority, UAE Federal Environmental Agency, and the UAE Ministry of Agriculture & Fisheries.
Our sincere appreciation goes to all the authors of this proceeding for their efforts in writing and revising their manuscripts to meet our deadlines and the publisher’s standard.
The authors of this book would like to thank Dr. Mohamed Ahmed Bin Fahad, Chairman of the Higher Committee of the Zayed International Prize for the Environment, for his inspiration and encouragement. Without his support, this publication would not have been possible.
We greatly appreciate the effort of Mr. Mohamed Shahid who assisted us in more ways than could be imagined. He processed the chapters for this volume from inception to final completion, incorporated the authors’changes, and handled all correspondences with the authors. We would also like to express our thanks to Mr. Hamdi Kandil for drafting all the figures, arranging them in proper position in this book, and producing the final camera-ready copy of this volume.
We thank Balkema Publishers for their patience and encouragement from the inception of this book to its completion.
We dedicate this publication to General H.H. Sheikh Mohamed Bin Rashid Al Maktoum, Crown Prince of Dubai, UAE Minister of Defense, and Patron of the Zayed International Prize for the Environment.
Desertification in the Third Millennium. Edited by A.S. Alsharhan, W.W. Wood, A.S. Goudie, A. Fowler and E.M. Abdellatif. © 2003 Swets & Zeitlinger Publishers, Lisse, The Netherlands, ISBN 90 5809 571 1, p. XI.
PART 1
INTRODUCTION
The interactions between people and the environment are, at the beginning of the 21st century, more compli- cated, intense and extensive than ever before (e.g. Babaev, 1999). Land degradation, of which desertification is the component within the world’s drylands, has been suggested to be the most pressing of current environmental problems (Stocking, 1995). Some authorities, such as Williams and Balling (1995), have presented desertification as the outcome of late 20th century population growth, resulting in increased human pressures on marginal dryland environments. The growth in significance of desertification is therefore one of many steps of human pressure on the environment that have occurred and continue to occur during the Holocene period, as both population numbers and the ways in which societies can use the physical environment have increased.
Desertification, even if viewed as a subset of the general land degradation problem, has undoubtedly proved to be controversial, especially in the period since the 1977 United Nations Conference on Desertification (UNCOD) (see Thomas and Middleton, 1994; Stiles, 1995). The term has been seen as confusing, by lumping together a range of environmental processes (e.g. Barraclough, 1995) and because of the images it pres- ents, as misleading, and therefore redundant (e.g. Mainguet, 1991), as it conjures up inappropriate images of desert advance through sand dunes encroaching upon productive land (a process that might occur in a very small number of limited instances, but which certainly is not the universal face of desertification). Even with more appropriate recognition of the insidious nature
of desertification in most instances, an agreed definition, consensus about the scale of the problem and an acceptance of the most appropriate ways to tackle it, have been difficult to achieve. We can however be fairly certain that the term and phenomena are here to stay, particularly as in 1994, after intensive and complex discussions the UN general assembly approved the Convention to Combat Desertification (CCD).
Desertification is therefore a much-discussed environmental, and social, problem, and one that scientists, politicians, non-government organisations (NGOs) and even environmental journalists have held strong views about. The CCD has been ratified both by the governments of “affected country parties”, those countries that experience desertification, and by “developed country parties”. These groups are in theory not mutu- ally exclusive, since developed world countries with dryland areas can be, and are, affected by desertification, for example in the case of European Union states bordering the Mediterranean basin, but this categori- sation does hint towards a polarisation of the states of the North (which can be donors) and the South (which can receive financial assistance under the Convention). November 2002, 184 countries had ratified, accepted to the convention. This includes many countries form the South, including those experiencing desertification, and many countries from the North who are potential sources of expertise and finance for anti- desertification activities. A number of countries that were initially reluctant to recognize the convention, including some with extensive dryland areas, have now done so. Notable in this respect are the USA (ratification in February 2001) and Australia (August 2000).
Into the Third Millennium: The Role of Stakeholder Groups in Reducing Desertification
D.S.G. THOMAS Sheffield Centre for International Drylands Research, Department of Geography, University of Sheffield, Sheffield, UK
ABSTRACT: Desertification, or land degradation in drylands, is the outcome of the interactions between human land-use activities and a dynamic, uncertain environment. Desertification is not a new problem but, since its for- malisation in 1977 at United Nations Conference on Desertification, has been a controversial one. Drawing prin- cipally upon the African desertification context, the paper considers the factors that have contributed to the controversial nature of desertification and the issues associated with four stakeholder groups: politicians, scientists, local people and NGOs, in anti-desertification activities. Each of these groups is given a role within the UN’s 1994 Convention to Combat Desertification, and while all are significant within anti-desertification activities, it is argued that their relative positions have fluctuated in the period since United Nations Conference on Desertification.
Desertification in the Third Millennium. Edited by A.S. Alsharhan, W.W. Wood, A.S. Goudie, A. Fowler and E.M. Abdellatif. © 2003 Swets & Zeitlinger Publishers, Lisse, The Netherlands, ISBN 90 5809 571 1, p. 3–12.
The CCD represents a key stage in the long, tortuous, relationship between the United Nations and desertification. The relationship commenced formally in 1977 with UNCOD, but less formally, UN agencies such as the FAO and UNESCO had been investigating and inter- preting environmental problems in drylands since the 1950s. For example, Meig’s (1953) much-cited definition of arid environments was published in UNESCO’s Arid Zone Research Series. The CCD has been seen as a sustainable development strategy, since it embodies economic, social and environmental needs and issues (Chasek, 1997). The process leading to the drafting of the CCD and its subsequent ratification are well described by Corell (1999), and involved the representatives of national governments, representatives of 187 different NGOS from around the world, and a 17-strong International Panel of Experts on Desertifi- cation (IPED), representing a range of science and social-science disciplines. The negotiation of, and preparation for, the CCD arguably provided avenues for inputs from local (via NGOs) to national levels, and from traditional and “expert” (via IPED) sources. The CCD also recognises the roles of a range of action levels, from international to “bottom-up” in countering the desertification problem.
It is not the purpose of this paper to specifically consider the contributions and relative responsibilities of different groups of actors in the CCD, however; this has been done in detail by Corell (1999). The CCD is just one component of the desertification issue, and its impact and effectiveness are not yet clear. Rather, this paper sets out to provide a qualitative assessment of the relative roles of four key actor groups: politicians, NGOs, local peoples and scientists, in the issues and controversies that have surrounded desertification and in the attempts to counter land degradation in drylands.
DESERTIFICATION CONTROVERSIES
There are a number of reasons that can be identified as sources of the confusion and controversies that have surrounded desertification, especially in the past 20 or so years. Recognising these factors provides a useful background to the consideration of the roles of different groups of people in the desertification debate. Four important factors are considered below.
Issue clarity and images
With over one hundred published definitions (Glantz and Orlovsky, 1983), desertification has been inter- preted as both an environmental process and as a state of the environment. Many of the published definitions
treat desertification as a collective term for environment- degrading processes that are enhanced by both direct and indirect anthropogenic actions. Differences between definitions frequently occur in the detail, for example in terms of whether changes in vegetation systems, which may be readily reversible, are of the same status as changes in the soil system that, once eroded or salinized, may represent an almost permanent negative change of condition (see Thomas and Middleton, 1994 for discussion). These details however have significant implications for how desertification is assessed, monitored and addressed.
In the CCD desertification is defined as land degradation in arid, semiarid and dry subhumid areas resulting from various factors including climatic variation and human activities. In this definition land includes soil, vegetation and groundwater resources. This definition is in fact modified from an earlier UN version (UN, 1992) that stated only human actions as the causal mechanism. The broadening of the definition represents in part a political and scientific compromise (to remove “the blame” solely from human actions, to include “acts of god” for which people, and politicians, cannot be held responsible) and scientific pragmatism (human actions can themselves modify climate, thereby providing an indirect human impact on desertification. While the focus on drylands may seem obvious for an issue called desertification, it has not always been the case, with the term being more widely implied in some quarters, especially in the post UNCOD-period, to include environments far away from dryland areas, for example Denmark (in Fantechi and Margaris, 1986). As Warren and Agnew (1987) note, a broad definition has a tendency to deprive the term of diagnostic value.
The relationship between desertification, which relates to land degradation, and drought, a natural climatic phenomenon, has also lacked clarity. The two issues appear to have been intermingled from the out- set of preparations for UNCOD, since it was the social impacts of the 1970s Sahel drought that triggered demands for an international conference on desertification (Thomas and Middleton, 1994; Corell, 1999). Drought is an intrinsic component of dryland areas (e.g. Agnew and Anderson, 1992), and it is indis- putable that drylands are very susceptible to drought. From a human dimension, drought is something that has to be copied with, or avoided. Nomadism and structured human mobility are drought-coping strategies that have been effected by dryland populations for centuries. Both however are increasingly denied by the sedentary social structures imposed by growing absolute population sizes, and by patterns of land use change and allocation that inhibit of expressly exclude traditional migration patterns (e.g. Sporton et al., 1999). Consequently, dryland populations are perhaps more vulnerable to drought today than at any time in
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the past. Coping with drought however is a different matter to coping with, or reducing, desertification (e.g. Kemp, 1990; Warren and Khogali, 1992), and should not be confused. The former may require relatively short-term aid or external food support, the latter requires a structured, long term effort to halt and then reverse the processes of land degradation.
Lack of scientific understanding about dryland environments
Dryland areas, ranging from dry subhumid regions to the “true” hyperarid deserts, cover 47% of the earth’s land surface (Hulme, 1996; Middleton and Thomas, 1997). The scientific understanding, and knowledge of, dryland environmental systems is relatively poor (Warren et al., 1996) lagging behind the understanding of temperate environments and even of unpopulated polar regions. Many reasons account for this, but two of significance can be noted. First, for some branches of the environmental sciences, description has exceeded explanation in dryland areas (e.g. Cooke and Warren, 1973), depriving science of a structured, analytical basis for understanding the behaviour of the environment. Second, in some fields, scientific paradigms developed in non-dryland environments have been imported to inappropriate dryland situations. This is particularly significant in ecology, where only now is an appropriate understanding of “disequilibrium” ecological systems being achieved (e.g. Behnke et al., 1992). Distinguishing natural vegetation system variability, in response to moisture deficiencies at the seasonal, annual or longer time scales, (e.g. Tucker et al., 1985) is an important aspect of the correct iden- tification of desertification. Both these points are significant to the understanding of desertification and the manner in which dryland systems respond to external disturbances (e.g. Dougill et al., 1999), for in the past misinterpretations of the extent and nature of desertification have arisen from these sources (Thomas and Middleton, 1994).
The timetable of desertification: data bases for effective assessments
The human dimensions of desertification mean that a definition of the problem must have relevance to human needs. The rate of occurrence of the negative changes to the environment associated with desertification is an all-important component of the issue. Abel and Blaikie (1989) defined rangeland degradation as an effectively permanent [their italics] decline in the rate at which the land yields livestock products under a given system of management’ (Abel and Blaikie, 1989,
113). Ten years on, this definition has been para- phrased to apply to soil degradation, which has been defined as “an effectively permanent decline in the rate at which land yields products useful to local livelihoods within a reasonable time-frame” (Scoones and Toulmin, 1999, p. 63). These definitions illustrate an important principle in the determination of desertification, namely that a temporal dimension, relevant to human needs and activities, should be incorporated within consideration of the problem. Slow degradation has little relevance to rural subsistence communities and their production of food to meet immediate needs. Terms such as “soil mining” (e.g. Ramisch, 1999) or even “cattle mining” (e.g. Perkins, 1991), used to describe unsustainable practices, need to be set in an appropriate societal frame- work, as well as an environmental one. But in drylands, assessing the rate of change can be problematic when long term monitoring systems are largely absent and projections of rates of change and degradation are often derived from imprecise data sources (e.g. Stocking, 1996). Where data on regional-scale changes in vegetation cover are becoming available, often through the use of remotely sensed media, they can in some situations be used to show close parallels between desert “expansions” and retreats and rainfall values (e.g. Tucker et al., 1991, Nicholson et al., 1998).
Desire to counter the problem faster than knowledge allows
UNCOD highlighted the desertification problem and set an agenda for its solution. Feasibility studies were presented in 1977 for tackling different forms of desertification (Spooner, 1989). The Plan of Action to Com- bat Desertification that arose from UNCOD set a target for eradicating desertification by the year 2000. This was soon viewed as unfeasible (UNEP, 1981), for a variety of reasons including financial constraints, not only within affected countries of the south but also in terms of the limited contributions that were being made to UNEP’s Special account for anti desertification activities (UNEP, 1982; Thomas and Middleton, 1994). Odingo (1990) has also questioned whether the scientific and technical know-how to act rapidly in effective anti-desertification measures actually existed at the time. The relative level of knowledge about dryland environmental systems compared to that for other environments (see above) suggests that Odingo was correct. Further, issues of whether desertification is an environmental problem, requiring technical solutions, or societal problem, requiring structural and behavioural changes, have real impacts on achieving appropriate trajectories for effectively tackling the problem (see Thomas and Middleton, 1994; Stiles, 1995).
5
STAKEHOLDERS
The preceding summary of issues contributing to the controversies surrounding desertification contains implicitly within it a key characteristic of all environmental issues; namely that there are different groups of “stakeholders” affected by the issue and who have different perspectives on the key aspects of the problems inherent to the issue and relevant to its solution. The contribution, influence and status of these groups has varied in the twenty or so years since UNCOD, though all have been involved to varying degrees throughout. We now turn to consider the significance of the issues linked to these groups to the manner in which the desertification problem is perceived, and acted upon.
The political issue
The high-profile attained by the desertification issue in the late 20th century can be attributed significantly to political processes. Lobbying by political leaders from Sahel countries affected by severe drought in the 1970s specifically led to the establishment of UNCOD (Glantz, 1977), as it was felt (but not universally agreed upon by all developed state governments) that an international strategy was necessary to raise awareness of the problem.
Simplification of the real complexities within an environmental problem may be essential for global debate and discussion to occur (Scoones and Toulmin, 1999). This dumbing-down strategy is not new, as an interesting dryland example illustrates. In the 1940s, when trying to get the US Senate to agree a financial package to help farmers in the US midwest “dust bowl”, which had been affected by soil degradation for several decades, US statesman Dean Acheson is purported to have advised President Truman to “Scare ‘em Harry, or nothing will be done”(R.W Simonson pers. com., 1995).
The globalisation of desertification as an issue was undoubtedly a significant (but not the only) factor in some of the simplistic representations of the issue. As Barraclough (1995: 23) records: “The term [desertification] is much more useful for mobilizing political support to combat what are imagined to be desert sands marching over once-fertile crop lands and productive pastures than for analysing the causes, effects and proposed remedial actions to deal with the multiple processes generating land degradation.” A key purpose of the globalisation of desertification associated with UNCOD was to generate international financial support for anti-desertification actions in developing countries, particularly those with insufficient
resources of their own to do so (Corell, 1999). There is some evidence to suggest that this effect was achieved. In 1986 for example, both US and UK governments were being urged to give financial aid to Sahel countries on the basis of perceptions of the Sahara advancing over adjacent areas at a rate of several kilo- metres per year (Warren and Agnew, 1987, p. 2). The advancing desert image was also prominent in UNEP publicity in the 1980s (see Thomas and Middleton, 1994), and Swift (1996) has suggested that when reli- able data presenting a more complex picture of dryland land degradation began to appear, it was deliberately ignored.
Although some authors (e.g. Stiles, 1995) have offered robust defence of early representations of desertification, it is suggested that this type of “crisis narra- tive” (Scoones and Toulmin, 1999) is ultimately counter-productive, since even if widespread interest in, and recognition of, the problem is engendered, inappropriate and ineffective solutions may be effected. For whatever reason, in the case of desertification a different problem in fact befell the actions planned by the UN Consultancy Group for Desertification Control (DESCON), namely the lack of financial contributions that were forthcoming from developed world nations (Thomas and Middleton, 1994).
As well as being a tool for raising international awareness of an environmental problem, it has been proposed that the spectre of desertification has deflected blame from the real causes of social problems in parts of the Sahel. In an analysis of the causes of food short- ages in parts of the Sudan in 1983–84, Ollson (1993) has suggested that financial and political structures that favoured price rises and discouraged the movement of food stocks available within the country to areas of real need were more significant than land degradation in causing drought-related famine.
Science and desertification
There were significant scientific inputs to UNCOD in 1977, in the form of statements about the nature of desertification and the preparation of case studies illustrating the occurrence and nature of the problem (Thomas and Middleton, 1984). Scientific inputs to the preparation of the CCD, through the International Panel of Experts on Desertification (IPED) have been assessed by Corell (1999), and identified as lesser in scale and having a more limited impact than in the case of UNCOD.
The role of science in the desertification debate has previously been considered by Thomas (1997). In the period since UNCOD, systematic scientific research into components of environmental systems pertinent to desertification has grown considerably, with notable
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advances occurring in many areas of dryland environmental knowledge (Table 1). Improvements have also occurred within the understanding of a range of environmental processes in drylands including salinization (e.g. Rhoades, 1990), soil nutrient movements (e.g. Scholes and Scholes, 1989; Tolsma et al., 1987), rangeland ecology (e.g. Walker and Noy-Meir, 1982), vegetation responses to stress (e.g. Behnke et al., 1992), and the operation of aeolian processes, including in relation to vegetation cover change (e.g. Wiggs et al., 1995). Remote sensing studies have also contributed to better understandings of both the temporal (season to season, year to year, and decade to decade) and spatial patterns of flux that operate within components of dryland environmental systems.
It may therefore seem perverse that scientific contributions to the development of the CCD were limited, since science would appear to have had more to offer in the 1990s than it did two decades earlier. Closer consideration however suggests that this may be the very reason for the lesser role; On the one hand, the CCD needed the authority of a scientific group to legitimise its negotiations, but on the other hand a more central involvement would have emphasised the uncertainties surrounding the phenomena of desertification, thereby reducing the likelihood of an agreed convention being achieved (Corell, 1999, p. 201).
Despite the advances in the scientific understanding of dryland systems that has occurred in recent decades, the pace of science and the nature of scientific research are not necessarily well attuned to the needs of others involved in the quest to understand and resolve desertification, especially those who seek rapid solutions to the problem. Bo Kellen, Swedish diplomat and chair of the negotiations leading to the CCD, is reported to have noted in 1993 that “Scientific controversies are irrelevant to people facing famine” (Thomas, 1997). An alternative view is that scientific advances have led to the orthodoxies of desertification been questioned,
so that far from being irrelevant, science has in fact contributed to a more realistic view of the complexities of drylands and of the land degradation that can occur within them.
Societies directly affected by desertification
People affected by desertification, especially those in rural areas of developing countries, have sometimes been presented as passive victims of the problem (e.g. in statements such as “the future of 900,000,000 people at risk” (e.g. UNEP, 1991) or as the root cause of degradation (see Thomas and Middleton, 1994). Similarly, poverty has been viewed as a major cause of desertification, causing people to adopt unsustainable practices for short term gains, or as an outcome of desertification, resulting from less productive agriculture as lands become desertified. Neither view is very helpful (see, e.g. Barraclough, 1995), and both have been challenged, through the outcomes of social science research and through greater representation of community views in negotiations leading to the CCD (see below).
Traditional pastoral societies have in particular been viewed, by outsiders looking in, as irrational in their use of shared natural resources and in their attitudes to livestock numbers and the environment. This general- isation has been challenged (e.g. Livingstone, 1977; Mace, 1991) in social science research that has in many ways paralleled the revised understanding of the behaviour of dryland ecological systems. This has been achieved in the last ten years or so, since it was noted by Spooner (1989) that environmental and social scientists were largely ignoring each others efforts and interpretations, yet both were vital for a sensible understanding of desertification.
As well as being those directly affected by desertification, local people are the group of actors through
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Table 1 Some scientific advances in1980s onwards, relevant to desertification issues.
Scientific research has led to an awareness that: 1. Dryland environments are characterised by significant temporal and spatial variability in key system components,
e.g. rainfall (see Hulme, 1992) and natural vegetation systems (see e.g. Warren, 1995 for a summary and discussion). 2. Drought is a natural dynamic component of dryland rainfall systems (and subsequently awareness that many
indigenous NR systems are/were adapted to this). 3. The concept of climax vegetation systems is not appropriate to most dryland settings, and that many ecological
systems display disequilibrium characteristics (and subsequently that NR management systems which attempt stable, constant, off take levels are thus not likely to be successful).
4. The soil resources of many drylands are nutrient poor and in some cases are closely coupled to vegetation systems (e.g. Dougill et al., 1999).
5. Natural environmental variability has to be accounted for in assessments of dryland change and degradation. 6. Feedbacks may occur between ecosystem changes are lower atmosphere processes, potentially resulting in the
enhancement of desertification. 7. The lack of spatial and temporal homogeneity in dryland systems makes the scaling up of data from small scale
studies inappropriate (Stocking, 1996), and also frequently makes prescriptive solutions to desertification inappropriate.
which the environmental and social dimensions of the problem meet, interact, and generate an outcome (e.g. Thomas and Sporton, 1997). When traditional societies do conduct actions that lead to degradation, it is now more common to view this as a function of their livelihoods and life styles being compromised by structural and political changes in the 20th century (e.g. Kipuri, 1995) that lead to a departure from practices that embody good land husbandary. Noting the history dimension to perceptions of local people as the cause of degradation, it has been written that facile generalizations are always plagued by multiple excep- tions…explanations of desertification assuming peasant ignorance and shortsighteness were especially in vogue with colonial administrators. These have been largely discredited by research illuminating traditional peasant farming and social systems and the processes disrupting them such as land alienation, surplus extraction and commercialisation. (Barraclough, 1995, p. 33).
Research by Mortimore (1987) in Nigeria identified a ranch of traditional “insurance strategies” against times of environmental stress resulting, for example, from drought. Where external changes result in the adaptation of practices that contribute to land degradation, these may prove to be transitional and not permanent (Stocking, 1996). For example, Tiffen et al. (1994) have shown how slopes in the Machakos District of Kenya that showed signs of severe soil erosion in the 1930s have in fact be turned into highly productive cropping systems, due to a change in land tenure arrangements and the replace- ment of colonially instigated livestock production systems with indigenous market-driven cultivation. Whether or not land degradation is actually taking place may also differ according to the circumstances of the observer. The erosion of soil from steep slopes, which may appear to represent significant land degradation by some, may in fact be viewed as beneficial by local land-users if it replenishes soil fertility in flatter valley bottoms that are more readily accessed for production (e.g. Scoones, 1992).
The recognition that people affected by desertification are not necessarily the direct cause of the problem, that there are a wide range of complex socio-environmental interactions that are mediated by externally-derived structural frameworks, and that these very people may in fact hold the vital keys to successful degradation mitigation, are views that have now permeated considerations of the most successful ways to combat desertification and land degradation.
It is however important that one set of generalisations about desertification, including those that include generalised views about local peoples, are not replaced by another. In many parts of Africa, land tenure systems are dynamic, and continually evolving
(Thebaud, 1995). The relationships between different groups within rural populations may be complex (e.g. Hagmann and Murwira, 1996; Sithole, 1995), while population movements and displacements due to factors including conflicts (Hendrickson et al., 1998), land tenure and ownership changes brought about by national policies (e.g. Sporton et al., 1999) and the quest for greater incomes in urban areas (e.g. Millington et al., 1989) are amongst the factors that may in practice make direct routes to locally-based anti-desertification activities less than simple to implement.
Non-Government Organisations
Non-Government Organisations participated widely in the processes contributing to the CCD, such that it is necessary to consider them as a further important stakeholder-group in desertification. The term NGO is in itself a catch-all that embraces a wide range of groups, some scientific, some political, some lobby groups and some more concerned with aid-related activities, including the dispersal of funds sourced in central governments. Conflicts may even exist between the aims and purposes of specific NGOs involved in the same environmental issue. The role of NGOs within the desertification convention process included lobbying for particular interests, providing information and knowledge and, of particular importance, acting as agents of social change (Corell, 1999). About 50% of NGOs involved in the CCD negotiations came from Africa, and these contributed in particular to reinforcing the need for the incorporation of local and indigenous knowledge and for “bottom-up” action in future plans to combat desertification.
How an international initiative such as the CCD can effect successful bottom-up actions may in fact lie in the hands of the NGOs, especially those working at grassroots level that may be in a position to integrate local-population based factors and actions into the components of the international agreement that have a local bearing. NGOs themselves are aware of the potential difficulties in effecting a useful role in implementing the CCD, and these have been reflected within their own international desertification network – RIOD (Reseau International d’ONG sur la Desertification). It has for example been noted that to date the most effective NGO interventions in environmental problems have been in terms of addressing short term problems (for example, drought impacts), including working within existing national policy frameworks. Action in the context of the CCD will require sustained actions and also may generate needs to challenge existing policy frameworks in some affected countries. In India for example, it has been
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noted that many NGOs only have local spheres of influence which may render them relatively ineffective in situations where national changes of policy may be required (Kohler-Rollefson, 1995). In other situations competition between NGOs has led to a lack of con- certed effort against national policies that may enhance environmental degradation.
Discussion: global, national or local ?
In practical terms, bridging the global-to-local gulf is critical in debates about the effective assessment of, and establishment of solutions to, desertification. On the one hand, to receive prominence amongst the plethora of big environmental themes, action against desertification needs global co-ordination, at the very least to give the matter a global presence. The global dimension is also relevant since money to finance self help and remedial actions, especially in the developing world is needed, and the CCD cannot afford to suffer the same financial setbacks and shortfalls of earlier internationally co-ordinated efforts. On the other hand, several of the major controversies surrounding desertification can be traced to its global dimension, notably questions of whether desertification is actually a myth (Binns, 1990; Swift, 1996), and whether the extent of the problem has been exaggerated (e.g. Thomas and Middleton, 1994). In a report on African soul fertility management, prepared for the UK Depart- ment for International Development, Scoones and Toulmin (1999) have recently summarised the scale issue and its importance: “Global initiatives such as the CCD, and the [World Bank-co-ordinated] Soil Fertility Initiative provide a means for getting attention paid to formerly neglected areas and themes. However the very simplicity of the
message they present … provides a misleading and potentially damaging assessment of what is happening.”
There does indeed appear to have been a crisis of confidence in intervention in desertification at the institutional level (Warren, 1995). This may have been influenced by a range of factors, many derived from scientific developments and the appreciation of the rightful role of local actions in tackling land degradation (Table 2). Now small is beautiful, variability and variety are seen as more relevant than generalisations, and bottom-up actions as more likely to be successful than those applied at higher levels. But the two levels should not necessarily be instantly divorced, for if community action and indigenous knowledge are given greater weight and opportunity as a result of the CCD, it should not be automatically assumed that the impacts of desertification would be mediated against successfully.
Community actions, and the ability to apply local knowledge, will still have to operate within whatever national and international frameworks influence the potential opportunities (e.g. Sithole, 1995). Because it is now fully accepted that: “Dryland degradation (desertification) does not involve moving sand dunes, Rather, it concerns the gradual impoverishment of agricultural and pastoral systems, which makes them less productive and more vulnerable to drought (Toulmin, 1995, p. 5); then it is also implicitly agreed that the problem is a complex one, with solutions that are equally complex, specific and in need of involving the participation of those who bear local knowledge and are most likely to benefit from successful outcomes. The recognition of this was largely achieved through the realisation, including amongst politicians, that a generalist approach was not working; through advances made in environmental and social science research that contributed to a clearer understanding of the complexities of drylands, and
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Table 2 Factors contributing to changing perceptions of desertification, its causes and solutions.
a) Lack of materialisation of funds in UNEP’s Special Account, thus prohibiting significant UN-derived top-down action; b) Top-down projects, funded by e.g. the World Bank and donor North governments, proving expensive and lacking the
support and interest of directly affected local peoples (e.g. see Zaal et al., 1998); c) Improved research-derived understanding of the nature and dynamics of dryland environments including awareness of
significant temporal and spatial variability (e.g. Hulme, 1992; Thomas 1993; Warren 1995) and the inapplicability of environmental paradigms directly transferred from temperate environments (e.g. Behnke et al., 1992);
d) Equivalent challenges to accepted (western derived) orthodoxies about people-environment relationships (especially in Africa: e.g. Leach and Mearns, 1996), including the use of open access systems that had previously been seen as disorganised by western eyes (Woodhouse, 1997);
e) Awareness of the richness of local peoples’ knowledge and experience of their environments, and their resourcefulness in the face of difficulties (e.g. Adams, 1996; Scoones et al., 1996; Deme, 1998);
f) Awareness of the complex milieu of social, political and economic circumstances affecting local peoples behaviour and relationships with the environment and natural resources, including interactions between livelihoods, poverty/wealth levels and structural changes associated with post-colonial changes in African countries (see e.g. Barraclough, 1995);
g) Awareness of the holistic nature of many environmental problems: the realisation of links between different environmental issues world-wide and social-environmental issues in Africa (e.g. Cardy, 1997; Squires and Glen, 1997), resulting in benefits being ascribed to multi-pronged and multi-directional approaches, analyses and solutions.
through a greater voice being given, at least in part due to the role of NGOs, to the views, concerns and knowledge of local people in affected areas.”
National Action Programmes are a cornerstone of the CCD, but unlike the National Plans of Action prepared after UNCOD, which tended to be top-down and rather general in approach (Thomas and Middleton 1994), the NAPs being produced under the CCD have a greater emphasis of participatory activities involving local communities and practical actions that can be taken to redress and inhibit land degradation. Recognising however that desertification is not solely confined within national boundaries, Regional and Sub-regional Action Programmes are also encouraged within the CCD, not as an up-scaling exercise but as one that that allows for the integration of good practices and the mutuality of approaches appropriate within geographic regions.
Just as local action is necessary within actual anti- desertification actions, so science retains an important role too. This includes retaining issue clarity, desertification monitoring, identifying appropriate scales of action in specific spheres of degradation and identifying characteristics of environmental system recovery and the relationships between this and human actions (Thomas, 1997), as well maintaining a watching brief on the interactions between desertification and other major environmental issues such as global warming and biodiversity loss (Cardy, 1997). The CCD includes the need for the establishment of the Committee of Science and Technology, to play a number of roles relating to anti-desertification measures. The CST is not however a global-level “elite” but has a role to co-ordinate, assimilate and disseminate the beneficial information gained from local knowledge and expertise, in a manner that links science with local action (e.g. van Rooyen, 1998). The overall CCD includes within it obligations for the countries that are party to it, including the need to work towards eliminating poverty and recognising the roles of local peoples and NGOs in efforts to eliminate desertification. While, in the 20- odd years since UNCOD, the balance of importance attached to the different groups of players in the desertification issue, politicians, scientists and local people are all critical parties if desertification is to be successfully managed and reduced.
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INTRODUCTION
Even though arid lands cover a third of the earth’s land surface and are already subject to severe land degradation (desertification) pressures, remarkably little thought has been given to what might happen to arid lands as a result of any potential warming associated with the enhanced greenhouse effect. Indeed, those sections of the reports of the Intergovernmental Panel on Climate Change that deal with deserts are notable for being narrow and for neglecting almost all the most important issues (Bullock and Le Houérou, 1996; Noble and Gitay, 1996). Some of the regional studies are no more satisfactory, and the one on Africa contains one paragraph only on deserts and concludes with the following debatable remark (Zinyowera et al., 1998, p. 43):
“Extreme desert systems already experience wide fluctuations in rainfall and are adapted to coping with sequences of extreme conditions. Initial changes associated with climate change are less likely to create conditions significantly outside present ranges of tol- erance; desert biota show very specialized adaptations to aridity and heat, such as obtaining their moisture from fog or dew.”
The reality is that arid environments often appear to have been prone to rapid geomorphological and hydrological changes in response to apparently modest climatic stimuli, switching speedily from one state to another when a particular threshold is reached (Goudie, 1994). River systems are prone to episodes of cut and fill; alluvial fans accrete and trench; colluvial aprons show complex sequences of deposition, stability and incision; drainage density and rates of erosion can change very rapidly either side of a critical level of vegetation cover; terminal lake basins expand and contract and freshen and salinate; dust storm activity shows marked shifts in response to runs of dry years and/or increasing land use pressures; and sand seas
appear to have been prone to repeated fluctuations in deposition and stabilisation. This apparent instability and threshold-dependence of a range of desert phenomena leads us to believe that such areas may be especially susceptible to the effects of potential global warming caused by the enhanced greenhouse effect (Figure 1).
Wind erosion of soils
Changes in climate could affect wind erosion either through their impact on erosivity or through their effect on erodibility.
Erosivity is controlled by a range of wind variables including velocity, frequency, duration, magnitude, shear and turbulence. Such wind characteristics vary over a whole range of time-scales from seconds to mil- lennia. For example, Bullard et al. (1996) have shown how dune activity varies in the SW Kalahari in response to decadal scale variability in wind velocity, while over a longer time-scale there is evidence that trade-wind velocities may have been elevated during the Pleistocene glacials (Rea, 1994). Unfortunately, Gen- eral Circulation Models as yet give little indication of how wind characteristics might be modified in a warmer world, so that prediction of future changes in wind erosivity is problematic.
Erodibility is largely controlled by vegetation cover and surface type, and both of these can be influenced markedly by climatic conditions. In general, vegetation cover, which serves to protect the ground surface and to modify the wind regime, decreases as conditions become more arid. Likewise climate affects the nature of surface materials by controlling their moisture content, the nature and amount of clay mineral content (cohesiveness) and organic levels. Soils that are dry have low clay content and little binding humus are highly susceptible to wind erosion.
The Impacts of Global Warming on the Geomorphology of Arid Lands
A.S. GOUDIE School of Geography and the Environment, University of Oxford, Oxford, UK
ABSTRACT: Deserts may change significantly in response to global warming. Modest climatic stimuli may cause vegetation, hydrology and geomorphology to switch speedily from one state to another. Changes in vegetation cover, associated with a decline in soil moisture availability, will increase the risk of soil erosion by wind, may accelerate dust storm activity and cause sand dunes to be reactivated. Large changes in runoff will also occur, leading to marked changes in the nature of river channels. Closed depressions are also sensitive to climate change, and so lake levels may be greatly altered. Finally, arid coastlines will be subjected to sea level change that will lead to transformations in the nature of such environments as deltas, estuaries and sabkhas.
Desertification in the Third Millennium. Edited by A.S. Alsharhan, W.W. Wood, A.S. Goudie, A. Fowler and E.M. Abdellatif. © 2003 Swets & Zeitlinger Publishers, Lisse, The Netherlands, ISBN 90 5809 571 1, p.13–20.
However, modelling the response of wind erosion to climatic variables on agricultural land is vastly complex, not least because of the variability of soil characteristics, topographic variation, the state of plant growth and residue decomposition, and the existence of wind breaks. To this needs to be added the temporal variability of aeolian processes and moisture conditions and the effects of different land management practices (Leys, 1999), which may themselves change with climate change.
Dust storm activity
The changes in temperature and precipitation conditions that occurred in the twentieth century (combined with land cover changes) had an influence on the development of dust storms (Goudie and Middleton, 1992). These are events in which visibility is reduced to less than one kilometre as a result of particulate matter, such as valuable topsoil, being entrained by wind. This is a process that is most likely to happen when there are high winds and large soil-moisture deficits. Prob- ably the greatest incidence of dust storms occurs when climatic conditions and human pressures combine to make surfaces susceptible to wind attack.
Possibly the most famous case of soil erosion by deflation was the Dust Bowl of the 1930s in the USA. In part this was caused by a series of hot, dry years which depleted the vegetation cover and made the soils dry enough to be susceptible to wind erosion, but the effects of this drought were gravely exacerbated by years of over-grazing and unsatisfactory farming techniques.
Attempts to relate past dust storm frequencies to simple climatic parameters or antecedent moisture conditions have frequently demonstrated rather weak relationships (Bach et al., 1996), confirming the view that complex combinations of processes control dust emissions. Nevertheless, evidence is now emerging that relates dust emissions from Africa to changes in the North Atlantic oscillation (Moulin et al., 1997).
If, however, soil moisture levels decline as a result of changes in precipitation and/or temperature, there is the possibility that dust storm activity could increase in a warmer world. A comparison between the Dust Bowl years of the 1930s and model prediction of precipitation and temperature for the Great Plains of Kansas and Nebraska indicates that conditions could be similar to those of the 1930s under enhanced greenhouse conditions (Smith and Tirpak, 1990), or even worse (Rosenzweig and Hillel, 1993).
If dust storm activity were to increase as a response to global warming it is possible that this could have a feedback effect on precipitation that would lead to further decreases in soil moisture (Tegen et al., 1996; Miller and Tegan, 1998). However, the impact and occurrence of dust storms will depend a great deal on land management practices, and recent decreases in dust storm activity in North Dakota have resulted from conservation measures (Todhunter and Cihacek, 1999).
Sand dunes
Sand dunes, because of the crucial relationships between vegetation cover and sand movement, are highly susceptible to the effects of changes of climate.
A.S. GOUDIE
Plant physiological
response Temperature
beach retreat
Sediment movement
Figure 1 Some hydrological and geomorphological consequences of the enhanced greenhouse effect in drylands.
Some areas, such as the south west Kalahari (Stokes et al., 1997) or portions of the High Plains of the USA (Gaylord, 1990) may have been especially prone to the effects of changes in precipitation and/or wind velocity because of their location in climatic zones that are close to a climatic threshold between dune stability and activity.
One of the more remarkable discoveries of recent years, brought about by the explosive development in the use of thermoluminescent and optical dating of sand grains and studies of explorers’ accounts (Muhs and Holliday, 1995), is the realisation that such marginal dune fields have undergone repeated phases of change at decadal and century time-scales in response to extended drought events during the course of the Holocene. Dates for reaction phases are given for the Nebraskan Sandhills by Stokes and Swinehart (1997) and Muhs et al. (1997), for Kansas by Arbogast (1996), and for the South West Kalahari by Thomas et al. (1997).
The mobility of desert dunes (M) is directly proportional to the sand-moving power of the wind, but indirectly proportional to their vegetation cover (Lancaster, 1995, p. 238). An index of the wind’s sand-moving power is given by the percentage of the time (W) the wind blows above the threshold velocity (4.5 m S1) for sand transport. Vegetation cover is a function of the ratio between annual rainfall (P) and potential evapotranspiration (PE). Thus,
M W/(P/PE)
Empirical observations in the USA and southern Africa indicate that dunes are completely stabili

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