Global climate change and agricultural production. Direct and indirect effects of changing hydrological, pedological and plant physiological processes

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Copyright © 1996 by FAO, Rome, Italy

Published 1996 by

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Edited by

Fakhri Bazzaz
Harvard University, USA


Wim Sombroek
F.A.O., Italy

This book reports on the results of experiments to assess the effects of global climate change on the agricultural production of crops and livestock. It covers issues such as the CO2 fertilization effect, the adverse effects of elevated levels of UV-B radiation and ozone on plant growth and productivity, and livestock. Combined effects are also studied, including changing CO2, temperature, and UV-B radiation and O3 simultaneously on crop growth.

The concluding chapters give an idea of the overall global picture in terms of the effects already discussed. Changes in the world hydrological cycle, the regional availability of water resources, changes in soil conditions and the impact of this on food production, as well as modelling techniques, are all examined.

Library of Congress Cataloging-in-Publication Data

Global climate change and agricultural production: direct and indirect effects of changing hydrological soil and plant physiological processes/edited by Fakhri Bazzaz, Wim Sombroek. p. cm.

Includes bibliographical references and index. ISBN 0-471-95763-1

1. Climatic changes. 2. Agriculture. 3. Crops and climate. 4. Meteorology, Agricultural. I. Bazzaz, F. A. (Fakhri A.) II. Sombroek, Wim G. III. Food and Agriculture Organization of the United Nations. S600.7.C54G58 1996

338.1'4 - dc20 96-19503 CIP

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 0-471-95763-1 (cloth)
ISBN 0-471-96927-3 (paper)

Produced from camera-ready-copy supplied by the editors

Printed and bound in Great Britain by Bookcraft (Bath) Ltd

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This electronic document has been scanned using optical character recognition (OCR) software and careful manual recorrection. Even if the quality of digitalisation is high, the FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.

Table of Contents

List of contributors

Preface and acknowledgements

1. The climate change - Agriculture conundrum

The world agricultural context
The changing agricultural environment
Plant physiological direct effects
The hydrological cycle and soils

2. The effects of changes in the world hydrological cycle on availability of water resources

Methods of evaluation
General circulation models
Hydrological models
Recent changes in global precipitation
Recent changes in global runoff

3. The effects of global change on soil conditions in relation to plant growth and food production

Possible changes in forcing variables
Effects of higher CO2 on soil fertility, physical conditions and productivity
Effects of rainfall and temperature changes in different climates
Processes in soils
Some properties of clay surfaces
Resilience against physical and chemical soil degradation
Resilience against soil reduction (anoxic conditions)
Soil reaction (pH)
Effects of a rising sea level on soils in coastal areas

4. The CO2 fertilization effect: higher carbohydrate production and retention as biomass and seed yield

Overview of CO2 effects on plant growth processes
Specific responses of crops to elevated CO2
Summary of comprehensive reviews
Crop modelling: Predictions for the future
Summary and conclusions

5. The effects of elevated CO2 and temperature change on transpiration and crop water use

Water use and water-use efficiency
Response at the level of stomata
Effects at the level of the leaf
Effects at the plant and canopy level
Effects over the growing season
Effects on the regional vegetation-atmosphere water vapour exchange
Concluding remarks

6. Effects of higher day and night temperatures on growth and yields of some crop plants

Mechanisms for heat tolerance
Crop growth and development
Extreme temperature effects on crops
Long-term effects of high temperatures on crops

7. Adverse effects of elevated levels of ultraviolet (UV)-B radiation and ozone (O3) on grop growth and productivity

Effects of elevated surface-level UV-B radiation or O3 on crops
Effects of elevated UV-B radiation or O3 on the incidence of crop pests
Effects of elevated UV-B radiation or O3 on crop-weed competition
Considerations relevant to the study of crop responses to elevated levels of UV-B radiation and O3
Conclusions and future research directions

8. Combined effects of changing CO2 temperature, UV-B radiation and O3 on crop growth

Carbon dioxide
CO2 and temperature
CO2 and water availability
CO2 and ozone
CO2 and UV-B radiation
Ozone and temperature
Ozone and water availability
Ozone and UV-B radiation
Concluding remarks

9. The potential effects of climate change on world food production and security

Study methods
Crop models and yield simulations
Modelling the world food system
An assessment of the world food system under alternative scenarios

10. Climate change, global agriculture and regional vulnerability

Impact assessment methodologies
Crops response estimates for different regions of the world
Global studies and their implications for regional effects
Regional vulnerability
Adaptation potential and policies
The technological potential to adapt
The socio-economic capability to adapt

11. Integrating land-use change and evaluating feedbacks in global change models: The IMAGE 2 approach

Importance of feedbacks and linkages
Model approaches
Concluding remarks

12. Global change impacts on agriculture, forestry and soils: The programme of the global change and terrestrial ecosystems core project of IGBP

Overview of the GCTE and focus 3 structures
Effects of global change on major food crops (a component of activity 3.1)
Improved pastures and rangelands (a component of activity 3.1)
Effects of global change on multi-species cropping systems (activity 3.4)
Experimental studies on the relationship between plant-based diversity and complexity and system sustainability (task 3.4.1)
Modelling complex agricultural systems (task 3.4.2)
Long-term agricultural experiments and databases as a resource for global change research (task 3.4.3)
Effects of global change on managed forests (activity 3.5)
Changes in pests, diseases and weeds (activity 3.2)
Effects of global change on soils (activity 3.3)

13. Global climatic change and agricultural production: An assessment of current knowledge and critical gaps

Present knowledge, problems and uncertainties
Implications and needs