Agricultural and Forest Meteorology 101 (2000) 291–292
Book review
Modeling the impact of climate change on rice pro-duction in Asia. Robin B. Mathews, Martin J. Kropff, Dominique Bachelet and H.H. Van Laar (Eds.), Pub-lished by CAB International in association with the International Rice Research Institute, 1995. pp. 289.
The media furor and public and scientific debate over the possibility of future climate change will likely continue until atmospheric scientists gain better mechanistic understanding of the forces that shape our climate and implement substantial improvements in currently used general circulation models (GCMs). Crop simulation modeling is also an evolving science that is not without its detractors. Crop models have gained more acceptance in recent years as these mod-els have been improved and their utility demonstrated in an increasingly wide range of applications. The leveling-off or plateau in rice grain yields experienced in many Asian countries in recent years coupled with a rapidly expanding human population there provides ample incentive to examine potential future climate change effects on rice productivity in Asia with the tools currently at hand.
The authors focus their study on the major rice producing countries in South and East Asia span-ning a geographic range from roughly India to Japan. Much of this book details simulation studies using two different rice crop models to predict potential rice yields at regional scales. These two models dif-fer in complexity with the simpler of the two using a radiation-use-efficiency approach to arrive at final yield. The more detailed rice model utilizes a mate-rials balance approach and explicitly simulates crop physiological processes including photosynthesis and respiration. Since both of these crop models predict potential or maximum rice yield for a given climate scenario, stresses caused by drought, nutrient deficien-cies, insects, diseases, etc. are ignored and the
simula-tions are mainly concerned with the interactive effects of atmospheric carbon dioxide concentration and air temperature on potential rice grain yield. The yield predictions by these two models are in line with my own experimental work on rice with carbon dioxide enrichment enhancing photosynthesis, growth and fi-nal grain yield while high temperatures, especially high temperatures at flowering, reduce yield. Because the current rise in atmospheric carbon dioxide is the best documented feature of climate change, results of these simulations provide valuable insight into possi-ble future rice yields in Asia as well as providing a few surprises. Most notable of these unexpected find-ings was that, in general, the greatest yield increases were predicted for the tropical countries near the equa-tor and some decreases in yield for the more tem-perate countries of South Korea and Japan. On the surface, this result appears counter-intuitive and con-trasts with a similar previous study but the authors provide quite reasonable physiological explanation for how this could occur.
A short coming of these simulations is that planting dates were not optimized in any of the climate sce-narios. Faced with a changing climate, farmers will almost certainly adjust planting dates for a variety of reasons. For example, planting date could be altered to take advantage of an earlier spring or farmers may se-lect a planting date that avoids temperature stresses at critical growth stages. To their credit, the authors ac-knowledge this problem and do provide a couple of in-teresting examples that illustrate the relative trade-offs involved in optimizing planting dates. In their section discussing mitigation options, the authors make ex-cellent use of their models to point out the benefits of breeding rice cultivars with increased tolerance to high temperature. On the other hand, the authors say nothing about the potential for selecting or breeding
292 Book review / Agricultural and Forest Meteorology 101 (2000) 291–292
rice cultivars for greater response to elevated carbon dioxide.
The writing style varies from chapter to chapter due to the involvement of different authors, but in general, the book is well written. The chapter describing the generation of the various climate change scenarios is written in fair and even-handed fashion and the authors take a critical look at the problems associated with the use of the three GCMs in this study. The two chapters describing the rice models are well done and should prove to be of interest to rice physiologists and crop modelers alike. The final summary provides
a good overview of the main findings of the book as well as a discussion of the underlying assumptions and limitations of the models used. This book should be of interest to a wide audience including rice agronomists and breeders, crop modelers and those concerned with world food security issues.
