Introduction

Rice provides a substantial portion of the dietary requirements of nearly 1.6 billion people, with another 400 million relying on rice for one-quarter to one-half of their diet (Swaminathan, 1984). In order to keep pace with a rapidly increasing world population, global rice production levels seen in 1991 will need to increase by at least 46% by the year 2025 (IRRI, 1993; Fig. 5.1). This challenge has spurred researchers to seek innovative technologies to overcome the now common levelling off and even reduced rice yields seen in recent years in some areas of the world (Hossain, 1998). Potential future climate change resulting from increased atmospheric carbon dioxide concentration ([CO2]) and other greenhouse gasses (Hansen et at, 1984) further hampers our ability to predict global rice production and raises serious questions concerning food security for the near future. Accurate prediction of the impacts of climate change on rice productivity on a region-by-region basis is essential, not only for the estimation of world food security, but also for the continued sustainability of rice-farming societies, which in most countries consist of small hectarage subsistence farmers.

Several recent simulation studies have estimated the effects of global climate change on regional rice production using different climate change scenarios (Horie, 1993; Horie et at., 1995b; Matthews et at., 1995; Singh and Padilla, 1995). These studies predict that global climate change may have substantial positive or negative impacts on rice production, depending on the region of the world under consideration. However, these modelling studies point to the need for further research in order to test and improve our understanding of environmental effects on rice development, growth and yield. More specifically, research is needed to quantify further the interactive effects of [CO2], air temperature and other environmental variables on rice growth and yield formation processes.

┬ęCAB International 2000. Climate Change and Global Crop Productivity

1950 1960 1970 1980 1990 2000 2010 2020 2030

Year

Fig. 5.1. Actual and projected trends in world population, rice production and yield during the period from 1950 to 2025. (Adapted from IRRI, 1993 and FAO, 1995.)

1950 1960 1970 1980 1990 2000 2010 2020 2030

Year

Fig. 5.1. Actual and projected trends in world population, rice production and yield during the period from 1950 to 2025. (Adapted from IRRI, 1993 and FAO, 1995.)

The objectives of this chapter are to summarize recent research findings on the effects of [CO2], air temperature and other environmental variables on rice growth and yield. It then evaluates the current state of rice/climate simulation models with the intent of defining future research needs in both experimental and modelling studies.

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