Modelling the impacts of climate change and methane emission reductions on rice production: a review

Rice agriculture is not only affected by climate change, but also contributes to global warming through the release of methane into the atmosphere. In 1989, a major research project was initiated at the International Rice Research Institute in the Philippines to investigate relationships between climate change and rice production. A second project started in 1993 to investigate, in more detail, mitigation options that could be employed to help reduce CH4 emissions from rice cultivation. An important component of all of this work was the quantification of these interactions between climate change and rice production into simulation models, and their subsequent use to upscale field measurements to national and regional levels. The first project developed such a model to integrate existing knowledge of effects of increased levels of CO2 and temperature on rice growth, and used this to predict the impact of various climate change scenarios on rice production in SE Asia. In the second project, routines describing the dynamics of CH4 production and emission from the soil were linked to a crop simulation model to estimate the effect of different crop management scenarios on national CH4 emissions from various countries in the region. With the recent completion of the second project, it is timely to review this modelling work describing the relationships between the global environment and rice production, a task which we attempt in the present paper. The advantages and disadvantages of the modelling approaches used and other issues relating to the upscaling of field measurements to national and regional levels are discussed. Future research directions in this area are also identified.