Assessing Rice Productivity and Adaptation Strategies for the Indochina Peninsula Under Climate Change Using the Regional Rice Model.

Crop model is the widely used tool to assess the impacts of climate change on crop yield. For most of the field based crop models, the working spatial scale is smaller than the spatial scale of the climate model output. Recognising their limitations, the general large-area model for annual crops (GLAM) was particularly developed to simulate crop yields directly at a regional level. The model has been used to predict wheat yield over China and simulate groundnut yield over large areas in India. In order to simulate the impact of climate change on rice yield, the GLAM-rice (the Generally Large Area Module for annual crops) model has been developed by modifying the crop-specific parameters and some specific growth and development processes. It provided a useful method to assess the impact of climate change on rice yield directly at the regional level.

The regional impact assessments are pre-requirement for selecting of adaptation methods and decision making at the subnational, national and regional level. In order to assess the impact of climate change on rice yield in the Indochina peninsula region, the GLAM-rice was forced with the climate variables from CORDEX-East Asia. The future climate impact on rice varies among countries, and it is dependent on the current climate conditions and the projected climate under future climate. Climate change alone would lead to 3.5-23.2% and 5.8-27.2% reduction in rice yield for 2020s and 2040s with the largest decreases in Cambodia. The negative impacts of climate change can be partly offset by the positive effect of CO2 fertilization. For the countries in the Indochina peninsula, changes in rice yield are quite sensitive to an increase in temperature. The uncertainty in projected temperature from climate model is the main source of uncertainty in impact assessment. So improving the accuracy of projected temperature and reducing the uncertainty in projected temperature are the future effort to reduce the uncertainty. In this study, adaptation strategies, including changes in planting dates and use of irrigation and heat tolerance varieties, were tested. Use tolerance varieties and planting data are simple of management responses, and may offset small part of the negative impact. For all the countries, CO₂ fertilization effect, irrigation and heat tolerance varieties can offset most of the negative impact caused by climate change. Irrigation is an effective adaptation method, but it is expensive. So assess the costs and benefits of adaptation are further research needs. The negative climate impacts will exert a significant challenge on Cambodia’s rice production and competition with neighboring countries. To minimise the negative impacts of climate change on agriculture and improve crop yield, additional adaptive actions and policy options are required