Assessment of climate change iimpact on crop yields in Northern Taiwan using principal component analysis

Climate change affects all agriculture activities. When long-term climate pattern has changed, the weather factors, such as temperature and rainfall, might affect the quality and quantity of crop growth. Paddy rice is the most important crop productions in Taiwan and accounts for more than 70% of total water resources usage. The quantity of rice productions is a very important index for food security and agriculture management. This study utilizes the Decision Support System for Agrotechnology Transfer (DSSAT) model to analyze the variations of growth days and quantity of paddy rice under climate change. The Weather Generator Model (WGEN) was used to generate daily rainfall and daily mean temperature. Maximum and minimum daily temperature and solar radiation were then estimated by regression functions of daily mean temperature and daily rainfall from historical data. Rice productions were estimated by the DSSAT model. The Taiwan Climate Change Projection and Information Platform Project (TCCIP) provides future climate projections and the A1B scenarios of Special Report on Emissions Scenarios were selected in this study. To understand the dominant factors affecting crop yields under climate change, the Principal Component Analysis(PCA) was applied to analyze DSSAT results for both periods of baseline data (1985~1990) and near future data (2020~2039). Accumulated solar radiation, accumulated growing degree, crop water requirement and growing days were retrieved for performing PCA. Climate variations projected by ensemble models and CM3 model showed accumulated growing degree before blossom is the most important factor, while in MK3_0 mode is the accumulated solar radiation before blossom.