Paddy rice constitutes a staple crop in Korea. This study conducted sensitivity analysis to evaluate the vulnerability of paddy rice to future climate change, and compared temporal and regional characteristics to classify regions with unfavorable water balances. Rainfall Effectiveness Index for Paddy fields (REIP), the ratio of effective rainfall and consumptive use, was used as a sensitivity index. Weather data from 1971 to 2010 and future climate change scenarios Representative Concentration

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... athways (RCP) 4.5 and 8.5 were used to evaluate the sensitivity. Results showed an overall increase in water requirements and consumptive use. The REIP values were small for every period, except the 2040s, 2060s, and 2080s under scenario RCP 4.5, and the 2040s and 2080s under scenario RCP 8.5. Both climate change scenarios showed high sensitivity in regions Jeollabuk-do, Jeollanam-do, and Gyeongnam-do. However, regions Gyeonggi-do, Gangwon-do, and Chungcheongbuk-do had low sensitivity compared to other regions. The REIPs were used to categorize sensitivity into four types: low consumption-water rich, low consumption-water poor, high consumption-water rich, and high consumption-water poor. The Gangwon-do region had the highest number of regions that changed from the low consumption-water rich category to the high consumption-water poor category, making it a priority for measures to improve its adaptive capacity for climate change. can drastically affect its growth and yield. Many studies have examined the changes in growth and irrigation patterns of paddy rice due to climate change. For example, Doll [3] predicted that two-thirds of total irrigated fields around the world would experience an increase in irrigation requirements by 2070. Xiong et al. [4] studied irrigated areas in China with the GCM (General Circulation Models) A2 and B2 climate change scenarios, and predicted the area of irrigated fields would decrease overall and, consequently, have a significant impact on rice yield. Gondim et al. [5] studied the sensitivity of irrigation requirements and efficiency in A2 and B2 climate scenarios. Li et al. [6] simulated rice yield and growth processes based on Representative Concentration Pathways (RCP) 4.5 and 8.5 scenarios and showed that temperature increase would cause earlier vegetative periods and reduced crop yield. In Korea, Chung [7] used the HadCM3 (Hadley centre Climate Model 3) model and data from A2 and B2 to analyze agricultural water demand in the Nakdonggang region; the results predicted a decrease in unit duty of water and irrigation demands. Yun et al. [8] used the A1B scenario to analyze changes in reference evapotranspiration and water requirement; results showed an overall increase in both aspects. Lee et al. [9] used a crop growth model that implemented various climate change scenarios, and showed a decrease in future consumptive use and increase in crop yield of paddy rice. Yoo et al. [10] used a high-resolution climate scenario, RCP 8.5, to analyze the changes in paddy irrigation requirements and unit duty of water for different irrigation districts. The results predicted variation between different irrigation districts and seasons, but on average, the actual crop evapotranspiration would increase and, thus, the paddy water requirement and unit duty of water would increase. These studies above show that climate change threatens agricultural water security, and that the most immediate threat to future agriculture is climate change. Thus, it is essential to study the potential future risks and vulnerability caused by climate change to prepare for this threat, to promote agricultural production, and help prepare solutions, prioritize policies, and technologies. Vulnerability to climate change is a function of the character, magnitude, and rate of climate variation to which a system is exposed, its sensitivity, and its adaptive capacity [11, 12] . Sensitivity is defined as the degree to which a given community is affected in its current form, either adversely or beneficially, by climatic stresses [12] [13] [14] . For example, a community dependent on rain-fed agriculture is much more sensitive to changing rainfall patterns than one where mining is the dominant livelihood [1]. This study analyzed the changing trends in agricultural water demands and used a water balance model to evaluate the sensitivity of rice paddy fields. Furthermore, it used an index to compare the temporal and spatial sensitivity of paddy rice cultivation to climate change, and categorized 162 cities and counties throughout the country according to the sensitivity type of paddy.