Impacts Of Climate Change On Rice Yields In China

Food security has always been a major concern of the country.Due to the scarcity of cultivated land resources,the competition of food crops and other crops for land resources,it is more and more difficult to increase the yield of food crops by relying on the area planted.Under the overall situation that the volume is difficult to increase,the increase in yield level has become the direct driving force for increasing grain production.As the global climate continues to warm,China has become a sensitive area for climate change,and China's food production is increasingly affected by climate change.Under the circumstance that China's climate change trend is becoming more and more obvious,assessing the impact of climate change on China's rice yield is of great significance to national food security.Based on the data of rice planting structure and daily meteorological data at county level from 2006-2015,an econometric model of "rice yield-climate" was built on the basis of agricultural production function and rational farmers'behavior theory.Meteorological factors were constructed by the method of subdividing the stages of rice growth in crop science,and the two-way fixed-effect model was used to empirically analyze the different stages of rice growth.The effects of daily maximum temperature,daily minimum temperature,total precipitation and sunshine duration on rice yield were studied.The marginal effects of climate variables on rice yield and their contribution rates to rice yield were calculated.The results showed that:(1)Daily maximum temperature had a significant negative effect on rice yield at the stage of vegetative growth and reproductive growth,and daily minimum temperature had a significant positive effect on rice yield at the stage of vegetative growth;total precipitation had a significant positive effect at the stage of concurrent development of rice;sunshine time had a significant positive effect on rice yield at the stage of vegetative growth and reproductive growth.(2)Temperature has the greatest marginal effect on rice yield.In the stage of rice vegetative growth,increasing one standard deviation of daily maximum temperature would reduce rice yield by 67.596 kg/ha,and increasing one standard deviation of daily minimum temperature would increase rice yield by 43.543 kg/ha.In the concurrent stage of rice vegetative growth and reproductive growth,every additional standard deviation of precipitation will increase yield by 20.648 kg/ha,and every additional standard deviation of sunshine duration will increase yield by 43.633 kg/ha.During the reproductive growth stage,increasing one standard deviation of daily maximum temperature will result in a reduction of 69.805 kg/ha in rice yield,and every increase of sunshine duration per unit standard deviation will contribute to an increase of 53.403 kg/ha.(3)Compared with 2006,climate changes have great contribution to rice yield,scientific and technological progress plays a very important role in improving rice yield.Finally,according to the above analysis conclusions,this paper puts forward some countermeasures and suggestions for adapting to climate change in order to steadily increase the level of rice yield.