The Impact Of Climate Change On Crop Production

In recent years,global climate change,characterized by rising temperatures,has become a focus of worldwide attention.China is a sensitive and highly affected region of climate change.From 1951 to 2017,China's warming rate reached 0.24? every 10 years,which is significantly higher than the global average level in the same period.China is a country with large population and small land.Maintaining stable growth of grain production and other major agricultural products and ensuring national food security,especially food security has always been the core objective of China's agricultural policy.With the rapid growth of China 's economy,the regional pattern of China's agriculture has undergone significant changes.As one of the most economically developed coastal provinces,Zhejiang has changed from the main grain producing area to the main selling area.How to realize the steady growth of grain and other major agricultural products in the main selling areas such as Zhejiang,is of great strategic significance to ensure national food security.Therefore,the Zhejiang Provincial Committee proposed to actively deal with the adverse effects of climate change on agriculture,enhance the ability of agriculture to adapt to climate change and improve the stability of agricultural production in the province in 2016.Therefore,in this context,it is of great practical significance to study the impact of climate change on agriculture in Zhejiang Province.Based on a comprehensive review of relevant studies at home and abroad and the climate data from 1987 to 2016,this paper firstly describes the change characteristics of temperature,precipitation and sunshine in Zhejiang in the past 30 years by using climatic statistics methods such as climatic tendency rate and Mann-Kendell climate jump test,then uses H-P filter analysis technology to decompose into the trendy yield and climate yield of eight kinds of main crops such as rice,wheat,maize and barley in Zhejiang and analyzes the effects of climate change on the fluctuation of production of main crops in Zhejiang Province according to relative climatic yield,average yield reduction and coefficient of variation of yield reduction.On this basis,based on the agricultural input-output data of 73 counties(districts and cities)and the climatic data of 17 surface meteorological observatories from 1996 to 2015,a spatial error model(SEM)including climatic factors,socio-economic factors and production input factors is constructed by using the method of spatial econometrics model.The marginal effects of climatic factors such as temperature,precipitation and sunshine,as well as extreme climatic events such as extreme high temperature(low temperature)and extreme precipitation on the production of 8 major crops in zhejiang province are analyzed.Furthermore,based on the total factor productivity theory,the total factor productivity and its technological progress index,technological efficiency and scale efficiency of Zhejiang agriculture under the consideration of climate change are empirically estimated by using DEA-Malmquist method and Zhejiang agricultural total factor productivity without considering climate change is compared in order to reflect the impact of climate change on Zhejiang agricultural total factor productivity.Based on the above empirical results,this paper further puts forward relevant policy recommendations for Zhejiang agriculture to cope with climate change.The main conclusions of the study are as follows:(1)Temperature rise has become the main feature of climate change in Zhejiang in recent 30 years with the rate of temperature reaching 0.42 C/10a,which is higher than the national average level.The precipitation and sunshine mean do not change significantly,but there are some interannual fluctuations and regional and seasonal differences.(2)In the past 30 years,the impacts of climate change on yield fluctuation of different crops in Zhejiang Province are obviously different of which rice is less affected by climate change and the number of bad years and disaster years is the lowest;while maize,wheat,barley and oilseed rape are more affected by climate disasters,the average yield reduction rate is higher and the coefficient of variation of yield reduction is also higher than other crops,which is impacted by climate change greater.(3)There are obvious differences in the marginal effects of different climatic factors on the yield of different crops.The effect of effective accumulated temperature on the menu yield of early rice,mid-late rice,wheat and oil shows an inverted "U" pattern,which increases by 3.61%?4.42%,2.95%?3.64%,3.12%?3.63%and 1.14%?2.18%respectively when the temperature increases by 1?.The effect of effective accumulated temperature on the yield of maize and soybean is significantly negative,but the yield of maize and soybean could not be reduced by 1? increase.The effect of precipitation on yield per unit area of wheat,barley,potato and soybean also shows an inverted "U”pattern,in which the increase of precipitation has the most obvious marginal effect on yield per unit area of potato.The effect of precipitation on yield per unit area of early rice,mid-late rice and maize is significantly negative.The effect of sunshine duration on the yield of all crops is not obvious.(4)The negative impact of extreme climate events on crop yield is very obvious,of which the yield of early rice and late rice by 3.9%?5.1%and 2.3%?2.8%respectively can be reduced with increasing extreme high temperature each day,oilseed rape yield will decrease by 0.5%?0.8%with every day of increasing extreme low temperature days and the average annual yield reduction of middle and late rice due to extreme precipitation in the growing period also reaches 14.1?17.7 kg/mu.(5)Natural and man-made adaptation in crop production can mitigate the impact of climate change on crop yield increase or decrease to a certain extent and improve the stability of crop yield per unit area.There is an obvious substitution relationship between input of production factors such as fertilizer,machinery and irrigation and temperature and precipitation changes,but the relationship with sunshine is not obvious.(6)Climate change has hindered the improvement of agricultural production frontier in Zhejiang Province and has a negative impact on agricultural TFP in Zhejiang Province.There are obvious temporal and spatial differences in Zhejiang Province.The impact of climate change on agricultural TFP in plain areas is greater than that in coastal areas and hilly areas,which means that ignoring climate change factors may overestimate agricultural TFP in Zhejiang Province.As time goes by,the negative impact of climate change on agricultural TFP in Zhejiang shows a trend of expanding coverage and increasing degree,which means that the adverse impact of climate change on agricultural TFP in Zhejiang may be further deepened in the future.(7)In order to cope with the adverse effects of climate change on agriculture,the paper puts forward four policy proposals:adjusting crop planting structure,promoting stable and increased agricultural production,improving field management technology,mitigating the impact of extreme weather,strengthening agricultural technology training,improving farmers'adaptability and improving climate early warning mechanism and doing a good job in advance.The main contributions of this study are as follows:(1)In terms of research content,this paper takes eight crops as the research object to reveal the difference of impacts of climate change on different crop production;at the same time,the paper takes Zhejiang as an example to study the impacts of climate change on agriculture,expands the existing related research and the results are more realistic and pertinent.(2)From the perspective of research,the paper studies the impacts of climate change on agriculture from the perspectives of yield volatility,yield marginal impact and agricultural TFP to expand the limitations of existing research from the perspective of yield marginal impact.(3)In the research methods,on the one hand,the paper introduces the concepts and methods in the field of Agronomy and Climatology to analyze the fluctuation of crop yield under climate change and on the other hand,it constructs a panel model of spatial error including standardized spatial weight matrix to estimate the marginal impact of climate change on crop yield,and at the same time,it introduces climate change factors into agricultural TFP research to explore the impact of climate change on agricultural TFP,which is rare in existing studies.