| Since industrialization,all countries in the world have experienced obvious climate change characterized by warming.Climate change is particularly prominent in China,since the average surface temperature in China has increased by about 0.9-1.5℃ in the past 100 years,which is slightly higher than the increase of global average surface temperature during the same period.At the same time,extreme climate events such as floods and droughts occur frequently in some parts of China.Climate change is very prominent in the growth cycle of China’s main crops such as rice and wheat.China is the largest agricultural producer in the world and a major producer of major crops including rice and wheat.Rice and wheat are the most important food crops in China.Therefore,ensuring the yield of rice,wheat and other major food crops is an important part of stabilizing China’s food supply and ensuring China’s food security.Agriculture is the most direct and vulnerable sector affected by climate change.Current and future climate change is characterized by warming,and temperature is the most important meteorological factor affecting agriculture.It is of great significance to study the impact of temperature change on the yield of rice,wheat and other major food crops in China,so as to ensure China’s food security and formulate relevant climate policies.Agricultural processing industry is the key link in the agricultural industry chain.On the one hand,temperature change will affect the raw materials of agricultural processing enterprises,on the other hand,it will also affect their labor productivity and investment decisions.In view of this,this paper systematically studies the economic impact of temperature change on China’s agriculture from the perspectives of agricultural production and processing.Firstly,this paper examines the impact of temperature change on rice and wheat yield in China,and then analyzes the impact of temperature change on agricultural processing enterprises.So far,the quantitative analysis of the impact of temperature change on rice yield is mainly limited to tropical and subtropical countries and regions.These results show that the increase of the average daily minimum temperature will reduce the rice yield,while the increase of the average daily maximum temperature in the day will increase rice yield.The effect of the change of solar radiation on the rice yield is different according to its growth cycle.The above research results are generally based on the statistical analysis of small samples or experimental field data,and the stability and reliability of the research results need to be discussed.In addition,as the largest rice producing country in the world,the climate conditions,rice planting techniques and rice varieties of the main rice producing areas in China are quite different from those of the above countries,and the conclusions drawn from foreign literatures are difficult to be applied and extended to China.Several papers have studied the impact of temperature change on rice yield in China.However,due to different research data and research methods,their conclusions are also different.The existing foreign literature also studies the impact of temperature change on wheat production,and finds that wheat yield is affected by the average minimum temperature and the maximum temperature during plant’s growth cycle.The impact of temperature change on wheat yield is significant,but there is no consensus in previous studies.This may be due to different wheat varieties,ecological conditions,data and research methods used in the study area or country.A few studies have examined the impact of temperature change on wheat yield in China.Due to different data and research methods,they come to different conclusions.In order to accurately evaluate the impact of temperature change on wheat yield in China,it is necessary to further study the climate characteristics and ecological conditions of different wheat producing areas in China.The interdisciplinary research in this paper is a useful supplement to the existing research at home and abroad.The research results are helpful to understand the impact of temperature change on rice and wheat yield in China,and provide scientific basis for formulating relevant climate and agricultural policies.At present,it is a fast developing field to evaluate the impact of temperature change on agricultural economy.Most studies only investigate the impact of temperature change on crop production,and few studies analyze the impact of temperature change on agricultural processing enterprises.However,only considering the impact of temperature change on crop production can not fully evaluate the impact of temperature change on the agricultural sector.In view of this,this paper empirically analyzes the impact of temperature change on China’s agricultural processing sector by using the data of agricultural processing industry in Chinese industrial enterprise database from 1998 to 2007 and the weather data released by China Meteorological Administration.This paper includes six chapters.The main contents of each chapter are as follows:The first chapter of this paper is the introduction,which introduces the research background,clarifies the significant impact of climate change and the significance of assessing the economic impact of climate change,defines the key concepts of weather,climate and climate change,introduces the theoretical basis of this study,determines the research content,research framework,and summarizes the main contribution of this paper.The second chapter is literature review,which focuses on reviewing the impact of climate change on agriculture,including the research methods and empirical research in the field of the impact of climate change on agriculture.In addition,it also summarizes the impact of climate change on total economic output,total industrial and service output,labor productivity,population migration,international trade,energy use and poverty,etc.Finally,this chapter makes a review of the existing literature.In the third chapter,the effects of temperature change on early rice,middleseason rice and late rice yield in China are investigated.According to agronomic research and the characteristics of rice phenology,this chapter divides the rice growth season into three main stages,namely vegetative growth stage,reproductive growth stage and mature stage.By defining temperature variables according to the rice growth stage,this chapter investigates in detail whether the effect of temperature on rice yield is different in different stages of rice growth season.Existing studies have found that in tropical and subtropical regions,rice yield will decrease with the increase of the average daily minimum temperature.Contrary to previous studies,this chapter finds that the rising average daily minimum temperature will increase early rice and late rice yield in China,and the positive effect of temperature varies with different growth stages of rice.Consistent with the previous study,this chapter finds that precipitation had a small and negative effect on early rice and late rice yield.The effect of the average daily minimum temperature and precipitation on middle-season rice yield is not statistically significant.The effect of sunshine level on rice yield also varies with rice type and growth stage.Specifically,early rice yield will increase by 135-172 kg/ha for every 1℃ increase in the average daily minimum temperature at maturity stage,and late rice yield will increase by 186-210 kg/ha for every 1 ℃ increase in the average daily minimum temperature at reproductive growth stage.Under all the models considered in this chapter,the effect of the average daily minimum temperature on middle-season rice yield is not statistically significant.The findings of this chapter can provide valuable information for the development of effective rice cultivation projects and the formulation of climate adaptation strategies in China.In Chapter 4,the effects of temperature change on winter wheat yield in China are evaluated.Different from most previous literatures,this chapter finds that winter wheat yield will increase with the increase of the average daily minimum temperature,and this positive effect is most significant in the north of China.Consistent with previous studies,higher average daily maximum temperature will lead to a decrease in winter wheat yield in China.Specifically,winter wheat yield shows a positive response to the average daily minimum temperature rise in autumn and spring.Under different model settings,winter wheat yield will increase by 160-185kg/ha in autumn and 219-461kg/ha in spring for every 1℃ rise of the average daily minimum temperature.The effect of the daily minimum temperature in winter on the yield is also positive,but not statistically significant.Winter wheat yield will decrease by 109-145kg/ha in autumn and 178-451kg/ha in spring for every 1℃ rise of the average daily maximum temperature.The regression results of sub-regions are consistent with the above full sample benchmark results.The regression results of irrigation area and rain fed area show that the response of winter wheat yield in irrigation area to the increase of daily minimum temperature is different from that in rain fed area.Using global climate models Had GEM2-ES and Nor ESM1-M,the prediction results show that the average yield of winter wheat will decrease by 5.3-7.0% and 2.0-3.4% respectively by 2050.The fifth chapter studies the impact of temperature change on China’s agricultural processing enterprises.This chapter empirically analyzes the impact of temperature change on China’s agricultural processing sector by using the weather data released by China Meteorological Administration and Chinese industrial enterprise database from 1998 to 2007.It is found that there is a nonlinear relationship between temperature change and output of agricultural processing enterprises in China.Daily average temperature higher or lower than [21℃,24℃)will lead to the decline of output of agricultural processing enterprises,and daily average temperature higher than 30℃ has the greatest negative impact on the output of agricultural processing enterprises.In addition,this chapter finds that the increase of rainfall will lead to the decline of the output of agricultural processing enterprises in China,while the increase of solar radiation has a significant positive impact on the output of agricultural processing enterprises in China.Other weather variables（relative humidity,atmospheric pressure and wind speed）have no significant impacts on the output of agricultural processing enterprises in China.Secondly,the impact of temperature change on the output of different ownership enterprises is different.Specifically,the increase of high temperature days has no significant impact on the output of state-owned enterprises in agricultural processing enterprises,but will lead to the decline of the output of collective,private and foreign-funded agricultural processing enterprises,and has the greatest negative impact on private enterprises.Thirdly,due to the different climate conditions in different regions,the impact of temperature change on the output of agricultural processing enterprises in China has regional heterogeneity.Specifically,the increase of high temperature days will lead to the decline of the output of agricultural processing enterprises in North China,East China and Central South China,and has the greatest negative impact on North China.On the contrary,the increase of high temperature days will lead to the increase of the output of agricultural processing enterprises in Southwest China,but has no significant impact on the output of agricultural processing enterprises in Northeast and Northwest China.Finally,this chapter uses the Nor ESM1-M model and Had GEM2-ES model to predict and finds that the output of China’s agricultural processing enterprises will decrease by about1.7%-12.6% in the medium term due to the climate warming in the future under RCP2.6 and RCP8.5 greenhouse gas emission scenarios.In the long run,climate warming will reduce the output of agricultural processing enterprises by about 2.5%-22.3%.The sixth chapter summarizes the main conclusions and findings of the full text,puts forward policy suggestions,points out the shortcomings of the research and the possible research subjects in the future.This study provides a detailed and reliable analysis for understanding the economic impact of temperature change on China’s agriculture.The contributions of this paper are mainly reflected in three aspects: research content,research methods and research data.Specifically,it is as follows:In terms of research content,the main contributions of this paper are as follows.First,this paper expands the existing research years of temperature change on crop production,and investigates the impact of temperature change over more than 30 years on rice and winter wheat yield in China.Secondly,the data used in this paper contain detailed information of different rice types,so that this paper can systematically assess the impact of temperature change on early rice,middle-season rice and late rice yield in China under a unified framework.Thirdly,this paper studies the impact of temperature change on agricultural processing enterprises by using enterprise micro level data,and extends the existing research on the impact of temperature change on agricultural economy to agricultural downstream processing enterprises.In terms of research methods,the innovations of this paper have the following two aspects.Firstly,in order to investigate the impact of climate change on rice and wheat yield,three growth stages of crops are divided according to the growth cycle information of rice and wheat,and temperature variables of three different growth stages are constructed.Many existing studies assume that the effect of temperature on crop yield is cumulative and replaceable during crop growing season.By defining temperature variables according to the growth stages of rice and winter wheat,this paper can investigate whether the effect of temperature on yield is different in different stages of rice and winter wheat growth season.Secondly,the impact of temperature change on the output of enterprises may be nonlinear.Under different temperature levels,the impact of temperature rise on agricultural processing enterprises may be different.In this paper,we use the temperature bin variable as the temperature variable in the empirical analysis,so that we can investigate the nonlinear relationship between temperature change and the output of agricultural processing enterprises.In the research sample,the existing literature mainly uses the data at the provincial and county levels when investigating the impacts of temperature change on crop yield and agricultural land value.This paper uses the data at the enterprise level in the research of agricultural processing enterprises,which can provide micro level evidence for the impact of temperature change on agriculture.In addition,the use of micro enterprise level data enables us to examine the impact of temperature change on the ownership and regional heterogeneity of the output of agricultural processing enterprises in China.The findings are of great significance for the government and enterprises to formulate appropriate measures to deal with climate change. |
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