Agronomic Weather Measures in Econometric Models of Crop Yield with Implications for Climate Change

本篇論文係透過計量追蹤資料模型研究氣候變遷對於農業生產的潛在影響。首先就泰國的氣候變量在區域性稻米生產上之影響進行估計結果顯示溫度和降雨對於稻米之產量有顯著的影響。氣候變遷的模擬顯示稻米產量受到2030年以至2090年的氣候影響預計將減少4.56-33.77。另外由於氣候變遷的評估稻米產量的變動則將會增加。第二部分利用擴展隨機生產函數之動差模型加以檢視乾旱現象對於亞洲的稻米生產所造成的影響。迴歸結果顯示稻米生產受到乾旱指數的影響。2020年到2060年的乾旱現象預測指出未來乾旱的發生將減少亞洲的平均稻米產量6.93至13.18。此外乾旱在未來對於稻米產量的變化以及稻穀作物生長失敗的機率皆有顯著影響。本文的最後一部分設計了氣候指數型保險以擔保泰國蝦農面對氣候風險的影響其中蝦類生產函數的結果顯示指數型保險可以減少氣候風險對於泰國南部地區蝦子養殖戶的變動收入5.73。氣候變遷的模擬結果則是發現蝦農們的避險效率將在2020年到2060年氣候變遷的狀況下增加。本篇論文的主要貢獻在研究未來氣候變遷的潛在風險可以透過重大政策的決定降低天氣風險對於泰國和亞洲貴重農產品的影響。The general theme of this dissertation is the study of the potential impacts of climate change on agricultural production based on econometric panel data model. The first part estimates the regional rice production on climate variables in Thailand. Results indicate that temperature and precipitation have a significant impact on rice productions. The simulation impacts of climate change reveal that rice production is expected to decrease by 4.56 to 33.77% in response to the future climate scenarios for 2030 to 2090. The rice production variability is expected to increase due to climate change projection. The second part examines the impact of drought phenomenon on rice production by extending a stochastic production function to the moment-based model for rice production in Asia. Regression results show that the rice production have affect from drought index. The projection of future drought phenomenon for 2020s to 2060s reveals that the mean rice production in Asia would decrease by 6.92 to 13.18% in response to the future drought incidence. Besides, the projected change in drought incidence would affect rice production variability and production skewness. The last part of this dissertation designs the weather index insurance to assure shrimp farmers of weather risks in Thailand. Bases on the result of shrimp production function, the index insurance can be reduced the variance of the shrimp farmers’ revenue account for 5.73% in the South region. The simulation results of climate change indicate that shrimp farmers’ hedging efficiency is expected to increase in response to climate change scenario for the 2020 to 2060. The major contribution of this dissertation is potential impact of future climate change, which is very important for policy making decision to mitigate the effect of weather risks on the valuable agricultural product in Thailand and Asia.TABLE OF CONTENTSACKNOWLEDGEMENT I中文摘 要 IIABSTRACT IIITABLE OF CONTENTS IV LIST OF TABLES VIILIST OF FIGURES VIIICHAPTER 1 GENERAL INTRODUCTION1.1 Introduction 11.2 Organization of the Dissertation 4CHAPTER 2 ESTIMATING THE POTENTIAL EFFECTS OF CLIMATE CHANGE ON RICE PRODUCTION IN THAILAND2.1 Introduction 62.2 Rice Production model 82.2.1 The empirical study of climate change and crop yield 82.2.2 Just and Pope Production function estimation 102.2.3 Panel data set 122.3 Empirical Results 152.3.1 Pre-estimation specification test 152.3.2 Rice production function estimates 172.4 The Potential Effects of Climate Change Scenarios 202.5 Conclusions 24CHAPTER 3 MODELING THE IMPACTS OF DROUGHT ON RICE PRODUCTION IN ASIA AND FUTURE PROJECTIONS WITHCLIMATE CHANGE3.1 Introduction 263.2 Asia Drought Phenomenon and Projections 283.2.1 An overview of drought phenomenon 283.2.2 Droughts phenomenon in rice growing season and projection in coming decades 313.3 Modeling Rice Production and Drought Index 343.3.1 The empirical study of drought and crop yield 343.3.2 Econometric specification 353.3.3 Panel data set 413.4 The Estimation Results 433.4.1 Pre-estimation specification test 433.4.2 Rice production function estimates 463.5 The Potential Impacts of Climate Change Induced Droughts 493.6 Conclusions 52CHAPTER 4 THE POTENTIAL IMPACTS OF CLIMATE VARIABLES ONSHRIMP FARMING AND WEATHER INDEX INSURANCE WITHCLIMATE CHANGE IN THAILAND4.1 Introduction 544.2 An Overview of Weather Index Insurance 564.3 Panel Data Set 584.4 Weather Index Insurance Design 614.4.1 The specification of the weather variables 624.4.2 The estimation of the shrimp production function 624.4.3 The specification of the weather index insurance 684.4.4 The estimation of the risk reduction performance 714.5 The Potential Impact of Projected Climate Change 734.5.1 The quantification results of the impacts of climate change on shrimp yield 734.5.2 The impacts of climate change on shrimp farmers’ RRP 744.6 Conclusions 76CHAPTER 5 GENERAL CONCLUSION5.1 Conclusions 785.2 Limitations and Suggestions for Further Research 79REFERENCES 82LIST OF TABLESTable 2.1 Descriptive statistics of the date used in the estimations 14Table 2.2 Panel unit root test results 16Table 2.3 Specification test results for the panel data model 17Table 2.4 Estimated parameters for rice production mean function and production variability under Cobb-Douglas functional forms 18Table 2.5 Climate change scenarios 21Table 2.6 Results on percentage change in rice average production and production variability under projections of climate change 23Table 3.1 Comparison of commonly-used drought indices 29Table 3.2 Descriptive statistics of the date used in the estimations 42Table 3.3 Pre-estimation specification test results for the panel data model 44Table 3.4 Estimated parameters for rice production function 47Table 3.5 Results on percentage change in rice production by PDSI under projectionsof climate change 50Table 4.1 Summary statistics of the data on the region level 60Table 4.2 Regression of shrimp yield per unit land on time trend 63Table 4.3 Relationship between normalized shrimp yield and weather index 67Table 4.4 WII contract design for shrimp farming in the South of Thailand 72Table 4.5 The WII contract design under climate change scenarios 75LIST OF FIGURESFigure 2.1 Thailand rice production zones 13Figure 2.2 Regional effects of climate change on rice production in Thailand 24Figure 3.1 A map of Asia with grid point of major rice growing zone 31Figure 3.2 The distributions of historical PDSI in Asia rice growing season 32Figure 3.3 The distributions of projected PDSI in Asia rice growing season 33Figure 4.1 Thailand shrimp production zones 59Figure 4.2 The process of WII contract design 61Figure 4.3 The probability density function of average temperature (AT) 7