Effects of instantaneous groundwater availability on irrigated agriculture and implications for aquifer management

Groundwater is an important input for agricultural production in many parts of the world. Aquifer depletion has been shown to affect the rate that groundwater can be extracted from an aquifer. In this paper, we develop an analytical framework that accounts explicitly for the effects of limited instantaneous groundwater extraction rate (well capacity) on a producer's irrigation decisions. We show that limited well capacities can affect the producer’s groundwater use and profit. We draw three important insights from these findings. First, we demonstrate that the price elasticity of demand for groundwater is higher for lower well capacities. Second, farmers’ irrigation decisions are non-monotonic with respect to well capacity and climate conditions. Under a drier climate, producers with greater well capacities increase their groundwater use, and producers with lower well capacities reduce their water use. Third, through numerical analysis, we show that considering spatial heterogeneity in well capacities is important for estimating the cost-effectiveness and distributional impacts of groundwater management policies. Our results shed new light on the importance of extraction capacity for groundwater management policies and the potential impacts of climate change on agricultural production.     

区域创新能力、农业经济与生态环境协调发展关系研究

首先,建立4种空间权重矩阵,运用Moran′I检验证实了农业生态环境空间相关性;其次,构建基于库兹涅茨曲线的空间计量模型,将区域创新能力纳入研究框架,运用2005-2013年我国内地31个省份面板数据实证分析区域创新能力、农业经济与生态环境协调发展关系,并对各影响因素空间效应进行分解;最后,对统计结果进行稳健性检验。结果表明,我国农村经济发展与生态环境间呈正U型曲线关系,而区域创新能力提升将显著改善农业生态环境,并进一步促进我国农业经济可持续发展。     

A general equilibrium assessment of climate change–induced loss of agricultural productivity in Nepal

The impact of climate change on agriculture has been one of the most discussed topics in the literature on climate change. Multi-regional computable general equilibrium (CGE) models have frequently been used to examine the impact of climate change on agriculture. However, these studies do not focus on country-specific issues related to the link between climate change and agriculture. This paper aims to address this gap by investigating the economy-wide impacts of climate change on Nepalese agriculture. Nepal makes an interesting case study as it has one of the most vulnerable agricultural economies in South Asia. This paper develops a comparative static multi-household CGE model to trace the direct and indirect impacts of climate change in Nepal. The results suggest that climate change has a significant negative impact on the overall Nepalese economy due to the induced loss of agricultural productivity. The results further reveal that rural households in Nepal, whose livelihoods primarily depend on subsistence farming, will face additional climate change–induced stresses due to already overstrained poverty and a weak social welfare system. The results indicate an urgent need to mainstream adaptation strategies to lessen the negative impacts of any climate change–induced loss of agricultural productivity in Nepal.     

The Impact of Climate Change on Agriculture: Findings from Households in Vietnam

This paper examines farm household-level impacts of climate change by examining the relationship between climatic variables and Vietnamese agricultural output. The Ricardian technique is applied with panel data which accounts for both adaptation strategies and household characteristics. This study proposes a two-stage Hsiao model to correct for collinearity between climatic variables and individual effects. The results show that in the dry season, increases in temperatures are beneficial to all farms in the warmer southern regions, while increases in precipitation will damage only irrigated farms in the Central and South regions. The impact of higher temperature in the wet season is similar, except that it will negatively affect net revenue of irrigated farms in the long run. More rainfall in the wet season will increase net revenue in the North region only. Finally, this study combines the estimated results with future climate scenarios to predict how future changes in climate will affect farmers on aggregate.     

气候变化对湖南省农业水旱灾害的影响研究方法探讨

随着全球气候变化的不断加剧,区域气温、降水、辐射等都发生了重大变化,其对农业发展也具有重要影响,研究气候变化对湖南农业水旱灾害的影响及适应性对策有利于减小灾害性天气及气候系统对湖南省农业的影响,适时找出适合湖南区域特点的应对措施,并进一步完善当前全球气候变化对农作物生长研究的不足。基于英国哈德莱气候中心的区域气候模式PRECIS系统的区域尺度气候情景模拟结果,借助于GIS技术运用EPIC和SWAT模型分别模拟未来不同气候情景下湖南水稻产量和水资源的变化,通过对过去50年气候变化及其对水稻模拟产量的影响研究,可以总结湖南省应对气候变化引发的水旱灾害的策略和方法,并进一步提出未来气候变化情景下的适应性对策,可以为政府和相关决策部门应对未来水旱灾害的适应性对策提供参考依据。     

我国粮食主产区农业高质量发展的区域差异及收敛性分析

全面认识粮食主产区农业高质量发展差异的空间特性，为推动粮食主产区农业高质量的协调发展提供有益启示。本文从新发展理念出发，构建农业高质量发展综合评价指标体系，运用加入时间变量的熵值法测度2003-2018年我国粮食主产区农业高质量发展水平，利用Dagum基尼系数揭示其发展的区域差异大小及其来源，并采用多种收敛方法考察其收敛性特征。结果显示：粮食主产区农业高质量发展水平较低，在波动中呈总体上升趋势；粮食主产区农业高质量发展存在显著的区域差异，其差异在波动中呈总体下降趋势，区域内差异与区域间差异交替成为区域差异的主要来源；粮食主产区农业高质量发展具备典型的收敛和收敛特征，分区域和分时期的收敛性具有明显的异质性特征。因此为提升农业高质量发展水平和缩小区域差距，需要进一步深化农业供给侧结构性改革，积极发展农业新业态和新模式，并通过“追赶效应”和“以高带低”拉动机制，推动粮食主产区农业高质量发展的跨区域协同提升。     

考虑空间效应的中国肉牛生产区域集聚及成因

基于新经济地理学理论,运用空间计量经济方法,对中国肉牛生产区域布局的变动及其成因进行实证分析。结果表明:中国肉牛生产区域呈明显的空间集聚特征;2000年以来,肉牛生产地区逐步从非农就业机会较多的中原等区域向饲草资源丰富、经济发展水平较低的东北地区、西北地区和西南地区转移。进一步研究其成因,结果表明:资源条件、经济环境、技术因素和空间互动效应对肉牛生产的区域集聚有不同程度的影响,其中技术、空间误差自相关性、农业劳动力数量、草地面积和粮食产量对中国肉牛生产的区域集聚具有明显的正向影响,而非农就业机会则具有明显的负向影响。     

Economic and Welfare Impacts of Climate Change on Developing Countries

The impact of global climate change on developing countries is analyzed using CGE-multimarket models for three archetype economies representing the poor cereal importing nations of Africa, Asia, and Latin America. The objective is to compare the effects of climate change on the macroeconomic performance, sectoral resource allocation, and household welfare across continents. Simulations help identify those underlying structural features of economies which are the primary determinants of differential impacts; these are suggestive of policy instruments to countervail undesirable effects. Results show that all these countries will potentially suffer income and production losses. However, Africa, with its low substitution possibilities between imported and domestic foods, fares worst in terms of income losses and the drop in consumption of low income households. Countervailing policies to mitigate negative effects should focus on integration in the international market and the production of food crops in Africa, and on the production of export crops in Latin America and Asia.     

我国价格支持政策对粮食生产的影响研究

文章利用2004年和2006年稻谷主产地区样本数据,运用倍差分析方法,着重考察了价格支持政策对稻谷生产的影响,研究发现,没有证据表明价格支持政策对稻谷面积扩大带来明显的激励作用,而且还存在较低的成本有效性（有着较大的成本节约的空间）;现存耕地面积、有效灌溉比重和农业劳动力数量会在一定程度上影响稻谷生产。为此,本文提出,要坚定不移地保持耕地面积不减少,加强以农田水利为重点的农业基础设施建设,推进农业社会化服务体系长足发展。     

中国粮食生产区域特征与成因研究——市场化改革以来的实证分析

中国各省区粮食产量占全国粮食总产的比例的动态计算和统计分析表明 ,市场化改革以来 ,中国粮食生产具有稳定的区域变化特征。计量检验显示 ,农村人均耕地资源与非农产业就业拉力是中国粮食生产区域特征的重要影响因素。本研究提示 ,中国粮食生产区域特征具有持久性 ,它对区域粮食政策和省区际粮食贸易将产生深远影响。     

A dynamic multi-commodity model of the agricultural sector: A regional application in Brazil

This paper develops a dynamic model to analyze the development process in the agricultural sector. Formulated as a recursive linear programming model, it contains several commodities as outputs, farm and regional resource constraints on owned and purchased inputs-including working capital-and several farm sizes. The objective function is assumed to be separable for each farm size and additive for the region and measures for each year the net expected revenues from crop and livestock production less an investment charge. Prices are exogenous. The model is applied to a rapidly developing agricultural region in Southern Brazil and tested for its ability to trace regional farm sector development over a decade. It is then used to analyze the impact of alternative agricultural policies including price and credit subsidies.     

中国棉花生产技术效率及其影响因素分析

深入分析我国棉花生产技术效率及其影响因素,对于稳定和提高棉花产量、保障国民经济健康发展有着重要意义.本文首先对我国12个主产省棉花生产的技术效率进行测算,并重点考察了其时序波动和地区差异特征;其次探讨了棉花生产技术效率的主要影响因素,通过构建计量模型,对可能的影响因素进行了回归分析.结果表明,2001-2009年,我国棉花生产技术效率的区域差异和时序波动特征明显,西北棉区技术效率最高且波动最小,其次是黄河流域棉区,长江流域棉区技术效率最低且波动最剧烈;适度规模经营、农民受教育程度、农业科技人员数量和非农产业发展对棉花生产的技术效率有正效应,非农人口比例和异常天气的负面影响较大.文章最后给出了相应的政策建议.     

山东省农业经济空间布局——基于探索性空间数据的实证分析

采用探索性空间分析方法,以县域为空间单元,刻画了1999年、2007年和2010年山东省农业总产出及五大类主要农产品产出的空间分布模式,并对山东省农业产出的空间相关性进行了测定。研究结果显示:山东省农业总产出的空间分布基本呈"核心-边缘"模式,空间相关性和区域布局具有一定的稳定性;粮食、棉花和油料作物的生产在空间上具有明显的集聚特征和经济外溢性,肉类生产的上述效应相对较弱。最后提出:在开放经济及市场经济的背景下,制定考虑空间影响的农业政策,才能真正合理引导各区域农业协调生产,最终促进农业综合生产能力的提升。     

Policy modeling on the GDP spillovers of carbon abatement policies between China and the United States

This paper simulates the GDP spillover effects between China and U.S. caused by the implementation of different climate protection policies. It is based on a combination of several climate protection models, which are the State-contingent Model and the Demeter Model, and the GDP Spillovers Model, known as the Mundell–Fleming model. From the simulation results, it is concluded that whether the United States implements policies on increasing carbon sink or not makes very little difference on the total output in the U.S. and the GDP spillovers toward China. However, the spillover impact of American carbon abatement policies on China experiences a varying trend that rises from negative to positive. These simulation results show that the climate protection policies of one country will have positive impact on the GDP spillovers of another country in the long term. This paper is focused on two conditions while simulating the GDP for both China and the U.S. Condition A within the simulations ignores the impact of GDP spillovers of foreign countries, while condition B takes the impact of GDP spillovers of foreign countries into consideration. Furthermore, this paper presents the simulated GDP of China and the U.S. under different scenarios and analyzes the level of GDP spillovers between the two countries. This paper concludes that carbon abatement policies in the U.S. have a larger and more noticeable GDP spillover effects to China.     

A worldwide analysis of trend in crop yields and yield variability: Evidence from FAO data

The trend in crop yields and yield variability affects food security and impact agricultural and food policies. Recent studies in this area have either focused only on one country or performed global analysis on a handful of crops. We provide the first worldwide analysis of trend and variability for 8088 country-crop yield series taken from the FAO database, employing a robust estimator to cope with the adverse statistical effects of outliers. More than half of the series display a slowdown in yield growth due to a closing of the gap between realised and attainable yields as well as to agricultural policies promoting more sustainable agricultural practices. Around one fourth of the series show also an increase in yield variability as a consequence of climate change and changes in farm management practices. Yield variability is highest in Eastern Europe, Central Asia and Middle East and North Africa, where food security may be threatened.     

Relations of the regional Brazilian cane agro-industry with the national economy: analysis applied to the Centre-South and North-Northeast

Cane, sugar and ethanol production in Brazil has been divided between two major production regions, the Centre-South (CS) and the North-Northeast (NNE), which present very different productivity, and henceforth production costs. The CS average productivity is more than 72 tonnes of cane per hectare, while average productivity in the NNE is 49 tonnes per hectare. The objective of the study was to establish interrelations between the cane agro-industry and other regional sectors and with the overall Brazilian economy. This framework was used to compare a demand impact upon regional cane production upon the regional and the overall Brazilian economy. An interregional input–output matrix was used to characterize how regional demand impacts on both regional and overall Brazilian economies. Rasmussen–Hirschman indexes, together with a pure linkage index were used for the analysis. In addition, production multipliers, with and without considering endogenous family consumption were estimated. The results showed that a positive demand impact upon the cane agro-industry produces a greater impact upon the NNE compared to the CS, considering income effects, indicating that cane production is more important for the NNE than for the CS. These results can be useful to establish priorities for development policies for the country.     

促进、加速与溢出：数字经济发展对区域创新绩效的影响

在系统揭示数字经济对区域创新绩效的促进作用、边际递增的非线性影响和空间溢出机制的基础上,基于2013—2018年我国省级面板数据,构建区域数字经济发展评价指标体系,运用面板固定效应模型、门槛回归和空间杜宾回归分析方法,实证检验数字经济对区域创新绩效的影响。研究结果表明：数字经济发展显著促进区域创新绩效提升;数字经济发展对区域创新绩效、发明创新绩效均有边际效应递增的非线性影响;数字经济发展对邻近地区的创新绩效和非发明创新绩效有显著负向影响,但对发明创新绩效影响不显著。据此,提出相应政策建议。     

Global warming and livestock husbandry in Kenya: Impacts and adaptations

This paper examines the economic impact of climate change on livestock production in Kenya. We estimate a Ricardian model of net livestock incomes and further estimate the marginal impacts of climate change. We also simulate the impact of different climate scenarios on livestock incomes. The Ricardian results show that livestock production in Kenya is highly sensitive to climate change and that there is a non-linear relationship between climate change and livestock productivity. The estimated marginal impacts suggest modest gains from rising temperatures and losses from increased precipitation. The predictions from atmospheric ocean general circulation models suggest that livestock farmers in Kenya are likely to incur heavy losses from global warming. The highest and lowest losses are predicted from the Hadley Centre Coupled model (HADCM) and Parallel Climate Model (PCM) respectively, based on the Intergovernmental Panel on Climate Change A2 Special Report on Emissions Scenarios. The paper concludes that in the long term, climate change is likely to lead to increased poverty, vulnerability and loss of livelihoods. Several policy interventions are recommended to counter this impact.     

Subsidies under uncertainty: Modeling of input- and output-oriented policies

Agricultural subsidies play an essential role in agricultural and rural development in many developed economies. Countries have implemented agricultural subsidy policies with a focus on food security and environmental protection. Agricultural production is risky and uncertain, influencing the efficiency of agricultural subsidies. This study develops a theoretical framework to analyze the effects of production uncertainties on the efficiency of agricultural subsidy policies under the double constraints of food security and environmental protection. The basic model is investigated under six different conditions, and expanded research also is presented. Our models show that uncertainty, including output, cost, and price uncertainties, and technology conversion efficiency significantly affects the efficiency of agricultural subsidies. Under high technology conversion efficiency, output-oriented subsidies are appropriate for food security and environmental protection goals. Policymakers should take both uncertainty and production efficiency into consideration when choosing between input-oriented and output-oriented subsidy policies.     

The productivity impact of climate change: Evidence from Australia's Millennium drought

The economic impact of climate change has usually been estimated based on changes in average weather condition and is often measured in terms of immediate loss of output or profit. Yet little is known about the impact of extreme weather event, in particular its impact on productivity in the medium to long term. Using Australia's Millennium drought as a case of extreme weather event and applying the synthetic control method, we show that severe droughts occurred between 2002 and 2010 has brought down agricultural total factor productivity by about 18 percent in Australia over the period, contributing significantly to the country's long-term slowdown of agricultural total factor productivity growth. Our results highlight the significance of productivity impact of extreme weather events that has been overlooked when accessing the economic impact of climate change.