A general equilibrium analysis of conjunctive ground and surface water use with an application to Morocco

Groundwater resources (GW) account for nearly 30% of the world's sustainable water supplies. Yet, this resource, which is fraught with externalities, has largely been left unregulated. The economic literature on GW is predominantly of a partial equilibrium type. We analyze GW regulation in a general equilibrium setting, focusing on the stabilization value of GW under natural (drought) and economic (rural–urban water transfer) shocks. A general equilibrium approach allows evaluating direct and indirect effects of GW regulation on agriculture and nonagriculture sectors and extends the scope for water policy. The analysis is applied to Morocco by extending an existing computable general equilibrium (CGE) model to include ground and surface water (SW) resources. We study effects of (i) an increase in GW extraction cost (e.g., as a result of prolonged extraction beyond natural recharge that lowers the aquifer's water table), (ii) a transfer of SW from rural (irrigation) to urban (domestic) use, and (iii) a reduction of water availability due to severe drought. We estimate the value of GW and assess the direct (partial equilibrium) and indirect (general equilibrium) impacts. We find that GW plays a critical role in mitigating the negative effects of these types of shocks.     

Global models applied to agricultural and trade policies: a review and assessment

The continuing process of global integration bears implications for farmers and related supplying and processing industries in all parts of the world, but also for the rest of the world economy. An assessment of agricultural and trade policy impacts is bound to be complex and is often supported by quantitative modeling analysis. This article provides an assessment of the present state of applied modelling in the area of trade and agricultural policies. We provide in this paper a comparative assessment of alternative modelling approaches, considering a total of 16 partial equilibrium and general equilibrium models. The assessment includes theoretical modelling foundations, datasets employed and institutional aspects, such as model maintenance and dissemination of results. A typology of models is provided by structuring the assessment along a clear set of evaluation criteria.     

A Computable General Equilibrium Analysis of Agricultural Liberalisation: The Uruguay Round and Common Agricultural Policy Reform

This paper uses a computable general equilibrium model to assess the effects of the Uruguay Round (UR) and CAP reform. Detailed attention is given to the impact of the agricultural components of the UR and of the CAP reform on the agricultural and food-processing sectors of the EU. The CGE model used, while based on the standard Global Trade Analysis Project (GTAP) model, uses a more detailed representation of the UR and CAP policy changes than is usual in GTAP analyses of the UR effects. In so doing it assumes a degree of specificity of factors used in agriculture and makes appropriate agricultural policy variables endogenous. Finally, it assesses the consequences of assuming imperfect competition in all non-agricultural sectors.     

Modeling climate change and agriculture: an introduction to the special issue

This issue of Agricultural Economics is a special issue containing articles on model performance in assessing the effects of climate change, bioenergy policy, and socioeconomics on agriculture. The contributions present results from a global economic model intercomparison activity undertaken as part of the AgMIP Project ( www.agmip.org ). The origins of the comparison activities can be traced to a project that was organized by the OECD in late 2010 to compare results from three models. The current phase of the research includes 10 models and was designed in part to support of the IPCC fifth assessment report (AR5). The special issue includes seven peer‐reviewed articles that present thematic results from a range of modeling strategies, with partial and general equilibrium modeling as a high level distinction but a myriad of differences within these two model types. A central common element is harmonization on biophysical effects using crop models and socioeconomic effects using drivers from the Shared Socioeconomic Pathways developed as part of the AR5 process. The special issue provides broad insights into how the modeling communities approached the interactions of climate, socioeconomics, bioenergy policy on agricultural outcomes, including land use, prices, consumption, and production.     

Agent‐based Modelling of Climate Adaptation and Mitigation Options in Agriculture

Computer simulation models can provide valuable insights for climate‐related analysis and help streamline policy interventions for improved adaptation and mitigation in agriculture. Computable general equilibrium (CGE) and partial equilibrium (PE) models are currently being expanded to include land‐use change and energy markets so that the effects of various policy measures on agricultural production can be assessed. Agent‐based modelling (ABM) or multi‐agent systems (MAS) have been suggested as a complementary tool for assessing farmer responses to climate change in agriculture and how these are affected by policies. MAS applied to agricultural systems draw on techniques used for Recursive Farm Programming, but include models of all individual farms, their spatial interactions and the natural environment. In this article, we discuss the specific insights MAS provide for developing robust policies and land‐use strategies in response to climate change. We show that MAS are well‐suited for uncertainty analysis and can thereby complement existing simulation approaches to advance the understanding and implementation of effective climate‐related policies in agriculture.     

Agriculture’s Inter‐industry Linkages,Aggregation Bias and Rural Policy Reforms

As agricultural policy reform and its effects have become increasingly territorialised, analyses that attempt to explain or predict impacts need to be both more localised and to identify spill‐over effects. Local and regional general equilibrium approaches have become increasingly popular because they can extend predictions of policy shocks obtainable from partial equilibrium sectoral models to identify the wider effects. However, agriculture is usually described as a single sector in input–output accounts, whereas policy shocks that affect constituent commodities with differential impacts will have inter‐industry effects that are different to those implied by average input–output coefficients. Regionalisation of aggregated input–output tables adds further to these difficulties. The objective of this study is to develop a practical method for dealing with these problems. It describes the theoretical basis of aggregation bias and shows how it can be measured, in two contrasting case study regions in the UK and Sweden. Having established that this is a significant issue, a simple but effective procedure is demonstrated, based on additional information on variable costs, which transforms policy shocks from a direct change in agricultural output to that transmitted to the suppliers of inputs. This method provides an impact close to that which could be calculated if the general equilibrium system had indeed been disaggregated, and supports use of this approach in impact studies where insufficient time or funding are available for complete disaggregation of an agricultural sector’s regional accounts.     

International diffusion of gains from biotechnology and the European Union's Common Agricultural Policy

This paper analyses the impact of adopting or rejecting genetically modified (GM) crops in the European Union, taking into account the EU Common Agricultural Policy (CAP). In this paper the productivity impact of genetically modified organisms (GMOs) differs across crops, taking factor biased technology change into account. The transfer of knowledge across countries is modelled as a process of endogenous knowledge spill-overs. Analysis with a multi-region applied general equilibrium model shows that the CAP protects farm income and production despite non-adoption of the more productive GM crops in the EU. The EU will forgo substantial benefits in terms of economic welfare if it bans GM imports.     

Modeling linkages between climate policy and land use: an overview

Agriculture and forestry play an important role in emitting and storing greenhouse gases. For an efficient and cost-effective climate policy, it is therefore important to include land use, land-use change, and forestry (LULUCF) explicitly in economy-climate models. This article gives an overview and assessment of existing approaches to include LULUCF into partial and general equilibrium economy-climate models. For each class of models, we describe different examples, their treatment of land, and their potential for and applicability to policy analysis, as well as their shortcomings. We identify data requirements and conceptual problems, and provide suggestions for future research.     

Tax reform and the natural resource industries

Tax reforms passed by Federal Parliament in June 1999 include rationalising indirect taxes, a tax mix change, and a smaller fiscal surplus. The impact or first-round effects on the natural resource industries indicate large gains. Important second-round reactions, particularly a real currency appreciation, erode most of, and in some cases more than all of, the first-round gains. A complete assessment requires the use of general equilibrium models.     

Dynamic factor demand equations in U.S. and Canadian agriculture

This research provides one of the first empirical estimates of a data-based dynamic factor demand model for American and Canadian agriculture. Models such as these deserve more widespread use in the empirical analysis of agriculture. These models have the advantage that they do not impose inappropriate dynamics on the data. Rather they permit the data to select the appropriate dynamics. We use a model originally developed by Anderson and Blundell. This model is a general first-order dynamic model which contains as testable hypothesis several simpler models. This model permits us to estimate the long-run agricultural production structure as a subset of the dynamic parameter estimates. We will test this long-run structure for symmetry, homotheticity and neutral technical change. The estimated models may be used to test for three alternative dynamic structures. In the limit, dynamics may not be needed and we can test for the static long-run equilibrium model. Two intermediate cases are the autoregressive and the partial adjustment models which are simpler than the general model but still include dynamics. Our results suggest that the long-run equilibrium model is unsatisfactory in both countries. A dynamic model is needed. In both countries, the two more restricted dynamic models are rejected. The general dynamic model is required. In Canada, the long-run equilibrium structure is homothetic with neutral technical change. In the United States, homotheticity is also accepted but neutral technical change is rejected.     

Comparing supply‐side specifications in models of global agriculture and the food system

This article compares the theoretical and functional specification of production in partial equilibrium (PE) and computable general equilibrium (CGE) models of the global agricultural and food system included in the AgMIP model comparison study. The two model families differ in their scope—partial versus economy‐wide—and in how they represent technology and the behavior of supply and demand in markets. The CGE models are “deep” structural models in that they explicitly solve the maximization problem of consumers and producers, assuming utility maximization and profit maximization with production/cost functions that include all factor inputs. The PE models divide into two groups on the supply side: (1) “shallow” structural models, which essentially specify area/yield supply functions with no explicit maximization behavior, and (2) “deep” structural models that provide a detailed activity‐analysis specification of technology and explicit optimizing behavior by producers. While the models vary in their specifications of technology, both within and between the PE and CGE families, we consider two stylized theoretical models to compare the behavior of crop yields and supply functions in CGE models with their behavior in shallow structural PE models. We find that the theoretical responsiveness of supply to changes in prices can be similar, depending on parameter choices that define the behavior of implicit supply functions over the domain of applicability defined by the common scenarios used in the AgMIP comparisons. In practice, however, the applied models are more complex and differ in their empirical sensitivity to variations in specification—comparability of results given parameter choices is an empirical question. To illustrate the issues, sensitivity analysis is done with one global CGE model, MAGNET, to indicate how the results vary with different specification of technical change, and how they compare with the results from PE models.     

EU‐wide Economic and Environmental Impacts of CAP Greening with High Spatial and Farm‐type Detail

In this paper we analyse the economic and environmental impacts of CAP greening introduced by the 2013 CAP reform using the CAPRI model. CAPRI captures the farm heterogeneity across the EU and it allows to depict the implementation of the greening measures in high detail while integrating the environmental effects and the market feedback of the simulated policy changes. The simulated results reveal that the economic impacts (land use, production, price and income) of CAP greening are rather small, although some farm types, crops (fallow land and pulses) and Member States may be affected more significantly. The CAP greening will lead simultaneously to a small increase in prices and a small decrease in production. Farm income slightly increases because the price effects offset the production decline. Similarly to economic effects, the environmental impacts (GHG emissions, N surplus, ammonia emissions, soil erosion, and biodiversity‐friendly farming practices) of CAP greening are small, although some regions may see greater effects than others. In general, the environmental effects at EU level are positive on a per hectare basis, but the increase in UAA can reverse the sign for total impacts. Overall, simulated GHG and ammonia emissions decrease in the EU, while the total N surplus, soil erosion and biodiversity‐friendly farming practices indicator slightly increase due to the CAP greening.     

Output and input bias effects of U.S. direct payments

This study examines the national effect of U.S. direct payments on the extent and direction of biased technical change on U.S. agriculture. We also assess the economic significance of the estimated bias effects for economic policy modeling endeavors involving a reduction of domestic support payments. A two outputs (livestock and crops) and four inputs (labor, capital, land, and material) translog cost function was estimated from national time series (1948–2011) data. Results indicate that payments do not induce output‐biased technical change. We do find evidence of Hicksian bias that is land using and material input saving attributable to support payments. Global computable general equilibrium simulations suggest that price and output effects of discontinuing direct payments are 1/4 to 1/3 the size once the bias effects are incorporated.     

A multi-sector intertemporal optimization approach to assess the GHG implications of U.S. forest and agricultural biomass electricity expansion

This study applies an intertemporal partial equilibrium model of the U.S. Forest and Agricultural sectors to assess the market, land use, and greenhouse gas (GHG) implications of biomass electricity expansion. Results show how intertemporal optimization procedures can yield different biomass feedstock portfolios and GHG performance metrics at different points in time. We examine the implications of restricting feedstock eligibility, land use change, and commodity substitution to put our results in the context of previous forest-only modeling efforts. Our results highlight the importance of dynamic considerations and forest and agricultural sector interactions on projecting the GHG effects of biomass electricity expansion in the U.S.     

The Land Use Impacts of the EU Biodiesel Policy: Assessing the Direct,Indirect and Induced Effects

This paper deals with the controversial measure of indirect land use changes of the European biodiesel policy. Two studies sponsored by the European Commission find significant, but contrasted, land use impacts for the different vegetable oils used for biodiesel production. The first study uses an aggregate computable general equilibrium model capturing direct, indirect and induced effects. The second more recent study uses a biotechnical partial equilibrium model providing a detailed representation of the indirect effects occurring through the livestock sectors. We develop an original economic emulator to understand the diverging key results of these studies and test their sensitivity. We find that the direct and indirect effects on vegetable oil and land markets explain most of the differences. We also find that indirect effects on the feed markets and the induced effects have less influence on the biodiesel results. We finally argue that the development of emulators as done here can help to understand complex policy assessments.     

The Impact of Pillar II Funding: Validation from a Modelling and Evaluation Perspective

We extend the Common Agricultural Policy Regionalised Impact Modelling System (CAPRI) with a regional computational general equilibrium (CGE) model to estimate the effects of the Pillar II of the Common Agricultural Policy. Our aim is to assess the modeling approach by comparing the scenario results with observations from the evaluation reports for rural development, supplemented with expert interviews and findings from the literature. For this purpose, an ex‐post scenario is developed for Germany that models the effect of the Pillar II measures in 2006. We observe a moderate impact, namely, an increase in agricultural income (5%) and agricultural land use (0.15%), particularly grassland, and a substitution of arable land with grassland. This effect leads to a total increase in agricultural production, particularly of beef, and to an increase in total greenhouse gas emissions and total nitrogen surplus for Germany. Greenhouse gas emissions and nutrient surpluses per ha, however, are reduced. We observe that farm investment programmes displace private investment. The evaluation reports confirm the moderate impact and our major results, as does the comparison with other literature. However, the conclusions about agri‐environment measures and their impact on income differ. The most important difference between our results and the evaluation reports and majority of the present literature is that we also quantify the joint effect between the whole economy and policy measures, with some contradictory effects.     

Agenda 2000 Reform of the CAP and its Impacts on Member Member States: A Note

We evaluate the Agenda 2000 reform of the CAP for each of the 15 member states of the EU, accounting for general equilibrium effects and bilateral trade links. Results reflect the impacts in 2008 projected from a 1997 database. In most member states, output of crops falls and there is a switch in the use of arable land from oilseeds to cereals. Output of cattle also falls, but that of milk, pigs and poultry increases. Total farm income falls in 11 member states, although livestock producers throughout the EU gain. Consumer price indices fall everywhere. In terms of GDP, Luxembourg, Finland, Ireland and Portugal gain the most; Germany, Greece and the UK gain the least; and Spain loses. The net budgetary cost to the EU of the reform package is estimated to be an additional €3,203 million. Thus, further cuts in support are of paramount importance if the EU is to be prepared for the accession of new members.     

Land‐use change trajectories up to 2050: insights from a global agro‐economic model comparison

Changes in agricultural land use have important implications for environmental services. Previous studies of agricultural land‐use futures have been published indicating large uncertainty due to different model assumptions and methodologies. In this article we present a first comprehensive comparison of global agro‐economic models that have harmonized drivers of population, GDP, and biophysical yields. The comparison allows us to ask two research questions: (1) How much cropland will be used under different socioeconomic and climate change scenarios? (2) How can differences in model results be explained? The comparison includes four partial and six general equilibrium models that differ in how they model land supply and amount of potentially available land. We analyze results of two different socioeconomic scenarios and three climate scenarios (one with constant climate). Most models (7 out of 10) project an increase of cropland of 10–25% by 2050 compared to 2005 (under constant climate), but one model projects a decrease. Pasture land expands in some models, which increase the treat on natural vegetation further. Across all models most of the cropland expansion takes place in South America and sub‐Saharan Africa. In general, the strongest differences in model results are related to differences in the costs of land expansion, the endogenous productivity responses, and the assumptions about potential cropland.     

Spatial Market Efficiency and Policy Regime Change: Seemingly Unrelated Error Correction Model Estimation

We investigate the degree to which the wheat markets of France, Germany, and the United Kingdom are in spatial equilibrium and how reforms to the CAP affect the speed of convergence to the long–run relationship. Due to the interrelationship among these markets and the nonstationarity of our data we introduce a seemingly unrelated regression–augmented Dickey–Fuller and error correction methodology. We argue this methodology is more efficient than ordinary cointegration and error correction models. Empirically we find strong evidence of efficient spatial markets and conformity to the law of one price. Market liberalization reforms in the EU increased the comovement of domestic and world wheat prices; our post–Uruguay Round price transmission elasticity was 0.183.     

Partial Market Liberalization and the Efficiency of Policy Reform: The Case of the European Dairy Sector

This article analyzes the efficiency of partial market liberalization and policy reform with an application to the European dairy sector. In a second best world, partial moves toward market liberalization are not always efficiency improving. We develop a general equilibrium model to investigate the efficiency implications of discrete changes in government policy. The analysis covers price and quantity instruments used in both domestic and trade policy. We derive simple conditions under which partial market liberalization is efficiency improving. We apply the approach to agricultural policy reform in the European dairy sector and identify market liberalization scenarios that are "not" efficiency improving.