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.     

Structural Change of European Dairy Farms – A Cross‐Regional Analysis

Previous analyses of dairy farm structural change focus on the variation over time in one or a small number of regions. We present an EU‐15 cross‐regional analysis of the development of dairy farm numbers in different size classes over the period 1995–2005. Our purpose is to measure the explanatory relevance and effect of key factors suggested in the theoretical and empirical literature on structural change. Apart from the unprecedented scope, the underlying Markov chain analysis also contributes by combining observed transitions in micro (farm level) data with macro (sector level) data on farm numbers. Results show widely significant impacts of most considered explanatory variables, but also reflect and illuminate the complexity of the underlying processes.     

The economic impacts of technology and climate change: New evidence from U.S. corn yields

Over the past century, U.S. farmers have been offered a steady stream of new agricultural technologies, and more recently, experienced climate change. Because these two events have been occurring simultaneously, identifying their separate effects is difficult, and misimputation is easy. This article explicitly examines the economics of technical change and the interaction between weather and technology as revealed in a half century of panel data on U.S. Midwest rainfed state‐average corn yields. Observed yields reflect two components: yield potential and damage to the potential caused by weather and pests. Yield potential is modeled as a stochastic production frontier where nitrogen fertilization, public corn research, and introduction and adoption of biotech corn seeds impact yield potential and excess heat impacts nitrogen productivity. The yield‐damage/damage‐control function permits biotech corn plants to abate adverse effects of weather and pest events. Results include the following: nitrogen use, public corn research, and biotech seed‐corn adoption increase yield potential; soil moisture stress reduces yield potential, and excess heat severely reduces nitrogen productivity. Biotech corn plants abate yield damage caused by soil moisture stress but not excess heat.     

The fourth industrial revolution,agricultural and rural innovation,and implications for public policy and investments: a case of India

The Indian Government and public–private partnerships are developing and disseminating a dizzying number of innovative, networked solutions, broadly known as the Digital India initiative, to increase the efficiency of safety nets and worker productivity and to improve life. Yet, challenges to turn the power of information and other technologies into a farmer‐friendly technological revolution for India's 156 million rural households are considerable, including: (1) reliable, up‐to‐date, location‐specific message content for a diverse agriculture to help stratified households shift to productive, knowledge‐intensive agriculture as a business—government, private sector, and civil society have big roles to play; (2) digital literacy, i.e., teaching farmers how to choose and use apps, even where the digital divide is absent; apps are, or soon to be, in regional languages; and (3) monitoring actual use and impacts on users’ lives by understanding the adoption and adaptation processes. These challenges call for bottom‐up, complementary investments in physical, human, and institutional capital, and farmer‐friendly e‐platforms, while forging ahead with many top‐down policy and institutional reforms currently underway, in which progress is real and constraints holding back greater success are better understood.     

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.     

The transmission of world maize price to South African maize market: a threshold cointegration approach

This article seeks to provide an explanation for the relationship between domestic maize price in South Africa and world maize prices in order to evaluate comovement and transmission of world prices to domestic prices in sub‐Sahara African countries. This is done by comparing nested and nonnested models that capture different forms of nonlinearity in the price spread. Adopting a Bayesian approach that allows for comparison of models using Bayes factor, we found that the relationship between South African price and world price for maize indicates the presence of nonlinearity in price transmission with three regimes that is triggered by the price spread in previous period.     

Farm-level adaptation to climate change in Western Bangladesh: An analysis of adaptation dynamics,profitability and risks

Using long-term district-level climate data and a case study from a drought-prone village in western Bangladesh, this research explored trends in climate change, and analysed farmers’ adaptation dynamics, profitability and risks. This is the first study of its kind for drought-prone areas in Bangladesh.Farmers perceived climate changes included increases in temperature and decreases in rainfall which were as consistent with the trends of Chuadanga climate records. Farmers’ adaptation measures included changes in cropping systems, cropping calendars, crop varieties, agronomic practices, crop diversification and improved animal husbandry. Reducing environmental stress, ensuring self-sufficiency in staple crops (mainly rice) and other crop production practices, and enhancing economic viability of farm enterprises have underpinned these adaptations. Off-farm and non-farm wage employment, temporary migration, self-employment and educating children, constituted the core non-farm adaptation strategies.Emerging cropping systems like maize/cucumber and maize/stem amaranth/rice were economically more viable than the traditional rice/rice and rice/maize systems. Despite some uncertainties, farming was preferred to off-farm work, generating higher returns to labour for all cropping systems. Limited access to stress-tolerant varieties, extension services and affordable agricultural credit, combined with high production costs, variability in crop yields and output prices, are the main barriers to adaptation. Stronger agricultural research and support services, affordable credit, community-focussed farming education and training are critically important for effective adaptation to climate change.     

The impacts of climate change on Australia and New Zealand: a Gross Cell Product analysis by land cover*

This paper examines the newly constructed geographically scaled economic output measure, Gross Cell Product (GCP), of Australia and New Zealand to quantify the impacts of climate change in the region. The paper discusses advantages of using the GCP instead of the Gross Domestic Product. The paper reveals that the GCP falls sharply as temperature increases in the region. A 1°C increase in temperature would decrease the productivity with an elasticity of ?2.4. A 1 per cent decrease in precipitation would decrease productivity with an elasticity of ?2.3. However, forest vegetation on the coasts will benefit from initial warming. We find that the changes in climate means are potentially more harmful than changes in climate variability. In the long term, a 3.4° warming coupled with 6.6 mm decrease in rainfall would decrease the GCP by 34 per cent by 2060. The damage is largely accounted for by population effects. The paper confirms that Australia is highly constrained by climate and geographic factors.     

The structural transformation of African agriculture and rural spaces: introduction to a special section†

This article briefly introduces a special section on the structural transformation of African agriculture and rural spaces. The five papers that comprise this special section all draw on household‐level microdata to explore important aspects of the salient changes taking place in the world's most agrarian and poorest continent.     

Spatial determinants of productivity growth on agri‐food Spanish firms: a comparison between cooperatives and investor‐owned firms

This study analyses the effect of the spatial factor, location, and interaction effects among peer companies, on the productivity growth of agri‐food companies in Spain. With this aim, we build a productivity growth index and apply a multiequational Seemingly Unrelated Regression on a sample of 344 Spanish cooperatives and investor‐owned firms for the period 2010–2012. Our findings show that agri‐food firms are influenced by spatial factors finding interesting differences between cooperatives and investor‐owned firms. With regard to the geographical location, cooperatives in the western of Spain show higher productivity growth rates, whereas investor‐owned firms in the northeast of Spain present better results. The interaction effect among closer peer companies is also a relevant factor to determine the productivity growth in agri‐food companies. This factor is more relevant for cooperatives than for investor‐owned firms.