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.     

Cost‐effective strategies to mitigate multiple pollutants in an agricultural catchment in North Central Victoria,Australia

Strategies to reduce phosphorus and sediment yields are identified for two Australian catchments using a nonlinear optimisation model. This provides novel insight into the cost‐effective management of dual pollutants of water courses in Australia. A strong degree of complementarity between the two pollutants is highlighted, given the adsorption of phosphorus to sediment that augments the value of gully and streambank management for mitigation. However, the relationship between the two pollutants is asymmetric. A 30 per cent reduction in phosphorus yield achieves a 75 per cent reduction in sediment yield in one catchment, while a 30 per cent reduction in sediment yield achieves only a 12 per cent reduction in phosphorus yield. Sediment abatement costs are low given the efficiency of gully and streambank management. A 30 per cent phosphorus reduction lowers profit by 3–7 per cent, while a 30 per cent sediment reduction lowers profit by around 1 per cent. Land‐use optimisation requires spatial heterogeneity in land‐use and gully/streambank management responses. Overall, this research demonstrates the need to determine whether one pollutant is more important than another, while recognising the potential that mitigation practices possess for the reduction of multiple emissions during their evaluation.     

Traditional farm expansion versus joint venture remote partnerships

Traditionally, farms expand by buying out a neighbour. But might remote partnerships be a better way of expanding a farm business given projected climate change and price volatility? This question is addressed using farm business financial modelling. Representative farms at 27 locations in Western Australia are constructed to enable comparison of the value of buying out a neighbour versus expansion using geographically distant joint venture (JV) partners. The farm models consider economies of size, bulk purchase price discounts, the variability and correlation of returns associated with farm expansion, and impacts of climate change. Random selection of a remote partner generates little improvement in wealth; on average only 2.3 and 1.6 per cent, respectively, under current and projected future climate across all locations. However, there is large variation in wealth appreciation opportunities for each location and between locations. Preferred partnerships are a function of each farm's characteristics. Locations highly preferred as JV partners under current climate are similarly preferred partners under projected future climate. The main sources of additional wealth come from economies of size advantages, risk‐spreading benefits of combining geographically separated farms and bulk discounts. Farmers seeking business expansion will often benefit greatly from careful selection of a remote partner.     

Quantifying the impact of farmers' social networks on the effectiveness of climate change mitigation policies in agriculture

To reduce agricultural greenhouse gas (GHG) emissions, farmers need to change current farming practices. However, farmers' climate change mitigation behaviour and particularly the role of social and individual characteristics remains poorly understood. Using an agent-based modelling approach, we investigate how knowledge exchange within farmers' social networks affects the adoption of mitigation measures and the effectiveness of a payment per ton of GHG emissions abated. Our simulations are based on census, survey and interview data for 49 Swiss dairy and cattle farms to simulate the effect of social networks on overall GHG reduction and marginal abatement costs. We find that considering social networks increases overall reduction of GHG emissions by 45% at a given payment of 120 Swiss Francs (CHF) per ton of reduced GHG emissions. The per ton payment would have to increase by 380 CHF (i.e., 500 CHF/tCO₂eq) to reach the same overall GHG reduction level without any social network effects. Moreover, marginal abatement costs for emissions are lower when farmers exchange relevant knowledge through social networks. The effectiveness of policy incentives aiming at agricultural climate change mitigation can hence be improved by simultaneously supporting knowledge exchange and opportunities of social learning in farming communities.     

Marginal abatement costs of greenhouse gas emissions: broadacre farming in the Great Southern Region of Western Australia

Broadacre agriculture is a major emitter of greenhouse gases (GHG). To improve efficiency of climate change policies, we need to know the marginal abatement costs of agricultural GHG. This article combines calculations of on‐farm GHG emissions with an input‐based distance function approach to estimate the marginal abatement costs for a broadacre farming system in the Great Southern Region of Western Australia. The results show that, in the study region, the average marginal abatement cost for the 1998–2005 periods was $29.3 per tonne CO₂‐e. Farms with higher crop output shares were found to have higher marginal abatement costs. Overall, our results indicate that broadacre agriculture is among the lowest cost sources of GHG mitigation.     

Empirical evaluation of nonpoint pollution policies under agent heterogeneity: regulating intensive dairy production in the Waikato region of New Zealand*

Models used for policy evaluation rarely consider firm heterogeneity, despite its importance for instrument design. This study considers agent heterogeneity explicitly in the evaluation of policies for nonpoint pollution control through the integration of decomposition and calibration procedures for programming models. The application concerns the regulation of nitrate leaching from intensive dairy production in the Waikato region of New Zealand. Failing to represent firm heterogeneity leads to widely different estimates of mitigation costs, relative to where heterogeneity is considered. Variation in baseline emissions and the slopes of abatement cost curves between firms renders a differentiated policy less costly than a uniform standard. However, the relative values of these policies are not broadly different, as firms required to do the most abatement – intensive farms with large baseline pollutant loads – can do so more cheaply, on average.     

Is it too late to stabilise the global climate?

Assessment of the feasibility of stabilising the global climate requires consideration of trajectories for emissions of carbon dioxide and other greenhouse gases. This study presents a simple and robust analysis of feasible emissions trajectories. Consideration of feasible trajectories suggests that if the current pace of mitigation efforts is sustained, the likely outcome will be stabilisation at concentrations close to 500 parts per million. Such an outcome will imply a higher than 50 per cent probability of substantial damage from climate change and an enhanced risk of a catastrophic outcome.     

How Sure Can You Be? A Framework for Considering Delivery Uncertainty in Benefit Assessments Based on Stated Preference Methods

The economic valuation of benefits resulting from environmental policies and interventions often assumes that environmental outcomes are certain. In fact, these outcomes are typically uncertain. This article proposes a methodological approach to incorporate delivery uncertainty into benefit estimation based on stated preference methods. In the study design of a choice experiment survey on land‐based climate change mitigation, we explicitly include delivery uncertainty as the risk that a proposed mitigation project fails to deliver emission savings. We find that respondents’ preferences do not change significantly after being confronted with choices that included risk of failure. However, failure risk itself does have an important impact on the preferences for delivering emission reductions. We show that delivery uncertainty can have a large impact on stated preference estimation of benefits of public programmes. This result should condition conclusions drawn from ex‐ante environmental cost‐benefit analyses that make use of such benefit estimates.     

Economic vulnerability and regional implications of a low carbon emissions future

Climate change, as well as associated mitigation efforts, will substantially disrupt some economies. Seemingly inevitable market and policy changes will push economies to transition away from reliance on industries with higher carbon emissions and bring transient economic impacts, especially in regions that are currently heavily reliant on such industries. This situation is not unusual in a global context. To underpin better‐informed decisions that enable a smoother economic transition to a low‐emissions future, we developed a ‘latent economic vulnerability to emissions reduction’ (LEVER) index, which maps and explores regions that are more likely to be economically impacted from climate change mitigation. Thus, this paper provides an analysis and discussion of the potential regional implications of a future low‐emissions economy, with the analysis contextualised for the state of Queensland, Australia. Given this case study, the economic impacts and future of coal‐fired power stations, coal mining and renewable energy are discussed.  The LEVER index weighs the risk of high carbon economic exposure against the variability in carbon economic resilience from employment in low‐emission sectors across local economies. We find that between 3 and 6 per cent of Queensland regions are assessed as having a very high latent economic vulnerability to increased decarbonisation of industrial activities. To promote a smoother transition, these regions will require targeted investments and strategies to enable their transition towards lower carbon‐intensive systems, while maximising economic and social outcomes.     

Farmers and their groves: Will cost inefficiency lead to land use change?

Increased forest areas and climate change mitigation are policy goals enhanced by expanding private forest ownership. This study shows transfer of land from farms owning forested acreage associated with low quality land and high production costs achieves such goals. Calculated cost efficiency scores show a large gap between the most and least efficient farms, and farms with forests are less cost efficient. Land reforestation through subsidy programs could replace income from agricultural production. We illustrate that farms from the applied FADN panel could reforest 45,000 hectares, binding about 0.5 mln tons of carbon annually without limiting food or feed supply.     

Carbon offsets and agriculture: Options,obstacles, and opinions

While carbon offsets in agriculture can play a role in addressing climate change, they are not a perfect substitute for direct emission reductions. As shown in this paper through various arguments and case studies, climate policies in Canada have avoided the use of offsets to be sold in carbon markets, preferring instead to incentivize adoption of best management practices (BMPs) that provide environmental benefits along with climate mitigation benefits. We argue that this is a preferred policy option due to the perils and pitfalls inherent in the measurement and monitoring required to identify offset credits. While an appropriate approach might be to penalize Canadian farmers for any emissions their activities cause, this may do more harm than good. Canadian agricultural production is highly efficient and technologically advanced; therefore, reductions in Canada's contribution to the global food supply will result in less-efficient production occurring elsewhere (i.e., leakage) that increases global greenhouse gas emissions.     

Technical,Allocative, Cost and Scale Efficiencies in Bangladesh Rice Cultivation: A Non‐parametric Approach

Applying programming techniques to detailed data for 406 rice farms in 21 villages, for 1997, produces inefficiency measures, which differ substantially from the results of simple yield and unit cost measures. For the Boro (dry) season, mean technical efficiency was 69.4 per cent, allocative efficiency was 81.3 per cent, cost efficiency was 56.2 per cent and scale efficiency 94.9 per cent. The Aman (wet) season results are similar, but a few points lower. Allocative inefficiency is due to overuse of labour, suggesting population pressure, and of fertiliser, where recommended rates may warrant revision. Second‐stage regressions show that large families are more inefficient, whereas farmers with better access to input markets, and those who do less off‐farm work, tend to be more efficient. The information on the sources of inter‐farm performance differentials could be used by the extension agents to help inefficient farmers. There is little excuse for such sub‐optimal use of survey data, which are often collected at substantial costs.     

Evaluating Input Standards for Non‐Point Pollution Control under Firm Heterogeneity

The efficacy and cost of input standards for reducing nitrate pollution from New Zealand dairy production are evaluated. In contrast to previous studies, firm heterogeneity is explicitly considered through the novel integration of efficient techniques for the calibration and decomposition of large optimisation models. Nitrogen fertiliser application should not be targeted by policy given its minor role in determining emissions. In contrast, livestock intensity is an appropriate base for regulation given its strong correlation with pollutant load. Abatement cost increases as stocking rate declines, but this can be offset at low levels of regulation through utilising slack feed resources to improve per‐cow milk production. Both uniform and differentiated input standards based on livestock intensity achieve substantial decreases in pollutant load at moderate cost. However, because of disparity in the slopes of abatement cost curves across firms, a differentiated policy is more cost‐effective at the levels of regulation required to achieve key societal goals for improved water quality.     

Effects of EU dairy policy reform for Dutch dairy farming: a primal approach using GMM estimation

This paper estimates a production function for milk using ageneralised method of moments estimator to avoid the endogeneityproblem. Using the first-order conditions for profit maximisation,the economic effects for individual Dutch dairy farms of the2003 EU dairy policy reform are analysed. With an expected milkprice decrease of 21 per cent, profit decreases on average by22 per cent. EU direct payments compensate for roughly 53 percent of this fall in profit. The profit reduction means that69 per cent of all small farms have negative income from farming,compared with 15 per cent in the initial situation.     

The potential impact of markets for irrigation water in Italy and Spain: a comparison of two study areas*

The viability of irrigated systems in Southern Europe is closely linked to efficient institutional settings and water‐allocation mechanisms. A significant, although not widely used, mechanism for water allocation is an intra‐sectorial water market. The objective of this paper is to evaluate to what extent water markets may contribute to the improvement of the efficiency of water allocation and to the profitability of irrigated agriculture. The related issues of water allocation among farm types and farm specialisation are also addressed. The analysis is based on a basin‐level linear programming model, comparing the situation with and without a market. It includes both fixed and variable transaction costs and estimates their combined effects on market performances. The model is applied in two areas in Southern Italy and Spain, and simulates the behaviour of different farm types, derived from cluster analysis on a sample of farms in each area. The paper confirms that water markets could potentially improve the economic efficiency of water use, in terms of higher profit per hectare, given limited water availability. The potential improvements are associated with a more intense specialisation of farms and are strongly differentiated among farmers, particularly where significant restrictions to water availability occur. This corroborates the expectations of institutional difficulties in implementing water markets. However, the exchanges, and consequently the potential effects of water markets, are heavily affected by the actual level of water availability, as well as the size and the structure (fixed vs. proportional) of transaction costs. The paper calls for a more in‐depth analysis of the connections between market performances and institutional settings, as related to the issue of water‐agriculture policy design and coordination.     

Estimating the range of economic impacts on farms of nutrient leaching reduction policies

Declining agricultural incomes, increasing concern over rural poverty and sporadic crises such as those of Bovine Spongiform Encephalopathy (BSE) and Foot and Mouth Disease mean that the imposition of further costs on U.K. agriculture are likely to be politically and socially sensitive. Such additional costs are however on the agenda with the implementation of the Water Framework Directive (WFD; European Commission, 2000 ). The WFD aims to achieve “good ecological status” in EU water bodies reducing, inter alia, diffuse pollution from agriculture. In this study, we assess four possible WFD measures proposed to the U.K. Department for Environment, Food, and Rural Affairs: reducing inorganic fertilizer application, conversion of arable land to ungrazed grassland, reducing livestock stocking rates, and reducing livestock dietary N and P intakes. For each measure, changes in farm gross margins (FGMs) are estimated using a dataset of over 2000 farms. In contrast to previous analyses, which have focussed upon mean responses on stylized farms, our approach allows the analysis of the range of impacts across a wide variety of real‐world farms and farm types. Findings reveal high variability in impacts. Cost‐effectiveness analysis indicates that, on average, cropping farms seem capable of reducing nutrient leaching in a more cost‐efficient way than livestock or dairy enterprises.     

How important is improving food availability for reducing child malnutrition in developing countries?

Do increases in the food supply per person in a country, i.e., national food availability, contribute substantially to reductions in malnutrition among its children? This paper sets out to answer this controversial question using panel data from 63 developing countries over 1970–1996. This paper gives evidence in support of a statistically significant and strong positive impact of national food availability on child nutrition, finding that increased food supplies have resulted in significant reductions in malnutrition since the 1970s despite population increases over the period. However, per‐capita food supplies have a declining marginal impact: their effect is quite strong for countries with very low food availability (e.g., most countries in sub‐Saharan Africa and South Asia), but weak or non‐existent for those with high levels (e.g., most countries in the Near East and North Africa). Further, non‐food factors, such as women's education and status and the quality of health environments, are also important determinants of children's nutritional status. Depending on the state of food availability in any particular geographic area and relative costs, these factors may merit greater priority in policies to reduce malnutrition.     

Cost-effectiveness of alternative green payment policies for conservation technology adoption with heterogeneous land quality

This paper quantitatively analyses the cost‐effectiveness of alternative green payment policies designed to achieve a targeted level of pollution control by heterogeneous microunits. These green payment policies include cost‐share subsidies that share the fixed costs of adoption of a conservation technology and/or input reduction subsidies to reduce the use of a polluting input. The paper shows that unlike a pollution tax that achieves abatement through three mechanisms, a negative extensive margin effect, a negative intensive margin effect and a technology switching effect, a cost‐share subsidy and an input reduction subsidy are much more restricted in the types of incentives they provide for conservation of polluting inputs and adoption of a conservation technology to control pollution. Moreover, they may lead to varying levels of expansion of land under production. Costs of abatement with alternative policies and implications for production and government payments are compared using a simulation model for controlling drainage from irrigated cotton production in California, with drip irrigation as a conservation technology.     

Productivity of New York Dairy Farms Measured by Nonparametric Malmquist Indices

The productivity of 70 individual New York dairy farms, decomposed into technical efficiency change and technological change components, was measured annually from 1985 to 1993 from output distance functions estimated using nonparametric programming methods. Technology is measured regressively only if it is regressive to all previous periods rather than just the immediate previous period. Productivity increase averaged 2.6 per cent annually, mostly from gains in technological improvements, since average efficiency decreased slightly. Twenty-five per cent of the farms failed to increase productivity sufficiently over the period to offset the decreased ratio of output to input prices.     

The optimal diffusion of mitigation options for environmental management

A new direction for evaluating pollution policy is proposed, focused on optimal investment pathways for mitigation capital. The approach allows practitioners to draw directly from key principles in the diffusion literature. A two‐stage, policy‐development framework is introduced. The first stage consists of empirical modelling to assess optimal diffusion pathways for diverse mitigation options. The second involves determining the relative strengths of different policy actions to address diffusion rates or maximum levels of adoption that diverge from optimal levels. The advantages of this new approach are demonstrated in an agri‐environmental context, concerning the off‐site impacts of intensive agriculture on water quality. The viewpoint provided by the novel approach establishes the importance of adoptability – alongside the traditional measures of abatement effectiveness and cost – for mitigation practices in policy assessment. The key role that durable mitigation capital plays in addressing dynamic externalities is demonstrated, alongside the importance of structured diffusion cascades for alternate mitigation options.