Addressing Uncertainty in Efficient Mitigation of Agricultural Greenhouse Gas Emissions

The agricultural sector, as an important source of greenhouse gas (GHG) emissions, is under pressure to reduce its contribution to climate change. Decisions on financing and regulating agricultural GHG mitigation are often informed by cost‐effectiveness analysis of the potential GHG reduction in the sector. A commonly used tool for such analysis is the bottom‐up marginal abatement cost curve (MACC) which assesses mitigation options and calculates their cumulative cost‐effective mitigation potential. MACCs are largely deterministic, typically not reflecting uncertainties in underlying input variables. We analyse the uncertainty of GHG mitigation estimates in a bottom‐up MACC for agriculture, for those uncertainties capable of quantitative assessment. Our analysis identifies the sources and types of uncertainties in the cost‐effectiveness analysis and estimates the statistical uncertainty of the results by propagating uncertainty through the MACC via Monte Carlo analysis. For the case of Scottish agriculture, the uncertainty of the cost‐effective abatement potential from agricultural land, as expressed by the coefficient of variation, was between 9.6% and 107.3% across scenarios. This means that the probability of the actual abatement being less than half of the estimated abatement ranged from <1% (in the scenario with lowest uncertainty) to 32% (in the scenario with highest uncertainty). The main contributors to uncertainty are the adoption rate and abatement rate. While most mitigation options appear to be ‘win–win’ under some scenarios, many have a high probability of switching between being cost‐ineffective and cost‐effective.     

Reducing greenhouse gas emissions from agriculture: Avoiding trivial solutions to a global problem

Three steps are required to successfully and efficiently reduce greenhouse gas (GHG) emissions from agriculture: (i) identification of the most GHG polluting farms, (ii) determining appropriate mitigation options for these farms, and (iii) selection between these options on the basis of their cost effectiveness. Carbon footprints of a sample of farms together with an analysis of the Kyoto Protocol show the difficulties encountered at each step. These difficulties are caused by: (i) failure to agree which functional unit to use to measure GHG emissions and pollution swapping; (ii) weaknesses in the Kyoto Protocol's territorial/production based accounting methodology, and (iii) lack of cost-effectiveness data. One consequence is that farmers may adopt mitigation activities that reduce their farm's, the UK agriculture sector's and the UK's emissions whilst inadvertently increasing global emissions: a trivial solution because it fails to address GHG emissions as a global problem. These difficulties, together with estimated agriculture sector marginal abatement cost curves that suggests emission reduction from all cost effective mitigation activities will not deliver targeted GHG emission reductions, means policy focus must be on demand rather than supply-side measures: the benefits and disadvantages of cap and trade mechanisms and carbon taxes are briefly discussed within an agricultural context.     

Climate change reduces the mitigation obtainable from sequestration in an Australian farming system

Agricultural research on climate change generally follows two themes: (i) impact and adaptation or (ii) mitigation and emissions. Despite both being simultaneously relevant to future agricultural systems, the two are usually studied separately. By contrast, this study jointly compares the potential impacts of climate change and the effects of mitigation policy on farming systems in the central region of Western Australia’s grainbelt, using the results of several biophysical models integrated into a whole‐farm bioeconomic model. In particular, we focus on the potential for interactions between climate impacts and mitigation activities. Results suggest that, in the study area, farm profitability is much more sensitive to changes in climate than to a mitigation policy involving a carbon price on agricultural emissions. Climate change reduces the profitability of agricultural production and, as a result, reduces the opportunity cost of reforesting land for carbon sequestration. Nonetheless, the financial attractiveness of reforestation does not necessarily improve because climate change also reduces tree growth and, therefore, the income from sequestration. Consequently, at least for the study area, climate change has the potential to reduce the amount of abatement obtainable from sequestration – a result potentially relevant to the debate about the desirability of sequestration as a mitigation option.     

What Drives Marginal Abatement Costs of Greenhouse Gases on Dairy Farms? A Meta‐modelling Approach

This paper examines the relationships between the marginal abatement costs (MAC) of greenhouse gas (GHG) emissions on dairy farms and factors such as herd size, milk yield and available farm labour, on the one hand, and prices, GHG indicators and GHG reduction levels, on the other. A two‐stage Heckman procedure is used to estimate these relationships from a systematically designed set of simulations with a highly detailed mixed integer bio‐economic farm‐level model. The resulting meta‐models are then used to analyse how MAC vary across farm‐level conditions and GHG measures. We find that simpler GHG indicators lead to significantly higher MAC, and that MAC strongly increase beyond a 1–5% emission reduction, depending on farm attributes and the chosen indicator. MAC decrease rapidly with increasing farm size, but the effect levels off beyond a herd size of 40 cows. As expected, the main factors driving gross margins per dairy cow also significantly influence mitigation costs. Our results indicate high variability of MAC on real life farms. In contrast to time consuming simulations with the complex mixed integer bio‐economic programming model, the meta‐models allow the distribution of MAC in a farm population to be efficiently derived and thus could be used to upscale to regional or sector level.     

Carbon accounting tools: are they fit for purpose in the context of arable cropping?

The agricultural sector contributes 9% towards total UK greenhouse gas emissions and so may offer significant potential as a sector to help meet national and international emission reduction targets. In order to help farmers manage their emissions and to encourage more sustainable farming, several carbon accounting tools are now available. This article describes a short study that selected five suitable tools and compared their performance on nine European arable farms, concentrating on the crop production components, to determine how useful they are for assisting in the development of site-specific mitigation strategies and how well they would perform within farm assurance or benchmarking schemes. The results were mixed, with some tools better designed for identifying mitigation opportunities than others. The results also showed that, quantitatively, the results are highly variable between tools and depended on the selected functional unit, this being highly important if the wider aspects of sustainability such as food security are to be considered. However, there is statistical consistency across the tools regarding the ranking order of the farms in terms of their emissions.     

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.     

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.     

EFFICIENT COMPLIANCE WITH AGRICULTURAL NITRATE POLLUTION STANDARDS

Non-point pollutants such as nitrates are difficult to monitor and hence control. This paper considers nitrate abatement policies for the Tyne catchment in northern England. The analysis is based on an aggregate-level LP model which predicts producers' production decisions and estimates the resulting spatial distribution of nitrogen applications and nitrate emissions. The policy evaluation compares a catchment-level nitrate emission quota, a catchment-level nitrogen input quota and nitrogen input quotas targeted at individual land classes as alternative measures to achieve nitrate concentration standards. The results indicate that targeted nitrogen input quotas provide a feasible and relatively efficient abatement policy when a lack of information on individual farms prevents the use of the least cost emission tax.     

The Need for Comprehensive Climate Change Mitigation Policies in European Agriculture

During the last decade the European Union has shown a firm determination to move to a low carbon economy. Since 2008 the agricultural sector has been part of this strategy and is included in the EU effort sharing decision. Introducing specific GHG mitigation obligations for agriculture could be one option to achieve an overall GHG emission reduction target. One argument for this strategy would be that the agricultural sector is the main contributor of non‐CO₂ greenhouse gases. Nevertheless, a comprehensive EU mitigation policy would most likely have to take into account the particularities of its diverse agricultural sector, reflected by different trends in historical GHG emission reductions, and a varied mitigation cost structure between farming systems. Consequently, using targeted but flexible policy instruments may more equitably distribute the mitigation efforts across Member States and reduce cost inefficiencies. The increased uptake of technological and management emission mitigation measures would be crucial to keep mitigation costs for EU farmers at a minimum. However, while unilateral action would initially signal the EU's commitment to serious GHG mitigation effort in the sector, ultimately a multilateral agreement is needed to minimise emission leakage and to reduce global GHG emissions effectively.     

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.     

Where in the world is it cheapest to cut carbon emissions?*

Countries with low marginal costs of abating carbon emissions may have high total costs, and vice versa, for a given climate mitigation policy. This may help to explain different countries’ policy stances on climate mitigation. We hypothesize that, under a common percentage cut in emissions intensity relative to business as usual (BAU), countries with higher BAU emission intensities have lower marginal abatement costs, but total costs relative to output will be similar across countries, and under a common carbon price, relative total costs are higher in emission‐intensive countries. Using the results of the 22nd Energy Modeling Forum (EMF‐22), we estimate marginal abatement cost curves for the US, EU, China and India, which we use to estimate marginal and total costs of abatement under a number of policy options currently under international debate. This analysis provides support for our hypotheses, although its reliability is limited by the shortcomings of the EMF‐22 models and the degree to which our econometric model can adequately account for the substantial differences among them.     

Marginal Abatement Cost Curves for UK Agricultural Greenhouse Gas Emissions

This article addresses the challenge of developing a ‘bottom‐up’ marginal abatement cost curve (MACC) for greenhouse gas (GHG) emissions from UK agriculture. An MACC illustrates the costs of specific crop, soil and livestock abatement measures against a ‘business as usual’ scenario. The results indicate that in 2022 under a specific policy scenario, around 5.38 Mt CO₂ equivalent (e) could be abated at negative or zero cost. A further 17% of agricultural GHG emissions (7.85 Mt CO₂e) could be abated at a lower unit cost than the UK Government’s 2022 shadow price of carbon [£34 (tCO₂e)^?1]. The article discusses a range of methodological hurdles that complicate cost‐effectiveness appraisal of abatement in agriculture relative to other sectors.     

FINANCIAL STRESS AND CONSUMPTION EXPECTATIONS AMONG FARM HOUSEHOLDS: NEW ZEALAND'S EXPERIENCE WITH ECONOMIC LIBERALISATION

A review of New Zealand's experience with assistance to agriculture through the 1960s and 1970s and the subsequent deregulation of the sector in the mid-1980s provides background to this study. Data for sheep and beef farmers are used to elaborate the variety of financial changes in the boom and bust cycles that followed the policy changes. Changes in farm business stress are examined using some conventional financial ratios. New measures which partition household expenditure between consumption and investment are then developed. These better explain the stress experienced among farm households as a consequence of the readjustment process and provide insight to the impact of the legacy of debt, encouraged by government intervention, on farmers' current and expected household consumption over recent years. New Zealand's experience reveals that farm household consumption stress has been unevenly distributed. This suggests that policy concern, following the removal of government assistance to agriculture, should focus principally on the mitigation of the household distress caused by ongoing farm debt commitments.     

Greenhouse gas and groundwater recharge abatement benefits of tree crops in south-western Australian farming systems

The indirect benefits of a commercial tree crop for greenhouse gas and groundwater recharge abatement are analysed. Oil mallees are introduced into a whole-farm linear programming model as a source of income, an offset to greenhouse gas emissions from the mixed sheep and cropping enterprises and as a source of groundwater recharge abatement. The profitability of oil mallees is found to be very sensitive to the discount rate, yield and price assumptions and the relative profitability of other farm enterprises (especially the wool enterprise). Under standard assumptions where oil mallees are profitable, the trees significantly reduced greenhouse gas emissions and groundwater recharge and the farm remains profitable. If farm-level policies are introduced for greenhouse gas abatement, without tree crops or some other technological change, the current farming systems would fail and be replaced by alternative land uses.     

Are small‐scale rice farmers in eastern India really inefficient? Examining the effects of microtopography on technical efficiency estimates

The article analyzes how controlling for differences in land types (defined by position on a low‐scale toposequence) affects estimates of farm technical efficiency for rice farms in eastern India. Contrasting previous research, we find that farms are considerably more technically efficient when efficiency estimates are carried out at the plot level and control for plot characteristics rather than at the farm level without such controls. Estimates show farms cultivating modern varieties are technically efficient and plots planted with traditional varieties on less productive lands (upland and midupland) operate close to the production frontier. Significant technical inefficiency is found on more productive lands (medium and lowland plots) planted with traditional rice varieties. The finding that these smallholder rain‐fed rice farms are efficient cultivators on some plots contrasts with previous findings of farm‐level inefficiency (i.e., rejects overarching explanations linked to farm operator ignorance or lack of motivation) and suggests more complex explanations are required to address the inefficiency that is present.     

Brexit: How Will UK Agriculture Fare?

There is little doubt that Brexit would have significant implications for UK agriculture, a sector with strong trade links to the EU and strong reliance on CAP income support. This article reports preliminary results from employing a Computable General Equilibrium Model, a Partial Equilibrium Model and Farm Level Models to explore selected trade and domestic policy scenarios post‐Brexit. These allow for the estimation of changes in producer prices, production and farm incomes against a baseline scenario of continued EU membership. Under a Free Trade Agreement with the EU, agricultural impacts are relatively modest. By contrast, unilateral removal of import tariffs has significant negative impacts on prices, production and incomes. Adoption of the EU's WTO tariff schedule for all imports favours net importers (e.g. dairy) and harms net exporters (e.g. sheep). Given the strong dependence of most UK farms on direct payments, their removal worsens negative impacts of new trade arrangements and offsets positive impacts. Impacts vary across different types and sizes of farm, but also regionally. However, the period of adjustment to new trade and domestic policy conditions may prove very challenging for a large number of farm businesses.     

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.     

What’s next for the Renewable Energy Target – resolving Australia’s integration of energy and climate change policy?*

Australian climate change policy and its integration with Australia’s electricity markets have been fraught for at least two decades. The only enduring policy has been the Commonwealth Renewable Energy Target (RET). Despite the relative success of the RET in driving investment and reducing emissions, state governments have now pivoted towards contracts-for-difference (Cfds). In this article, we outline the issues associated with policy discontinuity and the large-scale RET and review its effectiveness as an emissions reduction tool and driver of electricity sector abatement. We find that the RET has been relatively successful across the key criteria of cost and emissions reductions and is a better policy instrument than contracts-for-difference, which are increasingly being adopted by state governments. Building on the work of Nelson et al. (2020), we propose a new approach, which would allow for continued use of Cfds but utilising the RET’s policy architecture.     

A LINEAR PROGRAMMING STUDY OF FAMILY-RUN DAIRY FARMS IN NORTHERN IRELAND

The paper presents the results of a study in which multiperiod linear programming models were used to examine the probable responses of small and medium sized dairy farms in Northern Ireland to various policy, farm indebtedness and development options and to project consequent structural change in the dairy sector. The introduction of quotas has curtailed the considerable potential for expansion of output on these farms while having a less detrimental effect on farm profits and the survival of the smaller dairy herd than the price cut necessary to produce the same reduction in output.     

Reducing nutrient loads from dairy farms: a bioeconomic model with endogenous feeding and land use

Growth trends of animal farming pose a threat to water quality around the world. To find cost‐efficient means to reduce nutrient loads from agriculture, detailed information on the abatement measures need to be incorporated in bioeconomic models. This study presents a theoretical framework that covers both animal and crop operations on farms. It describes the farmer decision making problem and incorporates nonlinear functions to capture the economic and biological aspects of the problem. The model is applied to Finnish dairy farms. The abatement cost functions are derived for nitrogen and phosphorus. Results indicate that abatement measures on fields should precede dietary changes.