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.     

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.     

Does carbon farming provide a cost‐effective option to mitigate GHG emissions? Evidence from China

In this study, we apply a whole farm bioeconomic analysis to explore the changes in land use, farm practices and on‐farm greenhouse gas (GHG) emission under varying levels of agricultural greenhouse gas abatement incentives in the form of a carbon tax for a semi‐arid crop‐livestock farming system in China's Loess Plateau. Our results show that the optimised agricultural enterprises move towards being cropping‐dominated reducing on‐farm emission since livestock perform is the major source of emission. Farmers employ less oats‐based and rapeseed‐based rotations but more dry pea‐based rotations in the optimal enterprise mix. A substantial reduction in on‐farm greenhouse gas emission can be achieved at low cost with a small increase in carbon incentives. Our estimates indicate that crop‐livestock farmers in China's Loess Plateau may reduce their on‐farm GHG emission between 16.6 and 33 per cent with marginal abatement costs <￥100/t CO₂e and ￥150/t CO₂e in 2015 Chinese Yuan. The analysis implies that reducing greenhouse gas emission in China's semi‐arid crop‐livestock agriculture is potentially a low‐cost option.     

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.     

Agriculture's Likely Role in Meeting Canada's Kyoto Commitments*

Voluntary adoption of beneficial management practices will be the primary means by which farmers cut net greenhouse gas (GHG) emissions. The offset system will not be a major driver due to (a) the relatively low prices likely to be offered by large final emitters facing an emission cap, (b) discounts applied to those prices for temporary sequestration, (c) the transaction costs and risk premiums associated with signing carbon contracts, and (d) the low elasticity of supply of CO₂ abatement. Although Canadian farmers are likely to participate to only a limited extent in the carbon‐offset market, many will find it profitable to adopt one or more of the BMPs for reducing net GHG emissions. Canadian agriculture is likely to contribute significantly to net emission reductions by voluntarily sequestering carbon due to the adoption of zero till in the last decade, and possibly by cutting fertilizer levels in the next decade. The contribution will be mainly a response to meeting personal economic objectives rather than being induced by direct incentives through the offset program.     

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.     

Competition for land in the global bioeconomy

The global land use implications of biofuel expansion have received considerable attention in the literature over the past decade. Model‐based estimates of the emissions from cropland expansion have been used to assess the environmental impacts of biofuel policies. And integrated assessment models have estimated the potential for biofuels to contribute to greenhouse gas (GHG) abatement over the coming century. All of these studies feature, explicitly or implicitly, competition between biofuel feed stocks and other land uses. However, the economic mechanisms governing this competition, as well as the contribution of biofuels to global land use change, have not received the close scrutiny that they deserve. The purpose of this article is to offer a deeper look at these factors. We begin with a comparative static analysis which assesses the impact of exogenously specified forecasts of biofuel expansion over the period: 2006–2035. Global land use change is decomposed according to the three key margins of economic response: extensive supply, intensive supply, and demand. Under the International Energy Agency's “New Policies” scenario, biofuels account for nearly one‐fifth of global land use change over the 2006–2035 period. The article also offers a comparative dynamic analysis which determines the optimal path for first and second generation biofuels over the course of the entire 21st century. In the absence of GHG regulation, the welfare‐maximizing path for global land use, in the face of 3% annual growth in oil prices, allocates 225 Mha to biofuel feed stocks by 2100, with the associated biofuels accounting for about 30% of global liquid fuel consumption. This area expansion is somewhat diminished by expected climate change impacts on agriculture, while it is significantly increased by an aggressive GHG emissions target and by advances in conversion efficiency of second generation biofuels.     

Mitigation potential and costs for global agricultural greenhouse gas emissions1

Agricultural activities are a substantial contributor to global greenhouse gas (GHG) emissions, accounting for about 58% of the world's anthropogenic non‐carbon dioxide GHG emissions and 14% of all anthropogenic GHG emissions, and agriculture is often viewed as a potential source of relatively low‐cost emissions reductions. We estimate the costs of GHG mitigation for 36 world agricultural regions for the 2000–2020 period, taking into account net GHG reductions, yield effects, livestock productivity effects, commodity prices, labor requirements, and capital costs where appropriate. For croplands and rice cultivation, we use biophysical, process‐based models (DAYCENT and DNDC) to capture the net GHG and yield effects of baseline and mitigation scenarios for different world regions. For the livestock sector, we use information from the literature on key mitigation options and apply the mitigation options to emission baselines compiled by EPA.     

Logs or permits? Forestry land use decisions in an emissions trading scheme

Negative carbon emissions options are required to meet long-term climate goals in many countries. One way to incentivise these options is by paying farmers for carbon sequestered by forests through an emissions trading scheme (ETS). New Zealand has a comprehensive ETS, which includes incentives for farmers to plant permanent exotic forests. This research uses an economy-wide model, a forestry model and land use change functions to measure the expected proportion of farmers with trees at harvesting age that will change land use from production to permanent forests in New Zealand from 2014 to 2050. We also estimate the impacts on carbon sequestration, the carbon price, gross emissions, GDP and welfare. When there is forestry land use change, the results indicate that the responsiveness of land owners to the carbon price has a measured impact on carbon sequestration. For example, under the fastest land use change scenario, carbon sequestration reaches 29.93 Mt CO₂e by 2050 compared to 23.41 Mt CO₂e in the no land use change scenario (a 28% increase). Even under the slowest land use change scenario, carbon sequestration is 25.89 Mt CO₂e by 2050 (an 11% increase compared with no land use change). This is because, if foresters decide not to switch to permanent forests in 1 year, carbon prices and ultimately incentives to convert to permanent forests will be higher in future years.     

The influence of crediting and permanence periods on Australian forest-based carbon offset supply

Governments globally are developing increasingly ambitious carbon emissions reduction schemes that include significant emissions offset credits for forest-based carbon sequestration. Such strategies can present significant challenges in highly modified and intensively farmed regions where forest land use opportunity and establishment costs are high. This article evaluates the economics of land-use change via active afforestation for local carbon abatement in the Australian state of South Australia, a region with high supply costs representative of long-established temperate farming regions. We found that there is no economically viable abatement below $38 tCO₂e⁻¹, however up to 154 Mt CO₂e of abatement could be available up to prices of $50 tCO₂e⁻¹.Variation in current Australian Emissions Reduction Fund (ERF) policy parameters related to permanence and crediting periods were also assessed. Recent ERF contracts involve a 100-year land-use change commitment (permanence period) and a 25-year crediting period where payments for growth in carbon from the land-use change is contracted. We compared outcomes of this arrangement to a scenario with equal 100-year permanence and crediting periods. We found substantial differences in carbon supply at some price points for a 25 rather than a 100-year crediting period. Under ERF parameters the first economically viable revegetation options occur at $42 tCO₂e⁻¹, however, we found a 69 percent reduction in economically viable supply at a carbon price of $50 tCO₂e⁻¹. The results highlight the role offset crediting policy can have on dis-incentivising land-use change and the need for landholders to be compensated fully for temporal opportunity costs.     

Developing farm-specific marginal abatement cost curves: Cost-effective greenhouse gas mitigation opportunities in sheep farming systems

Growing demand for agricultural produce, coupled with ambitious targets for greenhouse gas emissions reduction present the scientific, policy and agricultural sectors with a substantial mitigation challenge. Identification and implementation of suitable mitigation measures is driven by both the measures’ effectiveness and cost of implementation. Marginal abatement cost curves (MACCs) provide a simple graphical representation of the abatement potential and cost-effectiveness of mitigation measures to aid policy decision-making. Accounting for heterogeneity in farm conditions and subsequent abatement potentials in mitigation policy is problematic, and may be aided by the development of tailored MACCs. Robust MACC development is currently lacking for mitigation measures appropriate to sheep systems. This study constructed farm-specific MACCs for a lowland, upland and hill sheep farm in the UK. The stand-alone mitigation potential of six measures was modelled, against real farm baselines, according to assumed impacts on emissions and productivity. The MACCs revealed the potential for negative cost emissions’ abatement in the sheep industry. Improving ewe nutrition to increase lamb survival offered considerable abatement potential at a negative cost to the farmers across all farms while, lambing as yearlings offered negative cost abatement potential on lowland and upland farms. The results broadly advocate maximising lamb output from existing inputs on all farm categories, and highlight the importance of productivity and efficiency as influential drivers of emissions abatement in the sector. The abatement potentials and marginal costs of other measures (e.g. reducing mineral fertiliser use and selecting pasture plants bred to minimise dietary nitrogen losses) varied between farms, and this heterogeneity was more frequently attributable to differences in individual farm management than land classification. This has important implications for the high level policy sector as no two farms are likely to benefit from a generic one size fits all approach to mitigation. The construction of further case-study farm MACCs under varying farm conditions is required to define the biophysical and management conditions that each measure is most suited to, generating a more tailored set of sector-specific mitigation parameters.     

A grassland strategy for farming systems in Europe to mitigate GHG emissions—An integrated spatially differentiated modelling approach

This paper assesses the impact of an EU-wide policy to expand grassland areas and promote carbon sequestration in soils. We use the economic Common Agricultural Policy Regionalized Impact (CAPRI) model, which represents EU agriculture using 2450 mathematical programming farm-type models in combination with the biogeochemistry CENTURY model, which provides carbon sequestration rates at a high resolution level. Both models are linked at the NUTS3 level using location information from the Farm Accounting Data Network. We simulated a flexible grassland premium such that farmers voluntary and cost efficiently increase grassland area by 5%. We find that the GHG mitigation potential and the costs depend on carbon sequestration rates, land markets and induced land use changes, and regional agricultural production structures. In Europe, the calculated net effect of converting 2.9 Mha into grassland is a reduction of 4.3 Mt CO2e (equivalents). The premium amounts to an average of EUR 238/ha, with a total cost of EUR 417 million for the whole EU. The net abatement costs are based on the premium payments, and account on average EUR 97/t CO2e. However, substantial carbon sequestration (28% of total sequestration) can be achieved at a rate of EUR 50/t CO2e. Carbon sequestration would be most effective in regions of France and Italy and in Spain, the Netherlands and Germany. Larger farms and farm-types specialized in ‘cereals and protein crops’, ‘mixed field cropping’ and ‘mixed crop-livestock’ farming systems have the highest mitigation potential at relatively low costs.     

Making explicit agricultural ecosystem service trade-offs: a case study of an English lowland arable farm

European farmland hosts a species assemblage of animals and plants which have undergone declines through the late twentieth and early twenty-first centuries, at least partly as a result of increased productivity. Further increases in human populations, changes in availability and cost of raw materials, policy constraints, price volatility and climatic changes will further drive greater efficiency and high yields in agriculture, with the risk of further adverse environmental impacts. We assess the effects of different management priorities (production-driven cropping vs. wildlife-friendly farming) at an arable farm in eastern England on food production, greenhouse gas (GHG) emissions and biodiversity. We modelled one actual and three alternative cropping scenarios using actual yields from the farm over 13 years, to calculate total yields and those foregone for agri-environmental measures. We measured crop yields, relative abundance of 19 farmland bird species, and CO₂ and N₂O emissions related to crop production. Removing up to 10.5% of land from production coupled with a more diverse rotation (including legumes) resulted in a large increase in breeding birds (177%) and reduction of 9.4% in GHG emissions at the cost of 9.6% of food energy. Food protein lost was only 2.9%. A smaller increase in bird numbers of 50% could be achieved at a much smaller cost to yield (～1.7% energy or protein) but with correspondingly smaller emissions reductions (1.2%). Results are discussed within the context of continued biodiversity loss to agriculture, increasing food demand and changing diets.     

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.     

Allocating provincial CO2 quotas for the Chinese national carbon program

In order to improve the efficiency of climate change initiatives China launched its national carbon market in December 2017. Initial CO2 quota allocations are a matter of significant concern. How should we allocate CO₂ emissions reduction responsibilities among Chinese provinces, assuming that provinces will not or cannot trade these responsibilities among themselves? In this paper, we allocate CO₂ quota from the perspective of cost minimisation. First, we estimate the national CO₂ marginal abatement cost (MAC) function and deduce the interprovincial MAC functions. Second, we build an allocation model with nonlinear programming for cost minimisation. Finally, we obtain the allocation results under the emissions reduction target by 2030. The results are as follows. (i) The national MAC was 134.3 Yuan/t (at the constant price of 1978) in 2011, with an overall upward trend from 1990 to 2011. (ii) The interprovincial MACs differ significantly and decline gradually from east to west. Hebei has the largest emissions reduction quota, and Shandong has the largest emissions quota by 2030. (iii) Compared with other criteria of per capita, gross domestic product (GDP), grandfathering and carbon intensity, the proposed approach is the most cost‐effective in achieving the reduction target, with cost savings of 37.7, 34.5, 47.9 and 33.87 per cent, respectively.     

‘Deal’ or ‘No Deal’? Impacts of Alternative Post‐Brexit Trade Agreements on UK Agriculture

Brexit will have important implications for UK agricultural commodity markets due to potentially significant changes to trade flows. We quantify the sectoral impacts on UK agriculture of three illustrative scenarios, which capture a broad range of potential trade arrangements: Bespoke Free Trade Deal , WTO Default and Unilateral Trade Liberalisation . It is estimated that the projected market impacts are relatively small if the UK negotiates a Bespoke Free Trade Agreement with the EU. The projected impacts are much greater under the two other scenarios, which capture potential trade arrangements if ‘no deal’ is reached. The high tariffs imposed under the WTO default scenario lead to significant adjustments in trade between the UK and EU‐27, with the impact on the domestic UK market depending on whether the UK is a net importer or a net exporter of the relevant commodity. All sectors experience price and production declines under the trade liberalisation scenario in which the UK unilaterally sets tariffs on imports from both the EU‐27 and the rest of the world to zero; the impacts are particularly severe in the beef and sheep sectors where international competition is very strong.     

Climate change: scenarios,impacts, policy,and development opportunities

This article is divided into three parts. First, it provides an overview of the main outcomes of the last IPCC assessment report, both in terms of economic drivers of greenhouse gas (GHG) emissions, and in terms of impacts of climate change, in particular for the agriculture sector. Then, it focuses on policy options and their optimal design, taking into account technological availability, international cooperation, and above all the stringency of the remaining carbon budget. Finally, it analyzes the size and direction of investment decisions required to stabilize GHG emissions and their implications for economic development.     

The importance of ‘extremely unlikely’ events: tail risk and the costs of climate change

In assessing the risks associated with climate change, ‘tail risks’ (low‐probability extreme events) often play a much larger role than their probability alone might indicate. There are three main reasons for this: the linear relationship between sensitivity and warming; the convexity of the damage function; and the concavity of the utility function. Ignoring the upper tail of the distribution of possible outcomes will result in serious underestimates of the social cost of carbon dioxide (CO₂) emissions and of the socially optimal price for emissions.     

Climate change: a rational choice politics view*

Reduction in carbon dioxide emissions constitutes a global public good; and hence there will be strong incentives for countries to free ride in the provision of CO₂ emission reductions. In the absence of more or less binding international agreements, we would expect carbon emissions to be seriously excessive, and climate change problems to be unsolvable. Against this obvious general point, we observe many countries acting unilaterally to introduce carbon emission policies. That is itself an explanatory puzzle, and a source of possible hope. Both aspects are matters of ‘how politics works’– i.e. ‘public choice’ problems are central. The object of this paper is to explain the phenomenon of unilateral policy action and to evaluate the grounds for ‘hope’. One aspect of the explanation lies in the construction of policy instruments that redistribute strategically in favour of relevant interests. Another is the ‘expressive’ nature of voting and the expressive value of environmental concerns. Both elements – elite interests and popular (expressive) opinion – are quasi‐constraints on politically viable policy. However, the nature of expressive concerns is such that significant reductions in real GDP are probably not sustainable in the long term – which suggests that much of the CO₂ reduction action will be limited to modest reductions of a largely token character. In that sense, the grounds for hope are, although not non‐existent, decidedly thin.     

Increasing agricultural productivity while reducing greenhouse gas emissions in sub‐Saharan Africa: myth or reality?

The motivation for this study stems from two major concerns that are interlinked. The first is the decades long food insecurity crisis faced by sub‐Saharan African (SSA) countries which is still prevalent. The second is the negative impact greenhouse gas (GHG) emissions from agriculture may have on future food production and which is likely to worsen the food insecurity problem. The conundrum SSA farmers face is how to increase food output through productivity growth while minimizing GHG emissions. To measure changes in productivity growth and GHG emissions, this study evaluates the agricultural performance of 18 SSA countries by utilizing the Malmquist–Luenberger index to incorporate good and bad outputs for the years 1980–2012. The empirical evidence demonstrates that productivity is overestimated when bad outputs are not considered in the production model. The analysis provides a better understanding of the effectiveness of previous mitigation methods and which informs an appropriate course of action needed to achieve the twin objectives of increasing agriculture productivity while reducing GHG emissions.