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Climate change mitigation aims at stabilizing the greenhouse gas concentration in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. The Paris Agreement, in its Article 2 set this level to 2ºC.

According to the fifth assessment report of the IPCC, mitigation is defined as the “human intervention to reduce the sources or enhance the sinks of greenhouse gases” (IPCC, 2014b). In a broader approach, this definition can be extended to other pollutants and/or atmospheric components, such as black carbon particles, or albedo change due to land-use, all of which contribute to the climate change.

Mitigation results only refer to results from activities that would not have been implemented in the reference or baseline scenario, also called business-as-usual scenario. A baseline is the scenario likely to occur in the absence of any specific intervention to mitigate climate change. This concept is further developed in module C9.

A2 - 3.1.1 Key concepts

AFOLU and LULUCF

Agriculture, Forestry and Other Land Use (AFOLU) and Land Use, Land Use Change and Forestry (LULUCF) are categories of activities defined by IPCC in the context of emissions accounting. The AFOLU category includes LULUCF and Agriculture. In the context of mitigation, ‘Agriculture’ – in accordance with IPCC terminology – includes emissions from enteric fermentation, manure management, rice cultivation, prescribed burning of savannas and grassland, and from soils (i.e. agricultural emissions). Emissions related to forest and other land use are covered under LULUCF.

Indirect land-use change

Due to growing use of resources for humanity, for traditional land-use as well as biodiversity conservation and carbon sequestration, the amount of available arable land and forests is limited, and any land-based activity might cause a shift of land-use in another area. For example, conversion of gazing land to cropland could lead to deforestation to new grazing land elsewhere, to meet the demand for livestock production.

Indirect land-use change poses a major risk for the GHG mitigation. As in the above example, any deforestation caused by a CSA activity or policy, directly or indirectly, will result in high GHG emissions which are likely to more than cancel any GHG benefits of the project. It is therefore essential to avoid indirect land-use change or accurately estimate its effect. However, estimating the effect of land-use change can be complex, and it is easier to identify situations in which no indirect land-use change is expected.

Indirect land use change can be avoided if the previous use of the land is integrated with the CSA activity or policy, as is the case of intensification of existing production, or grazing combined with forestry on lands previously used only for grazing. Furthermore, the larger is the area considered, the more likely it is to capture the effect of any indirect land-use change. For this purpose, the evaluation of the GHG emissions and sequestration should be at least on national level, and should ideally include the area from which goods can be conveniently transported. However, considering the international nature of trade in globalized society, indirect land-use change is difficult to capture in a given area.

Double counting

If two policies – for instance one on mitigation (e.g. NAMA) and another one CSA specifically – affect the same geographical area and the same sources and sinks of GHG, it could be difficult to determine which part of the changes in GHG fluxes is to be attributed to which policy, and there is a risk that the entire mitigation outcome would be attributed to both policies, resulting in some of the mitigation outcome being counted twice. To prevent this risk, overlapping policies should be evaluated together as a package of policies. Alternatively, it should be determined in advance how the mitigation outcome be attributed to the policies. It is therefore important to define the scope and physical boundaries of policies to identify such risks of double counting.

To achieve climate change mitigation in the agricultural sectors, it is relevant to develop and implement a range of policies and measures that target all stages of the lifecycle of agricultural products. Module B10 elaborates further on this.

Demand side activities aim to modify the demand for agricultural products. This includes reducing losses in the food supply chain; changing human diets and cooking practices towards less emission intensive products; and reducing demand for wood and forestry products from unsustainably managed forests. 

Most agriculture related mitigation methodologies are supply side methodologies. There are many opportunities to mitigate greenhouse gas emissions during production, by reducing or avoiding greenhouse gas emissions.

Some demand and supply side approaches in agriculture aim to conserve resources to avoid emissions in the first place, while others focus on increasing carbon sequestration:

• Reducing/avoiding greenhouse gas emissions

This category includes policies and measures to reduce or avoid greenhouse gas emissions in the agriculture sectors, such as: improving soils management with conservation agriculture (i.e. no-tillage implemented in the context of varied crop rotations and soil protection/mulching), sustainable use of fertilizers and sustainable mechanization for crop production (see module B1); improving manure management and introducing livestock feed additives in livestock production (see module B2); conservation of forests and their sustainable management in the forestry sector (see module B3); using energy efficient aquaculture and reducing fossil fuel use by fishing fleets (see module B4); sustainably managing soils and lands and avoiding degradation of wetlands (see module B7.

This type of greenhouse gas emission reductions can be effectively evaluated using their emission intensity, rather than the absolute emissions, as these emissions are associated with agriculture products, whose availability is paramount to food security. This is also called relative decrease in greenhouse gas emissions. This rationale takes into consideration that increased production could lead to increased absolute emissions, but nonetheless the increased productivity leads to decreased emission intensity and to products with a lower greenhouse gas footprint. Recognizing the finite amount of produce required, this does lead to overall reduction in emissions.

• Removing greenhouse gas from the atmosphere

This category includes policies and measures to increase carbon sequestration in standing biomass and soils. Agro-ecosystems, including forests, naturally remove carbon dioxide from the atmosphere through photosynthesis. The sequestered carbon is stored in biomass and soils, thereby acting as “sinks”. Carbon capture in biomass and soils is generally cost-effective and with few or no associated direct risks, whereas artificial means of carbon capture and storage in subterranean carbon dioxide storage, currently explored, may be more hazardous, in the case of physical leakage or earthquake disturbance for instance. This type of greenhouse gas emission reductions is usually evaluated per area unit, e.g. tonnes of carbon sequestred (or removed from the atmosphere) per hectare per year.Beyond the climate change mitigation benefits, there are numerous other benefits from ecosystem services associated with increasing carbon sequestration in soils and biomass. Many contribute to improved agricultural productivity and climate change adaptation, thus being climate-smart. Improved grazing management can yield greater forage production, increase biodiversity and be a more efficient use of land resources (module B2). Reforestation can prevent soil erosion and provides numerous forest products (module B3).

• Reducing greenhouse gas outside the AFOLU sector and other effects

This category includes policies and measures which affect the agriculture sectors as well as other sectors, i.e. energy, industry and waste. It includes activities such as production of bioenergy (module B9), sustainably harvested wood for manufacturing and construction (module B3) and proper disposal of agriculture residues.

Furthermore, this category pertaining to the Agriculture, Forestry and Land-Use sector (AFOLU) includes policies and measures affecting climate change not through greenhouse gas, but rather by modifying the surface albedo or impacting regional climate, both of which can be achieved by afforestation (module B3).

Due to the complex nature of any intervention to implement CSA, assessing its impact and monitoring its effects can be complex. Monitoring is required to quantify the results, to ensure permanence of the mitigation effort, as well as to ensure there are no adverse effects elsewhere in the biosphere. To ensure effective monitoring, on top of all relevant GHG streams, major co-benefits and associated risks must be identified, and adequate monitoring scheme implemented. For example, if biomass is used to produce energy, on top of the land use and energetic use related parameters, it is also necessary to monitor water use and possible groundwater contamination, to ensure that water use is sustainable. Furthermore, the possibility of indirect land use change must also be investigated, as production of energy crops could compete with food production.

Mitigation in the AFOLU sector is measured following the IPCC methodology as detailed in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 2006). Three IPCC methodologies are relevant:

1. The generic IPCC methodology, which simply multiplies an activity data with an emission factor, resulting in GHG emissions or removals. The activity data, which measures the magnitude of the activity. This could be the affected land area, harvested wood volume, livestock population, amount of fertilizer used, waste management system specifications. The emission factor, which indicates the emissions, emission intensity or organic carbon stock associated with the policy or activity reviewed or their baseline scenario.
2. The gain and loss methodology, through which estimating the net carbon stock change of C pools as biomass, by adding all the gains and losses of carbon stock during the relevant time period. This methodology requires comprehensive inclusion of all carbon gains and losses to be effective. It is used for forestry projects as a default method.
3. The stock difference method, which estimates carbon stock change by comparing the carbon stock in two points in times, as for Soil carbon in mineral soils. The resulting carbon stock change is then divided by the considered time period, to result in an annual carbon stock change value. This methodology is usually used for non-forestry land use, such as cropland, and grassland, as well as for land use change. It is used for forest land in case a country exist of a national forest inventory with repeated measurements.

When applying the above methodologies, various activity data and emission factors are required. Whereas activity data always have to be measured, activity data can have several sources, categorised in three tiers.

Tier 1 approach implies using IPCC default emission factors, which are applicable world-wide. It is highly inaccurate, and is usually used only for rough estimation of the effect of a policy or activity. For a realistic estimation, for example for a national inventory, a higher tier approach is needed.

Tier 2 approach uses country specific emission factors, or even sub-regional emission factors, and applies them in the IPCC methodology. It is results is a better estimate of the GHG emissions and sequestration. The emission factors are either determined by a national measurement effort, which could be a survey, direct measurements or remote sensing analysis. Alternatively, it can be taken from recognized databases which collect verified emission factors. The relevant measurement approaches and existing databases are included in their respective chapters of this sourcebook.

Tier 3 approach uses methodologies and emission factors developed specifically for national circumstance. It is the most accurate approach for estimating GHG emissions and sequestration, but it requires effort to develop and maintain. The methodologies are not automatically transferable to other national circumstance, and therefore tier 3 approaches are not generally included in this publication for use by CSA policies and activities.

The AFOLU sector is important for the global GHG mitigation strategy, as it encompasses many cost-effective means of mitigation. When considering cost-effective mitigation potential, it should be known at what net cost the mitigation action can be implemented. Considering this, the combination of forestry and agriculture are estimated to have a potential for mitigating 3 GtCO₂ per year with a carbon price at 20 USD/tCO₂, and 7 GtCO₂ per year at 100 USD/tCO₂. Production efficiency worldwide has been improving in recent years, and implementation of CSA could further reduce net emission intensity of AFOLU commodities. The mitigation potential for the AFOLU sector is further described in Figure A2.6 hereinafter.

Each region has different potential, depending on its geographic and climatic conditions as well as the socio-economic situation and the production taking place in it. When designing interventions following a CSA approach, activities relevant in the region and with low net cost of implementation should be pursued by seizing local opportunities and co-benefits, to ensure climate-smart agriculture with effective and cost-effective mitigation impact. For instance, according to the IPCC’s fifth assessment report, for the forestry sector (discussed in module B3), reduced deforestation is most effective in Latin America, Central Africa and the insular Asia, whereas in continental Asia and in Northern Africa have the highest potential for afforestation and reforestation, and in the OECD countries forest management would be more effective (Smith et al., 2014). Also, rice management (explained in module B1) is a relevant activity almost exclusively in Asia, whereas grazing land management (addressed in module B7 on sustainable soil management and module B2 on livestock production) is relevant almost in any context.

When considering mitigation potential, it should be known at what net cost the mitigation action can be implemented. Mitigation costs vary largely between agriculture commodities and also depend on country contexts such as production, production potential, demand and lifestyle. When considering the cost of implementation in terms of mitigation, the various costs and financial benefits throughout the production chain, such as implementation of the action, increase/decrease in resource needs (soil, water, fertilisers, additives, fuel) and sources of income, are added and divided by the expected emission reductions, to get an estimate of the cost it would take to mitigate emission of one tonne CO₂ eq. 

As a general remark, the agriculture sectors are important for the countries’ greenhouse gas mitigation strategies, as they encompass many cost-effective means of mitigation. Specifically, to ensure an optimal mitigation outcome, countries may choose to focus climate change mitigation efforts on the agriculture sectors that contribute most to national greenhouse gas emissions and for which large mitigation potential has been identified. 

Mitigation costs vary largely between AFOLU commodities. For example, in rice and cereal production, mitigation cost is around 25 USD/tCO₂, 110 USD/tCO₂, for cattle meat production and as high as 330 USD/tCO₂ for milk production. Mitigation activities in forestry might be cost effective without financial support.