Greenhouse gas (GHG) assessment calculators have been created for a number of reasons, such as raising awareness of GHG emissions, reporting GHG emissions, project evaluation for change in GHG emissions, and market and product-oriented calculators designed to estimate GHG emissions per product (Colomb et al., 2013). The precision and ease of use of each calculator largely depend on the purpose of the calculator, e.g. there is more accountability for a calculator that is to be used in the carbon market than a calculator that is designed to raise awareness.
Generally, the aim of GHG assessment calculators can be divided into four distinctions:
Raising awareness. These calculators are the easiest to use with little or no training necessary. This also means that the accuracy of these calculators is the lowest of the four aims. Additionally, these calculators have limited scope and are not solution oriented.
Reporting. These calculators typically require some training and the aim is to describe and analyze situations in detail. Reporting GHG calculators can be developed for both farm- and landscape-level reporting. The results of these tools allow for comparisons between locations and different time periods. These calculators require much more information input than raising awareness of GHG calculators and are primarily designed to help inform decision-makers on adaptive policies. Additionally, these calculators serve as important tools for governments to report annual emissions to the IPCC.
Project evaluation. These GHG assessment calculators compare a business-as-usual scenario to an intervention scenario to assess specific project interventions. Project evaluation GHG calculators are divided into two subcategories depending on if the calculator has a carbon credit scheme orientation or otherwise.
Market- and product-oriented calculators. These GHG assessment calculators are used to calculate GHG per kg of the product rather than assessing a farm or landscape. The aim of these calculators is to compare GHG emissions of different products rather than locations.
Agriculture, forestry, and other land use (AFOLU) represent about 30% of total global GHG emissions (UNFCCC, 2012 cited in Colomb et al., 2013). AFOLU is of particular importance for low-income countries because more than half of low-income countries plan to decrease GHG emissions through reductions in AFOLU emissions (Richards et al., 2016). However, Richards et al. (2016) report that standard GHG calculators are only 60% accurate in low-income countries.
There are a number of GHG calculators with different aims currently available for agricultural use. More information for some popular GHG assessment calculators in agriculture can be accessed online:
Colorado State University’s Agriculture and Land Use National Greenhouse Gas Inventory Software (ALU): (http://www.nrel.colostate.edu/projects/ALUsoftware/)
CGIAR’s Climate Change Agriculture and Food Security Mitigation Options Tool for Agriculture (CCAFS-MOT): https://ccafs.cgiar.org/mitigation-option-tool-agriculture
Cool Farm Tool: https://www.coolfarmtool.org/
Food and Agriculture Organization of the United Nations Ex-Ante Carbon Balance Tool (EX-ACT): http://www.fao.org/tc/exact/ex-act-home/en/