Four LUC calculation methods are implemented in the LUC Impact tool:

1. "Previous land use known",
2. "Previous land use unknown, country known",
3. "Previous land use unknown, country unknown", 
4. "Carbon opportunity cost".

Three amortization methods are offered in the LUC Impact Tool:

1. "Equal amortization (in line with PAS 2050)",
2. "Equal amortization (in line with GHG protocol)", 
3. "Linear amortization (in line with SBTi-FLAG guidances and GHG protocol)".

They are available for the two calculation methods "Previous land use unknown, country known" and "Previous lands use unknown, country unknown". 

Methodology of the calculation is explained in detail in the PAS 2050:2012 (the standard is specific for horticulture, but the dLUC calculation applies to all crops).
Procedure to calculate emissions from dLUC:

1. Expansion and contraction of forest and grassland per country (as defined in PAS 2050) are based on FAO land occupation change in 20 years.
2. Expansion and contraction of specific crop is based on FAO harvested area change in 20 years. Cropland is either classified as perennial or annual cropland.
3. For each crop: transformation in hectares from forest, grassland, perennial crop and annual crop is calculated.
   a. The weighted average takes into account relative differences in crop expansion at the expense of forest, grassland, annual/perennial based on the expansion/contraction of forest, grassland and cropland. 
   b. The normal average is a simple average of these options (all 1/3). 
   c. All results are scaled to the relative amount of expansion of the crop. This is described in PAS 2050.
4. Based on worldwide climate and soil types provided by EU, climate zone and soil types are selected which are representable for the country. With this, carbon stock can be calculated. For forest land, specific biomass is obtained per country from the Global forest resources assessment 2020. For grassland, biomass is derived from continent and climate condition (based on European commission data and IPCC values). Soil carbon content is based on IPCC 2019 soil carbon defaults for climate regions and soil types, stock change factors from IPCC 2019 are used to calculate the soil carbon stock for different land use and land management practices. Biomass of crops is obtained from either the IPCC or PAS 2050, one value represents all annual crops and another all perennial crops.
5. Change in carbon stock between previous and current land use is multiplied with 44/12 to obtain kg CO2. This is divided equally over 20 years (multiplied with 1/20).
6. The crop yield is derived from FAOSTAT and determines impact per kg product.

The carbon stock will depend on the country in analysis.  

Basically, the carbon stock takes into consideration the carbon vegetation (Cveg), which is composed of below- and above- ground carbon stock and soil organic carbon. In our LUC model, to assess the carbon stock, we consider:

1. Carbon vegetation (Cveg): it takes into account values adapted from Table 11 of the European Commission decision and the values depend on continent, climate and if crop is perennial or annual. (If the country has different types of climate, we take into account the two most prevalent).  
2. Soil organic carbon (SOC): it takes into account values from Table 2.3 from IPCC 2006 (no refinements in IPCC 2019 refinements) Volume 4, which also depends on climate and soil type. For soil organic carbon, we need to know the specific country (see table).
3. Once the carbon vegetation and soil organic carbon is summed up, we multiply by stock change factor (Table 5.5, IPCC 2019 refinements, Volume 4). The values depend on management type and climate. 

Indeed, this transformation does not lead to a carbon stock difference, and so results in 0 kg CO₂ eq. This is because we do not differentiate the carbon stock of different annual crops. Both the soil carbon stock and the vegetation carbon stock are the same for all annual crops.

• Weighted average: conversions of forestland to cropland and grassland to cropland and conversions between annual and perennial cropland are based on statistics of expansion/contraction of forestland, grassland and annual/perennial cropland. The exact calculation method is described in the PAS 2050-1:2012 (horticulture), in section 5.2.3.3 “Assessment of average GHG emissions from land use change when the previous land use is not known”.
• Normal average: conversion of forestland to cropland and grassland to cropland and conversions between annual and perennial cropland are all set to 1/3rd of the converted area. This means that a normal average of the emissions related to each of the three types of conversions is taken. This is also described in the PAS 2050.
• Worst case is the highest of the two above. It is prescribed by the PAS 2050 to take the highest of these two calculation methods.

In the LUC methodology, we account for LUC over a period of 20 years. If the certificate guarantees that no land has been converted for 20 years, then you could set the LUC emissions to zero. The tool does not consider any indirect market effects. In case the certificate stretches a shorter period of time, one could actually still use the result from the LUC tool for the greenhouse gas calculation, to get insights from it.

For Grassland we use the FAO land use category: “Land under perm. meadows and pastures”, which refers to land used permanently (five years or more) to grow herbaceous forage crops, either cultivated or growing wild (wild prairie or grazing land).

These are the FAO items used for forest and grassland:
Item, FAO Item, FAO Element
Land under perm. meadows and pastures, 6655, 5110
Forest land, 6646, 5110
In addition, for each crop and country, we use FAO data from “Crops and livestock products”: area harvested over the last 20 years.

In the LUC dataset, figures are provided per crop-country combination. If the feed composition is known, than the LUC emissions related to animal products can be calculated. Our LCI database: Agri-footprint contains information on representative feed composition for several animal production systems in different countries in the world, therefore Agri-footprint is the best source of LUC emissions for animal products.

Since the LUC Impact dataset is developed based on FAO data, the cut off time is (the year of the most recent FAO data - 20 years). For example, if the most recent FAO data is from 2020, then the cut off time is 2000. 
We use the three-year average to calculate impact results. For example, if the cut off time is year 2000, then the results in that year is actually a three-year average of 2000, 2001, and 2002.

The change in values in different versions is due to the update in FAO data. Sometimes FAO updates the historical data together with the new data release. LUC Impact dataset is always calculated with the latest FAO data. Therefore, changes in this source will result in value changes in the dataset.

There are two options in the LUC Impact tool: according to IPCC Assessment Report 5 - GWP100 including CCF, N₂O = 298 kg CO2eq; according to IPCC Assessment Report 6, N₂O = 273 kg CO₂ eq.

Emissions from oxidation and mineralization of peatland due to anthropogenic use are not included in the emissions of the LUC tool or dataset, not in version 2022 and not in previous versions. The soil carbon loss (and associated nitrogen mineralization) is included for mineral soils only.

When this tool was build in the past, we decided to have a conservative approach and set results to 0 when sequestration occurs. There is an option to choose negative values in the web-based LUC Impact tool.

The LUC Impact tool allows for calculation of the land use change impact in three methods as described in the first question above. More specifically:

1. Country known & previous land use unknown: this approach is described in the PAS 2050-1 published by BSI and is made operational in the tool using various FAO and IPCC data sources. The calculation is based on statistics on country level for the expansion and contraction of forestland, grassland, annual cropland and perennial cropland (FAO). The specific land use change for a crop is based on national statistics on the relative expansion of that crop (FAOSTAT). You need to provide the country of crop cultivation and the crop.
2. Country & previous land use unknown: a weighted average is determined based on FAO statistics, using the same methodology as in ‘country know & land use unknown’ for calculating the GHG emissions for each relevant country. For this one you only provide the crop.
3. Country & previous land use known: In case the country and both the current and the previous land use is known, the carbon stock change is calculated using IPCC defaults. For this functionality you need to provide: country, crop, climate type, soil type, tillage intensity, current cultivation input level and the previous vegetation type (or manually enter the carbon vegetation stock). All these parameters are based on the IPCC 2019 refinements or IPCC terminology.

The LUC Impact dataset simply contains the final results for all crop-country combinations with the combination “country known, previous land-use unknown” (scenario 1 above).

No. Since it's based on FAO data so there is no animal production system included. However, if the client would know the feed formulation and quantity of the animals, then they could calculate LUC emissions from feed for the animal production systems. This would be difficult for processed feeds, however. In that case it would be easier to purchase the Excel results of Agri-footprint database, there LUC is also separately noted.

LUC from grazing is unfortunately not represented in the LUC tool and dataset. We are working on overcoming the data gaps that now inhibit us from calculating LUC for grazing, and hope to be able to include this in a future version of the tool and dataset. At this point, only LUC from feed would be considered. In Agri-footprint we made a rough assumption for LUC related to grazing land, so the client would be able to obtain this via a license for Agri-footprint.

We aim for an update every one or two years.

Yes, we document our methodology and modelling choice when developing this tool. You can find the methodology report on the LUC Impact webpage.