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Build the livestock greenhouse-gas emissions extension.

Source: R/livestock_ghg_extension.R
build_livestock_ghg_extension.Rd

Aggregate per-animal IPCC livestock emissions into a footprint extension keyed by (year, area_code, item_cbs_code), expressed in kilograms of carbon-dioxide equivalent (CO2e). This bridges the cohort-level emissions pipeline (calculate_livestock_emissions()) to the input-output grain used by build_io_model() and compute_footprint(), exactly like build_grassland_land_extension() does for land.

Live-animal head counts come from get_primary_production(), are bridged to IPCC species with prepare_livestock_emissions(), and the resulting enteric and manure emissions are converted to CO2e and summed back to the live-animal commodity sector (item_cbs_code, e.g. 961 for non-dairy cattle), which is itself a sector in build_io_model().

Two IPCC tiers are available, selected with tier:

  • 1 (default): Tier 1 regional emission factors (IPCC 2019). It needs only species, country and head counts, so it is complete for every country in get_primary_production(). It covers enteric and manure methane and manure N2O (direct and indirect, from default per-head nitrogen excretion rates).

  • 2: Tier 2 cohort energy balance (IPCC 2019). It derives enteric CH4 and manure N2O from a per-animal energy and nitrogen balance, for finer resolution, but requires cohort weight and diet inputs. Animals whose emissions cannot be resolved (missing diet or energy data) are dropped with a warning rather than entering the footprint as NA. Its per-head enteric and manure emissions now sit in the same range as the Tier 1 regional factors. Tier 1 remains the default because it is complete for every country in get_primary_production(), whereas Tier 2 needs cohort and diet inputs.

The CO2e conversion uses 100-year global warming potentials selected with gwp:

  • "ar6" (default): IPCC AR6 (2021) Table 7.15, biogenic CH4 = 27, N2O = 273.

  • "ar5": IPCC AR5 (2013), CH4 = 28, N2O = 265 (no climate-carbon feedback).

  • "ar4": IPCC AR4 (2007), CH4 = 25, N2O = 298.

Usage

build_livestock_ghg_extension(
  tier = 1,
  gwp = c("ar6", "ar5", "ar4"),
  data = list(),
  example = FALSE
)

Arguments

tier

IPCC tier, 1 (default) or 2.

gwp

100-year global warming potential standard, "ar6" (default), "ar5" or "ar4".

data

Optional named list of pre-loaded inputs to avoid remote reads: primary_prod (the get_primary_production() output). It falls back to its reader when absent.

example

If TRUE, return a small fixture instead of reading remote data. Defaults to FALSE.

Value

A tibble with columns year, area_code, item_cbs_code, impact_u (livestock emissions in kilograms CO2e) and method_ghg (the chosen tier and GWP standard, e.g. "IPCC_2019_Tier1_AR6").

Examples

build_livestock_ghg_extension(example = TRUE)
#> # A tibble: 6 × 5
#>    year area_code item_cbs_code   impact_u method_ghg         
#>   <int>     <int>         <int>      <dbl> <chr>              
#> 1  1986        10           960  615600000 IPCC_2019_Tier1_AR6
#> 2  1986        10           961 3078000000 IPCC_2019_Tier1_AR6
#> 3  1986        10           976 1105650000 IPCC_2019_Tier1_AR6
#> 4  1986       100           961 2246400000 IPCC_2019_Tier1_AR6
#> 5  1987        10           961 3108780000 IPCC_2019_Tier1_AR6
#> 6  1987       100           960  842400000 IPCC_2019_Tier1_AR6