Fraction of manure managed in each MMS type by region and species.
Source
Unverified. The values are a hardcoded tribble() in
generate_ipcc_tier2_params() in data-raw/livestock_coefficients.R,
annotated there "GLEAM 3.0 / FAO statistics (simplified)"; they are round
to the nearest 5 percentage points and match no table of the committed
GLEAM 3.0 Supplement S1 workbook, which carries no MMS shares. Unlike
gleam_mms_shares this object is result-affecting, through
.resolve_mms_shares(): it weights the Tier 2 manure CH4 methane
conversion factor (climate_mcf) and the Tier 1 manure direct-N2O
emission factor (ipcc_2019_n2o_ef_direct). It does not reach Tier 2
direct N2O, whose rows carry no region column and so take the pasture
EF3 for every stream (measured, whep#921).
The real shares are published in Supplement S1, Tables 4.2-4.11 of
FAO. 2018. GLEAM Model description, Version 2.0, Revision 5 (workbook
md5 72fd2ea477dfe8b30cd3657b2baa4af1, re-downloaded from FAO and
verified 2026-08-26; see gleam_mms_shares), per production system
(dairy / beef / feedlot cattle, dairy / non-dairy buffalo, small
ruminants, backyard / intermediate / industrial pigs, chickens) over the
10 GLEAM regions. Adopting them takes four choices that each move
numbers: collapsing the per-system tables onto species_gen, collapsing
GLEAM's regions onto the IPCC labels .add_ipcc_region() emits, deriving
the Global row GLEAM does not publish, and mapping GLEAM's richer MMS
vocabulary (Drylot, Pit storage, Burned for fuel, Uncovered anaerobic
lagoon) onto mms_type. Under one illustrative crosswalk (equal weights
throughout) on FAOSTAT 2020 head counts, whep#921 measured Tier 1 manure
direct N2O -11.1% (Buffalo -57%, Poultry +22%), Tier 1 manure CO2e
-4.2% and Tier 2 manure CH4 -26.9%. Treat as unverified until a
crosswalk is chosen.
Examples
regional_mms_distribution
#> # A tibble: 33 × 4
#> region species mms_type fraction
#> <chr> <chr> <chr> <dbl>
#> 1 North America Cattle Liquid/Slurry 0.4
#> 2 North America Cattle Solid Storage 0.3
#> 3 North America Cattle Pasture/Range/Paddock 0.25
#> 4 North America Cattle Daily Spread 0.05
#> 5 Western Europe Cattle Liquid/Slurry 0.35
#> 6 Western Europe Cattle Solid Storage 0.45
#> 7 Western Europe Cattle Pasture/Range/Paddock 0.15
#> 8 Western Europe Cattle Daily Spread 0.05
#> 9 Latin America Cattle Pasture/Range/Paddock 0.7
#> 10 Latin America Cattle Solid Storage 0.15
#> # ℹ 23 more rows