Methane conversion factors transcribed from Table 10.17 of each IPCC
edition, over the same mms_type / climate_zone key space as
climate_mcf so that either can be substituted for it. Selected with the
mcf_source manure-engine option (see manure_engine_options). Since
whep#1022 the edition == "ipcc_2019" rows are the default: the 2019
Refinement is the current IPCC guidance, and the six cells of
climate_mcf whose provenance could not be established should not be what
ships. climate_mcf stays reachable as mcf_source = "as_shipped" so an
older run can be reproduced.
Six cells of climate_mcf match no published IPCC value, and three of the
mms_type labels that carry them – dry lot, the two composting rows and
the anaerobic digester – are unreachable on the live Tier 2 path, because
regional_mms_distribution routes manure to only six systems and none of
them is one of those. The cells that are live and edition-dependent are
pasture/range/paddock, liquid/slurry and the anaerobic lagoon, and it is
those three that the default change moves.
Format
A tibble with columns:
- edition
"ipcc_2006"or"ipcc_2019", the two values themcf_sourceoption takes.- mms_type
Manure-management system, in the climate_mcf vocabulary, plus the six 2019 anaerobic-digester classes.
- climate_zone
"Cool","Temperate"or"Warm".- mcf_percent
Methane conversion factor (percent of
Boachieved).NAwhere the edition publishes no default – the 2006 anaerobic digester, which is "0-100 percent, calculate".- paired_bo_m3_kg_vs
The methane potential (
Bo, m3 CH4 per kg volatile solids) the edition publishes this MCF together with, orNAwhere it publishes none and the animal-categoryBoof ipcc_tier2_bo_values applies. Only the three 2019 pasture/range/paddock rows carry one, 0.19 (whep#1137).
Source
IPCC. 2006. 2006 IPCC Guidelines for National Greenhouse Gas
Inventories, Vol 4, Ch 10, Table 10.17 "MCF values by temperature for
manure management systems", pp. 10.44-10.47 (PDF md5
97b97e8d0e4ca101c77fac2d63a0cb86).
IPCC. 2019. 2019 Refinement to the 2006 IPCC Guidelines for National
Greenhouse Gas Inventories, Vol 4, Ch 10, Table 10.17 (Updated)
"Methane conversion factors for manure management systems",
pp. 10.68-10.70 (PDF md5 c1784e747af9bb307e93f4170c12679a).
Both PDFs re-downloaded from ipcc-nggip.iges.or.jp and checksummed on
2026-09-08. Every cell here was read off them; the collapse rules above
are the only step that is not a transcription.
Collapse rules
Neither edition publishes exactly three numbers for every system, so two collapse rules are applied. Both are WHEP choices, stated here because they are not IPCC statements – and because the 2019 edition is now the default, the second of them is live on every Tier 2 run:
2006 per-degree rows (liquid/slurry, uncovered anaerobic lagoon) are read at the middle column of each temperature class. Table 10.15 of the same chapter defines the classes as Cool below 15 C, Temperate 15 to 25 C and Warm above 25 C, and Table 10.17 groups its 19 per-degree columns the same way, so the middle columns are 12 C, 20 C and 27 C. Liquid/slurry takes the "without natural crust cover" series and the optional 40 percent crust reduction is not applied.
2019 sub-zone rows are the unweighted mean over the sub-zones the Refinement itself groups into each of Cool (Cool Temperate Moist, Cool Temperate Dry, Boreal Moist, Boreal Dry), Temperate (Warm Temperate Moist, Warm Temperate Dry) and Warm (Tropical Montane, Tropical Wet, Tropical Moist, Tropical Dry). Liquid/slurry is read at the 6-month retention time, which is the Refinement's own default where retention time is unknown (Table 10.17 footnote 1).
The 2019 pasture value is half of a pair
The Refinement's single 0.47 percent for pasture, range and paddock is
not a drop-in replacement for the 2006 triple. Section 10.4.2 of the
same chapter (p. 10.66) states that it "must be used in conjunction with a
single B0 value of 0.19 m3 CH4 kg-1 of VS excreted", and that this pair
"was judged by the expert panel to be more accurate than emission factors
estimated from regionally based MCFs and animal category based B0";
footnote 2 of Table 10.17 (Updated) (p. 10.70) repeats that pasture MCFs
"must always be used in conjunction with a B0 value of 0.19", and Annex
10B.6 (p. 10.164) derives the pair from grazing measurements on cattle and
sheep, finding no significant difference by climate zone or animal
category. The pair is carried in paired_bo_m3_kg_vs.
Since whep#1137 the Tier 2 kernel honours it by default: the
pasture_bo = "paired" manure-engine option (see manure_engine_options)
prices the pasture stream at 0.19 and every other stream at the
animal-category Bo, and pasture_bo = "species" restores the single
per-species Bo – the hybrid the Refinement rejects – for
reproducibility and sensitivity. method_manure_ch4 records which.
Measured on FAOSTAT 2020 heads, national grain, the Temperate default and
the Global GLEAM 2.0 manure-management split, the pairing moves global
Tier 2 manure CH4 by +0.033 percent (14.3353 to 14.3401 Tg): goats
+1.1 percent (Bo 0.18, pasture a fifth of their weighted MCF), buffalo
+0.84 percent (Bo 0.10, pasture under 1 percent of theirs), cattle
-0.07 percent and sheep unchanged (Bo 0.19 already). Horses, mules and
asses and camels, whose Bo is furthest from 0.19, reach no Tier 2 CH4
in that run. The +30.5 percent buffalo figure first quoted in whep#1137
was measured under the placeholder split that whep#958 replaced, which
sent 60 percent of buffalo manure to pasture.
What the table cannot hold
The 2019 Refinement resolves the anaerobic digester into six
leakage-and-storage classes spanning 1.00 to 13.17 percent, so no single
"Anaerobic Digester" MCF exists to ship. They are carried as six
distinct mms_type values rather than flattened to one number, and no
shipped MMS vocabulary selects one: which class a country's digesters
belong to is an inventory input WHEP does not have (whep#1022). The 2006
digester is NA for the same reason – that edition publishes a 0 to 100
percent range and requires the compiler to evaluate its Formula 1.
Examples
climate_mcf_ipcc
#> # A tibble: 81 × 5
#> edition mms_type climate_zone mcf_percent paired_bo_m3_kg_vs
#> <chr> <chr> <chr> <dbl> <dbl>
#> 1 ipcc_2006 Daily Spread Cool 0.1 NA
#> 2 ipcc_2006 Daily Spread Temperate 0.5 NA
#> 3 ipcc_2006 Daily Spread Warm 1 NA
#> 4 ipcc_2006 Solid Storage Cool 2 NA
#> 5 ipcc_2006 Solid Storage Temperate 4 NA
#> 6 ipcc_2006 Solid Storage Warm 5 NA
#> 7 ipcc_2006 Dry Lot Cool 1 NA
#> 8 ipcc_2006 Dry Lot Temperate 1.5 NA
#> 9 ipcc_2006 Dry Lot Warm 2 NA
#> 10 ipcc_2006 Liquid/Slurry Cool 20 NA
#> # ℹ 71 more rows