validation for total and cumulative land emissions from the Global Carbon Budget, including all bookkeeping models
Details
The historical series pooled under Emissions|CO2|Land|+|Land-use Change are all LUC-scale CO2
SOURCES and are broadly comparable to MAgPIE's +|Land-use Change. Verified against the ingested
validation data (not the parent publications), they form a single positive cloud (Mt CO2/yr, World,
2000-2010): bookkeeping BLUE/OSCAR/GCB/H&C ~2600-6600 and the national-statistics series
FAO_EmisLUC/EDGAR_LU/PRIMAPhist ~2800-5400 - the latter numerically indistinguishable from the
bookkeeping cloud. They differ mainly on PEAT; a second, conceptual axis (INDIRECT/Grassi) matters in
principle but is NOT represented in the ingested data (see Axis 2):
| source | peat | nature (as ingested) |
| BLUE, OSCAR, H&C2023 | incl | net has GCB's peat folded in (see PEAT below) |
| GCB (this fn) | incl | published GCB net (own net column, peat folded in) |
| Gasser et al 2020 | excl | OSCAR bookkeeping (separate fn) |
| FAO_EmisLUC | incl | FAOSTAT net LULUCF ("Land Use total"), a source |
| EDGAR_LU | incl | EDGAR LULUCF CO2, a source |
| PRIMAPhist | incl | PRIMAP-hist CAT5 (LUCF) CO2, a source |
Axis 1 - PEAT. GCB folds a common peat drainage & fires term (~0.7-1.7 Gt CO2/yr) into EVERY bookkeeping
model's net, though only GCB's block breaks it out as a column (verified: each model's net exceeds the sum
of its ex-peat components by exactly that peat). So +|Land-use Change is already consistently
incl-peat across all four models, matching MAgPIE's +|Land-use Change (which also includes peat).
The function reads GCB's peat column and adds, for all four models, a matching ...|+|Peatland child
(closing the net-vs-components gap) and ...|Land-use Change|Excl Peatland (net of peat, matching
MAgPIE's peat-excluded line). Gasser and the national-statistics series are handled elsewhere.
Axis 2 - INDIRECT (Grassi) - NOT represented in the ingested data. In principle the bookkeeping-vs-NGHGI
gap (~5 Gt CO2/yr; Grassi et al. 2021, doi:10.1038/s41558-021-01033-6) arises because country inventories,
reporting the sink-inclusive NET LULUCF over a large managed-land area, embed the environmental sink and
sit far BELOW bookkeeping ELUC - which would make net Emissions|CO2|Land the matching counterpart.
BUT none of the FAO_EmisLUC/EDGAR_LU/PRIMAPhist series ingested here is that Grassi-adjusted NGHGI net:
FAO is FAOSTAT's net "Land Use total" (its forest sink included but modest, so still a ~4 Gt SOURCE),
EDGAR/PRIMAP are LULUCF CO2 series - all positive, LUC-scale, none carrying a net-flux or Indirect sink
series. They must therefore be compared to MAgPIE's +|Land-use Change like the bookkeeping sources,
NOT to net Land. The sink-inclusive NGHGI-net quantity Grassi contrasts with bookkeeping is absent from
this validation cloud, so MAgPIE's own +|Indirect (its Grassi managed-land sink ~-5.6 Gt CO2/yr,
i52_land_carbon_sink) has no inventory counterpart here to validate against.
GCB note - every workbook model's net INCLUDES the common peat drainage & fires (verified: World 2010, GCB 5181 / BLUE 6156 / OSCAR 5775 / H&C 3612, each = its ex-peat components + ~943 peat). GCB's block is the only one that lists peat as a separate column. That peat column is now read and attached as a +|Peatland child to all four, so net = components + peat holds and the Excl Peatland variant matches MAgPIE's line.
Do NOT benchmark net Land against GCB: the only Indirect / net Emissions|CO2|Land series here is
GCB's, where Indirect = the GCB terrestrial sink S_LAND over ALL land (World 2020: -11403 Mt CO2/yr,
~the whole-biosphere sink), NOT the managed-land Grassi quantity MAgPIE reports.