Start with a parsed database whose imported gas accounts match a built-in profile. The default basis is AR6 / GWP100 where the profile provides those factors. Already characterized source totals keep their original basis.

db.calc_ghg(ipcc_report="AR6", time_horizon=100)
ghg = "GHG AR6 GWP-100"
db.units["Satellite account"].loc[ghg]

Result · A new CO2-equivalent satellite account in every existing scenario. Source gas rows remain available. Its magnitude follows their shared mass unit; the method does not convert units.

Retrieve emissions and footprints

Choose the representation of your model:

IOTSector resultsDirect emissions and per-unit supply-chain footprints.SUTActivity and commodity resultsSeparate native emission blocks and commodity footprints.

Choose IOT or SUT to see the relevant environmental matrices.

IOT results

db.calc_all(["f"])
direct_emissions = db.E.loc[ghg]
per_unit_footprint = db.f.loc[ghg]

E contains direct emissions by producing sector. f includes upstream requirements per unit of sector output. Its denominator follows the database’s native monetary or physical unit.

SUT results

db.calc_all(["fc"])
activity_emissions = db.Ea.loc[ghg]
commodity_emissions = db.Ec.loc[ghg]
per_unit_footprint = db.fc.loc[ghg]

Ea and Ec retain activity-side and commodity-side emissions. fc gives the footprint per native commodity unit.

Check the accounting boundary

calc_ghg() characterizes available accounts. Retrieving a missing footprint matrix is the separate calculation shown above. Direct final-demand emissions in EY are characterized too; they must be considered when constructing complete production- or consumption-based totals.

For BONSAI, the built-in AR6/GWP100 profile also includes its specific Accelerated CO2 factor. Other characterization choices require an explicit factor for that flow when present. For sources that supply an already characterized CO2eq total, choosing ipcc_report does not reconstruct the underlying gases. Read GHG characterization and footprints before comparing results across sources or reports.

Check the source profile before characterization

profile = db.database_profile["ghg"]
profile["selected_profile"]
db.get_index("Satellite account")

A selected profile does not certify that all gases exist in the file. For unsupported labels or families, use an explicit factor mapping in GHG characterization and footprints.

Keep a copy or characterize another indicator

calc_ghg() modifies the model and returns None. To keep the original, use characterized = db.calc_ghg(inplace=False) on an uncharacterized model. Do not apply both routes in sequence: adding the same account twice raises an error. Choose a distinct label when adding another indicator.

Troubleshoot a failed calculation

Situation	What to check
No profile can be selected	Inspect the source metadata; supply a supported profile or an explicit gwp mapping.
No gas accounts match	Check that extensions were imported and that their labels match the selected recipe.
Input accounts have different units	Harmonize their magnitudes and units before characterization. The unit argument does not convert values.
The GHG label already exists	Reuse that account, start from the uncharacterized model, or choose a distinct label for another indicator.

See db.calc_ghg() for all arguments, or follow the cross-database comparison.