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Uncertainties

Uncertainties in EDGAR3

It has been acknowledged, that providing improved uncertainty estimates is an urgent need for models and policy applications, but also that it is hard to achieve on the short term other than through collective expert judgement. Within the IPCC Inventory Programme a special activity has recently been started aiming at providing default values and a better framework for estimating and reporting of uncertainties. A similar activity has started within GEIA, aiming at the same results at country level as well as on grid level, but for a more extended group of compounds and in a more scientific setting. Comparisons of different datasets, e.g. as done with the EDGAR data, may be an important input to this process.

Therefore, it was decided by the EDGAR team that it was at present not feasible to go beyond the uncertainty tables compiled for Version 2.0 (see Table 1 and 2). However, in addition some apparent conclusions on uncertainty can be drawn from the comparison of V2.0 with other datasets as part of the validation and check for urgent adaptations. For more detailed info on uncertainty in specific inventories we refer to the papers on N2O, NH3 and CO (Bouwman et al. 1995, 1997; Olivier et al, 1999) and conclusions on validation in Olivier et al. (2001b).

To illustrate the usefulness of the uncertainty indications presented here, we translated for methane the qualifications into the percentage ranges mentioned in the notes of these tables. Next, we compared the results with the uncertainty estimates used by IPCC Working Group I for the preparation of the Third Assessment Report (Fig. 1). The overall picture is rather similar, which shows that this simple approach and interpretation of uncertainty ranges is still quite useful for application at global levels.

Table 1. Indication of uncertainty estimate for greenhouse gases. Source: Olivier et al., 1999a.

Main sourceSub-categoryActivity dataEmission FactorTotal Emissions
CO2CH4N2OCO2CH4N2O
Fossil fuel useFossil fuel combustionSSMMSMM
Fossil fuel productionSMM-MM-
BiofuelBiofuel CombustionLSMLLLL
Industry/Solvent useIron & steel productionS-S--S-
Non-ferro productionS-S--S-
Chemicals productionS-SL-SM
Cement productionSS--S--
Solvent useM------
MiscellaneousV------
Landuse/waste treatmentAgricultureS-LL-LL
Animals (excreta; ruminants)S-ML-ML
Biomass burningLSMLLLL
LandfillsL-M--L-
Agricultural waste burningL-LL-LL
Uncontrolled waste burningL------
Natural sourcesNatural soilsM-LL-LL
GrasslandsM-ML-ML
Natural vegetationM-M--M-
Oceans/wetlandsM-LL-LL
LightningS------
CO2CH4N2OCO2CH4N2O
All Sources----SML

Notes:  Expert judgement of uncertainty ranges, which were assigned with the following classification in terms of order of magnitude of the uncertainty in mind: S = small (10%); M = medium (50%); L = large (100%); V = very large (>100%). "-" Indicates that the compound is not applicable for this source or that emissions are negligible.

Table 2. Indication of uncertainty estimate for ozone and aerosol precursors. Source: Olivier et al

Main SourceSub-categoryActivity dataTotal Emissions
CONOxSO2NMVOCNOxSO2NMVOC
Fossil fuel useFossil fuel combustionSMMSMMMSM
Fossil fuel productionS---M---M
BiofuelBiofuel combustionLMMMMLLLL
Industry/solvent useIron % steel productionSMMMLMMML
Non-ferro productionSSMMLLMLL
Chemicals productionSMMLLMMLL
Cement productionS-----M--
Solvent useM---M---M
MiscellaneousV---V---V
Landuse/waste treatmentAgricultureS--------
Animals (excreta; ruminants)S--------
Biomass burningMMLMLLLLL
LandfillsL--------
Agricultural waste burningLLLLLLLLL
Uncontrolled waste burningL---L---V
Natural sourcesNatural soilsMM-L--L--
GrasslandsMM-------
Natural vegetationMM--LM--L
Oceans/wetlandsML---L---
LightningS-L---L--
CONOxSO2NMVOCCONOxSO2NMVOC
All sources-----MMML

Notes:  Expert judgement of uncertainty ranges, which were assigned with the following classification in terms of order of magnitude of the uncertainty in mind: S = small (10%); M = medium (50%); L = large (100%); V = very large (>100%). "-" Indicates that the compound is not applicable for this source or that emissions are negligible.

Figure 1. Comparison of uncertainty estimates for major global methane sources using the uncertainty estimates by the EDGAR team.

Figure 2. Comparison of uncertainty estimates for major global methane sources using the compilation for the Third Assessment Report of IPCC Working Group IFigure 2. Comparison of uncertainty estimates for major global methane sources using the compilation for the Third Assessment Report of IPCC Working Group I

uncertainty2

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DGAR - Emissions Database for Global Atmospheric Research. Link to this website. GEIA - Global Emissions Inventory Activity, of the Netherlands Environmental Assessment Agency. Link to this website. IMAGE: theme-based website logo of the Netherlands Environmental Assessment Agency. Link to this website. FAIR: theme-based website of the Netherlands Environmental Assessment Agency. Link to this website. HYDE: theme-based website logo of the Netherlands Environmental Assessment Agency. Link to this website.