Inventories, Uncertainties and Verification

摘要

Are presented scientific inventories in line with official reported data or provide these reason for modification of some elements? Has the uncertainty in emission estimates been reduced by recent improvements in methodology, in particular by verification research? Is a reduction of the uncertainty in emission estimates to be expected in the near or more remote future? What is the meaning of the present quality of emission inventorying for checking commitments under the kyoto protocol? Presented global CH4 inventories showed substantial differences compared with officially reported fossil fuel production/transmissions in Annex I countries. Since the latter are likely to be based on higher tier methods as opposed to the scientifically compiled emissions, the IPCC Tier 1 default factors need to be checked for biases compared with the Tier 2/3 methods and revised where appropriate, in particular coal mines. In the oil and gas industry country-specific management practices are likely to determine the differences; the IPCC methodologies may be checked for revision. Scientific inventories should take the official figures into consideration in revisions of global total source strengths; if those revisions cannot be made within the overall data constraints, it should be clearly flagged that there may be a possible bias in the official national inventories. Presented global CH4 emissions include wastewater/wastewater treatment plants (WWTPs), indicating that for domestic wastewater handling the CP emissions may be much more important than older estimates suggested, in particular in less developed countries. Presented global total estimates for wastewater handling are comparable in size with CH4 emissions from landfills, in particular in countries without sewage treatment. However, the presented figures for industrialised countries are much higher than reported in official national inventories. This could be explained by high uncertainty in input data (amounts of wastewater generated and amounts of BOD loading), other emission factors or by much higher methane recovery than assumed in the global inventories. The presented data suggest that the present IPCC Tier 1 default factors need to be evaluated and that the importance of the methane recovery fraction should be underpinned.