Assessing the uncertainty associated, with national greenhouse gas emission inventories: a case study for Austria

The uncertainty associated with the Austrian Greenhouse Gas emission invent ory has been determined for the gases CO2, CH4 and N2O and for the overall greenhouse potential. Expert interviews were conducted to obtain uncertaint ies in inventory input data. Based on these interviews, error distributions were developed and combined using Monte-Carlo analysis. Results for all so urces and gases combined indicate in overall uncertainty between 10.5% and 12% depending on the base year considered. Excluding emissions and the unce rtainty associated with forest sinks and natural Sources, overall uncertain ty decreased by 2% points. The mere 'random error', which is considered the level of uncertainty to be achieved with the current methodology (excludin g all systematic errors) is 5% points lower. Detailed evaluation shows that much of the overall uncertainty derives from a lack of understanding the p rocesses associated with N2O emissions from soils. Other important contribu tors to GHG emission uncertainties are CH4 from landfills and forests its C O2 sinks. The uncertainty of the trend has been determined at near 5% point s. with solid waste production (landfills) having the strongest contributio n. Theoretical considerations do not permit a decrease or the trend uncerta inty-even when forest sinks are not considered-below 3% points. (C) 2001 El sevier Science Ltd. All rights reserved.