Treatment of Uncertainties for National Estimates of Greenhouse Gas Emissions

An assessment has been carried out of uncertainties in the UK's Greenhouse Gas Inventory in 1990 and predicted inventory for 2010. Best available data to represent uncertainties in model input parameters were used in establishing the estimates for individual gases.

The results for the range of gases studied vary. For methane, nitrous oxide and the PFCs, the best estimate emissions fall significantly, and their attendant uncertainties do not change this conclusion. For SF6 and the HFCs, emissions are predicted to rise significantly between 1990 and 2010 (with respect to their uncertainties). This is caused by changes in their uses, together with a shift in the stages in the life cycles of most of the substances of concern (i.e. phasing out of certain substances from common use, recycling of refrigerators, disposal of existing inventories). For carbon dioxide, no overall significant change is anticipated between 1990 and 2010, although increases in emissions from such sources as the burning of natural gas in power stations and the increase in transport is partly countered by decreases in most other sectors.

The data indicate that most probably, a 6% decrease reduction in the total warming potential of the UK emissions of the six considered gases would be anticipated to occur between 1990 and 2010. Owing to the sizes of the samples in the probabilistic simulations (10,000), such a decrease is significant even given that the uncertainties in emissions for these years is just under 20%.