Abstract

The annual reporting procedures of the United Nations Framework Convention on Climate Change (UNFCCC) have now produced greenhouse gas (GHG) emission inventories from 40 so-called Annex I countries for 18 years. This article analyses a subset of these data: emissions from road transport. The article compares the reported data with the technical guidance on GHG emission inventories provided by the Intergovernmental Panel on Climate Change (IPCC). The analysis suggests that some countries use the IPCC's default emission factors, whereas other countries use country-specific values. In the case of diesel-fuelled road transport, the estimated emissions appear to be generally comparable between all countries for all years. For CO2 emissions from gasoline-fuelled road transport, the picture is less clear. The results suggest that the default emission factor for CO2 from motor gasoline as provided by the IPCC is about 3-5% too low. Countries that seem to apply this default value might therefore underestimate their emissions by the same percentage. The effect of this possible underestimate on trends is, however, very small. Despite the possible problem with the default emission factor, the quantification of the trend in emissions is only slightly influenced by this. © 2011 Earthscan.

Abstract

Mercury is a global pollutant that poses threats to ecosystems and to human health. Due to its global transport, mercury contamination is found in regions of the Earth that are remote from major emissions areas, including the Polar regions. Global anthropogenic emission inventories identify important sectors and industries responsible for emissions at a national level; however, to be useful for air transport modelling, more precise information on the locations of emission is required. This paper describes the methodology applied, and the results of work that was conducted to geospatially distribute anthropogenic mercury emissions as part of the global anthropogenic mercury emissions inventory for 2015 prepared by AMAP/UNEP for the Global Mercury Assessment (GMA) 2018 (UN Environment, 2019). This work includes the identification and use of emission point sources as well as distributing diffuse emissions for 21 emission (industry) sectors. The basic approach involves assigning emission estimates to geo-located point sources, using reported emissions information where available, and otherwise assigning a modelled emission to the point. Emissions which cannot be assigned to point sources are distributed using sector-specific proxies. Mercury speciation highly depends on industry processes and air pollution control technology. Different Hg speciation ratios are therefore applied per sector and country technology level. The resulting global emission datasets include total mercury (HgT), gaseous elemental mercury (Hg0), divalent mercury (Hg2+) and particulate mercury (HgP) in kg per year per raster cell (kg/a). The spatial resolution is flexible and the vertical resolution of the data is based on a set of predefined height classes. The resolution of the GMA2018 emission data is 0.25° × 0.25° with three (physical emission) height classes (0–50, 50–150 and " 150m). A comparison with the EMEP European mercury emission was made based on spatial correlation between the two datasets. Suggested improvements for future work include the further development of proxy data and the implementation of a more structured reporting of emissions by countries.