Greenhouse impacts of anthropogenic CH4 and N2O emissions in Finland

The Finnish anthropogenic CH, emissions in 1990 are estimated to be about 250 Gg, with an uncertainty range extending from 160 to 440 Gg. The mast important sources are landfills and animal husbandry. The N2O emissions, which come mainly from agriculture and the nitric acid industry are about 20 Gg in 1990 (uncertainty range 10-30 Gg). The development of the emissions to the year 2010 is reviewed in two scenarios: the base and the reduction scenarios. According to the base scenario, the Finnish CH, emissions will decrease in the near future. Emissions from landfills, energy production, and transportation will decrease because of already decided and partly realized volume and technical changes in these sectors. The average reduction potential of 50%, as assumed in the reduction scenario, is considered achievable. N2O emissions, on the other hand, are expected to increase as emissions from energy production and transportation will grow due to an increasing use of fluidized bed boilers and catalytic converters in cars. The average reduction potential of 50%, as assumed in the reduction scenario, is optimistic. Anthropogenic CH4 and N2O emissions presently cause about 30% of the direct radiative forcing due to Finnish anthropogenic greenhouse gas emissions. This share would be even larger if the indirect impacts of CH4 were included. The contribution of CH4 can be controlled due to its relatively short atmospheric lifetime and due to the existing emission reduction potential. Nitrous oxide has a long atmospheric lifetime and its emission control possiblities are limited; consequently, the greenhouse impact of N2O seems to be increasing even if the emissions were limited somehow.