Estimation of country contributions to the climate change. Viewpoints of radiative forcing and uncertainty of emissions: Dissertation

Global warming that occurs due to emissions from a country or a country group was studied from two different points of view. Firstly, warming effect caused by Finnish emissions from 1900 to 2100 was assessed using a model that describes removal of greenhouse gases from the atmosphere by pulse response functions, and calculates the radiative forcing caused by an increase in atmospheric concentration. Secondly, Finland's share of global emissions was assessed for the time period during which detailed greenhouse gas inventories were available, i.e. from 1990 to 2003, taking into account uncertainties in emission estimates. The uncertainty estimate was made using literature, measurement data and expert judgement on input parameter uncertainties. Stochastic simulation was used to combine the uncertainties. In addition, uncertainties in different emissions trading schemes were compared at EU level. Greenhouse gases covered by the study were those included in the Kyoto Protocol, i.e. carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs) and sulphur hexafluoride (SF6). Sectors covered were energy, industry, transportation, agriculture and waste. LULUCF sectors (land-use, land use change and forestry) were covered more superficially. Finnish greenhouse gas emissions in 2003 were 86 Tg CO2 eq (without LULUCF). According to the results, 95% confidence interval of this figure lies between 82 and 92 Tg CO2 eq. This represents a share of 0.2-0.3% of global emissions. In the same year, Finland's share of global population was 0.1% and share of global GDP 0.4%. The most important contributors to uncertainty were N2O emissions from agricultural soils, N2O from nitric acid production and CH4 from landfills. Inclusion of LULUCF categories in the inventory increased relative uncertainty of net emissions notably (emissions in 2003 were 68 Tg CO2 eq with a 95% confidence interval of 58 to 78 Tg CO2 eq). According to the radiative forcing calculations, forcing caused by Finland will increase from 3 mWm-2 in 1990 to 6-11 mWm-2 by 2100, depending on emission reduction strategies applied, and technological development. In 1990 Finland's share of global radiative forcing was estimated at 0.18% and by 2100 it will decrease to 0.13%, due to increase in global emissions. The results revealed that Finland's share of radiative forcing was smaller than the share of emissions. This was due to Finland's relatively short emission history. It was concluded that uncertainty in EU emissions trading scheme for CO2 (2005-2007) contains rather small uncertainties (±3% based on uncertainties in inventories), but the extension of emissions trading scheme to cover other sectors or gases is likely to increase the uncertainties (up to 21% in Kyoto emissions trading scheme). Both radiative forcing and uncertainty assessment models developed in the thesis can be used in decision making, e.g. for comparing different emission reduction strategies and for planning of future climate commitments.