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Carbon dioxide emission reduction scenarios for Finland are compared with respect to the radiative forcing they cause (heating
power due to the absorption of infrared radiation in the atmosphere). Calculations are made with the REFUGE system model using
three carbon cycle models to obtain an uncertainity band for the development of the atmospheric concentration.
The future emissions from the use of fossil fuels in Finland are described with three scenarios. In the reference scenario
(business-as-usual), the emissions and the radiative forcing they cause would grow continuously. In the scenario of moderate
emission reduction, the emissions would decrease annually by 1% from the first half of the next century. The radiative forcing
would hardly decrease during the next century, however. In the scenario of strict emission reductions, the emissions are assumed
to decrease annually by 3%, but the forcing would not decrease until approximately from the middle of the next century depending
on the model used. Still, in the year 2100 the forcing would be considerably higher than the forcing in 1990. Due to the slow
removal of CO2 from the atmosphere by the oceans, it is difficult to reach a decreasing radiative forcing only by limiting fossil CO2 emissions.
The CO2 emissions from fossil fuels in Finland contribute to the global emissions presently by about 0.2%. The relative contribution
of Finnish CO2 emissions from fossil fuels to the global forcing due to CO2 emissions is presently somewhat less than 0.2% due to relatively smaller emissions in the past. The impact of the nonlinearity
of both CO2 removal from the atmosphere and of CO2 absorption of infrared radiation on the results is discussed. 相似文献
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Widespread afforestation has been proposed as one means of addressing the increasing dryland and stream salinity problem in Australia. However, modelling results presented here suggest that large-scale tree planting will substantially reduce river flows and impose costs on downstream water users if planted in areas of high runoff yield. Streamflow reductions in the Macquarie River, NSW, Australia are estimated for a number of tree planting scenarios and global warming forecasts. The modelling framework includes the Sacramento rainfall-runoff model and IQQM, a streamflow routing tool, as well as various global climate model outputs from which daily rainfall and potential evaporation data files have been generated in OzClim, a climate scenario generator. For a 10% increase in tree cover in the headwaters of the Macquarie, we estimate a 17% reduction in inflows to Burrendong Dam. The drying trend for a mid-range scenario of regional rainfall and potential evaporation caused by a global warming of 0.5 degree C may cause an additional 5% reduction in 2030. These flow reductions will decrease the frequency of bird-breeding events in Macquarie Marshes (a RAMSAR protected wetland) and reduce the security of supply to irrigation areas downstream. Inter-decadal climate variability is predicted to have a very significant influence on catchment hydrologic behaviour. A further 20% reduction in flows from the long-term historical mean is possible, should we move into an extended period of below average rainfall years, such as occurred in eastern Australia between 1890 and 1948. Because current consumptive water use is largely adapted to the wetter conditions of post 1949, a return to prolonged dry periods would cause significant environmental stress given the agricultural and domestic water developments that have been instituted. 相似文献