Statistical downscaling of temperature, radiation and potential evapotranspiration to produce a multiple GCM ensemble mean for a selection of sites in Ireland

Irish climate is experiencing changes which have been found to be consistent with those occurring at a global scale and there is now growing confidence that these changes are largely attributable to global warming. Between 1890-2004, mean annual temperatures in Ireland rose by 0.7C, based on the data from four, long-term monitoring, synoptic stations. In the absence of strict emissions controls, a doubling of global atmospheric concentrations of CO2 is likely by the end of the 21st century. As a consequence, global temperatures are projected to increase by between 1.8 to 4oC over the same period depending on the climate sensitivity to increased levels of greenhouse gases. In order to determine the likely impact on Irish temperatures and related climatic variables, this paper illustrates a technique for downscaling Global Climate Model output for a selection of sites in Ireland. Results of a weighted ensemble mean, derived from multiple GCMs, are presented in an attempt to address some of the various uncertainties inherent in climate modelling. Projected changes in selected indices of temperature extremes are also presented for the ensemble A2 emissions scenario, as changes in extremes are likely to have a larger and more immediate impact on human society than changes in the mean climate state