The provision of downscaled global circulation output is the first stage in assessing the
implications of climate change for the water environment. Using only one global climate
model Sweeney and Fealy, 2003 concluded that projected changes in climate will have
potentially large effects on the water environment in Ireland, particularly on flood and
drought frequencies. Increased winter runoff in western parts as a result of wetter winters and
decreased summer runoff, especially in eastern Ireland as a result of substantial reductions in
summer rainfall are projected. Considerable uncertainties however exist from such projections
since they are based on only one GCM. These uncertainties limit the reliability of such
climate scenarios for future water resource management since different GCMs tend to show
different results for areas such as Ireland. This arises from inherent weaknesses they possess
due to problems of scale and feedback. One way of addressing these uncertainties and
providing more reliable inputs to hydrological models is to use multi- model downscaling, and
this approach is presented here
