Climate Change Scenarios and Challenges for the Water Environment

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