Regional climate ensemble simulations for Ireland – impact of climate change on river flooding

• Main Authors: Tido Semmler, Shiyu Wang, Ray Mcgrath, Paul Nolan
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2006
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.596.456; http://www.c4i.ie/docs/RCM_HBV_Ireland_2.pdf

In recent years, uncertainties in climate model projections have become of much interest because such a wide range of future projections have emerged from a combination of emissions scenarios and different general circulation models (GCMs). Decision-makers and scientists have the desire to know whether certain scenarios are more likely than others for different issues, such as river flooding. Through the ensemble approach the uncertainty in regional climate projections as well as in predicted impacts can be determined to estimate which predicted changes and impacts are robust features. To make a first step towards ensemble simulations for Ireland, different regional climate model (RCM) simulations have been performed to predict the climate of Ireland in a high horizontal resolution of 13 km for the time period 2021-2060. Two different GCM formulations as well as four different emissions scenarios have been used to drive the Rossby Centre Regional Atmospheric Model (RCA3) on a model domain including Ireland, the UK and parts of the North Atlantic. The precipitation output of all these different RCA3 simulations has been used as input for the HBV hydrological model, which has been run for the Suir river catchment as a test case. RCA3 and HBV have also been run for 1961-2000 to confirm the ability of the models to simulate present day conditions. Indeed the application of a high resolution RCM in connection with a conceptual hydrological model is shown to be capable of capturing the local variability of river discharge for present-day climate. Results suggest a moderate increase in temperature of 0.5 to 2 degrees Celsius in 2021-2060 compared to 1961-2000. Whereas in winter precipitation and runoff increases are predicted, in summer enhanced surface evaporation coincides with a precipitation decrease, which will have implications on water availability. 1