================ 地球水循環システムセミナー ===============
講演タイトル：Impact of Climate Change on River Runoff using Multi-model Ensemble
This study investigates projections of river discharge for twenty-four major rivers during the twenty-first century using fifteen coupled atmosphere-ocean general circulation model (AOGCM) simulations based on Special Report on Emission Scenarios. In order to reduce the model bias and uncertainty, weighted ensemble mean (WEM) is used for multi-model projections. Although it is difficult to reproduce the present river discharge for the individual model, the results of the WEM of the discharges have skillful reproduction for most of rivers. As a result, it is projected that the annual mean precipitation, evaporation, and runoff in the future increase in the high latitudes, Asia monsoon region, and central Africa, and decrease in the Mediterranean region, southern Africa, and central America. The distribution of the precipitation change tends to coincide with the distribution of the river discharge change. At high-latitude rivers (Amur, Lena, Mackenzie, Ob, Yenisei and Yukon), the discharges increase, and the peak timings shift earlier due to the effect of the earlier snow melting by the global warming. At rivers in Middle East (Euphrates), Europe (Danube and Rhine), and the central America (Rio Grande), the discharges tend to decrease. However, we find it difficult to project the river discharges except some basins since the reliable region of the runoff change is smaller than the precipitation change.