Mountains are water towers of our world, but their role in global water resources may be altered due to changing climate. This book provides an integrated assessment of the spatial and temporal variability of both recent and future climate change impacts in the Yellow River source region (YRSR) with specific focus on extremes. The book is structured across four different topics from detecting contemporary hydro-climatic changes, comparing three different statistical downscaling methods, assessing elevation dependency of expected changes in temperature, and projecting future climate-induced hydrologic changes in the YRSR. The detection of historical hydro-climatic changes in recent decades indicates that climate change may already be happening and may pose a serious threat to water availability in this region. However, an ensemble of climate change projections for the periods 2046–2065 and 2081–2100 based on two GCMs and three emission scenarios demonstrates that the future water availability of this region would increase due to climate change. This discrepancy suggests that contemporary hydro-climatic experience based on past records alone may not always provide a reliable guide to the future. This study makes an important contribution toward an improved understanding of climate change impacts in the YRSR. The knowledge generated has major implications for water resources management in the Yellow River and will be instructive for climate change impacts studies in other mountain areas.