High mountain ranges and water resources in Peru and California:
High mountain ranges provide important water resources not only for the mountain regions themselves, but also for the surrounding lowland areas. This is especially true for the dry regions in the tropics and subtropics. The article discusses the importance of high mountain ranges at the example of the Andes in Peru and the Sierra Nevada in California. In Peru the water supply is guaranteed up to the desert-like coastal areas by the glaciers in the tropical Andes, especially during the dry season. Climate change is causing glaciers to melt rapidly, jeopardizing the water supply for a growing population and important economic sectors. In California, it is the extensive snow cover of the Sierra Nevada that secures the intensive irrigation of agriculture, hydroelectricity and drinking water supply of the big cities during the dry summer months. Higher temperatures and more precipitation, which falls as rain instead of snow, cause a strong seasonal shift in runoff, which also poses considerable challenges for the water supply in California.