Mountains provide more than 40% of global goods and services. The ecosystem services arising from the Hindu Kush-Himalayas (HKH) in the form of water, biodiversity and niche products, hydroelectricity, timber, mineral resources, and recreation are enormous. The HKH region is enriched by a diversity of cultures, ethnic groups, and traditional knowledge systems. Thus, it is a paradox that, in spite of rich natural resources and cultures, poverty is rampant. Additionally, the HKH is a hotspot for climate change impacts, but the region has been identified as a data deficient during the 2007 assessment report of the Intergovernmental Panel on Climate Change (IPCC). Since then, some progress has been made to fill the data gap, specifically relating to biodiversity, cryosphere, and climate change. This chapter introduces the HKH region and elaborates the need for modeling in the context of dealing with climate change.