Mountains cover ~22% of the Earth’s land surface and support ~13% of the global mountain population. The Hindu Kush Himalaya (HKH), one of the world’s largest mountain systems, provides critical ecosystem services-water, food, bioresources, and energy-sustaining about 240 million mountain people. Cold arid environments in the HKH are governed by interactions among precipitation, atmospheric moisture demand, temperature, and elevation. Analysis of ecosystem classes for 2000, 2010, and 2022 reveals marked spatial and temporal shifts across cold arid zones, including the cryosphere, high-altitude wetlands, and alpine vegetation. Change detection (2000-2022) highlights strong spatial heterogeneity in land-cover transitions, indicating diverse, localized responses to climatic change. Overall, the region shows a coupled pattern of vegetation expansion, cryosphere decline, and wetland formation, reflecting climate-driven restructuring of high-elevation ecosystems. These transformations in cold arid ecosystems-across glaciers, snow systems, wetlands, and alpine vegetation-are increasing risks for downstream populations. Declining ecosystem services are likely to reduce agricultural productivity, heighten disaster risks, and undermine human well-being in both mountain and downstream regions. Cold arid ecosystems are therefore critical in the context of climate and global change, requiring targeted attention and sustained investment to enhance resilience and support sustainable development.