Mountains provide vital resources to a significant proportion of the global population, particularly as the ‘water towers’ of the world, and as a result of their high biological diversity at genetic, species and ecosystem levels. As well as benefiting people and industries in lowland areas, these ecosystem services (ES) form the basis of most mountain livelihoods. However, despite providing such an unprecedented abundance of ES, mountains remain among the poorest documented ecosystems in this regard. Greater use of the ES framework can help provide a large-scale view of the unique ‘multifunctionality’ of mountains. This paper presents a review of potential climate change and anthropogenic pressures on mountain ES, particularly focusing on water resources scarcity and increasing water demand due to rapid increases of population and utilisation of mountain ES. Adaptation strategies and supporting policy recommendations are also presented. An overview is presented on a global basis, but analysis also focuses on how mountain ES may be differentially affected due to key regional specificities in major mountain systems of the world. Existing policy and international frameworks of relevance to climate adaptation are examined in detail. Based on this, recommendations are presented on future policy directions, to support adaptation measures explicit to mountain ES using an ecosystem-based approach.