Almost 90 of the world’s countries have more than one-quarter of their territory in the mountains. More than 50% of the world’s population depends on water sourced from mountains. Mountains also provide high-quality natural products, rich agro-biodiversity, habitats for rare and endangered flora and fauna, and resources for tourism and recreation. However climate and global changes are having serious impacts on mountain ecosystem goods and services, particularly water, biodiversity, and atmospheric circulation. There is therefore an urgent need to raise awareness and promote policy actions to ensure the critical contribution of mountain ecosystems in meeting adaptation and sustainable development goals in upstream and downstream areas alike.