Mountain regions represent about one-quarter of the Earth's terrestrial surface, and are home to approximately 25% of the global population. Mountains are crucial for life. They offer a wealth of ecosystem functions and services including: freshwater, biodiversity, forest products, minerals, habitats for threatened species, landscapes and cultures of exceptional value.

Yet, such wealth is fragile. Threatened by global and climate change, mountain regions face loss of rare and endangered species, modified water balances (including glacial melt), and changing land use altering socio-economic conditions and the livelihoods of people.

UNESCO-MAB assesses the impacts of global and climate change on fragile mountain ecosystems, using mountain biosphere reserves as sites for study and monitoring