The study by Immerzeel et al. (2020) highlights the critical role of global water towers—mountain regions that supply water to downstream ecosystems and human populations. These water towers are highly vulnerable to climate change and socio-economic changes, which could negatively impact over 1.9 billion people. The researchers developed a Water Tower Index (WTI) to rank water towers based on their water supply role and downstream dependence. The index considers factors such as water supply, demand, governance, and climate change impacts. The most important water towers, primarily in Asia, are also the most vulnerable. The study emphasizes the need for urgent action to protect these vital water sources. The research also identifies key water towers in different regions, including the Indus, Arctic Ocean Islands, and Cordillera Principal. The study underscores the importance of water towers in global water cycles, biodiversity, and human livelihoods. It warns of the risks posed by climate change, population growth, and poor governance to these critical water resources. The study calls for international policies to conserve and adapt to climate change in mountain regions to ensure water, food, and energy security for millions of people downstream. The research provides a framework for assessing the importance and vulnerability of water towers globally.The study by Immerzeel et al. (2020) highlights the critical role of global water towers—mountain regions that supply water to downstream ecosystems and human populations. These water towers are highly vulnerable to climate change and socio-economic changes, which could negatively impact over 1.9 billion people. The researchers developed a Water Tower Index (WTI) to rank water towers based on their water supply role and downstream dependence. The index considers factors such as water supply, demand, governance, and climate change impacts. The most important water towers, primarily in Asia, are also the most vulnerable. The study emphasizes the need for urgent action to protect these vital water sources. The research also identifies key water towers in different regions, including the Indus, Arctic Ocean Islands, and Cordillera Principal. The study underscores the importance of water towers in global water cycles, biodiversity, and human livelihoods. It warns of the risks posed by climate change, population growth, and poor governance to these critical water resources. The study calls for international policies to conserve and adapt to climate change in mountain regions to ensure water, food, and energy security for millions of people downstream. The research provides a framework for assessing the importance and vulnerability of water towers globally.