Mountains act as water towers, capturing water from the atmosphere to later be released downstream. However, mountains are sensitive to climate change and their climatology is difficult to predict due to complex topography and elevational effects. The water security of 90 million people depends upon the water towers of the Andes, where the cryospheric components of the water cycle (snow and glacier ice) are rapidly changing. In “Deplete and Retreat: the Future of Andean Water Towers,” we aim to upskill our capability to project future change, by combining state-of-the-art regional climate, mass-balance, ice flow and hydrology models. Here, we present initial findings from our project. This includes progress in monitoring and modelling the climate of the Andes, observing and simulating glacier change, and understanding of how the changes occurring in our warming world are impacting Andean water resources.