The projected disappearance of small glaciers* worldwide threatens to eliminate the water supply for numerous towns in valleys, such as the Ecuadorian capital Quito, fed by the rivers that flow down from the surrounding mountains. But retreating ice is also a threat to freshwater fauna. According to a study published in Nature Climate Change, the local and regional diversity of mountain aquatic fauna will be reduced considerably if predictions are realised. Until now, the impact of global thawing on biodiversity in watercourses had never been calculated in detail.