About 25% of the world’s population depends on the meltwater from mountain glaciers. However, the glaciers are currently on a retreat, which potentially has large effects on the water cycle and food security. To learn more about the dynamics and responses of the glaciers under changes in climate conditions, Dr Walter Immerzeel and his team use the relatively novel technique of unmanned aerial vehicles to study the spatial and temporal dynamics of the Lirung Glacier in an unprecedented detail. For this, they venture high in the Nepalese Himalayas twice a year on 4-day walks to an elevation of 4200 m.