A serious lack of reliable and consistent data severely hampers scientific knowledge about the state of Himalayan glaciers. As a result, the contribution of glacial melt to the Himalayan river basins remains uncertain. This is of grave importance because declining water availability could threaten the food security of more than 70 million people. There is thus an urgent need to improve cross- boundary scientific collaboration and monitoring of glaciers to bridge the knowledge gap and allow policy options to be based on appropriate scientific evidence.