Retreating glaciers threaten the food and water supply of 2 billion people around the world, the UN has warned, as current “unprecedented” rates of melting will have unpredictable consequences.

Two-thirds of all irrigated agriculture in the world is likely to be affected in some way by receding glaciers and dwindling snowfall in mountain regions, driven by the climate crisis, according to a Unesco report.

More than 1 billion people live in mountainous regions and, of those in developing countries, up to half are already experiencing food insecurity. That is likely to worsen, as food production in such regions is dependent on mountain waters, melting snow and glaciers, according to the World Water Development Report 2025.