Almost 25 percent of the world’s population depend on the mountain cryosphere – glaciers, snow, and permafrost – as their main source of water. But this source is shrinking at an unprecedented pace almost everywhere in the world. Climate change effects on the mountain cryosphere have already altered some rivers’ flows, and impacts on water resources and their uses are expected to further increase in the future. However, the impacts observed vary over regions, seasons and time scales, and uncertainties remain in projections of future impacts.
Water resources management, therefore, has to better deal with uncertainties by taking a risk-based approach and adopting solutions that are robust over a wider array of potential future conditions. Moreover, with the disappearance of glaciers and reaching of so called “peak water”, more abrupt changes in water availability are projected. With more dramatic impacts of higher temperatures, incremental adaptation may be insufficient and transformational adaptation involving more substantive, systemic changes may be needed.
This Trend Sheet summarises the state of research on climate change effects on the mountain cryosphere and its impact on freshwater resources. It provides examples of approaches that can help deal with uncertainties and reviews emerging insights on how to foster transformation.