ALT Changes in basin-scale sediment source-to-sink processes in response to climate change and human activities. The overall terrestrial sediment flux can be increased by sediment mobilization from retreated glaciers and thermokarst landscapes but decreased by the formation of natural and anthropogenic sediment sinks, with the net effect varying spatially. a, Present-day sediment source-to-sink processes. b, Sediment source-to-sink processes in a warmer future with intensified human activities. Vegetation change (for example, reforestation, deforestation and vegetation succession in proglacial areas) add uncertainties in estimating future changes in sediment yield.

ALT Sediment-transport regimes shift under a warming climate, in three stages: stage I, thermally controlled; stage II, thermally and precipitation-controlled; and stage III, precipitation-controlled, where pluvial processes, such as extreme rainfall and flooding, dominate. The timing of peak meltwater is inferred from a global-scale assessment of glacierized basins11, wherein the timing of completion of deglaciation is inferred from regional projections of cryosphere degradation189,190,191. The concept of peak sediment refers to refs.75,176 and further incorporates the constraints of thermally controlled and ice-free erodible landscapes, meltwater flux and various rainfall scenarios in the upper panel. The three brown curves represent sediment fluxes and the timing of peak sediment under different erosive rainfall scenarios: A (decreasing), B (stable) and C (increasing). The timing and potential time range of the peak sediment flux are marked by the solid circle and arrows, respectively.