Search Climate Insights Directory

The Andean snowpack is the primary water source for households, agriculture, industry, hydropower, and ecosystems in semi-arid central Chile and central-western Argentina. Analysis of regional composite data shows that winter snowpack and river streamflow are closely related and influenced by large-scale Pacific surface temperature changes. High snowpack and streamflow coincide with warm El Niño events, while most extreme dry years occur during cold La Niña events. Additionally, shifts in the Pacific Decadal Oscillation (PDO) in the mid-1940s and 1976-77 correspond to a 27% decrease and 28% increase in mean annual river discharges, respectively, suggesting the PDO causes low-frequency hydrologic variations. While lower PDO values in the late 1990s were not matched by streamflow records—possibly due to melting glaciers—the interplay between ENSO and PDO is highlighted as critical for improving water scarcity forecasts under a changing climate.