Projections of Atmospheric Moisture Transport Over South America in a Changing Climate

Climate change has intensified the global water cycle, increased atmospheric moisture, and altered precipitation patterns, leading to extreme rainfall events and droughts. South America is particularly vulnerable to these changes due to its complex climate dynamics and heavy reliance on agriculture and hydropower. This study investigates future projections of atmospheric moisture transport over South America, focusing on Vertically Integrated Moisture Flux (VIMF) and its convergence (VIMFC). Using high-resolution ERA5 reanalysis data and 17 CMIP6 Earth System Models (ESMs), we analyse moisture transport patterns for 2071–2100 under four Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5), compared to a baseline period (1985–2014). The study evaluates 27 hydrological basins, revealing significant regional variations. Under SSP5-8.5, northern Chile and eastern Brazil show increased moisture divergence, while basins like La Plata and Magdalena exhibit stronger convergence. The Peru Pacific Coast basin records the highest annual convergence (4.98 mm day⁻¹), followed by Magdalena (2.25 mm day⁻¹). Conversely, the North Chile Pacific Coast and the East Brazil's South Atlantic Coast showed the largest divergences (−4.54 and −2.99 mm day⁻¹, respectively). The research provides a novel basin-level analysis of atmospheric moisture dynamics, linking changes in moisture transport and convergence directly to potential shifts in precipitation regimes. These results offer critical insights for water resource management, agriculture, and energy planning across South America. High model agreement across scenarios enhances the reliability of these projections, making the study a valuable resource for developing climate adaptation strategies, particularly in possible high-impact regions like northern Argentina, the La Plata Basin, and eastern Brazil.