From Atmosphere to River Catchment: Modeled Global River Runoff Responses to Anthropogenic Aerosol Forcing

Changes in atmospheric aerosol concentrations have the potential to reorganize global precipitation patterns, yet the downstream implications for river systems are not fully understood. This study examines the sensitivity of global river runoff and discharge to anthropogenic aerosol forcing, asking how hydrological regimes differ in an atmosphere with reduced aerosol burdens compared to historical conditions.

We analyze multi-model simulations from the CMIP6 Detection and Attribution Model Intercomparison Project (DAMIP). The analysis focuses on the 1950–1980 era, a period of substantial aerosol emissions, to maximize the potential detection of aerosol-driven hydrological changes. Total runoff outputs from simulations, including and excluding anthropogenic aerosols, are used to force the TRIPpy river-routing model. This offline routing approach allows for a spatially consistent assessment of discharge variability across major global river basins, independent of the coarse resolution of GCM native routing.

We present the study design and preliminary insights into the spatial heterogeneity of aerosol impacts. By isolating the aerosol signature in river discharge, this research contributes to a more integrated understanding of the interplay of aerosol, climate, and hydrology.