Changes in Flood Magnitude and Frequency Projected for Vulnerable Regions and Major Wetlands of South America

Abstract The increase in atmospheric CO2 concentration elevates atmospheric temperature and enhances water storage capacity. This could lead to more extreme precipitation events, while simultaneously, higher temperatures may cause land and soil to dry out. Such alterations create ambiguous expectations regarding the direction of hydrological changes in the following decades. This work quantifies streamflow changes on flood discharges in South America based on the MGB‐SA hydrodynamic‐hydrological model forced with the Climate Model Intercomparison Project (CMIP6) ensemble of climate projections. Future projections indicate that floods are expected to increase in magnitude and become up to five times more frequent in Southern Brazil, a region recently impacted by unprecedented flooding. In contrast, ecosystems such as the Amazon and the Pantanal will likely experience less frequent floods in the coming decades. These projections have relevant implications not only for flood risk in populated areas but also for ecological dynamics.