Assessment of EC-Earth3 climate change projections over South America

The downscaling of climate change projections is crucial for impact and adaptation studies, as such studies require higher spatial resolution data than those provided by global CMIP6 models. EC-Earth3 is therefore used as a driving model for dynamic downscaling with the Eta/INPE regional model over SA. In this study, we analyze projected trends under the SSP5-8.5 scenario, focusing on the 2-m air temperature (2 m) and precipitation until the end of the 21st century. Changes are evaluated from 2015 onwards relative to the 1985–2014 climatology and analyzed seasonally (DJF, MAM, JJA, SON). In the near future period, an increasing trend in precipitation is projected over the South Atlantic Convergence Zone (SACZ) during DJF, as well as over northern SA during MAM, while a reduction in precipitation is projected over most of the domain, particularly over the Amazon region. From 2025 onwards, precipitation reductions over the Amazon are projected to predominate in nearly all seasons, while positive changes are projected over parts of northeastern, southeastern, and central SA. This pattern persists in subsequent decades. From 2060 onwards,  precipitation reduction over the SACZ exceeds 300 mm per season in SON and DJF. By the end of the century, a strong negative change is projected across the entire SACZ region. In contrast, a persistent positive change is projected over southern Brazil, likely associated with an increase in extreme precipitation events. This contrast tends to enhance the spatial variability of climate over SA and suggests changes in the South American monsoon system and the continental hydrological cycle. Regarding temperature, initial chances do not exceed ±1 °C over most of central SA. From 2025 onwards, positive changes range from +1 to +3 °C across most of the domain. The warming signal intensifies over time, exceeding +4 °C from 2035 onwards during SON. From the 2040s onward, positive temperature changes dominate across the model domain under the SSP5-8.5 scenario. Projected mean temperature increases exceed +6 °C over the central region from the 2050s onwards. By the end of the century, temperature increase range from +6 to +8 °C over most of Brazil.  The main agricultural production region in Central Brazil exhibits the highest warming rates. The SON season presents the largest temperature increases and precipitation anomalies.