Climate Change Projections and Regional Variability in South America

South America exhibits marked heterogeneity in projected climate change impacts owing to its vast latitudinal span, diverse topography and complex hydroclimate systems. Coupled model ensembles, most notably CMIP6, project continent-wide warming that intensifies towards the subtropics and at high altitudes, with temperature increases ranging from 1.5 °C under low-emission pathways to 4 °C or more in the late twenty-first century under high-emission scenarios. Precipitation projections reveal a distinctive dipole: a tendency towards reduced annual rainfall over the northern Amazon and central Andean cordillera, contrasting with wetter conditions in parts of southeastern South America, including the La Plata basin. These shifts are accompanied by a seasonal redistribution of rainfall, with more pronounced extremes and an increased likelihood of heavy-precipitation events. Regional phenomena, such as the South American Monsoon System, the Bolivian High and orographic influences of the Andes, modulate these trends and can enhance drought risk in the Gran Chaco and western Amazon, while exacerbating flood hazards in the southern Atlantic sector. Cryospheric changes in the tropical Andes, including glacier retreat and reduced snow cover, further drive regional aridification and diminish dry-season water availability. The interplay of global forcing, internal variability and downscaling uncertainties underpins much of the spread in projections, emphasising the need for tailored adaptation strategies. Practical applications range from water-resource management in Andean cities to agricultural planning in the Pampas, with governance challenges highlighted by recent extreme events.

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Climate Change Projections and Regional Variability in South America publication trend

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Technical terms

General circulation model (GCM): A mathematical representation of Earth’s atmosphere, ocean and land surface processes used to simulate past and future climate at global scale.

Downscaling: Techniques, either statistical or dynamical, that translate coarse-resolution GCM outputs to finer spatial scales to capture local climate features.

Aridity index (AI): The ratio of mean annual precipitation to potential evapotranspiration, often adjusted for snow presence, used to assess ecosystem water balance.

Shared Socioeconomic Pathways (SSPs): Scenarios describing future societal development and greenhouse-gas emissions, employed to drive climate projections under varying mitigation efforts.

Cryosphere: The portions of Earth’s surface where water is in solid form, including glaciers, snow and permafrost, crucial for regional hydrology.

References

1. Assessment of CMIP6 Performance and Projected Temperature and Precipitation Changes Over South America. Earth Systems and Environment (2021).
2. Extreme rain event highlights the lack of governance to face climate change in the Southeastern coast of Brazil. Geography and Sustainability (2024).
3. Warming-induced cryosphere changes predict drier Andean eco-regions. Environmental Research Letters (2024).
4. Downscaling precipitation and temperature in the Andes: applied methods and performance—a systematic review protocol. Environmental Evidence (2023).