Assessment of Projected Change in Temperature, Precipitation, and Related Variables over South America Using CMIP5

Anthropogenic climate change is broadly projected by climate models to bring widespread changes in temperature and precipitation over South America. These impacts on temperature are characterized by a general warming with magnitudes depending on location, while those in precipitation exhibit considerable regional variability both in magnitude and sign. Furthermore, there is a notable variability among the projections by different models, which introduces considerable uncertainty in their results. Since climate change will be associated with societal and environmental impacts, it is important to constrain this model uncertainty to gain a better understanding of how temperature and precipitation will change across the continent. Towards this goal, we investigate projected changes in several key climate variables, related to temperature and precipitation, in future climate simulations using data from the CMIP5 suite of global climate models. The climate variables analyzed include zonal and meridional winds, evapotranspiration, integrated vapor transport, vertical motion, and sea level pressure. Results show a wide spread of inter-model variability in the different variables across the suite, with considerable regional variability in the magnitude and direction of changes within each model. Regional differences in projected change of temperature and precipitation can often be readily attributed to thermodynamic and dynamic changes, therefore understanding why some models show different patterns and magnitudes of change than others helps to further explain the physical mechanisms behind future change and model projection uncertainty.