Projected mean and extreme changes in the hydrology of large southern South American river basins under 1.5°C, 2°C and 3°C global warming above the preindustrial level

NATALIA B. MONTROULL; RAMIRO I. SAURRAL; CAMILLONI, INÉS A.

buenos aires

Congreso; Shaping the Future of German-Argentinian Scientific Cooperation ? The Role of Curiosity-Driven Research; 2018

Alexander von Humboldt-Stiftung

In the Conference of the Parties on its 21st session held in Paris countries have agreed to limit ?the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change? (UNFCCC, 2015). In particular, regional studies become relevant to address the impacts on water availability to both provide deeper insight on the justifications to further limit greenhouse gases emission (and related warming) and to design adaptation policies and strategies. The main goal of the research project is to determine which are the impacts on the mean and extreme hydric conditions in response to changes in the mean global temperature of diverse basins in south eastern South America (SESA). The motivation of my research can be summarized in these two questions: ¿How is water availability going to change in SESA in a world 1.5°C, 2°C or 3°C warmer with respect to preindustrial period? ¿Is there a significant difference on impacts between those warming scenarios?We also explore the consequences from following a medium or high-emission Representative Concentration Pathway (RCP) to achieve the different warming targets. In order to determine the possible changes in precipitation, evapotranspiration, runoff and river discharges, we use the VIC distributed hydrology model in combination with bias-corrected Global Climate Model (GCM) outputs from the Inter-Sectorial Impact Model Intercomparison Project phase 2a (ISIMIP). Overall, most of the changes over the basins suggest moister conditions with increasing temperatures, which suggests a positive feedback would exist between temperature and precipitation likely accompanied by higher evapotranspiration, moisture availability and precipitation. The comparison of the RCPs indicates that increases in precipitation, evapotranspiration and runoff would be larger under the medium-emission scenario. When the different responses of the various components of the terrestrial water cycle were integrated, results show that variation of annual mean streamflow in all basins analysed range between ±20%. However, in most cases, the sign of the changes highly depends on the RCP chosen to achieve a warming level. Results show a potential increase of flood events for every target and RCP scenario. With current emission trends close to the 3°C target, this study might be useful to guide decision makers and water management planners.