Water Resources Change in Central-Western Argentina Under the Paris Agreement Warming Targets

Abstract

This study documents the projected changes in several components (precipitation, runoff, snow cover and depth, soil moisture) of the hydrological cycle in Central-Western Argentina (CWA) based on the simulations from the IPSL-CM6A-LR model for the warming levels proposed in the Paris Agreement. These warming levels represent the future increase in mean annual temperature of 1.5 and 2°C compared to pre-industrial conditions. A novel regional approach, that uses a set of low-emissions shared socioeconomic pathways (SSP) compatible with the Paris Agreement goals, has been applied here for the evaluation of the potential impacts of temperature increase in both the mountainous areas of the Andes and the lowlands on the eastern portion of CWA. Our results show that the timing of reaching the 1.5°C warming level would be between 2032 and 2036 in the CWA lowlands east of the Andes, while this warming level in the Andes mountains of CWA would be 10–15 years earlier as result of the stronger warming with elevation. The higher 2°C warming level would be reached before 2050 in the Andes mountains. Even using the more aggressive mitigation pathways available in the scientific literature (SSP1-1.9 and SSP1-2.6), the IPSL-CM6A-LR model ensemble shows a robust drying signal in the wintertime precipitation over the Andes mountains, which is a concerning result because it implies a reduction of the already scarce water resources draining to the adjacent semi-arid foothills. Our results also show that this drying should be linked to the poleward expansion of the Hadley Circulation. In the lowlands farther east from the Andes, the summertime monsoonal precipitation provides the water resources that are projected to increase under the selected emissions pathways. The expected changes in the analyzed components of the hydrological cycle would be strengthened under the 2°C warming level, particularly the decline of snow amount and surface runoff in the Andes. The results of this study provide insights into the expected impacts of the 1.5 and 2°C warming levels in the CWA regional water resources, which may set the stage for the new discussions of possible options to mitigate them at country and regional levels.

Projected impacts of 1.5 and 2°C global warming on temperature and precipitation patterns in South America

“…To this end, some studies have sought to analyse the regional impacts of 1.5 and 2°C global warming on a global scale (e.g., Aerenson et al ., 2018; IPCC, 2018) and in detail for some regions, such as for Australia (King et al ., 2017), United States (Karmalkar and Bradley, 2017), Eurasia (Chen et al ., 2019, 2020a), China (Chen et al ., 2017; Fu et al ., 2018; Sui et al ., 2018; Chen and Sun, 2019; Chen et al ., 2020b) and in Central‐Western Argentina (Rivera et al ., 2020). However, studies evaluating such impacts in detail across South America are still scarce.…”

Variability and Changes in Temperature, Precipitation and Snow in the Desaguadero-Salado-Chadileuvú-Curacó Basin, Argentina

“…In arid to semiarid regions of the world, water availability is facing more recurrent reductions [10,11]. In particular, central-western Argentina has undergone a sustained increase in the annual mean temperature, an increase in annual precipitation and in the frequency of extreme precipitation events towards the eastern lowlands of the region, and a sustained precipitation decline over the Andes [11][12][13]. This declining precipitation favors decreases in snow accumulation and, consequently, streamflow droughts [14,15].…”

“…Future projections indicate that the Andes region is expected to experience more marked temperature increases [16,17]. Furthermore, the observed decline in precipitation since the last century is projected to persist, leading to an increased frequency of drought conditions [13,18,19]. The combination of reduced precipitation and increasing temperatures will contribute to glacier mass balance losses and trigger premature snowpack melting, which poses significant challenges for water management [17,20].…”

“…This expansion was attributed mainly to increased greenhouse gas emissions, ozone depletion effects, and internal climate variability [23,24]. One of the main climatic forces that modulates interannual hydroclimate variability is the El Niño-Southern Oscillation (ENSO) [13,25,26]. Precipitation and streamflow present positive anomalies during El Niño years, while La Niña years favor reduced snowfall and potential streamflow drought conditions [26,27].…”

“…In particular, the Desaguadero-Salado-Chadileuvú-Curacó basin, located in centralwestern Argentina, presents high vulnerability to climate variability and climate change due to (1) the complex system of water resources on which all socioeconomic activities in the region depend, (2) the changes in the hydrological cycle that have occurred in recent decades [13,16], and (3) the large population that the basin encompasses (approximately 3.5 million inhabitants) [28]. According to [28], the main critical situations that occur in the basin are associated with floods and droughts of various origins, as well as processes of salinization, erosion, and environmental contamination favored by anthropic processes.…”