Projecting climate change in South America using variable‐resolution Community Earth System Model: An application to Chile

Abstract

We introduce variable‐resolution enabled Community Earth System Model (VR‐CESM) results simulating historical and future climate conditions at 28 km over South America and 14 km over the Andes. Three 30‐year simulations are performed: a historic (1985–2014), a near future (2030–2059), and an end‐century (2070–2099) simulation under the RCP8.5 scenario. Historic results compare favourably to several temperature and precipitation reanalysis products, though local biases are present, particularly during austral summer. Future simulations highlight broad warming patterns (+3–6°C by end‐century) and heterogeneous precipitation responses across South America that qualitatively agree with prior modelling efforts. Our results reveal that the interaction between temperature and precipitation changes produce shifts in several Köppen–Geiger climates. Notable changes include the near‐elimination of the Andean Tundra or Alpine climates, a 15% decrease in Tropical Rainforests and a Tropical Savannah expansion of 20%. To provide a regionally focused analysis of projected climate change and to illustrate the benefits of variable resolution modelling, we analyse changes in the magnitude and trend in seasonal and daily temperature and precipitation in Chile. We also examined several metrics [e.g., snow water equivalent (SWE), temperatures on wet days, and days below 0°C] to evaluate potential impacts of climate change on the Chilean cryosphere between the end‐of‐century and historic periods, finding wide‐ranging indications of cryospheric decline. These changes are interpreted through reductions in the timing (1–2.5 months earlier peak SWE) and magnitude (200–1,000 mm SWE decreases) of water stored as snow in the Andes, a 10–30% decrease in number of cool season wet days with temperatures below 1°C, and 50–200 fewer days (annually) with minimum temperatures below 0°C. Our aim in producing a high‐resolution dataset of climate projections from VR‐CESM is to support analyses of climate change throughout South America but especially in vulnerable montane regions and to provide additional results for comparison with previous, ongoing, and upcoming modelling efforts.

The Fully Coupled Regionally Refined Model of E3SM Version 2: Overview of the Atmosphere, Land, and River

“…27a,b). This is seen through higher SWE magnitudes and more granular spatial structures in NARRM compared with LR, particularly in coastal mountain ranges such as the Cascades and Sierra Nevada, and corroborates a longhistory of ESM studies that highlight the critical importance of horizontal resolution (≤0.25 • ) in properly representing the mountainous hydrologic cycle (Demory et al, 2014;Rhoades et al, 2017;Kapnick et al, 2018;Palazzi et al, 2019;Bambach et al, 2021;. As shown through the more granular intra-seasonal perspective of the SWE triangle met-rics, certain aspects in the snowpack dynamics are improved with NARRM (e.g., peak water volume), namely in the Pacific Northwest and California (Fig.…”

Relic Groundwater and Prolonged Drought Confound Interpretations of Water Sustainability and Lithium Extraction in Arid Lands

“…The most recent projections of climate change in this region over the next several decades show that average temperatures will continue to increase (by 2–5°C by 2100), though it is important to note that due to the strong influence of the Pacific sea surface temperatures on the regional climate, natural modes of variability have caused hiatuses in this broader warming trend that may also occur in the future (Vuille et al., 2015). The duration of seasonal snow and ice cover will likely decrease (by ∼30 days by 2100) (Bambach et al., 2021), and though there is still uncertainty as to whether regional precipitation is more likely to increase or decrease overall in the future (Minvielle & Garreaud, 2011; Neukom et al., 2015; Segura et al., 2020), the timing of rain events is likely to change, and the intensity increase (Bambach et al., 2021; Pabón‐Caicedo et al., 2020). Recent work shows the potential for increases in overall moisture transport and large precipitation events in this region due to changing dynamics of the South American Monsoon, strengthening easterlies, and available moisture supply from the Amazon Basin (Jordan et al., 2019; Langenbrunner et al., 2019; Pascale et al., 2019; Segura et al., 2020).…”

Decline in Seasonal Snow During a Projected 20-Year Dry Spell

“…Our use of one ESM realization, intentionally selected as an end-member case of likely interest to water management as a 'worst case scenario', is both informative and a limitation. The SSM method can be extended to the other 31 LOCA-downscaled simulations from CMIP5, those in the other ESM ensembles (e.g., HighResMIP [9,87]), Coordinated Regional Climate Downscaling Experiments; [7]), as well as singular ESM studies (e.g., [30,88]).…”