feart-08-00040 February 22, 2020 Time: 17:25 # 1 ORIGINAL RESEARCH published: 25 February 2020 doi: 10.3389/feart.2020.00040 Mass Balance and Climate History of a High-Altitude Glacier, Desert Andes of Chile Christophe Kinnard1*, Patrick Ginot2, Arzhan Surazakov3, Shelley MacDonell3, Lindsey Nicholson4, Nicolas Patris5, Antoine Rabatel2, Andres Rivera6 and Francisco A. Squeo3,7 1 Département des Sciences de l’Environnement, Canada Research Chair in Cryosphere Hydrology, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada, 2 Univ-Grenoble-Alpes, IRD, CNRS, Grenoble-INP, Institut des Géosciences de l’Environnement, Grenoble, France, 3 Centro de Estudios Avanzados en Zonas Áridas, La Serena, Chile, 4 Institute of Atmospheric and Cryospheric Sciences, Innsbruck, Austria, 5 HydroSciences Montpellier (HSM), IRD, CNRS, Université de Montpellier, Montpellier, France, 6 Departamento de Geografía, Universidad de Chile, Santiago, Chile, 7 Instituto de Ecología y Biodiversidad, Universidad de La Serena, La Serena, Chile Glaciers in the dry Chilean Andes provide important ecological services, yet their mass balance response to past and ongoing climate change has been little studied. This study examines the recent (2002–2015), historical (1955–2005), and past (<1900) mass balance history of the high-altitude Guanaco Glacier (29.34◦S, >5000 m), using a combination of glaciological, geodetic, and ice core observations. Mass balance has been predominantly negative since 2002. Analysis of mass balance and meteorological Edited by: data since 2002 suggests that mass balance is currently mostly sensitive to precipitation Bryan G. Mark, variations, while low temperatures, aridity and high solar radiation and wind speeds The Ohio State University, cause large sublimation losses and limited melting. Mass balance reconstructed by United States geodetic methods shows that Guanaco Glacier has been losing mass since at least Reviewed by: Ninglian Wang, 1955, and that mass loss has increased over time until present. An ice core recovered Chinese Academy of Sciences, China from the deepest part of the glacier in 2008 revealed that the glacier is cold-based Pascal Buri, − ◦ University of Alaska Fairbanks, with a 5.5 C basal temperature and a warm reversal of the temperature profile above United States 60-m depth attributed to the recent atmospheric warming trend. Detailed stratigraphic *Correspondence: and stable isotope analyses of the upper 20 m of the core revealed seasonal cycles Christophe Kinnard in the d18O and d2H records with periods varying between 0.5 and 3 m. w.e. a−1. [email protected] Deuterium excess values larger than 10 suggest limited post-depositional sublimation, Specialty section: while the presence of numerous refrozenh ice layers indicate significant summer melt. This article was submitted to Tritium concentration in the upper 20 m of the core was very low, while 210Pb was Cryospheric Sciences, a section of the journal undetected, indicating that the glacier surface in 2008 was at least 100 years old. Taken Frontiers in Earth Science together, these results suggest that Guanaco Glacier formed under drastically different Received: 11 November 2019 climate conditions than today, with humid conditions causing high accumulation rates, Accepted: 04 February 2020 Published: 25 February 2020 reduced sublimation and increased melting. Reconstruction of mass balance based Citation: on correlations with precipitation and streamflow records show periods of sustained Kinnard C, Ginot P, Surazakov A, mass gain in the early 20th century and the 1980s, separated by periods of mass loss. MacDonell S, Nicholson L, Patris N, The southern migration of the South Pacific Subtropical High over the course of the Rabatel A, Rivera A and Squeo FA (2020) Mass Balance and Climate 20th and 21st centuries is proposed as the main mechanism explaining the progressive History of a High-Altitude Glacier, precipitation starvation of glaciers in this area. Desert Andes of Chile. Front. Earth Sci. 8:40. Keywords: glacier mass balance, geodetic mass balance, ice core, dry Andes, climate change, stable isotopes, doi: 10.3389/feart.2020.00040 sublimation, drought Frontiers in Earth Science | www.frontiersin.org 1 February 2020 | Volume 8 | Article 40 feart-08-00040 February 22, 2020 Time: 17:25 # 2 Kinnard et al. Guanaco Glacier Mass Balance History INTRODUCTION over the 6-year monitoring period. Using these data combined with continuous streamflow measurements, Gascoin et al. (2011) Glaciers are important freshwater sources and key regulators of evaluated the mean hydrological contribution of glacier melt in the water cycle (Fountain and Tangborn, 1985; Jansson et al., the upper Huasco River catchments which was found to vary 2003). This is especially true in arid and semi-arid climates between 3 and 24%. where water availability is limited due to low precipitation Glaciological mass balance measurements records can be rates. In addition, the bulk of surface runoff and groundwater extended, or complemented, by calculating geodetic mass recharge is generated in the high mountains, far from the balance from historical satellite and aerial stereoscopic images coastal population centers and cultivated lowland valleys where (Cogley, 2009; Zemp et al., 2013), while longer mass balance the water is needed (e.g., Viviroli et al., 2007). As snow and reconstructions can be derived from ice core records (Ginot ice melt play such an important role in the hydrology of arid et al., 2006). While ice cores have greatly contributed to our zones, these regions are considered very sensitive to future knowledge of past hydroclimatic variability in the tropical Andes temperature changes (Barnett et al., 2005). This situation is (Thompson, 2000; Vimeux et al., 2009), ice core records are striking in the Norte-Chico region (26◦S–32◦S, Figure 1), which almost non-existent in the subtropical region of South America. is the southernmost region of the Desert Andes of Chile (18– In arid zones, ice cores may represent the only source of high 32◦S, Barcaza et al., 2017). The semi-arid climate of Norte- resolution (<decadal) paleoclimate information, as the scarcity of Chico, combined with the marked climate variability arising vegetation and lakes limits the use of tree-ring and lake sediment from coupled atmosphere-ocean oscillations [El Niño Southern proxy records (Neukom and Gergis, 2012; Flantua et al., 2016). Oscillation (ENSO), Madden-Julian Oscillation (MJO)], induces In addition, ice core records from high-altitude glaciers can also a hydric stress on populations (Montecinos and Aceituno, 2003; supply valuable climate information in otherwise data-scarce Garreaud et al., 2009; Juliá et al., 2012). Nonetheless, and owing regions, as high-altitude weather stations are rare in the Desert to efficient irrigation techniques, a productive agriculture sector Andes. To date, only one ‘deep’ (36 m, surface-to-bedrock) ice exists and constitutes the economic pillar of the region. The core paleoclimate record from the South American subtropics has existence and development of several mining projects near the been published, from the Cerro Tapado Glacier in the upper Elqui headwaters of the main transverse valleys in the region also Valley of Norte-Chico (30◦080 S, 69◦550W, 5550 m a.s.l.) (Ginot contribute to the reginal economy but raises environmental et al., 2006). Additionally, preliminary analyses of a 104 m-long and resource equity disputes (Oyarzún and Oyarzún, 2011; ice core form the Cerro Mercedario Glacier (31◦580 S, 70◦070W, Kronenberg, 2013). There is a strong concern that the observed 6100 m a.s.l.) are available (Bolius et al., 2006; Vimeux et al., 2009; (Falvey and Garreaud, 2009) and predicted (Cabré et al., 2016; Ciric et al., 2010). Given the recent persistent drought conditions Bozkurt et al., 2017) warming trend in the high Andes together observed in the region (Garreaud et al., 2017) and the anticipated with the apparent decreasing precipitation over recent decades aridification and warming trend (Boisier et al., 2018), there is a (Fiebig-Wittmaack et al., 2012; Quintana and Aceituno, 2012; need for more information on the response of glaciers to climate Schulz et al., 2012) could result in aggravated water stress in the change both under present and past climate conditions, in order Norte-Chico region. This in turn could exacerbate inter-sector to better assess the sensitivity of glaciers and related meltwater conflicts about water usage and limit future development (Young resources to climate change. The paleoclimate archive contained et al., 2010; Valdés-Pineda et al., 2014). in high-altitude glaciers may also provide the best information Glaciers are sparsely distributed and relatively small in Norte source on past precipitation at high altitudes, which would give Chico. Barcaza et al. (2017) inventoried 1334 glaciers and rock precious insights into natural climate variability and provide glaciers, covering a total area of 126.6 km2. Nicholson et al. a comparative framework for the recent and ongoing drought (2009) inventoried 112 glaciers covering 16.86 km2 and 40 experienced in the region. rock glaciers covering 6.30 km2 in the upper Huasco River This study presents a comprehensive assessment of the mass catchment. Despite their relatively small surface coverage, the balance and climate history of a cold, high-altitude (>5000 m hydrological contribution of an even limited glacier storage can a.s.l.) glacier in the Desert Andes, using a combination of become