The case of a southern European glacier disappearing under recent warming that survived Roman and Medieval warm periods

1 The case of a southern European glacier disappearing 1 under recent warming that survived Roman and Medieval 2 warm periods 3 Ana Moreno1, Miguel Bartolomé2, Juan Ignacio López-Moreno1, Jorge Pey1,3, Pablo 4 Corella4, Jordi García-Orellana5,6, Carlos SanchoŦ, María Leunda7, Graciela Gil5 Romera8,1, Penélope González-Sampériz1, Carlos Pérez-Mejías9, Francisco Navarro10, 6 Jaime Otero-García10, Javier Lapazaran10, Esteban Alonso-González1, Cristina Cid11, 7 Jerónimo López-Martínez12, Belén Oliva-Urcia12, Sérgio Henrique Faria13,14, María José 8 Sierra15, Rocío Millán15, Xavier Querol16, Andrés Alastuey16 and José M. García-Ruíz1 9 1. Departamento de Procesos Geoambientales y Cambio Global, Instituto Pirenaico de Ecología – CSIC, 10 50059, Zaragoza, Spain 11 2. Departamento de Geología, Museo de Ciencias Naturales - CSIC, Madrid, 28034, Spain 12 3. Fundación Aragonesa para la Investigación y el Desarrollo, ARAID, Zaragoza, Spain 13 4. Université Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, 38000 Grenoble, France 14 5. Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Barcelona, Spain 15 6. Departament de Física, Universitat Autònoma de Barcelona, Barcelona, Spain 16 7. Institute of Plant Sciences & Oeschger Centre for Climate Change Research. Altenbergrain 21, 3013 17 Bern, Switzerland 18 8. Department of Ecology, Faculty of Biology, Philipps-Marburg University, Marburg, Germany 19 9. Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, 710049, China 20 10. Departamento de Matemática Aplicada a las TIC, ETSI de Telecomunicación, Universidad Politécnica 21 de Madrid, Madrid, Spain 22 11. Centro de Astrobiología – CSIC-INTA, Madrid, Spain 23 12. Departamento de Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, 24 Madrid, Spain 25 13. Basque Centre for Climate Change (BC3), 48940, Leioa, Spain 26 14. IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain 27 15. CIEMAT — Environmental Department (DMA), Avenida Complutense 40, E-28040 Madrid, Spain 28 16. Institute of Environmental Assessment and Water Research – CSIC, 08034 Barcelona, Spain 29 30 Ŧ Deceased 31 Corresponding author: Ana Moreno ([email protected]) ORCID: 0000-0001-735732 584X 33 Keywords 34 Pyrenees, mountain glacier, current global warming, Medieval Climate Anomaly 35 36 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 2 Abstract 37 Mountain glaciers have generally experienced an accelerated retreat over the last 38 three decades as a rapid response to current global warming. However, the response 39 to previous warm periods in the Holocene is not well-described for glaciers of the of 40 southern Europe mountain ranges, such as the Pyrenees. The situation during the 41 Medieval Climate Anomaly (900-1300 CE) is particularly relevant since it is not certain 42 whether the glaciers just experienced significant ice loss or whether they actually 43 disappeared. We present here the first chronological study of a glacier located in the 44 Central Pyrenees (N Spain), the Monte Perdido Glacier (MPG), carried out by different 45 radiochronological techniques and their comparison with geochemical proxies with 46 neighboring paleoclimate records. The result of the chronological model proves that 47 the glacier endured during the Roman Period and the Medieval Climate Anomaly. The 48 lack of ice from last 600 years indicates that the ice formed during the Little Ice Age 49 has melted away. The analyses of the content of several metals of anthropogenic 50 origin, such as Zn, Se, Cd, Hg, Pb, appear in low amounts in MPG ice, which further 51 supports our age model in which the record from the industrial period is lost. This 52 study confirms the exceptional warming of the last decades in the context of last two 53 millennia. We demonstrate that we are facing an unprecedented retreat of the 54 Pyrenean glaciers which survival is compromised beyond a few decades. 55 56 57 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 3 1. Introduction 58 Mountain glaciers are often sensitive to climate variations on temporal scales from 59 decades to centuries. It is well known that summer temperature and winter 60 precipitation are the most important climate parameters influencing glacier mass 61 balance (Oerlemans, 2001). Therefore, continuous records of past glacier size 62 fluctuations provide valuable information about the timing and magnitude of Holocene 63 climate shifts (Solomina et al., 2015, 2016), which contributed to explain the 64 characteristics and evolution of plant cover, human movements and land use. Several 65 glacier advances during the Neoglacial (which started around 6000-5000 yr ago) have 66 been identified and associated to sustained cooling periods across the North Atlantic 67 (Wanner et al., 2011). The most recent period of global glacier expansion took place 68 during the Little Ice Age (LIA), beginning in the 13th century and reaching a maximum 69 between the 17th and 19th centuries (Solomina et al., 2016). Afterwards, most glaciers 70 worldwide have retreated rapidly, as indicated by measurements of ice volume and 71 ice-covered area, and this trend seems to have accelerated over the last three decades 72 (Marzeion et al., 2014; Zemp et al., 2015, 2019). 73 Despite broad agreement on millennial-scale trends in global glacier fluctuations and 74 Holocene climate variability (Davis et al., 2009; Solomina et al., 2015), regional 75 variations are not so well constrained. For instance, for the Pyrenees, a mountain 76 range that currently hosts the majority of the southernmost glaciers in Europe, there is 77 a significant lack of knowledge about Holocene glacier fluctuations, as indicated scarce 78 evidences of glacier advances during the Neoglacial period (García-Ruiz et al., 2014; 79 Gellatly et al., 1992). Based on Pyrenean tree-ring chronologies, summer temperatures 80 during the Medieval Climate Anomaly (MCA, circa 900–1300 CE) were estimated to be 81 as warm as those of the 20th century (Büntgen et al., 2017), but no information has 82 been obtained on the glacier response to MCA warming. Conversely, glacier advance 83 during the LIA is well constrained in the Mediterranean mountains (García-Ruiz et al., 84 2014; González Trueba et al., 2008; Hughes, 2018; Oliva et al., 2018) and a significant 85 deglaciation is also evident in recent times (López-Moreno et al., 2016; Rico et al., 86 2017). Thus, Pyrenean glaciers have exhibited during the 20th and 21st centuries multi87 decadal variations similar to those of other mountain ranges in the world. In particular, 88 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 4 the period from the 1980s to present has been the most intense in terms of number of 89 glaciers that disappeared (from 39 inventoried Pyrenean glaciers in 1984 to 19 at 90 present) (Rico et al., 2017). Given the small size of the Pyrenean glaciers and their 91 current critical situation in the context of global warming, we hypothesize that they 92 could have disappeared completely during the aforementioned warm periods 93 This study is focused on Monte Perdido Glacier, located in the Spanish Central 94 Pyrenees, which is currently one of the best monitored small glaciers (<0.5 km2) 95 worldwide. Recent research based on different ground-based remote sensing 96 techniques has demonstrated a rapid retreat of this glacier, with an average loss of ice 97 thickness of about one meter per year since 1981 (López-Moreno et al., 2019). These 98 results, together with the evidences of long-term retreat since the LIA glacier position 99 indicated by pictures and moraines, suggest that this glacier could disappear over the 100 next few decades (López-Moreno et al., 2016). The present study relies on a variety of 101 dating techniques and on the analysis of several proxies associated to environmental 102 and anthropogenic changes to construct, for the first time, the chronology of an ice 103 sequence from a Pyrenean glacier. Such analyses will respond the key question of 104 whether Pyrenean glaciers may have survived previous Holocene warm periods. 105 2. Study area 106 The Monte Perdido Glacier (MPG, 42°40′50′′N; 0°02′15′′E.) is located in the Central 107 Spanish Pyrenees, in the Ordesa and Monte Perdido National Park (OMPNP) (Fig.1). It 108 currently consists of two separate ice bodies, which were connected in the past. Both 109 are north facing and lie on structural flats beneath the main summit of the Monte 110 Perdido Peak (3355 m a.s.l.) and are surrounded by vertical cliffs of 500–800 m in 111 height. At the base of the cliffs, the Cinca River flows directly from the glacier and the 112 surrounding slopes, and has created a longitudinal west–east basin called the Marboré 113 Cirque (5.8 km2). This is the area within the Pyrenees with the highest variety of recent 114 morainic deposits (García-Ruiz et al., 2014). Additionally, a a 6-m thick sediment core 115 obtained in 2011 from a lake inside the cirque (Marboré Lake) contains valuale 116 information from the last 14,600 years of the depositional evolution of the lake (Oliva117 Urcia et al., 2018) and of the regional variations in the vegetation cover (Leunda et al., 118 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 5 2017). The Marboré Lake (2595 m a.s.l.) is located in the Marboré or Tucarroya Cirque, 119 in the northern face of the Monte Perdido massif. The distance between the lake and 120 the MPG is approximately 1300 m and, therefore, both have been affected by similar 121 palaeoenvironmental conditions. 122 Recent measurements indicate that the total surface area of MP glacier in 2016 was 123 0.385 km2 (López-Moreno et al., 2016). During the period 2011–2019, the glacier ice 124 thickness decreased by 7.4 m on average, though such losses exhibit a marked spatial 125 and temporal variability (Fig. S1, Supplementary Material). According to recent 126 measurements of air temperature (July 2014 to October 2017), the 0 °C isotherm lies 127 at 2945 m a.s.l., suggesting that the potential glacier accumulation area is very small, 128 even inexistent during warm years. In an average summer (June to September; 129 temperature measurements were conducted from 2014 to 2017), the temperature at 130 the foot of the glacier is 7.3 °C. No direct observations of precipitation are available at 131 the glacier location, but the maximum accumulation of snow in late April during the 132 three available years was 3.23 m, and average snow density was 454 kg m-3 measured 133 in the field, indicating that total water equivalent during the main accumulation period 134 (October to April) could be close to 1500 mm (López-Moreno et al., 2019). 135 3. Material and methods 136 3.1. Ice sampling and storage 137 Ice drilling in MPG was carried out in September 2017 using a Kovacs ice coring device 138 at three sites. These sites were selected based on previously obtained ground139 penetrating radar (GPR) results, which, combined with glacier dynamics modelling, 140 suggested that the oldest ice could be located at these locations since the thickness 141 was over 30 m and there was no movement of the ice (López-Moreno et al., 2019) (Fig. 142 1). Unfortunately, none of the glacio-meteorological and topographical criteria 143 required to obtain a preserved ice-core stratigraphy, such as low temperatures to 144 prevent water percolation, or a large extension and flat surface topography to 145 minimize the influence of glacier flow (Garzonio et al., 2018), are currently met in the 146 glacier. With this technique, only three short ice cores of 4, 3 and 2 m in length could 147 be recovered, which could not provide a complete chrono-stratigraphical ice sequence. 148 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 6 The cores were preserved intact and later stored at 60 °C at the BC3-IzotzaLab ice 149 core facility (Leioa, Spain) but not used in this study. 150 Based on the poor core recovery, we changed our drilling strategy and, to collect ice 151 samples in an ordered chrono-stratigraphical sequence covering from the oldest to the 152 newest ice preserved in the glacier, we took samples in an area with no evidence of 153 current ice movement, as confirmed by results from interferometric radar and GNSS 154 measurements (López-Moreno et al., 2019) (Fig.S2). This sector has been eroded to 155 form a current steady slope of 20° where it is possible to establish a relation between 156 the sample distances and the ice depth in a formerly much less steep glacier surface. 157 Due to the small size of this glacier, the ice needs to be frozen to bedrock, and hence 158 nearly stagnant, to become of substantial age, i.e., a few hundred years or more, as 159 indicated by previous studies in similar glaciers Gabrielli et al., 2016; Haeberli et al., 160 2004). Therefore, we measured one-meter thickness using the Jacob's staff at every 161 sampling point to measure stratigraphic thicknesses since bedding was unclear (Fig. 162 S2). Once cleaned the most superficial ice to avoid new ice formed recently, we 163 recovered at every sampling position 3–4 small cores (6 cm in diameter and 25 cm in 164 length) using a custom stainless steel crown adaptor on a cordless power drill (see Fig. 165 S2 in Supplementary Material). Following that sampling procedure we recovered a 166 total of 100 samples, every one constituted by 3-4 cylinders, which represent the 167 whole ice sequence in MP glacier. Those ice samples were stored in a freezer room in 168 Zaragoza and further analysed to obtain their chronology (combining 210Pb, 137Cs and 169 14C techniques) and their geochemical composition (trace element and Hg 170 concentrations) (see below). 171 3.2. Dating by 210Pb and 137Cs. 172 The isotope 137Cs usually associated to the fallout from nuclear tests during the 1950s 173 and the 1960s, as well as the Chernobyl (1986) and Fukushima (2011) accidents was 174 investigated by -spectrometry in the uppermost five samples in MPG, but no trace 175 could be detected (Table S1 in Supplementary Material). This implies that all samples 176 are older than 60–65 years and therefore they were not exposed to the atmosphere 177 after 1950 CE. Another possibility that was discarded once we had 14C dates, is that all 178 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 7 samples were younger than 1950 CE. Additionally, up to ten samples were selected 179 from the 100 samples that constitute the whole ice sequence to carry out 210Pb 180 analysis as an independent dating method to obtain chronologies for about the last 181 hundred years of glacier ice (Eichler et al., 2000; Herren et al., 2013). Those samples 182 were selected from the top of the sequence (Table S2). Determination of 210Pb 183 activities was accomplished through the measurement of its daughter nuclide, 210Po, 184 by -spectrometry following the methodology described in (Sanchez-Cabeza et al., 185 1998) (Table S2 in Supplementary Material). Similarly, 210Pb activity was also 186 undetectable in most cases, except in three samples (MP100, MP73 and MP76) with 187 concentrations above minimum detection activity (MDA; Table S2). Probably, the 188 MP100 sample contained the 210Pb recently deposited because it was the most 189 superficial sample, therefore in contact with the atmosphere. However, this sample, as 190 well as samples MP73 and MP76 contained a large amount of lithogenic particulate 191 material from atmospheric dust or ash deposits. The absence of 210Pb activity in the 192 analysed samples does not allow constructing an age-depth model for the last 100 193 years indicating that MPG ice samples were very likely older and the 210Pb had 194 completely decayed. We then built up the proposed MPG chronology using AMS 14C 195 dating. 196 3.3.Dating by 14C method. 197 Sixteen accelerator mass spectrometry (AMS) 14C dates from MPG ice were obtained 198 by combining bulk organic matter (9 samples), pollen concentrates (3 samples), bulk 199 sediment accumulated in filters (2 filters), and water-insoluble organic carbon (WIOC) 200 particles (2 samples) (Table 1). First, using a binocular microscope [x10], we selected 201 organic particles for dating from the nine selected bulk samples, once the ice sample 202 was melted. However, the small size prevented us from classifying the organic 203 remains. All the amorphous particles were sent to the dating laboratory (Direct AMS, 204 Seattle, USA). Pollen concentrates were prepared from three selected samples (30, 70 205 and 100 m depth) to complete the previous set of samples following the standard 206 palynological method, including a chemical treatment and mineral separation in heavy 207 liquid (Thoulet: density 2.0; Moore et al., 1991). Additionally, two ice samples 208 previously melted (67 and 81 m depth) were filtered throughout a filtration line 209 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 8 connected to a vacuum pump using 47 mm quartz fiber filters (PALL tissuquarzt 210 2500QAT-UP), parameterized at controlled conditions (temperature: 22–24 °C; relative 211 humidity 25–35%) and weighted twice in different days. Abundant material was 212 obtained, but no control was made on the composition and amount of organic 213 material versus other type of inputs. Concentrated pollen samples and filters were 214 dated at the same laboratory (Direct AMS, Seattle, USA). Since organic fragments 215 (plants, wood, insects) are rarely found in mountain glaciers, a new, complementary 216 dating tool was recently developed based on extracting the microgram-amounts of the 217 water-insoluble organic carbon (WIOC) fraction of carbonaceous aerosols embedded in 218 the ice matrix for subsequent 14C dating (Uglietti et al., 2016). Two samples were dated 219 by the WIOC technique at the Laboratory of Environmental Chemistry, Paul Scherrer 220 Institute, Switzerland, following the usual procedures including removing the outer 221 part of the ice core segment for decontamination purposes (Jenk et al., 2009). 222 Finally, from the initial 16 dates, we had to discard seven (see the criteria in section 4.1 223 below) and the age model was developed including nine samples (eight from bulk 224 organic matter and one from the WIOC technique; Table 1). Those nine dates were 225 converted into calendar ages by the CALIB 5.0.2 software, which uses the most 226 updated dataset, INTCAL13 (Reimer et al., 2013) (Table 1). The median of the one- 227 probability interval was selected for these dates, resulting in large errors (230 years on 228 average) in the obtained calendar ages. The depth–age model was created using the R 229 package CLAM 2.2 (Blaauw, 2010; Blaauw et al., 2019) (Fig. 2). Given the scattered 230 depths at which dates concentrate, we chose to perform a non-smooth, second order 231 polynomial regression for preventing any model over-fitting and a spurious age–depth 232 relationship. In addition, we run the depth–age model setting a hiatus at 73 m depth 233 where we think an interruption in the ice accumulation was produced. This idea is 234 supported by the observation of several debris layers that increased their frequency 235 towards the top of the glacier. Those layers are interpreted as the result of several 236 phases of melting, dramatically changing the accumulation rates and concentrating 237 samples of similar ages (see section 4.1 below). Full details on how the model was 238 performed and a reproducible workflow with the current chronological dataset are available in 239 the Supplementary Material. 240 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 9 3.4. Trace elements in soluble and insoluble material. 241 35 selected ice samples from the altitudinal transect were melted and filtered through 242 a filtration ramp connected to a vacuum pump using 47 mm quartz fiber filters (PALL 243 tissuquarzt 2500QAT-UP). Filters were pre-heated at 250 °C and thereafter prepared in 244 controlled conditions (temperature: 22–24 °C; relative humidity: 25–35 %) before and 245 after filtration. Subsequently, they were weighted in two different days. Mass 246 difference between blank and sampled filters was used to calculate the amount of 247 insoluble material entrapped in ice samples. For every sample, an aliquot and a filter 248 were obtained. From aliquots, anions and cations, as well as major and trace elements 249 were determined. From filters, we determined major and trace elements, as well as 250 organic and elemental carbon, following the method devised by (Pey et al., 2013) 251 (Table 2). Basically, an acidic digestion (HNO3:HF:HClO4) of half of each filter was 252 conducted, driven to complete dryness, being the remaining material re-dissolved in 253 HNO3. Inductively coupled plasma mass spectrometry (ICP-MS) and inductively 254 coupled plasma atomic emission spectroscopy (ICP-AES) were used to determine major 255 and trace elements. From the other half of each filter, a 1.5 cm2 section was used to 256 determine Organic Carbon (OC) and Elemental Carbon (EC) concentrations by using a 257 SUNSET thermo-optical analyzer, following the EUSAAR_2 temperature protocol. Table 258 1 also contains the Enrichment Factors (EFs) calculated as follows: 259 260 where EFiCODD is the Al-normalised Enrichment Factor with respect to the Upper Crust 261 (UC, (Taylor and McLennan, 1995)) of an ‘i’ element in the current Ordesa’s deposited 262 dust (CODD); EFiMPGID is the Al-normalised Enrichment Factor with respect to the UC of 263 an ‘i’ element in the current MPG ice dust (MPGID); and EFi is the Al-normalised 264 Enrichment Factor with respect to CODD of an ‘i’ element in the MPGID. 265 Regarding the Pb/Al ratio, we carried out a normalization with Al in both, ice and lake 266 records, to disentangle the anthropogenic lead variability from possible detrital inputs. 267 / / / / EFiCODD = EFiMPGID = / / EFi = https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 16 this period (Fig. 2). We assume that, by this time, basal ice of Neoglacial age was 451 already removed, but at the end of the MCA the MPG still preserved ice from the RP 452 and the first half of the DA (Fig. 4D). 453 Over such a diminished MCA glacier, ice started to accumulate again at a rapid rate 454 during the LIA (1300–1850 CE). In most cases, the LIA was the period when mountain 455 glaciers recorded their maximum Holocene extent (Solomina et al., 2016), with 456 remarkable advances in the alpine glaciers (Ivy-Ochs et al., 2009). From a large variety 457 of proxies, several warm and cold periods have been identified in the Iberian Peninsula 458 during the LIA (Oliva et al., 2018). In the Marboré Cirque two generations of LIA 459 moraines have been mapped (García-Ruiz et al., 2014), whose emplacement coincided 460 with the coldest LIA phases, i.e. 1620-1715 CE, when the Pyrenean glaciers recorded 461 their maximum extent, and 1820-1840 CE, when a rapid advance of the ice mass 462 moved over the large moraine leaving parallel furrows, or flutes, as signs of erosion 463 (García-Ruiz et al., 2020; Serrano and Martín-Moreno, 2018). These two cold phases 464 are very well identified in the Marboré Cirque and were confirmed by the study of the 465 altitudinal fluctuations of the timberline in the neighboring Escuaín Valley (Camarero 466 et al., 2015). In fact, according to the map of Schrader from 1874 CE and other 467 historical sources, the MPG made direct contact with the large moraine in the second 468 half of the 19th century (García-Ruiz et al., 2014). Despite the MPG would have covered 469 an area of 5.56 km2 at the end of the LIA (in 1894, (González Trueba et al., 2008), Fig. 470 4E), there is no record today of ice accumulated during the LIA, except for a few 471 meters at the top of the sequence corresponding to about 1400 CE. This means that 472 more than 600 years of ice accumulation have been lost associated to the warming 473 after ca. 1850 CE. This situation is not so common in the Alps, where ice from the LIA, 474 and even from the last two centuries, is still preserved in many studied glaciers (Eichler 475 et al., 2000; Gabrielli et al., 2016; Gäggeler et al., 1983; Preunkert et al., 2019). 476 Today the MPG is divided in two small ice bodies that together cover just 0.38 km2 477 (López-Moreno et al., 2016, Fig. 4F). Comparing the MPG extent at the end of the LIA 478 (ca. 1850 CE), thanks to the moraine location, and today, more than 5 km2 of MPG 479 would have disappeared, thus indicating that the last 150 years have likely been the 480 period with the largest glacier melting in the last 2000 years. 481 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 17 5. Conclusions 482 This study presents for the first time the chronology of a glacier in the Pyrenees, 483 reconstructed from a set of 14C dates on different organic remains and supported by 484 measurements on current atmospheric deposition and comparison with a nearby lake 485 sequence (Marboré Lake). The ice sequence from MPG covers the last 2000 years 486 allowing defining cold periods of ice advance and warm periods of retreat. We 487 demonstrate that the glacier was active during the RP, a well known warm period in 488 Iberia Peninsula. During the MCA, the MPG experienced a spectacular retreat marked 489 by the presence of dark debris layers indicative of successive years when ablation 490 processes predominated. The LIA was a period of glacier advance but not recorded 491 today in the ice from MPG since more than 600 years of ice accumulation have been 492 lost associated to the warming after ca. 1850 CE. This evidence from the age-depth 493 model is supported by the lack of anthropogenic indicators usually associated to the 494 Industrial Era abundant today in current atmospheric deposition in a nearby site. 495 Additionally, both Hg concentration and Pb/Al ratio appear much higher in the 496 Marboré Lake sediments whereas they don’t reflect the anthropogenic increase in the 497 MPG record. 498 Comparing the present-day glacier situation with that of previous warm intervals, such 499 as the RP or the MCA, we conclude that the MPG is nowadays greatly reduced in area 500 and volume. Additionally, the recent ice mass loss rate is definitely more rapid than 501 during the four centuries spanned by the MCA, thus suggesting that present day 502 warming in the Pyrenees is faster and more intense than in any previous warm phase 503 occurred during the last 2000 years. Under such climatic conditions, it is reasonable to 504 expect the disappearance of this glacier, as well as other glaciers in the Pyrenees and 505 in Southern Europe, over the next few decades. 506 6. Data availability 507 The input data file for CLAM, as well as the output results are stored in this journal for 508 reviewing process and will be permanently deposited in the journal upon the 509 acceptance of this manuscript. The other data are included in the tables and in the 510 Supplementary. 511 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 18 7. Author contributions 512 The paper was conceived by A.M., M.B., C.S. and J.I.L.M. and F.N., J.O.G., J.L., P.G.S., 513 C.C., J. L.M., B.O., S.H.F and J.G.R. contributed to design this research project. J.G.O. 514 carried out the 210Pb and 137Cs analyses; J.P., X.Q. and A.A. provided the geochemical 515 data from Ordesa site and MPG; P.C., M.J.S. and R.M. provided the Hg data from 516 Marboré Lake and MPG, C.P., M.L., E.A. helped during field work and G.G.R. run the R 517 package CLAM 2.2 to build the age model. All authors contributed to the writing of the 518 paper. 519 8. Competing interest 520 The authors declare that they have no conflict of interest. 521 9. Acknowledgements 522 The Spanish Agencia Estatal de Investigación (AEI – Spain) and the European Funds for 523 Regional Development (FEDER – European Union) are gratefully acknowledged for 524 financial support through PaleoICE EXPLORA project (CGL2015-72167-EXP), CGL2015525 68993-R, CGL2015-69160-R and CTM2017-84441-R projects (AEI/FEDER, UE). SHF 526 acknowledges support by the Spanish Government through María de Maeztu 527 excellence accreditation 2018-2022 (MDM-2017-0714) and through the iMechPro 528 RETOS project (RTI2018-100696-B-I00). M.B is supported by postdoctoral fellowship 529 Juan de la Cierva-Formación program provided by the Spanish Ministry (ref.: FJCI-2017530 34235063753). The authors are grateful to Eduardo Bartolomé and José Estebán 531 Lozano for their help manufacturing parts of the coring devices and to the support 532 provided by the “Dirección General de Conservación del Medio Natural (Government 533 of Aragón)” and to the staff of the Ordesa and Monte Perdido National Park during our 534 field campaigns. 535 10. References 536 Blaauw, M.: Methods and code for ‘classical’ age-modelling of radiocarbon sequences, 537 Quaternary Geochronology, 5(5), 512–518, doi:10.1016/j.quageo.2010.01.002, 2010. 538 Blaauw, M., Christen, J. A., Vázquez, J. E. and Goring, S.: clam: Classical Age-Depth Modelling of 539 Cores from Deposits. CRAN 2019, [online] Available from: https://CRAN.R540 project.org/package=clam, 2019. 541 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 19 Büntgen, U., Krusic, P. J., Verstege, A., Sangüesa-Barreda, G., Wagner, S., Camarero, J. J., 542 Ljungqvist, F. C., Zorita, E., Oppenheimer, C., Konter, O., Tegel, W., Gärtner, H., Cherubini, P., 543 Reinig, F. and Esper, J.: New Tree-Ring Evidence from the Pyrenees Reveals Western 544 Mediterranean Climate Variability since Medieval Times, J. Climate, 30(14), 5295–5318, 545 doi:10.1175/JCLI-D-16-0526.1, 2017. 546 Callén, J. J. N.: El proceso sidero-metarlúrgico altoaragonés: los valles de Bielsa y Gistain en la 547 Edad Moderna (1565-1800), Llull: Revista de la Sociedad Española de Historia de las Ciencias y 548 de las Técnicas, 19(37), 471–508, 1996. 549 Camarero, J. J., García-Ruiz, J. M., Sangüesa-Barreda, G., Galván, J. D., Alla, A. Q., Sanjuán, Y., 550 Beguería, S. and Gutiérrez, E.: Recent and Intense Dynamics in a Formerly Static Pyrenean 551 Treeline, Arctic, Antarctic, and Alpine Research, 47(4), 773–783, doi:10.1657/AAAR0015-001, 552 2015. 553 Cisneros, M., Cacho, I., Frigola, J., Canals, M., Masqué, P., Martrat, B., Casado, M., Grimalt, J. 554 O., Pena, L. D., Margaritelli, G. and Lirer, F.: Sea surface temperature variability in the central555 western Mediterranean Sea during the last 2700 years: a multi-proxy and multi-record 556 approach, Clim. Past, 12(4), 849–869, doi:10.5194/cp-12-849-2016, 2016. 557 Cooke, C. A., Martínez-Cortizas, A., Bindler, R. and Sexauer Gustin, M.: Environmental archives 558 of atmospheric Hg deposition – A review, Science of The Total Environment, 709, 134800, 559 doi:10.1016/j.scitotenv.2019.134800, 2020. 560 Corella, J. P., Valero-Garcés, B. L., Wang, F., Martínez-Cortizas, A., Cuevas, C. A. and Saiz-Lopez, 561 A.: 700 years reconstruction of mercury and lead atmospheric deposition in the Pyrenees (NE 562 Spain), Atmospheric Environment, 155, 97–107, doi:10.1016/j.atmosenv.2017.02.018, 2017. 563 Corella, J. P., Saiz-Lopez, A., Sierra, M. J., Mata, M. P., Millán, R., Morellón, M., Cuevas, C. A., 564 Moreno, A. and Valero-Garcés, B. L.: Trace metal enrichment during the Industrial Period 565 recorded across an altitudinal transect in the Southern Central Pyrenees, Science of The Total 566 Environment, 645, 761–772, doi:10.1016/j.scitotenv.2018.07.160, 2018. 567 Corella, J. P., Sierra, M. J., Garralón, A., Millán, R., Rodríguez-Alonso, J., Mata, M. P., Wilhem, 568 B., Vivez, P., Duval, B., Amouroux, D., Vicente de Vera, A., Moreno, A., Cuevas, C. A., Adame, J. 569 A., Saiz-Lopez, A. and Valero Garcés, B.: Legacy pollution from roman and medieval mining in 570 the Iberian Peninsula recorded in high mountain ecosystems, Science of The Total 571 Environment, under review, 2020. 572 Crest, Y., Delmas, M., Braucher, R., Gunnell, Y. and Calvet, M.: Cirques have growth spurts 573 during deglacial and interglacial periods: Evidence from 10Be and 26Al nuclide inventories in 574 the central and eastern Pyrenees, Geomorphology, 278, 60–77, 575 doi:10.1016/j.geomorph.2016.10.035, 2017. 576 Davis, P. T., Menounos, B. and Osborn, G.: Holocene and latest Pleistocene alpine glacier 577 fluctuations: a global perspective, Quaternary Science Reviews, 28(21–22), 2021–2033, 578 doi:10.1016/j.quascirev.2009.05.020, 2009. 579 Eichler, A., Schwikowski, M., Gäggeler, H. W., Furrer, V., Synal, H.-A., Beer, J., Saurer, M. and 580 Funk, M.: Glaciochemical dating of an ice core from upper Grenzgletscher (4200 m a.s.l.), 581 Journal of Glaciology, 46(154), 507–515, doi:10.3189/172756500781833098, 2000. 582 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 20 Ewing, M. E., Reese, C. A. and Nolan, M. A.: The potential effects of percolating snowmelt on 583 palynological records from firn and glacier ice, Journal of Glaciology, 60(222), 661–669, 584 doi:10.3189/2014JoG13J158, 2014. 585 Festi, D., Carturan, L., Kofler, W., dalla Fontana, G., de Blasi, F., Cazorzi, F., Bucher, E., Mair, V., 586 Gabrielli, P. and Oeggl, K.: Linking pollen deposition, snow accumulation and isotopic 587 composition on the Alto dell’Ortles glacier (South Tyrol, Italy) for sub-seasonal dating of a firn 588 temperate core, The Cryosphere Discussions, 1–16, doi:10.5194/tc-2016-221, 2016. 589 Frigola, J., Moreno, A., Cacho, I., Canals, M., Sierro, F. J., Flores, J. A., Grimalt, J. O., Hodell, D. A. 590 and Curtis, J. H.: Holocene climate variability in the western Mediterranean region from a 591 deepwater sediment record, Paleoceanography, 22(doi:10.1029/2006PA001307), 2007. 592 Gabrielli, P., Barbante, C., Bertagna, G., Bertó, M., Binder, D., Carton, A., Carturan, L., Cazorzi, 593 F., Cozzi, G., Dalla Fontana, G., Davis, M., De Blasi, F., Dinale, R., Dragà, G., Dreossi, G., Festi, D., 594 Frezzotti, M., Gabrieli, J., Galos, S. P., Ginot, P., Heidenwolf, P., Jenk, T. M., Kehrwald, N., 595 Kenny, D., Magand, O., Mair, V., Mikhalenko, V., Lin, P. N., Oeggl, K., Piffer, G., Rinaldi, M., 596 Schotterer, U., Schwikowski, M., Seppi, R., Spolaor, A., Stenni, B., Tonidandel, D., Uglietti, C., 597 Zagorodnov, V., Zanoner, T. and Zennaro, P.: Age of the Mt. Ortles ice cores, the Tyrolean 598 Iceman and glaciation of the highest summit of South Tyrol since the Northern Hemisphere 599 Climatic Optimum, The Cryosphere, 10(6), 2779–2797, doi:10.5194/tc-10-2779-2016, 2016. 600 Gäggeler, H., Gunten, H. R. von, Rössler, E., Oeschger, H. and Schotterer, U.: 210Pb-Dating of 601 Cold Alpine Firn/Ice Cores From Colle Gnifetti, Switzerland, Journal of Glaciology, 29(101), 602 165–177, doi:10.1017/S0022143000005220, 1983. 603 García-Ruiz, J. M., Palacios, D., Andrés, N. de, Valero-Garcés, B. L., López-Moreno, J. I. and 604 Sanjuán, Y.: Holocene and ‘Little Ice Age’ glacial activity in the Marboré Cirque, Monte Perdido 605 Massif, Central Spanish Pyrenees, The Holocene, 24(11), 1439–1452, 606 doi:10.1177/0959683614544053, 2014. 607 García-Ruiz, J.M., Palacios, D., Andrés, N., López-Moreno, J.I.: Neoglaciation in the Spanish 608 Pyrenees: A multiproxy challenge. Mediterranean Geoscience Reviews. 609 https://doi.org/10.1007/s42990-020-00022-9, 2020. 610 Garzonio, R., Di Mauro, B., Strigaro, D., Rossini, M., Colombo, R., De Amicis, M. and Maggi, V.: 611 Mapping the suitability for ice-core drilling of glaciers in the European Alps and the Asian High 612 Mountains, J. Glaciol., 64(243), 12–26, doi:10.1017/jog.2017.75, 2018. 613 Gellatly, A. F., Grove, J. M. and Switsur, V. R.: Mid-Holocene glacial activity in the Pyrenees, The 614 Holocene, 2(3), 266–270, doi:10.1177/095968369200200309, 1992. 615 González Trueba, J. J., Moreno, R. M., Martínez de Pisón, E. and Serrano, E.: `Little Ice Age’ 616 glaciation and current glaciers in the Iberian Peninsula, The Holocene, 18(4), 551–568, 617 doi:10.1177/0959683608089209, 2008. 618 Haeberli, W., Frauenfelder, R., Kääb, A. and Wagner, S.: Characteristics and potential climatic 619 significance of “miniature ice caps” (crestand cornice-type low-altitude ice archives), Journal 620 of Glaciology, 50(168), 129–136, doi:10.3189/172756504781830330, 2004. 621 Herren, P.-A., Eichler, A., Machguth, H., Papina, T., Tobler, L., Zapf, A. and Schwikowski, M.: The 622 onset of Neoglaciation 6000 years ago in western Mongolia revealed by an ice core from the 623 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 21 Tsambagarav mountain range, Quaternary Science Reviews, 69, 59–68, 624 doi:10.1016/j.quascirev.2013.02.025, 2013. 625 Holzhauser, H., Magny, M. and Zumbühl, H. J.: Glacier and lake-level variations in west-central 626 Europe over the last 3500 years, The Holocene, 15(6), 789–801, 2005. 627 Hughes, P. D.: Little Ice Age glaciers and climate in the Mediterranean mountains: a new 628 analysis, CIG, 44(1), 15, doi:10.18172/cig.3362, 2018. 629 Ivy-Ochs, S., Kerschner, H., Maisch, M., Christl, M., Kubik, P. W. and Schlüchter, C.: Latest 630 Pleistocene and Holocene glacier variations in the European Alps, Quaternary Science Reviews, 631 28(21–22), 2137–2149, 2009. 632 Jenk, T. M., Szidat, S., Bolius, D., Sigl, M., Gäggeler, H. W., Wacker, L., Ruff, M., Barbante, C., 633 Boutron, C. F. and Schwikowski, M.: A novel radiocarbon dating technique applied to an ice 634 core from the Alps indicating late Pleistocene ages, Journal of Geophysical Research: 635 Atmospheres, 114(D14), doi:10.1029/2009JD011860, 2009. 636 Leunda, M., González-Sampériz, P., Gil-Romera, G., Aranbarri, J., Moreno, A., Oliva-Urcia, B., 637 Sevilla-Callejo, M. and Valero-Garcés, B.: The Late-Glacial and Holocene Marboré Lake 638 sequence (2612m a.s.l., Central Pyrenees, Spain): Testing high altitude sites sensitivity to 639 millennial scale vegetation and climate variability, Global and Planetary Change, 157, 214–231, 640 doi:10.1016/j.gloplacha.2017.08.008, 2017. 641 López-Moreno, J. I., Revuelto, J., Rico, I., Chueca-Cía, J., Julián, A., Serreta, A., Serrano, E., 642 Vicente-Serrano, S. M., Azorin-Molina, C., Alonso-González, E. and García-Ruiz, J. M.: Thinning 643 of the Monte Perdido Glacier in the Spanish Pyrenees since 1981, The Cryosphere, 10(2), 681– 644 694, doi:10.5194/tc-10-681-2016, 2016. 645 López-Moreno, J. I., Alonso-González, E., Monserrat, O., Del Río, L. M., Otero, J., Lapazaran, J., 646 Luzi, G., Dematteis, N., Serreta, A., Rico, I., Serrano-Cañadas, E., Bartolomé, M., Moreno, A., 647 Buisan, S. and Revuelto, J.: Ground-based remote-sensing techniques for diagnosis of the 648 current state and recent evolution of the Monte Perdido Glacier, Spanish Pyrenees, J. Glaciol., 649 65(249), 85–100, doi:10.1017/jog.2018.96, 2019. 650 Mann, M. E., Zhang, Z., Rutherford, S., Bradley, R. S., Hughes, M. K., Shindell, D., Ammann, C., 651 Faluvegi, G. and Ni, F.: Global Signatures and Dynamical Origins of the Little Ice Age and 652 Medieval Climate Anomaly, Science, 326(5957), 1256–1260, 2009. 653 Martín-Puertas, C., Jiménez-Espejo, F., Martínez-Ruiz, F., Nieto-Moreno, V., Rodrigo, M., Mata, 654 M. P. and Valero-Garcés, B. L.: Late Holocene climate variability in the southwestern 655 Mediterranean region: an integrated marine and terrestrial geochemical approach, Clim. Past, 656 6(6), 807–816, doi:10.5194/cp-6-807-2010, 2010. 657 Marzeion, B., Cogley, J. G., Richter, K. and Parkes, D.: Attribution of global glacier mass loss to 658 anthropogenic and natural causes, Science, 345(6199), 919–921, 659 doi:10.1126/science.1254702, 2014. 660 Moore, P. D., Webb, J. A. and Collinson, M. E.: Pollen Analysis, Second., Blackwell Scientific 661 Publications., 1991. 662 Morellón, M., Valero-Garcés, B., Vegas-Vilarrúbia, T., González-Sampériz, P., Romero, Ó., 663 Delgado-Huertas, A., Mata, P., Moreno, A., Rico, M. and Corella, J. P.: Lateglacial and Holocene 664 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 22 palaeohydrology in the western Mediterranean region: The Lake Estanya record (NE Spain), 665 Quaternary Science Reviews, 28(25–26), 2582–2599, 2009. 666 Nieto-Moreno, V., Martínez-Ruiz, F., Giralt, S., Jiménez-Espejo, F., Gallego-Torres, D., Rodrigo667 Gámiz, M., García-Orellana, J., Ortega-Huertas, M. and de Lange, G. J.: Tracking climate 668 variability in the western Mediterranean during the Late Holocene: a multiproxy approach, 669 Clim. Past Discuss., 7(1), 635–675, doi:10.5194/cpd-7-635-2011, 2011. 670 Oerlemans, J.: Glaciers and Climate Change, CRC Press., 2001. 671 Oliva, M., Ruiz-Fernández, J., Barriendos, M., Benito, G., Cuadrat, J. M., Domínguez-Castro, F., 672 García-Ruiz, J. M., Giralt, S., Gómez-Ortiz, A., Hernández, A., López-Costas, O., López-Moreno, 673 J. I., López-Sáez, J. A., Martínez-Cortizas, A., Moreno, A., Prohom, M., Saz, M. A., Serrano, E., 674 Tejedor, E., Trigo, R., Valero-Garcés, B. and Vicente-Serrano, S. M.: The Little Ice Age in Iberian 675 mountains, Earth-Science Reviews, 177, 175–208, doi:10.1016/j.earscirev.2017.11.010, 2018. 676 Oliva-Urcia, B., Moreno, A., Leunda, M., Valero-Garcés, B., González-Sampériz, P., Gil-Romera, 677 G., Mata, M. P. and Group, H.: Last deglaciation and Holocene environmental change at high 678 altitude in the Pyrenees: the geochemical and paleomagnetic record from Marboré Lake (N 679 Spain), J Paleolimnol, 59(3), 349–371, doi:10.1007/s10933-017-0013-9, 2018. 680 Palacios, D., García-Ruiz, J. M., Andrés, N., Schimmelpfennig, I., Campos, N., Léanni, L., 681 Aumaître, G., Bourlès, D. L. and Keddadouche, K.: Deglaciation in the central Pyrenees during 682 the Pleistocene–Holocene transition: Timing and geomorphological significance, Quaternary 683 Science Reviews, 162, 111–127, doi:10.1016/j.quascirev.2017.03.007, 2017. 684 Pey, J., Pérez, N., Cortés, J., Alastuey, A. and Querol, X.: Chemical fingerprint and impact of 685 shipping emissions over a western Mediterranean metropolis: Primary and aged contributions, 686 Science of The Total Environment, 463–464, 497–507, doi:10.1016/j.scitotenv.2013.06.061, 687 2013. 688 Preunkert, S., McConnell, J. R., Hoffmann, H., Legrand, M., Wilson, A. I., Eckhardt, S., Stohl, A., 689 Chellman, N. J., Arienzo, M. M. and Friedrich, R.: Lead and Antimony in Basal Ice From Col du 690 Dome (French Alps) Dated With Radiocarbon: A Record of Pollution During Antiquity, 691 Geophysical Research Letters, 46(9), 4953–4961, doi:10.1029/2019GL082641, 2019. 692 Querol, X., Viana, M., Alastuey, A., Amato, F., Moreno, T., Castillo, S., Pey, J., de la Rosa, J., 693 Sánchez de la Campa, A., Artíñano, B., Salvador, P., García Dos Santos, S., Fernández-Patier, R., 694 Moreno-Grau, S., Negral, L., Minguillón, M. C., Monfort, E., Gil, J. I., Inza, A., Ortega, L. A., 695 Santamaría, J. M. and Zabalza, J.: Source origin of trace elements in PM from regional 696 background, urban and industrial sites of Spain, Atmospheric Environment, 41(34), 7219–7231, 697 doi:10.1016/j.atmosenv.2007.05.022, 2007. 698 Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Ramsey, C. B., Buck, C. E., Cheng, 699 H., Edwards, R. L., Friedrich, M. and others: IntCal13 and Marine13 radiocarbon age calibration 700 curves 0–50,000 years cal BP, Radiocarbon, 55(4), 1869–1887, 2013. 701 Rico, I., Izagirre, E., Serrano, E. and López-Moreno, J. I.: Superficie glaciar actual en los Pirineos: 702 Una actualización para 2016, Pirineos, 172(0), 029, doi:10.3989/Pirineos.2017.172004, 2017. 703 Salazar, A., Mata, M. P., Rico, M., Valero-Garcés, Oliva-Urcia, B. and Rubio, F. M.: El paleolago 704 de La Larri (Valle de Pineta, Pirineos), Cuadernos de Investigación Geográfica, 39(1), 97–116, 705 2013. 706 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 23 Sanchez-Cabeza, J. A., Masqué, P. and Ani-Ragolta, I.: 210Pb and210Po analysis in sediments 707 and soils by microwave acid digestion, J Radioanal Nucl Chem, 227(1), 19–22, 708 doi:10.1007/BF02386425, 1998. 709 Serrano, E. and Martín-Moreno, R.: Surge glaciers during the Little Ice Age in the Pyrenees, 710 Cuadernos de Investigación Geográfica, 44(1), 213–244, doi:10.18172/cig.3399, 2018. 711 Solomina, O. N., Bradley, R. S., Hodgson, D. A., Ivy-Ochs, S., Jomelli, V., Mackintosh, A. N., 712 Nesje, A., Owen, L. A., Wanner, H., Wiles, G. C. and Young, N. E.: Holocene glacier fluctuations, 713 Quaternary Science Reviews, 111, 9–34, doi:10.1016/j.quascirev.2014.11.018, 2015. 714 Solomina, O. N., Bradley, R. S., Jomelli, V., Geirsdottir, A., Kaufman, D. S., Koch, J., McKay, N. P., 715 Masiokas, M., Miller, G., Nesje, A., Nicolussi, K., Owen, L. A., Putnam, A. E., Wanner, H., Wiles, 716 G. and Yang, B.: Glacier fluctuations during the past 2000 years, Quaternary Science Reviews, 717 149, 61–90, doi:10.1016/j.quascirev.2016.04.008, 2016. 718 Taylor, S. R. and McLennan, S. M.: The geochemical evolution of the continental crust, Reviews 719 of Geophysics, 33, 241–265, 1995. 720 Thompson, L. G., Mosley-Thompson, E., Brecher, H., Davis, M., Leon, B., Les, D., Lin, P.-N., 721 Mashiotta, T. and Mountain, K.: Abrupt tropical climate change: Past and present, Proceedings 722 of the National Academy of Sciences, 103(28), 10536–10543, doi:10.1073/pnas.0603900103, 723 2006. 724 Uglietti, C., Zapf, A., Jenk, T. M., Sigl, M., Szidat, S., Salazar, G. and Schwikowski, M.: 725 Radiocarbon dating of glacier ice: overview, optimisation, validation and potential, The 726 Cryosphere, 10(6), 3091–3105, doi:10.5194/tc-10-3091-2016, 2016. 727 Wanner, H., Solomina, O., Grosjean, M., Ritz, S. P. and Jetel, M.: Structure and origin of 728 Holocene cold events, Quaternary Science Reviews, 30(21–22), 3109–3123, 729 doi:10.1016/j.quascirev.2011.07.010, 2011. 730 Zemp, M., Frey, H., Gärtner-Roer, I., Nussbaumer, S. U., Hoelzle, M., Paul, F., Haeberli, W., 731 Denzinger, F., Ahlstrøm, A. P., Anderson, B., Bajracharya, S., Baroni, C., Braun, L. N., Cáceres, B. 732 E., Casassa, G., Cobos, G., Dávila, L. R., Granados, H. D., Demuth, M. N., Espizua, L., Fischer, A., 733 Fujita, K., Gadek, B., Ghazanfar, A., Hagen, J. O., Holmlund, P., Karimi, N., Li, Z., Pelto, M., Pitte, 734 P., Popovnin, V. V., Portocarrero, C. A., Prinz, R., Sangewar, C. V., Severskiy, I., Sigurđsson, O., 735 Soruco, A., Usubaliev, R. and Vincent, C.: Historically unprecedented global glacier decline in 736 the early 21st century, Journal of Glaciology, 61(228), 745–762, doi:10.3189/2015JoG15J017, 737 2015. 738 Zemp, M., Huss, M., Thibert, E., Eckert, N., McNabb, R., Huber, J., Barandun, M., Machguth, H., 739 Nussbaumer, S. U., Gärtner-Roer, I., Thomson, L., Paul, F., Maussion, F., Kutuzov, S. and Cogley, 740 J. G.: Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016, 741 Nature, 568(7752), 382–386, doi:10.1038/s41586-019-1071-0, 2019. 742 743 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 24 744 745 746 Figure 1. (left) Location of Monte Perdido Glacier (MPG) within a digital elevation map 747 of Marboré Cirque. (right) Picture (©Google Earth) of MPG where the location of the 748 samples is indicated. Note the different orientation of both figures. 749 750 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License. 25 751 752 Figure 2. Composite depth-age model for the Monte Perdido ice sequence based on 753 linear interpolation of 14C data (Table 1), obtained using the Clam software (Blaauw, 754 2010; Blaauw et al., 2019). The dates appear as the calendar-age probability 755 distributions in blue, while the black line is the resulting depth-age model and the gray 756 envelope shows the 95% confidence interval. Note the hiatus located at 73m indicated 757 by a dashed line. 758 759 https://doi.org/10.5194/tc-2020-107 Preprint. Discussion started: 8 June 2020 c Author(s) 2020. CC BY 4.0 License.