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Previous paleo-glacial studies on Kerguelen showed a singular pattern of Holocene glacier evolution on this archipelago in comparison with other southern mid-latitude glacier records. In this study, we aim to test this singularity on a longer timescale, based on 26 new in situ -produced 36Cl ages from pre-Holocene glacio-geomorphic features. Samples from moraine boulders and glacially polished bedrock were extracted at six different sites, located near the Port-aux-Français scientific station (PAF site), on Longue Island, Australia Island, on the Port-Jeanne d'Arc Peninsula (PJDA site), on the Gallieni Peninsula at Baie Larose (BLR site) and the McMurdo Island. The moraine ages indicate that glacier culminations occurred during Marine Isotopic Stage 3 (MIS 3) at 42.2 ± 4.9 ka on the PAF site, and during the global Last Glacial Maximum (gLGM) at 21.5 ± 3.2 ka on the PJDA site and at 21.4 ± 3.7 ka and 19.4 ± 2.6 on Baie Larose site. This is the first time that Late Pleistocene glacier culminations are evidenced on Kerguelen by direct moraine dating, thus allowing comparison with other moraine records from the southern mid-latitudes. While it remains speculative whether or not the MIS 3 glacial maximum at ⁓42.2 ka is in phase with other glaciers at this latitude (due to high age uncertainties), the gLGM glacial maximum is synchronous with that in other southern mid-latitude regions. 36Cl CRE ages of glacially polished bedrock surfaces sampled in different locations of the archipelago vary from ⁓39 ka to ⁓19 ka. We interpret these results as reflecting periods of deglaciation that occurred in between the two glacier culminations and right after the gLGM on Kerguelen. These ages also suggest that some places of the archipelago were free of ice at least since ⁓ 39 ka. The presence of a MIS 3 moraine at PAF site that has not been obliterated by a gLGM advance suggests that the ⁓ 42.2 ka glacier extent was at least as large as gLGM glacial maxima on the archipelago. The glacier culmination during MIS 3 being larger than that during the gLGM on the Kerguelen Archipelago matches observations in other southern mid-latitude regions. Late Pleistocene glacier culminations on Kerguelen may have been in phase with cold temperatures recorded in SST records, which suggest a cooling around Kerguelen. However, climate drivers responsible for the larger MIS 3 glacier culmination on Kerguelen still remain unclear even if we hypothesize that changes in precipitation may have superimposed on temperature changes. • We investigate glacier evolution on the Kerguelen Archipelago for the past 45 ka. • Glacier chronologies are based on 26 new 36Cl ages from moraines and bedrocks. • Preserved moraines attest to glacier culminations at ∼42 ka and during the LGM. • Evidence of larger MIS 3 than gLGM glacier culmination. • This pattern matches records from other southern mid-latitude regions. [ABSTRACT FROM AUTHOR]

Abstract The Tibetan Plateau and its surrounding mountains exhibit the largest concentration of glaciers at lower latitudes on earth, providing source water for the large river systems in Asia. However, glacier observations in this region are short and scarce and hence limit a better understanding of glacier behaviors under a warming climate and thereto coupled processes. The purpose of this research is to investigate the potential and the uncertainty for using pioneering trees on glacial deposits/glacier forefields as a proxy record for past glacier fluctuations in the Himalaya-Nyanqentanggula-Hengduan (H2N) area. It was found that Hippophae tibetana spent 4 years to colonize the glacier forefields at Hailuogou glacier and Pinus wallichiana germinated 11 years after glacier retreating at Gangapuna and Raikot glaciers. At deposit sites of glacier avalanche and glacial lake outburst, it took 8 years for Larix griffithii to germinate after the historical events. As shown by bootstrap resampling, the precision of the sampled maximum tree age could reach 2–14 years, which is related to the sample size to ensure the possibility of obtaining the eldest trees. However, if using the traditional sampling method at 100-cm height, errors of tree age estimation may reach up to ±20 years due to uncertainties of pith offset estimation and height-age calibration. If samples are collected with pith from ≤20 cm tree height, an error of <5 years in tree age estimation could be derived. These results suggest that maximum tree ages may be a promising proxy record of glacier fluctuation with decadal precision in the H2N mountain range if the sample-collecting methods are rigidly controlled and the old trees are well replicated. The uncertainties due to the pith offset, tree height age and sample size imply that cautions should be taken when integrating exposure age dating on decadal-multidecadal glacier fluctuations at regional to hemispheric scales. Highlights • Fast (4–11 years) colonization on glacial area by pioneer trees on the Tibetan Plateau • Decadal precision dating on glacier deposits is possible by tree records. • Collecting samples with pith from height ≤20 cm is recommended. • Dating uncertainty due to sample size and sampling methods should be considered. [ABSTRACT FROM AUTHOR]

Abstract Mountain glaciers and ice caps (GIC) independent of the Greenland Ice Sheet respond rapidly to climate variations and records of their past extent provide information on the natural envelope of climate variability. Here, we use a multi-proxy approach that combines proglacial lake sediment analysis, cosmogenic nuclide surface-exposure dating (in situ 10Be and 14C), and radiocarbon dating of recently ice-entombed moss to generate a centennial-scale record of Holocene GIC fluctuations in southwestern Greenland. Following local deglaciation ∼10-9 ka, sediments from proglacial Crash Lake record a glacier advance at ∼9 ka that is indistinguishable from nearby ice sheet moraines, implying a synchronous response of GIC and the Greenland Ice Sheet to a centennial-scale climate event. Following this local glacier advance, GIC experienced net recession until ∼4.6 ka. Radiocarbon ages of in situ moss (n = 29) and Crash Lake sediments reveal intervals of glacier expansion at ∼1.8, 1.2 and 0.7 ka that are superimposed on an overall trend of net glacier expansion throughout the late Holocene. In situ 14C concentrations from bedrock adjacent to radiocarbon-dated moss samples further constrain the duration of ice cover through the Holocene in this region. We find that our glacier-size proxy records during the past ∼4 ka are broadly consistent with relatively lower temperatures recorded in GISP2 and occur during, or following, intervals of volcanic perturbations. Thus, we speculate that volcanic activity, although less frequent and intense than in the early Holocene and during the Little Ice Age, may have led to centennial-scale variability imprinted on net glacier expansion due to decreasing summer insolation through the late Holocene. Highlights • Multiple proxies record Holocene local glacier fluctuations in southwest Greenland. • Local glaciers advanced synchronously with the Greenland Ice Sheet margin at ∼9 ka. • Glacier regrowth at 4.6 ka with successive glacier expansion at 1.8, 1.2 and 0.7 ka. • Late Holocene glacier advances are coeval with reduced temperatures and increased sea ice. [ABSTRACT FROM AUTHOR]

Documenting sub-Antarctic glacier variations during the local last glacial maximum is of major interest to better understand their sensitivity to atmospheric and oceanic temperature changes in conjunction with Antarctic ice sheet changes. However, data are sparse because evidence of earlier glacier extents is for most sub-Antarctic islands located offshore making their observation complex. Here, we present 22 cosmogenic 36 Cl surface exposure ages obtained from five sites at Kerguelen to document the glacial history. The 36 Cl ages from roche moutonnee surfaces, erratics and boulders collected on moraines span from 41.9 ± 4.4 ka to 14.3 ± 1.1 ka. Ice began to retreat on the eastern part of the main island before 41.4 ± 4.4 ka. Slow deglaciation occurred from ∼41 to ∼29 ka. There is no evidence of advances between 29 ka and the Antarctic Cold Reversal (ACR) period (∼14.5–12.9 ka) period. During the ACR, however, the Bontemps and possibly Belvedere moraines were formed by the advance of a Cook Ice Cap outlet glacier and a local glacier on the Presque Ile Jeanne d’Arc, respectively. This glacier evolution differs partly from that of glaciers in New Zealand and in Patagonia. These asynchronous glacier changes in the sub-Antarctic region are however in agreement with sea surface temperature changes recorded around Antarctica, which suggest differences in the climate evolution of the Indo-Pacific and Atlantic sectors of Antarctica. [ABSTRACT FROM AUTHOR]

The importance of glaciers for providing runoff is reflected in the extensive glacier measurement record for China. In this paper, we summarized the mass-balance and front-variation data of glaciers in China that have long-term records. Mass balance has been measured for 22 glaciers; length (or front-position) records exist for 96 glaciers. We found that the mean rate of glacial mass balance decreased by −0.015 m w.e. (water equivalent) per year during the period 1959–2015, which was lower than that for glaciers globally (−0.013 m w.e. per year). It was indicated that the rate of glacial melting (mass loss) increased in China, which was higher than that in glaciers worldwide. However, glacial frontal positions varied among mountains in time and space. Glaciers in the Karakoram Mountains mean advanced 379 m during the 1968–2000 period, while glaciers in the Pamir Mountains remained relatively stable from the 1960s through the 2000s, i.e., retreated 28 m. Glaciers in Hengduan Mountains retreated farthest (1250 m maximum) from 1930 to 2005. [ABSTRACT FROM AUTHOR]

Accelerating ice loss during recent years has made the Greenland Ice Sheet one of the largest single contributors to global sea level rise, accounting for 0.5 of the total 3.2 mm yr −1 . This loss is predicted to continue and will most likely increase in the future as a consequence of global warming. However, the sensitivity of glaciers and ice caps (GICs) in Greenland to prolonged warm periods is less well constrained and geological records documenting the long-term glacial history are needed to put recent observations into a broader perspective. Here we report the results from three proglacial lakes where fluctuations in local glaciers located at different altitudes in Kobbefjord, southwest Greenland have been recorded. Our results show that the lakes received meltwater from the initial deglaciation of the area ∼9.2 cal. ka BP until ∼8.7–7.9 cal. ka BP when the meltwater input ceased as the glaciers most likely disappeared. Regrowth of glaciers began again at ∼5.5 cal. ka BP at ∼1370 m a.s.l., ∼3.6 cal. ka at ∼1170 m a.s.l., and ∼1.6 cal. ka BP at ∼1000 m a.s.l., clearly reflecting strong altitudinal control of the GIC response to Neoglacial cooling. Our results highlight that GICs in Kobbefjord, southwest Greenland are primarily influenced by changes in summer air temperatures and winter precipitation and that they are facing a rapid decay that most likely will result in their disappearance within the next centuries as a consequence of global warming. If current 21st Century retreat rates continue, the GICs in the study area will be completely gone in ∼30–90 years, with the smallest GICs disappearing first. [ABSTRACT FROM AUTHOR]

Similar to many other regions in the world, glaciers in the southern sub-polar regions are currently retreating. In the Kerguelen Islands (49°S, 69°E), the mass balance of the Cook Ice Cap (CIC), the largest ice cap in this region, experienced dramatic shrinking between 1960 and 2013 with retreat rates among the highest in the world. This observation needs to be evaluated in a long-term context. However, data on the past glacier extents are sparse in the sub-Antarctic regions. To investigate the deglaciation pattern since the Last Glacial Maximum (LGM) period, we present the first 13 cosmogenic 36 Cl surface exposure ages from four sites in the Kerguelen Islands. The 36 Cl ages from erratic and moraine boulders span from 24.4 ± 2.7 ka to 0.3 ± 0.1 ka. We combined these ages with existing glacio-marine radiocarbon ages and bathymetric data to document the temporal and spatial changes of the island's glacial history. Ice began to retreat on the main island before 24.4 ± 2.7 ka until around the time of the Antarctic Cold Reversal (ACR) period (∼14.5–12.9 ka), during which the Bontemps moraine was formed by the advance of a CIC outlet glacier. Deglaciation continued during the Holocene probably until 3 ka with evidence of minor advances during the last millennium. This chronology is in pace with major changes in δ 18 O in a recent West Antarctica ice core record, showing that Kerguelen Islands glaciers are particularly sensitive and relevant to document climate change in the southern polar regions. [ABSTRACT FROM AUTHOR]

[Display omitted] • 100 years of mass balance and climatic analysis for the lowermost Italian glacier. • Lower degree of imbalance compared to other European glaciers. • Glacier behavior progressively decoupled from atmospheric warming due to debris cover. Small, debris-covered and avalanche-fed glaciers are widespread in high-relief areas of the world. However, their climatic response is poorly known because they cannot be investigated with 'traditional' techniques, like the glaciological mass-balance method, and long-term observations series are very rare. This work documents changes in elevation, mass balance rate and surface cover in the last century (from 1920 to 2020) for the small, debris-covered and avalanche-fed Montasio Glacier, where recent investigations show unusual response to climatic changes, but it is unclear whether this response is a short- or a long-term characteristic. Glacier response is analysed primarily through Digital Elevation Models reconstructed from different types of data sources (maps, terrestrial and aerial images, point clouds). Glacier changes are analysed jointly with trends in the most relevant climatic variables. The glacier experienced phases of rapid mass loss between 1920 and 1948 (−0.49 m w.e. y-1) and between 1982 and 2006 (−0.36 m w.e. y-1). Smaller imbalance occurred between 1948 and 1982 (−0.14 m w.e. y-1) and, remarkably, between 2006 and 2020 (−0.03 m w.e. y-1). Whereas the 1948–1982 was a favourable time-window for most glaciers in the Alps, the last fifteen years were characterized by rapid warming and show a clear divergence between the behaviour of the Montasio Glacier and of the rest of Alpine glaciers. A century-long increase in debris cover, now 2–3 m thick in the lower half of the glacier, explains largely this divergence. Snow-rich winters in recent years also played a role, because the glacier reacts sensitively to changes in solid precipitation. Even in the case of possible decreased snowfalls and increased melt associated with warming temperatures during the next decades, the glacier is not expected to vanish soon, because it will likely survive under a thick layer of debris and shadowed by the north walls of the Mount Jôf di Montasio. On the other hand, the results of this study, paired with the current distribution of permafrost in the study area, suggest that the Montasio Glacier will unlikely evolve into a rock glacier or a glacial-permafrost composite landform. [ABSTRACT FROM AUTHOR]

Cosmic-ray exposure (CRE) dating of moraines allow glacier fluctuations and past climate change reconstructions. In the French Alps, there is a lack of moraine dating for the Late Glacial/Holocene transition period. Here we present a chronology of glacier advances in the Upper Romanche valley (French Alps – Massif des Ecrins) based on 10 Be CRE dating. CRE ages of moraines of 13.0 ± 1.1 ka and 12.4 ± 1.5 ka provide evidence for two stages of glacial advance or standstill at the end of the Late Glacial. The CRE dating of a rock avalanche deposit at 12.2 ± 1.5 ka is attributed to post-glacial debuttressing and reveals rapid deglaciation at the end of the Late Glacial. A CRE age of 7.1 ± 0.7 ka of a second mass-wasting, whose triggering factor is unidentified so far, indicates that up to an altitude of 2300 m a.s.l., the valley was ice-free as of ∼7 kyr at the latest. The re-evaluation of 21 moraine 10 Be CRE ages from nine glacial valleys across the Alps shows multiple glacial advances occurring at the Late Glacial/Holocene transition. These results lead to a re-evaluation of the importance of cooling events during the Allerød and the Younger Dryas in the Alps. [ABSTRACT FROM AUTHOR]

In the Northern Caucasus, glacier and climatic variations over the past centuries remain insufficiently documented. In this review, we summarized the high-resolution information on glacier and climate fluctuations in the region for the past millennium and provided a synthesis of these two lines of evidence with respect to regional climate change. The key areas considered in the paper are the Elbrus area, the Teberda and Arkhyz valleys in the Western Caucasus and the Cherek Bezengiisky and Tsey valleys in the Eastern Caucasus, where the most paleoclimatic evidence has been retrieved. We focused on the fluctuation records of the ten glaciers that are best documented. To reconstruct changes in glacier length in the past, we used aerial photos, optical space images, repeated photographs and old maps. The ages of moraines were defined with the help of instrumental records, historical images, old maps, and tree-ring dating. Lichenometry was used as a supplementary tool to determine the relative ages of glacial landforms. We reviewed the collection of control points used for the lichenometric curves and determined the time limit of potential use of this method in the Caucasus to be up to one millennium. High-resolution tree-ring-based hydroclimatic reconstructions in the Northern Caucasus are presented based on the reconstruction of June–September temperature (1595–2012 CE), the mass balance reconstruction of the Garabashi Glacier (1800–2008 CE) and the runoff of the Teberda River (low-frequency variations) for May, July and August for 1850–2005 CE. The synthesis of all the available paleoclimatic records revealed several distinct climatic periods. Evidence of a warm interval (traditionally referred to as the “Arkhyz break in glaciation”) preceding the Little Ice Age (LIA) in the Caucasus is based on archeological, palynological, geochemical and pedological data. However, the conclusions concerning the duration and magnitude of this warming are still vague due to the low resolution of the data available and ambiguous interpretation of the evidence. The first LIA maximum glacier extent in the past millennium is poorly constrained. According to our data, it occurred prior to the year 1598 CE (tree-ring-based minimum age). Two other major phases of advances occurred in the second half of the 17th century CE and the first half of 19th century CE. General glacier retreat in the Northern Caucasus started in the late 1840s CE, with four to five minor readvances in the 1860s–1880s CE and three readvances or steady states in the 20th century CE (1910s, 1920s and 1970s–1980s). Since the last LIA maximum in the middle of the 19th century CE, most glaciers have decreased in length by more than 1000 m, and the rise in the elevation of the glacier fronts has exceeded 200 m. The glacier advances correspond to summer temperature minima and are generally coherent with the reconstructed mass balance of the Garabashi Glacier. A comparison of a tree-ring-based summer temperature reconstruction in the Northern Caucasus with detailed reconstructions of summer temperature and glacier fluctuations in the Alps shows a pronounced agreement between the records and supports the similarity between the patterns of climatic and glacier variations in the two regions. [ABSTRACT FROM AUTHOR]

Cosmogenic nuclide dating of glacial landforms on the Kerguelen Archipelago (49°S, 69°E) gives the opportunity to study multi-millennial glacier fluctuations within the sub-Antarctic sector of the Indian Ocean. We here dated such geomorphic features to provide time constraints over the last 17,000 years using in situ -produced 36Cl in three glacial valleys: Val Travers valley, Ampere Glacier valley and Arago Glacier valley. For the first time, a combination of in situ- produced 36Cl and 10Be dating and 26Al/10Be ratios analysis was performed in the quartz-bearing syenite boulders of the Arago Glacier site. In addition, a Bayesian approach was computed to obtain a better constraint on moraine dating. Glacial advances occurred during the Late Glacial at 16.0 ± 1.9 ka and at 12.9 ± 1.7 ka in Val Travers, and at 13.6 ± 1.8 ka in Arago Glacier valley, probably linked to the Heinrich Stadial 1 and/or Antarctic Cold Reversal events, respectively. This suggests that all glaciers at this latitude were broadly sensitive to the large-scale climatic signal of the Antarctic Cold Reversal. So far, no Early nor Mid-Holocene moraines have been found in the glacial valleys on Kerguelen, indicating that the glaciers had probably receded significantly during these periods. This is in agreement with previously determined 14C ages from peat bogs, which suggest extensive deglaciation during several millennia of the Holocene period. Samples from glacially-polished bedrock surfaces (ranging from ∼4.4 ka to ∼14 ka) at Ampere Glacier site also suggest that this valley was ice free for several millennia during the Holocene. Finally, glaciers seem to have re-advanced only during the Late Holocene, especially within the last millennium, at ∼1 ka, ∼ 430 yr and ∼300 yr. A comparison of this new dataset with the available 10Be ages from other southern mid-latitude regions during the Holocene allows the identification of three different glacier evolution patterns. We suspect that variations of Kerguelen glaciers, which are located in the Southern Indian Ocean, were controlled by the combined effects of sea surface temperature related to the variations of the Antarctic Polar Front and fluctuations of precipitation related to long-term variations of the Southern Annular Mode. • First 36Cl, 10Be and 26Al dating in quartz-bearing syenites. • Evidence of Heinrich Stadial 1 and Antarctic Cold Reversal advances is provided. • Holocene maximal glacier extent occurred during the Late Holocene. • Non-homogeneous glacier evolution during the Holocene in sub-Antarctic region. • Kerguelen Holocene glaciers' behaviour differs from other sub-Antarctic regions. [ABSTRACT FROM AUTHOR]

Abstract: The amplitude and timing of past glacier culminations are sensitive recorders of key climate events on a regional scale. Precisely dating young moraines using cosmogenic nuclides to investigate Holocene glacier chronologies has proven challenging, but progress in the high-sensitivity 10Be technique has recently been shown to enable the precise dating of moraines as young as a few hundred years. In this study we use 10Be moraine dating to reconstruct culminations of the Steingletscher, a small mountain glacier in the central Swiss Alps, throughout the Holocene. The outermost-recorded positions of Steingletscher most likely occurred in the Early Holocene and appear nearly synchronous with glacier culminations reported from other regions in the Alps. A Late-Holocene position corroborates the evidence for a significant glacier advance of similar extent to that of the Little Ice Age (LIA) ago. Finally, fourteen boulders from different moraines yield 10Be ages between 580 and 140 years with analytical precisions mostly , dating Steingletscher advances during the LIA. Because these LIA 10Be ages are in stratigraphic order, we tentatively distinguish four LIA glacier culminations: about 1470 CE, 1650 CE, 1750 CE and 1820 CE, which are in good agreement with existing independent records during the LIA in the Swiss Alps. These findings illustrate the high potential of the 10Be moraine dating method to directly link paleo-glacier-chronologies to historical records and thus present-day glacier evolution. [Copyright &y& Elsevier]

Records of past glacier fluctuations are an important source of paleoclimate data and provide context for future changes in global ice volume. In the North Atlantic region, glacier chronologies can be used to track the response of terrestrial environments to variations in marine conditions including circulation patterns and sea ice cover. However, the majority of glacier records are discontinuous and temporally restricted, owing in part to the extensive advance of Northern Hemisphere glaciers during the Little Ice Age (LIA), the most recent and severe climate anomaly of the Neoglacial period. Here, we combine an absolutely dated and continuous record of Langjökull ice marginal fluctuations with new reconstructions of sediment flux through the past 1.2 ka using varved sediments from Hvítárvatn, a proglacial lake in Icelandʼs central highlands. Large spatial and temporal variations in sediment flux related to changing ice cap dimensions are reconstructed from six sediment cores and seismic reflection profiles. Sediment data reveal two discrete phases of ice expansion occurring ca. 1400 to 1550 AD and ca. 1680 to 1890 AD. These advances are separated by a persistent interval of ice retreat, suggesting that a substantial period of warming interrupted LIA cold. The pattern of Icelandic glacier activity contrasts with that of European glaciers but shows strong similarities to reconstructed changes in North Atlantic oceanographic conditions, indicating differing regional responses to coupled ocean–atmosphere–sea ice variations. Our data suggest that subpolar North Atlantic circulation dynamics may have led to coherent asynchronous glacier fluctuations during the mid LIA and highlight the importance of circulation variability in triggering and transmitting multidecadal scale climate changes to nearby terrestrial environments. [ABSTRACT FROM AUTHOR]

Abstract: Some researchers propose that summer insolation controls long-term changes in glacier extent during the Holocene. If this hypothesis is correct, the record of glacier fluctuations at high latitudes in the Southern Hemisphere should differ from that in the Northern Hemisphere. Although the chronology of Holocene glacier fluctuations in the Northern Hemisphere is well established, much uncertainty remains in the ages of Holocene glacier fluctuations in the Southern Hemisphere, especially South America. Here we report on latest Pleistocene and Holocene glacier fluctuations at the southern end of the Andes north and west of Ushuaia, Argentina. Surface exposure ages (10Be) from glaciated bedrock beyond cirque moraines indicate that alpine areas were free of ice by ca 16.9 ka. One, and in some cases two, closely spaced moraines extend up to 2 km beyond Little Ice Age moraines within many of the cirques in the region. The mean age of five 10Be ages from two pre-Little Ice Age moraines is 14.27–12.67 ka, whereas a minimum limiting radiocarbon age for a smaller, recessional moraine in one cirque is 12.38–12.01 ka. Our ages imply that, following glacier retreat beginning about 18.52–17.17 ka, cirque glaciers first advanced during the Antarctic Cold Reversal (14.5–12.9 ka) and may have later advanced or stabilized in the Younger Dryas Chronozone (12.9–11.7 ka). Based on the distribution of thick, geochemically distinct, and well-dated Hudson tephra, no Holocene moraines appear to be older than 7.96–7.34 ka. At some sites, there is evidence for one or more advances of glaciers sometime between 7.96–7.34 ka and 5.29–5.05 ka to limits only tens of meters beyond Little Ice Age maximum positions. Taken together, the data: 1) do not support the summer insolation hypothesis to explain Holocene glacier fluctuations in southernmost Patagonia; 2) confirm paleobotanical evidence for a warm, dry early Holocene; and 3) suggest that some glaciers in the region reached extents comparable to those of the Little Ice Age shortly before 5.29–5.05 ka. [Copyright &y& Elsevier]

Abstract: This study investigates glacier dynamic and climatic variations in the southeastern part of the Russian Altai (SE Altai) during the last 7000 years. Recent glacier retreats and ice melting in moraines has led to exhumation of organic material allowing the possibility of radiocarbon dating. We report here 57 new radiocarbon dates from wood remains buried by moraines and from proglacial forefields, from peat layers and lacustrine sediments that cover moraines, from dead trees at the upper tree limit, and from rock glaciers on trough slopes from six glacial valleys in the North Chuya Range, SE Altai. Such a numerous dataset for the vast but unified in neotectonic and climatic conditions area is presented for the first time the history of research in the Altai. Together with 62 previously published radiocarbon ages, mainly of fossil soils and peat layers in the foot of the ranges in SE Altai, they form the basis for understanding the relative magnitudes and timing of the most important glacial and climatic events of SE Altai. New data refute the traditional concept of the Russian Altai Holocene glaciations as a consecutive retreat of the late Würm glaciers and argue their complete degradation at the head of trough valleys at least 7000 cal. years BP. Moraine complexes of three Holocene glacial stages are morphologically expressed in trough valleys of the North Chuya range. They correlate with three identified periods of glacial advances: from 4900 to 4200 cal. years BP (Akkem stage), from 2300 to 1700 cal. years BP (Historical stage) and in the 13th–19th centuries (Little Ice Age (LIA) or Aktru stage). The coincident extremes of lowering temperature and increasing precipitation during the Akkem stage led to abrupt glacier advances and forming of the most remote moraine complexes downstream in the valleys. Following glacier advances had distinctly smaller magnitudes. In addition to the radiocarbon data, the time limits of the Historical stage were defined more precisely using dendrochronological and archaeological data from Scythian burials of Pazyryk culture in SE Altai. Repeated forest regrowth in the presently glaciatiated area indicates significant retreat or even complete glacier degradation during interstage warming. The decreases of glacier length in the following stages argues for intensification of aridity in the SE Altai during the second half of the Holocene. The thermal minimum in the middle of 19th century, the greatest in the last millennium, did not positively influence the mass balance of glaciers, which also supports this conclusion. [Copyright &y& Elsevier]

Abstract: Lateral moraines are prominent features of glaciated landscapes in high-mountain environments and key landforms in glacier and palaeoclimatic reconstructions, yet, compared to smaller moraines, they have been little studied and several aspects are not well understood. We here present detailed sedimentological results from the lateral moraines of Findelengletscher in SW Switzerland to gain new insights into the formation of these landforms. The lateral moraines studied here stand up to 140 m above the valley floor, are over 3 km long and strongly asymmetrical in cross-profile, with distal slopes between 29 and 36° and proximal slopes that are commonly 41–64°, but locally reach angles of up to 80°. Recorded lithofacies comprise loose clast and matrix-supported, stratified diamicts and intercalated sorted sediments in the distal slopes and near the crestline; overconsolidated matrix-supported, massive and weakly stratified diamicts and streaked-out sorted sediment lenses in the core and proximal slopes; and partly intercalated dark-brown layers overlain by loose and consolidated diamicts exposed in near-vertical walls in the proximal flank. These are interpreted as supraglacial debris flow units with intercalated fluvial ‘wash’ horizons; glaciotectonised and subglacial traction till with boudinaged and streaked-out sediment lenses; and palaeosoils overlain by sediment produced by overtopping of the former moraine surface during a subsequent advance of the glacier. Clast shape analysis and process observations reveal that the dominant mode of transport is subglacial and glaciofluvial, and that the main mode of sediment delivery to the moraines is by debris flows after the material has been transferred from the bed via englacial debris bands and meltout at the surface. This differs from previous studies that found that a supraglacial source was dominant. Sedimentary structures, clast fabric and process observations during the 1979/1980 readvance of Findelengletscher strongly suggest that proximal layers of reworked pre-existing sediments and/or basal traction zone till have been plastered onto the moraine core in several locations, causing a high degree of overconsolidation and strongly-clustered fabric eigenvalues (S1 ≤ 0.94) with clustering parallel to the moraine crestline. This suggests that a combination of basal-lateral drag and lateral plastering produces the observed proximal stability and ensures a high preservation potential. We develop a conceptual model that describes Alpine lateral moraines as structurally complex landforms that do not just record a single event as often surmised, and we discuss implications for palaeo-glacier reconstruction and the application of numerical dating methods. [Copyright &y& Elsevier]

Abstract: A multidisciplinary study including sedimentological, mineral magnetic, and palaeobotanical techniques applied to a sediment core recovered from proglacial Lake Barrancs in the seismically active Maladeta Massif has provided the basis for documenting environmental changes and palaeoseismic activity in the Central Pyrenees for the last ca. 3700 yr. Lake Barrancs is located downstream of the Tempestats and Barrancs cirque glaciers and sedimentation is dominated by clastic input corresponding to seasonal changes in sediment supply. Slow fine particle settling during the winter and sediment-loaded homopycnal flows during the warm season, triggered by snow-melting and glacier outwash, have resulted in deposition of rhythmites composed of clays, silts, and sands. The predominance of finer-grained sediments and the low concentration of relatively finer magnetite grains suggest that glacier activity was very small, if not absent, before ca. A.D. 350. Their replacement by coarser-grained sediments and the overall increased (but highly oscillating) concentrations of relatively coarser magnetite grains in the uppermost 4.3 m of the record suggest the onset of glacial activity and enhanced snow-melting in the catchment of Lake Barrancs after A.D. 350. We suggest that this onset of glacial and enhanced snow-melt activity was driven by a complex balance between winter precipitation and annual mean temperatures, among other climatic variables. Peat layers suggest two dramatic lake-level drops at A.D. 300 and A.D. 450, when Lake Barrancs was drained. The mechanisms for such extreme hydrological events are not clear. Changes in the precipitation/evaporation ratio cannot account for such desiccation events. Dam failure is unlikely since there are no geomorphological evidence of breaching processes. Geomorphological and structural evidence demonstrates active faulting since formation of Lake Barrancs and reactivation during earthquake shaking. Based on this, we propose an alternative explanation for the desiccation events that involves the draining of the lake through pre-existing fractures opened by earthquakes. Further studies in Lake Barrancs and other lakes from the Maladeta massif are necessary to validate the hypotheses presented here concerning the response of glacial and snow-melt activity to climate variability and the palaeoseismic record of the Central Pyrenees. [Copyright &y& Elsevier]

Abstract: Current knowledge about late Holocene glacier fluctuations in the south Patagonian Andes is mainly based on evidence from large outlet glaciers of the North and South Patagonian Icefields, and few data exist for the smaller glaciers elsewhere in the region. Here we provide dendrogeomorphological evidence for Little Ice Age (LIA) and post-LIA activity for five small glaciers near the northeast margin of the South Patagonian Icefield. The study sites include Glaciar Torre and Piedras Blancas in the Monte Fitz Roy area, and three adjacent glaciers near Lago del Desierto. At these sites the LIA maximum position was identified by massive moraines with mature trees dating to the late 1500s–early 1600s. Several older moraines were observed beyond these limits but could not be precisely dated. Relatively synchronous advances occurred at most glaciers in the early 1700s and were dated using living trees and in situ, subfossil material. All glaciers show three to five subsequent advances mostly concentrated between the mid-19th and early 20th centuries. Estimates based on Landsat TM imagery indicate these glaciers lost between 15 and 46% of their LIA areas by 1984 and a further 5–18% by 2005, with the smallest glaciers showing the greatest proportional loss. Paired comparisons of contemporary and the earliest known photography for the glaciers in the Fitz Roy area confirm this mass loss. These results provide important new information on the glacier history of this area but additional, more precisely-dated records are needed from many more sites before we can fully elucidate the complex late Holocene glacial history of this region. [Copyright &y& Elsevier]

Abstract: This paper documents the occurrence of the Little Ice Age (LIA) in the El Azufre and El Peñón glaciers at 35°S and in the Las Choicas and Las Damas glaciers at 34°55′S in the headwaters of the Rio Grande basin in the Central Andes of Argentina. Moraine morphology, stratigraphic relationships, radiocarbon ages obtained from peat on these glacial deposits and the proximity to the active glaciers enabled us to reconstruct the LIA advance in this area. The LIA maximum advance occurred between cal. yr 1550 and 1720 AD, and a readvance occurred around cal. yr 1830 AD. In addition, glacier fluctuations of the Las Vacas and Güssfeltd glaciers (33°S) and El Peñón and El Azufre glaciers were documented from the end of the 19th century to the present based on historical and aerial photographs, and satellite images. The glaciers showed a marked retreat during 1894–2007. Minor readvances occurred in the 1980s and 1990s, which could be related with strong warm ENSO events during these decades. Our results are consistent with observations made by other authors in the region. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to document the evolution of glaciers in the tropical Andes (between 10°N and 16°S) for the last millennium, based on moraines dated by lichenometry and radiocarbon, lake sediment records and historical documents. Viewed collectively, several glacial advances occurred synchronously. The first advance is dated around AD 1200–1350. The maximum glacial extent (MGE), defined as the furthest down-valley extent recorded synchronously by the majority of glaciers, occurred around 1630–1680 in Bolivia and Peru (the outer tropics) and around AD 1730 in Ecuador, Colombia and Venezuela (the inner tropics). Subsequently, during the 18th and 19th centuries, glaciers retreated continuously with only minor synchronous readvances. In the outer tropics, minor glacial advances occurred around 1730, 1760, 1800, 1850, and 1870. In the inner tropics, synchronous minor advances occurred around 1760, 1820 and 1880. Between the MGE and the early 20th century, glaciers lost about 30% of their total length. The retreat was slow between the 17th and 18th centuries but then became more marked. Use of the accumulation area ratio (AAR) method or historical observations in the different cordilleras revealed an increase in the equilibrium line altitude (ELA) of about 300 m from the MGE onward. Palaeoclimatic hypotheses, based on glaciological models run in different countries, suggest a cool and humid period in the 16–18th centuries followed by a colder and drier period in the 19th century. The reduction of glaciers observed from the middle of the 19th century is due to increasingly warmer conditions than before. Here, quantitative estimates are proposed to explain the evolution of the glaciers. In Venezuela, results indicate for the period 1250–1820 that mean air temperatures were 3.2±1.4 °C cooler and precipitation was about 22% higher than at present. In Ecuador, temperatures of between 0.8° and 1.1 °C lower than today, and between 25% and 35% higher accumulation than today, appear to have occurred in the 18th century, followed by a short drier but colder period at the beginning of the 19th century. In Bolivia, the MGE could be a consequence of a decrease in temperature of 1.1 to 1.2 °C, and a 20 to 30% increase in accumulation or an increase in cloudiness of about 1–2/10. We discuss not only external climatic forcing but also the coincidence between glacier expansion and a decrease in solar irradiance. Dating uncertainties, however, have made the role of volcanism in glacier fluctuations impossible to determine. Finally, we discuss the relationships between ENSO and glacier fluctuations in recent centuries, which do not match directly with current knowledge of modern teleconnections between tropical Pacific SSTs and variations in glacier mass balance. [Copyright &y& Elsevier]

Abstract: A new lichen dating method and new moraine observations enabled us to improve the chronology of glacier advances in the Cordillera Blanca (Peru) during the Little Ice Age (LIA). Our results reveal that an early LIA glacial advance occurred around AD 1330±29. However, a second major glacial advance at the beginning of the 17th century overlapped the earlier stage for most glaciers. Hence, this second glacial stage, dated from AD 1630±27, is considered as the LIA maximum glacial advance in the Cordillera Blanca. During the 17th–18th centuries, at least three glacial advances were recorded synchronously for the different glaciers (AD 1670±24, 1730±21, and 1760±19). The moraines corresponding to the two first stages are close to the one in 1630 suggesting a slow recession of about 18% in the total length of the glacier. From the LIA maximum extent to the beginning of the 20th century, the 24 glaciers have retreated a distance of about 1000 m, corresponding to a reduction of 30% in their length. This rate is comparable to that observed during the 20th century. Estimates of palaeo-Equilibrium Line Altitudes show an increase in altitude of about 100 m from the LIA maximum glacial extension at the beginning of the 17th century to the beginning of the 20th century. Because long time series are not available for precipitation and temperature, this glacial retreat is difficult to explain by past climate changes. However, there is a fair correspondence between changes in glacier length and the δ 18O recorded in the Quelccaya ice core at a century timescale. Our current knowledge of tropical glaciers and isotope variations leads us to suggest that this common tropical signal reflects a change from a wet LIA to the drier conditions of today. Finally, a remarkable synchronicity is observed with glacial variations in Bolivia, suggesting a common regional climatic pattern during the LIA. [Copyright &y& Elsevier]

Abstract: We established a chronology of monsoonal temperate glacier fluctuations in China during the last two millennia based on radiocarbon ages of fossil wood buried in moraines, lichen-dated moraines and tree ring evidence. The chronology includes data from 16 glaciers in the southeastern Tibetan Plateau including the Hengduan Mountains, the central and eastern parts of the Himalaya Mountains, and the eastern Nyainqentanglha Range. Three main periods of glacier advances are identified: around 200–600 AD, 800–1150 AD, and 1400–1920 AD. The glacier advance at about 400–600 AD was the most widespread advance in the southeastern Tibetan Plateau. Basically synchronous glacier advances occurred in the southern Himalayan Mountains during 380–600 AD, 870–1100 AD, 1400–1430 AD and 1550–1850 AD. The glacier advance around 1000 AD also occurred in the central Himalayas. Temperatures in the southeastern Tibetan Plateau calculated from Equilibrium Line Altitude (ELA) depression were 1.0 °C, 0.7 °C, 0.4 °C and 0.1 °C lower than at present (1989 AD) during the periods of 200–600 AD, 800–1150 AD, 1400–1650 AD, and the 19th century, respectively. On a centennial timescale, temperature changes rather than precipitation changes caused by variations of the south Asian summer monsoon are the controlling factor for glacier fluctuations. The widespread glacier advance during the 19th century was probably partly attributable to the result of increased winter snowfall in the central Himalayas. [Copyright &y& Elsevier]

Abstract: European Alpine glaciers are sensitive indicators of past climate and are thus valuable sources of climate history. Unfortunately, direct determinations of glacier changes (length variations and mass changes) did not start with increasing accuracy until just before the end of the 19th century. Therefore, historical and physical methods have to be used to reconstruct glacier variability for preceeding time periods. The Lower Grindelwald Glacier, Switzerland, and the Mer de Glace, France, are examples of well-documented Alpine glaciers with a wealth of different historical sources (e.g. drawings, paintings, prints, photographs, maps) that allow reconstruction of glacier length variations for the last 400–500 years. In this paper, we compare the length fluctuations of both glaciers for the 19th century until the present. During the 19th century a majority of Alpine glaciers – including the Lower Grindelwald Glacier and the Mer de Glace – have been affected by impressive glacier advances. The first maximum extent around 1820 has been documented by drawings from the artist Samuel Birmann, and the second maximum extent around 1855 is shown by photographs of the Bisson Brothers. These pictorial sources are among the best documents of the two glaciers for the 19th century. In addition to an analysis of historical sources of the 19th century, we also study the sensitivity of the Lower Grindelwald Glacier to climate parameters (multiproxy reconstructions of seasonal temperature and precipitation) for an advance and a retreat period in the 19th century using a new neural network approach. The advance towards 1820 was presumably driven by low summer temperatures and high autumn precipitation. The 1860–1880 retreat period was mainly forced by high temperatures. Finally, this nonlinear statistical approach is a new contribution to the various investigations of the complex climate–glacier system. [Copyright &y& Elsevier]

Abstract: Atmospheric temperatures measured at the Chilean Lake District (38°–42°S) showed contrasting trends during the second half of the 20th century. The surface cooling detected at several meteorological stations ranged from −0.014 to −0.021 °C a−1, whilst upper troposphere (850–300 gpm) records at radiosonde of Puerto Montt (41°26′S/73°07′W) revealed warming between 0.019 and 0.031 °C a−1. Regional rainfall data collected from 1961 to 2000 showed the overall decrease with a maximum rate of −15 mm a−2 at Valdivia st. (39°38′S/73°05′W). These ongoing climatic changes, especially the precipitation reduction, seem to be related to El Niño–Southern Oscillation (ENSO) phenomena which has been more frequent after 1976. Glaciers within the Chilean Lake District have significantly retreated during recent decades, in an apparent out-of-phase response to the regional surface cooling. Moreover, very little is known about upper troposphere changes and how they can enhance the glacier responses. In order to analyse their behaviour in the context of the observed climate changes, Casa Pangue glacier (41°08′S/71°52′W) has been selected and studied by comparing Digital Elevation Models (DEMs) computed at three different dates throughout the last four decades. This approach allowed the determination of ice elevation changes between 1961 and 1998, yielding a mean thinning rate of −2.3±0.6 m a−1. Strikingly, when ice thinning is computed for the period between 1981 and 1998, the resulting rate is 50% higher (−3.6±0.6 m a−1). This enhanced trend and the related area loss and frontal retreat suggests that Casa Pangue might currently be suffering negative mass balances in response to the upper troposphere warming and decreased precipitation of the last 25–30 yr, as well as debris cover would not prevent the glacier from a fast reaction to climate forcing. Most of recent glaciological studies regarding Andean glaciers have concentrated on low altitude changes, namely frontal variations, however, in order to better understand the regional glacier changes, new data are necessary, especially from the accumulation areas. [Copyright &y& Elsevier]

Abstract: The evolution of high-altitude glaciers and human activities in the Grandes Rousses massif is documented by high-resolution seismic reflection profiling and multiproxy analysis of short sediment cores in proglacial Lake Blanc Huez. These lacustrine data are compared with historical chronicles, geomorphological features and glaciological studies in this region of the western Alps and they allow the documentation of recent environmental changes. The specific geometry of high-amplitude reflections in the uppermost seismic unit, the lithology of short cores and the available limnological data in the lake suggest that clastic particles eroded by the glaciers and transported in suspension by glacial melt waters in early summer essentially develop homopycnal flood events in the lake. A conceptual model linking fluctuations of glacier equilibrium line altitudes in the catchment area with sedimentary facies retrieved in the lake basin is proposed. This approach allows reconstructing continuous glacier fluctuations since AD1820–1850 and suggests several phases of glacier fluctuations during the Little Ice Age (LIA). These reconstructions are based on changes in lacustrine sediment laminations, density, magnetic susceptibility, reflectance spectra, organic matter and Arsenic content. The age-depth model of short sediment cores is provided by 210Pb, 137Cs and 241Am radionuclide dating. This chronology is further supported by identifying in lacustrine sediments the impact of (i) the nearby M 5.3 Corrençon earthquake in AD 1962, (ii) the development of the ski resort at high-altitude close to the lake and (iii) the last advance of glaciers during the LIA in AD1820–1850 and the following phase of glacier retreat observed in the alpine region at the end of the LIA in AD 1880. Frequent sandy layers enriched in organic matter and associated with fluctuations in the Arsenic concentrations may result from hydraulic remobilisation of Middle Age mine tailings at the lake shore by snow melt or heavy rain fall events during the LIA. [Copyright &y& Elsevier]

Abstract: This study uses the database from national glacier inventories in the European Alps and the Southern Alps of New Zealand (hereinafter called the New Zealand Alps), which contain for the time of the mid-1970s a total of 5154 and 3132 perennial surface ice bodies, covering 2909 km2 and 1139 km2 respectively, and applies to the mid-1970s. Only 1763 (35%) for the European Alps and 702 (22%) for the New Zealand Alps, of these are ice bodies larger than 0.2 km2, covering 2533 km2 (88%) and 979 km2 (86%) of the total surface area, respectively containing useful information on surface area, total length, and maximum and minimum altitude. A parameterisation scheme using these four variables to estimate specific mean mass balance and glacier volumes in the mid-1970s and in the ‘1850 extent’ applied to the samples with surface areas greater than 0.2 km2, yielded a total volume of 126 km3 for the European Alps and 67 km3 for the Southern Alps of New Zealand. The calculated area change since the ‘1850 extent’ is −49% for the New Zealand Alps and −35% for the European Alps, with a corresponding volume loss of −61% and −48%, respectively. From cumulative measured length change data an average mass balance for the investigated period could be determined at −0.33 m water equivalent (we) per year for the European Alps and −1.25 m we for the ‘wet’ and −0.54 m we per year for the ‘dry’ glaciers of the New Zealand Alps. However, there is some uncertainty in several unknown factors, such as the values used in the parameterisation scheme of mass balance gradients, which, in New Zealand vary between 5 and 25 mm m−1. [Copyright &y& Elsevier]

Abstract: Elucidating the timing and extent of former glacier fluctuations is important because of the palaeoclimatic inferences that can be drawn from such studies. Here we present new geomorphological evidence of the patterns of glacier behaviour around the North Patagonian Icefield during the Holocene. Mapping is based on visual interpretation of Landsat 7 ETM+ and Terra ASTER satellite images, including the contemporary glaciers, areas of ice-scoured bedrock, trimlines, glacial lineations, terminal moraines, sandur and fluvial sediments, deltas and ice-contact deposits and alluvial fans. Recession of the icefield is marked by three distinct moraine sets. These moraine sets are interpreted as marking terminal positions related to the “Little Ice Age” and two preceding, but as yet undated, phases of Holocene glacier expansion. Large arcuate terminal moraines in front of three of the western glaciers are interpreted as composite features, reflecting topographic limits to glacier expansion, indicating that caution is required in the interpretation of previous 14C dates obtained from these moraines. There are strong contrasts in the patterns of glacier behaviour between the east and west sides of the North Patagonian Icefield, which cannot be attributed simply to an east/west differential in the rates of change of atmospheric temperature and precipitation. We argue here that glacier response to first-order climate forcing is tempered by second-order controls introduced by regional-scale topographic effects, notably glacier drainage basin extent and area, topographic controls on glacier snout morphology and differences in terminal environment (calving/non-calving) during glacier recession. [Copyright &y& Elsevier]

This paper presents the evidence for Late Pleistocene and Holocene palaeoclimate and glacier fluctuations of the two major icefields in Patagonia, the Hielo Patagónico Norte (47°00′S, 73°39′W) and the Hielo Patagónico Sur (between 48°50′S and 51°30′S). The palaeoenvironmental evidence suggests that glaciers still covered large areas of Patagonia at approximately 14,600 14C years BP. Uniform and rapid warming took place after 13,000 14C years BP, with no unequivocal evidence for climate fluctuations equivalent to those of the Northern Hemisphere Younger Dryas cooling event (the Younger Dryas Chronozone, dated to 11,000–10,000 14C years BP (12,700–11,500 cal. years BP). During the early Holocene (10,000–5000 14C years BP) atmospheric temperatures east of the Andes were about 2 °C above modern values in the period 8500–6500 14C years BP. The period between 6000 and 3600 14C years BP appears to have been colder and wetter than present, followed by an arid phase from 3600 to 3000 14C years BP. From 3000 14C years BP to the present, there is evidence of a cold phase, with relatively high precipitation. West of the Andes, the available evidence points to periods of drier than present conditions between 9400–6300 and 2400–1600 14C years BP. Holocene glacier advances in Patagonia began around 5000 14C years BP, coincident with a strong climatic cooling around this time (the Neoglacial interval). Glacier advances can be assigned to one of three time periods following a ‘Mercer-type’ chronology, or one of four time periods following an ‘Aniya-type’ chronology. The ‘Mercer-type’ chronology has glacier advances 4700–4200 14C years BP; 2700–2000 14C years BP and during the Little Ice Age. The ‘Aniya-type’ chronology has glacier advances at 3600 14C years BP, 2300 14C years BP, 1600–1400 14C years BP and during the Little Ice Age. These chronologies are best regarded as broad regional trends, since there are also dated examples of glacier advances outside these time periods. Possible explanations for the observed patterns of glacier fluctuations in Patagonia include changes related to the internal characteristics of the icefields, changes in the extent of Antarctic sea-ice cover, atmospheric/oceanic coupling-induced climate variability, systematic changes in synoptic conditions and short-term variations in atmospheric temperature and precipitation. [Copyright &y& Elsevier]

Glacier mass changes are considered to represent natural key variables with respect to strategies for early detection of enhanced greenhouse effects on climate. The main problem, however, with interpreting worldwide glacier mass balance evolution concerns the question of representativity. One important key to deal with such uncertainties and to assess the spatio-temporal representativity of the few available measurements is the long-term change in cumulative glacier length. The mean specific mass balance determined from glacier length change data since 1900 shows considerable regional variability but centers around a mean value of about −0.25 m year−1 water equivalent. [Copyright &y& Elsevier]

Cosmogenic exposure dating is one of the most widely used methods to constrain the deglaciation history of former glaciated areas. In Greenland, more than 1000 cosmogenic 10Be exposure ages (10Be ages) have been published within the last two decades. However, a recurring problem is that many of these studies have reported variable amounts of nuclide inheritance making the 10Be ages too old and difficult to assess without large datasets or independent age control. In this study, we test the accuracy of 10Be dating of Holocene moraines using independent age constraints from threshold lake records. In Kangerlussuaq, West Greenland, the 10Be ages of the Ørkendalen moraine system are highly clustered with a mean age of 6.8 ± 0.3 ka (no outliers). In contrast, the nearby Little Ice Age (LIA) moraine yields scattered 10Be ages ranging from 2.5 to 0.1 ka but with a mean of 0.18 ± 0.06 ka after excluding outliers which coincides with independent age constraints from threshold lakes and boulder kill dates. At Gletscherlukket, Southeast Greenland, the 10Be ages of the LIA moraine range from 10.2 to 1.6 ka with a mean of 1.9 ± 0.2 ka after excluding outliers. This is ~1.7 ka older than recorded in the proglacial threshold lakes and suggests that all samples from this site contain a significant amount of nuclide inheritance. Our results are consistent with other reports of skewed 10Be age distributions in LIA re-advance moraines and it probably reflects nuclide inheritance from exposure during the Holocene Thermal Maximum when the glaciers in Greenland were inside the LIA extent. In contrast, there is no evidence of nuclide inheritance in the Ørkendalen moraines, most likely because the glacial erosion was more intense prior to the formation of the moraines i.e. sometime between the advance phase during Last Glacial Maximum position and the subsequent lateglacial and Holocene deglaciation. Our results highlight a potential pitfall related to dating re-advance moraines using cosmogenic exposure dating and we recommend using a multi-method dating approach. [ABSTRACT FROM AUTHOR]

The Columbia Icefield is the largest icefield in the Canadian Rockies and feeds eight major glaciers that drain to three different oceans. Previous glacier studies have focused on Athabasca and Saskatchewan Glaciers, primarily due to their easy access. This paper reviews evidence of the Holocene history from all eight glaciers. Maximum Holocene glacier extent was during the Little Ice Age (LIA) with dating based mainly on minimum tree-ring estimates from trees growing on the moraines or from trees scarred, tilted or killed by the glaciers. The LIA maximum advance was during the 19th century at Athabasca (1843/4), Dome (1846), Saskatchewan (1862) and Castleguard (<1858) Glaciers but during the 18th century at Manitoba (1740), Columbia (<1739), Kitchener (<1713) and Stutfield (1758). Advances in 1714 (Athabasca) and 1740 (Saskatchewan) were of almost equal extent to the 19th century maxima. Early LIA advances are identified from a buried in-situ stump at Stutfield (>1271) and detrital wood from lateral moraines at Columbia (ca. 0.8-0.7ka). Two overridden stumps at Columbia Glacier indicate a previously unidentified advance ca 1500 A.D. These four phases of LIA coincide with major reductions in summer temperatures reconstructed at the Icefield. There are also undated (pre-1600, possibly pre LIA) moraines at Kitchener Glacier. Less extensive Neoglacial glacier events are documented by an in-situ forest bed buried by the Saskatchewan Glacier (ca 2.90–3.4 ka., equivalent to the "Peyto advance") and stumps buried by till ca. 4.2ka at Boundary Glacier. Detrital wood recovered from till at Columbia Glacier indicates at least one glacier advance ca 2.0-2.2ka. Till exposed between the Bridge River and Mazama tephras at Stutfield Glacier includes detrital wood dating 2.22–2.70 ka that possibly indicates a glacier advance immediately prior to the Bridge River tephra. Regional paleoenvironmental data indicate warmer conditions and higher treelines in the early Holocene. Detrital wood washed out of Dome and Athabasca Glaciers indicates trees were present in these valleys ca 6, 7 and 9ka upvalley of present glacier snouts. Evidence from Castleguard cave indicates upstream entrances below the present Icefield were probably ice free ca 9.5ka indicating the icefield was much reduced in extent at that time. The detrital wood may represent wood killed and reworked by limited glacier advances from the Icefield, far upstream of present glacier fronts, at these times. • Reviews and updates evidence of Holocene glacier history for eight glaciers draining from the Columbia Icefield. • Results based on field mapping, tree-ring and radiocarbon dating. • Identifies four Little Ice Age phases including new evidence for a possible advance ca 1500 AD • Confirms Neoglacial advances at ca 3000 and 4200 ka plus advances before (ca. 2.0–2.2ka) and after ca 2.5 ka. • Discusses detrital evidence of possible limited glacier events ca. 6, 7 and 9ka. [ABSTRACT FROM AUTHOR]

Investigation of Holocene extents of mountain glaciers along with the related naturally-driven climate conditions helps improve our understanding of glacier sensitivity to ongoing climate change. Here, we present the first Holocene glacial chronology in the Mont-Blanc massif (Argentière glacier) in the French Alps, based on 25 in situ -produced cosmogenic 10Be dates of moraines and glacial bedrocks. The obtained ages from mapped sequences of moraines at three locations reveal that the glacier retreated from its Lateglacial extent and oscillated several times between ∼11.7 ka and ∼10.4 ka, i.e. during the Younger Dryas/Early Holocene (YD/EH) transition, before substantially retreating at ∼10.4 ka. Climate conditions corresponding to the past extents of Argentière glacier during the YD/EH transition (∼11 ka) and the Little Ice Age (LIA) were modelled with two different approaches: by determining summer temperature differences from reconstructed ELA-rises and by using a Positive Degree Day (PDD) mass-balance model. The ELA-rise reconstructions yield a possible range of temperatures for the YD/EH transition that were lower by between 3.0 and 4.8 °C compared to the year 2008, depending on the choice of the ELA sensitivity to temperature. The results from the PDD model indicate temperatures lower by ∼3.6–5.5 °C during the YD/EH transition than during the 1979–2002 period. For the LIA, our findings highlight the role of local precipitation changes, superimposed on the dominant temperature signal, in the detailed evolution of the glacier. Overall, this study highlights the challenge that remains in accurately inferring paleoclimate conditions from past glacier extents. • Argentière glacier oscillated 5 times between 11.7 ka and 10.5 ka. • Modeled Early Holocene temperature range is 3.6–5.5 °C below modern values. • Local precipitation changes explain detailed Little Ice Age glacier fluctuations. [ABSTRACT FROM AUTHOR]