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15 pages; International audience; 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 10 Be dates of moraines and glacial bedrocks. The obtained ages from mapped sequences of moraines at three locations reveal that the glacier was retreating from its Lateglacial extent and oscillating 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 coupled with a dynamic ice flow model. The ELArise reconstructions yield a possible range of summer temperatures for the YD/EH transition that were cooler by between 3.0 and 4.8°C compared to the year 2008, depending on the choice of the ELA sensitivity to summer temperature. The results from the PDD model indicate temperatures cooler by ~3.6 to 5.5°C during the YD/EH transition than during the 1979-2002 period. For the LIA, our findings highlight that the role of local precipitation changes, superimposed on the dominant temperature signal, is important in the detailed evolution of the glacier. Overall, this study highlights the challenge that remains in accurately inferring paleoclimate conditions from past glacier extents.

The Magallanes&ndash, Tierra del Fuego region, Southern Patagonia (53&ndash, 56&deg, S) features a plethora of fjords and remote and isolated islands, and hosts several thousand glaciers. The number of investigated glaciers with respect to the multiple Neoglacial advances is based on a few individual studies and is still fragmentary, which complicates the interpretation of the glacial dynamics in the southernmost part of America. Schiaparelli Glacier (54&deg, 24&prime, S, 70&deg, 50&prime, W), located at the western side of the Cordillera Darwin, was selected for tree-ring-based and radiocarbon dating of the glacial deposits. One focus of the study was to address to the potential dating uncertainties that arise by the use of Nothofagus spp. as a pioneer species. A robust analysis of the age&ndash, height relationship, missing the pith of the tree (pith offset), and site-specific ecesis time revealed a total uncertainty value of &plusmn, 59 years. Three adjacent terminal moraines were identified, which increasingly tapered towards the glacier, with oldest deposition dates of 1749 &plusmn, 5 CE, 1789 &plusmn, 5 CE, and 1867 &plusmn, 5 CE. Radiocarbon dates of trunks incorporated within the terminal moraine system indicate at least three phases of cumulative glacial activity within the last 2300 years that coincide with the Neoglacial phases of the Southern Patagonian Icefield and adjacent mountain glaciers. The sub-recent trunks revealed the first evidence of a Neoglacial advance between ~600 BCE and 100 CE, which so far has not been substantiated in the Magallanes&ndash, Tierra del Fuego region.

The study on the migrations of the confluence between the rivers Po and Dora Baltea was based on a detailed observation of aerial photographs, field surveys and sediment stratigraphy. The age of the sediments and morphological features was based on radiocarbon datings, on the presence of archaeological settlements and ancient artefacts and on historical data. The aerial photographs of the GAI 1954 flight of the Italian Air Force were used because in the year 1954, some low terraces were still clearly visible, while today are almost completely obliterated because of the works for the improvement of the rice fields. A succession of nine fluvioglacial and fluvial terraces and many abandoned riverbeds have been identified: the interpretation of the morphological features made it possible to identify the Po and Dora Baltea evolution during the late Holocene. The study established that during the last 3000 years, the confluence of the Dora Baltea into the Po has constantly migrated to the west and that this migration occurred during alluvial phases dating back to the Iron Age, 2nd century BC–1st century AD, 5th century AD, 6th–8th century AD and 15th–19th century AD. The alluvial phases occurred during periods of increased floods in northern Italy and advances of the Alpine glaciers in northwestern Italy and Switzerland. Neither tectonic deformations nor anthropic actions seem to have influenced fluvial evolution in the last 3000 years. The westward migration of the confluence between the rivers was therefore triggered by climatic changes, but caused by the different responses of the catchments of the Dora Baltea and the Po rivers to climatic changes, and by the greater slope of the Dora Baltea flood plain.

To improve our knowledge of glacier area changes in the central Chilean and Argentinean Andes (32°9′S–33°4′S), two new glacier inventories from 1989 to 2013/14 are compared with a reinterpreted inventory from 1955. Comparisons show glacier area retreat of 30 ± 3% since 1955, decreasing from 134 to 94 km2 in 2013/14, whilst the annual rate of area loss showed a small increase (insignificant) between the periods of 1955–1989 and 1989–2013/14. Separate analysis of the 1989 and 2013/14 inventories, including a larger sample, revealed a higher rate of glacier change compared with the smaller samples of these inventories. Additionally, an analysis at ~5 year intervals for six major glaciers (1955–2013) indicates large variability in response times and area loss magnitudes. Glacier Olivares Alfa, for example, lost 63% of its ice area, while the Juncal Norte Glacier lost only 10% (1955–2013). The findings from this study improve our current knowledge base concerning widespread glacier decline in the southern Andes, and furthers monitoring efforts in this poorly described region of the world, a region containing vital water resources for populated areas in South America.

International audience; 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 36Cl surface exposure ages obtained from five sites at Kerguelen to document the glacial history. The 36Cl 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.

Using instrumental archives, aerial photographs, satellite images, old maps, descriptions of early explorers and old photographs we identified and mapped nine front positions of the Ullukam Glacier (SW slope of Elbrus) for the period from the end of XIX to the early XXI centuries. In 1884–2009 glacier retreated by 775 m. It advanced from 1971 to 1987 (36 m). The glacier fluctuations in the previous period were reconstructed using geomorphologic data, lichenometry, modern and buried soil description and radiorarbon analyses. We identified three Little Ice Age moraines of almost equal magnitude when the Ullukam Glacier was 889 m longer than in 2009. Two later advances occurred in the first third to middle of XIX century and in 1870s The recent fluctuations of the Ullukam Glacier closely correspond to the retreat two other glaciers in Elbus area. The location of the buried soil in the valley of Ullukam glacier brings evidence that the glacier have not advanced lower than 2813 m a.s.l. at least during the last four thousand years.

In this study, a linear model computing the air temperature fluctuations from the measured glacier snout fluctuations has been applied, for the first time, to three small glaciers in the western Tauern Alps (eastern Alps) in the period 1929–2011. The considered glaciers, with areas between 0.2 and $$1.3\,\hbox {km}^2$$ , are characterized by relevant time variations of their morphology, length and slope. The model requires the knowledge of two parameters: the glacier climate sensitivity $$C_s$$ and the glacier response time $$\tau$$ , both depending on the glacier morphological characteristics and on the precipitation. Applied to the glaciers assuming $$C_s$$ and $$\tau$$ as in the original formulation, it underestimates the temperature increase of $${\approx } 1.8\,^{\circ }\hbox {C}$$ derived over the whole period from the in situ data. Given the characteristics of these small glaciers, these parameters have been recalibrated by means of a non-linear least-square regression using an independent set of glaciers. Their mean value is of about 210 m/K and 3.8 years respectively. With the recalibrated values of the new glacier climate sensitivity $$C^*_s$$ and response time $$\tau ^*$$ , the temperature fluctuations derived by the model reproduce well those obtained from the observed temperatures computed over the hydrological year, with linear correlations between 0.8 and 0.9. The increase of the modeled mean temperature over the whole period fits in with that derived from observed temperature. Considering that the length fluctuations of these small glaciers affect significantly their slope and length, we tested the impact in the model of a time dependent formulation of $$C_s$$ and $$\tau$$ : the results indicate slight improvements both in the values of the correlation between the reconstructed and the observed temperature fluctuations and in the global temperature increase. Given the above value of climate sensitivity, the large retreat of the small alpine glaciers threatens their survival within a few decades, but the morphological changes in progress may counteract the glacier disappearance.

International audience; 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 the region, experimented 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-Antartic regions. To investigate the deglaciation pattern since the Last Glacial Maximum (LGM) period, we present the first 13 cosmogenic 36Cl surface exposure ages from four sites in the Kerguelen Islands. The 36Cl ages from erratic and moraine boulders span from 24.4±2.7 ka to 0.3±0.1 ka. We combined these ages with extisting 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 Antartic Cold Reversal (ACR) period (-14.5-12.9 ka), during which the Bontemps moraine was formed by the advance of a CIC outlet glacier. Deglacication continued during the Holocene probably until 3 ka with evidence of miror advances during the last millennium. This chronology is in pace with majeor changes in the ᵟ18O in a recent West Antartica ice core record, showing that Kerguelen Islands glaciers are particularly sensitive and relevant to document climate change in the southern polar regions.

Fedchenko glacier is by far the largest glacier in the Pamir, Tajikistan. Owing to early accurate mapping of the glacier it is possible to evaluate glacier changes over eight decades, which is an exceptionally long time period for this remote mountain region. During this time a total volume loss of 5 km3 was observed on the main trunk of the glacier, while the total area changed by only 1.4%. It is observed that the volume loss migrates from the lower parts of the glacier towards the upper ablation zone. The comparatively small change in area is a result of the supraglacial debris cover on the glacier tongue, which decouples the area loss from the volume loss to a considerable degree. The observed velocities of the glacier do not reflect the volume changes up to now because the interannual variability is larger than possible long-term changes so far. The intra-annual velocity distribution in the central ablation zone probably reflects the evolution of the basal drainage system. Based on ice thickness measurements and simple ice-dynamic assumptions, the total volume of Fedchenko glacier is 123.4 ± 8 km3.

In this study, contour lines from the topographic maps at a 1:100,000 scale (mapped in 1968), Landsat MSS/TM/OLI images, ASTER images and SPOT 6-7 stereo image pairs were used to study changes in glacier length, area and surface elevation. We summarized the results using the following three conclusions: (1) During the period from 1973 to 2013, glaciers retreated by 412 &plusmn, 32 m at a mean retraction rate of 10.3 &plusmn, 0.8 m&middot, year&minus, 1 and the relative retreat was 5.6 &plusmn, 0.4%. The glacier area shrank by 7.5 &plusmn, 3.4%, which was larger than the glacier length. In the periods of 1968&ndash, 2000, 2000&ndash, 2005 and 2000&ndash, 2013, the glacier surface elevation change rates were &minus, 7.7 &plusmn, 1.4 m (&minus, 0.24 &plusmn, 0.04 m&middot, 1), &minus, 1.9 &plusmn, 1.5 m (&minus, 0.38 &plusmn, 0.25 m&middot, 1) and &minus, 5.0 &plusmn, 0.11 m&middot, 1), respectively. The changes in the glacier area and thickness exhibited similar trends, both showing a significant increasing reduction after 2000. (2) Eleven glaciers were identified as surging glaciers. Changes of the mass balance in surging glaciers were stronger than in non-surging glaciers between 1968 and 2013. Changes of area in surging glaciers were weaker than in non-surging glaciers. (3) Increasing temperature was the major cause of glacier thickness reduction and area shrinkage. The increase in precipitation, to a certain extent, inhibited glacial ablation but it did not change the status of the shrinkage in the glacial area and the reduction in the glacier thickness.

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 Allerod and the Younger Dryas in the Alps.

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 Be-10 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 similar to 7 kyr at the latest. The re-evaluation of 21 moraine Be-10 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 Allerod and the Younger Dryas in the Alps.

Despite being a key location for paleoglaciological research in north-central Asia, with the largest number of modern and Pleistocene glaciers, and in the transition zone between the humid Russian Altai and dry Gobi Altai, little is known about the precise extent and timing of Holocene and late Pleistocene glaciations in western Mongolia. Here we present detailed information on the distribution of modern and late Holocene glaciers, and new results addressing the geomorphological differentiation and numerical dating (by optically stimulated luminescence, OSL) of Pleistocene glacial sequences in these areas. For the Mongolian Altai, geochronological results suggest large ice advances correlative to marine isotope stages (MIS) 4 and 2. This is in contrast to results from the Khangai mountains, central Mongolia, showing that significant ice advances additionally occurred during MIS3. During the Pleistocene, glacial equilibrium-line altitudes (ELAs) were ~500 to >1000m lower in the more humid portion of the Russian and western Mongolian Altai, compared to 300-600 m in the drier ranges of the eastern Mongolian Altai. Pleistocene ELAs in the Khangai mountains were depressed by 700-1000 m, suggesting more humid conditions at times of major glaciation than in the eastern Mongolian Altai. This paleo-ELA pattern reveals that the precipitation gradient from the drier to the more humid regions was more pronounced during glacial times than at present.

11 páginas, 5 figuras, 2 tablas., 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., This research was supported by projects AMB93-0814-C02-01 and PB96-0815, and by a MEC Ramón y Cajal contract (JCL).

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 in, 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 attitude 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 delta O-18 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.

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (∼42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (∼5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable. Fil: Zemp, Michael. Universitat Zurich; Suiza Fil: Frey, Holger. Universitat Zurich; Suiza Fil: Gärtner-Roer, Isabelle. Universitat Zurich; Suiza Fil: Nussbaumer, Samuel U.. Universitat Zurich; Suiza Fil: Hoelzle, Martin. Universite de Fribourg; Suiza. Universitat Zurich; Suiza Fil: Paul, Frank. Universitat Zurich; Suiza Fil: Haeberli, Wilfried. Universitat Zurich; Suiza Fil: Denzinger, Florian. Universitat Zurich; Suiza Fil: Ahlstrøm, Andreas P.. Geological Survey Of Denmark And Greenland; Dinamarca Fil: Anderson, Brian. Victoria University Of Wellington; Nueva Zelanda Fil: Bajracharya, Samjwal. International Centre For Integrated Mountain Development; Nepal Fil: Baroni, Carlo. Università degli Studi di Pisa; Italia Fil: Braun, Ludwig N.. Bavarian Academy Of Sciences; Alemania Fil: Càceres, Bolívar E.. Instituto Nacional de Meteorología E Hidrología; Ecuador Fil: Casassa, Gino. Universidad de Magallanes; Chile Fil: Cobos, Guillermo. Universidad Politécnica de Valencia; España Fil: Dàvila, Luzmila R.. Unidad de Glaciología y Recursos Hídricos; Perú Fil: Delgado Granados, Hugo. Universidad Nacional Autónoma de México; México Fil: Demuth, Michael N.. Natural Resources Canada; Canadá Fil: Espizua, Lydia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Fischer, Andrea. Osterreichische Akademie Der Wissenschaften; Austria Fil: Fujita, Koji. Nagoya University; Japón Fil: Gadek, Bogdan. University Of Silesia; Polonia Fil: Ghazanfar, Ali. Global Change Impact Studies Centre; Pakistán Fil: Hagen, Jon Ove. University of Oslo; Noruega Fil: Holmlund, Per. Stockholms Universitet; Suecia Fil: Karimi, Neamat. Ministry of Energy; Irán Fil: Li, Zhongqin. Chinese Academy of Sciences; República de China Fil: Pelto, Mauri. Nichols College; Estados Unidos Fil: Pitte, Pedro Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Popovnin, Victor V.. Moscow State University; Rusia Fil: Portocarrero, Cesar A.. Unidad de Glaciología y Recursos Hídricos; Perú Fil: Prinz, Rainer. Universidad de Innsbruck; Austria Fil: Sangewar, Chandrashekhar V.. Geological Survey of India; India Fil: Severskiy, Igor. Institute Of Geography; Kazajistán Fil: Sigurdsson, Oddur. Icelandic Meteorological Offic; Islandia Fil: Soruco, Alvaro. Universidad Mayor de San Andrés; Bolivia Fil: Usubaliev, Ryskul. Central Asian Institute For Applied Geosciences; Kirguistán Fil: Vincent, Christian. Laboratory of Glaciology and Environmental Geophysics; Francia

Most glaciological studies in Argentina have focused on the large outlet glaciers of the Southern Patagonia Icefield (SPI); the numerous smaller neighboring glaciers have received significantly less attention. We present an inventory of 248 medium- to small-size glaciers (0.01-25 km2) adjacent to the northeast margin of the SPI, describe their change over the period 1979-2005 and assess local and regional climatic variations in an attempt to explain the observed glacier changes. Based on an ASTER mosaic from 20 February 2005 and the ASTER Global Digital Elevation Model, we identified a total glacier area of 187.2 ±7.4 km2 between 600 and 2870ma.s.l. Glaciers are largely debris-free and are concentrated in the western, more humid sector adjacent to the SPI. Using a 20 March 1979 US military intelligence Hexagon KH-9 satellite photograph, we measured a total areal reduction of ∼33.7 km2 (15.2%) between 1979 and 2005. Ablation season temperatures from the study area have followed a regional warming trend that could partly explain the observed glacier shrinkage. Annual precipitation estimates show a gradual decrease between 1979 and 2002 that may also have contributed to the ice mass loss. Fil: Masiokas, Mariano Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Delgado, Silvia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Pitte, Pedro Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Berthier, E.. Université de Toulouse; Francia Fil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Skvarca, P.. Museo del Hielo Patagónico. Glaciarium; Argentina Fil: Ruiz, Lucas Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Ukita, J.. Niigata University. Faculty of Science; Japón Fil: Yamanokuchi, T.. Remote Sensing Technology Center of Japan; Japón Fil: Tadono, T.. Earth Observation Research Center; Japón. Japan Aerospace Exploration Agency; Japón Fil: Marinsek, S.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina Fil: Couvreux, F.. Centre National de Rechercheres Meteorologiques; Francia Fil: Zalazar, Laura Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

Discharge from marine-terminating outlet glaciers accounts for up to half the recent mass loss from the Greenland ice sheet, yet the causal factors are not fully understood. Here we assess the factors controlling the behaviour of Humboldt Glacier (HG), allowing us to evaluate the influence of basal topography on outlet glacier response to external forcing since part of HG’s terminus occupies a large overdeepening. HG’s retreat accelerated dramatically after 1999, coinciding with summer atmospheric warming of up to 0.19°C a–1 and sea-ice decline. Retreat was an order of magnitude greater in the northern section of the terminus, underlain by a major basal trough, than in the southern section, where the bedrock is comparatively shallow. Velocity change following retreat was spatially non-uniform, potentially due to a pinning point near HG’s northern lateral margin. Consistent with observations, numerical modelling demonstrates an order-of-magnitude greater sensitivity to sea-ice buttressing and crevasse depth (used as a proxy for atmospheric warming) in the northern section. The trough extends up to 72 km inland, so it is likely to facilitate sustained retreat and ice loss from HG during the 21st century.

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (∼42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (∼5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.

Tidewater glaciers in Greenland experienced widespread retreat during the last century. Information on their behaviour prior to this is often poorly constrained due to lack of observations, while determining the drivers prior to instrumental records is also problematic. Here we present a record of the dynamics of Kangiata Nunaata Sermia (KNS), southwest Greenland, from its Little Ice Age maximum (LIAmax) to 1859 – the period before continuous air temperature observations began at Nuuk in 1866. Using glacial geomorphology, historical accounts, photographs and GIS analyses, we provide evidence KNS was at its LIAmax by 1761, had retreated by ~5 km by 1808 and a further 7 km by 1859. This predates retreat at Jakobshavn Isbræ by 43–113 years, demonstrating the asynchroneity of tidewater glacier terminus response following the LIA. We use a one-dimensional flowband model to determine the relative sensitivity of KNS to atmospheric and oceanic climate forcing. Results demonstrate that terminus forcing rather than surface mass balance drove the retreat. Modelled glacier sensitivity to submarine melt rates is also insufficient to explain the retreat observed. However, moderate increases in crevasse water depth, driving an increase in calving, are capable of causing terminus retreat of the observed magnitude and timing.

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Harter, M. Gilbert, A. Berthier, E. Six, D. Observatoire des Sciences de I'Univers de Grenoble (OSUG); Institut des Sciences de I'Univers (INSU); TOSCA program of the French Space Agency (CNES) We thank all those who have taken part in carrying out the extensive field measurements on Mer de Glace. This study has been funded by the Observatoire des Sciences de I'Univers de Grenoble (OSUG) and by the Institut des Sciences de I'Univers (INSU). All the measurements have been performed in the framework of the French 'GLACIO-CLIM (Les GLACiers comme Observatoire du CLIMat)' project. E.B. acknowledges support from the TOSCA program of the French Space Agency (CNES). We are grateful to H. Harder who revised the English. We also thank S. Adhikari, Scientific Editor, and two anonymous reviewers whose comments improved the quality of the manuscript. 0 INT GLACIOL SOC CAMBRIDGE ANN GLACIOL; Simulations of glacier evolution are needed to assess future changes in the runoff regime of mountain catchments. A simplified parameterized model is applied here to simulate future thickness changes and glacier retreat of Mer de Glace, French Alps. A normalized thickness change function describing the spatial distribution of surface-elevation changes as a function of elevation has been determined. The model reveals that under present climatic conditions Mer de Glace will continue to shrink dramatically in the coming decades, retreating by 1200 m between now and 2040. The method has certain limitations related to the uncertainties of the normalized function based on thickness change data. An error of 10% in the normalized function leads to uncertainties of 46%, 30% and 18% in Mer de Glace front, surface area and glacier-wide mass-balance changes respectively in 2040. Because the difference of the normalized function largely exceeds 10% from one glacier to another, even within a given glacier size class and elevation range, it would be very risky to extrapolate the normalized function to unmeasured glaciers. Consequently, the method is applicable only on glaciers where past surface elevation changes are well constrained.

Field observations, old terrestrial photographs and maps, aerial orthophotos and detailed geomorphological mapping were used for compiling and validating a 119‐year cumulative record of terminus ch...