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Déclin des deux plus grands glaciers des Alpes françaises au cours du XXIe siècle : Argentière et Mer de Glace
Abstract and Figures
Des modélisations ont été réalisées sur les deux plus grands glaciers des Alpes françaises afin d’estimer leur évolution au cours du XXI esiècle.Pour un scénario climatique intermédiaire avec réduction des émissions de gaz à effet de serreavant la fin du XXI esiècle (RCP 4.5), les simulations indiquent que le glacier d’Argentière devrait disparaître vers la fin du XXI esiècleet que la surface de la Mer de Glace pourrait diminuer de 80 %. Dans l’hypothèse la plus pessimiste d’une croissance ininterrompue des émissions de gaz à effet de serre (RCP 8.5), la Mer de Glace pourrait disparaître avant 2100 et le glacier d’Argentière une vingtaine d’années plus tôt.
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... The Mer de Glace is melting rapidly. Its thickness has decreased by 32 % since the beginning of the 20 th century (Vincent et al., 2019). Since 1860, the length has decreased by 1.5 km. ...
Appendix 1 for "Visitors’ motivations to engage in glacier tourism in the European Alps: comparison of six sites in France, Switzerland, and Austria"
-> https://doi.org/10.1080/09669582.2022.2044833
Climate change is causing profound changes in high mountain environments, including the rapid retreat of glaciers. The retreat and potential disappearance of Alpine glaciers during the twenty-first century raises questions about the future of glacier tourism sites. This perspective article reflects on these changes with a desk-based approach to suggest three possible ways glacier tourism can adapt to anticipated glacier loss. These three strategies include further developing geotourism, transforming last-chance tourism into “dark tourism,” and using virtual reality to “virtually” reconstruct disappearing glaciers. This paper draws on three cases to discuss the potential of these strategies. The first is the Aletsch Glacier, the largest in the Alps, which is listed as a UNESCO World Heritage Site. It has also been the subject of recent work on geotourism. The second case is Mer de Glace, the largest glacier at the Montenvers site in France. This glacier has been studied in the context of last-chance tourism. The final case is the Mortaretsch Glacier in Switzerland, which can be reached from Diavolezza and has not been the subject of many studies. However, this site is one of the first to incorporate virtual reality technology into the tourist experience of the glacier.
The Infierno Glacier is located in Aragon (Spain), Pyrenees Mountain range, the only one in this country that still preserves white glaciers. These are the southernmost glaciers in Europe and are currently in rapid decline. The work analyzes the evolution of the glacier between 2016 and 2022 and provides data, for this period, which lacked this information, in an area bordering the glacial ice survival. In addition to the observations on the glacier itself, the variables (precipitation, temperature, snow volume and thickness) that allow an understanding of this evolution are studied. The results show a setback of the glacier (thickness losses: 4.6 m; front retreat; 14.9 m). The evolution has frequent trend changes, linked to the interannual climatic irregularity characteristic of the Pyrenees. The main explanatory factor is the thermal increase. The thermal anomalies with respect to the average reference values have increased, in this period, by +0.55 °C. The year 2022 has been particularly warm and has recorded the greatest losses for this glacier. With respect to precipitation, it has an irregular behavior and shows a tendency to decrease (−9% in the same period). This work has the additional interest of analyzing a glacier in the terminal phase, which if current trends continue, evolves into dead ice.
The Infierno glacier is located in Aragon (Spain), Pyrenees mountain range, southern slope, the only one in this country that still preserves white glaciers. These are the southernmost glaciers in Europe and are currently in rapid regression. The work analyzes the evolution of the glacier between 2016 and 2022 (taking as "year zero" or starting point, 2015). In addition to the observations on the glacier itself, the variables (precipitation, temperatures, snow volumes and thicknesses) that allow understanding this evolution are studied. The results offer strong regression, with thickness losses in that period of 4.6 m and retreat of its front of 14.9 m. The evolution has frequent trend changes, linked to the interannual climatic irregularity characteristic of this mountain range. The main explanatory factor is the thermal increase. The thermal anomalies with respect to the average reference values have increased, in this period, +0.55° C. The year 2022 has been particularly warm and has recorded the greatest regression of the glacier (between May and August, the thermal anomalies were between +4° C and +2° C). Regarding precipitations, they have irregular tendencies and show a decreasing trend (-9% in the same period of time).
After being perceived negatively by the inhabitants of mountain areas, glaciers have been promoted as a tourist attraction for over two centuries. The first visits to the Arveyron Arch (Chamonix) in the 18th century were followed by cog railways and cable cars that allow access to the largest glaciers in the Alps and in the world in just a few dozen minutes. Thus, glacier tourism today includes practices and touristic sites that are emblematic of certain mountain territories. However, rising temperatures and the extremely rapid glacier retreat also make these glacier sites markers of climate change. The Mer de Glace in France, the Rhone glacier in Switzerland and the Pasterze glacier in Austria are among the major glacier tourist sites that are experiencing the full force of landscape changes linked to the retreat of the cryosphere. What do these changes imply for the operators of these glacier tourism sites? And for their visitors? Using mixed methodologies, this PhD thesis attempts to answer these two questions for six major Alpine glacier tourism sites. In essence, the results show that glacial tourism sites are largely impacted by climate change and the glaciological and geomorphological changes it brings to mountain territories. These impacts lead to difficulties in site management, itinerary issues, difficulties in carrying out certain activities which may become more dangerous, or a decrease in the attractiveness of the sites through less attractive glacial activities or through a "landscape degradation" feared by the site managers. However, our results with visitors to the sites show that this "degradation" of the landscape does not drastically reduce visitors' satisfaction with the glacial landscape: the negative judgements are limited to glaciers or paraglacial forms, but only slightly affect visitors' general appreciation of the landscape. At the same time, a new form of tourism - last chance tourism - is developing around glaciers and shows that they are now considered as "endangered species". Furthermore, the site managers in question are implementing strategies for adapting to climate change that are mainly reactive and which raise the question of their long-term sustainability. This question is even more important as glacier modelling for the year 2050 suggests that current adaptations will not be sufficient.
Les régions de montagne concentrent des caractéristiques qui rendent les effets du changement climatique particulièrement visibles. Elles constituent ainsi des sentinelles du changement en cours et à venir. Elles disposent d’atouts naturels et socio-économiques qui les distinguent d’autres zones géographiques, notamment sur le plan des ressources en eau, de la biodiversité et du patrimoine agricole et culturel. L’environnement spécifique de haute montagne est le support d’activités emblématiques de loisirs et de tourisme. Les régions de montagne sont également le siège de nombreux aléas naturels gravitaires qui complexifient et renchérissent leur développement socio-économique. Le changement climatique agit sur la quasi-totalité de ces enjeux interconnectés, en modifie les caractéristiques et ébranle les modes de gestion traditionnels des atouts et difficultés intrinsèques des régions de montagne. Connaissances interdisciplinaires et outils se développent pour pouvoir tenir compte de ces enjeux dans leurs stratégies territoriales de développement.
Depuis la mise en tourisme des « glacières » de Chamonix en 1741, les paysages glaciaires contribuent fortement à l’attractivité des territoires alpins, et donc à leur économie. Le recul généralisé des glaciers lié au changement climatique en cours engendre de profonds changements paysagers qui impactent de nombreux sites touristiques de l’arc alpin. Le travail doctoral proposé sur l’avenir des activités touristiques liées aux paysages englacés, novateur et pluridisciplinaire, s’empare d’une question sensible pour les acteurs du tourisme et de l’aménagement en montagne. Il se propose d’y répondre : 1.en établissant une typologie des sites touristiques en contexte glaciaire, qui intègre sur la longue durée leur développement et la dynamique des glaciers correspondants, 2.en étudiant l’évolution interannuelle de leur fréquentation depuis les années 1980, caractérisées par la dernière avancée glaciaire alpine, 3.en explicitant les représentations et attentes du public au moyen d’enquêtes accompagnées d’une approche photographique, 4.en proposant une approche méthodologique applicable à plusieurs échéances à partir d’une analyse critique des aménagements passés et actuels. L’étude sera prioritairement conduite à l’échelle des Alpes occidentales, éventuellement étendue aux Alpes centrales et orientales, afin de permettre une dimension comparative. Les résultats enrichiront les connaissances actuelles sur les conséquences économiques du changement climatique en montagne. Ils contribueront à fonder les prises de décisions des gestionnaires d’infrastructures (refuges, téléphériques, buvettes) et des décideurs locaux (communes, communautés de communes, syndicats) et régionaux quant à l’évolution des produits touristiques proposés en contexte glaciaire.
Natural attractions constitute the most important supply sources of world tourism. Seas, streams, lakes, valleys, forests, etc. besides attractions like and glaciers are among the prominent sources in tourism. Mountainous areas and snow, which are the key to the winter season, are a valid tourism activity. In summer, it is an important activity for mountainous regions glacial tourism. However, this type of tourism has not been sufficiently researched yet (Salim et al., 2021a). Tourism research in glaciated areas is quite common. Although it is a new phenomenon, in the last 10 years many glaciers around the world have become popular turned into touristic attractions (Welling et al., 2015). Especially, A steady growth in global tourism demand means that cryospheric tourism is more glacial tourism, mountainous countries started to be seen as an important tourism project in the regions (Wang and Zhou, 2019). Glaciers; glacial valleys, moraines, eskers and aretes etc. it forms the basis of many impressive landscape types such as characterized by highly dynamic appearances that usually attract tourists (Welling et al., 2015). Glacial tourism; glacier trekking, excursion by vehicle (train, tracked car, etc.), skiing, climbing, photography, scientific research and education activities (Wang and Zhou, 2019; Wang et al., 2020). Glacial tourism in many countries such as Canada, Switzerland, France, China, New Zealand, Norway, Iceland successfully carried out as an important activity and regional economic benefits (Wang et al., 2020). However, in the Holocene (11.7 ka-present) the problem of climate change leads to the retreat of glaciers, this situation also creates a separate discussion area on the sustainability of tourism activity. Although it is a new trend, glacial tourism is in the international literature is making progress on various issues. However, no scientific study has been found in Turkey that refers to the concept of 'glacial tourism'. Turkey's current current glacial areas and topographies with traces of glaciers. In this context, in the current research, the introduction of the concept of glacial tourism, academic to create an awareness in the sense of intended to be revealed. In this sense, the conceptual framework of glacial tourism is adaptation and sustainability to climate change with examples from the world general issues such as the current literature are discussed by evaluating.
Due To the effects of climate change, tourist locations such as glacial landscapes are increasingly becoming last-chance tourism (LCT) destinations. LCT is paradoxical: although visitors to such locations possess high environmental awareness, their travel generates greenhouse gas emissions that threaten these destinations. However, visiting LCT destinations and observing glacial landscapes threatened by climate change may positively affect pro-environmental behaviour. This article aims to explore how experiencing receding glaciers can influence intentions to adopt pro-environmental behaviour. A quantitative survey of 284 visitors to a major glacier tourism site in France (Montenvers-mer-de-Glace) was caried out to test the influence of landscape, emotions, satisfaction, and LCT-related motivations on intentions to adopt pro-environmental behaviours. The results show that landscapes perceived as symbolic of climate change, LCT motivations, and overall satisfaction positively influenced pro-environmental behaviour intentions. To further encourage such intentions, stakeholders should promote practices based on education and experience.
The largest collection so far of glaciological and geodetic observations suggests that glaciers contributed about 27 millimetres to sea-level rise from 1961 to 2016, at rates of ice loss that could see the disappearance of many glaciers this century.
In north-western Tibet (34.0° N, 82.2° E) near
lake Aru Co, the entire ablation areas of two glaciers (Aru-1 and Aru-2)
suddenly collapsed on 17 July and 21 September 2016. The
masses transformed into ice avalanches with volumes of 68 and 83×106 m3 and ran out up to 7 km in horizontal distance, killing nine
people. The only similar event currently documented is the 130×106 m3 Kolka Glacier rock and ice avalanche of 2002 (Caucasus
Mountains). Using climatic reanalysis, remote sensing, and three-dimensional
thermo-mechanical modelling, we reconstructed the Aru glaciers'
thermal regimes, thicknesses, velocities, basal shear stresses, and ice
damage prior to the collapse in detail. Thereby, we highlight the potential of using
emergence velocities to constrain basal friction in mountain glacier models.
We show that the frictional change leading to the Aru collapses occurred in
the temperate areas of the polythermal glaciers and is not related to a
rapid thawing of cold-based ice. The two glaciers experienced a similar
stress transfer from predominant basal drag towards predominant lateral
shearing in the detachment areas and during the 5–6 years before the
collapses. A high-friction patch is found under the Aru-2 glacier tongue,
but not under the Aru-1 glacier. This difference led to disparate behaviour
of both glaciers, making the development of the instability more visible for
the Aru-1 glacier through enhanced crevassing and terminus advance over a
longer period. In comparison, these signs were observable only over a few
days to weeks (crevasses) or were absent (advance) for the Aru-2 glacier. Field
investigations reveal that those two glaciers were underlain by soft, highly
erodible, and fine-grained sedimentary lithologies. We propose that the specific
bedrock lithology played a key role in the two Tibet and the Caucasus
Mountains giant glacier collapses documented to date by producing low bed
roughness and large amounts of till, rich in clay and silt with a low friction
angle. The twin 2016 Aru collapses would thus have been driven by a failing
basal substrate linked to increasing pore water pressure in the subglacial
drainage system in response to increases in surface melting and rain
during the 5–6 years preceding the collapse dates.
Glacier thickness distribution is a prerequisite to simulate the future of glaciers. Inaccurate thicknesses may lead to significant uncertainties in the timing of future changes to glaciers and their consequences for water resources or sea level rise. Unfortunately, glacier thickness distribution is rarely measured and consequently has to be estimated.
In this study, we present an approach developed on the well documented Argentière Glacier (French Alps) that uses surface mass balance (SMB) together with surface flow velocity data to quantify glacier thickness distribution over the entire surface of the glacier.
We compare the results of our approach to those obtained applying Farinotti et al. (2009) approach. Our results show that glacier thickness distribution are significantly biased when the glacier SMB profile used to quantify the ice fluxes is not constrained with in situ measurements. We also show that even with SMB measurements available on the studied glacier, ice flux estimates can be inaccurate. This inability to correctly estimate ice fluxes from the apparent SMB may be due to the steady state assumption that is not respected from the available glacier surface topography data. Therefore, ice thickness measurements on few cross sections (four are used in this study) are required to constrain the ice flux estimates and lead to an overall agreement between the ice thickness estimations and measurements. Using our approach, the ice thicknesses only differ by 10% from observations in average, but can differ by up to 150m (or 30%) locally. We also show that approaches that use the glacier surface slope can lead to large uncertainties given that the quantification of the slope is highly uncertain. The approach presented here does not pretend to be applied globally but rather as a tool to quantify ice thickness distribution over the entire surface of glaciers for which a few in situ surface mass balance and thickness data are available together with surface flow velocities that can be obtained for example from remote sensing.
This study focuses on simulations of the seasonal and annual surface
mass balance (SMB) of Saint-Sorlin Glacier (French Alps) for the
period 1996–2015 using the detailed SURFEX/ISBA-Crocus snowpack
model. The model is forced by SAFRAN meteorological reanalysis data,
adjusted with automatic weather station (AWS) measurements to ensure that simulations of all the energy balance components, in particular turbulent fluxes, are accurately represented with respect to the measured energy
balance. Results indicate good model performance for the simulation
of summer SMB when using meteorological forcing adjusted with
in situ measurements. Model performance however strongly decreases
without in situ meteorological measurements. The sensitivity of the
model to meteorological forcing indicates a strong sensitivity to
wind speed, higher than the sensitivity to ice albedo. Compared to
an empirical approach, the model exhibited better performance for
simulations of snow and firn melting in the accumulation area and
similar performance in the ablation area when forced with
meteorological data adjusted with nearby AWS measurements. When such
measurements were not available close to the glacier, the empirical
model performed better. Our results suggest that simulations of the
evolution of future mass balance using an energy balance model
require very accurate meteorological data. Given the uncertainties in the temporal evolution of the relevant meteorological variables and glacier
surface properties in the future, empirical approaches based on
temperature and precipitation could be more appropriate for
simulations of glaciers in the future.
This article investigates the climatic response of a series of indicators for characterizing annual snow conditions and corresponding meteorological drivers at 1500 m altitude in the Chartreuse mountain range in the Northern French Alps. Past and future changes were computed based on reanalysis and observations from 1958 to 2016, and using CMIP5–EURO-CORDEX GCM–RCM pairs spanning historical (1950–2005) and RCP2.6 (4), RCP4.5 and RCP8.5 (13 each) future scenarios (2006–2100). The adjusted climate model runs were used to drive the multiphysics ensemble configuration of the detailed snowpack model Crocus. Uncertainty arising from physical modeling of snow accounts for 20 % typically, although the multiphysics is likely to have a much smaller impact on trends. Ensembles of climate projections are rather similar until the middle of the 21st century, and all show a continuation of the ongoing reduction in average snow conditions, and sustained interannual variability. The impact of the RCPs becomes significant for the second half of the 21st century, with overall stable conditions with RCP2.6, and continued degradation of snow conditions for RCP4.5 and 8.5, the latter leading to more frequent ephemeral snow conditions. Changes in local meteorological and snow conditions show significant correlation with global temperature changes. Global temperature levels 1.5 and 2 °C above preindustrial levels correspond to a 25 and 32 % reduction, respectively, of winter mean snow depth with respect to the reference period 1986–2005. Larger reduction rates are expected for global temperature levels exceeding 2 °C. The method can address other geographical areas and sectorial indicators, in the field of water resources, mountain tourism or natural hazards.
Worldwide glacier retreat and associated future runoff changes raise major concerns over the sustainability of global water resources, but global-scale assessments of glacier decline and the resulting hydrological consequences are scarce. Here we compute global glacier runoff changes for 56 large-scale glacierized drainage basins to 2100 and analyse the glacial impact on streamflow. In roughly half of the investigated basins, the modelled annual glacier runoff continues to rise until a maximum (‘peak water’) is reached, beyond which runoff steadily declines. In the remaining basins, this tipping point has already been passed. Peak water occurs later in basins with larger glaciers and higher ice-cover fractions. Typically, future glacier runoff increases in early summer but decreases in late summer. Although most of the 56 basins have less than 2% ice coverage, by 2100 one-third of them might experience runoff decreases greater than 10% due to glacier mass loss in at least one month of the melt season, with the largest reductions in central Asia and the Andes. We conclude that, even in large-scale basins with minimal ice-cover fraction, the downstream hydrological effects of continued glacier wastage can be substantial, but the magnitudes vary greatly among basins and throughout the melt season.
Recent record-breaking glacier melt values are attributable to peculiar extreme events and long-term warming trends that shift averages upwards. Analyzing one of the world's longest mass-balance series with extreme value statistics, we show that detrending melt anomalies makes it possible to disentangle these effects, leading to a fairer evaluation of the return period of melt extreme values such as 2003, and to characterize them by a more realistic bounded behavior. Using surface energy balance simulations, we show that three independent drivers control melt: global radiation, latent heat and the amount of snow at the beginning of the melting season. Extremes are governed by large deviations in global radiation combined with sensible heat. Long-term trends are driven by the lengthening of melt duration due to earlier and longer-lasting melting of ice along with melt intensification caused by trends in long-wave irradiance and latent heat due to higher air moisture.
Basal slip accounts for a large part of the flow of ice streams draining ice from Antarctica and Greenland into the ocean. Therefore, an appropriate representation of basal slip in ice flow models is a prerequisite for accurate sea level rise projections. Various friction laws have been proposed to describe basal slip in models. Here, we compare the influence on grounding line (GL) dynamics of four friction laws: the traditional Weertman law and three effective pressure-dependent laws, namely the Schoof, Tsai and Budd laws. It turns out that, even when they are tuned to a common initial reference state, the Weertman, Budd and Schoof laws lead to thoroughly different steady-state positions, although the Schoof and Tsai laws lead to much the same result. In particular, under certain circumstances, it is possible to obtain a steady GL located on a reverse slope area using the Weertman law. Furthermore, the predicted transient evolution of the GL as well as the projected contributions to sea level rise over a 100-year time horizon vary significantly depending on the friction law. We conclude on the importance of choosing an appropriate law for reliable sea level rise projections and emphasise the need for a coupling between ice flow models and physically based subglacial hydrological models.
The quantification of uncertainty sources in ensembles of climate projections obtained from combinations of different scenarios and climate and impact models is a key issue in climate impact studies. The small size of the ensembles of simulation chains and their incomplete sampling of scenario and climate model combinations makes the analysis difficult. In the popular single-time ANOVA approach for instance, a precise estimate of internal variability requires multiple members for each simulation chain (e.g., each emission scenario-climate model combination), but multiple members are typically available for a few chains only. In most ensembles also, a precise partition of model uncertainty components is not possible because the matrix of available scenario/models combinations is incomplete (i.e., projections are missing for many scenario-model combinations). The method we present here, based on data augmentation and Bayesian techniques, overcomes such limitations and makes the statistical analysis possible for single-member and incomplete ensembles. It provides unbiased estimates of climate change responses of all simulation chains and of all uncertainty variables. It additionally propagates uncertainty due to missing information in the estimates. This approach is illustrated for projections of regional precipitation and temperature for four mountain massifs in France. It is applicable for any kind of ensemble of climate projections, including those produced from ad hoc impact models.
Transverse profiles and velocities which have been measured on the ablation zone of Mer de Glace more or less continuously since 1891 contradict the Weertman–Nye theory of glacier kinematic waves. Faint broad waves, which undoubtedly result from fluctuations in the balance, travel down the glacier faster than this theory predicts. (This theory having first been completed by taking changes in width with time and with distance down the glacier into account.) On the other hand, velocity fluctuations are synchronous and more or less the same over the entire length studied (6 km).
These discrepancies result from bottom friction being of the solid type, i.e. independent of sliding velocity. Friction should also be almost insensitive to discharge in subglacial waterways, since in the steady state energy for keeping them open, not entirely flooded, and at atmospheric pressure, is superabundant. The sliding velocities at all cross-profiles are thus controlled by some areas where the body of the glacier suffers strong deformation because the valley shape is far from cylindrical. One such controlling zone exists on Mer de Glace owing to the existence of a subglacial transverse shoulder. A new perturbation equation and a new rough expression for wave velocity are given.
Intervals between Forbes’ bands were plotted on seven aerial surveys between 1939 and 1979. Progressive tilting of the slices of blue, dusty ice from the position from which these dark bands proceed and progressive lowering of their exposed edge must be taken into account. This analysis confirms the validity of our simple model for velocity fluctuations and allows us to estimate the entire series since the year 1888.