# Impacts of Climate Change on Mountaineering Routes in the Écrins Massif (Western Alps, France)

Analysis based on a corpus of 70 itineraries from the guidebook Les 100 plus belles courses et randonnées (1974)

Mathis Arnaud, Jacques Mourey, Philippe Bourdeau, Richard Bonet et Ludovic Ravanel

Traducteur : Traduction révisée par Christopher Mole

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## Édition électronique

URL : https://journals.openedition.org/rga/13044

DOI : 10.4000/12a6t

ISSN : 1760-7426

## Cet article est une traduction de :

Impacts du changement climatique sur les itinéraires d'alpinisme du massif des Écrins (Alpes occidentales, France) - URL : https://journals.openedition.org/rga/13072 [fr]

## Éditeur :

UGA Éditions/Université Grenoble Alpes, Association pour la diffusion de la recherche alpine

## Référence électronique

Mathis Arnaud, Jacques Mourey, Philippe Bourdeau, Richard Bonet et Ludovic Ravanel, « Impacts of Climate Change on Mountaineering Routes in the Écrins Massif (Western Alps, France) », *Journal of Alpine Research* | *Revue de géographie alpine* [En ligne], 112-4 | 2024, mis en ligne le 08 septembre 2024, consulté le 22 novembre 2024. URL : http://journals.openedition.org/rga/13044 ; DOI : https://doi.org/10.4000/12a6t

Ce document a été généré automatiquement le 22 novembre 2024.

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Le texte seul est utilisable sous licence CC BY-NC-ND 4.0. Les autres éléments (illustrations, fichiers annexes importés) sont « Tous droits réservés », sauf mention contraire.
# Impacts of Climate Change on Mountaineering Routes in the Écrins Massif (Western Alps, France)

Analysis based on a corpus of 70 itineraries from the guidebook Les 100 plus belles courses et randonnées (1974)

Mathis Arnaud, Jacques Mourey, Philippe Bourdeau, Richard Bonet et Ludovic Ravanel

Traduction : Traduction révisée par Christopher Mole

The authors thank the guides and scientists who took the time to be interviewed, the Parc national des Écrins for funding this study, and Brad Carlson (CREA Mont-Blanc) for statistical processing of attendance data from the CampToCamp website.

## Introduction

1. The Alps are among the most sensitive regions to climate change (IPCC, 2019). The mean annual air temperature in the French Alps increased by 1.5°C to 2.1°C, depending on the massifs, between 1950 and 2014 (Einhorn et al., 2015) with a clear acceleration since the 1990s. This situation has led to significant modifications of the high mountain environments (Beniston et al., 2018; IPCC, 2019) such as glacier retreat (Shannon et al., 2019; Hock and Huss, 2021; Hugonnet et al., 2021) and degradation of rockwall permafrost (Harris et al., 2001; Etzelmüller et al., 2020; Ravanel et al., 2020; Magnin et al., 2023). Numerous geomorphological and glaciological processes result from this, impacting the practice of mountaineering (alpinism)(Ritter et al., 2011; Temme, 2015; Purdie and Kerr, 2018; Mourey et al., 2019a, 2019b, 2022), inscribed since 2019 on the Representative List of the Intangible Cultural Heritage of Humanity (Debarbieux, 2023).

2. Previous research has documented the effects of climate change on mountaineering such as Salim et al. (2019), Rushton and Rutty (2023), Hanly et al. (2023), or Salim et al. (2023). Mourey et al. (2019) highlighted the impact of climate change on 95 mountaineering routes in Mont-Blanc massif. Their study is based on the classic
guidebook "Le Massif du Mont-Blanc – Les 100 plus belles courses" (Rébuffat, 1973) written by the famous guide Gaston Rébuffat. 25 glaciological and geomorphological processes related to climate change and affecting the routes were identified. On average, each route is affected by 9 processes including glacier retreat, steeper and more frequently snow-free glaciers, the destabilization of moraines, more open crevasses and bergschrunds, increased rockfall activity in permafrost-related rockwalls, steeper ice aprons, which are more quickly bare ice, and glacier tongue retreat. These processes mean that during summer, 36% (34/95) of the routes have rarer and unpredictable optimal climbing periods, 27% (27/95) are no longer accessible, and 3% (3/95) have completely disappeared. This initial study was complemented by Mourey et al. (2022) based on the 25 processes identified in Mont-Blanc massif. The authors developed a graphical method for mapping them by adapting the UNIL legend for geomorphological maps (Schoeneich 1993; Lambiel et al., 2016). They used it on 36 routes in the Valais Alps (Switzerland). This methodology simplifies data collection and analysis through precise localization/quantification of the processes. It also facilitates knowledge dissemination to the general public.

The evolution of mountaineering routes in Écrins massif, a major destination for mountaineers, has been very poorly documented so far with only one study, that of Bourdeau (2014), showing that mountaineering is facing a change in seasonality, with more delicate conditions, and an increase in technical difficulties. This qualitative approach has highlighted the adaptive behaviors of guides and mountaineers facing increasingly variable and difficult conditions.

The present research aims to map the geomorphological and glaciological processes related to climate change affecting mountaineering routes in Écrins massif by reusing the methodology of Mourey *et al.* (2022). This work, based on the reference guidebook "Le massif des Écrins – Les 100 plus belles courses et randonnées" (Rébuffat, 1974), will evaluate the applicability of the mapping method to a massif of the southern French Alps, located a hundred kilometers south of the Mont-Blanc massif and the Valais Alps, presenting a warmer and drier climate as well as one with less ice cover (Gardent *et al.*, 2014) and different snow conditions (Beaumet *et al.*, 2021). The results obtained and the associated maps are also thought to help in promoting knowledge dissemination among professional and amateur mountaineers as well as the implementation of adaptive behaviors.

# Study Area

## Écrins Massif, a Major Destination for Mountaineers

Écrins massif is in the French administrative departments of Hautes-Alpes and Isère (Figure 1). With an area of 2,710 km², it is vast and divided into several sectors and valleys: Valgaudemar and Valbonnais to the West, Oisans and Guisane to the North, Vallouise to the East, and Champsaur and Durance to the South. This massif is situated on the crystalline axis that extends from Mercantour to Mont-Blanc; it is mainly composed of metamorphic rocks (gneiss, migmatites, and granites; Debelmas *et al.*, 1980).
<figure><img src="image_3.png" /><figcaption>Figure 1: Écrins massif</figcaption></figure>

Source: Écrins National Park.

6 In terms of climate, the southern part of Écrins massif is primarily influenced by a sub-Mediterranean climate, while the northern part is affected by oceanic and continental influences. The massif is the third most glaciated massif in France with an area of 69 km², covered by glaciers following Mont-Blanc (102km²) and Vanoise (93km²) (Gardent et al., 2014). It also corresponds to the highest number of glaciers in France (282), which lost 32% of their area between 1967 and 2009 (Gardent et al., 2014), i.e. 8% in average per decade. Rockwall permafrost is present in high-altitude rock faces above 3000-3500m (Magnin et al., 2015). Its degradation linked to climate change can lead to rockfall (Ravanel and Deline, 2011; Deline et al., 2021), such as near the Glacier Carré on La Meije (3984 m a.s.l.) in 2018.

7 La Barre des Écrins (4102 m a.s.l.) is the highest peak in the massif. The average altitude of the peaks studied here is 3620m a.s.l. The mean altitude of the huts is 2520m a.s.l. The Aigle hut (3440m a.s.l.) and the Écrins hut (3175m a.s.l.) are the only two huts in the massif whose access is via a glacier. Mountaineering in the massif is renowned for maintaining its wild and authentic character, notably due to long access routes. It offers a variety of routes suitable for both beginners and experienced climbers, thanks to a wide range of itineraries documented in Rébuffat's guidebook (1974). These routes include 'normal' and relatively easy snow routes, (e.g. route n°16: Roche Faurio normal route), technical and challenging north faces (e.g. route n°65: Col du Diable, north couloir), and mountain pass crossings combining mountaineering and hiking (e.g. route n°17: Col du Sélé traverse).
# Le massif des Écrins – Les 100 plus belles courses et randonnées as a Reference Guide

8. The guidebook "Le massif des Écrins - Les 100 plus belles courses et randonnées", first published in 1974 and reissued in 1989 and 2001, describes 139 diverse routes (rock, snow, mixed, and trails) used as the basis for this study. Considered as a reference for several decades, it is presented as a coffee table book and, like the other books in the collection, the routes are classified from 1 to 100 according to increasing difficulty. Some numbers correspond to several routes. This is particularly the case with n°11, which includes five different routes in the sector of Col du Replat (3335m a.s.l.) and these routes are accompanied by a letter (11a, 11b, 11c, etc.). Descent routes are not always described. In such cases, the most commonly used route is chosen. For example, for route n°56 (south ridge of Petit Pelvoux, 3753 m a.s.l.), we chose the descent via glacier des Violettes.

9. 70 routes, selected for their variety, popularity, and interest were studied (see Annexes 1 and 2). Routes n°1 and 2 were not analyzed as they are hiking routes. Routes n°3 to 10 were also not analyzed as they are located in neighboring massifs of Cerces and Thabor. The most visited routes (with over 20 reports on *CampToCamp* website between 1970 and 2013) were selected.

10. Among the 70 studied routes, 27 are rock (39 %), 18 are snow (26 %), and 25 are mixed routes (36 %). This classification corresponds to their nature as it was in 1974. The routes were divided into different sections: access to the refuge, access to the base of the route or to the bergschrund, the route itself, and the descent from the summit. In certain cases, such as Chaud couloir on Trois Dents du Pelvoux (3683m a.s.l.; n°90), there is no hut on the route. The route is thus divided into only three sections (approach/access, route, and descent).

## Method

### Adaptation of the Method of Mourey et al. (2022) to the Écrins Massif

11. The method adopted here is from Mourey *et al.* (2022), developed for the Valais Alps and used to map the geomorphological and glaciological processes affecting mountaineering routes. Following recent work on different types of Alpine glacial features (Kaushik *et al.*, 2022), some modifications and adaptations have been made. The term "ice-snow covers" is now replaced by "ice aprons," defined as thin ice masses (a few meters thick), with an area of less than 0.1 km², having slopes steeper than 40°, and composed of cold and stationary ice (Ravanel *et al.*, 2023).

12. A new process (see Results), 'Earlier in the season or permanent retreat of ice-snow covers' completes the legend of the maps. These covers are immobile, irregularly shaped masses of snow or ice on slopes generally below 35/40° (Kaushik et al., 2022). Here it is a question of considering a development that seems specific to Écrins massif as its southern location and its lower altitudes certainly explain this situation. The corresponding symbol is also used to map the early retreat of residual snow and the retreat of mountain ice caps, the masses of ice and snow that occupy high-altitude
peaks (Kaushik et al., 2022). Our interviews and study of maps and aerial photos do not always enable us to differentiate precisely between an ice cap and an ice-snow cover.

## From Interviews to Mapping

We conducted a series of interviews with experts of Écrins massif to identify and map the geomorphological and glaciological processes impacting the selected routes. In total, 14 semi-structured interviews were conducted with 11 interviewees. Seven are high mountain guides, and four are scientists and mountaineers. The duration of the interviews varied between two and six hours. The first series of interviews allowed us to study the changes in each of the 70 routes over nearly 50 years. Specialists described the geomorphological and glaciological evolutions of the routes, enabling the identification and mapping of associated processes. To improve this work, data from interviews were crossed with aerial images and historical or current topographic maps. The most recent IGN aerial photos used are from 2023 for the department of Hautes-Alpes and 2018 for Isère. As for historical aerial photos, the shots used are from 1948 to1953 and from 1967 to1971. Although these images cover a large part of the study area, some areas were not photographed. In such cases, the tool *remonterletemps.ign.fr* was used to study the evolution of routes between the 1980s and 2020 (Figure 2).

<figure><img src="image_4.png" /><figcaption>Figure 2: Various media from IGN used for photo-interpretation (Glacier Blanc area)</figcaption></figure>

Glacial retreat was primarily assessed through the cartographic work of Gardent *et al.* (2014), which studied the years 1967-1971 and 2018. Some glacier outlines were improved using historical aerial photos from 1979 and current ones. Based on these, an initial cartographic version of the processes affecting the routes was created using QGIS (version 3.28.4; see.: Mourey *et al.*, 2022).

A second series of interviews, generally of shorter duration, was then conducted with 6 additional experts to confirm or correct the processes previously mapped. Thus, each route was overseen by at least two different individuals.

Following this mapping, we conducted a statistical analysis of the collected data. An initial analysis was performed using Excel, which highlighted the most frequent phenomena and the most affected sections of the routes, the average number of processes affecting each route, and the average level of modification. Subsequently, we chose to perform a discriminant factorial analysis – a statistical method that helps to describe and classify predefined groups based on a series of variables, using Rstudio software – to study the relationships between the level of modification of a route and its orientation, difficulty, and nature.
17 Furthermore, the routes were classified according to the method developed by Mourey et al. (2019) into five levels of modification based on different parameters: increased technical difficulties, higher exposure to objective hazards, and changes in seasonality for optimal climbing conditions. Therefore, Level 0 corresponds to unaffected routes, and Level 1 to slightly affected routes with only a short portion affected by geomorphological or glaciological changes. These changes do not significantly increase objective hazards or technical difficulty. Level 2 corresponds to routes that are moderately affected. Optimal conditions for climbing are rarer, and there is an increase in technical difficulty and/or exposure to objective hazards during the ascent. Level 3 concerns highly affected routes that can no longer be climbed in summer. Level 4 corresponds to routes lost due to the effects of climate change.

# Results

## Impacts of Climate Change on Mountaineering Routes in the Écrins Massif

18 On average, a route is affected by nine different geomorphological or glaciological processes. The three processes affecting the greatest number of routes are: glacier retreat, steeper glaciers, and glacier surfaces which are more often bare ice. These affect 97, 91 and 91% of the routes respectively. Two rock routes have not changed (Level 0,3%): n°20b, the Dents de Coste Counier traverse (3025 m a.s.l.), and n°36, the north ridge of Aiguille Dibona (3130m a.s.l.). Thirty routes have changed a small amount (Level 1, 43%), 22 have changed moderately (Level 2, 31%), and 16 are no longer visited in summer (Level 3,23 %) (Figure 3).

<figure><img src="image_5.png" /><figcaption>Figure 3: Route locations and modification levels</figcaption></figure>
19

The average modification level is 1.74, and no routes have disappeared (Level 4). There is a direct link between the level of modification of a route and the number of processes affecting it. On average, routes with modifications of Level 1 are affected by 6 processes, 12 for Level 2, and 13 for Level 3 (Figure 4). Routes that are not impacted are affected by only one geomorphological process, namely the early summer melting of glaciers and snow covers, but according to the experts interviewed, the premature retreat of this residual snow does not have a significant impact on the routes.

20

The 10 most frequent processes (Figure 5) affect more than half of the routes studied. In other words, 51% of routes (36 out of 70) are affected by more than 10 geomorphological and glaciological processes.

<figure><img src="image_6.png" /><figcaption>Figure 5: Distribution of processes by frequency of occurrence and route sections</figcaption></figure>

<figure><img src="image_7.png" /></figure>
## Route Sections Affected in Different Ways

21 The different parts of the routes are not affected by the same processes (Figure 5) in relation to altitude. Because of their low altitude (min. altitude: 1797m a.s.l., avg.: 2518m, max: 3450m), access routes to huts are subject to few processes. Among the 22 huts studied, only four have their access routes affected. These are the highest huts whose access is still glaciated or recently deglaciated: Écrins (3175m a.s.l.), Glacier Blanc (2542m), Aigle (3450m), and Promontoire (3092m). 19% of routes (13 out of 70) have their access to the hut affected. Glacier retreat is the most common process, affecting all four routes.

22 The access from the hut to the climbing route is affected by 21 different processes, with an average of 4.4, mainly glacial processes. The most recurrent processes are glacial retreat (56 out of 70; 80%), more rapidly cleared glacier surfaces (42 out of 70; 60%), and steeper glaciers (42 out of 70; 60%).

23 The routes themselves are affected by an average of 3.3 processes. The main processes affecting them are: steeper and more rapidly "icy" ice aprons, i.e. a lack of snow on their surface (27 out of 70; 39%), shrinking ice aprons (29 out of 70; 41%), and increased frequency of rockfalls in recently deiced sectors (31 out of 70; 44%). These processes generally have a direct effect on technical difficulty and objective hazards and influence the level of route modification. The descent is the portion of the route affected by the greatest number of processes (22 out of 24; 92%), and by nine processes on average. It is mainly affected by processes linked to the melted glaciers: glacier retreat (66 out of 70; 94%), steeper glaciers and surfaces which are more often bare ice (60 out of 70; 86%), and more open crevasses (42 out of 70; 60%).

## The Most Affected Routes: Mixed Routes and Snow Couloirs

24 Mixed and snowy routes such as couloirs and goulottes, characterized by steep slopes of ice, snow or a combination of the two, have contributed to the reputation of the Écrins massif since the first half of the 20th century. At the time of the first edition of the guidebook, summer was the ideal season for these climbs. Rébuffat even indicated that the Chaud couloir at Trois Dents du Pelvoux (3683m a.s.l.) was "always in good condition". According to all the interviewees, this is no longer the case, as the couloir can only be climbed between late autumn and spring. Most of the mixed, snow and ice routes of a certain difficulty (above D meaning Difficult) are no longer passable in summer. According to the discriminant factor analysis (Figure 6), north-facing mixed and snow routes with a difficulty greater than D are the most impacted by the effects of climate change and are no longer feasible in summer. Mixed routes account for 94% of routes with a modification of Level 3. They can only be climbed between autumn and spring, and not every year. Climbers need to be opportunistic and reactive, and regularly monitor changing conditions.
<figure><img src="image_8.png" /><figcaption>Figure 6: Discriminant Factor Analysis of route modification levels in relation to function of altitude, level of difficulty, orientation and type</figcaption></figure>

This Discriminant Factor Analysis enables us to study whether the different levels of modification are linked to the nature of the route, its difficulty and orientation. The results show that the routes with the greatest impact are mixed (x/y: 0.29; 0.02) or snow (x/y: 0.18; 0.01), north-facing (x/y: 0.6; -0.32) and with a difficulty D (x/y: 0.52; -0.14).

25

The north couloir of Les Bans (n°68) is an excellent example (Figure 7). Fifty years ago, it was described as a snow and ice route, comparable to the Gervasutti couloir at Mont Blanc du Tacul (4248m a.s.l., Mont-Blanc massif). Today, in summer, the snow and ice slope has given way to a rock couloir subject to numerous rockfalls.

<figure><img src="image_9.png" /><figcaption>Figure 7: Map of the geomorphological and glaciological processes affecting the north couloir of Les Bans (n°68); 13 processes affect the route (on IGN map)</figcaption></figure>
A New Process Identified: Earlier Summer Melting of Ice-Snow Covers

<figure><img src="image_10.png" /></figure>

Earlier summer melting of ice-snow cover and ice caps affects 43 out of 70 routes (61%). It mainly affects an altitudinal belt 2900-3500m a.s.l., although other sectors may be affected. Descents (37 out of 70; 53%) and access (16 out of 70; 23%) are the most affected sections. The traverse of Mont Pelvoux (3946 m a.s.l.) via the Coolidge couloir (orientation SW, 3350-3800m a.s.l., 45° max; Figure 8) is experiencing early melting of the ice-snow cover in the couloir, leading to an increase in the frequency of rockfalls. In 2022, the couloir was no longer possible to climb by the end of June (oral communication. M. Jaudon, keeper of the Pelvoux refuge).

<figure><img src="image_11.png" /><figcaption>Figure 8: The Coolidge couloir and the various geomorphological and glaciological processes affecting it (ph.: PGHM Briançon, July 2020)</figcaption></figure>

<figure><img src="image_12.png" /></figure>

However, many descents used to be eased by these ice-snow covers, using the ramasse technique (Bourdeau, 2014) consisting of in deliberately gliding on snow while braking with an ice axe. Today, these descents have been replaced by unstable scree slopes that are often difficult and painful to navigate. This is particularly true of the descent of La Meije (3984m a.s.l.), after the passage of the Amieux ledge, where climbers were able to let themselves slide on the snow. Now, the descent through the rocks is longer and more arduous for climbers. Moreover, the mountain ice caps once present on various peaks are now sometimes replaced by fractured rock ridges, which are less attractive and less aesthetically pleasing, and present greater objective dangers. The case of Calotte des Agneaux (3634m a.s.l.) is emblematic; it lost its entire ice cap (Figure 9) in 2022.
<figure><img src="image_13.png" /><figcaption>Figure 9: Evolution of Calotte des Agneaux (3634m a.s.l.) between 1967 and 2022</figcaption></figure>

Ph. IGN.

# Discussion

## Is There a Similar Situation in the Valais Alps and the Mont-Blanc Massif?

28 The results obtained in the Écrins are very similar to those obtained for the Valais Alps and the Mont-Blanc massif. For all three massifs, a route is affected by an average of nine geomorphological and glaciological processes and the routes most affected by the effects of climate change are mixed or snow. An earlier melting of their ice-snow covers during the summer season, generally associated with an increase in the frequency of rockfalls, results in an increase in hazards and technical difficulties. A quarter of the routes surveyed in the Valais, Mont-Blanc, and Écrins massifs are no longer suitable for summer climb, and have been classified as Level 3.

## Changing the Nature of Snow Routes

29 Over the last five decades, seven routes in the Écrins massif initially considered as snow routes have seen their characteristics and nature changed. Formerly described as traversing easy cols, or constituting starting mountaineering routes, they are now mixed or rock routes. These routes have not only lost their relative accessibility for beginners, but also their technical and aesthetic interest. Today, they seem to be mostly neglected. Rébuffat's guide (1974) rated these routes as F (Easy) or PD (Not Very Difficult). Good physical condition was all that was needed for climbing, with snow present on the entire route and throughout the summer season. This was the case for the normal route to Pic de Neige Cordier (3613m a.s.l.; descent of itinerary n°13), which was visited every day in summer by guides who could supervise up to 10 clients (oral comm. C. Albrand). Today, this summit is hardly ever climbed in summer, as the hazards on the ascent to Col Emile Pic (3483m a.s.l.) and the technical difficulties are too high, and the rating has been reassessed from F to D.
30

Although the nature of these seven routes has evolved, the average number of processes affecting one of them is eight, with an average modification level of 1.3. This is slightly lower than the rest of the routes. Several factors may explain this result, including their lower difficulty, rated F to PD. Because they are not as steep also makes them less exposed to gravitational processes such as rockfalls. Similarly, most snow routes (6 out of 7; 86%) have no ice aprons, an absence which can be attributed in part to their relatively low altitude, 3462m a.s.l. on average.

31

These changes have a major impact on the activity of mountain guides. The number of mountaineering clients has been reduced due to the increase in technical and belaying difficulties. The diversity of snow itineraries is also declining. Until the early 2000s, the Écrins hut offered several starting snow routes (Roche Faurio, Pic de Neige Cordier, Pic du Glacier Blanc and Dôme des Écrins). Today, apart from the aforementioned Pic de Neige Cordier, the normal route to Pic du Glacier Blanc (3527m a.s.l.) quickly becomes rocky in summer. The Dôme des Écrins (4015m a.s.l.) is visited less and less by climbers, who consider its exposure to serac falls too high. Some sections are steeper and/or icy, as was the case in the summer of 2022, when a zone at around 3850m a.s.l. required the use of ice screws and the use of front-point cramponing. Local guide offices offer this ascent with discretion and only to clients with a good technical level, with some guides even refusing to climb it. The normal route to the Roche Faurio (3730m a.s.l.) is still the most important snow route in the basin of the Glacier Blanc, even if this itinerary worsens in summer (more open crevasses, glacier retreat, glacier cleared of snow more quickly).

## Some Positive Changes?

32

According to the experts, some routes are benefiting positively from the effects of climate change on certain sections. For example, several routes are no longer exposed to serac falls or are experiencing a reduction in the frequency of serac falls.

33

On the NE face of Coolidge Peak (3774m a.s.l.), the Bonatti route, which has a modification level of 3, was threatened by falling seracs until the 1990s. Today, the ice bar dominating the route has completely disappeared to make way for an ice apron, which nevertheless leaves the sector exposed to rockfalls. On other routes, such as the Davin couloir (n°38), or the north face of Mont Pelvoux's East pass, local guides have observed a decrease in the frequency of serac falls, making the route less exposed. The normal ascent route to Les Rouies (3589m a.s.l.; n°19) has also been positively affected. In 1974, Rébuffat noted that "the Rouies glacier overhangs the route, and serac falls are always possible". This is no longer the case today as the glacier has retreated sufficiently.

34

The melting of ice-snow cover earlier in the summer season can also have a positive effect on certain sections of routes, allowing climbers to avoid the systematic use of crampons, as in the case of the ascent and descent of the Cinéastes ridge (3203 m a.s.l.; n°37).

## An Iteration of Climatic, Cultural, Technical and Sporting Factors

35

The impact of climate change can redirect climbers towards old routes that have been abandoned as a result of advances in equipment and changes in climbing practices. For
example, this is the case for the ascent and traverse of Pelvoux (n°34), whose most
popular ascent route was the Rochers Rouges route (Devies and Laloue, 1951) until the
widespread use of front-point crampons in the 1960s-1970s, enabling the Coolidge
couloir to become the classic ascent route. With the early loss of snow cover in summer
(Figure 9), the fractured and unstable bedrock made the ascent highly vulnerable to
rockfalls, which – together with the efforts of the hut keeper in informing the public –
helped to revive the popularity of the Rochers Rouges route.

36

In the same way, snow routes are often subject to changes or even a postponement of
the ascent and to seasonality (Salim et al., 2019; Rushton et al., 2023). Once favored for
summer mountaineering, some couloirs are now used only in winter or spring,
sometimes for steep skiing, an activity that remains reserved for particularly good
skiers. Most interest in these routes is for descents (the "descension" in Cailhol, 2021)
rather than ascents. The change in seasonality is often accompanied by a change in
practice, in this case from mountaineering to ski-touring/mountaineering (Bourdeau,
2014). This is also the case for passes that used to be popular in summer as part of the
Haut-Tour des Écrins, or the Tour des Ailefroides, which no longer have the same appeal or
accessibility as they are cleared of snow earlier and earlier in the summer season. Ski
touring in spring is therefore an interesting adaptive alternative, even if some winters
with less snow also affect activity. For example, the Tour de La Meije, a classic spring
tour, was made exceedingly difficult or even impossible in 2022 and 2023 due to a lack
of snow in the Serret du Savon passage (3399 m a.s.l.).

Conclusions

37

This study focused on the impacts of climate change on mountaineering routes in the Écrins massif over the past 50 years, based on the "Le massif des Écrins - Les 100 plus belles courses et randonnées" guide. To do this, we used a method initially developed for the Mont-Blanc massif and extended for the Valais Alps with a cartographic approach, to identify and map the geomorphological and glaciological processes affecting mountaineering routes. The aim was to extend the corpus of massifs studied to include a more southerly, lower-altitude massif such as the Écrins.

38

The specific parameters of the Écrins massif, such as its lower altitude and southern
location, led us to add a process to the cartographic legend developed for the Valais:
the earlier summer melting of ice-snow covers.

39

A total of 70 routes were analyzed. On average, a route is affected by 9 processes, as in the Mont-Blanc massif and the Valais. The three processes affecting the greatest number of routes are glacier retreat, steeper glaciers, and glacier surfaces that are more often bare ice. On the other hand, among the 70 itineraries studied, 2 are not affected by climate change, 30 are slightly affected, 22 are moderately affected, and 16 are severely affected and can no longer be climbed in summer (mostly snow or mixed itineraries with difficulty above D). As a result, there has been a change in seasonality for some routes of this type, which are no longer visited in summer, but increasingly in winter or spring. In addition, 7 routes have changed their nature and are now mixed or rocky. These routes have lost their technical and aesthetic appeal and are therefore less popular today. The impact of climate change on mountaineering routes in the
Écrins is therefore considerable, and this has a direct influence on accessibility, seasonality and practice methods.

40

On the other hand, some routes are positively affected in certain sections, mainly due to less exposure to serac falls or a reduction in their frequency. This is not the case for the massif's two highest peaks, the Dôme and the Barre des Écrins, whose main access route is, on the contrary, experiencing an increase in serac falls.

41

This work provides a complementary corpus for comparing the evolution of mountaineering routes in the three major mountaineering massifs in the western Alps: Mont-Blanc, Écrins and the Valais Alps. On the basis of the observations made in the southernmost massif of this triptych, it seems appropriate to consider the future of the ice caps in the other Alpine massifs, since they are also likely to disappear in the coming years/decades. On the other hand, from a more sociological point of view, it remains to be documented how the changes observed are likely to affect the imaginary of mountaineering in the three massifs, and especially in the Écrins.

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## Bibliography

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Etzelmüller, B., Guglielmin, M., Hauck, C., & Ramos, M. (2020). Twenty years of European mountain permafrost dynamics: The PACE legacy. *Environmental Research Letters*, 15(10), 104070. https://doi.org/10.1088/1748-9326/abae9d

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Harris, C., Davies, M. C., & Etzelmüller, B. (2001). The assessment of potential geotechnical hazards associated with mountain permafrost in a warming global climate. *Permafrost and Periglacial Processes*, 12(1), 145-156. https://doi.org/10.1002/ppp.376

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Hugonnet, R., McNabb, R., Berthier, E., & Kääb, A. (2021). Accelerated global glacier mass loss in the early twenty-first century. *Nature*, 592, 726-731. https://doi.org/10.1038/s41586-021-03436-z

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Kaushik, S., Ravanel, L., Magnin, F., & Yan, Y. (2022). Ice aprons in the Mont Blanc Massif (Western European Alps): Topographic characteristics and relations with glaciers and other types of perennial surface ice features. *Remote Sensing*, 14, 5557. https://doi.org/10.3390/rs14215557

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Magnin, F., Brenning, A., Bodin, X., Deline, P., & Ravanel, L. (2015). Modélisation statistique de la distribution du permafrost de paroi: Application au massif du Mont Blanc. *Géomorphologie : Relief, processus, environnement*, 21(2). https://doi.org/10.4000/geomorphologie.10965

Magnin, F., Ravanel, L., Bodin, X., Deline, P., Malet, E., et al. (2023). Main results of permafrost monitoring in the French Alps through the PermaFrance network over the period 2010-2022. *Permafrost and Periglacial Processes*, 35(1). https://doi.org/10.1002/ppp.2209

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Mourey, J., Marcuzzi, M., Ravanel, L., & Pallandre, F. (2019a). Effects of climate change on high Alpine environments: Evolution of mountaineering routes in the Mont Blanc massif (Western Alps) over half a century. *Arctic, Antarctic, and Alpine Research*, 51(1), 176-189. https://doi.org/10.1080/15230430.2019.1612216
Mourey, J., Ravanel, L., Lambiel, C., Strecker, J., & Piccardi, M. (2019b). Access routes to high mountain huts facing climate-induced environmental changes and adaptive strategies in the Western Alps since the 1990s. *Norwegian Journal of Geography*, 73(4), 215-228. https://doi.org/10.1080/00291951.2019.1689163

Mourey, J., Ravanel, L., & Lambiel, C. (2022). Climate change related processes affecting mountaineering itineraries, mapping and application to the Valais Alps (Switzerland). *Geografiska Annaler: Series A, Physical Geography*. https://doi.org/10.1080/04353676.2022.2064651

Purdie, H., & Kerr, T. (2018). Aoraki Mont Cook: Environmental change on an iconic mountaineering route. *Mountain Research and Development*, 38(4), 364-379. https://doi.org/10.1659/MRD-JOURNAL-D-18-00042.1

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# ANNEXES

## Appendix

### Appendix 1 : Routes studied

<table><thead><tr><th>Routier</th><th>Série d'Alps</th><th>Routes</th></tr></thead><tbody><tr><td>1</td><td>Alps du Mont-Blanc</td><td>Tour du Mont-Blanc</td></tr><tr><td>2</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (1er circuit)</td></tr><tr><td>3</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (2e circuit)</td></tr><tr><td>4</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (3e circuit)</td></tr><tr><td>5</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (4e circuit)</td></tr><tr><td>6</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (5e circuit)</td></tr><tr><td>7</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (6e circuit)</td></tr><tr><td>8</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (7e circuit)</td></tr><tr><td>9</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (8e circuit)</td></tr><tr><td>10</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (9e circuit)</td></tr><tr><td>11</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (10e circuit)</td></tr><tr><td>12</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (11e circuit)</td></tr><tr><td>13</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (12e circuit)</td></tr><tr><td>14</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (13e circuit)</td></tr><tr><td>15</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (14e circuit)</td></tr><tr><td>16</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (15e circuit)</td></tr><tr><td>17</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (16e circuit)</td></tr><tr><td>18</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (17e circuit)</td></tr><tr><td>19</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (18e circuit)</td></tr><tr><td>20</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (19e circuit)</td></tr><tr><td>21</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (20e circuit)</td></tr><tr><td>22</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (21e circuit)</td></tr><tr><td>23</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (22e circuit)</td></tr><tr><td>24</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (23e circuit)</td></tr><tr><td>25</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (24e circuit)</td></tr><tr><td>26</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (25e circuit)</td></tr><tr><td>27</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (26e circuit)</td></tr><tr><td>28</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (27e circuit)</td></tr><tr><td>29</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (28e circuit)</td></tr><tr><td>30</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (29e circuit)</td></tr><tr><td>31</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (30e circuit)</td></tr><tr><td>32</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (31e circuit)</td></tr><tr><td>33</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (32e circuit)</td></tr><tr><td>34</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (33e circuit)</td></tr><tr><td>35</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (34e circuit)</td></tr><tr><td>36</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (35e circuit)</td></tr><tr><td>37</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (36e circuit)</td></tr><tr><td>38</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (37e circuit)</td></tr><tr><td>39</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (38e circuit)</td></tr><tr><td>40</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (39e circuit)</td></tr><tr><td>41</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (40e circuit)</td></tr><tr><td>42</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (41e circuit)</td></tr><tr><td>43</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (42e circuit)</td></tr><tr><td>44</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (43e circuit)</td></tr><tr><td>45</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (44e circuit)</td></tr><tr><td>46</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (45e circuit)</td></tr><tr><td>47</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (46e circuit)</td></tr><tr><td>48</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (47e circuit)</td></tr><tr><td>49</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (48e circuit)</td></tr><tr><td>50</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (49e circuit)</td></tr><tr><td>51</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (50e circuit)</td></tr><tr><td>52</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (51e circuit)</td></tr><tr><td>53</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (52e circuit)</td></tr><tr><td>54</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (53e circuit)</td></tr><tr><td>55</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (54e circuit)</td></tr><tr><td>56</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (55e circuit)</td></tr><tr><td>57</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (56e circuit)</td></tr><tr><td>58</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (57e circuit)</td></tr><tr><td>59</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (58e circuit)</td></tr><tr><td>60</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (59e circuit)</td></tr><tr><td>61</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (60e circuit)</td></tr><tr><td>62</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (61e circuit)</td></tr><tr><td>63</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (62e circuit)</td></tr><tr><td>64</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (63e circuit)</td></tr><tr><td>65</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (64e circuit)</td></tr><tr><td>66</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (65e circuit)</td></tr><tr><td>67</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (66e circuit)</td></tr><tr><td>68</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (67e circuit)</td></tr><tr><td>69</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (68e circuit)</td></tr><tr><td>70</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (69e circuit)</td></tr><tr><td>71</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (70e circuit)</td></tr><tr><td>72</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (71e circuit)</td></tr><tr><td>73</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (72e circuit)</td></tr><tr><td>74</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (73e circuit)</td></tr><tr><td>75</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (74e circuit)</td></tr><tr><td>76</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (75e circuit)</td></tr><tr><td>77</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (76e circuit)</td></tr><tr><td>78</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (77e circuit)</td></tr><tr><td>79</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (78e circuit)</td></tr><tr><td>80</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (79e circuit)</td></tr><tr><td>81</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (80e circuit)</td></tr><tr><td>82</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (81e circuit)</td></tr><tr><td>83</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (82e circuit)</td></tr><tr><td>84</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (83e circuit)</td></tr><tr><td>85</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (84e circuit)</td></tr><tr><td>86</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (85e circuit)</td></tr><tr><td>87</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (86e circuit)</td></tr><tr><td>88</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (87e circuit)</td></tr><tr><td>89</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (88e circuit)</td></tr><tr><td>90</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (89e circuit)</td></tr><tr><td>91</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (90e circuit)</td></tr><tr><td>92</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (91e circuit)</td></tr><tr><td>93</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (92e circuit)</td></tr><tr><td>94</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (93e circuit)</td></tr><tr><td>95</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (94e circuit)</td></tr><tr><td>96</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (95e circuit)</td></tr><tr><td>97</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (96e circuit)</td></tr><tr><td>98</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (97e circuit)</td></tr><tr><td>99</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (98e circuit)</td></tr><tr><td>100</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (99e circuit)</td></tr><tr><td>101</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (100e circuit)</td></tr><tr><td>102</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (101e circuit)</td></tr><tr><td>103</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (102e circuit)</td></tr><tr><td>104</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (103e circuit)</td></tr><tr><td>105</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (104e circuit)</td></tr><tr><td>106</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (105e circuit)</td></tr><tr><td>107</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (106e circuit)</td></tr><tr><td>108</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (107e circuit)</td></tr><tr><td>109</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (108e circuit)</td></tr><tr><td>110</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (109e circuit)</td></tr><tr><td>111</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (110e circuit)</td></tr><tr><td>112</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (111e circuit)</td></tr><tr><td>113</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (112e circuit)</td></tr><tr><td>114</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (113e circuit)</td></tr><tr><td>115</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (114e circuit)</td></tr><tr><td>116</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (115e circuit)</td></tr><tr><td>117</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (116e circuit)</td></tr><tr><td>118</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (117e circuit)</td></tr><tr><td>119</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (118e circuit)</td></tr><tr><td>120</td><td>Alps du Mont-Blanc</td><td>Alps du Mont-Blanc (119e circuit)</td></tr></tbody></table>

### Appendix 2 – Routes not studied
<table><thead><tr><th>Number</th><th>Summit Name</th><th>Routes</th></tr></thead><tbody><tr><td>1/2</td><td></td><td>Tour et intérieur du massif</td></tr><tr><td>3</td><td>Arêtes de la Bruyère</td><td>Traversée nord-ouest/sud-est</td></tr><tr><td>4</td><td>Tête Noire</td><td>Voie de la Poire</td></tr><tr><td>5</td><td>Aiguille du Lauzet</td><td>Couler Davin</td></tr><tr><td>6</td><td>Tête de Colombe</td><td>Voie de l'Écaillie</td></tr><tr><td>7</td><td>Crête de Queyrellin</td><td>Face nord-ouest</td></tr><tr><td>8</td><td>Tête Noire</td><td>Voie des Grands Surplombs</td></tr><tr><td>9</td><td>Tenailles de Montbrison</td><td>Eperon Renaud</td></tr><tr><td>22</td><td>Aiguille d'Olan</td><td>Versant sud-est (voie normale)</td></tr><tr><td>32</td><td>Aiguille du Plat de la Selle</td><td>Traversée</td></tr><tr><td>35</td><td>Tour carrière de Roche Méline</td><td>Face sud</td></tr><tr><td>41</td><td>Tête de Lauranoure</td><td>Eperon ouest</td></tr><tr><td>42</td><td>Les Bans sommet nord-ouest</td><td>Versant ouest (voie Reynier)</td></tr><tr><td>43</td><td>Les Routes</td><td>Face est et traversée</td></tr><tr><td>44</td><td>Bec de Canard - Aiguille des Arias</td><td>Traversée</td></tr><tr><td>45</td><td>Tour Chosy - Pic Bourcet</td><td>Traversée</td></tr><tr><td>48</td><td>Aiguille Dibona</td><td>Face sud</td></tr><tr><td>51</td><td>Pointe des Angles</td><td>Arête Ouest</td></tr><tr><td>52</td><td>La Rouye</td><td>Face ouest</td></tr><tr><td>53</td><td>Trois Dents du Pelvoux</td><td>Arête nord-est</td></tr><tr><td>54</td><td>Pointe du Vallon des Etages</td><td>Face sud</td></tr><tr><td>55</td><td>Les Bans</td><td>Versant sud-est</td></tr><tr><td>59</td><td>Aleuroide occidentale</td><td>Glacier long</td></tr><tr><td>62</td><td>Pointe Thorant</td><td>Face est</td></tr><tr><td>64</td><td>Barre des Écrins</td><td>Face sud-est</td></tr><tr><td>66</td><td>Aiguille de la Gandolière</td><td>Piler nord</td></tr><tr><td>67</td><td>Le Pavé</td><td>Face sud</td></tr><tr><td>69</td><td>Pelvoux Pointe Purseux</td><td>Arête nord</td></tr><tr><td>72</td><td>Pic nord du Loup</td><td>Face nord-nord-ouest</td></tr><tr><td>73</td><td>Aiguille Dibona</td><td>Voie des Savoyards</td></tr><tr><td>74</td><td>Rateau sommet ouest</td><td>Face nord-nord-est</td></tr><tr><td>76</td><td>Pic Gaspard</td><td>Arête sud-sud-est</td></tr><tr><td>77</td><td>Tête de l'Ebret</td><td>Versant nord-est</td></tr><tr><td>80</td><td>Pointe du Vallon des Etages</td><td>Face nord</td></tr><tr><td>82</td><td>Olan sommet central</td><td>Paroi nord-ouest</td></tr><tr><td>84</td><td>Aiguille de Sialouze</td><td>Face sud-ouest</td></tr><tr><td>85</td><td>Les Bans</td><td>Face sud-est</td></tr><tr><td>88</td><td>Dôme de Neige des Écrins</td><td>Versant nord-ouest</td></tr><tr><td>89</td><td>Pic Sans Nom</td><td>Face ouest</td></tr><tr><td>91</td><td>Pic Gaspard</td><td>Face nord</td></tr><tr><td>94</td><td>Moie Troisième Dent</td><td>Face sud directe</td></tr><tr><td>95</td><td>Pic Sans Nom</td><td>Face nord</td></tr><tr><td>96</td><td>Pic Sans Nom Épaule est</td><td>Piler Nord</td></tr><tr><td>97</td><td>Le Râteau</td><td>Face Nord</td></tr></tbody></table>

## RÉSUMÉS

Mountaineering is one of the most affected sports activities due to the current climate crisis and the resulting changes in the physical environment of the high mountain areas. Some routes have disappeared while others are no longer accessible in summer (hazards, technical difficulties, etc.). Research has already been conducted on the impact of climate change on mountaineering and on adaptation. The Mont-Blanc massif and the Valais Alps have been used as study areas to understand the evolution of mountaineering routes over recent decades. A mapping of the geomorphological and glaciological processes affecting mountaineering routes has been conducted for the Valais. This study aims to apply this method to Écrins massif (French Alps), which had so far remained unstudied despite its emblematic character. The famous topo-guide "Le massif des Écrins - Les 100 plus belles courses et randonnées" (1974) was used as a basis for the study with 70 routes being selected according to their notoriety and visitor numbers. All the processes affecting the routes were mapped using GIS, and a statistical analysis was carried out to gain a better understanding of the evolution of the routes, together with semi-directive interviews with experts and practitioners. A new process – the early summer melting of ice and snow cover – was identified. As is the case in the Mont-Blanc massif and the Valais, a route is affected by 9 processes on average, and almost 25% of the routes can no longer be climbed in summer. The mapping method has been successfully applied to Écrins massif, providing new knowledge of the recent evolution of mountaineering routes in the Alps.

## INDEX

**Keywords** : mountaineering routes, glaciers, permafrost, climate change, Écrins massif
AUTEURS

MATHIS ARNAUD

Parc national des Écrins, France

JACQUES MOUREY

Laboratoire EDYTEM, Univ. Savoie Mont-Blanc, CNRS (UMR 5204), Le Bourget du Lac, France

PHILIPPE BOURDEAU

Univ. Grenoble-Alpes, UMR PACTE CNRS, LabEx ITTEM, Grenoble, France

RICHARD BONET

Parc national des Écrins, France

LUDOVIC RAVANEL

Laboratoire EDYTEM, Univ. Savoie Mont-Blanc, CNRS (UMR 5204), Le Bourget du Lac, France