Pôle Alpin Risques Naturels (PARN) Alpes–Climat–Risques Avec le soutien de la Région Rhône-Alpes (2007-2014)
FR
EN
 


Fiche bibliographique

 

Réf. Berthier E. & Vincent C. 2012

Référence bibliographique
BERTHIER E. & VINCENT C., Relative contribution of surface mass-balance and ice-flux changes to the accelerated thinning of Mer de Glace, French Alps, over 1979–2008. Journal of Glaciology, Vol. 58, No. 209.

Abstract: By subtracting surface topographies from 1979, 1994, 2000 and 2008, we measured icethinning rates increasing from 1ma–1 (1979–94) to >4ma–1 (2000–08) on the tongue of Mer de Glace, French Alps. The relative contributions of changes in surface mass balance and ice fluxes to this acceleration in the thinning are estimated using field and remote-sensing measurements. Between 1979–94 and 2000–08, surface mass balance diminished by 1.2mw.e. a–1, mainly because of atmospheric warming. Mass-balance changes induced by the growing debris-covered area and the evolving glacier hypsometry compensated each other. Meanwhile, Mer de Glace slowed down and the ice fluxes through two cross sections at 2200 and 2050ma.s.l. decreased by 60%. Between 1979–94 and 2000–08, two-thirds of the increase in the thinning rates was caused by reduced ice fluxes and onethird by rising surface ablation. However, these numbers need to be interpreted cautiously given our inability to respect mass conservation below our upper cross section. An important implication is that large errors would occur if one term of the continuity equation (e.g. surface mass balance) were deduced from the two others (e.g. elevation and ice-flux changes).

Mots-clés
 

Organismes / Contact
  • Centre National de la Recherche Scientifique, Universite´ de Toulouse, LEGOS, Toulouse, France
  • Laboratoire de Glaciologie et Ge´ophysique de l’Environnement, CNRS/Universite´ Joseph Fourier, Grenoble, France
  • Corresponding author: etienne.berthier@legos.obs-mip.fr

(1) - Paramètre(s) atmosphérique(s) modifié(s)
(2) - Elément(s) du milieu impacté(s)
(3) - Type(s) d'aléa impacté(s)
(3) - Sous-type(s) d'aléa
  surface mass balance, ice fluxes ice thinning rate, glacier retreat  

Pays / Zone
Massif / Secteur
Site(s) d'étude
Exposition
Altitude
Période(s) d'observation
france French Alps Mer de Glace     1979-2008

(1) - Modifications des paramètres atmosphériques
Reconstitutions
 
Observations
 
Modélisations
 
Hypothèses
 

Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 

(2) - Effets du changement climatique sur le milieu naturel
Reconstitutions

Field measurements at ablation stakes

Each year in late September, the annual surface mass balance on Mer de Glace is determined below 2300m using an ablation stake network mainly located along the glacier center line. The annual mass balance varies from about –4mw.e. a–1 at 2300m to –9mw.e. a–1 at the lowest ablation stake (1750 m). All annual mass-balance measurements available on clean ice between hydrological years 1979/80 and 2007/08 are processed using the linear mass balance model (Lliboutry, 1974) and are corrected for local elevation changes.

Mesures de terrain au niveau des sondes d’ablation

Chaque année, fin septembre, le bilan de masse annuel de la Mer de Glace est calculé, sur la zone située sous 2300m, en utilisant un réseau de sondes d’ablation, principalement située autour de la ligne centrale du glacier. Le bilan de masse annuel varie d’environ -4me.e par an à 2300m et de -9me.e par an au niveau des sondes les plus basses (1750m).Toutes les mesures des bilans de masse, effectués sur glace « propre », entre les années hydrologiques 1979/80 et 2007/08 ont été réalisées en suivant le modèle linéaire de reconstruction des bilans de masse (Lliboutry, 1974) et ont été corrigé en suivant les variations locales d’altitude.

Observations
 Thinning rate

By subtracting surface topographies from 1979, 1994, 2000 and 2008, we measured icethinning rates increasing from 1ma–1 (1979–94) to >4ma–1 (2000–08) on the tongue of Mer de Glace, French Alps.

Between 1979–94 and 2000–08, two-thirds of the increase in the thinning rates was caused by reduced ice fluxes and onethird by rising surface ablation. However, these numbers need to be interpreted cautiously given our inability to respect mass conservation below our upper cross section. An important implication is that large errors would occur if one term of the continuity equation (e.g. surface mass balance) were deduced from the two others (e.g. elevation and ice-flux changes).

Between a flux gate (noted as FGTRE; Fig. 1b) at about 2050m in 1979 and the glacier front (a glacierized area of about 2 km2), the average ice-thinning rate has evolved from 0.60.1ma–1 in 1979–94 (referred to as epoch I in the following) to 3.00.3ma–1 in 1994–2000 (epoch II) and 4.00.2ma–1 in 2000–08 (epoch III). In other words, the ice-thinning rate has increased by 2.40.4ma–1 (from epoch I to II) and then by 1.00.4ma–1 (from epoch II to III).

Between another flux gate (noted as FGTAC; Fig. 1b) at higher altitude (about 2225m in 1979) the ice-thinning rate has increased by 1.70.4ma–1 (from epoch I to II) and 1.00.4ma–1 (from epoch II to III).

Mass balance

Between 1979–94 and 2000–08, surface mass balance diminished by 1.2mw.e. a–1, mainly because of atmospheric warming. Mass-balance changes induced by the growing debris-covered area and the evolving glacier hypsometry compensated each other. Meanwhile, Mer de Glace slowed down and the ice fluxes through two cross sections at 2200 and 2050ma.s.l. decreased by 60%.

Interestingly, the massbalance changes between the different periods for the whole tongue are close to the mass-balance temporal anomaly (t) determined at ablation stakes located on clean ice only. This indicates that the main driver of mass-balance change on the Mer de Glace tongue is climate change, whereas other feedbacks potentially influencing the mass balance (growing debris coverage, thinning of the tongue and area loss close to the glacier front) nearly compensate each other in term of ablation feedbacks, thinning dominates over the retreat of the front.

Taux d’amincissement

En soustrayant les surfaces topographiques de 1979, 1994, 2000 et 2008, nous avons pu mesurer, sur la langue de la Mer de Glace (Alpes Françaises), une augmentation des taux d’amincissement de 1m par an (1979-94) à plus de 4m (2000-08).

Entre 1979-94 et 2000-08, deux tiers de l’augmentation des taux d’amincissement de la glace ont été causé par la diminution de l’écoulement glaciaire et un tiers par l’augmentation de la surface d’ablation. Cependant, étant donné notre incapacité à connaître l’évolution de la masse au-dessus et au-dessous de la zone d’étude, ces chiffres doivent être maniés avec circonspection. Une conséquence importante serait l’apparition d’erreurs importantes si jamais un des termes de l’équation de continuité (par exemple la surface du bilan de masse) était déduit des deux autres variables (par exemple l’altitude et les variations d’écoulements glaciaires).

Entre une porte d’écoulement à environ 2050m en 1979 et le front du glacier (une zone englacée d’environ 2km²), le taux moyen de d’amincissement de la glace a évolué de 0.6 +/- 0.1m par an en 1979-94 à 3.0 +/- 0.3m par en en 1994-2000 et à 4.0+/- 0.2m par an en 2000-08. En d’autres mots, le taux d’amincissement a augmenté de 2.4 +/- 0.4 m par an dans un premier temps, puis de 1.0+/-0.4m par an dans un second.

La différence entre une autre porte d’écoulement, situé à plus haute altitude (2225m en 1979) et le front du glacier, le taux moyen d’amincissement a évolué de 1.7+/-0.4m par an à 1.0+/-0.4m par an.

Bilan de masse

Entre 1979-94 et 2000-08, le bilan de masse a diminué de 1.2me.e par an et ce, majoritairement à cause du réchauffement climatique. Les variations du bilan de masse résultant de l’augmentation de la couverture détritique et l’évolution de l’hypsométrie du glacier se compensent l’un l’autre. On observe également un ralentissement de la Mer de Glace et de l’écoulement glaciaire qui, entre les deux zones d’étude à 2200 et 2050m diminue de 60%.

Fait intéressant, les variations du bilan de masse, entre les différentes périodes d’étude, sur la langue de la Mer de Glace, sont assez proches de l’anomalie temporelle du bilan de masse mesuré au niveau des sondes d’ablation disposées sur la glace « propre ». Cette observation montre que le moteur principal des variations du bilan de masse de la Mer de Glace est le changement climatique, et non pas les paramètres extérieurs (augmentation de la couverture détritique, amincissement de la langue terminale et des zones proches du front du glacier) qui se compensent les uns les autres en termes d’influence sur les taux d’ablation, d’influence sur le retrait plus ou moins rapide de la langue terminale.

Modélisations
 
Hypothèses
 

Sensibilité du milieu à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 A reduction in the ice fluxes exerts a strong control on the geometry of glaciers by starving their lowest elevations and preserving their upper reaches. The prevalence of this geometric response is confirmed by the observation of limited thinning in the accumulation zone for a large number of glaciers in the European Alps during the past two to three decades
La reduction des écoulements glaciaires excerce un fort contrôle sur la géométrie du glacier en arrêtant d’alimenter les parties basses, et en préservant le volume des parties hautes. La prédominance de cette réponse géométrique est confirmée par les observations de fonte limitée dans la zone d’accumulation pour un grand nombre de glaciers dans les alpes européennes au cours des deux dernières décénnnies
 Thus, although remote-sensing techniques have reached a certain level of maturity to observe velocity fields or glacierwide averaged mass balances, dense networks of ablation stakes on selected glaciers seem to remain the best means to assess the spatial pattern and temporal changes in their mass balance and thus the influence of climate change.
Ainsi, bien que les techniques de télédétection spatiale optique aient atteint un niveau de précision suffisant pour observer les variations de vitesse sur le terrain ou analyser les évolutions du bilan de masse d’un glacier, la mise en place d’un réseau conséquent de sondes d’ablation semble être la meilleure méthode pour valider le modèle spatial et les évolutions temporelles de leur bilan de masse et, par conséquent, évaluer l’influence du changement climatique.

(3) - Effets du changement climatique sur l'aléa
Reconstitutions
 
Observations
 
Modélisations
 
Hypothèses
 

Paramètre de l'aléa
Sensibilité du paramètres de l'aléa à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 
 
 

(4) - Remarques générales
 

(5) - Syntèses et préconisations
 

Références citées :

Arnold NS, Rees WG, Hodson AJ and Kohler J (2006) Topographic controls on the surface energy balance of a high Arctic valley glacier. J. Geophys. Res., 111(F2), F02011 (doi: 10.1029/ 2005JF000426)

Bauder A, Funk M and Huss M (2007) Ice-volume changes of selected glaciers in the Swiss Alps since the end of the 19th century. Ann. Glaciol., 46, 145–149 (doi: 10.3189/ 172756407782871701)

Berthier E (2007) Dynamique et bilan de masse des glaciers de montagne (Alpes, Islande, Himalaya). Contribution de l’imagerie satellitaire. Houille Blanche 2, 116–121 (doi: 10.1051/ lhb:2007028)

Berthier E, Raup BH and Scambos TA (2003) New velocity map and mass-balance estimate of Mertz Glacier, East Antarctica, derived from Landsat sequential imagery. J. Glaciol., 49(167), 503–511 (doi: 10.3189/172756503781830377)

Berthier E, Arnaud Y, Baratoux D, Vincent C and Re´my F (2004) Recent rapid thinning of the Mer de Glace glacier derived from satellite optical images. Geophys. Res. Lett., 31(17), L17401 (doi: 10.1029/2004GL020706)

Berthier E and 7 others (2005) Surface motion of mountain glaciers derived from satellite optical imagery. Remote Sens. Environ., 95(1), 14–28 doi: 10.1016/j.rse.2004.11.005)

Berthier E, Arnaud Y, Vincent C and Re´my F (2006) Biases of SRTM in high-mountain areas: implications for the monitoring of glacier volume changes. Geophys. Res. Lett., 33(8), L08502 (doi: 10.1029/2006GL025862)

Berthier E, Schiefer E, Clarke GKC, Menounos B and Re´my F (2010) Contribution of Alaskan glaciers to sea-level rise derived from satellite imagery. Nature Geosci., 3(2), 92–95 (doi: 10.1038/ ngeo737)

Cuffey KM and Paterson WSB (2010) The physics of glaciers, 4th edn.

Butterworth-Heinemann, Oxford Deline P (2005) Change in surface debris cover on Mont Blanc massif glaciers after the ‘Little Ice Age’ termination. Holocene, 15(2), 302–309 (doi: 10.1191/0959683605hl809rr)

Dyurgerov MB and Meier MF (1999) Analysis of winter and summer glacier mass balances. Geogr. Ann., 81A(4), 541–554

Elsberg DH, Harrison WD, Echelmeyer KA and Krimmel RM (2001) Quantifying the effects of climate and surface change on glacier mass balance. J. Glaciol., 47(159), 649–658 (doi: 10.3189/ 172756501781831783)

Gluck S (1967) De´termination du lit rocheux sous la Mer de Glace par se´ismique-re´flexion. C. R. Acad. Sci. (Paris), 264(19), 2272–2275

Gudmundsson GH and Bauder A (1999) Towards an indirect determination of the mass-balance distribution of glaciers using the kinematic boundary condition. Geogr. Ann., 81A(4), 575–583

Hagen JO, Eiken T, Kohler J and Melvold K (2005) Geometry changes on Svalbard glaciers: mass-balance or dynamic response? Ann. Glaciol., 42, 255–261 (doi: 10.3189/172756405781812763)

Heid T and Ka¨a¨b A (2011) Worldwide widespread decadal-scale decrease of glacier speed revealed using repeat optical satellite images. Cryos. Discuss., 5(5), 3025–3051 (doi: 10.5194/tcd-5- 3025-2011)

Hubbard A and 6 others (2000) Glacier mass-balance determination by remote sensing and high-resolution modelling. J. Glaciol., 46(154), 491–498 (doi: 10.3189/172756500781833016)

Huss M, Sugiyama S, Bauder A and Funk M (2007) Retreat scenarios of Unteraargletscher, Switzerland, using a combined ice-flow mass-balance model. Arct. Antarct. Alp. Res., 39(3), 422–431

Huss M, Bauder A, Funk M and Hock R (2008) Determination of the seasonal mass balance of four Alpine glaciers since 1865. J. Geophys. Res., 113(F1), F01015 (doi: 10.1029/2007JF000803)

Ka¨a¨b A (2000) Photogrammetric reconstruction of glacier mass balance using a kinematic ice-flow model: a 20 year time series on Grubengletscher, Swiss Alps. Ann. Glaciol., 31, 45–52 (doi: 10.3189/172756400781819978)

Ka¨a¨b A and Funk M (1999) Modelling mass balance using photogrammetric and geophysical data: a pilot study at Griesgletscher, Swiss Alps. J. Glaciol., 45(151), 575–583

Kirkbride MPandWarren CR (1999) Tasman Glacier, New Zealand: 20th-century thinning and predicted calving retreat. Global Planet. Change, 22(1–4), 11–28

Kohler J and 7 others (2007) Acceleration in thinning rate on western Svalbard glaciers. Geophys. Res. Lett., 34(18), L18502 (doi: 10.1029/2007GL030681)

Lambrecht A and Kuhn M (2007) Glacier changes in the Austrian Alps during the last three decades, derived from the new Austrian glacier inventory. Ann. Glaciol., 46, 177–184 (doi: 10.3189/172756407782871341)

Lemke P and 10 others (2007) Observations: changes in snow, ice and frozen ground. In Solomon S and 7 others eds. Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, 339–383

Lliboutry L (1974) Multivariate statistical analysis of glacier annual balances. J. Glaciol., 13(69), 371–392

Lliboutry L and Reynaud L (1981) ‘Global dynamics’ of a temperate valley glacier, Mer de Glace, and past velocities deduced from Forbes’ bands. J. Glaciol., 27(96), 207–226

Magnu´sson E, Bjo¨rnsson H, Dall J and Pa´lsson F (2005) Volume changes of Vatnajo¨ kull ice cap, Iceland, due to surface mass balance, ice flow, and subglacial melting at geothermal areas. Geophys. Res. Lett., 32(5), L05504 (doi: 10.1029/ 2004GL021615)

Mihalcea C, Mayer C, Diolaiuti G, Lambrecht A, Smiraglia C and Tartari G (2006) Ice ablation and meteorological conditions on the debris-covered area of Baltoro glacier, Karakoram, Pakistan. Ann. Glaciol., 43, 292–300 (doi: 10.3189/172756406781812104)

Nuimura T, Fujita K, Fukui K, Asahi K, Aryal R and Ageta Y (2011) Temporal changes in elevation of the debris-covered ablation area of Khumbu glacier in the Nepal Himalaya since 1978. Arct. Antarct. Alp. Res., 43(2), 246–255

Nuth C, Moholdt G, Kohler J, Hagen JO and Ka¨a¨b A (2010) Svalbard glacier elevation changes and contribution to sea level rise. J. Geophys. Res., 115(F1), F01008 (doi: 10.1029/ 2008JF001223)

Nuth C, Schuler TV, Kohler J, Altena B and Hagen JO (2012) Estimating the long-term calving flux of Kronebreen, Svalbard, from geodetic elevation changes and mass-balance modelling. J. Glaciol., 58(207), 119–133 (doi: 10.3189/2012JoG11J036)

Oerlemans J (2001) Glaciers and climate change, AA Balkema, Lisse Oerlemans J, Giesen RH and Van den Broeke MR (2009) Retreating alpine glaciers: increased melt rates due to accumulation of dust (Vadret da Morterastch, Switzerland). J. Glaciol., 55(192), 729–736 (doi: 10.3189/002214309789470969)

Ohmura A (2006) Changes in mountain glaciers and ice caps during the 20th century. Ann. Glaciol., 43, 361–368 (doi: 10.3189/172756406781812212)

Paul F and Haeberli W (2008) Spatial variability of glacier elevation changes in the Swiss Alps obtained from two digital elevation models. Geophys. Res. Lett., 35(21), L21502 (doi: 10.1029/ 2008GL034718)

Paul F, Ka¨a¨b A and HaeberliW(2007) Recent glacier changes in the Alps observed from satellite: consequences for future monitoring strategies. Global Planet. Change, 56(1–2), 111–122

Rabatel A, Dedieu J-P and Vincent C (2005) Using remotesensing data to determine equilibrium-line altitude and massbalance time series: validation on three French glaciers, 1994–2002. J. Glaciol., 51(175), 539–546 (doi: 10.3189/ 172756505781829106)

Raymond CF (1971) Flow in a transverse section of Athabasca Glacier, Alberta, Canada. J. Glaciol., 10(58), 55–84 Reynaud L (1973) Etude de la dynamique des se´racs du Ge´ant (Massif du Mont-Blanc). (PhD thesis, Universite´ Scientifique et Me´dicale, Grenoble)

Reynaud L, Vallon M and Letre´guilly A (1986) Mass-balance measurements: problems and two new methods of determining variations. J. Glaciol., 32(112), 446–454

Rignot E, Rivera A and Casassa G (2003) Contribution of the Patagonian icefields of South America to sea level rise. Science, 302(5644), 434–437 (doi: 10.1126/science.1087393)

Sakai A, Takeuchi N, Fujita K and Nakawo M (2000) Role of supraglacial ponds in the ablation process of a debris-covered glacier in the Nepal Himalayas. IAHS Publ. 264 (Symposium at Seattle 2000 – Debris-Covered Glaciers), 119–130

Sakai A, Nakawo M and Fujita K (2002) Distribution characteristics and energy balance of ice cliffs on debris-covered glaciers, Nepal Himalaya. Arct. Antarct. Alp. Res., 34(1), 12–19

Sakai A, Fujita K, Duan K, Pu J, Nakawo M and Yao T (2006) Five decades of shrinkage of July 1st glacier, Qilian Shan, China. J. Glaciol., 52(176), 11–16 (doi: 10.3189/ 172756506781828836)

Schwitter MP and Raymond CF (1993) Changes in the longitudinal profiles of glaciers during advance and retreat. J. Glaciol., 39(133), 582–590

Soruco A, Vincent C, Francou B and Gonzalez JF (2009) Glacier decline between 1963 and 2006 in the Cordillera Real, Bolivia. Geophys. Res. Lett., 36(3), L03502 (doi: 10.1029/ 2008GL036238)

Span N and Kuhn M (2003) Simulating annual glacier flow with a linear reservoir model. J. Geophys. Res., 108(D10), 4313 (doi: 10.1029/2002JD002828)

Surazakov AB and Aizen VB (2006) Estimating volume change of mountain glaciers using SRTM and map-based topographic data. IEEE Trans. Geosci. Remote Sens., 44(10), 2991–2995 (doi: 10.1109/TGRS.2006.875357)

Su¨sstrunk AE (1951) Sondage du glacier par la me´thode sismique. Houille Blanche, No. spe´cial A, 309–318 (doi: 10.1051/lhb/ 1951010)

Thibert E and Vincent C (2009) Best possible estimation of mass balance combining glaciological and geodetic methods. Ann. Glaciol., 50(50), 112–118 (doi: 10.3189/172756409787769546)

Vallon M (1961) E´paisseur du glacier du Tacul (massif du Mont- Blanc). C. R. Se´ances Acad. Sci. (Paris), 252(12), 1815–1817 Vallon M (1967) Contribution a` l’e´tude de la Mer de Glace. (PhD thesis, Universite´ de Grenoble)

Vincent C (2002) Influence of climate change over the 20th century on four French glacier mass balances. J. Geophys. Res., 107(D19), 4375 (doi: 10.1029/2001JD000832)

Vincent C, Vallon M, Reynaud L and Le Meur E (2000) Dynamic behaviour analysis of glacier de Saint Sorlin, France, from 40 years of observations, 1957–97. J. Glaciol., 46(154), 499–506 (doi: 10.3189/172756500781833052)

Vincent C, Kappenberger G, Valla F, Bauder A, Funk M and Le Meur E (2004) Ice ablation as evidence of climate change in the Alps over the 20th century. J. Geophys. Res., 109(D10), D10104 (doi: 10.1029/2003JD003857)

Vincent C, Le Meur E, Six D and Thibert E (2007) Un service d’observation des glaciers des alpes franc¸aises «glacioclimalpes », pour quoi faire? Houille Blanche 3, 86–95 (doi: 10.1051/ lhb:2007040)

Vincent C, Soruco A, Six D and Le Meur E (2009) Glacier thickening and decay analysis from 50 years of glaciological observations performed on Glacier d’Argentie`re, Mont Blanc area, France. Ann. Glaciol., 50(50), 73–79 (doi: 10.3189/ 172756409787769500)

Willis IC (1995) Intra-annual variations in glacier motion: a review. Progr. Phys. Geogr., 19(1), 61–106

Zhang Y, Fujita K, Liu S, Liu Q and Wang X (2010) Multidecadal ice-velocity and elevation changes of a monsoonal maritime glacier: Hailuogou glacier, China. J. Glaciol., 56(195), 65–74

Zhang Y, Fujita K, Liu S, Liu Q and Nuimura T (2011) Distribution of debris thickness and its effect on ice melt at Hailuogou Glacier, southeastern Tibetan Plateau, using in situ surveys and ASTER imagery. J. Glaciol., 57(206), 1147–1157 (doi: 10.3189/ 002214311798843331)

Zumbu¨ hl HJ, Steiner D and Nussbaumer SU (2008) 19th century glacier representations and fluctuations in the central and western European Alps: an interdisciplinary approach. Global Planet. Change, 60(1–2), 42–57 (doi: 10.1016/j.gloplacha. 2006.08.005)

 


Europe

Alpine Space ClimChAlp ONERC
ONERC
Rhône-Alpes PARN

Portail Alpes-Climat-Risques   |   PARN 2007–2017   |  
Mentions légales