Réf. Farinotti & al. 2009 - A

Référence bibliographique complète

FARINOTTI, D., HUSS, M., BAUDER, A., FUNK, M. 2009. An estimate of the glacier ice volume in the Swiss Alps. Global and Planetary Change, 68, 225–231.

Abstract: Changes in glacier volume are important for questions linked to sea-level rise, water resource management, and tourism industry. With the ongoing climate warming, the retreat of mountain glaciers is a major concern. Predictions of glacier changes, necessarily need the present ice volume as initial condition, and for transient modelling, the ice thickness distribution has to be known. In this paper, a method based on mass conservation and principles of ice flow dynamics is applied to 62 glaciers located in the Swiss Alps for estimating their ice thickness distribution. All available direct ice thickness measurements are integrated. The ice volumes are referenced to the year 1999 by means of a mass balance time series. The results are used to calibrate a volume–area scaling relation, and the coefficients obtained show good agreement with values reported in the literature. We estimate the total ice volume present in the Swiss Alps in the year 1999 to be 74±9 km3. About 12% of this volume was lost between 1999 and 2008, whereas the extraordinarily warm summer 2003 caused a volume loss of about 3.5%.

Mots-clés
Ice volume, Ice thickness, Volume–area scaling, Radio-echo sounding, Swiss Alps

Organismes / Contact

Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, CH-8092 Zurich, Switzerland - farinotti@vaw.baug.ethz.ch


(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
Temperature Glaciers    

Pays / Zone
Massif / Secteur
Site(s) d'étude
Exposition
Altitude
Période(s) d'observation
Switzerland   All Swiss glaciers     1999-2008

(1) - Modifications des paramètres atmosphériques
Reconstitutions
 
Observations
 
Modélisations

Warming of the climate system is unequivocal (Solomon et al., 2007) and for the Swiss Alps, a further temperature increase of 1.8 °C in winter and 2.7 °C in summer has been projected until the year 2050 (Frei, 2007).

Hypothèses
 

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

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

The authors estimate the total glacier ice volume present in the Swiss Alps in 1999 to be 74±9 km3. This corresponds to a mean ice thickness of 70±8 m. About 88% of the volume (65±5 km3) is stored in the 59 largest glaciers (glaciers with a surface area A≥3 km²). The glacier sample analyzed with the empirical volume–area scaling relation (glaciers with A<3 km²) contributes with 33% to the total surface area and contains 12% of the total volume. For 6 of the 10 largest glaciers, which contribute together to more than half of the total estimated ice volume, direct ice thickness measurements were available to determine the ice volume. This causes, together with the assumption of normally distributed uncertainties in the individual ice volumes, the confidence interval of the total ice volume to become relatively small (12%), even though significantly larger uncertainties are assessed for individual glaciers.

The mass balance time series allows the total glacier ice volume calculated for the Swiss Alps to be put in context of climate change. The authors estimate that in the time span 1999–2008, the total ice volume has decreased by about 12%. Due to the assumption of a constant glacier area in this time interval, the value has to be considered as an upper boundary. The volume loss occurring during the particularly warm year 2003 (b = −2.40 m w.e.) is estimated as about 3.5% of the total glacier ice volume of the Swiss Alps, corresponding to 2.6 km3 of ice.

Modélisations
 
Hypothèses
 

Sensibilité du milieu à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)

Warming of the climate system is unequivocal and for the Swiss Alps, a further temperature increase of 1.8 °C in winter and 2.7 °C in summer has been projected until the year 2050 [see references above]. This causes major concern about the (partial) disappearance of alpine glaciers (e.g. Zemp et al., 2006; Huss et al., 2008b).

When assessing future glacier retreat, the current ice volume is the most important initial condition. In general, this information is available for a small number of glaciers onlyand is linkedwithmajor uncertainties. For transient glaciermodelling, supplementary information about the ice thickness distribution is required. Obtaining this information is difficult, as direct measurement techniques, such as radio-echo soundings or borehole measurements, are laborious, necessarily restricted to a limited area, and the spatial inter- and extrapolation of the field datamay lead to large uncertainties. For glaciers without direct ice thickness measurements, the total ice volume is often estimated with empirical relations between glacier area and volume (e.g. Erasov, 1968; Bahr et al., 1997) or glacier area and mean ice thickness (e.g. Müller et al., 1976).

Recently, Farinotti et al. (2009) proposed a method based on mass conservation and principles of ice flow dynamics to estimate the ice thickness distribution of alpine glaciers from surface topography. In the current paper, the authors apply this method (here referred to as ITEM for Ice Thickness Estimation Method) and present an updated estimate of the total glacier ice volume of the Swiss Alps referenced to the year 1999. All available direct ice thickness measurements are integrated, none of them available for any of the previously mentioned studies addressing the ice volume in the Alps. Particular attention is focussed on assessing the uncertainty in the results. The volume estimation is carried out by applying (1) ITEM to all glaciers of the Swiss Alps with a surface area larger than 3 km² (59 glaciers in 1999) and some smaller selected glaciers for which ice thickness measurements are available (3 glaciers), and (2) an empirical volume–area scaling relation as proposed by Bahr et al. (1997) to glaciers smaller than 3 km². The sample of glaciers analyzed using ITEM covers 67% of the total glacierized area. For these glaciers a complete glacier bedrock topography is generated on a 25 m grid, which, together with a surface elevation model, provides the ice thickness distribution. [see details in the study]


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

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

 


(4) - Remarques générales

The glacier retreat in the Swiss Alps since the end of the Little Ice Age (around 1850) is well documented (e.g. Glaciological Reports, 1881–2008; Müller et al., 1976; Maisch et al., 2000), and several studies provide projections for its future evolution (e.g. Schneeberger et al., 2003; Huss et al., 2007). Estimates of the total ice volume in the Swiss Alps, however, are scarce and based on the Swiss Glacier Inventory 1973 (SGI1973) by Müller et al. (1976) exclusively. Using two different empirical relations between glacier area and mean ice thickness, Müller et al. (1976) and (Maisch et al. (2000) estimated the total ice volume of the Swiss Alps in 1973 to be 67 km3 and 74 km3, respectively.

A few more estimates exist for the total ice volume of the entire (not only the Swiss) Alps. Haeberli and Hoelzle (1995) applied a parametrization scheme based on vertical glacier extent, glacier length and glacier area to estimate the total ice volume around 1970 to be about 130 km3. Putting this value into context with the Swiss ice volume is not straightforward, since the size distribution of glaciers in the European Alps is different from that one in the Swiss Alps.


(5) - Syntèses et préconisations
 

Références citées :

Bahr, D.B., Meier, M.F., Peckham, S.D., 1997. The physical basis of glacier volume–area scaling. Journal of Geophysical Research 102 (B9), 20355–20362.

Erasov, N.V., 1968. Method to determine the volume of mountain glaciers. Materialy Glyatsiologicheskikh Issledovanii: Khronika, Obsuzhdeniya, vol. 14.

Farinotti, D., Huss, M., Bauder, A., Funk, M., Truffer, M., 2009. A method to estimate ice volume and ice thickness distribution of alpine glaciers. Journal of Glaciology 55 (191), 422–430.

Frei, C., 2007. Climate change and Switzerland 2050 — impacts on environment, society and economy. Advisory Body on Climate Change (OcCC), pp. 12–16. http://www. occc.ch.

Glaciological Reports (1881–2008). The Swiss Glaciers, 1880–2002/03. Yearbooks of the Cryospheric Commission of the Swiss Academy of Sciences (SCNAT), No. 1–124. published since 1964 by Laboratory of Hydraulics, Hydrology and Glaciology (VAW) of ETH Zürich, http://glaciology.ethz.ch/swiss-glaciers/.

Haeberli, W., Hoelzle, M., 1995. Application of inventory data for estimating characteristics of and regional climate-change effects on mountain glaciers: a pilot study with the European Alps. Annals of Glaciology 21, 206–212.

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

Huss, M., Bauder, A., Funk, M., Hock, R., 2008a. Determination of the seasonal mass balance of four Alpine glaciers since 1865. Journal of Geophysical Research 113, F01015.

Huss, M., Farinotti, D., Bauder, A., Funk, M., 2008b. Modelling runoff from highly glacierized alpine catchment basins in a changing climate. Hydrological Processes 3888–3902. doi:10.1002/hyp.7055.

Huss, M., Bauder, A., Funk, M., 2009. Homogenization of long-term mass balance time series. Annals of Glaciology 50, 198–206.

Maisch, M., Wipf, A., Denneler, B., Battaglia, J., Benz, C., 2000. Die Gletscher der Schweizer Alpen. vdf Hochschulverlag AG an der ETH Zürich, Zürich. Schlussbericht NFP31.

Müller, F., Caflisch, T., Müller, G., 1976. Firn und Eis der Schweizer Alpen: Gletscherinventar. Publ. Nr. 57. Geographisches Institut der ETH Zürich, Zürich.

Schneeberger, C., Blatter, H., Abe-Ouchi, A., Wild, M., 2003. Modelling changes in the mass balance of glaciers of the northern hemisphere for a transient 2×CO2 scenario. Journal of Hydrology 282 (1–4), 145–163.

Solomon, S., et al., 2007. Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. InCambridge University Press.

Zemp, M., Haeberli, W., Hoelzle, M., Paul, F., 2006. Alpine glaciers to disappear within decades? Geophysical Research Letters 33 (13), L13504. [Fiche biblio]