Decadal evolution of a very small heavily debris-covered glacier in an Alpine permafrost environment

M. CAPT,N. MICHELETTI,M. FISCHER,J.-B. BOSSON,C. LAMBIEL

doi:10.1017/jog.2016.56

M. CAPT, N. MICHELETTI + Show 3 more

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https://doi.org/10.1017/jog.2016.56

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Abstract

AbstractGlacier response to climate forcing can be heterogeneous and complex, depending on glacier system characteristics. This article presents the decadal evolution of the Tsarmine Glacier (Swiss Alps), a very small and heavily debris-covered cirque glacier located in the Alpine periglacial belt. Archival aerial photogrammetry and autocorrelation of orthophotos were used to compute surface elevation, volume and geodetic mass changes, as well as horizontal displacement rates for several periods between 1967 and 2012. A GPR survey allowed us to investigate glacier thickness (15 m mean) and volume (4 × 106m3) in 2015 and to anticipate its future evolution. Different dynamics occurred in recent decades because of the heterogeneous surface characteristics. The climate-sensitive upper debris-free zone contrasts with the progressively stagnant heavily debris-covered glacier tongue. Between 1967 and 2012, the glacier lost 1/3 of its initial volume (2 × 106m3). The average mass balance stabilised at ~−0.3 m w.e. a−1since 1999. Compared with other local glaciers, the Tsarmine Glacier shows a particular decadal behaviour both in time (divergence of mass balance since the 2000s) and space (inverted ablation pattern). This might be explained by the combined influence of debris cover, shadow, snow redistribution and permafrost conditions on this very small glacier.

Highlights

Knowledge about the global response of the >200 000 glaciers on Earth to climate change has considerably improved in recent years (Vaughan and others, 2013; Pfeffer and others, 2014), especially through large-scale modelling (e.g. Gardner and others, 2013; Radić and others, 2014; Huss and Hock, 2015)
Large uncertainties remain for individual glaciers because processes and glacial dynamics are implemented in a simplified manner in the models
Supraglacial debris covers are expanding on mountain glaciers (Carturan and others, 2013a; Kirkbride and Deline, 2013)

Summary

Introduction

Knowledge about the global response of the >200 000 glaciers on Earth to climate change has considerably improved in recent years (Vaughan and others, 2013; Pfeffer and others, 2014), especially through large-scale modelling (e.g. Gardner and others, 2013; Radić and others, 2014; Huss and Hock, 2015). Each glacier shows specific behaviour to some extent, influenced by local topoclimatic factors, glacier hypsometry or surface characteristics (Carturan and others, 2013a; Fischer and others, 2015) These particularities may generate non-linearities that complicate the response of glaciers to climate change (Paul and others, 2007; Scherler and others, 2011; Carrivick and others, 2015). In high-relief environments, three characteristics can strongly influence the individual response of glaciers to climatic variations: (1) small glacier size, (2) debris cover on the ice and (3) permafrost conditions. These characteristics affect an increasing number of mountain glaciers with the current rise in the ELA (Benn and others, 2003; Vaughan and others, 2013). Supraglacial debris covers are expanding on mountain glaciers (Carturan and others, 2013a; Kirkbride and Deline, 2013)

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