From balance to imbalance: a shift in the dynamic behaviour of Chhota Shigri glacier, western Himalaya, India
Résumé
Mass-balance and dynamic behaviour of Chhota Shigri Glacier have been investigated between 2002 and 2010 and compared to data collected in 1987/1989. During the period 2002/2010, the glacier experienced a negative glacier-wide mass balance of -0.67 ± 0.40 m/a w.e. Between 2003 and 2010, elevation and ice flow velocities are slowly decreasing in the ablation area leading to a 24 to 37% reduction in ice fluxes, an expected response of the glacier dynamics to its recent negative mass balances. The reduced ice fluxes still remain far larger than the balance fluxes calculated from the year 2002 to 2010 average surface mass balances. Therefore, further slow down, thinning and terminus retreat of Chhota Shigri Glacier are expected over the next years. Conversely, the 2003/2004 ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987/1989 and 2003/2004 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers of Western Himalaya have been shrinking rapidly for the last decades.
Domaines
Océanographie
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