Balanced conditions or slight mass gain of glaciers in the Lahaul and Spiti region (northern India, Himalaya) during the nineties preceded recent mass loss

The volume change of the Chhota Shigri Glacier (India, 32 degree 20 N, 77 degree 30' E) between 1988 and 2010 has been determined using in situ geodetic measurements. This glacier has experienced only a slight mass loss between 1988 and 2010 (-3.8 plus or minus 2.0 m w.e. (water equivalent) corresponding to -0.17 plus or minus 0.09 m w.e. yr super(-1)). Using satellite digital elevation models (DEM) differencing and field measurements, we measure a negative mass balance (MB) between 1999 and 2010 (-4.8 plus or minus 1.8 m w.e. corresponding to -0.44 plus or minus 0.16 m w.e. yr super(-1)). Thus, we deduce a slightly positive or near-zero MB between 1988 and 1999 (+1.0 plus or minus 2.7 m w.e. corresponding to +0.09 plus or minus 0.24 m w.e. yr super(-1)). Furthermore, satellite DEM differencing reveals that the MB of the Chhota Shigri Glacier (-0.39 plus or minus 0.15 m w.e. yr super(-1)) has been only slightly less negative than the MB of a 2110 km super(2) glaciarized area in the Lahaul and Spiti region (-0.44 plus or minus 0.09 m w.e. yr super(-1)) during 1999-2011. Hence, we conclude that the ice wastage is probably moderate in this region over the last 22 yr, with near equilibrium conditions during the nineties, and an ice mass loss after. The turning point from balanced to negative mass budget is not known but lies probably in the late nineties and at the latest in 1999. This positive or near-zero MB for Chhota Shigri Glacier (and probably for the surrounding glaciers of the Lahaul and Spiti region) during at least part of the 1990s contrasts with a recent compilation of MB data in the Himalayan range that indicated ice wastage since 1975. However, in agreement with this compilation, we confirm more negative balances since the beginning of the 21st century.