RESUMEN
This study aims to assess the glaciers change status in Shyok basin, East Karakoram in terms of area and mass balance, and to ascertain if glaciers in this part of Karakoram also display similar anomaly like central or western counterparts. The spatio-temporal monitoring of glaciers during the time frame of 24 years (1990/2000/2014) suggests major percentage of stable glaciers and insignificant retreat in the total glaciated area. The percentage of retreating glaciers has increased after year 2000. Area change analysis of glaciers having size >1 km2 (569 glaciers) suggests the number of fluctuated glaciers have substantially increased i.e. overall 56% glaciers remained stable, 35% retreated and 9% advanced during 1990-2014. The geodetic based findings using SRTM-C (2000) and Cartosat-1 (2010/2011/2014) stereo-imageries for 201 glaciers suggest the mass loss at the rate of -0.10 ± 0.07 m w.e. a-1. To better apprehend the status of glaciers changes in the region, climatic studies using in-situ observations as well as reanalysis dataset (ERA-I) were also undertaken of past 30 years. Therefore, this study is also a maiden attempt to ascertain if along with Karakoram anomaly, a climatic anomaly exists in the Eastern parts of Karakoram or not. A long term field collected snow-meteorological data of East Karakoram region suggests overall warming trend in annual temperature and no trend for snowfall during 1985-2015. The statistically significant increased rates of warming and decreased snowfall after year 2000 support the spatial variations in glaciers of East Karakoram and marginal mass loss. The observations of the marginal mass loss along with warming temperatures indicate that no Karakoram or climatic anomaly is existent over the East Karakoram region. Our study further refutes the prevalence of the elevation-dependent warming (EDW) over East Karakoram region vis-à-vis North-West Himalayan ranges. The impact of hiatus in global warming was also not observed over studied region.
RESUMEN
Located in the eastern lap of the Karakoram Range, the Siachen Glacier is the second longest glacier in the non-polar areas of the world. High altitude, extreme climate and frequent military conflicts on this glacier create antagonistic surroundings for conventional field studies. Although recent advancements in geodetic technique have helped in the estimation of Siachen mass budget (MB), these geodetic estimates have been observed only for short time periods ranging 6 to 10 years. Hence, current study presents a comprehensive assessment of the Siachen long-term MB (32 years) based on temperature index (TI) model. Annual surface MB variability was modelled between 1986 and 2018 by forcing daily air temperature and precipitation from multiple ground stations distributed well across accumulation/ablation zone of the glacier. Mean annual temperature lapse rate (LR) was found midway between dry adiabatic and moist adiabatic LRs. Precipitation gradient (PG) was observed remarkably different below and above 4800 m.a.s.l. glacier altitude. Furthermore, snowmelt factor (SMF) was also estimated using snow thickness and positive degree days (PDDs) information over the glacier surface. Model results showed a nearly balanced condition (- 0.02 ± 0.05 m.w.e./year) during 1986-2006 followed by an accelerated rate of mass loss during 2007-2018 (- 0.11 ± 0.05 m.w.e./year), thus making the overall condition of Siachen MB negative during the period 1986-2018 (- 0.05 ± 0.05 m.w.e./year). Comparison of modelled MB was made with few geodetic studies conducted for the Siachen Glacier at different time scales (mainly after year 2000). Further, the sensitivity of the modelled glacier-wide MB was - 0.24 m.w.e./year for a temperature rise by 1 °C, while the sensitivity towards 10% increase in precipitation was estimated to be + 0.16 m.w.e./year. A relationship of the annual MB with accumulation area ratio (AAR) and equilibrium line altitude (ELA) was also established for Siachen glacier.