Gravity and Geodetic Studies in India : Historical Observations and Advances During the Past Decade

Abstract

The present review takes stock of the growth of crysospheric research in India with reference to glaciers and snow in the Himalaya, which are sensitive marker of the climate change. Overview of the snout and mass balance data indicates accentuated rate of glacier recession during the 1970's and 1980's, particularly in the Central and NE Himalaya. Like elsewhere on the globe, the retreating trends are consistent with the hypothesis of the global warming resulting from the increasing anthropogenic emissions of Green Houses Gasses. In contrast, the Glaciers in the Karakoram region, Indus basin, fed by mid-latitude westerlies, show marginal advancement and/or near stagnation. The climatic influence of temperature and precipitation (monsoon-vis-a-vis-westerlies) combine in complex manner to produce heterogeneous spatial or temporal variations in glaciers, including the slow-down in glacier retreat since 1990's all along the Himalayan arc. From continuously growing monitoring, it is apparent that beside the precipitation and temperature, geometry (wide and narrow), orientation (north or south phasing) of glacier, altitude distribution in accumulation/ablation zones, debris cover, lithology of rock types, process of erosion/weathering, atmospheric chemistry (black carbon) control the variability in glacier mass and hydrology. Quantification of various forcing parameters to allow their use in prediction of melt water contribution to perennial rivers is an important area of future research. Road map of future glacier-climate-hydrology studies, on the lines of ongoing studies in Antarctica-Arctic, is drawn with strong recommendations to establish National Institute of Glaciology.