Time dependent assessment of glacier recession in the Indian Central Himalaya

In recent decades, the Himalayan cryosphere has been subject to significant changes as a consequence of regional climate warming. The glaciers within the Indian Central Himalayas are vital to the maintenance of the major river systems of South Asia and are sensitive indicators of climate change. Various studies have reported considerable glacier recession, thinning, and mass loss within the region, though the extent and velocity of change vary considerably among glaciers because of climatic and topographic conditions. This review has been conducted with meticulous attention to compile considerable field observations and satellite data obtained over several decades to understand the temporal dynamics of glaciers within the Indian Central Himalayas of Uttarakhand State. The current study has been conducted to understand the changes in glacier length, terminus retreat, changes in mass balance, and changes in ELA as reported within earlier studies conducted within the region. The findings of the current study report considerable spatial variability within glaciers, with the velocity of frontal retreat ranging from a few meters per annum within debris-covered glaciers to over 80 m per annum within clean-ice glaciers that exhibit rapid recession. Recent research findings have shown a marked increase in ELA values as well as a trend of increasingly negative mass balance conditions. While climate change and alterations in precipitation patterns are the primary factors responsible for the recession of glaciers, various non-climatic factors such as the geometry of the glacier, the slope of the terrain, the aspect of the terrain, as well as the presence of supraglacial debris cover, also assume a vital role. The review provides a comprehensive overview of decades-long observations in the field along with satellite-based studies on the spatial and temporal aspects of glacier retreat in the Indian Central Himalayan region. The review attempts to bring together information on glaciers in particular and regional climate change trends in general, highlighting aspects such as atmospheric warming, glacier morphometry, and supraglacial debris cover in relation to glacier retreat, while highlighting gaps in knowledge on glaciers.