Climate Change and Cryospheric Response Over North-West and Central Himalaya, India

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This study summarizes the results of several climate studies conducted using field observed data of winter period over the North-West Himalaya (NWH) and Central Himalaya (CH). It also summarizes the latest conclusions about wintertime trends over NWH and its constitutive zones that have been drawn from the study conducted by Negi et al. (Curr Sci 114(4):760–770, 2018), which incorporates the results and inferences of all other studies as well. Wintertime climatic variability over CH has also been discussed for the first time in this study. The salient deductions are as under: Overall warming trends in mean and maximum temperature of NWH (1991–2015) and CH (2001–2012) have been observed. In contrast to the situation at the global scale, the data of both NWH and CH reflect higher rate of warming in maximum temperature than minimum temperature. Consequently, there has been an increase in Diurnal Temperature Range (DTR) over both NWH and CH. Regionally, long term (~30 years) warming trends have been observed in all zones of NWH except for the minimum temperature over the Lower Himalaya (LH) which shows cooling trends. The rate of warming (mean temperature) is found to be highest in the Greater Himalaya (GH) than the Karakoram Himalaya (KH) and LH, which partly explains the higher rate of glacier melt in regions of GH than KH. In addition, no conclusive trends in Elevation Dependent Warming (EDW) were observed in NWH. Short term trends (2000–2015) depict cooling in maximum temperature of LH and GH, which though unexplained, may have some links with rising concentration of aerosols in atmosphere in recent decades as reported in a study by Krishnan and Ramanathan (Geophys Res Lett 29(9):54–1–54–4, 2002). The cryosphere of NWH and CH show heterogeneous behaviour to climate change. Long term warming trends over LH, GH and CH have manifested in retreat of glaciers lying in these areas. Though KH also reports warming but this marginal increase in temperature field has not yet made a dent in KH where temperatures are still in subfreezing range even during ablation period. This obviously has resulted in less ablation indirectly implying marginal gain in mass, which has resulted in bringing more stability to the glaciated region of Karakoram Himalaya.