SPECIAL SECTION: HIMALAYAN CRYOLOGY CURRENT SCIENCE, VOL. 114, NO. 4, 25 FEBRUARY 2018 760 *For correspondence. (e-mail: hs.negi@sase.drdo.in) Recent wintertime climatic variability over the North West Himalayan cryosphere H. S. Negi*, Neha Kanda, M. S. Shekhar and A. Ganju Snow and Avalanche Study Establishment, Him Parisar, Sector 37A, Chandigarh 160 036, India This study discusses the observed long-term (1991– 2015) and short-term (1991–2000 and 2001–2015) trends in winter temperature and precipitation over Northwestern Himalaya (NWH) along with its con- stituents, i.e. Lower Himalaya (LH), Greater Hima- laya (GH) and Karakoram Himalaya (KH). An overall warming signature was observed over NWH since maximum, minimum and mean temperatures followed rising trends with a total increase of 0.9C, 0.19C and 0.65C respectively, in 25 years, the increase being statistically significant for maximum and mean tem- peratures. However, warming was not consistent over all zones of NWH with minimum temperature at LH showing anomalous cooling by 0.83C (statistically significant at  = 0.05) during 25 years. The rise in mean temperature was observed highest at GH, i.e. 0.87C (1991–2015) followed by KH, i.e. 0.56C, which is in agreement with observations of comparatively higher rate of glacier retreat over GH than KH as reported in several studies. Total precipitation (rain- fall + snowfall) was found to increase whereas snow- fall was found to decrease with concurrent significant increase in rainfall at all zones of NWH. The spatio- temporal winter climatic variations over NWH sup- port the impact on recently reported findings on the Himalayan snow cover and glacier variations at dif- ferent durations. Keywords: Climate change, cryosphere, rainfall, winter warming and precipitation. Introduction MOUNTAINS cover almost 27% of the earth’s continental area 1 and support approximately 26% of total world population 2 . They play a vital role in regulating circula- tion patterns and thus shaping the weather over an area 3,4 . The mountains of the Himalaya are active in the regula- tion and redistribution of water resources as they contain headwater of many major rivers like the Ganges, Brahmaputra and Indus 5 . Some studies suggest that high- elevation environments comprising glaciers and perma- frost are among the most sensitive indicators of climate change 6,7 . Detailed study of climate change impacts on water resources of Asia is crucial since glacial melt run- off in the continent is expected to increase in near future, thereby prompting water scarcity in the longer run due to global warming 8 . However, many such studies are impeded by scarcity of ground-observed data due to remoteness of the region 9,10 . Several attempts to study the prevailing snow-meteoro- logical conditions over snow-bound areas of Northwestern Himalaya (NWH) utilizing ground-observed data report rise in temperature by various extents 11–14 , whereas excep- tional results conclude cooling over various parts of the Himalaya like Karakoram, Upper Indus Basin (UIB) and Western Himalayas during different seasons 12,15–18 . This spatially variable climate trend is attributed to significant altitudinal range of the Himalaya. Hence, distinct climatic zones similar to those separated by wide latitudinal belts can be observed within short horizontal distances 3 . Sharma and Ganju 19 also classified NWH into three distinct snow climatic zones, viz. lower, middle and upper Himalayan zones. Moderate temperature and high precipitation having significant impact on snow properties are the main charac- teristics of the lower Himalayan (LH) zone. The middle Himalayan zone encompassing the Greater Himalaya (GH) has numerous glaciers and is characterized by cold tem- perature with precipitation usually in the form of dry snow. The upper Himalayan zone which includes the Karakoram Himalayan (KH) range is characterized by extreme cold temperature with much of the area occupied by large glacial masses. Precipitation is in the form of dry snow with fewer events of rainfall during summer, that too in the valley region 20 . The impact of global warming on the cryosphere is evident worldwide. It has been reported that the Himala- yan glaciers are receding in most of the regions 21,22 , except a few glaciers of Karakoram which display het- erogeneity 23,24 . In addition, mass balance study of the Himalayan glaciers depicts loss in mass, i.e. negative mass balance 21,25,26 , except slight mass gain reported from a few glaciers of KH 27,28 . The spatially variable response of glaciers in the Himalaya is attributed to climate and topography of the region, since it was reported that gla- ciers lying in the westerly influenced areas have either advanced or show stability, while debris covered glaciers are found to have stable fronts. On the contrary, those in- fluenced by summer monsoon are unstable and retreat rates are very high for such glaciers 10 . The varying extent of snow cover area (SCA) over the Himalaya using satel- lite data has also been reported for different durations and