February–March minimum temperature record from cold-arid Lahaul-Spiti, Himachal Pradesh, India, and its hydrological implications

The increasing number of climate-associated disasters in the Himalayan region causing a huge impact on human life and the ecosystem are the bellwethers of climate change. Weather records from the high Himalayas, though sparse and limited to the past few decades, show its sensitivity to global climate change. However, short observational records preclude our understanding of long-term climate variation over the topographically controlled Himalaya. In view of this, tree-ring data of Himalayan birch trees from the cold-arid Lahaul-Spiti, Himachal Pradesh, western Himalaya is analyzed in the present study. The response function analysis of Himalayan birch chronologies with climate variables revealed a significant impact of February–March minimum temperature in radial growth of Himalayan birch. Taking this relationship as a guide, we developed the first record of winter/spring (February–March) minimum temperature for this region. The reconstructed minimum temperature record reveals annual to decadal scale variability associated with several prolonged cold and warm periods. A strong association of warm/cold phases of February–March temperature with low/high snow water equivalent of western Himalaya, as well as seasonal snow and glacial derived streamflow of the upper Indus River basin was identified. The observed hydrological linkages were further tested using river flow records of the Satluj and Indus Rivers of the western Himalaya. The observed opposite relationship between winter–spring minimum temperature and the summer hydro-climatic records can be of immense use to policymakers, agriculture stockholders, and hydropower project officials to take precautionary measures in advance.