Deciphering Climate Variability Over Western Himalaya Using Instrumental And Tree-Ring Records

In this chapter, we discuss climate variability over the Western Himalaya based on instrumental records as well as information derived from tree-ring data. We focus here on two important climatological elements, namely rainfall and temperature of Western Himalayan region. Trend analyses of rainfall based on 14 stations covering entire western Himalayan region from Kashmir to Uttarakhanda indicate different patterns of rainfall variability. The database does not show any coherent patterns among the stations and does not indicate any significant trend during the twentieth century. Data on temperature show overall warming mainly contributed by maximum temperature. Most of the stations indicate significant increasing trends in maximum temperature for all the seasons. Cooling trend is observed mostly in minimum temperature of some stations for different seasons. Annual maximum, minimum and mean temperature series of all the stations indicate significant warming except slight cooling in minimum temperature of Deheradun, Mukteswar and Mussoorie. Climate projections for twenty-first century also indicate warming over the entire Himalayan region with significant warming in Tibetan plateau, and increasing trend in summer precipitation over the central Himalayan region including Nepal and Tibetan Plateau.Dendroclimatic reconstructions give some information about summer climate conditions since past several centuries. They indicate some cool epochs associated with Little Ice Age (LIA). It is also seen that high altitude near glacier tree-ring records would be the potential source of information on long-term temperature variability and glacier fluctuations. Overall warming trends noted in different parts of the western Himalaya may be linked partially to global warming trends and rapid urbanization of the hill stations were the observatories are located.