Research Projects

Understanding temperature and precipitation variations in the Himalayan region is crucial for ensuring the annual water supply to millions of people. Tree rings are excellent archives for understanding climate variability before the instrumental era and the effect of current climate change. However, only a few isotope-based investigations exist in the Himalayan region. Initial investigations have revealed that the response of oxygen isotopic composition (d¹⁸O) of tree rings to the concurrent climate depends on the location in the Himalayas. Chronologies from monsoon shadow regions respond mainly to winter precipitation and their response to summer temperature is subdued. Tree-ring d¹⁸O chronologies from regions receiving sufficient monsoonal rainfall are influenced by summer temperature and precipitation. Correlations of annual tree-ring d¹⁸O values with monthly climatic parameters have been extensively used to decipher the climate signal in the tree rings. Understanding the processes beginning from the root zone to the synthesis of cellulose is crucial in climate reconstruction. Winter snow and summer rains are two prominent sources of soil moisture in the western Himalayas, but the extent of these moisture sources' influence on d¹⁸O of tree rings is not known. The project proposes studying two aspects of isotope dendroclimatology: characterization of the isotopic composition of tree rings as a climate proxy and reconstructing the relative strengths of monsoon and westerlies.