Tree ring oxygen isotope (δ¹⁸O) variations from western Himalaya and it linkage with vapor pressure and runoff water in India

A 242-year regional oxygen isotope (δ¹⁸O) ratio has been prepared based on distinct oxygen isotopes collected from different species from different locations of the western Himalayas for a better understanding of climate fluctuations. The strongest negative correlation coefficient (-0.40) of δ¹⁸O was observed with runoff during 1902–2006. The result indicates that δ¹⁸O is controlled by runoff water from June-August. Increasing/decreasing runoff over the region may be in favour for decreasing/increasing the oxygen isotope. Whereas Vapor pressure shows a positive correlation (0.38) with δ¹⁸O from June to August across the western Himalayas. The positive relationship of δ¹⁸O with vapor pressure indicates that warmer conditions over the region may enhance the evaporation from soil moisture increasing δ¹⁸O in the water. It means that increasing/decreasing temperature might be associated with increasing/decreasing oxygen isotope (δ¹⁸O) ratio in tree ring cellulose. The correlation coefficient of temperature and vapor pressure with runoff water is -0.41 and − 0.35. Both are statistically significant at 0.1% level.