CPD Climate of the Past Discussions CPD Clim. Past Discuss. 1814-9359 Göttingen, Germany 10.5194/cp-2021-53 Tree-ring oxygen isotope based inferences on winter and summer moisture dynamics over the glacier valleys of Central Himalaya Singh Nilendu https://orcid.org/0000-0001-8624-8338 1 Shekhar Mayank 2 Parida Bikash Ranjan 3 Gupta Anil K. 4 Sain Kalachand https://orcid.org/0000-0001-8153-2997 1 Rai Santosh K. 1 Bräuning Achim 5 Sharma Vikram 6 Tiwari Reet Kamal https://orcid.org/0000-0002-3867-6036 7 Wadia Institute of Himalayan Geology, Dehradun 248001, India Birbal Sahni Institute of Palaeosciences, Lucknow 226007, India Dept. of Geoinformatics, School of Natural Resource Management, Central University of Jharkhand, Ranchi 835222, India Dept. of Geology and Geophysics, IIT Kharagpur, Kharagpur 721302, India Institute of Geography, University of Erlangen–Nuremberg, 91058 Erlangen, Germany Banaras Hindu University, Varanasi 221005, India Dept. of Civil Engineering, IIT Ropar 140001, India 28 05 2021 2021 1 24 Copyright: © 2021 Nilendu Singh et al. 2021 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://cp.copernicus.org/preprints/cp-2021-53/ The full text article is available as a PDF file from https://cp.copernicus.org/preprints/cp-2021-53/cp-2021-53.pdf

<p>Accelerated glacier mass loss is primarily attributed to greenhouse-induced warming, but land&ndash;climate interaction has increasingly been recognized as an important forcing at the regional-local scale. However, the related effects on the Himalayan glaciers are less explored but believed to be an important factor regulating spatial heterogeneity. This study aims to present a multi-decadal approximation on hydroclimate and glacier interaction over the western central Himalaya (WCH). Three highly coherent, multi-species, tree-ring &delta;<sup>18</sup>O site-chronologies from WCH were used to derive regional changes in atmospheric humidity (atmospheric moisture content: AMC) since the last four centuries. Coherency analyses between AMC and glacier mass balance (GMB: tree-ring &delta;<sup>13</sup>C-derived) indicate an abrupt phase-shift since the 1960s within a common record of 273 years. To ascertain the cause of phase-shift, annual AMC was disintegrated into seasonal-scale, utilizing &delta;<sup>18</sup>O record of deciduous species. Seasonal (winter: October&ndash;March; &amp; summer-accumulation season: April&ndash;September) decomposition results reveal that winter-westerlies rather than summer precipitation from Indian summer monsoon (ISM) govern the ice-mass variability in WCH. Decadal coherency between summer-season AMC and GMB remained relatively stable since the mid-20th century, despite a decline in central Himalayan summer precipitation (tree-ring &delta;<sup>18</sup>O records). We hypothesize that excess water vapor brought to the atmosphere through increase in pre-monsoon precipitation and greening-mediated increase in evapotranspiration might have been recycled through the summer season to compensate for the ISM part of precipitation. However, isotope-enabled ecophysiological models and measurements would be able to strengthen this hypothesis. In addition, high-resolution radiative forcing and glacier valley-scale vegetation trend analyses point towards a probable influence of greening on GMB. Results indicate that attribution of ice-mass to large-scale dynamics is likely to be modulated by local vegetation changes. We contend that glacier-climate models fed with these feedback processes could reliably improve the projections.</p>