Central Himalayan tree-ring isotopes reveal increasing regional heterogeneity and enhancement in ice-mass loss since the 1960s
Tree-ring δ 18 O values are a sensitive proxy of regional physical climate, while their δ 13 C values are a strong predictor of local ecohydrology. Utilizing available ice-core and tree-ring δ 18 O records from central Himalaya (CH), we show an increase in east-west heterogeneity since the 1960s. Fu...
| Main Authors: | , , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/tc-2020-128 https://tc.copernicus.org/preprints/tc-2020-128/ |
| Summary: | Tree-ring δ 18 O values are a sensitive proxy of regional physical climate, while their δ 13 C values are a strong predictor of local ecohydrology. Utilizing available ice-core and tree-ring δ 18 O records from central Himalaya (CH), we show an increase in east-west heterogeneity since the 1960s. Further, δ 13 C records from transitional western glacier valleys provide a robust basis of reconstruction of about three centuries of glacier mass balance (GMB) dynamics. Annually resolved GMB is based on regionally-dominant and diverse plant-functional species since the 1743 CE. Results indicate three major phases: positive GMB up to the mid-nineteenth century, the middle phase of slightly negative but stable GMB, and an exponential ice-mass loss since the 1960s. Reasons of accelerated mass loss are largely attributed to anthropogenic climate change, including concurrent alterations in atmospheric circulations (weakening of the westerlies and Arabian Branch of the Indian summer monsoon). CH-scale, multi-decadal isotopic and climate coherency analyses specify an eastward declining influence of westerlies in this monsoon-dominated region. Besides, our study provides a long-term context for recent GMB variability, which is essential for reliable projection and attribution. |
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