High-elevation shrub-ring delta O-18 on the northern slope of the central Himalayas records summer (May-July) temperatures

摘要

The potential of shrub-ring oxygen isotopes (SRO) as a paleoclimatic proxy is not well demonstrated. In this study we explored the climate signals embedded in an SRO chronology from Saga, on the northern slope of the central Himalayas by correlation analysis with climate variables and comparison with tree-ring and/or ice-core delta O-18 records. The Saga SRO had significant and positive correlations with May-July temperatures in both local (r = 0.43) and moisture source areas (r = 0.49) during the period 1955-2015 (CE), while no significant correlations were found with hydroclimatic variables. It is also in good agreement with two tree-ring delta O-18 series from the southern slope of the central Himalayas, the source of moisture to the site. The temperature signals are further verified by an ice core delta O-18 record from the Tanggula Mountains on the central Tibetan Plateau. However, it shows little similarity with the nearest Himalayan ice core delta O-18 record from Dasuopu, demonstrating temperature signals of different seasons. This study suggests that SRO could be used as an acceptable climate proxy, like tree-ring and ice-core delta O-18, to broaden the spatial extent of the paleoclimatic records network. However, we should be cautious when combining different proxies with climate signals of different seasons in paleoclimate studies.