A shallow ice core re-drilled on the Dunde Ice Cap, western China: recent changes in the Asian high mountains

Abstract

A 51 m deep ice core was re-drilled on the Dunde Ice Cap of western China in 2002, 15 years after the previous ice core drilling in 1987. Dating by seasonal variations in δ 18 O and particle concentration showed that this 51 m deep ice core covered approximately the last 150 years. The stratigraphy and density showed that more than 90% of the ice core was refrozen ice layers, which comprised less than 5% of the annual accumulation in the older core. This indicates that the ice cap had experienced a more intense melting since 1987, possibly due to climate warming in this region. Mean net accumulation since the last drilling was 176 mm a −1 , which was considerably smaller than that obtained from the 1987 core (390 mm a −1 , 1987-1963), indicating a significant decrease of net accumulation on the ice cap in the more recent period. The δ 18 O record showed an increasing trend in the late 19th century and the highest in the 1950s, which is consistent with the previous core findings. However, there has been no significant increase in δ 18 O during the last two decades, in contrast to the warming trends suggested by the melt features and other climate records. This discrepancy may be due to the modification of δ 18 O records by melt water runoff, percolation, and refreezing on the ice cap. Results strongly suggest recent significant mass loss of glaciers in the Asian high mountains and serious shortage of water supply for local people in this arid region in the near future.

Changes of the Bacterial Abundance and Communities in Shallow Ice Cores from Dunde and Muztagata Glaciers, Western China

“…A Finnegan MAT-252 mass-spectrometer was used to determine δ 18 O values within ± 0.05%. The Dunde ice core was dated by using seasonal δ 18 O variations and annual visible dust layers and confirmed by the previous data (Takeuchi et al, 2009). The Muztagata ice core dating and δ 18 O data were previously described by Tian et al (2006).…”

“…The δ 18 O value was measured by Finnegan MAT-252 gas stable isotope ratio mass-spectrometer. In this study, the ice core section at 0.54–9.81 m depth was dated by using seasonal δ 18 O variations and annual visible dust layers, and confirmed by the 51-m-long Dunde ice core drilled at the same site and in the same year 2002 (Takeuchi et al, 2009). The winter-spring seasons of 1992 and 2000 were identified and confirmed by the deep valleys of δ 18 O and dust peaks, the summer of 1989 was identified by the peak of δ 18 O, and the summer of 1985 was confirmed by both of the δ 18 O and dust peaks, respectively.…”

Twentieth century dust lows and the weakening of the westerly winds over the Tibetan Plateau

“…To assess the extent of the GL dust proxy record, comparisons were made to contemporary ice core dust proxy records on the TP (Dunde [ Takeuchi et al ., ; Yang et al ., ], Malan [ Wang et al ., ], and Puruogangri [ Thompson et al ., ]), and in the Himalayas (i.e., Everest [ Kaspari et al ., ] and Dasuopu [ Thompson et al ., ]) (Figure a). TP dust proxies display distinct similarities to GL, including the lowest concentrations occurring between 1950 and 1980 (the only exception being two low dust periods (late 1500s and late 1600s) at Malan).…”

“…Central Asia contains some of the Northern Hemisphere's largest sources of dust and is estimated to emit 10–30% of global emissions [ Tanaka and Chiba , ; Miller et al ., ; Werner et al ., ] (see supporting information Text S1). The Central Asian Mountain System, which include the Pamirs, Hindu Kush, Tien Shan, Altai, the Himalayas, and the Tibetan Plateau (TP), provide excellent locations for reconstructing past atmospheric dust as it contains high‐elevation glaciers that hold well‐preserved ice core records [e.g., Aizen et al ., ; Kang et al ., ; Kaspari et al ., ; Mayewski et al ., ; Takeuchi et al ., ; Thompson et al ., ]. Herein we present a high‐resolution, annually dated proxy record of atmospheric dust from a Mount Geladaindong (GL) ice core and investigate the variability and climatic controls of atmospheric dust on the TP over the last ~500 years.…”

Deuterium excess record in a southern Tibetan ice core and its potential climatic implications

“…The isotopic compositions in modern precipitation showed significant spatial and temporal variations because of the complex topography and the seasonally different sources of moisture forming precipitation on the TP (Tian et al 2001a;Yu et al 2007;Hren et al 2009). However, although much attention has long been paid to the d 18 O in precipitation on the TP, only recently has there been significant effort to understand the changes of d in modern precipitation on the TP (Tian et al 2001b;Kang et al 2002;Yu et al 2007;Liu et al 2008), and the record of d time series from ice core is more limited so far (Thompson et al 2000;Takeuchi et al 2009). The stable isotopic compositions in Tibetan ice cores are usually interpreted as reflecting regional temperature or precipitation amount over the regional area (Wang et al 2003;Joswiak et al 2010).…”