Temperature and methane records over the last 2 ka in Dasuopu ice core

High resolutionδ^(18)O and methane records over the last 2ka have been reconstructed from Dasuopu ice core recovered from the Himalayas.Analysis shows that theδ^(18)O record correlates well with the Northern Hemispheric temperature,Dunde ice core record,and with temperature record in eastern China.The warming trend detected inδ^(18)O record from the last century is similar to that during the Medieval warm period.There is a dramatic increasing in methane concentration in the Dasuopu ice core,which reached 1031 nmol?mol-1 in 1997.Moreover,methane concentration in the Dasuopu ice core is about 15%-20%higher than that in Antarctica and Greenland.There is a positive correlation between methane concentration andδ^(18)O in Dasuopu ice core.

Recent area and ice volume change of Kangwure Glacier in the middle of Himalayas

This paper calculated and evaluated the area and ice volume changes of Kangwure Glacier in Mt.Xixiabangma,middle of Himalayas in the past 3 decades,based on the field survey of glacier boundary position by differential GPS and glacier depth by Ground Penetrating Radar(GPR),together with the topographic map and remote sense data.The studied data showed that the Kangwure Glacier has experienced significant mass deficit since the 1970s,with 34.2%of area loss,48.2%ofice volume loss and 7.5 m of average thickness decrease.This result revealed that the ice volume loss of Himalayan glaciers was more serious than expected.Analysis of meteorological data from two weather stations in the region of Mt.Xixiabangma,shows that the air temperature of this region has risen from the middle of the 20th century to the beginning of the 21st century.Significant retreat of Himalayas glacier driven by climatic warming will have a remarkable impact on hydrology and ecosystem.

Water isotope variations in the snow pack and summer precipitation at July 1 Glacier, Qilian Mountains in northwest China

This paper presents the stable isotope data of the snow pack and summer precipitation collected at the July 1 Glacier, Qilian Mountains in northwest China and analyses their relationships with meteorologi- cal factors. On an event scale, there is no temperature effect on the δ 18O values in the summer pre- cipitation, whereas the amount effect is shown to be clear. By tracing the moisture transport history and comparing the precipitation with its isotopic composition, it is shown that this amount effect not only reflects the change in moisture trajectory, which is related to the monsoon activities, but is also associated with the cooling degree of vapor in the cloud, the evaporation of falling raindrops and the isotopic exchange between the falling drops and the atmospheric vapor. As very little precipitation occurs in winter, the snow pack profile mainly represents the precipitation in the other three seasons. There are low precipitation δ 18O ratios in summer and high ratios in spring and autumn. The Meteoric Water Line (MLW) for the summer precipitation is δ D = 7.6 δ 18O + 13.3, which is similar to that at Delingha, located in the south rim of the Qilian Mountains. The MWL for the snow pack is δ D = 10.4 δ 18O + 41.4, showing a large slope and intercept. The deuterium excess (d) of the snow pack is positively correlated with δ 18O, indicating that both d and δ 18O decrease from spring to summer and increase from early autumn to early spring. This then results in the high slope and intercept of the MWL. Sea- sonal fluctuations of d in the snow pack indicate the change of moisture source and trajectory. During spring and autumn, the moisture originates from continental recycling or rapid evaporation over rela- tively warm water bodies like Black, Caspian and Aral Seas when the dry westerly air masses pass over them, hence very high d values in precipitation are formed. During summer, the monsoon is responsi- ble for the low d values. This indicates that the monsoon can reach the western part of the Qilian Mountains.

Response of monsoon vari-ability in Himalayas to global warming

Reconstructed annual net accumulation from the Dasuopu ice core recovered in Himalayas, with a good correlation to Indian monsoon, reflects a major precipitation trend in central Himalayas. The Dasuopu accumulation (DSP An) also shows a strong correlation to the Northern Hemispheric temperature. Generally, as the Northern Hemispheric temperature increases by 0.1 K, the accumulation decreases by about 90 mm and vise versa. Under the condition of global warming, especially since 1920, the Northern Hemispheric mean temperature has increased by about 0.5 K, whereas accumulation in Dasuopu ice core has decreased by about 450 mm. According to the relationship between accumulation and temperature, a scenario prediction of monsoon rainfall in central Himalayas is made.

Compositional characteristics of n-alkanes of the glaciers over the Tibetan Plateau and their environmental and climatic significances

We report on the concentration and compositional features of n-alkanes of natural and anthropogenic origins in the snow samples collected from the Qiyi glacier in the Qilian Mountains, the Yuzhufeng glacier in eastern Kunlun Mountains, the Xiaodongkemadi glacier in the Tanggula Mountains, and the Gurenhekou glacier in the Nyainqêntanglha Range. The results indicate a decrease in the total n-alkane concentration (T-HCs) from the northeast to the south over the Tibetan Plateau. The T-HCs in these studied areas were close to those in the Belukha and Sofiyskiy glacier, Russian Alati Mountains and the Dasuopu glacier in the Himalaya but were much higher than those in the Greenland ice sheet, suggesting that the mountain glaciers in the Asian continent may receive a higher loading of n-alkanes than the Greenland ice core. Moreover, the compositional characteristics of n-alkanes indicated that the n-alkanes in the studied areas were probably originated from the plant waxes as well as the fossil-fuel combustion exhaust, whereas the contribution from the lower organisms was small. In addition, the plant wax (Cn(wax)) and anthropogenic (non-Cn(wax)) contributions revealed that fast industrialization may have significant effects on the organic pollutant composition in glacier over the Tibetan Plateau and its circumference environment. Particularly, except for the Yuzhufeng glacier, the ΣnC21-/ΣnC22+ and (nC15+nC17+nC19)/(nC27+nC29+nC31) ratio decreased from the Qiyi glacier to the Gurenhekou glacier over the Tibetan Plateau, while the carbon preference index (CPI) values increased. These results indicate a decrease in terrigenous input while an increase in marine input from the northeast to the south over the Tibetan Plateau. These two ratios can be used as the climatic and environmental change indicators.

Sources and distribution of polycyclic aromatic hydrocarbons of different glaciers over the Tibetan Plateau

Twenty snow samples were collected from the Qiyi glacier in Qilian Mountains,the Yuzhufeng glacier in eastern Kunlun Mountains,the Xiaodongkemadi glacier in Tanggula Mountains,and the Gurenhekou glacier in Nyainqêntanglha Range over the Tibetan Plateau.The concentration and distribution features of sixteen priority Polycyclic Aromatic Hydrocarbons (PAHs) were determined by gas chromatography equipped with a mass spectrometry detector (GC-MS).The sources of these PAHs were explored as well.Our results indicated that the average concentrations of PAHs in snow were in the range of 20.45 60.57 ng/L.Maximum PAHs levels were found in the YZF glacier andminimum in the XDKMD glacier.However,no apparent regional distribution pattern of PAHs was found in the glaciers over the Tibetan Plateau.Moreover,the 2 4 ring low molecular weight PAHs predominated in snow samples and the concentrations of phenanthrene was the highest.Integrated factor analysis and isomer pair ratios suggested that PAHs of glaciers over the Tibetan Plateau were derived from low temperature combustion of coal and biomass,and partially from the exhaust gas of locomotives.Air mass back trajectory indicated that organic compounds detected in snowpit of these four glaciers,in the period of time they represented,mainly came from Central Asia and the arid area of Northwest China by westerly wind circulation.

Long-term glacier variations and the response to climate fluctuation in Qilian Mountains,China

Glaciers are considered to be‘climate-sensitive indicators'and‘solid reservoirs',and their changes significantly impact regional water security.The mass balance(MB)from 2011 to 2020 of the Qiyi Glacier in the northeast Tibetan Plateau is presented based on field observations.The glacier showed a persistent negative balance over 9 years of in-situ observations,with a mean MB of-0.51 m w.e.yr^(-1).The distributed energy-mass balance model was used for glacier MB reconstruction from 1980 to 2020.The daily meteorological data used in the model were from HAR v2 reanalysis data,with automatic weather stations located in the middle and upper parts of the glacier used for deviation correction.The average MB over the past 40 years of the Qiyi Glacier was -0.36 m w.e.yr^(-1)with the mass losses since the beginning of the 21st century,being greater than those in the past.The glacier runoff shows a significant increasing trend,contributing~81% of the downstream river runoff.The albedo disparity indicates that the net shortwave radiation is much higher in the ablation zone than in the accumulation zone,accelerating ablation-area expansion and glacier mass depletion.The MB of the Qiyi Glacier is more sensitive to temperature and incoming shortwave radiation variation than precipitation.The MB presented a non-linear reaction to the temperature and incoming shortwave radiation.Under future climate warming,the Qiyi Glacier will be increasingly likely to deviate from the equilibrium state,thereby exacerbating regional water balance risks.It is found that the mass losses of eastern glaciers are higher than those of western glaciers,indicating significant spatial heterogeneity that may be attributable to the lower altitude and smaller area distribution of the eastern glaciers.