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Glaciers reflect integrated climate signals from inter-annual to centennial timescales. In using glacier extent as a climate-change detector, the challenge is to distinguish the roles of the inter-annual climate variability and long-term climatic change on the glacier change. Using cosmogenic nuclide 10Be dating method and glacier dynamical models, this study numerically reconstructed glacier extents at ~ 1850s AD (latest Little Ice Age period) in the Keqiong Qu I, Keqiong Qu II, Taqiong Qu I, and Taqiong Qu II valleys around the Kuoqionggangri peak, southern Tibetan Plateau, and quantified the effects of inter-annual summer temperature variability and long-term summer temperature change on the glacier retreats since then. Without change in mean annual precipitation, the summer temperature decrease of 0.40–0.53 °C from present was required to sustain the glacier lengths at their respective ~ 1850s AD moraines in the four valleys. The climate inferences from the glacier-climate modeling were similar to reconstructions at other glaciers on the Tibetan Plateau and the changes in long term climate reanalysis (HadCRUT5, BEST and NOAA 20CR v3). Forced by the inter-annual variabilities in summer temperature and annual precipitation, the glaciers had excursions of 150–200 m (5–8% of their lengths) from the ~ 1850s AD moraines. We therefore argued that the climate change was largely responsible for the glacier retreats from the ~ 1850s AD moraine positions in the region. [ABSTRACT FROM AUTHOR]

Inter-annual climate variability has the potential to induce hundred-to-thousand meters of glacier length change, comparable to the glacier retreats from their Little Ice Age (LIA) positions (Roe and O'Neal, 2009). Distinguishing the roles of inter-annual climate variability and climate change in glacier changes can help us read the true climate signal from the history of glacial activity and provide a basis for detailed attribution of currently observed glacier retreats. Here, we used ArcGIS tools to reconstruct the LIA glacier in the Hailuogou catchment on the southeastern Tibetan Plateau (TP) and calculated the corresponding glacier equilibrium-line altitude (ELA). Based on the LIA ELA, we inferred the climate change supporting the LIA glaciers in the region. Further, we quantified the impact of inter-annual climate variability on the Hailuogou Glacier change using a three-stage linear model. During the LIA, the area of the Hailuogou Glacier was 42.64 km2 and its volume was 3.73 × 109 m3. The LIA ELA was 5068 m above sea level (a.s.l.), lowering by 213 m relatively to the present. The LIA summer temperature was estimated to be ∼1.31–2.21 °C colder than the present with the LIA precipitation constraint being 90–100% of the modern precipitation. Forced by the inter-annual variabilities in summer temperature and annual precipitation, the Hailuogou Glacier has a possible maximum negative excursion of 459 m, which can only explain 19.3% of the actual retreat since the LIA. According to the probability density function (PDF) of the modeled length anomalies, the likelihood is <1% for the actual glacier retreat completely due to the inter-annual climate variability. We therefore argued that the inter-annual climate variability alone cannot explain the glacier retreat since the LIA in the Hailuogou catchment. Further, glacier geometry and topography might be the main factors determining the strength of the response of the Hailuogou Glacier to inter-annual climate variability. • The LIA summer temperature was estimated to be ∼1.31–2.21 °C colder than the present. • The LIA Hailuogou Glacier had an area of 42.64 km2 and a volume of 3.73 × 109 m3. • The LIA ELA was 5068 m above sea level (a.s.l.), lowering by 213 m relatively to the present. • The inter-annual climate variability alone cannot explain the retreat of Hailuogou Glacier since the Little Ice Age (LIA). [ABSTRACT FROM AUTHOR]

Mountain glaciers are one of the most sensitive indicators of climate change. Reconstructing past glacier extents provides valuable insights into the climate change for specific regions where instrumental records are not enough and even absent. In the paper we mapped the outlines for 691 Little Ice Age (LIA) glaciers in terms of prominent moraines beyond contemporary glaciers in the Tanggula Mountains, central Tibetan Plateau (TP). Based on these glacier outlines, we reconstructed the ice thicknesses and surfaces for the LIA glaciers in the region. Accordingly, we calculated the equilibrium-line altitudes (ELAs) for contemporary and LIA glaciers. By comparing the ELAs between the contemporary and LIA glaciers, we estimated the LIA summer temperature decreases in different subregions of the Tanggula Mountains. Since the LIA, the ELA have risen by 35.6 ± 18.8 m, 26.1 ± 17.6 m, and 63.1 ± 38.6 m in the respective western, central, and eastern subregions of the Tanggula Mountains. Assuming no change in precipitation, the LIA summer temperature would decrease by 0.22 ± 0.12 °C, 0.14 ± 0.09 °C, and 0.34 ± 0.21 °C in the three subregions, respectively. Moreover, glaciers in the western, central, and eastern subregions have lost 13.3%, 23.9%, and 42.8% of their area, 15.4%, 25.3%, and 39.6% of their length, and 20.8%, 39.0%, and 61.0% of their volume, respectively. By compiling the LIA ELA data from previous studies, we also estimated the LIA summer temperature changes for other regions of the TP. The LIA ELA and summer temperature changes relative to the present showed a decreasing trend from the edges towards the interior on the TP. • LIA glaciers and summer climate were reconstructed at the Tanggula Mountains. • LIA summers were 0.22 ± 0.12 °C, 0.14 ± 0.09 °C, and 0.34 ± 0.21 °C cooler than present in three subregions. • Summer temperature change had a decreasing trend from the edges towards the interior on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Glacial chronology is critical to the reconstruction of former glaciers. The West Kunlun Mountains represent one of the most important areas for understanding the response of glacier to climate change in regions dominated by the Westerlies. However, accurate chronologies for Quaternary glaciations in this area are still lack. In this work, we identified two sets of moraines at the eastern side of the Guliya ice cap in the West Kunlun Mountains and constrained their emplacement times using the cosmogenic 10Be exposure dating method. The outer moraine set, within ~6 km in front of the modern glaciers, was dated to 231.8 ± 14.7 ka ago, and the inner moraine set, within ~3.5 km downstream of the modern glaciers, was dated to 113.7 ± 7.0 ka ago. This suggested that two glacier advances could have occurred during the marine isotope stages (MIS) 8–7 and MIS 6–5, respectively, and the glaciers became progressively less extensive between these two glacial periods at the eastern side of the Guliya ice cap. Comparing our dating results with previous studies in the Gurla Mandhata, the Tashkurgan Valley, the Muztag Ata and Kongur Shan, we concluded that regional aridification was the most likely explanation for the progressively less extent of the two glacier advances in the western Tibetan Plateau regions. [ABSTRACT FROM AUTHOR]

During the last glacial termination, a warming trend was generally interrupted by rapid millennium-scale cold reversals, such as the Greenland (Isotope) Stadial 1 (GS-1) and GS-2a events. To understand how glaciers on the Tibetan Plateau (TP) responded to these rapid climate events, this study constrained the timing and extent of three glacial events during the late-glacial period. Specifically, using a cosmogenic 10Be exposure dating method, we dated three prominent glacial moraines (PM1, PM2, PM3) back to 15,850 ± 980, 14,140 ± 880, and 12,430 ± 790 yr in the Pagele valley, southern TP, corresponding to GS-2a, Greenland Interstadial 1 (GI-1), and GS-1, respectively. By simulating glacial extents forced by different climate scenarios, the study constrained the temperature decreases relative to present to be 2.6°C–2.9°C, ~1.6°C, and 1.4°C–1.5°C during the GS-2a, GI-1, and GS-1 periods in the region, with precipitation values of 60%–80%, ~100%, and 80%–90% of present value, respectively. Considering information from oceanic and atmospheric circulation, the study suggested that on the TP, the glacial events during the last glacial termination were well connected with the millennium-scale climate events in the North Atlantic region through the westerlies, while the Indian summer monsoon played a positive role in sustaining the glaciers under the warming climate trend. [ABSTRACT FROM AUTHOR]

A well‐preserved Last Glacial Maximum (LGM) moraine set in the Quemuqu Valley on the eastern slope of the Qiongmu Gangri Peak offers great potential for reconstructing LGM glacier extent and examining LGM climate in the region. This study employed a coupled and physics‐based mass balance and ice‐flow model to investigate glacier sensitivities to climate in the valley. Based on the sensitivity tests and the well‐preserved LGM moraines, the study also reconstructed the LGM glacier extent in the valley and assessed the magnitude of cooling for the LGM period. Model results suggest that the Quemuqu Valley sustained an ice volume of 6.80±0.16 km3 in the LGM period. Temperature depression of 3.1–4.3 °C, combined with 30–70% modern precipitation, is likely to have supported the LGM glacier extent in the valley. The temperature inference for the LGM period is comparable with other independent palaeoclimate evidence in the region. However, there is a large difference in the reconstructed glacier volume (ice thickness) between previous research and the current study. The glacier model used here directly calculates the ice thickness and needs relatively less field evidence to constrain the model simulations. It is therefore advocated to use such a model to reconstruct past glaciers and their corresponding climates for other valleys of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The timing and extent of late Quaternary glaciation in the Hailuogou valley of eastern Tibetan Plateau have been extensively studied over past decades. Debate however exists in the timing of the Gongga II moraine that represents the maximum glaciation in the Hailuogou valley. Furthermore, the Gongga II glaciation is not quantitatively reconstructed; and what climate conditions could support this maximum glaciation is unknown. This study used a glacier-climate model driven by data from local weather stations to simulate the Gongga II glacier extent by fitting modeled glaciers to field geological evidence. Running multiple simulations with different temperature-precipitation combinations, we inferred the climate scenarios sufficient to generate the Gongga II glacier extent. The modeled Gongga II glaciers have an area of ∼119 km 2 and an average volume of 1.35 × 10 10 m 3 , with an average equilibrium-line altitude of 4050 m asl. Combined with other independent climate reconstructions, the glacier-climate model simulations suggested that the Gongga II glacial stage most likely occurred in the LGM. [ABSTRACT FROM AUTHOR]

Improvements in understanding glacial extents and chronologies for the southeastern slope of the western Nyaiqentanglha Shan on the Tibetan Plateau are required to understand regional climate changes during the Last Glacial cycle. A two-dimensional numerical model of mass balance, based on snow–ice melting factors, and of ice flow for mountain glaciers is used to assess the glacier sensitivity to climatic change in a catchment of the region. The model can reproduce valley glaciers, wide-tongued glaciers and a coalescing glacier within step temperature lowering and precipitation increasing experiments. The model sensitivity experiments also indicate that the dependence of glacier growth on temperature and/or precipitation is nonlinear. The model results suggest that the valley glaciers respond more sensitively to an imposed climate change than wide-tongued and coalescing glaciers. Guided by field geological evidence of former glacier extent and other independent paleoclimate reconstructions, the model is also used to constrain the most realistic multi-year mean temperatures to be 2.9–4.6°C and 1.8–2.5°C lower than present in the glacial stages of the Last Glacial Maximum and middle marine oxygen isotope stage 3, respectively. [ABSTRACT FROM AUTHOR]

Well-preserved Late Glacial moraines in the Barenduo and Yuqiongqu valleys on the eastern slope of the Samdainkangsang Peak present an opportunity to reconstruct glacier extents and examine the character of the climate during the Late Glacial stage in the Nyaiqentanggulha Mountains. This study employs a coupled mass-balance and ice-flow model to reconstruct the glacier extents in the two valleys and assess the magnitudes of temperature and precipitation change during the Late Glacial period. Model results indicate that during the Late Glacial, the Barenduo valley contained an ice volume of 1.67×108 m3, with the equilibrium-line altitude (ELA) being ~5500 m asl; and the Yuqiongqu valley had an ice volume of 5.56×108 m3, with the ELA being ~5470 m asl. A climate scenario, temperature depression of 2.6-2.8°C and 60-70%, percent of modern (1981-2010) precipitation, can sustain both of the Late Glacial glacier extents in the two valleys. A 50% increase or decrease from modern precipitation would have been coupled with the respective Late Glacial temperature depressions of 1.6 and 3.0°C in the Barenduo valley, and 2.1 and 2.8°C in the Yuqiongqu valley. [ABSTRACT FROM AUTHOR]

We present simulations for the late-Holocene glacier advances in the Hailuogou catchment, Gongga Shan, in attempts to test the glacier sensitivity to climate changes and constrain the climate conditions that support these glacier advances. We use a coupled mass-balance and ice-flow model parameterized using empirical glaciological and climatological data to simulate the glacier extents by fitting modeled glaciers to corresponding glacial landforms. The glacier sensitivity test showed that in the Hailuogou catchment, glacier area expands increasingly quickly until 4°C cooling, beyond which decreased expansion occurs up to at least 5°C cooling, but the modeled glacier volume increases steadily up to 5°C with an approximate linear rate being 1.1 × 109 m3/0.5°C. The temperatures were estimated to be 1.9–3.1°C, 1.5–2.6°C, and 1.0–2.2°C cooler than present for the respective Guanjingtai, Hailuogou, and ‘Little Ice Age’ (‘LIA’) Maximum glacial stages, considering a realistic precipitation field being 80–120% of present value. Model results also suggested that the Hailuogou catchment was covered by glaciers of 64.1, 59.3, and 53.8 km2 and ice volumes of 8.79 × 109, 7.99 × 109, and 6.92 × 109 m3 in the Guanjingtai, Hailuogou, and ‘LIA’ Maximum glacial stages, respectively. These findings help to understand the relationships between glacier dynamic and climate change and the hydrological evolution in the Hailuogou catchment. We therefore encourage using the model as a powerful tool to retrieve past ice extents and evaluate their related climate conditions on the vast Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Glaciers respond sensitively to climate change and paleoclimate conditions can be inferred from the geomorphic evidence by reconstructing equilibrium line altitude ( ELA ) and by modeling glacier mass balance and ice flow. However, such work has not been extensively carried out on the vast Tibetan Plateau, and thus the knowledge of glacier sensitivity to paleoclimate change and paleoglacier volume is still lacking on the plateau. Recent improvements in understanding glacial extent and chronology in the Payuwang Valley, southern Tibetan Plateau, present an opportunity to estimate the paleoclimate conditions during the Last Glacial cycle. Using a coupled mass-balance and ice-flow model, this study tests the glacier sensitivity to ELA change in the Payuwang Valley. By fitting modeled glaciers to the corresponding moraine positions, we reconstruct glacier extents probably occurred at oxygen isotope stage 3 (MIS 3) and Last Glacial Maximum (LGM) in the valley and infer the related climate conditions that could have supported these glacier advances. The glacier sensitivity tests indicate that in the Payuwang Valley, the glaciers responded to centennial-scale shifts in climate. With ELAs below 5600 m asl, the tributary glaciers coalesce into the main valley and expand rapidly there. The model results also show that the Payuwang Valley contained ice volumes of ~ 1.58 × 10 9 m 3 and ~ 1.23 × 10 9 m 3 with ELA lowering values of 370 m and 340 m in the MIS 3 and LGM glacial advances, respectively. By examining other independent paleoclimatic reconstructions, we conclude that during the MIS 3 glacier advance, the temperature was only 1.5 °C lower or even 0.2 °C higher than the period of 2005–2008 with precipitation 40–100% higher than the 2005–2008 amount; and during the LGM glacier advance, the temperature was 3.3–4.4 °C lower than the period of 2005–2008 with the precipitation 30–70% lower than the 2005–2008 amount. These estimates add to the knowledge of better understanding the relationship between glacier dynamic and climatic change on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The Last Glacial Maximum (LGM) featured a major cooling of Earth's climate, after which the climate evolved in the largest reconfiguration of the past 100 ka. Despite its significance, full understanding of the climate history during and since the LGM is still lacking on the eastern Tibetan Plateau. Recent improvements in understanding glacial extents and chronologies in the Yingpu Valley, eastern Tibetan Plateau present an opportunity to estimate the glacial climatic conditions during and since the LGM. Using a relatively new glacier-climate model, this study reconstructs glacier advances in the Yingpu Valley and quantifies the related climate conditions during the LGM, Lateglacial, and Late Holocene glacial stages. The model results show that the Yingpu Valley contained ice volumes of ∼1.65 km 3 , 1.03 km 3 , and 0.29 km 3 with equilibrium line altitude (ELA) lowering values of ∼500 m, ∼410 m, and ∼150 m in the three successive glacial stages, respectively. By examining other independent paleoclimatic reconstructions, it is concluded that the temperature decreased by 4.0–5.9 °C, 3.4–3.7 °C, 0.3–0.6 °C with the precipitation amounts being 40–80%, 80–100%, and 100–110% of modern values during the LGM, Lateglacial, and Late Holocene glacial stages, respectively. The climate estimates for the three glacial stages are generally in agreement with other climatic proxy records on the Tibetan Plateau and atmospheric circulation modeling results. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of the Little Ice Age (LIA) on the Tibetan Plateau (TP) is of critical importance for understanding the climate changes over the past millennium. However, the data associated with the extents and chronologies of TP LIA moraines are highly dispersed in literature. Lack of systematic integration of these data hampers us to further understand the nature of the LIA, especially from a perspective of whole TP. The paper reviews multiple types of dating on LIA moraines to examine the timing and nature of the LIA on the TP. These include ages of radiocarbon 14C, lichenometry, and cosmogenic radionuclide (CRN), by which we can cross-date the same or morphostratigraphically similar landforms. LIA moraines on the TP are usually present a few hundred to thousand meters beyond the contemporary glaciers. The morphological and stratigraphic evidence indicates multiple periods of glacier advance during the last millennium (LIA). At present, available chronology evidence allows to fully compare the timing of the LIA maximum extents. The glaciers reached and retreated from their LIA maximum extents by an asynchronous pattern between different parts of the TP. The majority of glaciers advanced to their LIA maximum extents at late-14th and early-14th century on the southern and northwestern TP, respectively. The glaciers retreated from their LIA maximum extents during 16th to early-18th, late-14th to early-15th and early-16th century on the southern, northwestern, and northeastern TP, respectively. In addition, the glacier advance period of late-18th to early-19th centuries and retreat period of late-19th century are common on the whole TP. Comparison with ice core records suggests that on the TP, the glacier fluctuations responded more strongly to temperature than to precipitation. By comparison of the LIA chronologies from a global perspective, this paper also concludes that the LIA maximum extents occurred commonly earlier on the TP than in North Atlantic and Southern Hemisphere regions, despite of the variability in the timing of LIA maximum extents on the TP and in the North Atlantic regions. Further, more chronology programs, especially in the central TP, are necessarily needed to improve our understanding of the LIA glacier fluctuations. [Copyright &y& Elsevier]

Abstract: Fully understanding the timing and climate of Last Glacial Maximum (LGM) is still lack in the head of the Tashkurgan Valley, northwest Tibetan Plateau (TP). The recent improvements in cosmogenic 10Be exposure dating and glacier modeling present an opportunity to estimate the LGM climatic conditions. In the paper, we investigated the moraines and used the 10Be exposure dating on the moraine boulders to constrain the timing of the LGM, the Kuzigun glacial stage in the head of the Tashkurgan Valley. Then, we used a coupled mass-balance and ice-flow model to quantify the paleoclimate from past glacier extents constrained by mapped and dated Kuzigun glacial moraines in the area. We showed that the glaciers terminated at an elevation of 4100–4200 m asl during the Kuzigun glacial stage and the glacial stage occurred during or slightly before 15–23 ka, corresponding to the timing of the global LGM. The modeled mass balances indicated that present-day equilibrium line altitude (ELA) ranges from 5150 to 5250 m asl, and LGM ELA is between 4550 and 4600 m asl in the area, suggesting an ELA lowering of ∼600 m during the LGM. Model results suggested that the temperature during the LGM in the head of the Tashkurgan Valley is 5–8 °C colder than today, considering a 30–70% reduction in precipitation compared to today. The paleoclimate estimates are generally consistence with previous studies that showed the LGM climate was colder and drier than today on the TP. [Copyright &y& Elsevier]

Abstract: Clear understanding of how alpine glaciers respond to climate change is critical to accurately evaluate water resources and to retrieve climate information from the alpine glaciers. However, different glaciers may have different responses to climate change. This study focuses on two branches of Glacier No. 1 at the head of Urumqi River, Tianshan, China. These two branches, West Branch (WB) and East Branch (EB), have experienced the same pattern of climate warming since their separation in 1993. However, these glaciers have responded differently as observed by fieldwork and analysis of their annual mass balances, lengths, areas, equilibrium line altitudes (ELAs). To illustrate the different responses of climate change (increase in both temperature and precipitation), the glacier length response time (T rl) and climate sensitivity (C) are calculated for the two branches. The length response time and climate sensitivity are 1.89y and 8.81 for the EB, and 1.63y and 5.92 for WB. The different responses are interpreted to be controlled by glacial/topographical features with larger slopes and smaller areas, making the WB more sensitive to the recent climate warming. [Copyright &y& Elsevier]

Abstract: The relationship between climate and glacial equilibrium-line altitude (ELA) during the Last Glacial Maximum (LGM) has recently received considerable interest. However, in the headwaters of Urumqi River in northwest China, a systematic reconstruction for the paleo-ELAs had not been completed to permit regional and large-scale paleoclimate inferences. Recent improvements in dating and understanding of glacial extents provide the possibility to use glacial reconstruction to infer the paleoclimate. To improve the ability to obtain paleoclimate information, the ELAs during the local LGM (MIS2–3) and modern time (1998–2004) were constructed by using an integrated method. The regional tectonic uplift is considered when calculating the LGM ELAs in order to improve their precision and thus obtain a better estimate of the paleoclimate. The estimated ELA values were input into a robust equation to derive the forcing paleoclimatic conditions. During the local LGM in the study area, the ELA was between 3420 and 3560 m a.s.l., 493–633 m lower than modern ELA. Considering energy and mass balance in the equation to account for the ELA decrease, during the LGM, the temperature decreased by 5.42–6.30 °C and the precipitation was ∼30% compared to the present. [Copyright &y& Elsevier]

Abstract: The Kanas River originates on the southern slope of Youyi Peak, the largest center of modern glaciers in Altai Mountains, China. Three sets of moraines and associated glacial sediments are well preserved near the Kanas Lake outlet, recording a complex history and landscape evolution during the Last Glacial. Dating the moraines allows the temporal and spatial glacier shift and climate during the Last Glacial to be determined, and then constrains when and how the Kanas Lake basin was formed. Dating of the glacial tills was undertaken by utilizing the optically stimulated luminescence (OSL) method. Results date four samples from the three sets of moraines to 28.0, 34.4, 38.1, and 49.9ka and one sample from outwash sediment to 6.8ka. The Kanas Lake basin is a downfaulted basin and was eroded by glacier before 28.0ka, and the glacial moraines blocked the glacier-melt water after the glacier retreat, which made the present-day Kanas Lake eventually form at least before 6.8ka BP. In Altai Mountains, the glacier advance was more extensive in Marine Isotope Stage (MIS) 3 than MIS 2, probably because the mid-latitude westerlies shifted northward and/or intensified during the MIS 3, resulting in a more positive glacier mass balance. Nevertheless, the Siberian High dominated the Altai Mountains in MIS 2, resulting in a relative decrease in precipitation. [Copyright &y& Elsevier]

The use of quartz is critical to the electron spin resonance (ESR) dating of sediments and fault gouges. The germanium center (Ge center) in quartz is a commonly used color center employed in ESR signal measurement. Although Ge center signals in quartz can be detected using an ESR spectrometer, they are weak and sometimes undetectable. Impurities in quartz grains can further aggravate these deficiencies and may even invalidate any attempt to repeat ESR ages due to the deficiencies evident in the processes used in sample preparation. Using sieving, carbonate-organic matter removal, water flotation, magnetic separation, heavy liquid separation, and HF solution etching, we separated quartz, feldspar (plagioclase), mica, and the heavy minerals and measured the ESR signal in each of them to examine the impact of impurities within mineral grains on the ESR signals. From the ESR spectra, we observed intense ESR signals in feldspar and the heavy minerals and weak signals in mica at the same positions as the Ge center in the quartz. The ESR signals in the feldspar proved to be the most intense and overrode the peaks exhibited by the Ge center in the quartz. Feldspar is commonly associated with quartz in sediments, but it is difficult to separate it from quartz as their colors, specific gravities, and magnetic properties are similar. Any ESR signal in quartz containing foreign minerals would therefore be likely to be heavily disturbed by the signals from these foreign minerals, particularly from the feldspar and heavy minerals. ESR signals in the feldspar decreased similarly to those in the quartz when exposed to sunlight, declining by 70%–80% after being exposed for 50 h. Such declination was more obvious in high-altitude areas than in low-altitude areas. Our results indicate that highly pure quartz is required when dating; we would therefore strongly suggest that the procedures for the purification of quartz grains should include floating, heavy liquid separation, and HF solution etching to remove the feldspar, heavy minerals, and any remnant magnetite. Such a procedure would guarantee that the signal that is measured comes from the quartz alone, allowing repeatable measurements using the same spectrometer as well as valid comparisons between the spectrometries derived from different spectrometers. [ABSTRACT FROM AUTHOR]

The Chinese Altai is located on the northern edge of Central Asia. Rich geological records of Quaternary glaciations are preserved in this area. However, the glacial history in the Chinese Altai has hardly been investigated. This study aims to rebuild the regional glacial history in the Kanas Valley of the Chinese Altai. We present 14 electron spin resonance (ESR) ages and 3 optically stimulated luminescence (OSL) ages from glacial landforms. By integrating with ages from previous studies, five major glacial advances are identified during Marine Oxygen Isotope Stages (MIS) 6, 5, 4, 3 and 2, with ages of 167.0 ± 16.0–123.0 ± 18.0 ka, 97.0 ± 19.0–78.0 ± 7.0 ka, 76.0 ± 16.0–73.1 ± 6.6 ka, 52.1 ± 7.8–34.4 ± 4.2 ka, and 28.0 ± 3.3–16.1 ± 1.5 ka respectively. The glacial advance during MIS 5 is the local Last Glacial Maximum, and glaciers became successively more restricted from MIS 5 to MIS 2. In addition, the extensive MIS 3 glacial advance in the Chinese Altai contrasts with the absence of MIS 3 glacial advance in the Mongolia Altai. These glacial patterns reflect that precipitation brought by the westerlies might play a primary role on driving glacial advances during the Last Glacial in the Chinese Altai. This glacial chronology is in reasonable agreement with existing glacial chronologies from other parts of the Altai, Tian Shan and Pamir, indicating similar climate controls on the patterns of Quaternary glaciation across Central Asia Highlands. [ABSTRACT FROM AUTHOR]

Glacier changes in the Karakoram have shown a complex pattern since the recent decades with the coexistence of advancing, retreating, and stable glaciers, but the mechanisms driving these changes remain, for the most part, unclear. We examined the changes in glacier length, area, and elevation in the Hunza Basin of the upper Indus River region, western Karakoram, using CORONA remote sensing data, Landsat MSS/TM/OLI imagery, SRTM digital elevation model (DEM), and GLAS/ICESat altimeter data. We delineated 108 glaciers within the study area. The total area of these glaciers decreased 28.86 km 2 , or 1.36%, from 2115.48 km 2 in 1973–2086.62 km 2 in 2014. The most significant reduction in ice coverage occurred between 1992 and 1998, when glaciers retreated on average at a rate of −2.97 km 2 /yr (0.85% of the total coverage measured in the 1970s). In contrast, many glaciers advanced from 2008 to 2014 and glacial coverage increased by 0.19 ± 0.00 km 2 . In comparison to fast retreating glaciers in the Hindukush and the Trans-Himalayan regions, the glaciers in the Hunza Basin are relatively stable. The topographical characteristics and the size of the glaciers have direct impacts on glacial changes in the Hunza Basin. Specifically, significant changes occurred mainly below 5500 m above sea level, glaciers retreated more extensively on steep slopes than on gentle slopes, and small glaciers retreated relatively faster than large glaciers. The overall pattern of glacial retreat is related to the warming trend in summer temperature, whereas the relative stability of glaciers in the Hunza Basin, as well as their recent advance (2008–2014), is likely driven by increasing autumn and winter precipitation. [ABSTRACT FROM AUTHOR]

Only a few studies of Quaternary glaciation have been conducted in the central Kunlun Mountains, hindering a full understanding of Late Pleistocene and Holocene climatic changes on the Tibetan Plateau. This study presents 30 new 10Be surface exposure ages from five moraine crests, two moraine platforms and two glaciofluvial terraces on the northwestern slopes of the Ulugh Muztagh in the central Kunlun Mountains. The moraine ages indicate that an old glacial advance occurred no later than ∼87.10 ka, an extensive glacial advance at ∼35.61 ka and Holocene advances at ∼7.61 ka, ∼1.65 ka, ∼0.69 ka, and ∼ 0.36 ka. Two glaciofluvial terraces were tentatively determined to have been deposited at ∼24.87 ka and ∼ 17.35 ka, possibly implying the occurrence of limited global Last Glacial Maximum (LGM) and Heinrich Stadial 1 glacial advances. After combining these findings with geomorphic evidence, it was inferred that glacial coverage was more extensive during MIS 3 than the global LGM, indicating that the timing of the LGM in the Ulugh Muztagh was asynchronous with that of the monsoon-dominated Tibetan Plateau. Reference to other palaeoclimatic archives suggested that glacial advances since MIS 3 were most likely driven by a combination of cool to cold temperatures and a relatively humid climate. The limited global LGM advance was attributed to increased aridity. • MIS 5 or older, MIS 3 and four Holocene glacial advances were determined. • LGM moraines were absent, a limited LGM glacial advance was geomorphically inferred. • Glacial advances since MIS 3 were driven by a cool to cold and humid climate. • The limited LGM advance could be attributed to increased aridity. [ABSTRACT FROM AUTHOR]

Climatically, the eastern Himalaya are mainly controlled by the Indian Summer Monsoon (ISM) and important region for understanding the relationship between ISM and glacial change. This region is therefore useful for studies of the relation between glacial changes and ISM. Using a geomorpho-stratigraphic method combined with GIS, we investigated and mapped the outmost lateral-frontal moraine of the most extensive glaciations that occurred in the Basongcuo (BSC) catchment, near the eastern Himalayan syntaxis. Using optically stimulated luminescence (OSL) and 10 Be surface exposure dating technique, we dated five boulders and 23 sediment samples. The resultant OSL and 10 Be ages show that the region's glaciers were at their most extensive positions between ∼16 and 31 ka. Glacial coverage was 507.5 km 2 , 9.9 times greater than it is today (51.5 km 2 ), with an equilibrium line altitude (ELA) depression of ∼690 m. The rapidity with which the Last Glacial Maximum (LGM) glacial advance and retreat occurred suggests that temperature was the dominant control on glacial change. [ABSTRACT FROM AUTHOR]

Abstract: The Diancang Massif is located in a region linking the Tibetan and Yungui Plateaus. Climatically, it is in a transition belt between the south and middle subtropical zones, controlled by Indian monsoon and westerlies. Thus, this study provides more evidences on the evolution of Indian monsoon since the Holocene. We reconstruct the history of climate on the Diancang Massif since 11.5 ka, using integrated correlation of glacial activities, early human settlement sites, and climate proxies abstracted from variations in grain size, magnetic susceptibility, geochemical composition, and pollen in lacustrine sediments. Six climatic stages have been identified. Stage I, from 11.5 ka to 9.0 ka, is a relatively wet period, corresponding to the onset of the Holocene; from 9.5 ka to 6.0 ka, the climate is arid; a cold period follows from 6.0 ka to 5.3 ka, and this is succeeded by a temperate stage from 5.3 ka to 4.0 ka; from 4.0 ka to 0.73 ka the climate is again arid. Compared with other regions dominated by the Indian monsoon, there is a delay in response of the climate on the Diancang Massif to the onset of the Holocene. [Copyright &y& Elsevier]

Quantifying the timing and extent of late Quaternary glaciations across the Tibetan Plateau (TP) is critical to understanding regional and global climate changes. Despite significant advancements in our knowledge of glacial histories of the TP over the past several decades, chronological constraints are still lacking for the high glaciated mountain ranges on the northern TP, including the Altyn Tagh Range. In this study, we provide thirty-two new 10Be exposure-ages to construct a late Quaternary glacial history of the Altyn Tagh Range at the Altyn "Pass" and Akato Tagh. The dating results from Altyn "Pass" indicate that glacier might have fully melted out of this area after Marine Isotope Stage 3 (MIS 3). The tentatively-defined minimum moraine ages north of Akato Tagh show that four glacial culminations possibly occurred during MIS 5, MIS 4, MIS 3 or 2, and the late Holocene. These dating results, together with the compiled exposure-ages from Sulamu Tagh, imply that the last glacial glacier fluctuations along the Altyn Tagh Range were likely driven by several factors: North Atlantic climate oscillations, northern hemispheric high-latitude summer solar insolation, atmospheric CO 2 concentrations, and geometry of glacier catchment. The progressive reduction in glacier extent during the last glacial is likely associated with available precipitation, controlled by the mid-latitude westerlies. • No glacial evidence post-dating MIS 3 has been found in the Altyn "Pass" area. • Glacial advance north of Akato Tagh progressively shrank since MIS 4. • The last glacial glacier advances mismatch with the NH ice sheets across the range. • Whether the LGM is synchronous or not across the Altyn Tagh Range remains equivocal. [ABSTRACT FROM AUTHOR]

Glaciers have remained relatively stable in the Karakoram over the past few decades, in contrast to rapid retreat in other regions of the Tibetan Plateau and its surrounding mountains. This study investigated glacial changes in the Karakoram since the Little Ice Age (LIA) to examine if this relatively stable scenario has occurred for a longer term. We mapped 432 contemporary glaciers and their corresponding 313 LIA glaciers in the Hunza Basin, western Karakoram, using Google Earth and Landsat images. We also derived geomorphometric parameters for each glacier using the Shuttle Radar Topographic Mission digital elevation model and reconstructed the equilibrium line altitudes (ELAs) for both contemporary and LIA glaciers based on the toe-to-ridge altitude method. Our results revealed 6.6% decrease in the total area, 14.5% shortening in the total length along the flowline of each LIA glacier, and approximately 98 m rising in the mean ELA since the LIA. The relative area reduction was strongly affected by geomorphometric factors and small glaciers tended to experience relatively large areal reductions. In contrast, the change in ELA was not strongly affected by glacial area but had some correlations with slope and mean elevation. Compared to other areas on the Tibetan Plateau and its surrounding mountains, glacial changes have been less extensive in the Hunza Basin since the LIA. These findings confirmed a relatively stable behavior of glaciers in this area since the LIA and a strong control of local geomorphometric characteristics on glacial change. • Glacial changes were investigated in the Hunza Basin since the Little Ice Age (LIA). • LIA glacial changes were less extensive in this basin than its nearby glaciated areas. • LIA glacial changes were strongly controlled by local geomorphometric factors. [ABSTRACT FROM AUTHOR]

Numerous studies of changes in the climate, vegetation and landscape responses of the Tibetan Plateau (TP) during the Holocene have been published in recent decades. However, several conflicting interpretations are evident within these studies and a comprehensive review of the topic is needed to reconcile them, and thus to provide an improved understanding of the history and forcing mechanisms of Holocene environmental changes within the region. Here we review the evidence for changes in climate (temperature, precipitation/moisture), vegetation and landscape attributes (glacier and eolian activity) on the TP during the Holocene. Our main conclusions are as follows. 1) The patterns of Holocene mean annual temperature change on the TP remain controversial; however, an early to middle Holocene summer temperature maximum is evident, which coincided with high summer insolation and a strengthening of the Indian summer monsoon (ISM). This suggests that the summer land-sea thermal gradient, impacted by the temperature of the TP, may be an important factor driving orbital-scale ISM changes. 2) Lake-level records indicate an optimum in moisture conditions on the southwestern (SW) TP in the early Holocene, while on the northeastern (NE) TP the optimum occurred in the middle to late Holocene. This out-of-phase or anti-phased relationship may be linked to the role of the ISM in dominating precipitation on the SW TP, while the westerlies and East Asian summer monsoon dominated the precipitation on the NE TP. 3) Most of the lake-sediment-based stable isotope records (δ18O and leaf wax δD) exhibit a pattern similar to that of stalagmite δ18O records from monsoonal Asia, reflecting the dominance of large-scale patterns of atmospheric circulation, rather than localized moisture changes reflected by lake level records. 4) A synthesis of pollen records reveals that the extent of forest was maximal in the mid-Holocene, while from the early Holocene onwards alpine steppe shrunk and alpine meadow and desert gradually expanded. 5) Evidence of glacier advance increased slightly during the early Holocene, decreased during the mid-Holocene, and then increased substantially after 3 ka BP. 6) The integrated ages of eolian sand and loess from the NE TP reveal that eolian activity intensified during the early and late Holocene. Site inter-comparisons reveal that regional climate change played a major role in modulating changes in vegetation and other landscape attributes. Overall, producing Holocene climate reconstructions for the entire TP remains a major challenge even though much progress has been made. Further improvements in terms of the spatial coverage of high-resolution paleoclimatic records with robust chronological control, and a deeper understanding of the specific climatic significance of several climatic proxies, will facilitate an improved understanding of how the monsoon and the westerlies interacted and their impacts on vegetation and landscape changes on the TP. • First comprehensive review of Holocene climatic and environmental changes for TP. • Early to middle Holocene summer temperature maximum on TP, driving a strong ISM. • Divergent patterns of changes in moisture conditions between the northern and southern TP. • Regional climate change modulating changes in vegetation and other landscape attributes. [ABSTRACT FROM AUTHOR]

Wildfire activity is an important part of natural ecosystems and is strongly influenced by climate and vegetation changes. Given this, the reconstruction of wildfire history is crucial to understanding the interrelationships between past climate change and fire dynamics, especially in terms of revealing past climate change characteristics during particularly important periods. In this study we employed a macro-charcoal sequence to reconstruct the wildfire history in the Yinchuan Basin (an arid and semi-arid region in China) during the past 1.5 Ma. The responses of wildfire activity to climate and vegetation changes were compared with other obtained environmental indices such as magnetic susceptibility, pollen in the terrestrial basin core (the PL02 core), and δ18O in the marine core (LR04). The results confirmed that macro-charcoal records are an effective and sensitive indicator of environmental evolution in arid and semi-arid areas. The peak values of charcoal concentration and charcoal flux generally occurred during climate transition periods, especially in the transition period from humid to drought conditions (specifically in the MIS41-MIS40, MIS39-MIS38, MIS19-MIS18, MIS17-MIS16, MIS15-MIS14, MIS11-MIS10, MIS9-MIS8, and MIS3-MIS2 time intervals). Furthermore, we found that the biomass burned in wildfires (i.e., the high biomass burned as indicated by the peak levels of charcoal concentration) was controlled by the amount of vegetation, while the occurrence of wildfires was related to climate fluctuations. In addition, some Milankovitch cycles (such as 100-ka cycles, 40-ka cycles, and 20-ka cycles) were evident in the charcoal records, thus indicating that the main driving force of wildfire activity in the Yinchuan Basin was climate change caused by variations in the Earth's orbit. Among these, the 40-ka cycles disappeared after 0.72 Ma, accompanied by changes in wildfire activity characteristics. We also discovered that the 400-ka cycles were stable throughout time. This study provides reliable evidence for some remarkable climate events, including the Mid-Pleistocene Transition (MPT) and the Mid-Brunhes Event (MBE), from the charcoal records in the Yinchuan Basin (an arid and semi-arid region in the mid-latitudes of the Northern Hemisphere). • Wildfire evolution and its response to climate change were examined in the Yinchuan Basin during the past 1.5 Ma. • The driving force of fire activity is climate change caused by variations in the Earth's orbit. • The characteristics of fire activity are influenced by vegetation and climate change. • Intense fire activity occurs during climate transition periods. • Some remarkable climate events (i.e., the MPT and MBE) are reflected in the fire activity. [ABSTRACT FROM AUTHOR]