volume size distribution of microparticles in ice cores from the tibetan plateau the volume distribution of atmospheric dust particles microparticles of 1 30 mm diameter in muztagata dunde dasuopu and everest ice cores from the tibetan plateau was measured and fitted as a log normal function in order to characterize their basic size properties our results reveal that whether the volume distribution fits the log normal function or not largely depends on the dust concentration and the specific dust storm event but is independent of physiographical location and season our results show only high concentration samples obey the log normal distribution in volume with mode sizes ranging from 3 to 16 mm the log normal distribution was largely attributed to the mid sized particles between 3 and 15 mm which contribute most 70 of the total volume the volume size distribution characteristics for mineral dust particles from ice cores reveal that the coarse particles might be common in the upper level troposphere over the tibetan plateau these dust size features are useful to advance our understanding of dust effects on climate and provide clues to better characterize atmospheric dynamics over the tibetan plateau that will help to improve the current models

wet climate during the little ice age in the arid tarim basin northwestern china a relatively cold period the little ice age lia just prior to the current warm period has been documented from many regions of the globe however hydrological changes wet dry conditions during the lia appear to be very different across different climatic regimes suggesting that the position strength and or pattern of atmospheric circulation could have changed significantly in the past therefore paleohydrological studies may have some implications for potential future hydrological changes in an anticipated warming world in this study we investigated hydrological changes over the last 800 years in the arid tarim basin northwestern china we used carbon isotopes of plant remains mainly leaves from a 10 5 m long aeolian sand sediment section to evaluate changes in dry wet conditions the average value of carbon isotopes of plant remains during the lia period ad 1490 to 1890 is 26 0 ranging from 28 2 to 23 6 much lower than values before average of 24 3 from 25 5 to 22 4

late quaternary palaeoenvironment change and landscape evolution along the keriya river xinjiang china the relationship between high mountain glaciation and landscape evolution in foreland desert regions abstract the sedimentology and geomorphology of landforms along keriya river that traverse the kunlun mountains and taklamakan desert were studied to examine the relationship between environmental change and landscape evolution in mountains and desert margins of the taklamakan desert the region is divided into four geomorphic provinces desert with active dunes and sand seas desert pediment with fans and foothills with deep gorges and glaciated mountains a succession of three fans with dunes is differentiated on the basis of morphostratigraphy and relative weathering the oldest fan and dunes are radiocarbon dated to 29 ka this fan probably formed as a response to increased meltwater and sediment loads as glaciers retreated at the end of the local last glacial maximum in the kunlun mountains periglacial and glacial features throughout the region show that during the last glacial the snowline was lowered to 4000 m a s l permafrost existed down to an altitude of 1800 m a s l and that the likely temperature depression was 10 c radiocarbon dates on sand dunes and tamarisk hills help define the age of the lower two terraces to 1 5 ka and a few hundred years bp this suggests that these terraces may have formed in response to increased precipitation during more humid times at 2 ka and during the little ice age respectively the landforms and sediments in this region are polygenetic in origin being transported eroded and deposited by glacial fluvial aeolian and lacustrine processes particle size characteristics show that the fluvial sediments were substantially modified down basin in contrast the aeolian sediments were modified as they were transported toward the mountains from the desert by the dominant northerly winds this complex interaction between environmental change and earth surface processes provides an important framework for examining the environmental consequences of the recently growing population and intensified agricultural activities along the mountain and desert margins of the taklamakan desert

holocene glacier variability and neoglacial hydroclimate at alfotbreen western norway abstract glaciers and small ice caps respond rapidly to climate perturbations mainly winter precipitation and summer temperature and the mass balance of glaciers located in western norway is governed mainly by winter precipitation pw records of past pw can offer important insight into long term changes in atmospheric circulation but few proxies are able to accurately capture winter climate variations in scandinavia reconstructions of equilibrium line altitude ela variations from glaciers that are sensitive to changes in pw therefore provide a unique opportunity to quantify past winter climate in this region here we present a new holocene glacier activity reconstruction for the maritime ice cap alfotbreen in western norway based on investigations of distal glacier fed lake sediments and modern mass balance measurements 1963 2010 several lake sediment cores have been subject to a suite of laboratory analyses including measurements of physical parameters such as dry bulk density dbd and loss on ignition loi geochemistry xrf surface magnetic susceptibility ms and grain size distribution to identify glacial sedimentation in the lake both radiocarbon ams 14 c and 210 pb dating were applied to establish age depth relationships in the sediment cores a novel approach was used to calibrate the sedimentary record against a simple ela model which allowed reconstruction of continuous ela changes for alfotbreen during the neoglacial when alfotbreen was present i e the last 1400 years furthermore the resulting ela variations were combined with an independent summer temperature record to calculate neoglacial pw using the liestol equation the resulting pw record is of higher resolution than previous reconstructions from glaciers in norway and shows the potential of glacier records to provide high resolution data reflecting past variations in hydroclimate complete deglaciation of the alfotbreen occurred 9700 cal yr bp and the ice cap was subsequently absent or very small until a short lived glacier event is seen in the lake sediments 8200 cal yr bp the ice cap was most likely completely melted until a new glacier event occurred around 5300 cal yr bp coeval with the onset of the neoglacial at several other glaciers in southwestern norway alfotbreen was thereafter absent or very small until the onset of the neoglacial period 1400 cal yr bp the little ice age lia 650 50 cal yr bp was the largest glacier advance of alfotbreen since deglaciation with a maximum extent at 400 200 cal yr bp when the ela was lowered approximately 200 m relative to today the late onset of the neoglacial at alfotbreen is suggested to be a result of its low altitude relative to the regional ela a synthesis of neoglacial ela fluctuations along the coast of norway indicates a time transgressive trend in the maximum extent of the lia which apparently seems to have occurred progressively later as we move northwards we suggest that this trend is likely due to regional winter precipitation differences along the coast of norway

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

timing and climate forcing of volcanic eruptions for the past 2 500 years volcanic eruptions contribute to climate variability but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual to decadal temperature variability in the northern hemisphere during the past 2 500 years our results are based on new records of atmospheric aerosol loading developed from high resolution multi parameter measurements from an array of greenland and antarctic ice cores as well as distinctive age markers to constrain chronologies overall cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth century pandemics famines and socioeconomic disruptions in eurasia and mesoamerica while allowing multi millennium quantification of climate response to volcanic forcing

late holocene forcing of the asian winter and summer monsoon as evidenced by proxy records from the northern qinghai tibetan plateau abstract little is known about decadal to centennial scale climate variability and its associated forcing mechanisms on the qinghai tibetan plateau a decadal resolution record of total organic carbon toc and grainsize retrieved from a composite piston core from kusai lake nw china provides solid evidence for decadal to centennial scale asian monsoon variability for the northern qinghai tibetan plateau during the last 3770 yr intensified winter and summer monsoons are well correlated with respective reductions and increases in solar irradiance a number of intensified asian winter monsoon phases are potentially correlated with north atlantic climatic variations including bond events 0 to 2 and more recent subtle climate changes from the medieval warm period to the little ice age our findings indicate that asian monsoon changes during the late holocene are forced by changes in both solar output and oceanic atmospheric circulation patterns our results demonstrate that these forcing mechanisms operate not only in low latitudes but also in mid latitude regions the northern qinghai tibetan plateau

late holocene hydroclimatic variation in central asia and its response to mid latitude westerlies and solar irradiance abstract hydroclimatic variations in central asia are widely recognized to be tele connected with the north atlantic climate via the mid latitude westerlies however the long term hydroclimatic variation and its response to north atlantic climate changes are not fully understood here we report multi decadal and centennial hydroclimatic variations in central asia during the late holocene using high resolution oxygen and carbon isotopes of bulk carbonate from a remote hydrologically closed alpine lake in tianshan mountains northwestern china the hydroclimatic variations inferred from the covariance between 18ocarb and 13ccarb and published multi proxy in the lake sayram together agree well with the records from the central asia showing enhanced effective moisture at the intervals of 4000 3780 3590 3210 2800 2160 1700 1370 and 890 280 cal yr bp during the negative phase of north atlantic oscillation nao comparison with european hydroclimatic changes on centennial scale our records not only provide valuable insight into the hydroclimatic variations in central asia but also indicate all broadly contemporaneous changes with that of southern europe whereas antiphase with that of northern europe we then conclude that the observed antiphase hydroclimatic pattern between northern europe and southern europe central asia on centennial time scale during the late holocene were persistently controlled by the north south migration of mid latitude westerlies and changes of nao phase in response to solar irradiance forcing however further research is necessary to fully disentangle the natural and anthropogenic forcing mechanisms for enhanced effect moisture and or precipitation in central asia

a pollen record of holocene climatic changes from the dunde ice cap qinghai tibetan plateau pollen preserved in ice cores from the dunde ice cap provides a sensitive record of holocene climatic changes and vegetational response in the northern qinghai tibetan plateau at time scales ranging from millennia to centuries and decades pollen analysis of the annually resolvable ice layers for a 30 yr period 1957 1986 suggests that total pollen concentration is correlated positively with summer precipitation and negatively with summer temperature thus it is a sensitive indicator of moisture availability and vegetation density in the steppe and desert regions around dunde high pollen concentrations between 10 000 and 4800 yr b p suggest that the summer monsoon probably extended beyond its present limit to reach dunde and westernmost tibet in response to orbital forcing the summer monsoon retreated time transgressively across the qinghai tibetan plateau during the middle holocene relatively humid periods occurred at 2700 2200 1500 800 and 600 80 yr b p probably as a result of neoglacial cooling prominent pollen changes during the medieval warm period 790 620 yr b p and the little ice age 330 80 yr b p suggest that the vegetation in the qinghai tibetan plateau region is sensitive to abrupt century scale climatic changes such as those anticipated in scenarios of greenhouse warming

a 700 year history of groundwater recharge in the drylands of nw china a 700 year semi quantitative history of diffuse groundwater recharge in the badain jaran desert inner mongolia is proposed on the basis of solute data from multiple unsaturated zone groundwater profiles using mass balance of chloride to establish recharge rates and profile chronologies four relatively humid 1330 1430 1500 1620 1700 1780 and 1950 1990 and three relatively arid phases 1430 1500 1620 1700 and 1900 1950 are discernable across the profiles the recharge history broadly reflects multidecadal to centurial timescale precipitation changes in the northern tibetan plateau and suggests that variations in east asian summer monsoon intensity affect desert recharge rates uncertainties in the records owing to assumptions about the cl inputs are examined by comparing deterministic and stochastic cl input scenarios such records are valuable for assessing spatial aspects of climate changes in the region as well as for informing sustainable water resource management strategies for northwestern china s drylands

climate changes reconstructed from a glacial lake in high central asia over the past two millennia abstract climatic changes in arid central asia aca over the past two millennia have been widely concerned however less attention has been paid to those in the high central asia hca where the asian water tower nurtures the numerous oases by glacier and or snow melt here we present a new reconstruction of the temperature and precipitation change over the past two millennia based on grain size of a well dated glacial lake sediment core in the central of southern tianshan mountains the results show that the glacial lake catchment has experienced cold wet climate conditions during the dark age cold period 300 600 ad dacp and the little ice age 1300 1870 ad lia whereas warm dry conditions during the medieval warm period 700 1270 ad mwp integration of our results with those of previously published lake sediment records stalagmite 18o records ice core net accumulation rates tree ring based temperature reconstructions and mountain glacier activities suggest that there has a broadly similar hydroclimatic pattern over the hca areas on centennial time scale during the past two millennia comparison between hydroclimatic pattern of the hca and that of the aca areas suggests a prevailing warm dry and cold wet hydroclimatic pattern over the whole westerlies dominated central asia areas during the past two millennia we argue that the position and intensity of the westerlies which are closely related to the phase of the north atlantic oscillation nao and the strength of the siberian high pressure sh could have jointly modulated the late holocene central asia hydroclimatic changes

substantial glacier mass loss in the tien shan over the past 50 years long term changes of the mountain glaciers in the tien shan central asia are not well constrained remote sensing data and glaciological models reveal a 27 decline of glacier mass from 1961 to 2012 linked to increased summer melting

1300 years of climatic history for western central asia inferred from tree rings more than 200 000 ring width measurements from 384 trees were obtained for 20 individual sites ranging from the lower to upper local timber lines in the northwest karakorum of pakistan and the southern tien shan of kirghizia samples were obtained predominantly from juniper species juniperus and were analysed to reconstruct regional climatic variation patterns in western central asia since ad 618 site distri bution represents diverse ecological conditions e g combinations of temperature and moisture stress within the karakorum and tien shan mountains permitting both intra montane and inter montane comparisons of chronologies three different types of chronologies ree ecting interannual decadal and centennial scale ring width variations were calculated a statistic skeleton plotting technique was used to identify ring width pointer years interannual a 101 year kernel e lter was used to identify decadal scale variations and for a subset of long lived trees the mean ring width of the entire single series was used to identify centennial trends after extracting and calibrating each of these three distinct wavelengths in ring width variation the results were combined into a comprehensive reconstruction ree ecting primarily temperature e uctuations in western central asia since ad 618 the nature and the temporally changing strength of the climatic signals of this reconstruction are discussed in detail a maximum latewood density record of pinus tienschanica from central tien shan was used as a predictor series to calibrate and validate tree ring width variation in so doing we link our results to the circumpolar maximum latewood density network briffa et al 1998a 1998b schweingruber and briffa 1996

glacier fluctuations of muztagh ata and temperature changes during the late holocene in westernmost tibetan plateau based on glaciolacustrine sediment records late holocene glacier variations in westernmost tibetan plateau were studied based on the analysis of grain size magnetic susceptibility and elements from an 8 3 m long distal glaciolacustrine sediment core of kalakuli lake our results show that there are four glacier expansion episodes occurring in 4200 3700 calibrated years cal years b p 2950 2300 cal years b p 1700 1070 cal years b p and 570 100 cal years b p and four glacier retreat periods of 3700 2950 cal years b p 2300 1700 cal years b p 1070 570 cal years b p and 50 cal years b p present the four glacier expansion episodes are generally in agreement with the glacier activities indicted by the moraines at muztagh ata and kongur shan as well as with the late holocene ice rafting events in the north atlantic over the last 2000 years our reconstructed glacier variations are in temporal agreement with reconstructed temperature from china and the northern hemisphere indicating that glacier variations at centennial time scales are very sensitive to temperature in western tibetan plateau

the size distribution of microparticles from selected segments of the greenland ice core project ice core representing different climatic periods the size distribution of insoluble microparticles dust in the particle size interval 0 4 6 0 m radius has been measured in more than 1400 samples from the greenland ice core project grip deep ice core from summit greenland the samples were taken from ice core segments representing 32 climatic periods including ice from the eem interglacial and ice from below the eemian ice the mean dust volume distributions from the climatic periods are compared and the relationship of total dust mass to the concentration of ca2 and to the stable isotopic composition 18o is investigated the dust volume distributions are found to be lognormal in the size interval 0 4 2 0 m with nearly identical shapes changes of the lognormal part of the volume distributions are found to be connected to the total dust mass in a systematic way the total dust mass is correlated to the ca2 concentration and data do not show any enrichment in ca2 from exposed continental shelves due to lower sea levels during the last glacial maximum the total dust mass is strongly connected to 18o the volume distribution of the particles in the size interval 2 0 6 0 m is found to be almost the same in most periods the exceptions are the cold periods in the last part of the last glacial period where the volume of these particles is higher than in most periods and the periods from the eemian and just above the eemian where the volume of these particles is lower the volume distributions of both the eemian warm periods and the cold eemian events are different from the distributions in ice from both below and above the eemian ice climate changes appear to have modified the processes of production transport modification and deposition of the dust aerosol in the same way over the last 120 000 years or more

a 2540 year record of moisture variations derived from lacustrine sediment sasikul lake on the pamir plateau although the pamir plateau is an ideal place to investigate paleo environmental changes in the westerlies dominated high central asia there are only few holocene records from this region we present a sub centennially resolved lacustrine record of moisture variations from sasikul lake central pamir plateau based on geochemical sedimentological and mineralogical proxies our results show that generally dry conditions at sasikul lake during the past 2540 years were interrupted by a pronounced wet period between ad 1550 and 1900 corresponding to the little ice age lia more negative values of carbonate 18o lower total inorganic carbon tic and sand content during the lia all indicate a relatively wet period with higher lake level higher tic during the medieval warm period mwp ad 950 1200 reveals a lower lake level relative to the lia low 18o during this time is probably attributed to changes in the isotopic composition of input water and or upstream moisture sources the significant incr

dust deposition in the aral sea implications for changes in atmospheric circulation in central asia during the past 2000 years we investigated mineral aerosol dust deposition in the aral sea with intention to understand the variability of dust in central asia and its implications for atmospheric circulation change in the late holocene using an 11 12 m sediment core of the lake we calculated bulk sediment fluxes at high time resolution and analyzed grain size distributions of detrital sediments a refined age depth model was established by combined methods of radiocarbon dating and archeological evidence besides a principal component analysis pca of grain size fractions and elements fe ti k ca sr was used to assess the potential processes controlling detrital inputs the results suggest that two processes are mainly relevant for the clastic input as the medium silt fractions and ti fe and k are positively correlated with component 1 c1 and the fine size fractions 6 mm are positively correlated with component 2 c2 taking the results of the pca geological backgrounds clastic input processes into account we propose that the medium silt fractions and in particular the grain size fraction ratio 6e32 mm 2e6 mm can serve as indicators of the variability of airborne dust in the aral sea region on the contrary the fine size fractions appear to be contributed mainly by the sheetwash processes the bulk sediment deposition fluxes were extremely high during the little ice age lia ad 1400e1780 which may be related to the increased dust deposition as indicated by the variations of grain size ratio and ti the history of dust deposition in central asia can be divided into five distinct periods with a remarkably low deposition during ad 1e350 a moderately high value from ad 350e720 a return to relatively low level between ad 720 and ad 1400 including the medieval warm period mwp ad 755e1070 an exceptionally high deposition from ad 1400 to 1940s and an abnormally low value since 1940s the temporal variations in the dust deposition are consistent with the changes in the siberian high sh and mean atmospheric temperature of the northern hemisphere during the past 2000 years with low high annual temperature anomalies corresponding to high low dust supplies in the aral sea sediments respectively the variations in the fine size fraction also show a broadly similarity to a lacustrine d

assessing the ratio of archaeol to caldarchaeol as a salinity proxy in highland lakes on the northeastern qinghai tibetan plateau abstract the ratio of archaeol to caldarchaeol the ace index has been proposed recently as an index for paleosalinity reconstruction and is based principally on archaeal core lipids cls from coastal salt pans turich c freeman k h 2011 archaeal lipids record paleosalinity in hypersaline systems organic geochemistry 42 1147 1157 we have examined possible relationships between salinity and ace in both cls and intact polar lipids ipls from suspended particulate matter spm and surface sediments of lakes and surrounding soils on the northeastern qinghai tibetan plateau our results showed that ace values were positively correlated with salinity in all samples however cl ace values were systematically higher than ipl ace values probably due to different degradation kinetics of intact polar ip archaeol and ip caldarchaeol on the other hand surface sediment ace values from both cls and ipls were lower than spm ace values probably due to enhanced production of caldarchaeol relative to archaeol in the sediment our results demonstrate that the ace proxy reflects changes in salinity in diverse environments on the qinghai tibetan plateau which is promising for paleosalinity reconstruction however caution should be used when applying the salinity proxy before we have a better understanding of degradation kinetics of archaeal ipls and in situ production of caldarchaeol and archaeol in sediments

hydroclimatic changes in china and surroundings during the medieval climate anomaly and little ice age spatial patterns and possible mechanisms abstract investigating hydroclimatic changes during key periods such as the medieval climate anomaly mca 1000 1300 ad and the little ice age lia 1400 1900 ad is of fundamental importance for quantifying the responses of precipitation to greenhouse gas induced warming on regional and global scales this study synthesizes the most up to date and comprehensive proxy moisture precipitation records during the past 1000 years in china and surroundings the proxy data collected include 34 records from arid central asia aca and 37 records from monsoonal asia our results demonstrate a pattern of generally coherent regional moisture variations during the mca and lia in mid latitude asia north of 30 n monsoonal northern china north china and northeast china was generally wetter while aca northwest china and central asia was generally drier during the mca than in the lia a west east mode the boundary between wetter northern china and drier aca was roughly consistent with the modern summer monsoon boundary in monsoonal china to the east of 105 e the northern part was generally wetter while the southern part was generally drier during the mca than in the lia a north south mode with a boundary roughly along the huai river at about 34 n these spatial patterns of moisture precipitation variations are also identified by instrumental data during the past 50 years in order to understand the possible mechanisms related to the moisture variations during the mca and lia we investigate the major sst and atmospheric modes e g the el nino southern oscillation enso the atlantic multidecadal oscillation amo and the north atlantic oscillation nao which affect the moisture precipitation variations in the study region using both the instrumental data and the reconstructed time series it is found that the enso may play an important role in determining hydroclimatic variability over china and surroundings on a multi centennial time scale and that the foregoing spatial patterns could be attributed to the la nina like el nino like condition during the mca lia in addition amo and nao may also have their own contributions

solar forced 2600 bp and little ice age highstands of the caspian sea abstract the level of the caspian sea the largest inland sea in the world has fluctuated capriciously in history with amplitudes up to 3 m in the last century to 25 m in the last millennium and to over 150 m since the last glacial there is little consensus about the causes and forecasts are contradictory mainly due to a lack of solid data about past sea levels before 1837 ad when instrumental observation started we studied the holocene turali barrier complex along the western caspian shore in dagestan russia barrier dynamics during the last 3 m sea level cycle in the past century show that only lagoonal deposits overridden by highstand barriers are suitable for dating former highstands in the holocene barrier complex we selected the most suitable sites for dating using ground penetrating radar gpr profiles outcrops and gravel pits we obtained 14 accelerator mass spectrometry ams 14c data on in situ double valved molluscs from highstand lagoonal deposits the results suggest that the last major highstands occurred around 2600 bp and in the little ice age and coincide with global cooling events associated with minima in solar activity this suggests that millennial precipitation changes in the volga river drainage basin are also forced by solar activity

testing the model for linking grain size component to lake level status of modern clastic lakes a model was proposed recently for linking grain size component to lake level status based on investigations of daihai lake in inner mongolia to test this model grain size components of the surface sediments of dali lake 500 km northeast of daihai lake were partitioned and their relationships with the lake level status were examined in this study the data show that modern clastic sediments of dali lake contain five distinct grain size components representing specific depositional processes and sedimentary environments within the lake in common with daihai lake these components are specified as long term suspension clay offshore suspension fine silt offshore suspension medium to coarse silt nearshore suspension fine sand and nearshore saltation medium sand in dali lake by contrast the offshore suspension components are lacking in more samples from the nearshore zone the nearshore suspension and saltation components occur in more samples from the offshore and transitional zone respectively and two adjacent components are well separated these differences would result from higher energy hydraulics of dali lake generated by stronger and more frequent winds occurring in the lake region under this hydraulic condition clastic materials entering the lake and the resultant components would be reworked more seriously during transportation within the lake leading to further basin ward transportations of the major components and better separations of two adjacent components percentage of the nearshore components is negatively related to water depth suggesting the grain size component lake level status model for the lake this model was applied to a sediment core from the lake showing that high percentages of the nearshore components in the core coincide with low precipitations reconstructed on the pollen profile of the same core the coincidence of two independent proxies demonstrates the wide applicability of the grain size component lake level status model to lake s paleohydrological reconstruction

hydrographic development of the aral sea during the last 2000 years based on a quantitative analysis of dinoflagellate cysts the aral sea basin is a critical area for studying the influence of climate and anthropogenic impact on the development of hydrographic conditions in an endorheic basin we present organic walled dinoflagellate cyst analyses with a sampling resolution of 15 to 20 years from a core retrieved at chernyshov bay in the nw large aral sea kazakhstan cysts are present throughout but species richness is low seven taxa the dominant morphotypes are lingulodinium machaerophorum with varied process length and impagidinium caspienense a species recently described from the caspian sea subordinate species are caspidinium rugosum romanodinium areolatum spiniferites cruciformis cysts of pentapharsodinium dalei and round brownish protoperidiniacean cysts the chlorococcalean algae botryococcus and pediastrum are taken to represent freshwater inflow into the aral sea the data are used to reconstruct salinity as expressed in lake level changes during the past 2000 years we quantify and date for the first time prominent salinity variations from the northern part of the large aral sea during high lake levels i caspienense representing brackish conditions with salinities of about 10 15 g kg or less prevails assemblages dominated by l machaerophorum document lake lowstands during approximately 0 425 ad or 100 bc 425 ad 920 1230 ad 1500 ad 1600 1650 ad 1800 ad and since the 1960s because salinity in the aral sea is mostly controlled by meltwater discharges from the syr darya and amu darya rivers we interpret changes in salinity levels as a proxy for temperature fluctuations in the tien shan mountains that control snow melt significant erosion of marine palaeogene and neogene deposits in the hinterland evidenced between 1230 ad and 1400 ad is regarded as sheet wash from shore this is controlled by the low pressure system that develops over the eastern mediterranean and brings moist air to the middle east and central asia during late spring and summer we propose that the recorded environmental changes are related primarily to climate but perhaps to a lesser extent by humancontrolled irrigation activities our results documenting climate change in western central asia are fairly consistent with reports elsewhere from central asia

persistent positive north atlantic oscillation mode dominated the medieval climate anomaly the medieval climate anomaly mca was the most recent pre industrial era warm interval of european climate yet its driving mechanisms remain uncertain we present here a 947 year long multidecadal north atlantic oscillation nao reconstruction and find a persistent positive nao during the mca supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker nao conditions into the little ice age lia globally distributed proxy data suggest that this nao shift is one aspect of a global mca lia climate transition that probably was coupled to prevailing la nina like conditions amplified by an intensified atlantic meridional overturning circulation during the mca

evaluating the timing of former glacier expansions in the tian shan a key step towards robust spatial correlations the timing of past glaciation across the tian shan provides a proxy for past climate change in this critical area correlating glacial stages across the region is difficult but cosmogenic exposure

a 1000 year climate ice core record from the guliya ice cap china its relationship to global climate variability in 1992 an american chinese expedition successfully recovered three ice cores 308 6 93 2 and 34 5m from the guliya ice cap summit 6710 m a s l in the far western kunlun on the qinghai tibetan plateau china guliya resembles a polar icecap with 10 m 200 m and basal temperatures of 15 6 5 9 and 2 1 c respectively the 308 6 m core to bedrock is the longest ice core retrieved from an elevation greater than 4000 m a s l and provides the first ice core history from the western side of the qinghai plateau the plateau experiences a pronounced annual precipitation cycle during which 70 80 of annual total precipitation falls in the summer monsoon season this leads to a marked visible stratigraphy in the glaciers which allows accurate dating of the ice cores and reconstruction of the net mass accumulation this paper presents 1 the results of the geophysical program to determine ice thickness ice flow and surface topography 2 an assessment of net accumulation from stake measurements snow pits and shallow core samples and 3 the analyses of the upper 100 m of the 308 6 m core which provide a 1000 year history including the little ice age which is compared with chinese historical records extended periods of positive accumulation on guliya are closely contemporaneous with dry periods in eastern china a trans pacific teleconnection is suggested by the strong temporal coherence between extended wet and dry phases on guliya and on the quelccaya ice cap peru

glacial activity reflected in a continuous lacustrine record since the early holocene from the proglacial laigu lake on the southeastern tibetan plateau abstract the southeastern tibetan plateau is an important area of monsoonal maritime glaciation and it serves as a watershed for several major asian rivers including the brahmaputra river and the lantsang river glacial activity is sensitive to climate change in this area however due to high annual ablation and accumulation in this region ice cores over long time scales are difficult to retrieve in addition reconstructed glacial activity from moraine dates is usually discontinuous here we use a sediment core retrieved from laigu lake which is a proglacial lake located in the headwaters of the parlung zangbo river the largest tributary of the brahmaputra river to reflect glacial activities over the last 8000 years in this area samples of the sediment core were analyzed for magnetic susceptibility xrf x ray florescence scanned elemental concentration and grain size the results indicated that the magnetic susceptibility and cps peak area counts per second of strontium sr could be used as proxies for glacial activity the cps of sr and the magnetic susceptibility were lower and the glacial activity was weak before 4 3 cal ka bp expansion of the glaciers in this area began from 4 3 cal ka bp and continued to develop after 3 3 cal ka bp from 2 2 cal ka bp to 1 6 cal ka bp the glaciers retreated substantially followed by another development period until the onset of modern global warming based on our findings and other climate records we concluded that glacial activity in the southeastern tibetan plateau areas was mainly influenced by northern hemisphere temperatures and summer insolation over a sub orbital time scale but did not respond to the indian monsoon

late holocene climatic and environmental changes in arid central asia abstract late holocene climate and environmental changes in arid central asia were analyzed using various paleoclimate archives such as ice cores tree rings lake sediments historical documents glacial fluctuations and archeological data over the last 2000 years arid central asia witnessed three humid periods from ad 0 410 650 890 and 1500 1820s dry periods occurred in 420 660 and in 900 1510s concerning temperature the most striking features are the existence of the medieval warm period mwp and the little ice age lia the mwp was recorded in the 9 12th centuries and was accompanied by an anomalously dry climate whereas the lia extended from the 15 18th centuries and was accompanied by pluvial conditions temperature and precipitation show significantly negative correlations on annual decadal and centennial timescales temperature was generally above average when dry climate conditions predominated on decadal to centennial timescales during the last 1000 years the coldest decades of the last millennium the period 1630 1650s matched with an anomalously wet episode the combination of paleoclimatic evidence clearly suggests that the combination of cold and wet climate condition during the lia was responsible for the strong glacial advances in several mountain systems of central asia

solar forcing of north atlantic surface temperature and salinity over the past millennium there were several centennial scale fluctuations in the climate and oceanography of the north atlantic region over the past 1 000 years including a period of relative cooling from about ad 1450 to 1850 known as the little ice age1 these variations may be linked to changes in solar irradiance amplified through feedbacks including the atlantic meridional overturning circulation2 changes in the return limb of the atlantic meridional overturning circulation are reflected in water properties at the base of the mixed layer south of iceland here we reconstruct thermocline temperature and salinity in this region from ad 818 to 1780 using paired 18o and mg ca ratio measurements of foraminifer shells from a subdecadally resolved marine sediment core the reconstructed centennial scale variations in hydrography correlate with variability in total solar irradiance we find a similar correlation in a simulation of climate over the past 1 000 years we infer that the hydrographic changes probably reflect variability in the strength of the subpolar gyre associated with changes in atmospheric circulation specifically in the simulation low solar irradiance promotes the development of frequent and persistent atmospheric blocking events in which a quasi stationary high pressure system in the eastern north atlantic modifies the flow of the westerly winds we conclude that this process could have contributed to the consecutive cold winters documented in europe during the little ice age

late holocene indian summer monsoon variations recorded at lake erhai southwestern china in this study we report changes in indian summer monsoon ism intensity during the past 3500 yr inferred from proxy indices at lake erhai southwestern china both the pollen concentrations and other proxy indices including sediment grain size total organic carbon contents toc and elemental contents e g fe al clearly indicate a long term decreasing trend in ism intensity over the late holocene during the period from approximately ad 750 to ad 1200 pollen concentrations of conifer and broadleaf trees and herbs reached the lowest levels over the past 3500 yr while the pollen percentages of both herbs and broadleaf trees increased suggesting a significant medieval drought the grain size toc and elemental contents also support an arid climate during the medieval period the little ice age lia at lake erhai was characterized as cold and wet the medieval and lia climatic patterns at lake erhai were similar to those over most of the ism areas but anti phase with those over east asian summer monsoon easm areas we suspect that sea surface temperature variations in the indo pacific oceans and the related land sea thermal contrasts may be responsible for such hydroclimatic differences between easm and ism areas

post deposition diffusion of 137cs in lake sediment implications for radiocaesium dating peak activities of radiocaesium 137cs in lake sediments have frequently been used to infer the ages of sediments deposited in the 1960s 137cs derived from nuclear bomb testing or in 1986 chernobyl derived 137cs records of the vertical distribution of 137cs in sediments can thus be used to provide accurate dates for a critical period in which palaeoecological reconstructions often overlap contemporary monitoring data however knowledge regarding how the distribution of 137cs in sediments is affected by post depositional processes is limited to interpretations based on the 137cs distribution in sediments sampled at a single given date this study assesses the extent to which the 137cs record in annually laminated varved lake sediments is affected by post depositional diffusion using 11 archived sediment cores sampled between 1986 and 2007 the sediment record reveals how chernobyl 137cs incorporated into the 1986 varve diffused downwards in the core at a decreasing rate over time whereas the surface sediments continued to receive inputs of 137cs mobilized from the catchment soils or lake margin in spite of these processes all cores post dating the chernobyl accident had a clear and well resolved peak in the 1986 varve justifying the use of this feature as a fixed chronostratigraphic feature because of the very high levels of chernobyl fallout at this site downwards migration of chernobyl 137cs has however completely masked the nuclear weapons 137cs fallout peak that had been clearly preserved in the 1964 varve of a pre chernobyl core sampled just three weeks before the chernobyl accident in consequence the weapons fallout marker is likely to be of little use for determining 137cs dates in areas strongly affected by high levels of chernobyl fallout

waves of accelerated motion in a glacier approaching surge the mini surges of variegated glacier alaska u s a periods of dramatically accelerated motion in which the flow velocity increases suddenly from about 55 cm d to a peak of 100 300 cm d and then decreases gradually over the course of a day occurred repeatedly during june and july 1978 81 in variegated glacier alaska a surging type glacier that surged in 1982 83 these mini surges appear to be related mechanistically to the main surge the flow velocity peak propagates down glacier as a wave at a speed of about 0 3 km h over a reach of about 6 km in length it is accompanied by a propagating pressure wave in the basal water system of the glacier in which after a preliminary drop the pressure rises rapidly to a level greater than the ice overburden pressure at the glacier bed and then drops gradually over a period of 1 2 d usually reaching a new low for the summer the peak velocity is accompanied by a peak of high seismic activity due to widespread fresh crevassing it is also accompanied by a rapid uplift of the glacier surface amounting to 6 11 cm which then relaxes over a period of 1 2 d maximum uplift rate coincides with the peak in flow velocity the peak in accumulated uplift lags behind the velocity peak by 2 h the uplift is mainly due to basal cavitation driven by the high basal water pressure although the strain wave associated with the mini surge motion can also contribute basal cavitation is probably responsible for the pulse of high turbidity that appears in the terminal outflow stream in association with each mini surge in the down glacier reach where the mini surge waves are attenuating the observed strain wave corresponds to what is expected for the propagating pulse in flow velocity but in the reach of maximum mini surge motion the strain wave has a form quite different possibly related to special features in the mini surge initiation process from that point up stream the flow acceleration in the mini surges is due to enhanced basal sliding caused by the high basal water pressure and the consequent reduction of bed friction a preliminary velocity increase shortly before the pressure wave arrives is caused by the forward shove that the main accelerated mass exerts on the ice ahead of it and the resulting preliminary basal cavitation causes the drop in water pressure shortly before the pressure wave arrives the mini surge wave propagation is controlled by the propagation of the water pressure wave in the basal water conduit system the propagation characteristics result from a longitudinal gradient up glacier increase in hydraulic conductivity of the basal water system in response to the up glacier increase of the basal water pressure in the mini surge wave the mini surge waves are initiated in a succession of areas situated generally progressively up glacier during the course of the summer season in these areas presumably melt water that has accumulated in subglacial reservoirs is released suddenly into the basal water system immediately below generating a pressure rise that propagates down stream from there relationships of the mini surges to the main surge are seen in the role of high basal water pressure in causing the rapid glacier motion in both phenomena in the pulse propagation features of both and in the high outflow turbidity associated with both the mini surges of variegated glacier have a strong resemblance to movement and uplift events observed in unteraargletscher and findelengletscher switzerland this bears on the question whether the mini surges are a particular characteristic of surge type glaciers prior to surge

synchronous fluctuations of glaciers in the alps and altai in the second half of the holocene the altai mountains occupy the northwestern part of the central asian collision belt the late holocene behavior of glaciers in the altai mountains was reconstructed for the khaidun river valley in the western part of the russian altai we report here 17 new radiocarbon datings from wood remains buried by moraines from peat layers and lacustrine sediments the glaciers advance took place in 2500 2200 bc 1100 bc 500 bc ad 400 ad 1200 1300 and ad 1500 1850 it is the first time that material which separates the so called historical stage of cooling into three stages has been collected in the altai mountains the comparison of time of moraine formation in the altai with glacier activity in the alps is evidence of the simultaneity of these processes

variability of the north atlantic oscillation over the past 5 200 years the north atlantic oscillation influences climate in the arctic region and northern europe reconstructions of circulation patterns associated with the north atlantic oscillation from a 5 200 year long lake sediment record suggest that the atmospheric circulation responded to significant transitions in northern hemisphere climate

climatic and hydrologic changes in the tien shan central asia abstract the authors analyze climatic and hydrologic data from 110 sites collected from the middle of the twentieth century to the present in the tien shan one of the largest mountain systems of central asia in spite of a few confounding interregional variations in the temporal changes of surface air temperature precipitation runoff glacier mass and snow thickness in the tien shan it has been possible to establish statistically significant long term trends in these key hydroclimatic variables the average rise in air temperature was 0 01 c yr 1 over the range with slightly lower values below 2000 m elevation the precipitation in the tien shan increased 1 2 mm yr 1 over the past half century the precipitation increase is larger at low altitudes in the northern and western regions than at altitudes above 2000 m a decrease in snow resources occurred almost everywhere in the tien shan the maximum snow thickness and snow duration have decreased on average 10 cm and 9 days respectively the annual

holocene environmental changes in lake bangong basin western tibet part 1 chronology and stable isotopes of carbonates of a holocene lacustrine core abstract a 12 4 m core collected from the eastern part of lake bangong is analyzed for mineralogy radiometric chronology and stable isotope contents of authigenic inorganic carbonate isotopic compositions of the modern lake waters and of its major tributaries are first presented radiocarbon activity of these waters show that equilibrium with the atmospheric co2 is not reached because of admixture of dead carbon in solution in the system a model is thus developed to correct the radiocarbon ages of fossil material of aquatic origin for this ageing the core provides a continuous holocene record changes in mineralogy of bulk sediments and in 13c and 18o contents of authigenic carbonates reveal extremely large changes in environmental conditions induced by climate changes and or local hydrological factors e g closure opening of the lake system controlled by the altitude of the outflow sill the eastern basin of lake bangong was closed before 9 6 and after 1 2 ka b p in response to aridity on the catchment wet warm conditions attributed to the monsoon influence were established suddenly at 9 6 ka b p and maintained until 6 2 ka b p although minor reversal events occurred between 8 6 and 7 7 ka b p the return towards aridity is non linear dry spells at 6 2 3 9 3 2 and 1 3 ka b p are alternated with short term periods with positive precipitation evaporation balance

a 1400 year high resolution record of atmospheric circulation over the north atlantic and asia major ion series developed from new subannual scale sampling of an ice core from central greenland are calibrated with instrumental series of atmospheric sea level pressure recording major marine icelandic low and terrestrial siberian high atmospheric circulation systems to provide proxy records of atmospheric circulation over the past 1400 years examination of the proxy records reveals major changes in behaviour of these systems c ad 1400 multidecadal and centennial scale periodic components characterization of mean sea level pressure anomaly fields during the little ice age and the mediaeval warm period the potential role of solar forcing coupled ocean atmosphere associations and a perspective within which the characteristics of instrumental era climate can be assessed

a high resolution 1200 year lacustrine record of glacier and climate fluctuations in lofoten northern norway here we present the first high resolution late holocene glacier record from the lofoten archipelago in northern norway the study is based on analyses of lacustrine sediments from the distal glacier fed lake kveitvikvatnet 30 1 m a s l as well as glacial geomorphological mapping of the 4 2 km2 surrounding catchment the lake sediment cores have been examined for input of glacial derived sediments by using physical geochemical and magnetic sediment properties including x ray fluorescence xrf magnetic susceptibility ms grain size analyses dry bulk density dbd and loss on ignition loi former glacier extent has been reconstructed using aerial photography and glacial geomorphological mapping lichenometric dating has been used to construct a moraine chronology covering the recent fluctuations of the largest glacier back to ad 1740 ams radiocarbon dating reveals that the lake sediment record covers the last 1200 years thereby including both the little ice age lia and the medieval cl

estimates of volcanic induced cooling in the northern hemisphere over the past 1 500 years explosive volcanism can alter global climate and hence trigger economic political and demographic change1 2 the climatic impact of the largest volcanic events has been assessed in numerous modelling studies and tree ring based hemispheric temperature reconstructions3 4 5 6 however volcanic surface cooling derived from climate model simulations is systematically much stronger than the cooling seen in tree ring based proxies suggesting that the proxies underestimate cooling7 8 and or the modelled forcing is unrealistically high9 here we present summer temperature reconstructions for the northern hemisphere from tree ring width and maximum latewood density over the past 1 500 years we also simulate the climate effects of two large eruptions in ad 1257 and 1815 using a climate model that accounts explicitly for self limiting aerosol microphysical processes3 10 our tree ring reconstructions show greater cooling than reconstructions with lower spatial coverage and based on tree ring width alone whereas our simulations show less cooling than previous simulations relying on poorly constrained eruption seasons and excluding nonlinear aerosol microphysics our tree ring reconstructions and climate simulations are in agreement with a mean northern hemisphere extra tropical summer cooling over land of 0 8 to 1 3 c for these eruptions this reconciliation of proxy and model evidence paves the way to improved assessment of the role of both past and future volcanism in climate forcing

late holocene glacier variations in the frontal and inner ranges of the tian shan central asia evidence for the timing and extent of late holocene glacial advances in the tian shan mountains central asia is based on lichenometric and radiocarbon dating of end moraines three phases of glacial advance occurred at 1700 2100 and 1100 1300 lichenometric l years ago and then during the little ice age 150 700 l years ago differences in the pattern of glacier variations between the northwestern frontal and inner areas of the tian shan are reflected in the equilibrium line altitude ela depression of 23 glaciers studied at nine selected sites the peripheral glaciers appear to have been significantly more extensive during late holocene advances than the glaciers of the inner areas this difference seems to be explained by regional differences in humidification in the northwestern periphery of the tian shan the cold periods of the late holocene were more humid than the warm period of the mid holocene whereas in the inner areas the pattern of climate changes was the opposite a warm and hu

characterizing the may 2015 karayaylak glacier surge in the eastern pamir plateau using remote sensing we investigate an internal surge of karayaylak glacier which was reported by the media in may 2015 to differentiate the may 2015 glacier surge from other glacier advances we surveyed changes in velocity crevasses and glacier area using landsat 8 oli l1t zy 1 02c and gaofen 1 images from october 2014 to july 2015 the velocity measured by automatic feature extraction and tracking during the active phase was 10 100 times the velocity during the quiescent phase with a maximum of 20 2 0 9 m d 1 mean standard error from 8 to 15 may 2015 in the west branch of the glacier the surge initiation and termination took place from 13 april to 16 june 2015 ice in the west branch length 7 km area 6 8 km 2 of karayaylak glacier accelerated down to the east branch leading to the development of crevasses and ice covering an additional 0 1 km 2 of summer pasture on the northwestern side however we detected no advance of the glacier s terminus

holocene glacier fluctuations and climate changes in the southeastern part of the russian altai south siberia based on a radiocarbon chronology abstract this study investigates glacier dynamic and climatic variations in the southeastern part of the russian altai se altai during the last 7000 years recent glacier retreats and ice melting in moraines has led to exhumation of organic material allowing the possibility of radiocarbon dating we report here 57 new radiocarbon dates from wood remains buried by moraines and from proglacial forefields from peat layers and lacustrine sediments that cover moraines from dead trees at the upper tree limit and from rock glaciers on trough slopes from six glacial valleys in the north chuya range se altai such a numerous dataset for the vast but unified in neotectonic and climatic conditions area is presented for the first time the history of research in the altai together with 62 previously published radiocarbon ages mainly of fossil soils and peat layers in the foot of the ranges in se altai they form the basis for understanding the relative magnitudes and timing of the most important glacial and climatic events of se altai new data refute the traditional concept of the russian altai holocene glaciations as a consecutive retreat of the late wurm glaciers and argue their complete degradation at the head of trough valleys at least 7000 cal years bp moraine complexes of three holocene glacial stages are morphologically expressed in trough valleys of the north chuya range they correlate with three identified periods of glacial advances from 4900 to 4200 cal years bp akkem stage from 2300 to 1700 cal years bp historical stage and in the 13th 19th centuries little ice age lia or aktru stage the coincident extremes of lowering temperature and increasing precipitation during the akkem stage led to abrupt glacier advances and forming of the most remote moraine complexes downstream in the valleys following glacier advances had distinctly smaller magnitudes in addition to the radiocarbon data the time limits of the historical stage were defined more precisely using dendrochronological and archaeological data from scythian burials of pazyryk culture in se altai repeated forest regrowth in the presently glaciatiated area indicates significant retreat or even complete glacier degradation during interstage warming the decreases of glacier length in the following stages argues for intensification of aridity in the se altai during the second half of the holocene the thermal minimum in the middle of 19th century the greatest in the last millennium did not positively influence the mass balance of glaciers which also supports this conclusion

late holocene variation of the raigorodskogo glacier and climate change in the pamir alai central asia during the late holocene the raigorodskogo glacier in the pamir alai central asia expanded before 3215 after 1545 and at 310 cal years bp as dated by the 14c calibrated ages of wood samples from moraine deposits and terrace exposures the glacier expansions which were accompanied by increased melt water run off over the terrace surface were confined to the proglacial area the terrace deposits with intercalated buried soil layers provide evidence of two obvious warm periods when the glacier abruptly retreated during the late holocene shortly before 1545 cal years bp and again sometime before ca 500 cal years bp fallen juniperus turkestanica broken by moraine deposits suggests that the largest glacial expansion during the little ice age occurred 310 cal years bp the glacier expansion in the little ice age was on roughly the same scale as that which occurred in the cold period after 1545 cal years bp observational records of the glacier terminus and moraine positions indicate that recent glacier advances occurred in the years 1908 1911 sometime in 1911 1934 and in 1960 1977 these advances were small while the glacier recessions were larger in the 1900s with large recessions also sometime in 1911 1934 and in 1977 1998 the glacier recession rate of 27 m year in 1911 1934 was faster than the rates of 13 m year in 1977 1990 and 21 m year in 1990 1998 however the glacier recession rate has been accelerating recently particularly after 1990 this recession reflects recent climate warming in inland asia

a model for linking grain size component to lake level status of a modern clastic lake abstract grain size distributions of fluvial eolian and marine sediments were explicated decades ago for lake sediments however there is still great uncertainty in explaining the genesis of grain size components due to the inherent complexity of their polymodal distributions in this study the grain size components of the surface sediments of daihai lake inner mongolia were partitioned using a lognormal distribution function and the relationship between the identity of each component and the specific sedimentary environment was investigated the data indicate that the modern clastic sediments of daihai lake contain five distinct unimodal grain size distributions representing five grain size components each of the components retains its identity including modal size manner of transportation and environment of deposition although the relative percentage varies with the hydraulic condition throughout the lake these components are specified from fine to coarse modes as long term suspension clay offshore suspension fine silt and medium to coarse silt and nearshore suspension fine sand and saltation medium sand the percentage of the components interpreted as an indication of nearshore environments displays a negative correlation with water depth across the modern lakebed suggesting a model for linking the nearshore components in sediment cores to the lake level status in the geological past the model was applied to a sediment core from the lake where high percentages of the nearshore components in the core sediments were correlated with low regional precipitations reconstructed on the pollen profile of the same core the coincidences between two independent proxies do not only demonstrate the validity of lognormal distribution function in partitioning polymodal sediments but also reveals the potential of the grain size component lake level status model for lake s paleohydrological reconstruction

modern hydrology and late holocene history of lake karakul eastern pamirs tajikistan a reconnaissance study abstract lake karakul in the pamirs tajikistan is a deep brackish water lake in a closed basin at almost 4000 m above sea level water samples from the catchment area and lake karakul and a 104 cm sediment core from its shallow eastern sub basin were investigated and provide a first lake record from the region spanning the last 4200 cal yr bp multi proxy analyses revealed the following a relatively high meltwater inflow from glaciers snow fields and frozen ground in the catchment as a result of relatively warm conditions was reconstructed for the period between 4200 and 3500 cal yr bp the shift to colder climatic conditions around 3500 cal yr bp was probably abrupt total organic carbon values displayed the most dramatic drop for the entire core within less than 40 years in contrast the subsequent re establishment of warmer conditions occurred gradually over several centuries a higher meltwater supply to the lake and warmer conditions were recorded since ca 1900 cal yr bp with two slightly colder intervals between 1200 and 800 cal yr bp and between 400 and 100 cal yr bp the abrupt shift to significantly colder and drier conditions around 3500 cal yr bp in the eastern pamirs is seen also in records from the aral sea and the guliya ice core from the western tibetan plateau however more palaeoclimate studies in this highly continental part of central asia are needed to assess the spatial and temporal patterns of the holocene climate in the region

how much do we really know about glacier surging some of the ideas about glacier surging are considered mainly but not entirely in the light of observations of temperate glaciers in alaska u s a made within the last 15 years climate has an influence on surge recurrence interval climate and weather also affect surge initiation termination and magnitude regional studies lead to the speculation that subglacial till plays a key role in surging and it has been found under all surge type glaciers studied so far including black rapids and variegated glaciers alaska in most of the glaciers studied till deformation processes dominate the motion in quiescence the linked cavity model of surge triggering and rapid motion is not consistent with these observations but the limited coverage of the observations does not rule it out under parts of the glaciers studied the till observations in alaska raise old questions about the interaction between till and the hydraulic systems of temperate glaciers the role of stored water which observations show to be active even in winter on black rapids glacier is noted

grain size in sediments from lake sugan a possible linkage to dust storm events at the northern margin of the qinghai tibetan plateau samples of surface deposits in the lake sugan catchment as well as surface lake sediments eolian materials occulted in the lake ice cover and airborne dust were collected for grain size analysis the results show that the coarse fraction of the lake sediments could be transported by ambient winds and to a lesser extent by river flow in the study area sediment cores were retrieved from lake sugan in december 2000 and 210pb and 137cs dating and grain size analyses were performed on these samples 210pb ages and the volume percentage of the fraction of lake sediments 63 m were used to reconstruct the dust storm history from 1957 to 2000 observational data for dust storm events collected at a local meteorological station largely agrees with the reconstructed trend for the past 44 years suggesting that lake sediments can be employed to trace the dust storm history of the northern qinghai tibetan plateau

soils as indicators of the pleistocene and holocene landscape evolution in the alay range kyrgystan abstract soils derived from quaternary glacial glaciofluvial and aeolian deposits in the alay range kyrgystan were studied to reconstruct the pleistocene and holocene landscape evolution geomorphologic studies radiocarbon dating of a horizons in palaeosols and iron fractionation were undertaken during the last glacial maximum lgm the abramov glacier in the alay range advanced down the koksu valley to an altitude of 2500 m asl about 50 km from the modern snout ela lowering about 600 m in addition several frontal moraine complexes could be identified at the valley bottom of the koksu river between 3100 m asl and the modern glacier snout at 3650 m asl the complexes can be assigned to the following glacier advances late glacial ela lowering 200 300 m early holocene to end of late glacial younger dryas ela lowering about 110 m neoglacial ela lowering about 50 m and little ice age ela lowering about 50 m similar glacier advances could be reconstructed according to the soil development on the lateral moraines near the abramov glacier at 3600 4000 m asl determination of pedogenic iron oxides corroborated the morphologic and radiocarbon results

climatic and atmospheric circulation pattern variability from ice core isotope geochemistry records altai tien shan and tibet several firn ice cores were recovered from the siberian altai belukha plateau central tien shan inilchek glacier and the tibetan plateau zuoqiupu glacier bomi from 1998 to 2003 the comparison analyses of stable isotope geochemistry records obtained from these firn ice cores identified the physical links controlling the climate related signals at the seasonal scale variability the core data related to physical stratigraphy meteorology and synoptic atmospheric dynamics were the basis for calibration validation and clustering of the relationships between the firn ice core isotope geochemistry and snow accumulation air temperature and precipitation origin the mean annual accumulation in water equivalent was 106 g cm 2 a 1 at inilchek glacier 69 g cm 2 a 1 at belukha and 196 gc m 2 a 1 at zuoqiupu the slopes in regression lines between the d 18 o ice core records and air temperature were found to be positive for the tien shan and altai glaciers and negative for southeastern tibet where heavy amounts of isotopically depleted precipitation occur during summer monsoons the technique of coupling synoptic climatology and meteorological data with d 18 o and d excess in firn core records was developed to determine climate related signals and to identify the origin of moisture in altai two thirds of accumulation from 1984 to 2001 was formed from oceanic precipitation and the rest of the precipitation was recycled over aral caspian sources in the tien shan 87 of snow accumulation forms by precipitation originating from the aral caspian closed basin the eastern mediterranean and black seas and 13 from the north atlantic

timing and extent of quaternary glaciations in the tianger range eastern tian shan china investigated using 10be surface exposure dating abstract reconstructing glacial chronologies with consistent methods is critical for efforts to examine the timing and pattern of past climate change cosmogenic 10be surface exposure dating has been widely used to constrain the timing of glacial events on the tibetan plateau and in central asia however few such studies have been conducted in the chinese tian shan and available 10be ages from this region have only provided evidence for glacial events during the global last glacial maximum glgm and lateglacial here we present 45 10be surface exposure ages from glacial landforms in the ala and daxi valleys two formerly glaciated valleys draining the tianger range eastern tian shan combined with previously published 10be surface exposure ages from the daxi valley in the source area of the urumqi river the new ages record five major glacial events during marine oxygen isotope stages mis 6 or older 4 3 2 and 1 during the little ice age lia landforms from glacial events since mis 2 are found on the northern slope of the tianger range daxi valley whereas evidence for the older glacial events is only preserved on its southern slope ala valley this disparity may be caused by different preservation and micro climatic conditions on the northern and southern slopes of this mountain range due to differences in gradient and aspect the lia glacial advances are apparently the only holocene glacial event recorded in this area earlier holocene glacial events were probably so restricted in extent that they were destroyed by subsequent lia advances

temperature sensitive tien shan tree ring chronologies show multi centennial growth trends two millennia length juniper ring width chronologies processed to preserve multi centennial growth trends are presented for the alai range of the western tien shan in kirghizia the chronologies average the information from seven near timberline sampling sites and likely reflect summer temperature variation for comparison chronologies are also built using standard dendrochronological techniques we briefly discuss some qualities of these inter decadal records and show the low frequency components removed by the standardization process include a long term negative trend in the first half of the last millennium and a long term positive trend since about ad 1800 the multi centennial scale alai range chronologies where these trends are retained are both systematically biased but in an opposite sense in their low frequency domains nevertheless they represent the best constraints and estimates of long term summer temperature variation and reflect the medieval warm period the little ice age and a period of warming since about the middle of the nineteenth century

holocene east asian monsoonal precipitation pattern revealed by grain size distribution of core sediments of daihai lake in inner mongolia of north central china abstract two sediment cores recovered in the central part of daihai lake in north central china were analysed at 2 to 4 cm intervals for grain size distribution grain size distributions of the lake sediments are inferred to be a proxy for past changes in east asian monsoon precipitation such that greater silt size percentage and higher median grain size reflect increased monsoonal precipitation rates the grain size record of daihai lake sediments spanning the last ca 10 000 yr indicates that the monsoonal precipitation in the lake region can be divided into three stages the early middle and late holocene during the early holocene before ca 7900 cal yr bp the median grain size md and the silt fraction content were relatively low and constant suggesting relatively low precipitation over the lake region the middle holocene between ca 7900 and 3100 cal yr bp was marked by intensified and highly variable monsoonal precipitation as indicated by high and variable md values and silt contents of the lake sediments during this period average precipitation rate gradually increased from ca 7900 to 6900 cal yr bp displayed intense oscillations between ca 6900 and 4400 cal yr bp and exhibited a decreasing trend while fluctuating from ca 4400 to 3100 cal yr bp although generally high during the middle holocene both the md and the silt content assumed distinctly low values at the short intervals of ca 6500 6400 6000 5900 5700 5600 4400 4200 cal yr bp implying that monsoonal precipitation might have been significantly reduced during these intervals during the late holocene since ca 3100 cal yr bp grain size values suggest that precipitation decreased however during the late holocene relatively higher md values and silt contents occurring between ca 1700 to 1000 cal yr bp may denote an intensification of hydrological cycles in the lake area changes in the east asian monsoonal precipitation were not only directly linked with the changing seasonality of solar insolation resulting from progressive changes in the earth s orbital parameters but also may have been closely related to variations in the temperature and size of the western pacific warm pool in the intensity of the el nino southern oscillation and in the path and strength of the north equatorial current in the western pacific

time marker of 137cs fallout maximum in lake sediments of northwest china abstract caesium 137 137cs has no natural source and is commonly employed in establishing the chronology of recent lake sediments in the anthropocene epoch because of their location in the northern mid latitude westerlies circulation region downwind of the chernobyl accident and their proximity to the lop nur chinese nuclear testing cnt site lake sediments in nw china record a137cs fallout maximum of global atmospheric thermonuclear weapon tests gtwt in 1963 1964 common era ce with probably local fallout subpeaks due to the chernobyl accident in 1986 ce and cnt in 1976 ce this complexity means that the use of 137cs fallout maximum in lake sediments as a time marker in nw china is thus far not well constrained impeding assessment of recent and future changes in paleoclimate and human activities to identify the 137cs time marker and provide a reliable chronology of surface lake sediments for investigating paleoclimatic changes and for defining the anthropocene epoch in nw china during the last 50 100 years here we describe chronologies of 6 near surface sediment cores from nw china based on 137cs and 210pb activities and review the chronology of 23 lake sediments and 10 ice cores from nw china and central asia based on 137cs 210pb 239 240pu 3h 241am and beta activity dating methods and annual layer counting as well as 240pu 239pu isotopic ratios based on the potential influence of radioactivity transport from the chernobyl accident and cnt and the comparison with deposition records of 26 european lake sediments and 5 alpine ice cores we propose that the 137cs fallout maximum of lake sediments in nw china and central asia is primarily attributable to gtwt and that there is no unambiguous evidence to confirm the chernobyl and cnt derived 137cs local fallout subpeaks taking into account the approximately one year delay between injection of 137cs into the atmosphere and its incorporation in lake sediment records we conclude that the 137cs fallout maximum in lake sediments of nw china provides a reliable gtwt time marker for 1964 ce

general characteristics of temperature variation in china during the last two millennia three alternate china wide temperature composites covering the last 2000 years were established by combining multiple paleoclimate proxy records obtained from ice cores tree rings lake sediments and historical documents five periods of temperature variation can be identified a warm stage in ad 0 240 a cold interval between ad 240 and 800 a return to warm conditions from ad 800 1400 including the medieval warm period between ad 800 1100 the cool little ice age period between 1400 1920 and the present warm stage since 1920 regional temperature variation is found during ad 800 1100 when warm conditions occurred in eastern china and in the northeastern tibetan plateau and in ad 1150 1380 when the southern tibetan plateau experienced a warm interval in contrast evidence for cool conditions during the lia is more consistent among the proxy records the temperature reconstructions for china and the northern hemisphere show good agreement over the past millennium

mid to late holocene paleoenvironmental changes and glacier fluctuations reconstructed from the sediments of proglacial lake buruo co northern tibetan plateau abstract glaciers on the tibetan plateau are an important freshwater resource for large populations in south and southeast asia therefore it is important to understand past variations in glacier activity in the region to assess their possible response to ongoing climatic warming here we present the results of analyses of grain size total organic carbon pollen ratio artemisia to chenopodiaceae and the element content of a 435 cm long sediment core from proglacial lake buruo co on the northern tibetan plateau our results indicate that the buruo co catchment experienced relatively warm and humid conditions during 5 2 4 0 cal kyr bp during which retreating glaciers released large amounts of freshwater precipitation was also abundant during this interval as a result of the relatively strong indian summer monsoon and weaker westerlies and thus the lake level was high during 4 0 1 3 cal kyr bp the westerlies were gradually enhanced and the climate became colder and drier in response the glaciers advanced and the lake level decreased during 1 3 0 cal kyr bp under relatively cold conditions a large volume of glacial ice was maintained nevertheless under the westerlies influence the lake level rose four episodes of glacial advance are detected at 3 6 3 4 3 2 2 3 1 9 1 7 and 0 4 0 1 cal kyr bp these episodes correspond well with bond events in the north atlantic implying that climate change and glacial activity at buruo co were largely driven by variations in northern hemisphere insolation and by climatic oscillations in the north atlantic region via the influence of the westerlies

continental scale temperature variability during the past two millennia past global climate changes had strong regional expression to elucidate their spatio temporal pattern we reconstructed past temperatures for seven continental scale regions during the past one to two millennia the most coherent feature in nearly all of the regional temperature reconstructions is a long term cooling trend which ended late in the nineteenth century at multi decadal to centennial scales temperature variability shows distinctly different regional patterns with more similarity within each hemisphere than between them there were no globally synchronous multi decadal warm or cold intervals that define a worldwide medieval warm period or little ice age but all reconstructions show generally cold conditions between ad 1580 and 1880 punctuated in some regions by warm decades during the eighteenth century the transition to these colder conditions occurred earlier in the arctic europe and asia than in north america or the southern hemisphere regions recent warming reversed the long term cooling during the period ad 1971 2000 the area weighted average reconstructed temperature was higher than any other time in nearly 1 400 years

continuous record of microparticle concentration and size distribution in the central greenland ngrip ice core during the last glacial period 1 a novel laser microparticle detector used in conjunction with continuous sample melting has provided a more than 1500 m long record of particle concentration and size distribution of the ngrip ice core covering continuously the period approximately from 9 5 100 kyr before present measurements were at 1 65 m depth resolution corresponding to approximately 35 200 yr particle concentration increased by a factor of 100 in the last glacial maximum lgm compared to the preboreal and sharp variations of concentration occurred synchronously with rapid changes in the 18o temperature proxy the lognormal mode of the volume distribution shows clear systematic variations with smaller modes during warmer climates and coarser modes during colder periods we find 1 7 m diameter during lgm and 1 3 m during the preboreal on timescales below several 100 years and the particle concentration exhibit a certain degree of independence present especially during warm periods when generally is more variable using highly simplifying considerations for atmospheric transport and deposition of particles we infer that 1 the observed changes of in the ice largely reflect changes in the size of airborne particles above the ice sheet and 2 changes of are indicative of changes in long range atmospheric transport time from the observed size changes we estimate shorter transit times by roughly 25 during lgm compared to the preboreal the associated particle concentration increase from more efficient long range transport is estimated to less than one order of magnitude

quaternary glaciation of muztag ata and kongur shan evidence for glacier response to rapid climate changes throughout the late glacial and holocene in westernmost tibet the glacial geology of two massifs muztag ata and kongur shan in western tibet was examined to help define the timing and style of glaciation in the semiarid regions of western tibet remote sensing geomorphic mapping and 10be terrestrial cosmogenic nuclide tcn surface exposure dating of boulders on the moraines and sediment in depth profiles show that glaciers advanced at least 12 times during at least the last two glacial cycles over this time the style of glaciation changed progressively from one that produced ice caps to one that produced less extensive and more deeply entrenched valley glaciers the timing of the two earliest glaciations is poorly defined but they likely occurred prior to the penultimate glacial cycle the karasu glacial stage and the early part of the last glacial cycle or during the penultimate glacial cycle the subaxh glacial stage in contrast the timing of later glacial advances the olimde glacial stage is relatively well defined showing quasiperiodical oscillations on millennial time scales 17 1 0 3 ka 13 7 0 5 ka 11 2 0 1 ka 10 2 0 3 ka 8 4 0 4 ka 6 7 0 2 ka 4 2 0 3 ka 3 3 0 6 ka 1 4 0 1 ka and a few hundred years before the present these data suggest that since the global last glacial maximum lgm the glaciers in western tibet likely responded to northern hemisphere climate oscillations rapid climate changes with minor influences from the south asian monsoon this study provides the first well defined glacial geologic evidence to suggest that glaciers in western tibet respond to rapid climate changes on millennial time scales throughout the late glacial and holocene

late holocene indian summer monsoon precipitation history at lake lugu northwestern yunnan province southwestern china abstract knowledge of late holocene precipitation variability in the northwestern yunnan province is important for understanding the indian summer monsoon ism dynamics in this study we present a proxy record of the ism precipitation history at lake lugu covering the last 2 900 years based on grain size and carbon nitrogen c n ratio in the northwestern yunnan province the results show centennial variations in ism precipitation with two remarkably dry intervals from 750 to 1167 ad and from 1733 ad to the present and two relatively wet intervals from 898 bc to 750 ad and from 1167 to 1733 ad a comparison between the record at lake lugu and the pollen record at lake erhai both in the northwestern yunnan province suggests that dry climate conditions prevailed during the medieval warm period mwp and over the last 100 200 years whereas relatively humid conditions prevailed during the little ice age lia these characteristics are generally similar to those of the climate patterns in extensive areas dominated by the ism e g southwestern southern china southeastern southern tibetan plateau northeastern india himalayas southern oman and equatorial eastern africa but anti phased with the climate patterns in the wide areas dominated by the east asian summer monsoon easm e g northern northeastern china and north central japan we speculate that both the variations in the sea surface temperature sst over the tropical indo pacific ocean the ocean atmosphere coupling processes and the migration of the mean position of the intertropical convergence zone itcz should be responsible for the hydroclimatic contrasts over the asian summer monsoon asm region on centennial timescales during the last 2 000 years

210pb sediment radiochronology an integrated formulation and classification of dating models abstract environmental archives such as sediments banded corals and tree rings are widely used to reconstruct past environmental conditions of ecosystems in particular 210 pb has been used during more than 4 decades through dating of undisturbed sediment cores to study ecosystem changes during the last 100 yr since its inception diverse dating models have been proposed developed used and validated in numerous environments but their nomenclature and formulation is not homogenous in this work we emphasize that conceptual models used to date undisturbed sediment cores can be deduced from a single fundamental equation which relates excess 210 pb concentration in sediment its flux to the sediment surface and mass accumulation rate from this equation models were consistently named based on the main hypothesis used and using a unified and logical nomenclature dating equations were derived in detail we applied in detail most of the described models to a sediment core from mexico and uncertainty expressions were also included finally some recommendations to use the models are proposed we believe that this work can facilitate the use of 210 pb as a tool to date sediment cores in a more homogeneous way

geomorphology of anomalously high glaciated mountains at the northwestern end of tibet muztag ata and kongur shan article i nfo muztag ata and kongur shan massifs represent a significant area of anomalously high topography at the northwestern end of the tibetan plateau rising to n7500 m above sea level asl from the plateau that has an average elevation of 3500 m asl these massifs provide an excellent opportunity to test geomorphic concepts such as the glacial buzz saw model using remote sensing digital elevation modeling field mapping and terrestrial cosmogenic nuclide tcn methods the massifs were examined to determine the relative importance of tectonics and geomorphic processes in shaping the regional landscape and to provide a framework for testing geomorphic models the gneiss domes that underlie the peaks are the result of exhumation along the kongur detachment fault that has unroofed the massifs at a rate of between 4 6 km ma over the last few million years this has resulted in rapid uplift and active seismicity which is exemplified by the numerous fresh fault scarps throughout the region and large historic earthquakes the geomorphic system is dominated by glaciation and the region contains extensive successions of moraines and paraglacial landforms including fans terraces and landslides glaciers have oscillated considerably throughout the latter part of the quaternary and three major glacier stages are recognized karasu oldest olimde and subaxh youngest glacial stage that include at least 10 smaller glacial advance the style of glaciation has changed over time from expanded ice caps to piedmont glaciers to valley and cirque glaciers this possibly reflects a change in climate and or topographic constraints as the massifs grew and became incised the topography and glaciers in the region vary across the massifs divided by a broadly n s trending high ridge and watershed the western portion situated upwind the stoss slopes of the mid latitude westerlies that bring moisture to the region has gentle high topography and small valley glaciers in contrast on the eastern leeward slopes gradients are higher and long debris covered valley glaciers are present the hypsometry of the region indicate two peaks in the distribution frequency of elevation 3600 4100 m and 4400 4800 m asl these two elevation zones are consistent in space with the former equilibrium line altitudes during the olimde and subaxh glacial stages and suggest that glacial erosion most effective at the ela has helped control topography this observation supports the glacial buzz saw hypothesis which argues that glaciers determine hypsometry by means of rapid surface erosion based on tcn methods basin wide rates of erosion range from 0 1 to 1 4 km ma and are five to ten times lower than the unroofing rate of both massifs the discrepancy over different time scales suggests that initial unroofing was produced by abrupt tectonic uplift and that the unroofing of the massifs has continued at a slower pace during the late quaternary

late holocene coupled moisture and temperature changes on the northern tibetan plateau the northern tibetan plateau involves complex interactions between the mid latitude westerly circulation and the subtropical asia monsoon circulation acting as a bridge communicating high and low latitude climatic processes previous studies from the region suggest relatively wet conditions in cold periods during the late holocene for instance the little ice age lia however the inference of such temperature moisture association is subject to the large uncertainty in lacustrine 14c chronology due to the particularly large lake reservoir effect in the region here we take a different approach by reconstructing paired temperature and moisture records from the same sediment cores to assess the temperature moisture association independent of chronology uncertainty we use alkenone indices uk 37 and c37 4 to reconstruct high resolution temperature and moisture changes simultaneously from two lakes in the qaidam basin northern tibetan plateau over the last 2500 years characterized by marked climatic variability our paired records confirm the warm dry and cold wet association in arid northwestern china during the late holocene opposite to the warm wet and cold dry association in subtropical asian monsoonal regions our moisture records further suggest substantially drier conditions during the medieval warm period mwp than the current warm period lastly the temperature and moisture changes inferred from our records can be well correlated with solar irradiance changes suggesting a possible link between solar forcing and natural climate variability during the late holocene on the northern tibetan plateau

bioclimatic change of the past 2500 years within the balkhash basin eastern kazakhstan central asia abstract on the bases of analytical data of an 850 cm long sediment core collected from balkhash lake with a chronological control of seventeen ams dates this research reconstructed the lake salinity using carbonate content and the oxygen isotopic composition as proxies and reconstructed the basin wide moisture using a c ratio and pollen concentration as proxies basin wide mean annual temperature mat and mean annual precipitation map were reconstructed using climate pollen response surface method the reconstruction appears to be supportive to the early proposition that the climate in the westerlies dominated areas has been generally characterized by cool wet and warm dry modes balkhash basin has experienced three stages of climate change during the past 2500 years cool wet from 2500 to 1800 cal bp moderate from 1800 to 650 cal bp and cooling and wetting during the past 650 years with the past 100 showing warming and drying the moisture evolution has closely followed the map variation and the mat must have modulated the moisture evolution through controlling the evaporation the first order variation in lake salinity has been controlled by basin wide temperature i e low temperature raises the salinity level in the lake through reducing the ice melt water supply to the lake the second order variation in the lake salinity seems to be modulated by pronounced variations in basin wide moisture those low amplitude variations in basin wide moisture levels left no detectable imprints in lake salinity proxy records

a high resolution diatom inferred palaeoconductivity and lake level record of the aral sea for the last 1600 yr formerly the world s fourth largest lake by area the aral sea is presently undergoing extreme desiccation due to large scale irrigation strategies implemented in the soviet era as part of the intas funded climan project into holocene climatic variability and the evolution of human settlement in the aral sea basin fossil diatom assemblages contained within a sediment core obtained from the aral sea have been applied to a diatom based inference model of conductivity r2 0 767 rmsep 0 469 log10 s cm 1 this has provided a high resolution record of conductivity and lake level change over the last ca 1600 yr three severe episodes of lake level regression are indicated at ca ad 400 ad 1195 1355 and ca ad 1780 to the present day the first two regressions may be linked to the natural diversion of the amu darya away from the aral sea and the failure of cyclones formed in the mediterranean to penetrate more continental regions human activity however and in particular the destruction of irrigation facilities are synchronous with these early regressions and contributed to the severity of the observed low stands

late quaternary glaciation in the kyrgyz tien shan the tien shan of kyrgyzstan contains multiple moraines and drift from late quaternary glaciations the spatial temporal distribution of the glaciers inferred from the moraines suggests that the main factor controlling glacier advance here was the availability of moisture the dominant modern climatic signatures in northern central asia include orographic thunderstorms in summer cold and dry siberian high pressure cells in winter and westerly cyclonic storms from the north atlantic and eastern mediterranean in spring and fall changes in any of these systems during the late quaternary would have varied precipitation delivery to and glacier growth in the kyrgyz tien shan geomorphic mapping and reconnaissance level 10be cosmic ray exposure dating of moraine sequences in six drainages indicate that there were multiple maximum advances of similar extents and equilibrium line depressions across the range glaciers in the north and east of the kyrgyz tien shan last advanced to their maximum positions during marine oxygen isotope stage mis 5 and again during mis 4 while in the south and west of the range advance occurred during mis 3 in contrast to maritime europe and north america there is no evidence of a major glacial advance during mis 2 glacier advances during mis 2 and since were restricted to the vicinity of modern glaciers allowing the older glacial record to be preserved well