a record of holocene climate change in the guanzhong basin china based on optical dating of a loess palaeosol sequence optical dating was used to obtain a chronology for a loess palaeosol sequence in the guanzhong basin on the loess plateau in china the sedimentary sequence recorded two dry episodes 3 7 2 4 ka and 1 2 0 8 ka ago in the holocene as shown by the presence of two layers of loess within the holocene deposits these two arid events are consistent with records of global climate change in the holocene and also coincident with major historic events in china this finding suggests that loess paleosol sequences in china can record global climate changes and implies that rapid climate change affected the progress of human civilization in addition changes in the sedimentation rate through the section suggest that agricultural expansion may have accelerated the rate of dust accumulation

holocene climate changes in the monsoon arid transition reflected by carbon concentration in daihai lake of inner mongolia two sediment cores recovered in the central part of daihai lake in north central china were analysed at 2 to 4 cm intervals for total inorganic and organic carbon tic and toc concentrations the tic concentration is inferred to reflect temperatures over the lake region and an increase in the tic concentration implies an increase in the temperature toc concentration is considered to reflect the precipitation in the lake basin and higher toc concentrations denote more precipitations thus ams 14c time series of the tic and toc records of daihai lake sediments uncovers a detailed history of changes in temperature and precipitation in north central china during the last c 12 000 yr the holocene an epoch of postglacial warmth started c 11 500 cal yr bp and can be subdivided into three stages the early c 11 500 8100 cal yr bp middle c 8100 3300 cal yr bp and the late holocene c 3300 0 cal yr bp the climate was warm and dry during the early holocene warm and wet during the middle holoce

youngest volcanism about 1 million years ago at kahoolawe island hawaii abstract young volcanic deposits in kahoolawe island cutting up through the caldera filling lava colluvium and talus in the west wall of kanapou bay had long been stratigraphically considered the rejuvenated stage products new k ar ages combined with magnetic polarity data show that young volcanism was at about 0 98 1 04 ma and indicate no substantial quiescence between the filling of the caldera and the young volcanism this result and the tholeiitic characteristics of the young deposits suggest they are a component of late shield stage volcanism

asian summer monsoonal variations during the holocene revealed by huguangyan maar lake sediment record abstract high resolution records of summer monsoonal evolution in the holocene are essential to paleoclimate reconstruction but are hard to obtain here we provide a continuous well dated high resolution record from huguangyan maar lake located in the west pacific climate regime multi proxies including chlorophyll a toc sr rb ratio and magnetic susceptibility have been used to reconstruct the monsoon variations in the holocene higher chlorophyll a values are related with stronger summer monsoon and vice versa high temporal resolution radiocarbon dating enables us to divide summer monsoon evolution stages summer monsoon in zhanjiang area was strongest in the early holocene but began to decline at 6080 yr bp and weakened substantially since about 3600 yr bp the transition around 6080 yr bp supported by our high resolution dating lags the previous estimates by 1700 years the decreasing summer solar radiation at 30 n through the holocene is probably responsible for gradually weakened summer monsoon the anti phased co variation of summer monsoon intensity and enso activity throughout the holocene suggests that they could be interlinked driven together by solar radiation at orbital scale

paleohydrological changes in southeastern china from 13 1 to 2 5 ka based on a multi proxy peat record abstract investigating the hydrological changes in the east asian monsoon regions of china during the holocene could provide important insights into the mechanism and future variability of the east asian summer monsoon easm rainfall however existing studies have revealed large inconsistencies in the spatiotemporal pattern of the hydrological changes in east china probably due to different climatic sensitivities of various proxies the uncertainties of sedimentary chronologies and unevenness of proxy record distributions thus multi proxy records with precise dating are needed especially in southeastern china which is one of the key places to determine the spatiotemporal pattern with few hydrological records available in this study hopanoid flux humification degree the concentration of total organic carbon toc and the atomic ratio between total organic carbon and total nitrogen c n of organic matter were applied on shuizhuyang szy peat cores retrieved from southeastern china to reconstruct the paleohydrological changes spanning from 13 1 to 2 5 ka results of these proxies reveal a moderately dry period during 13 1 11 6 ka followed by an interval of increasing aridity from 11 6 to 8 6 ka the holocene optimum referred here as an effective moisture maximum occurred at 8 6 4 4 ka before the climate became drier from 4 4 to 2 5 ka the hydrological changes in szy during the holocene with a mid holocene holocene optimum are consistent with the regional climate records in southeastern china such an overall arid wet arid pattern in southeast china during the holocene closely tracked the variations in the west to east sea surface temperature sst gradient in tropical pacific we preliminarily concluded the enso state and the western pacific subtropical high wpsh position associated with variations in the thermal state of the tropical pacific were primarily responsible for the hydrological changes in southeast china during the holocene our study added new evidence to the spatiotemporal pattern of hydrological changes in eastern china during the holocene

holocene climate change in henan area a synthesis of proxy records abstract henan area is climatologically situated in the transition between northern and southern china and the transition is reported to be highly sensitive to climate changes during the holocene to better understand the holocene climatic and environmental changes in henan area where high quality data are lacking this paper first reviewed those published palaeoenvironmental records in attempt to provide a low resolution framework of the holocene environmental changes in henan area and then synthesized the moisture proxy records from the surrounding areas in attempt to define a high resolution trend of the holocene moisture variation for our target site i e zhengzhou within henan area two major conclusions can be drawn first the high resolution holocene moisture curve for our target site well follows the general moisture trend of china and the curve is well corroborated by two recently reported data sets one from mangshan loess palaeosol sequence and another from laomu dongshiya cave second our synthesis supports an earlier notion stating that the holocene moisture optimum in china was a delayed response to the oceanic holocene thermal optimum the latter might in turn be a delayed response to the summer insolation peak

moisture variations in lacustrine eolian sequence from the hunshandake sandy land associated with the east asian summer monsoon changes since the late pleistocene abstract paleoclimate records currently lack sufficient geographic detail to understand the spatiotemporal evolution of east asian summer monsoon easm rain belt since the late pleistocene in particular there is no consensus on whether the easm rain belt reached its modern northern limit by the early holocene here we present inferred moisture variations from a multi parameter absolute dated lacustrine eolian sequence from northern china that date back to the late pleistocene 14 ka bp or thousand years ago we observed a sharp transition towards wet conditions at the onset of the holocene epoch maximum wet climate occurred here during 11 3 8 5 ka the climate remained predominantly wet until 4 2 ka then it became progressively drier we observed alternating organic rich fine grained lake deposits and organic depleted coarse grained eolian sand layers during 14 7 ka these layers correspond to sedimentation associated with the allerod younger dryas yd post yd warming pre boreal oscillation pbo early holocene and 8 2 ka event we interpreted the orbital scale moisture variation at our study site to the changes in insolation assigning these abrupt and short lived changes during the late pleistocene holocene transition to a persistent teleconnection between the north atlantic and east asian climate zones

adiabatic westward drift of indian monsoon depressions a large fraction of the rain received by continental india is produced by cyclonic vortices with outer radii of about 1000 km that are contained within the larger scale south asian monsoon flow the more intense occurrences of these vortices are called monsoon depressions these consist of bottom heavy columns of relative vorticity that propagate to the northwest in time mean low level eastward flow previous studies have argued that this apparent upstream propagation is caused by dynamical lifting west of the vortex centre with the resulting ascent producing vortex stretching that shifts the vortex to the west here analysis of over 100 indian monsoon depressions is used to show that low level vortex stretching has a spatial structure inconsistent with the observed propagation and is balanced by other terms in the low level vorticity budget instead monsoon depressions are shown to consist of potential vorticity maxima that have peak amplitude in the middle troposphere and propagate westward by nonlinear horizontal adiabatic advection i e beta drift the precipitating ascent in monsoon depressions makes a more minor contribution to the total storm motion and primarily acts to maintain the upright structure of the vortex these results suggest a new view of indian monsoon depressions as potential vorticity columns that propagate primarily by adiabatic dynamics

what is the timing of orbital scale monsoon changes abstract a major but little noted divergence of opinion has developed among climate scientists over the orbital scale periodicity and phasing of tropical monsoon variations kutzbach 1981 monsoon climate of the early holocene climate experiment with earth s orbital parameters for 9000 years ago science 214 59 61 proposed that monsoons are driven by northern summer insolation at the precession period but clemens and prell 1990 late pleistocene variability of arabian sea summer monsoon winds and continental aridity eolian records from the lithogenic component of deep sea sediments paleoceanography 5 109 145 2003 a 350 000 year summer monsoon multi proxy stack from the owen ridge northern arabian sea marine geology 201 35 51 inferred a more complicated response tied to latent heat transfer from the southern hemisphere because tropical monsoons affect climate over a vast area resolving this divergence is an important task for the climate community the purpose of this note is to highlight definitive evidence from high resolution dating of speleothem calcite that provides unambiguous support for the kutzbach hypothesis

high resolution evidence from southern china of an early holocene optimum and a mid holocene dry event during the past 18 000 years abstract computer models suggest that the holocene optimum for east asian summer monsoon precipitation occurred at different times in different regions of china previous studies indicate that this time transgressive holocene optimum should have been experienced about 3000 yr ago in southern china in this study we describe a section which allows us to test this timing directly we have closely examined high resolution eutrophic peat mud sequences covering the past 18 000 cal yr at dahu jiangxi on the southern boundary of the mid subtropical zone in china late pleistocene successions in the dahu record indicate cooler and much wetter conditions relative to synchronous events in north central china our results indicate that the holocene optimum occurred between ca 10 000 and 6000 cal yr ago in southern china consistent with the global pattern conditions were relatively dry and cold from 6000 to 4000 cal yr ago our data also support the conclusion that the last deglaciation to early holocene in the south was much wetter resulting in the formation of dense broad leaved forests which could have acted to moderate land temperature 10 000 to 6000 cal yr ago yielding a stable early holocene climate after 6000 cal yr forest reduction led to unstable land temperatures and possibly to a northerly shift of the subtropical high pressure system whatever the mechanism these changes resulted in decreased precipitation between 6000 and 4000 cal yr b p in southern china

holocene moisture variations across china and driving mechanisms a synthesis of climatic records based on the review of 33 holocene moisture reconstructions that passed quality scrutiny temporal and spatial patterns of regional moisture variations are delineated the regionally averaged moisture index from xinjiang demonstrates that the moisture index has been persistently climbing since 10 ka cal bp and that the period between 4 and 0 ka cal bp is the holocene moisture optimum comparison of the moisture index of xinjiang region with the winter climate of northern europe leads us to propose that the holocene moisture variations in xinjiang region have been controlled by the winter temperature variations in the north atlantic region the regionally averaged moisture index from the tibetan plateau shows that the moisture has been persistently declining since 11 ka cal bp and that the period between 11 5 and 7 5 ka cal bp was the holocene moisture optimum the parallel trends between the moisture level in the tibetan plateau and the indian summer monsoon strength retrieved from the arabian sea suggest that the tibetan plateau has been under influence of the indian summer monsoon throughout the holocene the regionally averaged moisture index curves from northern china and southern china are the delayed reflections of the east asian summer monsoon strength to the solar radiation that is the peak insolation was responded by the holocene oceanic thermal optimum with significant time lags and the oceanic thermal optimum was then responded by the holocene moisture optimum in southern china and northern china also with some time lags the differences in the moisture index curve shapes and in the durations of the holocene moisture optimum between northern china and southern china suggest that the strength of the east asian summer monsoon had gradually transgressed northward in the early holocene and gradually regressed southward in the late holocene

impact of ice sheet induced north atlantic oscillation on east asian summer monsoon during an interglacial 500 000 years ago marine isotope stage mis 13 an interglacial about 500 000 years ago is unique due to an exceptionally strong east asia summer monsoon easm occurring in a relatively cool climate with low greenhouse gas concentrations ghg this paper attempts to find one of the possible mechanisms for this seeming paradox simulations with an earth system model loveclim show that the presence of ice sheets over north america and eurasia during mis 13 induces a positive phase of the winter north atlantic oscillation nao like feature the ocean having a longer memory than the atmosphere the oceanic anomalies associated with nao persists until summer the signals of summer nao are transmitted to east asia to reinforce the monsoon there through the stationary waves excited at the asian jet entrance the geopotential height shows clearly a mid latitude wave train with positive anomalies over the eastern mediterranean caspian sea and the okhotsk sea and a negative anomaly over lake baikal this reinforces the effect of the high latitude wave train induced independently by the eurasian ice sheet topography as shown in previous study these features reinforce the meiyu front and enhance the precipitation over east asia the results obtained from loveclim are further confirmed by an atmospheric general circulation model arpege

reconstruction of climate and vegetation changes of lake bayanchagan inner mongolia holocene variability of the east asian monsoon a high resolution pollen and pediastrum record spanning 12 500 yr is presented for lake bayanchagan 115 21 e 41 65 n and 1355 m a s l southern inner mongolia individual pollen taxa pt mat and the pft affinity scores pft mat were used for quantitative climatic reconstruction from pollen and algal data both techniques indicate that a cold and dry climate similar to that of today prevailed before 10 500 cal yr b p the wettest climate occurred between 10 500 and 6500 cal yr b p at which time annual precipitation was up to 30 60 higher than today the early holocene increases in temperature and precipitation occurred simultaneously but mid holocene cooling started at approximately 8000 cal yr b p 1500 yr earlier than the drying vegetation reconstruction was based on the objective assignment of pollen taxa to the plant functional type the results suggest that this region was dominated by steppe vegetation throughout the holocene except for the period 9200 to 6700 cal yr b p when forest patches were relatively common inner mongolia is situated at the limit of the present east asian monsoon and patterns of vegetation and climate changes in that region during the holocene probably reflect fluctuations in the monsoon s response to solar insolation variations the early to middle holocene monsoon undoubtedly extended to more northern latitudes than at present

variation of east asian monsoon precipitation during the past 21 k y and potential co2 forcing paleoclimatic research can provide critical insight on causes of change in the east asian monsoon which influences the lives of 1 6 billion people today in this study we use paleoclimatic indexes from chinese loess deposits which have clear climatic implications and are independently dated to reconstruct the monsoon precipitation since 21 ka our results show that monsoon precipitation persistently decreased from 21 ka to ca 8 ka and increased after ca 8 ka with a precipitation peak at 8 3 ka these changes in east asian summer monsoon precipitation are synchronous with changes in high northern latitude ice volume ice cover and atmospheric co2 these new data suggest that variation of the monsoon precipitation was probably driven by co2 forced high northern latitude temperature changes shifting the location of the intertropical convergence zone that dominates monsoon precipitation our trace 21000 modeling experiment supports this interpretation

holocene tephrostratigraphic framework and monsoon evolution of east asia key tephra beds for synchronising palaeoclimate records abstract in east asia our understanding of holocene climate change forcing mechanisms and propagation require the precise chronological control of palaeoclimate records to allow robust integration of data sets the existing chronologies predominantly based on 14c method however are not sufficient to constrain key questions about abrupt climate shifts that occur within a century in the transitions between states widely dispersed tephra layers allow precise dating and synchronisation of sedimentary archives providing a chronological framework for integrating records especially where the visible tephra record is complemented by the addition of cryptotephra non visible ash despite significant tephra studies in this region however a comprehensive holocene tephra framework is not available to address this issue we carry out a thorough review on holocene tephra investigations undertaken in japan using widespread tephra beds we present an integrated tephra framework and suggest the way forward for establishing this as a wider approach for east asia the framework is based on twenty two ash layers that are mainly from japan and to a lesser extent china n korea s korea and russia each tephra is assessed in terms of chronology geochemistry and distribution the framework is compared with high resolution palaeoclimate records from east asia using this we demonstrate regional variations in monsoon evolution and more importantly the potential of tephra isochrons in constraining such variations given the scarce identification of tephra layers in those well resolved palaeoclimate records we advocate a more systematic employment of the cryptotephra method which would potentially lead to a significant advance in east asian tephrochronology and the correlation of palaeoclimate archives in the region

a record of the southern oscillation index for the past 2 000 years from precipitation proxies the el nino southern oscillation enso is a coupled ocean atmosphere climate phenomenon in the tropical pacific ocean the interannual climate variations have been shown to modify both the hadley and walker meridional and zonal atmospheric circulations with strong impacts on global climate 1 3 proxy based reconstructions of the southern oscillation index on a multi decadal scale have shown that the strength and frequency of el nino occurrences have varied over the past millennium 4 7 here we compile reconstructions of precipitation 8 15 from regions that experience substantial enso variability to extend the multidecadal scale southern oscillation index to include the past 2 000 years we find that the medieval warm period similar to ad 800 1300 was characterized by a negative index which indicates more el nino dominated conditions whereas during the little ice age similar to ad 1400 1850 more la nina dominated conditions prevailed the southern oscillation index we derive is significantly correlated with reconstructions of solar irradiance and mean northern hemisphere temperature fluctuations

asynchronous holocene optimum of the east asian monsoon abstract the spatial and temporal distribution of summer monsoon precipitation or effective moisture during the holocene has been reconstructed on the basis of geological data including lake levels pollen profiles and loess paleosol records in addition the summer july precipitation increment effective precipitation and monsoon strength index have been obtained from numerical modeling experiments both geological data and numerical modeling indicate that the holocene optimum as defined by peak east asian summer monsoon precipitation was asynchronous in central and eastern china reaching a maximum at different times in different regions e g ca 10 000 8000 yr ago in northeastern china 10 000 7000 yr ago in north central and northern east central china ca 7000 5000 yr ago in the middle and lower reaches of the yangtze river and ca 3000 yr ago in southern china in southwestern china the maximum appeared ca 11 000 yr ago but probably was related to the maximum landward extension of the indian summer monsoon the regional shift in the maximum precipitation belt from northwest to southeast over the past 10 000 yr is interpreted as a response to changing seasonality related to orbital forcing of the climate the southeastward shift of the east asian summer monsoon maximum is consistent with the progressive weakening of the summer monsoon as the summer solar radiation anomaly decreased progressively through the holocene and the east asian monsoon index declined while the early maximum in southwestern china matches the maximum of the indian monsoon index

holocene east asian summer monsoon records in northern china and their inconsistency with chinese stalagmite δ18o records abstract monsoon precipitation over china exhibits large spatial differences it has been found that a significantly enhanced east asian summer monsoon easm is characterized by increased rainfall in northern china and by reduced rainfall in southern china and this relationship occurs on different time scales during the holocene this study presents results from a diverse range of proxy paleoclimatic records from northern china where precipitation variability is traditionally considered as an easm proxy our aim is to evaluate the evolution of the easm during the holocene and to compare it with all of the published stalagmite 18 o records from the asian monsoon region in order to explore the potential mechanism s controlling the chinese stalagmite 18 o we found that the intensity of the easm during the holocene recorded by the traditional easm proxy of moisture or precipitation records from northern china is significantly different from the chinese stalagmite 18 o records the easm maximum occurred during the mid holocene challenging the prevailing view of an early holocene easm maximum mainly inferred from stalagmite 18 o records in eastern china in addition all of the well dated holocene stalagmite 18 o records covering a broad geographical region exhibit a remarkably similar trend of variation and are statistically well correlated on different time scales thus indicating a common signal however in contrast with the clear consistency in the 18 o values in all of the cave records both instrumental and paleoclimatic records exhibit significant spatial variations in rainfall on decadal to centennial time scales over eastern china in addition both paleoclimatic records and modeling results suggest that holocene east asian summer monsoon precipitation reached a maximum at different periods in different regions of china thus the stalagmite 18 o records from the easm region should not be regarded as a reliable indicator of the strength of the east asian summer monsoon furthermore modern observations indicate that the moisture for precipitation in the east asian monsoon region is mainly derived from the indian ocean the moisture transport route from the indian ocean to the east asian monsoon region during the holocene is almost identical to that of modern precipitation therefore the strong correlation of 18 o records in the easm and indian summer monsoon ism regions and the similarity of the pattern of latitudinal changes in 18 o values in stalagmites and in modern meteoric precipitation along the water vapor transport route further suggests that the stalagmite 18 o records from the easm region are essentially a signal of the isotopic composition of precipitation which is determined mainly by changes in the 18 o of atmospheric vapor in the upstream source region over the indian ocean and indian monsoon region via the upstream depletion mechanism finally the main trends of the stalagmite 18 o records are strongly correlated with the known evolution of the ism and therefore these records reflect the history of the ism rather than that of the easm our findings support the conclusion that easm variability is mainly controlled by northern hemisphere summer insolation and was strongly modulated by ice volume during the last deglaciation and early holocene which delayed the response of the easm maximum to peak insolation forcing

holocene vegetation and climate dynamics of ne china based on the pollen record from sihailongwan maar lake abstract high resolution palynological analysis on annually laminated sediments of sihailongwan maar lake shl provides new insights into the holocene vegetation and climate dynamics of ne china the robust chronology of the presented record is based on varve counting and ams radiocarbon dates from terrestrial plant macro remains in addition to the qualitative interpretation of the pollen data we provide quantitative reconstructions of vegetation and climate based on the method of biomization and weighted averaging partial least squares regression wa pls technique respectively power spectra were computed to investigate the frequency domain distribution of proxy signals and potential natural periodicities pollen assemblages pollen derived biome scores and climate variables as well as the cyclicity pattern indicate that ne china experienced significant changes in temperature and moisture conditions during the holocene within the earliest phase of the holocene a large scale reorganization of vegetation occurred reflecting the reconstructed shift towards higher temperatures and precipitation values and the initial holocene strengthening and northward expansion of the east asian summer monsoon easm afterwards summer temperatures remain at a high level whereas the reconstructed precipitation shows an increasing trend until approximately 4000 cal yr bp since 3500 cal yr bp temperature and precipitation values decline indicating moderate cooling and weakening of the easm a distinct periodicity of 550 600 years and evidence of a mid holocene transition from a temperature triggered to a predominantly moisture triggered climate regime are derived from the power spectra analysis the results obtained from shl are largely consistent with other palaeoenvironmental records from ne china substantiating the regional nature of the reconstructed vegetation and climate patterns however the reconstructed climate changes contrast with the moisture evolution recorded in s china and the mid latitude semi arid regions of n china whereas a clear insolation related trend of monsoon intensity over the holocene is lacking from the shl record variations in the coupled atmosphere pacific ocean system can largely explain the reconstructed changes in ne china

monsoon climate of the early holocene climate experiment with the earth s orbital parameters for 9000 years ago values for the precession and obliquity of the earth 9000 years ago indicate that the global average solar radiation for july 9000 years ago was 7 percent greater than at present when the estimated solar radiation values are used in a low resulation climate model the model simulates an intensified continent scale monsoon circulation this result agrees with paleoclimatic evidence from africa arabia and india that monsoon rains were stronger between 10 000 and 5000 years ago than they are today

global characterization of the holocene thermal maximum we analyze the global variations in the timing and magnitude of the holocene thermal maximum htm and their dependence on various forcings in transient simulations covering the last 9000 years 9 ka performed with a global atmosphere ocean vegetation model in these experiments we consider the influence of variations in orbital parameters and atmospheric greenhouse gases and the early holocene deglaciation of the laurentide ice sheet lis considering the lis deglaciation we quantify separately the impacts of the background melt water fluxes and the changes in topography and surface albedo in the analysis we focus on the intensity of the maximum temperature deviation relative to the preindustrial level its timing in the holocene and the seasonal expression in the model the warmest htm conditions are found at high latitudes in both hemispheres reaching 5 c above the preindustrial level while the smallest htm signal is seen over tropical oceans less than 0 5 c this latitudinal contrast is mostly related to the nature of the orbitally forced insolation forcing which is also largest at high latitudes and further enhanced by the polar amplification the holocene timing of the htm is earliest before 8 ka bp in regions not affected by the remnant lis particularly nw north america e asia n africa n south america the middle east ne siberia and australia compared to the early holocene insolation maximum the htm was delayed by 2 3 ka over ne north america and regions directly downwind from the lis a similar delay is simulated over the southern ocean while an intermediate lag of about 1 ka is found over most other continents and oceans the seasonal timing of the htm over continents generally occurs in the same month as the maximum insolation anomaly whereas over oceans the htm is delayed by 2 3 months exceptions are the oceans covered by sea ice and north africa were additional feedbacks results in a different seasonal timing the simulated timing and magnitude of the htm are generally consistent with global proxy evidence with some notable exceptions in the mediterranean region sw north america and eastern eurasia 2012 elsevier ltd

time transgressive onset of the holocene optimum in the east asian monsoon region abstract the east asian summer monsoon affects precipitation and hence vegetation in the densely populated northwest pacific region yet a long standing controversy exists concerning the spatial and temporal dynamics of the holocene optimum ho in the east asian monsoon region here we use a detailed 14 000 year record reconstructing vegetation variations from a strategically selected crater lake from northeast china as well as a compilation of previous paleoclimatic studies to show that the ho began around 6 000 cal a bp in northeast china significantly later than generally recognized by comparing our paleoenvironmental data with holocene vegetation records from other regions of east asia we identified a marked northward shift for the onset of the ho from 10 260 cal a bp in south china to 6 000 cal a bp in northeast china the gradual northward transgression of the vegetation change could be caused by both the temperature and precipitation changes in different regions finally we fitted a regression model of the start of the ho period versus latitude which allowed us to make predictions for the beginning of the ho at different geographical locations this study reveals a strong relationship between latitude and the initiation of the ho and provides a window towards better understanding the forcing of vegetation changes in the east asian monsoon region

tephra evidence for the most recent eruption of laoheishan volcano wudalianchi volcanic field northeast china abstract wudalianchi volcanic field wdlc is one of the youngest intracontinental monogenetic volcanic fields in china the 1719 1721 ce laoheishan huoshaoshan eruption and the 1776 ce laoheishan eruption are the latest eruptions in wdlc based on the local historical records however most of the recent explosive eruptive products around wdlc are attributed to the 1719 1721 ce laoheishan huoshaoshan eruption while less attentions were paid on the 1776 ce laoheishan eruption there are two types of scoria fall deposits around laoheishan volcano i e the upper light grey high vesicular scoria deposit us and below dark low vesicular scoria deposit bs most of the glass shards from us exhibit 4 na2o while bs show 5 content with trachyandesitic to tephriphonolitic in composition that can be clearly distinguished from those from other nearby volcanic regions such as nuomin 150 km to nangelaqiushan lake nglq arxan chaihe 450 km to nglq longgang 700 km to nglq and jingbohu 550 km to nglq a cryptotephra layer is clearly revealed as a distinct peak in magnetic susceptibility measurements from nglq 8 km northwest to laoheishan volcano glass composition of the cryptotephra layer recorded in nglq is similar to the proximal us around laoheishan volcano on basis of historical records and field observations we ascribed us to the 1776 ce laoheishan eruption and bs to the 1719 1721 ce laoheishan huoshaoshan eruption consequently historical records assigned a precise age 1776 ce for the tephra recorded in nglq and thus can be used to refine the age model of these lacustrine sediments

millennial scale asian summer monsoon variations in south china since the last deglaciation abstract characterizing spatiotemporal variability of the asian summer monsoon asm is critical for full understanding of its behavior dynamics and future impacts the present knowledge about asm variations since the last glaciation in south china largely relies on several precisely dated speleothem stable oxygen isotope 18 o records although these speleothem 18 o signals provide useful evidence for regional past environmental changes their validity for denoting asm intensity remains a great controversy the huguangyan maar lake hml provides one of the most complete archives of environmental and climatic changes in the tropical subtropical south and east asia since the last glaciation here we document a continuous centennial to millennial scale asm record over the past 16 ky bp from the high sedimentation rate hml sediments in contrast with the low amplitude variations of chinese speleothem derived 18 o signals and the chinese loess based monsoon precipitation proxy indexes our multi proxy records reveal a pattern of high amplitude regional climatic fluctuations including fine scale oscillations during the bolling allerod warming the 8 2 ka cooling event and an abrupt climate shift from 6 5 5 9 ka the existence of bond like cold dry events indicates a distinct influence of the north atlantic circulation on low latitude monsoon changes the broad comparability between the hml paleo proxies chinese speleothem 18 o records and the northern hemisphere summer insolation throughout the holocene suggests that solar insolation exerts a profound influence on asm changes these findings reinforce a model of combined insolation and glacial forcing of the asm

concordant monsoon driven postglacial hydrological changes in peat and stalagmite records and their impacts on prehistoric cultures in central china asian monsoon records are widely documented but specific proxies of monsoonal rainfall are limited we present here two new independent proxy records from peatland and stalagmite archives that indicate a high degree of concordance between monsoon driven hydrological changes occurring since the last deglaciation in a broad region of central china the wet periods elevated the water table in the dajiuhu peatland as recorded by reduced mass accumulation rates of hopanoids biomarkers for aerobic microbes confirmed by molecular phylogenic analyses the hopanoid based reconstruction is supported by the first report of the environmental magnetism parameter arm sirm anhysteretic remanent magnetization saturation isothermal remanent magnetization ratio of fine magnetic particles to total ferrimagnetic particles in a stalagmite from heshang cave in central china heavy rainfall resulted in the enhanced transport of coarse particles to the cave and thus low arm sirm values in the stalagmite the hydrological conditions inferred from the two records reveal three relatively long wet periods in central china 13 11 5 k y ago 9 5 7 0 k y ago and 3 0 1 5 k y ago archaeological evidence for the hydrological impacts on regional populations comes from the observation that temporal shifts among six distinctive cultures of the neolithic period to the iron age in central china occurred during wet periods or flood episodes spatiotemporal distributions of 1600 prehistoric settlement sites correlate with the proxy inferred fluctuating hydrological conditions with enhanced flooding risk forcing major relocations of human settlements away from riparian zones

pollen record of the mid to late holocene centennial climate change on the east coast of south korea and its influential factors abstract to understand historical climate change in western pacific coastal areas a sediment core soj 2 from the stable sedimentary environment of the songjiho lagoon on the east coast of south korea was obtained for centennial resolution palynological analysis the ages of the soj 2 core is well controlled by carbon 14 dating with high resolution accelerator mass spectrometry ams and the results indicated a general warm to cold climate trend from the mid holocene to the present which can be divided into two different stages a warmer stage between 6842 and 1297 cal yr bp and a colder stage from 1297 cal yr bp to the present with fluctuations during these stages the climate was wetter from 6842 to 6227 cal yr bp and 4520 to 1297 cal yr bp and was drier from 6227 to 4520 cal yr bp the climate changed to cold and dry during the period from 1297 425 cal yr bp the impact of human activity on the climate began at approximately 1297 cal yr bp and became pronounced starting in 425 cal yr bp the general cooling trend may represent a response to decreasing solar insolation however the relative dryness or wetness of the climate may have been co determined by westerlies and the east asian summer monsoon easm the climate had a teleconnection with the north atlantic region resulting from changes in solar activity nevertheless ei nino southern oscillation enso activity played an important role in impacting the easm changes in western pacific coastal areas

osl dating of a holocene loess paleosol sequence in the southern loess plateau china optically stimulated luminescence osl dating of polymineral fine grained loess samples collected from the southern loess plateau of china was conducted using the single aliquot regenerative dose sar protocol a double sar procedure in which aliquots are subjected to both infrared ir and blue stimulations was used and two sets of equivalent dose d e determinations were produced these doses are assumed to be predominantly related to the feldspathic and quartz fine grain populations respectively the results revealed that the osl ages estimated by infrared stimulated luminescence irsl signals and those estimated by post ir stimulated luminescence post ir osl signals disagreed specifically the ages estimated using the irsl signals were smaller than those estimated using post ir osl signals the results of an anomalous fading test of the two types of osl signals revealed that the post ir osl signals from the etched sub sample by h2sif6 and hf and the un etched sub sample did not fade significantly however the irsl signals from the un etched sub sample showed obvious signs of fading these findings indicate that the lower age estimated by irsl is due to the anomalous fading of feldspar ir signals in the polymineral fine grains for samples collected from greater than 100 cm the estimates of their osl ages using two types of luminescence signals generally agreed with their pre estimated ages especially those of the post ir osl signals however for the three samples that were collected from a depth of less than 100 cm their osl ages were remarkably underestimated possibly due to the enhanced human activity such as soil cultivation that has occurred in the region since 3000 a b p

links between early holocene ice sheet decay sea level rise and abrupt climate change the beginning of the holocene interglacial was marked by ice sheet melting and sea level rise a review of sea level and climate records identifies two sea level jumps associated with the final drainage of glacial lake agassiz and links them to an abrupt cooling event

global glacial isostasy and the surface of the ice age earth the ice 5g vm2 model and grace abstract the 100 kyr quasiperiodic variation of continental ice cover which has been a persistent feature of climate system evolution throughout the most recent 900 kyr of earth history has occurred as a consequence of changes in the seasonal insolation regime forced by the influence of gravitational n body effects in the solar system on the geometry of earth s orbit around the sun the impacts of the changing surface ice load upon both earth s shape and gravitational field as well as upon sea level history have come to be measurable using a variety of geological and geophysical techniques these observations are invertible to obtain useful information on both the internal viscoelastic structure of the solid earth and on the detailed spatiotemporal characteristics of glaciation history this review focuses upon the most recent advances that have been achieved in each of these areas advances that have proven to be central to the construction of the refined model of the global process of glacial isos

glacial interglacial indian summer monsoon dynamics the modern indian summer monsoon ism is characterized by exceptionally strong interhemispheric transport indicating the importance of both northern and southern hemisphere processes driving monsoon variability here we present a high resolution continental record from southwestern china that demonstrates the importance of interhemispheric forcing in driving ism variability at the glacial interglacial time scale as well interglacial ism maxima are dominated by an enhanced indian low associated with global ice volume minima in contrast the glacial ism reaches a minimum and actually begins to increase before global ice volume reaches a maximum we attribute this early strengthening to an increased cross equatorial pressure gradient derived from southern hemisphere high latitude cooling this mechanism explains much of the nonorbital scale variance in the pleistocene ism record