quantifying climatic change through the last glacial interglacial transition based on lake isotope palaeohydrology from central turkey questions remain as to the nature of climatic change through the last glacial interglacial transition in the eastern mediterranean region particularly the relative contribution of evaporation and precipitation to regional water balance here changes in oxygen isotope values through this time period from eski acigol a crater lake in central turkey are investigated using hydrological and isotope mass balance models these allow changes in evaporation and precipitation to be quantified and their relative importance evaluated we show that it is the volumetric flux rate of water passing through the lake system and not the precipitation to evaporation ratio per se which controlled the stable isotope record in eski acigol early holocene precipitation is shown to be much greater than that during both the latter part of the last glaciation and the present day we test these calculated values against other records in the same region firstly with other lake records in anatolia the konya basin and lake van and secondly with isotope inferred palaeo precipitation data from soreq cave in israel this reveals a contrast between pre and post lgm precipitation values in turkey wetter and drier respectively and also suggests that during the last glacial interglacial transition there was a more marked precipitation gradient than at present between northern interior and southern coastal parts of the eastern mediterranean region

links between marine and atmospheric processes oscillating on a millennial time scale a multi proxy study of the last 50 000 yr from the alboran sea western mediterranean sea abstract the large dataset obtained from the extensive study of images core md95 2043 recovered from the alboran sea western mediterranean shows the periodicities and phase relationships of oceanographic and atmospheric processes on a millennial time scale the 1470 yr cycle is the most significant with the exception of the records reflecting climatic or environmental changes on land which show statistically significant 3300 and 8000 frequency bands the investigation of these core records on a millennial scale resolution allows us to establish the evolution of oceanographic and atmospheric mechanisms that influenced the western mediterranean region in the course of the dansgaard oeschger cycles accordingly possible land sea interactions can be identified and situated in the context of the temporal succession of the different climatic processes for instance saharan dust supply from northern africa appears to lead high latitude climate changes suggesting that low latitude feedback processes were involved in forcing the millennial climatic variability in the westernmost mediterranean

stable isotope records of late quaternary climate and hydrology from mediterranean lakes the isomed synthesis lake isotope records can be used to assess the spatial coherency of late quaternary climate change across the circum mediterranean region we place modern and palaeo data within a simple conceptual lake response model to show that the isotope hydrology of most mediterranean lakes has been influenced strongly by water balance even in those systems that are chemically dilute i e freshwater 18o data on biogenic and endogenic carbonates from 24 lake basins are used to reconstruct multi millennial scale trends since the lgm while it is difficult to make direct comparisons between lake records in terms of single climatic parameters coherent regional isotopic trends can be identified during glacial times mediterranean lakes deposited carbonates isotopically heavier in 18o compared to the holocene partly due to source area effects isotopic enrichment was most marked during intervals corresponding to the h1 and younger dryas events confirming that late pleistocene cold stages in the north atlantic region were marked by aridity around much of the mediterranean almost all mediterranean lake records shifted to more depleted isotopic values during the last glacial interglacial transition lgit this shift is the reverse of the trend which characterised the same transition in lakes from northern and central europe and suggests that temperature changes were not an important direct driver of mediterranean lake isotopic records over glacial interglacial timescales in the early holocene many lakes in the eastern part of the region were more depleted isotopically than in recent millennia this corresponds with marine sapropel formation both chronologically and geographically and implies that increases in local rainfall contributed significantly to the creation of a freshwater lid and anoxia in the east mediterranean sea in contrast no such pattern is currently apparent from lake isotope records from the west mediterranean suggesting a possible nw se contrast in climate history during the holocene

multi proxy speleothem record of climate instability during the early last interglacial in southern turkey abstract a stalagmite from dim cave in southern turkey contains a climate record documenting rapid and significant changes in amounts of precipitation between 132 ka and 128 ka during the penultimate glacial interglacial transition some u th dates have been compromised by carbonate dissolution but rigorous selection and tuning to 18o records from other speleothems has generated a robust age model growth rate was initially very slow but a rapid increase at 129 ka was accompanied by strong negative trends in 18o and 13c a combination implying the onset of much wetter conditions isotopic values at 129 ka suggest that groundwater recharge rates and biogenic activity in the soil zone exceeded those of the early holocene a significant isotopic enrichment event at 128 ka during which there was alternating aragonite and calcite deposition documents a strong drying event with a duration of 200 years a concurrent decrease in 87sr 86sr ratios indicates increased groundwater residence times and the cumulative evidence suggests amounts of rainfall fell from well above to slightly below present day levels similar 18o enrichment events are present in coeval speleothem records from southwest france and the northern alps and these together with pollen evidence from italy greece and the iberian margin of drier conditions at this time imply that a climate anomaly extended across the northern mediterranean borderlands the timing duration and structure of this episode are consistent with marine evidence of strong north atlantic cooling early in the last interglacial and there is a resemblance to the holocene 8 2 ka event recorded globally in many proxy climate archives

calibration of the calcite water oxygen isotope geothermometer at devils hole nevada a natural laboratory abstract the 18 o of ground water 13 54 0 05 and inorganically precipitated holocene vein calcite 14 56 0 03 from devils hole cave 2 in southcentral nevada yield an oxygen isotopic fractionation factor between calcite and water at 33 7 c of 1 02849 0 00013 1000 ln calcite water 28 09 0 13 using the commonly accepted value of calcite water t of 0 00020 k 1 this corresponds to a 1000 ln calcite water value at 25 c of 29 80 which differs substantially from the current accepted value of 28 3 use of previously published oxygen isotopic fractionation factors would yield a calcite precipitation temperature in devils hole that is 8 c lower than the measured ground water temperature alternatively previously published fractionation factors would yield a 18 o of water from which the calcite precipitated that is too negative by 1 5 using a temperature of 33 7 c several lines of evidence indicate that the geochemical environment of devils hole has been remarkably constant for at least 10 ka accordingly a re evaluation of calcite water oxygen isotopic fractionation factor may be in order assuming the devils hole oxygen isotopic value of calcite water represents thermodynamic equilibrium many marine carbonates are precipitated with a 18 o value that is too low apparently due to a kinetic isotopic fractionation that preferentially enriches 16 o in the solid carbonate over 18 o feigning oxygen isotopic equilibrium

dansgaard oeschger and heinrich event imprints in alboran sea paleotemperatures past sea surface temperature sst evolution in the alboran sea western mediterranean during the last 50 000 years has been inferred from the study of c37 alkenones in international marine global change studies md952043 core this record has a time resolution of 200 years allowing the study of millennial scale and even shorter climatic changes the observed sst curve displays characteristic sequences of extremely rapid warming and cooling events along the glacial period comparison of this alboran record with 18o from greenland ice greenland ice sheet project 2 core shows a strong parallelism between these sst oscillations and the dansgaard oeschger events five prominent cooling episodes standing out in the sst profile are accompanied by an anomalous high abundance of neogloboquadrina pachyderma sinistral which is confined to the duration of these cold intervals these features and the isotopic record reflect drastic changes in the surface hydrography of the alboran sea in association with heinrich events hl 5

abrupt changes of temperature and water chemistry in the late pleistocene and early holocene black sea new mg ca sr ca and published stable oxygen isotope and 87sr 86sr data obtained on ostracods from gravity cores located on the northwestern black sea slope were used to infer changes in the black sea hydrology and water chemistry for the period between 30 to 8 ka b p calibrated radiocarbon years the period prior to 16 5 ka b p was characterized by stable conditions in all records until a distinct drop in 18o values combined with a sharp increase in 87sr 86sr occurred between 16 5 and 14 8 ka b p this event is attributed to an increased runoff from the northern drainage area of the black sea between heinrich event 1 and the onset of the bolling warm period while the mg ca and sr ca records remained rather unaffected by this inflow they show an abrupt rise with the onset of the bolling allerod warm period this rise was caused by calcite precipitation in the surface water which led to a sudden increase of the sr ca and mg ca ratios of the black sea water the stable oxygen isotopes also start to increase around 15 ka b p although in a more gradual manner due to isotopically enriched meteoric precipitation while sr ca remains constant during the following interval of the younger dryas cold period a decrease in the mg ca ratio implies that the intermediate water masses of the black sea temporarily cooled by 1 2 c during the younger dryas the 87sr 86sr values drop after the cessation of the water inflow at 15 ka b p to a lower level until the younger dryas where they reach values similar to those observed during the last glacial maximum this might point to a potential outflow to the mediterranean sea via the sea of marmara during this period the inflow of mediterranean water started around 9 3 ka b p which is clearly detectable in the abruptly increasing mg ca sr ca and 87sr 86sr values the accompanying increase in the 18o record is less pronounced and would fit to an inflow lasting 100 a

paleoglacial records from kavron valley ne turkey field and cosmogenic exposure dating evidence abstract kavron valley lies in the kackar mountain range of northeastern anatolia and is a north south oriented typically u shaped glacial valley consisting of a main and three tributary valleys the quaternary units that outcrop in this valley have been mapped and 22 samples have been processed for surface exposure dating using cosmogenic 10 be according to the 10 be ages the advance of the kavron paleoglacier began at least 26 0 1 2 kyr ago with the last glacial maximum lgm advance continuing until 18 3 0 9 kyr after this time the kavron paleoglacier receded although the magnitude of this recession is still unknown subsequent to this retreat the glacier most probably separated into three smaller glaciers that were restricted to the tributary valleys ifrit derebasi and mezovit paleoglaciers the main valley was definitely ice free by 15 5 0 7 kyr ago with the mezovit paleoglacier completing its recession around 15 5 0 6 kyr a late glacial advance took place around 13 0 0 8 to 11 5 0 8 kyr and little ice age moraines appear to be absent our results from the kavron valley system seem to be consistent with the lgm paleoclimate record of anatolia which has been delineated by data gathered from lowlands and lakes the deposition of red clay layers in the northwestern black sea and the deposition of heinrich 1 layers in the north atlantic

climate and vegetation history of the midcontinent from 75 to 25 ka a speleothem record from crevice cave missouri usa four missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago ka the thorium 230 dated records reveal that between 75 and 55 ka the midcontinental climate oscillated on millennial time scales between cold and warm and vegetation alternated among forest savanna and prairie temperatures were highest and prairie vegetation peaked between 59 and 55 ka climate cooled and forest replaced grassland at 55 ka when global ice sheets began to build during the early part of marine oxygen isotope stage 3

cold and wet last glacial maximum on mount sandiras sw turkey inferred from cosmogenic dating and glacier modeling abstract in situ cosmogenic 36 cl was measured in boulders from moraines on mount sandiras 37 1 n 28 8 e 2295 m the southwestern most previously glaciated mountain in turkey valleys on the north side of the mountain were filled with 1 5 km long glaciers that terminated at an altitude of 1900 m the glacial activity on mount sandiras correlates with the broadly defined last glacial maximum lgm the maximum glaciation occurred approximately 20 4 1 3 ka 1 1 ka 1000 calendar years ago when glaciers started retreating and the most extensive moraines were deposited the glaciers readvanced and retreated by 19 6 1 6 ka ago and then again by 16 2 0 5 ka using the glacier modeling and the paleoclimate proxies from the eastern mediterranean we estimated that if temperatures during lgm were 8 5 11 5 c lower than modern precipitation was up to 1 9 times more than that of today thus the local lgm climate was cold and wet which is at odds with the conventional view of the lgm as being cold and dry in the region

sea rain lake relation in the last glacial east mediterranean revealed by δ18o δ13c in lake lisan aragonites we investigated the sea rain lake relation during the last glacial holocene in the east med iterranean region by comparing the 18 o and 13 c records of authigenic aragonite deposited in lake lisan the dead sea mediterranean foraminifera and speleothems the lisan formation data display long and short term variations of 18 o representing steady state conditions of the lake e g 5 6 0 5 and 4 5 1 in the upper and lower members of the lisan formation respectively and short term excursions reflecting large floods and droughts the long term steady state 18 o values of the lisan aragonites show similarity to the corresponding time equivalent records of the eastern mediterranean foraminifera and judea mountain speleothems the last glacial deposits are in all of them 2 3 heavier than the holocene ones we interpret this similarity as reflecting the significance of the source effect on the long term behavior of isotopic reservoirs speleothem 18 o is strongly influenced by the marine reservoir that contributes its vapor to rain formation the lake 18 o is dominated by the composition of the inflowing water short term variations in the isotopic composition of rainfall are dominated by the amount effect and the temperature and those of the lake s upper water mass by the lake s water balance 13 c values are more variable than 18 o in the same lisan sequences e g 13 c in the lower member is 1 0 1 7 whereas 18 o is 4 6 0 7 and are 1 to 1 5 higher in the upper member than in the lower and middle members of the lisan formation these variations reflect significant increase in primary productivity of the lake and algal bloom activity it appears that the hypersaline saline lakes were not as dead as the dead sea is and that algal activity had an important impact upon the geochemistry of lake lisan the 18 o data combined with independent geochemical and limnologic information e g level fluctuations indicate that lisan time was characterized by high precipitation high lake stands high atmospheric humidity whereas the holocene dead sea shows the opposite behavior this paleoclimatic reconstruction is consistent with independent evidence for significantly wetter conditions in the east mediterranean region during the last glacial period copyright 2005 elsevier ltd

late quaternary paleoclimate in the eastern mediterranean region from stable isotope analysis of speleothems at soreq cave israel abstract the eastern mediterranean continental paleoclimate during the past 25 000 years was determined by a high resolution petrographic stable isotopic and age study of speleothems from soreq cave israel 18o 13c trends indicate that all speleothems older than 7000 yr formed under conditions that differ from those of today the period from 25 000 to 17 000 yr b p was characterized by the highest 18o and 13c values which indicate deposition at temperatures of 12 16 c annual rainfall of 300 450 mm and vegetation typical of a mixed c3 c4type from 17 000 to 10 000 yr b p deglaciation in northern europe 18o values dropped progressively correlative with warming 2 3 c and a gradual increase in precipitation a simultaneous decrease in 13c gives a range expected for c3 type vegetation this period also shows significant 18o and 13c spikes which are correlatable with global events e g heinrich events and the younger dryas stade the speleothems that grew between 10 000 and 7000 yr b p have a unique petrography showing irregular thin laminae of various colors and much detritus they have the lowest 18o corresponding to 1000 mm rain coupled with the highest 13c caused by flooding events which stripped the soil cover from 7000 to 1000 yr b p conditions became closer to those of today this study demonstrates that global events which were recognized in northern europe and north africa are also evident in the eastern mediterranean and are reflected principally by large changes in the rainfall rate

calcite fabrics growth mechanisms and environments of formation in speleothems from the italian alps and southwestern ireland five fabrics were identified in alpine and irish caves on the basis of morphological and microstructural characteristics and re lated to growth mechanisms and growth environment columnar and fibrous fabrics grow when speleothems are continuously wet and from fluids at near equilibrium conditions low supersaturation sicc 0 35 through the screw dislocation mechanism the highly defective microcrystalline fabrics form at the same supersaturation range as co lumnar fabric but under variable discharge and the presence of growth inhibitors dendritic fabrics which have the highest density of crystal defects develop in disequilibrium conditions high supersaturation un der periodic very low flow regime periods that result in prolonged out gassing cave calcareous tufa forms in disequilibrium conditions only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near isotopic equilibrium conditions

deciphering the palaeoecology of late pliocene and early pleistocene dinoflagellate cysts abstract in an attempt to document the palaeoecological affinities of individual extant and extinct dinoflagellate cysts late pliocene and early pleistocene dinoflagellate cyst assemblages have been compared with geochemical data from the same samples mg ca ratios of globigerina bulloides were measured to estimate the spring summer sea surface temperatures from four north atlantic iodp dsdp sites currently our pliocene pleistocene database contains 204 dinoflagellate cyst samples calibrated to geochemical data this palaeo database is compared with modern north atlantic and global datasets the focus lies in the quantitative relationship between mg ca based i e spring summer sea surface temperatures sstmg ca and dinoflagellate cyst distributions in general extant species are shown to have comparable spring summer sst ranges in the past sstmg ca and today sst from world ocean atlas 2005 locarnini et al 2006 demonstrating that our new approach is valid for inferring spring summer sst ranges for extinct species for example habibacysta tectata represents sstmg ca values between 10 and 15 c when it exceeds 30 of the assemblage and invertocysta lacrymosa exceeds 15 when sstmg ca values are between 18 6 and 23 5 c however comparing pliocene and pleistocene sstmg ca values with present day summer values for the extant impagidinium pallidum suggests a greater tolerance of higher temperatures in the past this species occupies more than 5 of the assemblage at sstmg ca values of 11 6 17 9 c in the pliocene and pleistocene whereas present day summer ssts are around 1 7 to 6 9 c this observation questions the value of impagidinium pallidum as reliable indicator of cold waters in older deposits and may explain its bipolar distribution

rapid environmental changes in southern europe during the last glacial period oxygen isotope records from greenland ice cores1 2 indicate numerous rapid climate fluctuations during the last glacial period north atlantic marine sediment cores show comparable variability in sea surface temperature and the deposition of ice rafted debris3 4 5 in contrast very few continental records of this time period provide the temporal resolution and environmental sensitivity necessary to reveal the extent and effects of these environmental fluctuations on the continents here we present high resolution geochemical physical and pollen data from lake sediments in italy and from a mediterranean sediment core linked by a common tephrochronology our lacustrine sequence extends to the past 102 000 years many of its features correlate well with the greenland ice core records demonstrating that the closely coupled ocean atmosphere system of the northern hemisphere during the last glacial4 extended its influence at least as far as the central mediterranean region numerous vegetation changes were rapid frequently occurring in less than 200 years showing that the terrestrial biosphere participated fully in last glacial climate variability earlier than 65 000 years ago our record shows more climate fluctuations than are apparent in the greenland ice cores together the multi proxy data from the continental and marine records reveal differences in the seasonal character of climate during successive interstadials and provide a step towards determining the underlying mechanisms of the centennial millennial scale variability

sea land oxygen isotopic relationships from planktonic foraminifera and speleothems in the eastern mediterranean region and their implication for paleorainfall during interglacial intervals the oxygen and carbon stable isotope compositions of cave speleothems provide a powerful method for understanding continental climate change here we examine the question of the regionality of this isotopic record and its linkage with the marine isotopic record in the eastern mediterranean em region the study presents a new accurately dated 250 kyr 18o and 13c record determined from speleothems of the peqiin cave northern israel its comparison with the continuous 185 kyr isotopic record of the soreq cave speleothems from central israel reveals striking similarities thus a strong regional climatic signal brought about by variations in temperature and rainfall amount is reflected in both cave records low 18o minima in the peqiin profile for the last 250 to 185 kyr period interglacial marine isotopic stage 7 match the timing of sapropels 9 to 7 and are indicative of high rainfall in the em region at these times the combined soreq and peqiin 18o record for the last 250 kyr excellently matches the published globigerinoides ruber g ruber marine 18o record for the em sea with the isotopic compositional difference g ruber speleothems remaining relatively constant at 5 6 0 7 thus establishing for the first time a robust exploitable link between the land and the marine isotopic records the correspondence of low 18o speleothem values and high cave water stands with low g ruber 18o values during interglacial sapropel events indicates that these periods were characterized by enhanced rainfall in the em land and sea regions by use of sea surface temperatures derived from alkenone data as a proxy for land temperatures at the soreq cave we calculate the paleorainfall 18o values and its amounts maximum rainfall and lowest temperature conditions occurred at the beginning of the sapropel events and were followed by decrease in rainfall and increase in temperatures leading to arid conditions the record for the last 7000 yr shows a trend toward increasing aridity and agrees well with climatic and archeological data from north africa and the middle east

monsoons and the dynamics of deserts the existence of subtropical deserts such as the sahara has often been attributed to the annual mean zonal mean hadley circulation which shows strong descent in the subtropics however the zonal mean hadley circulation shows considerable evolution over the course of the year with very strong subtropical descent during winter but practically no zonal mean subtropical descent during summer when rainfall over the eastern sahara and the mediterranean is least charney 1975 proposed a biosphere albedo feedback mechanism whereby local anthropogenic effects related to over grazing could affect the radiative balance enhancing summertime diabatic descent and leading to desertification of the subtropics in general the present study which uses an idealized model suggests a monsoon desert mechanism for desertification whereby remote diabatic heating in the asian monsoon region can induce a rossby wave pattern to the west integral with the rossby wave solution is a warm thermal structure that interacts with air on the southern flank of the mid latitude westerlies causing it to descend this adiabatic descent is localized over the eastern sahara and mediterranean and over the kyzylkum desert to the south east of the aral sea by the mountains of north africa and south west asia trajectories indicate that the monsoon desert mechanism does not represent a simple walker type overturning cell instead the descending air is seen to be mainly of mid latitude origin it is speculated that the monsoon forced adiabatic descent may result in clear air and therefore a local diabatic enhancement which effectively doubles the strength of descent with this mechanism desertification can be forced by remote changes in monsoon strength rather than by local effects this conclusion is supported by the observed dramatic strengthening of descent over the mediterranean and east sahara during the onset of the asian monsoon and on the longer timescale by relating prehistoric lake levels to milankovitch monsoon forcing the latter may help to explain the perceived discrepancies between the palaeoclimate of the eastern sahara and the strength of a tropic wide monsoon the monsoon desert mechanism may not be confined to the asian monsoon alone and the existence of other monsoon climate regions over the globe may in a similar way explain the observed summertime strengthening of the oceanic sub tropical anticyclones and the existence of western continental deserts and mediterranean type climate regions

orbital and sub orbital scale climate impacts on vegetation of the western mediterranean basin over the last 48 000 yr article i nfo high resolution pollen analysis of alboran sea core md95 2043 provides a 48 ka continuous vegetation record that can be directly correlated with sea surface and deep water changes the reliability of this record is supported by comparison with that of padul sierra nevada spain marine isotope stage mis 3 was characterised by fluctuations in quercus forest cover in response to dansgaard oeschger climate variability mis 2 was characterised by the dominance of semi desert vegetation despite overall dry and cold conditions during mis 2 heinrich events hes 2 and 1 were distinguished from the last glacial maximum by more intensely arid conditions taxon specific vegetation responses to a tripartite climatic structure within the hes are observed in mis 1 the bolling allerod was marked by rapid afforestation while a re expansion of semi desert environments occurred during the younger dryas the maximum development of mixed quercus forest occurred between 11 7 and 5 4 cal ka bp with forest decline since 5 4 cal ka bp on orbital timescales a long term expansion of semi desert vegetation from mis 3 into mis 2 reflects global ice volume trends while holocene arboreal decline reflects summer insolation decrease the influence of precession on the amplitude of forest development and vegetation composition is also detected

millennial to orbital scale variations of drought intensity in the eastern mediterranean abstract millennial to orbital scale rainfall changes in the mediterranean region and corresponding variations in vegetation patterns were the result of large scale atmospheric reorganizations in spite of recent efforts to reconstruct this variability using a range of proxy archives the underlying physical mechanisms have remained elusive through the analysis of a new high resolution sedimentary section from lake van turkey along with climate modeling experiments we identify massive droughts in the eastern mediterranean for the past four glacial cycles which have a pervasive link with known intervals of enhanced north atlantic glacial iceberg calving weaker atlantic meridional overturning circulation and dansgaard oeschger cold conditions on orbital timescales the topographic effect of large northern hemisphere ice sheets and periods with minimum insolation seasonality further exacerbated drought intensities by suppressing both summer and winter precipitation

glacial mediterranean sea surface temperatures based on planktonic foraminiferal assemblages we present a new reconstruction of mediterranean sea surface temperatures sst during the last glacial maximum lgm a calibration data set based on census counts of 23 species of planktonic foraminifera in 129 north atlantic and 145 mediterranean core top samples was used to develop summer winter and annual average sst reconstructions using artificial neural networks anns and the revised analogue method ram prediction errors determined by cross validation of the calibration data set ranged between 0 5 and 1 1 c with both techniques being most successful in predicting winter ssts glacial reconstructions are based on a new expanded data set of 273 samples in 37 cores with consistent minimum level of age control the new lgm reconstructions suggest that the east west temperature gradient during the glacial summer was 9 c whereas during the glacial winter the gradient was 6 c both some 4 c higher than that existing today in contrast to earlier studies our results tend to suggest much cooler sst estimates throughout the glacial mediterranean particularly in the eastern basin where previous sst reconstructions indicated a decrease of only 1 c our new sst reconstructions will provide the modelling community with a detailed and updated portrayal of the mediterranean sea during the lgm setting new targets on which glacial simulations can be tested

timing and climatic impact of greenland interstadials recorded in stalagmites from northern turkey a 50 kyr long exceptionally well dated and highly resolved stalagmite oxygen 18o and carbon 13c isotope record from sofular cave in northwestern turkey helps to further improve the dating of greenland interstadials gi 1 and 3 12 timing of most gi in the sofular record is consistent within 10 to 300 years with the iconic hulu cave record larger divergences 500 years between sofular and hulu are only observed for gi 4 and 7 the sofular record differs from the most recent ngrip chronology by up to several centuries whereas age offsets do not increase systematically with depth the sofular record also reveals a rapid and sensitive climate and ecosystem response in the eastern mediterranean to gi whereas a phase lag of 100 years between climate and full ecosystem response is evident finally results of spectral analyses of the sofular isotope records do not support a 1 470 year pacing of gi

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

continental oxygen isotopic record of the last 170 000 years in jerusalem abstract a long radiometrically dated oxygen isotopic record of continental climatic variations since the penultimate glaciation was obtained from a stalagmite deposited in a sealed cave in jerusalem this record shows that speleothems have the potential of assigning dates to long and short term climatic events with possible refining of milankovitch tuning of ice and marine records which themselves are not datable short term 1000 yr events are very significant in the region reaching 50 of glacial interglacial fluctuations the mediterranean sea was the most probable source of local precipitation throughout the last glacial cycle

towards an understanding of the response of southern european vegetation to orbital and suborbital climate variability abstract in recent years the generation of high resolution terrestrial and marine long pollen sequences with improved chronological control has provided new insights into the vegetation response in southern europe to orbital and suborbital climate variability here a synthesis of our current understanding of the phase and amplitude relationships between climate forcing and vegetation changes is presented what emerges is that on orbital frequencies the timing of interglacial forest expansion is closely linked to the summer insolation maximum but does not have a fixed lag relative to the mid point of the deglaciation which may vary from one termination to another for the closing phases of interglacials the available evidence suggests that forest in southern europe usually extends into the interval of ice growth however suborbital variability may override the diachronous relationship between glacial inception and forest decline leading to a premature ending of forest periods during glacial intervals there is a close correspondence between tree population size and ice volume extent while during temperate intervals the extent of forest development is closely related to the amplitude of insolation and associated climate regimes but may diverge from the extent of residual ice volume on suborbital frequencies changes in tree population size are in phase with climate forcing while the amplitude of these changes is modulated by geographical position and local factors finally orbital mean state can lead to the modulation of the amplitude of suborbital scale variability examination of additional climatic cycles and increased resolution better than 200 years are needed to test further these preliminary conclusions

pleistocene water intrusions from the mediterranean and caspian seas into the black sea the hydrological balance of the black sea is governed by riverine input and by the exchange with the mediterranean sea a speleothem record from a cave in northern turkey that tracks the isotopic signature of black sea surface water suggests an open connection to the mediterranean sea in at least twelve periods in the past 670 000 years

the last glacial termination a major puzzle of paleoclimatology is why after a long interval of cooling climate each late quaternary ice age ended with a relatively short warming leg called a termination we here offer a comprehensive hypothesis of how earth emerged from the last global ice age a prerequisite was the growth of very large northern hemisphere ice sheets whose subsequent collapse created stadial conditions that disrupted global patterns of ocean and atmospheric circulation the southern hemisphere westerlies shifted poleward during each northern stadial producing pulses of ocean upwelling and warming that together accounted for much of the termination in the southern ocean and antarctica rising atmospheric co2 during southern upwelling pulses augmented warming during the last termination in both polar hemispheres

regional synthesis of mediterranean atmospheric circulation during the last glacial maximum atmospheric circulation leaves few direct traces in the geological record making reconstructions of this crucial element of the climate system inherently difficult we produced a regional mediterranean synthesis of paleo proxy data from the sea surface to alpine altitudes this provides a detailed observational context for change in the three dimensional structure of atmospheric circulation between the last glacial maximum lgm 23 000 to 19 000 years ago and the present the synthesis reveals evidence for frequent cold polar air incursions topographically channeled into the northwestern mediterranean anomalously steep vertical temperature gradients in the central mediterranean imply local convective precipitation we find the lgm patterns to be analogous though amplified to previously reconstructed phases of enhanced meridional winter circulation during the maunder minimum the little ice age

speleothem isotopic evidence of winter rainfall variability in northeast turkey between 77 and 6 ka an oxygen isotope record from a stalagmite that grew between 77 ka and 6 ka in northeast turkey contains both a strong precessional signal and sub orbital oscillations similar to those in greenland ice cores and chinese speleothem records of monsoon intensity fluid inclusion evidence of a negative shift in the isotopic composition of dripwater during the lateglacial supports interpretation of the isotope curve as an insolation forced record of changes in rainfall seasonality the high amplitude millennial scale fluctuations are caused by rapid changes in rainfall seasonality and or switching of moisture source areas both of which are associated with the stadial interstadial climatic oscillations linked to the changing modes of the north atlantic meridional overturning circulation moc winter rainfall maxima in northeast turkey coincide with interstadial conditions in greenland and with periods of intensified asian monsoon activity the isotopic shifts in the record are in antiphase with and are generally much larger in amplitude than published data from stalagmites in northwest turkey most likely because of differing moisture source areas carbon isotope ratios are probably kinetically enriched by partial degassing of seepage water in the epikarst but although often difficult to decypher particularly during marine isotope stage mis 2 broadly support the interpretations of the oxygen data

high resolution greenland ice core data show abrupt climate change happens in few years the last two abrupt warmings at the onset of our present warm interglacial period interrupted by the younger dryas cooling event were investigated at high temporal resolution from the north greenland ice core project ice core the deuterium excess a proxy of greenland precipitation moisture source switched mode within 1 to 3 years over these transitions and initiated a more gradual change over 50 years of the greenland air temperature as recorded by stable water isotopes the onsets of both abrupt greenland warmings were slightly preceded by decreasing greenland dust deposition reflecting the wetting of asian deserts a northern shift of the intertropical convergence zone could be the trigger of these abrupt shifts of northern hemisphere atmospheric circulation resulting in changes of 2 to 4 kelvin in greenland moisture source temperature from one year to the next

stable isotope compositions of speleothems from the last interglacial spatial patterns of climate fluctuations in europe abstract studies on the last interglacial lig can provide information on how our environment behaved in a period of slightly higher global temperatures at about 125 4 ka even if it is not the best analogue for the holocene the available lig climate proxy records are usually better preserved and can be studied at a higher resolution than those of the preceding interglacials allowing detailed comparisons this paper presents complex stable hydrogen carbon and oxygen isotope records obtained for carbonate 13 c and 18 o carb and fluid inclusion hosted water d and 18 o w of a stalagmite from the baradla cave system in central europe that covers most of the lig as proven by u th dates comparing its c and o isotope data with records reported for other speleothem cave hosted carbonate deposits from europe revealed the complex behavior of these climate proxies with a concerted relative increase in 18 o of carbonates from 128 to 120 ka and synchronized shifts in the opposite direction after 119 ka the hydrogen isotope analyses of inclusion hosted water extracted from the bar ii stalagmite also correspond to the regional climate proxy records with meaningful deviations from global temperature trends beside following the general paleotemperature pattern from the climate optimum high d values up to 64 around 120 ka to the subsequent cooling starting at about 119 ka low d values down to 90 at about 109 ka a period between 126 5 and 123 ka with low d values down to 81 is detected in the bar ii stalagmite although the isotope shifts are muted in the c o isotope data of carbonate due to competitive fractionation processes the 13 c data show a positive relationship with the d pattern indicating humidity and possibly temperature variations the periods with low d values fit well to temperature and humidity changes inferred from proxy records from western europe to the eastern mediterranean spatial distributions of these variables show that at about 125 2 ka the mediterranean region was characterized by warm humid conditions and enhanced seasonality with elevated winter precipitation the combined interpretation of stable isotope data revealed that the alpine and mediterranean regions behaved differently during greenland stadial 26 gs26 119 to 116 2 ka while the alpine records fluctuated in close agreement with the central greenland ice core 18 o data the bar ii stalagmite show a positive 18 o carb anomaly the baradla data indicate enhanced aridity and seasonality for a part of gs26 with the relative dominance of summer precipitation and mediterranean moisture contribution following the gs26 event the effect of long term global cooling becomes dominant in the baradla isotope records and leads to glacial inception at about 109 ka

indian ocean climate and an absolute chronology over dansgaard oeschger events 9 to 13 oxygen isotope ratios of a stalagmite from socotra island in the indian ocean provide a record of changes in monsoon precipitation and climate for the time period from 42 to 55 thousand years before the present the pattern of precipitation bears a striking resemblance to the oxygen isotope record from greenland ice cores with increased tropical precipitation associated with warm periods in the high northern latitudes the largest change at the onset of interstadial 12 occurred very rapidly in about 25 years the chronology of the events found in our record requires a reevaluation of previously published time scales for climate events during this period

late pleistocene variability of the carbon isotopic composition of organic matter in the eastern mediterranean monitor of changes in carbon sources and atmospheric co2 concentrations the organic carbon isotopic record of the sapropels s1 and s3 s10 and intercalated marl oozes has been determined in a 12 m piston core from the eastern mediterranean the 13corganic values are systematically lighter mean 21 0 0 82 in all sapropels and heavier mean 18 8 1 07 in the marl oozes these differences are not due to variable marine and terrestrial organic matter mixtures because all values are heavier than modern plankton in the mediterranean there is no relationship between the corganic n ratios and the isotopic values and published information on the abundance and distribution of organic biomarkers shows that terrestrial material constitutes a minor fraction of the total organic matter temperature effects on isotope fractionation are also discounted because the change in 13corganic values between glacial and interglacial horizons is in the opposite sense diagenesis which can produce relatively small changes in the carbon isotopic composition of sedimentary organic matter under certain circumstances is unlikely to have caused the observed differences because this mechanism would cause an enrichment in 12c implying that all values were even heavier originally and there is no secular trend in the 13corganic record the observed differences in 13corganic between the two lithologies are probably produced by changes in the isotopic composition and the concentration of dissolved co2 first freshwater flooding during the formation of the sapropels caused the isotopic composition of the dissolved inorganic carbon in the surface waters of the mediterranean to become lighter because of the 13c deficiency in fresh waters hence photosynthesis would have produced isotopically lighter organic material second changes in atmospheric pco2 between glacial and interglacial periods as shown by the vostok ice core caused marked changes in the concentration of free dissolved co2 in the mixed layer lower values during glacial maxima caused a smaller fractionation of the carbon isotopes by phytoplankton whereas levels were less limiting during the interglacials concentrations of dissolved co2 could also have been much higher during the deposition of the sapropels because of the supply of regenerated co2 to the mixed layer by upwelling and this could have further lightened the 13corganic values in the sapropels themselves carbon isotope records may provide an alternative method for estimating atmospheric pco2 levels over longer time periods than can be obtained from ice cores

mid holocene climate variations revealed by high resolution speleothem records from soreq cave israel and their correlation with cultural changes mid holocene 7000 4000 yr bp paleoclimate conditions were reconstructed for the eastern mediterranean region through a high resolution 3 20 yr oxygen and carbon isotopic record in a speleothem

climatic variability during the last 90 ka of the southern and northern levantine basin as evident from marine records and speleothems abstract the influence of the northern atlantic and tropical monsoonal systems as recorded by the river nile on the climate variability of the southeastern mediterranean was studied in two cores taken by the r v marion dufresne one core taken se of cyprus representing the northern levantine basin core 9501 980 m water depth and the other located 380 km further south represents the southeastern levantine basin in an area influenced by the river nile plume core 9509 884 m water depth the study was performed at relatively high resolution using several proxies 18o of globigerinoides ruber sediment characteristics and index colour parameters in core sections representing the last 86 ka a low resolution alkenone sea surface temperature record was also measured the time frame in both cores was mostly constrained by wiggle matching with the nearby well dated 18o and 13c record of the soreq cave which is mainly influenced by the eastern mediterranean water vapor the sedimentary record of the southern core is strongly influenced by the river nile contribution throughout the last 86 ka as evidenced by the higher sedimentation rates compared with the northern core 20 cm ka vs 5 cm ka continuously darker sediment colour and higher toc values 0 6 0 9 vs 0 25 wt not including sapropels during sapropels s1 and s3 present in both cores the influence of the river nile became more widespread reaching as far as cyprus yet the influence of the river nile remained stronger in the south as evident by the higher toc values in the southern core throughout the entire 90 ka period and the longer duration of s1 in the southern core an anomalous low 18o interval that is not recorded in western mediterranean occurred between 58 and 49 ka in the levantine basin and is more developed in the northern core this period correlates with d o interstadial 14 and maximum northern hemisphere insolation during the lastglacial cycle suggesting that the warming mainly impacted the northern levant the eastern mediterranean sea and land area was considerably warmer than the western mediterranean throughout the lgm holocene transition and the 18og ruber drop of 4 5 is significantly greater than the 3 shift found for the western mediterranean 18og bulloides both differences reflecting an increased continental effect from the western to eastern mediterranean comparison between the marine and the land 18o records suggests that the origin of rain over the land is composed of mixed signal from the southern and northern levantine basin the study of 18osea land variations demonstrates that various factors have influenced the sea land relationship during the last 90 ka the amount effect has an important influence on rainfall 18o during interglacial periods particularly sapropel periods whereas during glacial periods increased land distances and elevation differences arising from decrease in sea level may have brought about decrease in 18o of rainfall due to rayleigh distillation processes these influences were superimposed on those of sea surface water 18o changes brought about by continental ice melting and the strong effects felt in the southern levantine basin of the high river nile input during periods of enhanced monsoonal activity

the last climatic cycle at kopais central greece thick lacustrine sequences from southern europe provide an opportunity to derive continuous records where the chronostratigraphical position of pre holocene stages can be determined with increased confidence here high resolution sediment and pollen analytical results from a 60 m core recovered from the kopais basin central greece spanning the interval from the last interglacial to the early holocene are presented the record shows distinct shifts between open vegetation periods of increased erosion with sediment inwashing and forest periods associated with calcite precipitation in the lake the sequence of major events of the last climatic cycle contained at kopais bears strong similarities to other records in greece but also reveals the presence of high frequency oscillations with higher amplitudes than previously seen at other sites

holocene climate and cultural evolution in late prehistoric early historic west asia abstract the precipitation climatology and the underlying climate mechanisms of the eastern mediterranean west asia and the indian subcontinent are reviewed with emphasis on upper and middle tropospheric flow in the subtropics and its steering of precipitation holocene climate change of the region is summarized from proxy records the indian monsoon weakened during the holocene over its northernmost region the ganges and indus catchments and the western arabian sea southern regions the indian peninsula do not show a reduction but an increase of summer monsoon rain across the holocene the long term trend towards drier conditions in the eastern mediterranean can be linked to a regionally complex monsoon evolution abrupt climate change events such as the widespread droughts around 8200 5200 and 4200 cal yr bp are suggested to be the result of altered subtropical upper level flow over the eastern mediterranean and asia the abrupt climate change events of the holocene radically altered precipitation fundamental for cereal agriculture across the expanse of late prehistoric early historic cultures known from the archaeological record in these regions social adaptations to reduced agro production in both dry farming and irrigation agriculture regions are visible in the archaeological record during each abrupt climate change event in west asia chronological refinement in both the paleoclimate and archaeological records and transfer functions for both precipitation and agro production are needed to understand precisely the evident causal linkages

quaternary geochronology using the uthpb method abstract we describe a method of uranium thorium lead u th pb isotopic age dating for quaternary rocks the approach uses an instrumental mass discrimination correction for lead isotope ratios which allows small enrichments of radiogenic 206ph and 208ph to be detected at the level of 0 001 igneous rocks hosting minerals with a range in 238 u 204 pb values of 100 can be dated with uncertainties of approximately 15 20 kyr a quaternary rhyolite dated at 1 19 ma by k ar yields a 238u 206ph age of 1 03 0 10 ma a holocene dacite 9 5 ka has uniform 206 pb 207 pb to within 0 0015 in groundmass phases but 1 mm plagioclase phenocrysts have lower 206 pb 207 pb by 0 105 0 002 indicating contamination of the magma after plagioclase crystallization high precision 206 pb 207 ph ratios may be a useful new tool for petrogenetic studies

evidence for enhanced mediterranean thermohaline circulation during rapid climatic coolings molecular biomarkers c37 alkenones n nonacosane and n hexacosanol and toc are used together with benthic 18o and 13c data to document the hydrographic response of the western mediterranean sea to rapid climatic variability these proxies are recorded in core md 95 2043 alboran sea affording the study of the dansgaard oeschger d o and heinrich he variability during the last glacial period the results suggest that rapid changes in the western mediterranean thermohaline circulation occurred in parallel to sea surface temperature oscillations enhanced deep water ventilation occurred during cold intervals he and d o stadials probably driven by a strengthening of north westerly wind over the north western mediterranean sea in contrast decreased intensity of the thermohaline circulation is detected during warm intervals d o interstadials which led to low oxygenated deep water masses and better preservation of the organic matter in the sediment

mediterranean vegetation lake levels and palaeoclimate at the last glacial maximum the apparent conflict between pollen evidence for widespread artemisia steppe1 6 implying semi arid conditions and geomorphological evidence for high lake levels4 7 11 has produced controversy about the ice age palaeoclimate of the mediterranean region here we use a water balance model12 to predict catchment runoff and a biome model13 to predict vegetation type to reconstruct the palaeoenvironment around lake loannina a type locality for the northern mediterranean region we show that both sets of evidence are compatible with a summer dry winter wet regime with seasonal temperature anomalies similar to those predicted by atmospheric model simulations of the last glacial maximum14 18 the drying effect of the cold north atlantic ocean may have been counteracted in winter by increased storm frequency under a southward shifted jet stream as shown by several atmospheric models16 18

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

synchronous timing of abrupt climate changes during the last glacial period abrupt climate changes during the last glacial period have been detected in a global array of palaeoclimate records but our understanding of their absolute timing and regional synchrony is incomplete our compilation of 63 published independently dated speleothem records shows that abrupt warmings in greenland were associated with synchronous climate changes across the asian monsoon south american monsoon and european mediterranean regions that occurred within decades together with the demonstration of bipolar synchrony in atmospheric response this provides independent evidence of synchronous high latitude to tropical coupling of climate changes during these abrupt warmings our results provide a globally coherent framework with which to validate model simulations of abrupt climate change and to constrain ice core chronologies

from pleniglacial to holocene a 14c chronostratigraphy of environmental changes in the konya plain turkey abstract in the endoreic semi arid konya basin on the central anatolian plateaux long term hydrological evolution has left various landforms and lacustrine deposits reflecting the regional climatic evolution as well as human influence on the local environments this paper presents results from a cooperative programme grouping several institutes from turkey and france on lacustrine marshy and aeolian sediment sequences of upper pleistocene and holocene age the detailed study of environmental evolution is based on the reconstruction as well as on the characterization of the extension and contraction phases of wetlands occupying the lowest parts of the konya plain a soil and a marsh layer are 14c dated ca 28 000 25 000 yr bp three phases of pleniglacial from ca 22 000 to 17 000 yr bp high lake levels are distinguished complementary osl dates on aeolian dunes confirm the occurrence of two drought periods the first occurs around the start of the late glacial the second after the mid holocene climatic optimum the latter being in phase with a similar drought in other eastern mediterranean regions after 17 000 yr bp no lacustrine phase reached as high a level as the pleniglacial lake during the late glacial a shallow freshwater lacustrine phase is identified from 12 500 to 11 000 yr bp the late glacial to holocene transition corresponds to a general absence of deposits and dateable material thus suggesting a period of drought to which no aeolian features have so far been related the holocene environmental evolution shows a period of marsh and shallow lake extansion from 6000 to 5500 yr bp this wetter period is interrupted by the second drought ca 5500 yrs bp as indicated by aeolian dune activity during the late holocene a renewal of marshes as well as soil development on slopes can be interpreted either as climatic changes or as impacts of human use of water and soil resources during prehistoric and historic times

contrasting impacts of dansgaard oeschger events over a western european latitudinal transect modulated by orbital parameters abstract terrestrial and marine proxies pollen planktic and benthic foraminiferal oxygen isotopes alkenone and foraminifer derived sea surface temperatures ssts ice rafted debris from images deep sea cores md95 2042 and su81 18 37 n 10 w md99 2331 and md03 2697 42 n 9 w and md04 2845 45 n 5 w show that western european and offshore environments were strongly affected by dansgaard oeschger d o and heinrich h events we concentrate here on latitudinal variability in the forest cover extent and composition of western europe during the succession of d o events showing new pollen records for core md04 2845 and for marine isotopic stages mis 3 and 4 of core md99 2331 in general cold ssts characteristic of greenland stadials were contemporaneous with the expansion of semi desert or steppic vegetation while greenland interstadials were synchronous with the expansion of forest our data reveal that the amplitude of atlantic and mediterranean forest expansions differs for any given d o warming during the glacial period 74 18 ka in the western mediterranean d o 16 17 and d o 8 and 7 corresponding to minima in precession were associated with strong expansion of forest cover contrasting with weak expansion of forest cover during d o 14 and 12 the opposite pattern is revealed at the atlantic sites further north the strongest greenland warmings are recorded for d o 19 11 and 8 this contrasting latitudinal climatic scenario is compared with other northern hemisphere records revealing similarities between the mediterranean climate and the asian monsoon regime which may relate to a summer atmospheric teleconnection between the two regions comparable to the present day situation parallels between mediterranean climate enhancement and peaks in global methane ch 4 during the last glacial period suggest a significant role of monsoon activity in determining ch 4 emission from wetlands

constraints on hydrological and paleotemperature variations in the eastern mediterranean region in the last 140 ka given by the δd values of speleothem fluid inclusions abstract speleothem fluid inclusions potentially provide vital data on the paleohydrological conditions in glacial and interglacial periods we show here that d analyses of fluid inclusions from speleothems in three caves in the eastern mediterranean region israel provide a basis for understanding hydrological and temperature variations in the last 140 ka using measured d fluid inclusion values and temperature ranges constrained by the present day mediterranean meteoric water line mmwl and the global mwl we show a strong compatibility between the land and marine temperature records with the highest land temperatures occurring at 120 130 ka 17 22 c and the present 18 c and the lowest temperatures during the lgm about 10 c lower than present interglacial waters are constrained to follow the mmwl and most glacial waters also plot close to the mmwl with a slight shift towards the mwl however during two remarkable brief periods at the termination of the lgm the waters plot on the mwl suggesting that both sharp cooling and an increase in relative humidity above the em sea reduced d excess values to those of the global system

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

paleoclimate reconstruction based on the timing of speleothem growth and oxygen and carbon isotope composition in a cave located in the rain shadow in israel high resolution th 230 u 234 ages and delta 18 o and delta 13 c compositions of speleothems in ma ale efrayirn cave located to the east of the central mountain ridge of israel enable us to examine the nature of the rain shadow aridity during glacial and interglacial intervals speleothem growth occurred during marine glacial isotopic periods with no growth during the two last marine isotope interglacial intervals and during the peak of the last glacial maximum this contrasts with speleothem growth in caves located on the western flank of the central mountain ridge in the eastern mediterranean semiarid climatic zone which continued throughout the last 240 000 yr thus during glacial periods water reached both sides of the central mountain ridge a comparison of the present day rain and cave water isotopic compositions and amounts at the ma ale efrayim cave site with those on the western flank shows that evaporation and higher temperatures on the eastern flank are major influences on isotopic composition and the lack of rainfall the delta 18 o and delta 13 c profiles of the speleothems deposited between 67 000 and 25 000 yr b p match the general trends of the isotopic profiles of soreq cave speleothems suggesting a similar source eastern mediterranean sea and similar climatic conditions thus during glacial periods the desert boundary effectively migrated further south or east from its present day location on the eastern flank whereas interglacial periods appear to have been similar to the present with the desert boundary at the same position the decrease in overall temperature and a consequent reduction in the evaporation to precipitation ratios on the eastern flank are viewed as the major factors controlling the decay of the rain shadow effect during glacial periods c 2003 elsevier science usa all rights reserved

glacial interglacial temperature variations in soreq cave speleothems as recorded by clumped isotope thermometry clumped isotope thermometry is based on analyzing mass 47 in co2 extracted from carbonates and uses the tracer mass 47 anomaly 47 47 is defined as the deviation of r47 from that expected for a random distribution of isotopologues and reflects a temperature dependent preference of 13c and 18o to create a bond with each other in co2 or in the carbonate lattice being an internal characteristic of the carbonate mineral it is independent of the isotopic composition of the water in which equilibrium precipitation of the carbonate occurs and can therefore be used to independently determine carbonate growth temperatures this work provides a first examination of the applicability of clumped isotopes thermometry to reconstructing the growth temperatures of speleothems by examining the glacial interglacial variations of the 47 values of speleothem carbonates from soreq cave israel the results indicate that the last glacial maximum temperatures were 6 7 c colder than modern day temperature and a sample at 56 ky bp was 3 c colder than the modern early holocene temperatures were slightly above modern day and late holocene temperatures were slightly below modern day these temperature variations are similar to those previously estimated for eastern mediterranean sea surface water cave water was 18o depleted in the holocene compared to modern day by 0 6 1 and 1 1 more enriched in the last glacial maximum comparison of these cave water 18o values with fluid inclusion d values indicated a late holocene d excess value within the range of modern rainfall implying not vert similar45 relative humidity last glacial maximum and early holocene d excess values were significantly lower suggesting relative humidity of not vert similar60 and not vert similar70 respectively the temperatures reported in this study were empirically corrected for a non equilibrium artifact observed in a modern speleothem the similarity of the temperature variations obtained here to other independent records in the region suggests that the 47 temperature calibration slope observed in inorganic synthetic calcite and marine organisms may also be applied in speleothems but the offset observed in modern temperature suggests that the intercept is different so that a separate calibration is needed for accurate absolute temperature reconstruction using speleothem clumped isotopes similar examination of additional caves would be necessary to determine whether such empirical correction can be generally applied or is it a unique characteristic of soreq cave

the role of seasonality in abrupt climate change abstract a case is made that seasonality switches dominated by wintertime were instrumental in abrupt climate changes in the north atlantic region during the last glaciation and into the holocene the primary evidence comes from mismatches between mean annual temperatures from greenland ice cores in comparison with snowline changes in east greenland northern europe and north america the most likely explanation is a shutdown or reduction in strength of the conveyor this allows the spread of winter sea ice across the north atlantic thus causing the northern region to experience much colder winters because they mimic the greenland temperature rather than the snowline signal changes in the atlantic intertropical convergence zone and the asian monsoon may also share a winter linkage with greenland thus the paleoclimate record is consistent with the notion that a huge continental sector of the northern hemisphere stretching from greenland to asia was close to an extreme winter threshold during much of the last glaciation winter climate crossed this threshold repeatedly with marked changes in seasonality that may well have amplified and propagated a signal of abrupt change throughout the hemisphere and into the tropics

a 500 yr speleothem derived reconstruction of late autumn winter precipitation northeast turkey a verified instrumental calibration of annually resolved 18o for a stalagmite from gumushane in northeast turkey is presented and cross validated using a leave one out technique the amount of late autumn to winter precipitation is negatively correlated with stalagmite 18o between ad 1938 and 2004 the observed relationship is extrapolated back to ad 1500 leading to the first long winter precipitation reconstruction for this region modern day october to january precipitation is linked to pressure fields in western russia anomalously lower reconstructed rainfall is recorded in ad 1540 1560 at which time higher pressure over the caspian sea region is inferred

chinese stalagmite δ 18 o controlled by changes in the indian monsoon during a simulated heinrich event carbonate cave deposits in india and china are assumed to record the intensity of monsoon precipitation because the 18 o of the carbonate tracks the isotopic signature of precipitation these records show spatially coherent variability throughout the last ice age and suggest that monsoon strength was altered during the millennial scale climate variations known as dansgaard oeschger events and during the heinrich cooling events here we use a numerical climate model with an embedded oxygen isotope model to assess what caused the shifts in the oxygen isotope signature of precipitation during a climate perturbation designed to mimic a heinrich event our simulations show that a sudden increase in north atlantic sea ice extent during the last glacial period leads to cooling in the northern hemisphere reduced precipitation over the indian basin and weakening of the indian monsoon the precipitation is isotopically heavier over india and the water vapour exported to china is isotopically enriched our model broadly reproduces the enrichment of 18 o over northern india and east asia evident in speleothem records during heinrich events we therefore conclude that changes in the 18 o of cave carbonates associated with heinrich events reflect changes in the intensity of indian rather than east asian monsoon precipitation