direct determination of the timing of sea level change during termination ii an outcrop within the last interglacial terrace on barbados contains corals that grew during the penultimate deglaciation or termination ii we used combined 230th and231pa dating to determine that they grew 135 8 0 8 thousand years ago indicating that sea level was 18 3 meters below present sea level at the time this suggests that sea level had risen to within 20 of its peak last interglacial value by 136 thousand years ago in conflict with milankovitch theory predictions orbital forcing may have played a role in the deglaciation as may have isostatic adjustments due to large ice sheets other corals in the same outcrop grew during oxygen isotope 18o substage 6e indicating that sea level was 38 5 meters below present sea level about 168 0 thousand years ago when compared to the 18o signal in the benthic v19 30 v19 28 record at that time the coral data extend to the previous glacial cycle the conclusion that deep water temperatures were colder during glacial periods

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

reconstruction of lake level changes in lake xinias central greece during the last 40 000 years abstract the investigation of lake xinias greece deals with lake level changes since about 40 000 b p particular effort was made to obtain a reconstruction of lake level during the last glacial maximum at about 18 000 b p the reconstruction was based on a transect of sediment cores the cores were pollen stratigraphically correlated and the interpretation of the sediment stratigraphy was based on sediment chemical and mineral magnetic analyses the chronology was based on accelerator and conventional radiocarbon datings the most striking change was a lake level lowering at about 32 000 b p resulting in an overgrowing of the whole lake the lake level probably remained generally low until somewhat before 15 000 b p the period around the last glacial maximum must have been characterized by a low lake level which is in contrast to the hitherto common opinion additional investigations are required to demonstrate that the lake level changes reconstructed in lake xinias are regionally significant and record climatic changes however it may already be suggested that the conflict between pollen and lake level evidence which hitherto has produced controversy about the glacial climate perhaps does not exist the low lake level in lake xinias around the last glacial maximum is in accordance with the pollen evidence of steppe vegetation both recording a dry climate another distinct lowering occurred around the late wurmian holocene boundary at about 10 000 b p some minor lowerings are recorded also during the holocene e g at about 6000 5000 and 3000 b p

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

age and paleoclimatic significance of late holocene lakes in the carson sink nv usa abstract new dating in the carson sink at the termini of the humboldt and carson rivers in the great basin of the western united states indicates that lakes reached elevations of 1204 and 1198 m between 915 and 652 and between 1519 and 1308 cal yr b p respectively these dates confirm morrison s original interpretation lake lahontan geology of the southern carson desert professional paper 40 u s geol survey 1964 that these shorelines are late holocene features rather than late pleistocene as interpreted by later researchers paleohydrologic modeling suggests that discharge into the carson sink must have been increased by a factor of about four and maintained for decades to account for the 1204 m lake stand the hydrologic effects of diversions of the walker river to the carson sink were probably not sufficient by themselves to account for the late holocene lake level rises the decadal long period of increased runoff represented by the 1204 m lake is also reflected in other lake records and in tree ring records from the western united states

a linkage among pangean tectonism cyclic alluviation climate change and biologic turnover in the late triassic the record from the chinle formation southwestern united states abstract high precision geochronology provides unprecedented insights into the depositional history of the upper triassic chinle formation of the colorado plateau as well as its paleoenvironmental and paleobiological records the chinle succession exposed in the petrified forest national park pefo and vicinity arizona includes two large scale alluvial composite sequences although each composite sequence fines upward the upper composite sequence is more dominated by coarser grained deposits petrographic analysis of sandstone lithic content indicates an upward decrease in the proportion of volcanic rock fragments in each composite sequence paleocurrent indicators in the lower composite sequence suggest a variable paleoflow direction whereas northward paleoflow dominated the upper composite sequence the change in paleoflow appears to coincide with a reorganization of alluvial depositional processes and associated source terranes and precedes a rapid acceleration in basin subsidence climate proxy records from paleosol geochemistry indicate a gradual shift from humid to dry conditions across the transition between the lower and upper composite sequences and the adamanian revueltian biotic turnover composite sequence depositional reorganization climatic shift and biologic turnover in turn appear to coincide with episodes of magmatism recorded in triassic granitoid plutons presently exposed in southern california taken collectively these observations suggest that the late triassic depositional climatic and ecologic history at pefo may be related to emergence of the incipient cordilleran magmatic arc along the convergent western margin of pangea a new u pb date for the lower part of the chinle formation suggests that most or all of the formation was deposited in the norian stage

changes in vegetation and marine environments in the eastern mediterranean rhodes greece during the early and middle pleistocene pollen records marine faunal associations and stable isotope compositions of sediments from rhodes greece have been determined to track environmental changes in the eastern mediterranean during the early and middle pleistocene a detailed chronostratigraphic curve based on magnetostratigraphic data was obtained by correlating pollen spectra with the mediterranean oxygen isotopic curve of ocean drilling program site 975 five sedimentary sequences that correspond to marine oxygen isotope stage mis 31 27 and to mis 20 17 have been investigated in the confined tsampika microbasin high amplitude pinus variations confirm glacio eustatic changes deduced from changes in marine faunal associations and sedimentary depositional environments reflecting climatic cycles identified in the marine carbonate oxygen isotope record eight vegetation successions characterized by the dominance first of mesothermic elements then of mid and high altitude elements with pinus and ending with maxima in herb and steppe elements have been documented most of them were probably driven by changes in insolation occurring in high northern latitudes obliquity impact during the late early pleistocene and early middle pleistocene

comparison of changes in vegetation in northeast greece with records of climate variability on orbital and suborbital frequencies over the last 450 000 years abstract a new direct pollen orbital tuning procedure based on a correspondence between changes in certain vegetation elements and march and june perihelion configurations is applied to the tenaghi philippon record northeast greece the development of a refined chronological scheme allows comparisons to be made with records of climate variability from the north atlantic as well as of global sea level ice volume and atmospheric co2 content on orbital frequencies the comparison reveals a close correspondence between relative ice volume extent and tree population size during glacial intervals during interglacial and interstadial periods the degree of forest development is more closely associated with high latitude insolation and related climate regimes rather than extent of residual ice volume on suborbital frequencies the greek record shows similar repeat times in peaks of steppe vegetation with north atlantic ice rafting events but the amplitude of this variability in the two records is not always proportional overall what emerges is that the major shifts in the relative abundance of forest v open vegetation communities at tenaghi philippon on orbital and suborbital frequencies over the last 450 000 years are coherent with high latitude changes affecting atmospheric and oceanic circulation glacial decreases in atmospheric co2 content contributed to the elimination of tree populations by exacerbating water stress conditions during arid intervals but do not appear to be the primary driver of the observed vegetation changes at this latitude variations in co2 levels in the order of 40 ppmv between different interglacial interstadials periods with adequate moisture availability appear to have had a limited effect on the nature and size of tree populations

four climate cycles of recurring deep and surface water destabilizations on the iberian margin centennial climate variability over the last ice age exhibits clear bipolar behavior high resolution analyses of marine sediment cores from the iberian margin trace a number of associated changes simultaneously proxies of sea surface temperature and water mass distribution as well as relative biomarker content demonstrate that this typical north south coupling was pervasive for the cold phases of climate during the past 420 000 years cold episodes after relatively warm and largely ice free periods occurred when the predominance of deep water formation changed from northern to southern sources these results reinforce the connection between rapid climate changes at mediterranean latitudes and century to millennial variability in northern and southern polar regions

sea level during the penultimate interglacial period based on a submerged stalagmite from argentarola cave italy accurate constraints are presented for the absolute age duration and sea level for the highstand corresponding to marine isotope stage mis 7 1 our work is based on a stalagmite collected in a currently submerged cave from italy argentarola cave flooding of this coastal cave is clearly marked within the stalagmite by a thick marine overgrowth of serpulid worms precise uranium thorium u th ages measured by thermal ionization mass spectrometry suggest that the stalagmite growth varied in phase with climate during mis 7 2 and mis 6 the penultimate glacial period in addition the period of marine transgression is bracketed between 202 and 190 kyr bp defining a mis 7 1 duration of 11 2 kyr comparison with previous studies provides a new constraint on the sea level during mis 7 1 that has approximately remained between 318 and 39 m relative to present sea level the timing of the mis 7 1 highstand is in full agreement with the specmap chronology which contrasts with the growing body of evidence showing a significant phase difference for mis 5 5 a tempting conclusion is that second order sea level highstands such as mis 7 1 may be purely driven by astronomical changes in contrast with major terminations such as termination ii atmospheric co2 levels may partly explain this contrast since the two sea level transitions mis 7 2 7 1 and mis 6 5 5 are characterized by very different co2 rises 20 vs 100 ppm fl 2002 elsevier science b v all rights reserved

a mis 15 mis 12 record of environmental changes and lower palaeolithic occupation from valle giumentina central italy abstract an integrated geological study including sedimentology stable isotope analysis 18o 13c geochemistry micromorphology biomarker analysis 40ar 39ar geochronology and tephrochronology was undertaken on the quaternary infill of the valle giumentina basin in central italy which also includes an outstanding archaeological succession composed of nine human occupation levels ascribed to the lower and middle palaeolithic 40ar 39ar dating and other palaeoenvironmental and tephrochronological data constrain the sedimentary history of the whole succession to the mis 15 mis 12 interval between 618 13 ka and 456 2 ka palaeoenvironmental proxies suggest that over this time interval of about 150 ka sedimentary and pedogenic processes were mainly influenced by climatic changes in particular by the pulsing of local mountain glaciers of the majella massif specifically the valle giumentina succession records glacio fluvial and lacustrine sedimentation during the colder glacial periods and pedogenesis and or alluvial sedimentation during the warmer interglacial and or interstadial periods during this interval tectonics played a negligible role as a driving factor of local morphogenesis and sedimentation whereas the general regional uplift experienced in the middle pleistocene led to capture of the basin and its definitive extinction after mis 12 these data substantially improve previous knowledge of the chronology and sedimentary evolution of the succession providing for the first time a well constrained chronological and palaeoenvironmental framework for the archaeological and human palaeoecological record of valle giumentina

severity and speed of northern hemisphere glaciation pulses the limiting case a brief pulse of ice sheet growth of enormous amplitude predicted by the theory of milankovitch is confirmed by oxygen isotopic and other evidence in pacific and north atlantic cores this glaciation bisected interglacial isotopic stage 7 lasted no more than 23 000 yr from inception to end and resulted in a very large ice volume buildup and a full glacial climatic response of the north atlantic ocean this pulse along with other episodes of rapid and large scale ice growth does not conform to the conventional sawtooth model of slow ice accumulation and rapid ice decay ice growth rates on such pulses can approach the mean ice decay rates on isotopic glacial terminations

high precision mass spectrometric uranium series dating of cave deposits and implications for palaeoclimate studies calcite deposits in caves known as speleothem can provide valuable palaeoenvironmental information1 4 in particular because speleothem are deposited only in air filled caves gaps in deposition in coastal caves record high stands of sea level here we report the use of isotope dilution mass spectrometry to date speleothem by the uranium series method the use of mass spectrometry in uranium series dating was first applied to corals5 and has greatly improved the precision of this dating method the speleothem dated here a flowstone from 15 m below modern sea level in a bahamian cave records changes in sea level over the past 280 000 years the dated hiatuses in deposition indicate high sea level stands that are in general agreement with data from deep sea oxygen isotope stratigraphy6 and other estimates for the timing of high stands and glacial minima1 3 7

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

high resolution climate records from the north atlantic during the last interglacial the two deep ice cores recovered by the grip1 and gisp22 projects at summit greenland agree in detail over the past 100 000 years3 and demonstrate dramatic climate variability in the north atlantic region during the last glacial before the current period of holocene stability this glacial climate instability has subsequently been documented in the marine sedimentary record of surface ocean conditions in the north atlantic4 before 100 kyr ago the two ice core records are discrepant however casting doubt on whether the oxygen isotope fluctuations during the last interglacial eemian seen in the grip core1 5 represent a true climate signal here we present high resolution records of foraminiferal assemblages and ice rafted detritus from two north atlantic cores for the interval 65 kyr to 135 kyr ago extending the surface ocean record back to the eemian the correlation between our records and the greenland ice core records is good throughout the period in which the two ice cores agree suggesting a regionally coherent climate response during the eemian our marine records show a more stable climate than that implied by the grip ice core suggesting that localized phenomena may be responsible for the variability in the latter record during the eemian

a discontinuous climatic record from 187 to 74 ka from a speleothem of the clamouse cave south of france this study presents a continental paleoclimatic record in the south of france based on n 18 o n 13 c and the 234 u 238 u activity ratio dated by the 230 th 234 u disequilibrium method with thermal ionization mass spectrometry a stalagmite cla4 from the clamouse cave offers a discontinuous stable isotopic record between 189 ka and 74 ka which covers marine isotope stages mis 7 6 4 5 5 5 3 and 5 1 the growth phases of the cla4 stalagmite correspond to high sea level stages except during mis 6 4 169 162 ka all the growth phases of cla4 correspond to humid periods corresponding to the sapropel events observed in the eastern mediterranean basin thus the influence of a strong hydrological activity in the eastern mediterranean basin during these periods prevailed as far west as the south of france because the karstic system studied strongly buffers the isotopic composition of water isotopic variations of the calcite deposited in the cave represent mainly global and large scale environmental variations when isotopic equilibrium conditions prevailed for calcite crystallization sub stage 5 3 the end of 5 5 and mis 7 were colder by about 4 6 c calculated temperature compared to present day temperature while the growth phases of substages 5 1 and the beginning of 5 5 reflect environmental conditions close to present ones the n 18 o and n 13 c values of cave deposits of the sub stage 6 4 are 1 strongly marked by kinetic fractionation processes such as evaporation due to moisture deficit within the cave atmosphere during the first step of this growth phase and 2 related to higher humidity due to a second period of enhanced rainfall during the second step of growth this study shows that even if calcite has not been deposited at isotopic equilibrium its isotopic composition can give insights into the environmental conditions at the time of deposition 2002 elsevier science b v all rights reserved

tephrochronology of the central mediterranean mis 11c interglacial 425 395 ka new constraints from the vico volcano and tiber delta central italy abstract through a systematic integrated approach which combined lithostratigraphic geochronological and geochemical analyses of tephra from near source sections of the peri tyrrhenian volcanoes and mid to distal settings here we provide an improved tephrochronological framework for the marine isotope stage 11c interglacial mis 11c 425 395 ka in the central mediterranean area specifically we present the complete geochemical dataset and new high precision 40ar 39ar ages of the previously poorly characterized earliest pyroclastic products of the vico volcano 420 400 ka including the plinian eruptions of vico and vico and the immediately post dating lower magnitude explosive events furthermore we also provide new geochronological and geochemical data for the distal tephra layers preserved in the aggradational succession of the tiber delta san paolo formation roman area which records sea level rise relating to the mis 12 glacial to mis 11 interglacial transition five pyroclastic units were recognized in vico volcanic area four out of which vico vico vico top a minor eruption immediately following vico and temporally very close to it and vico were directly dated at 414 8 2 2 ka 406 5 2 4 ka 406 4 2 0 ka and 399 7 3 2 ka respectively 2 analytical uncertainties these new data allow a critical reappraisal of the previously claimed identifications of vico tephra from mid distal to ultra distal successions i e vico sabatini volcanic districts roman san paolo formation and castel di guido archaeological site sulmona basin valdarno and lake ohrid which were unavoidably biased by the poor and incomplete geochemical and geochronological reference datasets previously available such an improvement of the tephrochronological framework brings great benefits to any future investigations e g paleoclimatology archaeology active tectonic volcanology in the dispersal areas of the studied eruptions at the key point in time that is mis 11

interglacials of the last 800 000 years interglacials including the present holocene period are warm low land ice extent high sea level end members of glacial cycles based on a sea level definition we identify eleven interglacials in the last 800 000 years a result that is robust to alternative definitions data compilations suggest that despite spatial heterogeneity marine isotope stages mis 5e last interglacial and 11c 400 ka ago were globally strong warm while mis 13a 500 ka ago was cool at many locations a step change in strength of interglacials at 450 ka is apparent only in atmospheric co2 and in antarctic and deep ocean temperature the onset of an interglacial glacial termination seems to require a reducing precession parameter increasing northern hemisphere summer insolation but this condition alone is insufficient terminations involve rapid nonlinear reactions of ice volume co2 and temperature to external astronomical forcing the precise timing of events may be modulated by millennial scale climate change that can lead to a contrasting timing of maximum interglacial intensity in each hemisphere a variety of temporal trends is observed such that maxima in the main records are observed either early or late in different interglacials the end of an interglacial glacial inception is a slower process involving a global sequence of changes interglacials have been typically 10 30 ka long the combination of minimal reduction in northern summer insolation over the next few orbital cycles owing to low eccentricity and high atmospheric greenhouse gas concentrations implies that the next glacial inception is many tens of millennia in the future

climate variability in the spanish pyrenees during the last 30 000 yr revealed by the el portalet sequence abstract palynological sedimentological and stable isotopic analyses of carbonates and organic matter performed on the el portalet sequence 1802 m a s l 42 48 00 n 0 23 52 w reflect the paleoclimatic evolution and vegetation history in the central western spanish pyrenees over the last 30 000 yr and provide a high resolution record for the late glacial period our results confirm previous observations that deglaciation occurred earlier in the pyrenees than in northern european and alpine sites and point to a glacial readvance from 22 500 to 18 000 cal yr bp coinciding with the global last glacial maximum the patterns shown by the new high resolution pollen data from this continental sequence chronologically constrained by 13 ams 14c dates seem to correlate with the rapid climate changes recorded in greenland ice cores during the last glacial interglacial transition abrupt events observed in northern latitudes heinrich events 3 to 1 oldest and older dryas stades intra allerod cold period and 8200 cal yr bp event were also identified for the first time in a lacustrine sequence from the central western pyrenees as cold and arid periods the coherent response of the vegetation and the lake system to abrupt climate changes implies an efficient translation of climate variability from the north atlantic to mid latitudes

causes of model data discrepancies in european climate during oxygen isotope stage 3 with insights from the last glacial maximum abstract oxygen isotope stage 3 ois 3 encompassing the long middle section of the last glacial interval has been the focus of an intensive high resolution climate modeling effort for europe these model simulations produce substantially colder climates than modern simulations however the temperatures appear warmer than many proxy indicators suggest in order to evaluate the importance of the model boundary conditions comparable simulations are completed for the last glacial maximum lgm the lgm simulation produces a much colder european continent than ois 3 despite similarities in the specification of sea surface temperatures ssts ice sheet dimension is evidently a key factor in explaining the difference in european climates over the past 40 000 yr however underestimates in specified ois 3 ice sheets cannot be invoked to explain the discrepancies since data strongly indicate small ice sheet extents at that time this leaves errors in specified ois 3 ssts as the most likely cause

orbital signature of interglacials a specific orbital configuration high obliquity combined with the june perihelion marked the beginning of the past three interglacials this suggests that the primary cause of the glacial cycle may be astronomical an astronomical climate index aclin is introduced which combines the three orbital variables in the time lag bivariant model designed to predict the major climate changes in the late and middle pleistocene and in the near future aclin closely correlates with the major climatic events revealed by independently dated proxy climate indicators of the past 130 000 yr it successfully differentiates the interglacials and displays a 100 000 yr periodicity it predicts an early end of the present inter glacial and the start of a new one in 114 000 yr

huge ice age lakes in russia during an early phase of the last ice age weichselian valdaian about 90 000 yr ago an ice sheet formed over the shallow barents and kara seas the ice front advanced on to mainland russia and blocked the north flowing rivers yenissei ob pechora dvina and others that supply most of the freshwater to the arctic ocean the result was that large ice dammed lakes were formed between the ice sheet in the north and the continental water divides to the south here we present reconstructions and calculations of the areas and volumes of these lakes the lake on the west siberian plain was nearly twice as large as the largest lake on earth today the well mapped lake komi in northeast europe and a postulated lake in the white sea basin would also rank before the present day third largest lake the lakes overflowed towards the south and thus the drainage of much of the eurasian continent was reversed the result was a major change in the water balance on the continent decreased freshwater supply to the arctic ocean and increased freshwater flow to the aral caspian black and baltic seas a sudden outburst of the lakes water to the arctic ocean when the ice sheet thinned is postulated copyright 2001 john wiley sons ltd

middle pleistocene glacier behaviour in the mediterranean sedimentological evidence from the pindus mountains greece detailed sedimentological analyses of diamicton sequences in two areas of the pindus mountains greece indicate multiple episodes of glacier advance and retreat during cold stages of the middle pleistocene these glacial sequences represent some of the most southerly in europe and are important archives of regional and global climate change the pindus glaciers were relatively small by world standards and would have been highly responsive to changes in air temperature and precipitation on mount tymphi at least three phases of glacier advance are recorded within deposits assigned to the skamnellian stage mis 12 further north on mount smolikas a thick multiple diamicton sequence records evidence for multiple glacier advances during both the skamnellian stage and the vlasian stage mis 6 these records highlight the dynamic nature of glacier behaviour in the mediterranean mountains during the middle pleistocene and provide new evidence for unstable cold stage climates

duration of last interglacial conditions in northwestern greece a new astronomical calibration method for long pollen records from southern europe is applied to the last interglacial interval of the ioannina sequence northwest greece this shows that the last interglacial in this region as defined by the presence of forest communities lasted c 15 500 years from 127 300 to 111 800 yr b p interglacial conditions developed within marine isotope sub stage mis 5e and persisted into mis 5d lagging changes in global ice volume

synchroneity between marine and terrestrial responses to millennial scale climatic variability during the last glacial period in the mediterranean region land sea climatic proxies have been obtained from the last glacial section of images core md95 2043 western mediterranean sea vegetation and alkenone derived sst curves indicate rapid 150 years and synchronous terrestrial and marine climatic changes paralleling the dansgaard oeschger d o climatic variability over greenland this frequency of climate change can be related to shifts between the two modes of operation of the north atlantic oscillation nao transfer functions applied to the pollen data indicate that there was an amplification of the climatic signal during heinrich events hes in comparison with other d o stadials the development and persistence of both scandinavian and atlantic mobile polar highs over southwestern europe may explain the extreme cooling 10 c and dryness 400 mm during heinrich events 5 and 4 in the mediterranean region comparison of the results of core md95 2043 with similar climatic data from images core md95 2042 located off portugal indicates that thermal and precipitation gradients occurred between the mediterranean and the atlantic sides of iberia within hes hes 4 and 5 are associated with more humid conditions in the atlantic by 200 mm than in the mediterranean site as is the case at the present time this comparison also illustrates the different behaviour of these areas during the d o stadials in contrast with the mediterranean site the atlantic site shows similar precipitation and temperature drops for all the d o stadials including those related to the hes here we propose the operation of different mobile polar highs mph as the driving mechanism for this difference in behaviour between the atlantic and mediterranean sides of iberia hes are related to a stronger influence of the scandinavian mph forcing a severe aridification and cooling of the full iberian peninsula the atlantic mph may have been dominant during the other stadials which would preferentially affect southwestern iberia

long term variations of monthly insolation as related to climatic changes qualitative multivariate models which combine past insolations of selected months at selected latitudes explains 55 to 67 of the variance in the 135 millenia long oxygen isotope record of pleistocene climates

global ice volume fluctuations north atlantic ice rafting events and deep ocean circulation changes between 130 and 70 ka multiproxy data from north atlantic deep sea sediment core neap18k provide a detailed record of climate through oxygen isotope stage ois 5 seven distinct large scale episodes of ice rafting c25 c19 were identified between 126 and 70 ka global ice volume reconstructions based on high resolution benthic 18 o records indicate that major ice rafting events were not confined to ice volume maxima at ois 5d and 5b but also occurred during periods of ice sheet growth and disintegration however iceberg discharges were restricted to times when sea levels were 40 65 m below present values ice rafting episode c25 the first large scale cooling of mid atlantic surface waters after the last interglacial occurred during the gradual buildup of continental ice sheets at the ois 5e 5d transition major ice sheet collapses allied to ice rafting events c24 and c21 were associated with rapid sea level increases of 20 and 40 m respectively suborbital climatic fluctuations in the neap18k sedimentary record denoted by prominent 7 5 4 5 and 3 k y cyclicities appear to correlate with both greenland atmospheric temperatures and changes in thermohaline circulation patterns inferred from benthic 13 c values and hence provide clear evidence of a highly interconnected north atlantic climatic regime during ois 5

relation between low latitude insolation and δ18o change of atmospheric oxygen for the last 200 kyrs as revealed by mediterranean sapropels the isotopic ratio of atmospheric o2 18oatm deduced from ice cores displays large fluctuations during climatic cycles these are caused principally by changes in the oxygen isotopic ratio of sea water 18osw and changes in the biosphere and in the hydrological cycle as both 18oatm and 18osw coincide closely over the last 135 kyr bp it is generally believed that 18oatm is driven mainly by 18osw here we focus on the major discrepancy which arises between those two signals during the prior isotopic glacial stage 6 around 175 kyr bp discrepancy which calls into question the role of changes in 18osw as the driving mechanism for 18oatm we present arguments based on the occurrence and pollen content of mediterranean sapropels for another source of the 18oatm change insolation at low latitudes via hydrosphere biosphere activity

orbital forcing of the marine isotope stage 9 interglacial milankovitch orbital forcing theory has been used to assign time scales to many paleoclimate records however the validity of this theory remains uncertain and independent sea level chronologies used to test its applicability have been restricted largely to the past approximately 135 000 years here we report u series ages for coral reefs formed on henderson island during sea level high stands occurring at approximately 630 000 and approximately 330 000 years ago these data are consistent with the hypothesis that interglacial climates are forced by northern hemisphere summer solar insolation centered at 65 degrees n latitude as predicted by milankovitch theory

new palaeoenvironmental and palaeoclimatic reconstructions for the middle palaeolithic site of cuesta de la bajada teruel eastern spain inferred from the amphibian and squamate reptile assemblages abstract in the eastern iberian peninsula the archaeological site of cuesta de la bajada teruel spain has produced some of the earliest evidence of middle paleolithic stone tool traditions together with evidence of equid and cervid carcasses defleshed by hominins based on the numerical age of 317 240 ka derived from osl esr and aar dating methods for the lower part of the cuesta de la bajada sedimentological sequence level cb3 as well as the biochronological inferences for the small and large mammal associations the site can be attributed to marine isotope stage mis 8 or the end of mis 9 as amphibians and reptiles have precise environmental and climatic requirements and do not differ at species level from the extant herpetofauna of the iberian peninsula they can contribute to the reconstruction of the landscape and climate in this paper the fossil amphibians and squamate reptiles from cuesta de la bajada are studied for the first time the mutual ecogeographic range and habitat weighting methods were applied to the herpetofaunal assemblages to estimate quantitative data for the landscape and climate reconstructions the climate is shown to have been colder and wetter than today in the interior of eastern spain with mean annual temperature up to 2 5 c lower and mean annual precipitation slightly higher than at present the monthly climatic reconstruction shows differences in the distribution of precipitation over the course of the year with more abundant precipitation from late autumn to spring i e from october to may and more or less similar precipitation to today during the summer months july and august this suggests there was stronger rainfall seasonality between winter and summer than currently occurs the paleoenvironmental reconstruction based on the herpetofaunal assemblage depicts a poorly forested 15 20 patchy landscape with a large representation of dry meadows and scrubland habitats together with well evidenced aquatic habitats these reconstructions are consistent with other proxies recovered at cuesta de la bajada pollen small and large mammals as well as other european mis 8 9 paleoclimatic records we can thus correlate levels cb2 and cb3 with the later part of mis 8 265 257 ka or with a humid fluctuation within the mis9b 303 290 ka it is also possible to provide a new description of the environmental and climatic conditions that occurred in inner spain during a cold period of the late middle pleistocene

climate variability in northwest greece during the last interglacial isotopic and palynological data over the period 115 000 to 135 000 years ago from a lacustrine sequence in northwest greece show distinct oscillations during the intervals leading into and out of the full interglacial whereas in between changes were less pronounced but included a brief fluctuation after peak interglacial conditions temperatures decreased and precipitation increased in a series of steps these data suggest that eemian climate variability was similar to that of the holocene both in terms of amplitude and possibly of pacing

middle pleistocene cold stage climates in the mediterranean new evidence from the glacial record abstract a major reduction in summer temperatures during a middle pleistocene glacial cycle caused the most extensive glaciation recorded in the mediterranean region glaciers in the mountains of greece formed during marine isotope stage mis 12 474 000 427 000 years bp under climatic conditions characterised by mean summer temperatures at least 11 c cooler than today and annual precipitation of 2300 mm at the equilibrium line altitude 1741 m a s l this represents the coldest mean summer temperatures recorded in greece during at least the last 430 000 years later pleistocene glaciations mis 6 and 5d 2 were characterised by warmer summer temperatures and higher annual precipitation

comparison of glacial and interglacial conditions between the polar and subpolar north atlantic region over the last five climatic cycles a multiparameter based interpretation of sediment records from the northeast atlantic and the western nordic seas suggests that during the last 500 000 years only in marine isotopes stage mis 11 5e and 1 were there somewhat comparable interglacial boundary conditions in both regions i e strongly reduced occurrence of iceberg rafted debris ird and high carbonate bioproductivity although the northeast atlantic experienced such conditions during all peak interglaciations with the exception of mis 7 planktic foraminiferal 18o from this region would still indicate that significantly colder sea surface temperatures sst prevailed during mis 11 than during mis 9 5e and 1 this assumption is corroborated by a continuous input of ird into the western nordic seas during mis 11 implying a much steeper sst gradient between the polar and subpolar region and an overall reduced thermohaline activity in the polar latitudes the iceberg proxy also reveals that maximum ird discharge always happened during the final phase of glaciation and into early deglaciation terminations as these ird records from the two regions are characterized by a high time coherency it is concluded that short term variability is a persistent feature of the glacial climate system

a chronology of alluvial fan response to late quaternary sea level and climate change crete abstract to better understand how fluvial systems respond to late quaternary climatic forcing osl and u series dating was applied to stratigraphically significant sedimentary units within a small 2 alluvial fan system the sphakia fan in southwest crete the resultant chronology comprising 32 osl and u series ages makes sphakia fan one of the best dated systems in the mediterranean and suggests that cretan fans responded to climate in two ways first during the transitions between marine isotope stage mis 5a 4 and mis 2 1 sphakia fan was characterised by significant entrenchment and distal shift in the zone of deposition it is proposed that the phases of entrenchment were driven by sea level induced base level fall during mis 5a 4 and landscape stabilisation during the onset of the current interglacial mis 2 1 second with the exception of these two entrenchment episodes fan alluviation occurred across the entire last interglacial glacial cycle in all climatic settings i e interglacials interstadials and stadials it is likely that the topographic setting of the catchment supplying sediment to sphakia fan maintained high sediment transfer rates during most climatic settings enabling fan aggradation to occur except during major climatic driven transitions i e major sea level fall and postglacial vegetation development

climatic conditions during marine oxygen isotope stage 6 in the eastern mediterranean region from the isotopic composition of speleothems of soreq cave israel at several times during marine oxygen isotope stage 6 the eastern mediterranean region was influenced by two extreme climatic systems the large ice sheet over northern europe and the wet tropics associated with african monsoons during this interval two major climatic events occurred in the region the sapropel s6 layer formed ca 176 ka in the eastern mediterranean basin owing to the increase in the african monsoon and another event although not large enough to form sapropel occurred ca 151 ka the isotopic composition of soreq cave speleothems seems to record these events as very low 18 o 13 c values dated as ca 178 and 152 ka the very low 18 o 13 c values of 6 and 11 to 12 respectively are typical of interglacial intervals but here they were recorded during a glacial interval such low peaks indicate that in this part of the eastern mediterranean region i e israel the rainfall amount increased dramatically moreover the isotopic record of the speleothems also shows that during the entire stage 6 although the climate was as cold as much of the last glacial the conditions were never as dry

orbital signatures and long term vegetation patterns in the mediterranean abstract an attempt is made to explore the relation between vegetation phases and orbital configurations by comparing long pollen sequences from the mediterranean region and astronomical curves on the basis of their independent chronologies three recurring patterns emerge from this comparison i all intervals with perihelion passage occurring during northern winter were associated with significant contractions of tree populations ii all temperate stage expansions of certain mediterranean vegetation elements occurred when perihelion passage was in summer and iii temperate stage forests reached maximum extent at times of autumn perihelion of these patterns the first corresponds to extreme dry cold episodes culminating at times of march perihelion and the second to maximum summer temperature and evaporation regimes following june perihelion the third associated with the occurrence of september perihelion appears to be more diffuse both in time and space possibly reflecting local variations in hydrological regimes the consistency of at least the first two cases provides some support for the notion that certain recurring vegetation patterns appear to be a result of climate changes linked to specific orbital signatures this could eventually lead to the development of improved terrestrial chronologies through astronomical tuning

combined marine proxy and pollen analyses reveal rapid iberian vegetation response to north atlantic millennial scale climate oscillations abstract a deep sea sediment core from the western portuguese margin has provided a continuous high resolution record of millennial scale climatic oscillations during the interval 9000 65 000 yr b p pollen analysis of the same sequence allows direct in situ assessment of the phase relationship between the north atlantic climate system and vegetation changes on the adjacent landmass this demonstrates for the first time that variability in nw iberian tree population size closely tracked millennial scale climate variability

rock varnish microlamination dating of late quaternary geomorphic features in the drylands of western usa abstract varnish microlamination vml dating is a correlative age determination technique that can be used to date and correlate various geomorphic features in deserts in this study we establish a generalized late quaternary i e 0 300 ka varnish layering sequence for the drylands of western usa and tentatively correlate it with the specmap oxygen isotope record we then use this climatically correlated varnish layering sequence as a correlative dating tool to determine surface exposure ages for late quaternary geomorphic features in the study region vml dating of alluvial fan deposits in death valley of eastern california indicates that during the mid to late pleistocene 5 15 ky long aggradation events occurred during either wet or dry climatic periods and that major climate shifts between glacial and interglacial conditions may be the pacemaker for alteration of major episodes of fan aggradation during the holocene interglacial time however 0 5 1 ky long brief episodes of fan deposition may be linked to short periods of relatively wet climate vml dating of alluvial desert pavements in death valley and the mojave desert reveals that pavements can be developed rapidly

hydrological conditions over the western mediterranean basin during the deposition of the cold sapropel 6 ca 175 kyr bp a new oxygen isotope record is reported from a stalagmite collected in the argentarola cave located on the tyrrhenian coast of italy as shown from observations and numerical modeling of n 18 o in modern precipitation the recorded n 18 o variability for this zone is dominated by the amount of precipitation so called amount effect the n 18 o profile measured in the stalagmite is characterized by a prominent negative excursion ca 2 3x between 180 and 170 kyr bp this paleoclimatic feature is interpreted as being due to a relatively wet period which occurred during the penultimate glacial period more precisely during marine isotope stage 6 5 this pluvial phase is shown to correspond chronologically to the deposition of the sapropel event 6 s6 although this particular sapropel event occurred during a cold phase the n 18 o excursion is similar to those corresponding to other sapropels s4 s3 and s2 the evidence for humid conditions during s6 in the western mediterranean basin agrees with previous studies based on deep sea sediment cores taken collectively the data suggest that during sapropel events dilution of ocean surface waters was not restricted to the output of the river nile but was rather widespread over the entire mediterranean sea due to increased rainfall 2002 elsevier science b v all rights reserved

geoarchaeological approaches to the environmental history of cyprus explication and critical evaluation geoarchaeology represents crossdisciplinary research focused on environmental issues and human activities and directed primarily to social scientists site micro studies are central to the enterprise emphasizing cultural sediments and the taphonomic record of site formation preservation or destruction but when expanded to include off site investigation and watershed studies geoarchaeology can go well beyond stratigraphy and context to address human impacts on the environment or long term sustainability this paper articulates a research agenda to evaluate the largely anecdotal premise that the island of cyprus has been degraded by millennia of improvident land use first it outlines holocene settlement land use and forest histories as a differentiated model against which to apply specific types of investigation and in conjunction with other archaeological sciences second it applies quaternary style watershed study to confront commonplace misunderstandings about possible degradation to show that most of the slope and stream deposits on cyprus are of pleistocene age third it switches to examples of site micro geoarchaeology to illustrate the possibilities of understanding detailed change the purpose is heuristic in the absence of many more site and off site studies that incorporate bioarchaeology provisional inferences suggest that environmental damage may be limited that even with heavy land use stress climatic triggers were critical to inaugurate change and that the system may be more resilient than anticipated such caveats may encourage greater attention to environmental research design in ongoing and future excavation projects

new insights into the glacial latitudinal temperature gradients in the north atlantic results from uk 37 sea surface temperatures and terrigenous inputs abstract sea surface temperatures sst and input of continental materials have been reconstructed from the study of the long chain alkenones and n alkanes respectively in a core located in the western side of the mid atlantic ridge md952037 37 05 n 32 02 w 2630 m depth both the long and short term variability recorded by the temperatures and the planktonic 18o are basically the same over the last 280 kyr showing a clear glacial interglacial evolution comparison with core su90 08 located only 6 north and directly influenced by the cold polar waters associated with the polar front during glacial times revealed different climatic conditions during glacial periods at both locations whereas core md952037 recorded similar sst values during the last two glacial periods ca 14 15 c the northern core displayed colder conditions during isotopic stage 2 8 10 c than in stage 6 13 15 c these results indicate the existence of a well developed steep north south gradient between 37 and 43 n during the last glacial period but not during stage 6 which suggests a southern expansion of the polar front during the last glacial maximum

interglacial variability mis 5 and mis 7 and dinoflagellate cyst assemblages in the bay of biscay north atlantic the interglacial periods of the late quaternary are frequently investigated as they constitute potential analogues for our modem climate and may shed light on the key questions of natural climate variability and future developments the aim of this work is to reconstruct the paleoenvironmental history of marine isotope stages mis 5 and 7 in deep sea sediments of the northern bay of biscay north east atlantic ocean on the basis of a multiproxy compilation including analysis of dinoflagellate cyst assemblages we discuss the nature of the paleoenvironmental and paleoclimate changes that took place in this region recurrent successions of species marking the beginning and the termination of the interglacial complexes mis 5 and mis 7 revealed a coherent scheme of water mass migration during these key transitional periods moreover our data extend knowledge about the ecology of several dinoflagellate taxa in particular we discuss the ecology of spiniferites septentrionalis and note that this species can be used as a biostratigraphical tracer in north atlantic quaternary sediments until a major event of iceberg calving occurred during mis 6 dated to around 150 ka bp the dinocyst spinferites mirabilis appears to be an important proxy for recognizing warm intervals within interglacial complexes during mis 5e the last interglacial this species is represented by the highest percentages ever recorded in sediments from the north atlantic region peak occurrence of this species during mis 7 indicates that substage mis 7c the second warm interval of the penultimate interglacial represents the climatic optimum during the mis 7 interglacial complex

physiological significance of low atmospheric co2 for plant climate interactions abstract methods of palaeoclimate reconstruction from pollen are built upon the assumption that plant climate interactions remain the same through time or that these interactions are independent of changes in atmospheric co 2 the latter may be problematic because air trapped in polar ice caps indicates that atmospheric co 2 has fluctuated significantly over at least the past 400 000 yr and likely the last 1 6 million yr three other points indicate potential biases for vegetation based climate proxies first c 3 plant physiological research shows that the processes that determine growth optima in plants photosynthesis mitochondrial respiration photorespiration are all highly co 2 dependent and thus were likely affected by the lower co 2 levels of the last glacial maximum second the ratio of carbon assimilation per unit transpiration called water use efficiency is sensitive to changes in atmospheric co 2 through effects on stomatal conductance and may have altered c 3 plant responses to drought third leaf gas exchange experiments indicate that the response of plants to carbon depleting environmental stresses are strengthened under low co 2 relative to today this paper reviews the scope of research addressing the consequences of low atmospheric co 2 for plant and ecosystem processes and highlights why consideration of the physiological effects of low atmospheric co 2 on plant function is recommended for any future refinements to pollen based palaeoclimatic reconstructions

the timing of high sea levels over the past 200 000 years the 230 th ages and 234 u 238 u ratios were determined for barbados corals that grew during periods of high sea level within the last 200 000 years the similarity of the initial 234 u 238 u ratios of some of the corals to the modern marine value suggests that these samples are pristine and that the marine 234 u 238 u ratio 83 000 and 200 000 years ago was within 2 per mil of the modern value the accuracies of the 230 th ages are evaluated on the basis of the 234 u 238 u values and a model of the behavior of uranium and thorium isotopes during diagenesis for the last three interglacial and two intervening interstadial periods sea level peaked at or after peaks in summer insolation in the northern hemisphere this overall pattern supports the idea that glacial interglacial cycles are caused by changes in earth9s orbital geometry the sea level drop at the end of the penultimate interglacial the last interglacial and a subsequent interstadial period lagged behind the decrease in insolation by 5 000 to 10 000 years

paleoenvironmental and climatostratigraphic insights for marine isotope stage 19 pleistocene at the montalbano jonico succession south italy abstract quantitative analyses on pollen and ostracods were performed on the montalbano jonico succession mjs through marine isotope stages mis 18 21 in order to acquire details of paleoenvironmental changes and climate pattern during mis 19 which includes the matuyama brunhes paleomagnetic boundary mbb while the mjs does not record the mbb which is the main criterion for defining the early middle pleistocene boundary it is a candidate global boundary stratotype section and point gssp for the ionian stage and middle pleistocene subseries because of its excellent exposure continuous deposition and astronomically tuned record between mis 37 and mis 16 the new 40ar 39ar age of 773 9 1 3 ka for volcaniclastic layer v4 allows the age model for the succession to be refined ostracod assemblages show significant paleodepth fluctuations at the glacial interglacial scale in agreement with the pollen distality index pinus vs caryophyllaceae amaranthaceae and ephedra which also suggests higher values during mis 19 pollen analysis provides supplementary paleoclimate data that are valuable to reconstruct temperature variation during the identified phases a major expansion of steppic vegetation at 790 ka in the uppermost mis 20 correlates with a significant cold and arid northern hemisphere climate phase as documented by a concurrent peak both in north atlantic ice rafted debris and mediterranean dust records climate conditions recorded in mis 19 3 were similar to those of the present interglacial whereas a dry climate phase marks mis 19 2 at 771 84 ka slightly above the v4 layer millennial scale climate variability occurred during mis 19 as evidenced by two abrupt short term moderately dry pollen events at 783 5 ka and 774 8 ka that could be related to a period of reduced geomagnetic field intensity through the mbb transition additional environmental chronological events accompanied this stratigraphic interval i the volcaniclastic layers v3 and v4 radiometrically dated at 801 2 19 5 ka and 773 9 1 3 ka respectively ii the co occurrence of maximum flooding and thermal maximum in agreement with the previously recorded co occurrence of the neopycnodonte community and tropical subtropical mesopelagic teleostean bonapartia pedaliota close to the increase of quercus and iii the maximum depth md between 777 3 and 773 25 ka as recorded by outer shelf upper slope macroinvertebrate fauna close to the highest value of pollen distality index in mis 19 results enhance the understanding of orbital suborbital paleoenvironmental change during the mid pleistocene and particularly of the climate pattern during mis 19 and across the mbb

linking onshore offshore sediment dispersal in the golo source to sink system corsica france during the late quaternary abstract spatial and temporal relationships between climate tectonics and sea level have a primary control on sediment transport storage and deposition in onshore and offshore depositional environments although many simplistic models have tried to predict onshore system behavior and sediment partitioning between onshore and offshore depositional environments in response to changes in these boundary conditions the alluvial response to changes in external forcings coupled with autogenic processes can be highly complex and unpredictable the golo source to sink system on the eastern margin of the island of corsica in the mediterranean sea provides an ideal laboratory to study sediment partitioning in both onshore and offshore realms the terrestrial part of the system consists of the golo river which debouches onto a narrow shelf 10 km which in turn passes into a narrow 45 km confined basin known as the corsica trough dominated by submarine fan deposits estimates on timing of late quaternary fluvial aggradation are compared with timing of sediment storage on the shelf and on the basin floor fan the results indicate that onshore deposition and storage of sediment in the fluvial system may occur both during sea level highstand transgression and lowstand volume calculations from the alluvial record show that onshore storage is relatively low 13 relative to the overall sediment budget comparing estimated deposition rates with a sediment prediction model further suggests that deep sea fan sedimentation rates at times may be up to 50 higher or 25 lower than what is being supplied by the river indicating temporary storage and release of sediment on the shelf on average however there is good agreement between predicted and calculated sediment volumes in the golo system the study demonstrates the value of investigating the entire source to sink system in order to obtain a comprehensive understanding of sediment dispersal between onshore and offshore depositional environments over 104 year timescales observations suggest that alternating periods of aggradation and degradation of the golo river are controlled by system thresholds controlled from within the catchment comparison with climate proxy data and timing of major alluviation events elsewhere in the mediterranean region supports the notion that each source to sink system has a unique threshold that must be exceeded to induce regional aggradation and subsequent terrace formation the same is also inferred for timing of sediment dispersal to the deep sea environment in addition preservation of onshore sediment is controlled by local factors such as uplift rate and its impact on the aggradational response it is therefore expected that the onshore record may be diachronous on local regional and global scales making detailed correlation difficult except for the most extreme events finally stream incision rates appear to be one to two orders of magnitude higher than regional hinterland denudation rates indicating that the golo system is characterized by increasing landscape relief

the high sensitivity of the palynological record in the vico maar lacustrine sequence latium italy highlights the climatic gradient through europe for the last 90 ka the palynological study of the vice maar lacustrine sequence italy is realized from the correlation of three drillholes the time span covers a period from the end of oxygen isotope substage 5b till the beginning of stage 1 from ca 90 to ca 10 ka bp at the base of the pollen diagram pollen zone 0 a younger dryas like fluctuation is observed after pollen zone 1 which is a well developed forest period substage 5a the forests of pollen zones 3 and 5 correspond to extensive climate improvements these last two zones are correlated to the ognon complex of the grande pile france and to interstadial periods 20 and 19 defined in the grip ice core greenland 72 6 66 2 ka before the stage 5 4 transition these two interstadial periods are global events found in the greenland and antarctica ice sheets as well as in north atlantic marine cores in other pollen records from north of the alps changes have been recorded but they are less pronounced than in vico pollen zone 7 stage 3 shows ca 7 warm humid fluctuations that might have a link to the dansgaard oeschger events greenland during zone 9 the lateglacial interstadial is recorded as well as the younger dryas event the localization of vice near plant refugia and far from the ice cap enables its pollen diagram to record abrupt and intense response to climate changes possibly through a link to the atlantic ocean via westerly winds c 1996 elsevier science ltd

vegetation and climate changes in the south eastern mediterranean during the last glacial interglacial cycle 86 ka new marine pollen record the eastern mediterranean located at the meeting between the mediterranean vegetation of the eurasian continent and the desert vegetation of the saharan arabian desert belt is ideal for tracking changes in regional vegetation as function of climate changes reconstruction of these changes in the south eastern mediterranean during the last 86 ka is based on a palynological record from deep sea core 9509 taken by r v marion dufresne off the southern israeli coast the chronological framework is based on the correlation of d 18 o records of planktonic foraminifera with the high resolution well dated u th speleothem record from the soreq cave israel and the occurrence of sapropel layers several cycles of humid dry periods were documented during the last 86 ka the record starts with the moderate humid and warm sapropel s3 marking the end of marine isotope stage mis 5 the climate during the last glacial period 75 5e16 2 ka was cold and dry with low arboreal pollen ap levels and high values of semi desert and desert vegetation e g artemisia sagebrush the driest and coldest period during the last 86 ka corresponds to mis 2 27 1e16 2 ka characterized by the lowest tree cover along the sequence and the dominance of steppe vegetation some slightly more humid fluctuations were identified during the period of 56 3 and 43 5 ka with its peak between 56 0 and 54 4 ka the most pronounced climate change started at the beginning of the deglaciation 16 2e10 ka and continued throughout the holocene last 10 ka notwithstanding some short fluctuations high ap levels were dominated by quercus callipprinos evergreen oak suggesting that the mediterranean forest was more extensive in the area and the climate was wet sapropels s3 and s1 were clearly recognized here by the high concentrations and good state of preservation of pollen because of the development of anoxia in the bottom water that may be related to more extensive nile discharge coinciding with high insolation values at 65

millennial scale oceanic climate variability off the western iberian margin during the last two glacial periods high resolution palaeoclimate records recovered from the iberian margin in core md95 2040 exhibit large fluctuations in oceanographic conditions over the last 190 ka large scale cooling of the surface ocean is indicated by the presence of the polar planktonic foraminifer neogloboquadrina pachyderma sinistral and in some instances the occurrence of ice rafted debris ird ice rafting episodes were prevalent in both of the last two glacials with greater intensity in stages 2 through 4 than in stage 6 the six youngest heinrich events are well defined during the last glacial but detrital carbonate is absent from heinrich layers hl6 hl5 and hl3 dansgaard oeschger stadial equivalent sub millennial ird deposition events have been detected in particular during stage 3 allowing a good match with the cooling displayed in the greenland ice core gisp2 sea surface temperature off portugal in stage 6 was in general warmer than during the last glacial pointing towards a weaker southward influence of polar water masses ice rafting occurred mainly in mid mis marine isotope stage 6 between 173 and 153 kyr as a group of poorly differentiated short duration quasi continuous events mainly marked by the high abundance of sinistral n pachyderma differences exist in ird composition relative to the last glacial with a reduced canadian derived detrital carbonate component combined with an important contribution of volcanic particles the lower magnitude and higher frequency of these events suggest that the higher temperatures would have induced iceberg waning closer to the source areas

application of a degree day model to reconstruct pleistocene glacial climates there is empirical evidence of a nonlinear relation between annual precipitation or accumulation and summer mean temperature at the equilibrium line altitude ela on glaciers around the world the degree day model gives a similar relation between accumulation and summer temperature although instead of a single universal curve there is a family of curves depending upon the annual temperature range furthermore the degree day model also gives nonlinear relations between accumulation and annual mean temperature thus estimations of accumulation can be made from both summer and annual temperatures at the ela of former reconstructed glaciers such as those in greece this is particularly useful since these climatic variables have major implications for biological proxies such as vegetation history indicated in the pollen record and for periglacial proxies such as permafrost distributions indicated in the geomorphological record the close relationship between glaciers and climate provides one of the most precise methods for reconstructing former climates and offers considerable potential for resolving our understanding of pleistocene cold stage climates

sea level and deep water temperature changes derived from benthic foraminifera isotopic records we show that robust regressions can be established between relative sea level rsl data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle we then apply these regressions to long benthic isotopic records retrieved at one north atlantic and one equatorial pacific site to build a composite rsl curve as well as the associated confidence interval over the last four climatic cycles our proposed reconstruction of rsl is in good agreement with the sparse rsl data available prior to the last climatic cycle we compute bottom water temperature changes at the two sites and at one southern indian ocean site taking into account potential variations in north atlantic local deep water 18o our results indicate that a last glacial maximum lgm enrichment of the ocean mean oxygen isotopic ratio of 0 95 is the lowest value compatible with unfrozen deep waters in the southern indian ocean if local deep water 18o did not increase during glacials with respect to present such a value of the lgm mean ocean isotopic enrichment would impose a maximum decrease in local bottom water 18o at the north atlantic site of 0 30 during glacials

a contribution towards the palynostratigraphical classification of the middle pleistocene in central europe the pollen record of the neualbenreuth maar northeastern bavaria germany abstract palaeoecological evidence of intra saalian warm stages in central europe which was strongly affected by glacial and periglacial processes during the major middle and late pleistocene cold periods is ambiguous so far recently the first continuous sedimentary sequence of central europe containing the saalian complex mis 8 6 with the eemian interglacial in stratigraphic superposition was recovered from the newly discovered neualbenreuth maar ne bavaria here we present palynological results from this record allowing us to critically discuss the available biostratigraphical evidence of alternating intra saalian warm cold intervals from central europe the new pollen record from the neualbenreuth maar comprises a continuous record of vegetation and climate changes encompassing four warm stages and five cold periods the dominance of cold and dry tolerant herbs and the sparse representation of pioneer trees and shrubs during most parts of the sequence indicate open landscapes of steppe to woody steppe character typical of late middle and late pleistocene glacial periods in central europe the pollen assemblages of the warm stage in the upper part of the core clearly support its correlation with the eemian interglacial the three pre eemian warm stages represent terrestrial analogues of the marine isotope stages mis 7e 7c and 7a during each of these intervals forests were established but the reduced abundances and lower diversity of thermophilous and sub oceanic elements in comparison to the eemian attest to a weak interglacial character each of these interglacials shows a similar vegetation succession and only minor differences in the vegetation composition the intervening stadial periods represent a strong mis 7d and a moderate mis 7b climate deterioration respectively the vegetation and climate succession during the saalian glacial interglacial complex of neualbenreuth is broadly in line with the respective palynological signature from the velay record french massif central and the hoogeveen interstadial the netherlands in contrast there is only limited correspondence with most pollen records from northern and southern central europe which were hitherto classified as mis 7

european climatic response to millennial scale changes in the atmosphere ocean system during the last glacial period abstract pollen foraminifer dinocyst and coarse lithic high resolution analyses and 18 o measurements have been carried out for the last glacial section of marine core md95 2042 located near the southwestern margin of the iberian peninsula the pollen data indicate a high frequency of vegetational changes on the adjacent continent during this period suggesting a climatic variability very similar to that of the dansgaard oeschger cycles recorded by the greenland ice cores the detailed direct correlation of the terrestrial and marine proxy data from core md95 2042 indicates a three phase pattern of heinrich events in land and ocean environments the first and last phases of the h5 and h4 events are characterized by a mild and humid climate in southwestern europe probably associated with the european origin of the ice rafted detritus the middle phase exhibits a cold and dry climate in iberia linked with the maximum input of ice rafted detritus this phase seems to correspond with the laurentide ice sheet surges between the heinrich events several cold and dry periods on land are correlated with stades of the dansgaard oeschger cycles the impact of the dansgaard oeschger stades in southwestern europe seems to be preferentially connected to the cold winter air masses reaching this mid latitude region

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr