tentative correlation of pollen records of the last interglacial at grande pile and ribains with marine isotope stages eemian lake deposits in grande pile and ribains france correlate with marine isotope substages mis 5e and 5d as delimited in two pollen bearing deep sea cores off portugal the eemian forests in france lasted for approximately 20 millennia from at least 126 000 to ca 107 000 yr b p oscillatory climate deteriorations began about 115 000 yr ago an intense cold spell affected the region approximately 110 000 yr ago

biogenic silica record of the lake baikal response to climatic forcing during the brunhes abstract this work presents a detailed orbitally tuned biogenic silica record of continental paleoclimate change during the brunhes chron the brunhes matuyama boundary lies within the warm isotopic stage 19 in baikal and the boundaries between eight lithological cycles correspond to terminations in the marine oxygen isotope record the high amplitude and resolution of climatically driven changes in biosi content in lake baikal sediments permits tuning of almost every precessional cycle during the brunhes and reveals the structure of interglacial stages for example the last three interglacial stages mis 5 7 and 9 clearly consist of five substages a b c d e corresponding to precessional insolation peaks abrupt and intense regional glaciations in siberia during substages 5d and 7d were driven by extreme insolation minima during substage 9d cooling was more gradual in response to more moderate forcing the impact of strong glaciation is also observed in the middle of stage 15 where full glacial conditions appear to have lasted for over 30 000 yr during substages 15d 15c and 15b marine oxygen isotopic stage 11 appears to be the warmest period during the brunhes in the lake baikal record with at least three substages a new hypothesis is presented regarding the response of the lake baikal biosi record to insolation forcing based on the mechanism controlling modern diatom blooms biogenic silica production is hypothesized to be dependent on changes in the heat balance of the lake and consequently on changes in the thermal structure of the water column this mechanism is also sensitive to short term sub milankovich cooling events such as the mid eemian cooling the montaigu event during substage 5c and a cooling which appears to be analogous to the montaigu event during substage 9c the continuity of the lake baikal paleoclimate record its sensitivity to orbital forcing and its high resolution make it an excellent candidate for a new paleoclimatic stratotype section for continental asia

open system coral ages reveal persistent suborbital sea level cycles sea level is a sensitive index of global climate that has been linked to earth s orbital variations with a minimum periodicity of about 21 000 years although there is ample evidence for climate oscillations that are too frequent to be explained by orbital forcing suborbital frequency sea level change has been difficult to resolve primarily because of problems with uranium thorium coral dating here we use a new approach that corrects coral ages for the frequently observed open system behavior of uranium series nuclides substantially improving the resolution of sea level reconstruction this curve reveals persistent sea level oscillations that are too frequent to be explained exclusively by orbital forcing

high resolution record of climate stability in france during the last interglacial period the last interglacial period 127 110 kyr ago has been considered to be an analogue to the present interglacial period the holocene which may help us to understand present climate evolution but whereas holocene climate has been essentially stable in europe variability in climate during the last interglacial period has remained unresolved because climate reconstructions from ice cores1 2 continental records3 4 and marine sediment cores5 6 give conflicting results for this period7 here we present a high resolution multi proxy lacustrine record of climate change during the last interglacial period based on oxygen isotopes in diatom silica diatom assemblages and pollen climate transfer functions from the ribains maar in france contrary to a previous study8 our data do not show a cold event interrupting the warm interglacial climate instead we find an early temperature maximum with a transition to a colder climate about halfway through the sequence the end of the interglacial period is clearly marked by an abrupt change in all proxy records our study confirms that in southwestern europe the last interglacial period was a time of climatic stability and is therefore still likely to represent a useful analogue for the present climate

two step deglaciation at the oxygen isotope stage 6 5e transition the zeifen kattegat climate oscillation comparison of marine lacustrine and terrestrial records from twenty four sites suggests the existence of a younger dryas type climate oscillation just prior to the oxygen isotope stage 6 5e boundary these records include results from biostratigraphic pedostratigraphic and speleothem studies as well as analyses of stable isotope compositions of marine records and ice cores the climate oscillation is named after the warm zeifen interstadial and the cold kattegat stadial the zeifen interstadial may be related to a major meltwater pulse in the baffin bay labrador sea norwegian sea region the climate oscillation is presumably in part a result of a variation in ocean circulation especially in the strength of the north atlantic drift but changes in the atmospheric circulation also played an important role the geographically widespread distribution of the oscillation suggests that the two step deglaciation influenced both the northern and southern hemispheres c 1996 elsevier science ltd

last interglacial climates the last interglacial commonly understood as an interval with climate as warm or warmer than today is represented by marine isotope stage mis 5e which is a proxy record of low global ice volume and high sea level it is arbitrarily dated to begin at approximately 130 000 yr b p and end at 116 000 yr b p with the onset of the early glacial unit mis 5d the age of the stage is determined by correlation to uranium thorium dates of raised coral reefs the most detailed proxy record of interglacial climate is found in the vostok ice core where the temperature reached current levels 132 000 yr ago and continued rising for another two millennia approximately 127 000 yr ago the eemian mixed forests were established in europe they developed through a characteristic succession of tree species probably surviving well into the early glacial stage in southern parts of europe after ca 115 000 yr ago open vegetation replaced forests in northwestern europe and the proportion of conifers increased significantly farther south air temperature at vostok dropped sharply pulses of cold water affected the northern north atlantic already in late mis 5e but the central north atlantic remained warm throughout most of mis 5d model results show that the sea surface in the eastern tropical pacific warmed when the ice grew and sea level dropped the essentially interglacial conditions in southwestern europe remained unaffected by ice buildup until late mis 5d when the forests disappeared abruptly and cold water invaded the central north atlantic ca 107 000 yr ago

stalagmite evidence for the onset of the last interglacial in southern europe at 129 1 ka multi proxy data from an italian stalagmite constrain the commencement of full last interglacial conditions in southern europe at 129 1 ka consistent with absolutely dated records currently available from both hemispheres the post glacial transition towards warmer and wetter conditions commenced at 134 2 ka oxygen isotope evidence suggests this was interrupted briefly at 130 2 ka an event probably related to the termination ii pause associated with heinrich event 11 for most of the stalagmite the pattern of delta 18 o variation mimics the air temperature record from the vostok ice core especially through marine isotope stage 5 there is no obvious evidence for substantial early interglacial warming

age and climate of the late saalian and early eemian in the type area amsterdam basin the netherlands abstract lake deposits of late saalian mis 6 and early eemian mis 5e age in glacially excavated basins in the central part of the netherlands provide a high resolution stable isotope and pollen record of the glacial interglacial transition late saalian warm conditions were interrupted by a cold dry interval at the saalian eemian boundary which we correlate to the kattegat stadial and heinrich event 11 this cold interval ties our continental climate record to that of the marine oxygen isotope based time scale oxygen isotope data from this sequence indicate that the subsequent early eemian saw a quick recovery to warm interglacial climatic conditions which was reached already during the pioneer phase of the vegetation the sea transgressed the lake 1 kyr after the start of the eemian and highstand was reached 2 kyr later precipitation increased just prior to transgression of the sea into the lake causing important changes in the vegetation transgression of the isostatically rebounding area once covered by the baltic ice sheet is of early eemian age and becomes younger from the former centre of the ice sheet along the baltic sea to its margin in the netherlands the highstand cannot precede the start of the eemian as the area was emerging assuming that the effect of the isostatic rebound is small along the margin of the former ice sheet and by using the australian u th ages of the eemian highstand coral reefs combined with the duration of the eemian pollen zones derived from the annually layered lake deposits of bispingen it is concluded that the eemian in the netherlands starts at 131 ka

quantitative and qualitative relationships between planktonic diatom communities and diatom assemblages in sedimenting material and surface sediments in lake baikal siberia endemic planktonic diatoms are a major component of lake baikal sediments during interglacial periods to investigate how these diatom assemblages are altered during sediment formation quantitative plankton monitoring 1995 1998 was integrated with sediment trapping over 2 yr 1996 1997 in baikal s southern basin depth 1 400 m the traps consisted of both open 6 monthly and sequential 2 weekly collectors deployed throughout the water column sedimentation was seasonal with diatom species composition valve abundance and total dry mass reflecting changes in the planktonic communities sedimented assemblages were transmitted largely intact to the deepest traps 1 300 1 390 m some compositional blurring occurred from differential sinking rates and dissolution of diatom valves a rapid mass flux event of aulacoseira skvortzowii and a baicalensis was recorded in summer 1997 with particle sinking rates between 60 and 100 m d 21 and dry mass fluxes 5gm 22 d 21 although dissolution was evident for all species more delicate taxa were preferentially affected e g a skvortzowii vegetative cells and finesynedra species whereas nitzschia acicularis valves were almost entirely dissolved within the water column comparing trap and plankton diatom assemblages with those in nearby core tops demonstrated that a fundamental taphonomic change occurs in the surface sediment with sedimentary diatom accumulation rates being only about 1 of trap deposition and plankton production rates dissolution was significant in explaining 5 30 of species variance between all taphonomic levels plankton trap samples and surface sediments results indicate that diatom based paleoclimatic records in lake baikal sediments could be improved and refined by taking taphonomic considerations into account

the eemian interglaciation in northwestern germany abstract hundreds of small lakes became filled with eemian deposits following the retreat of saalian ice in northwestern germany weakly expressed climate oscillations have been inferred from some local pollen records of late saalian sediments sea level stood 7 m below the current northwest german sea level datum nn during the interglacial climate optimum and decreased afterward a uniform vegetational succession of the eemian mixed forests correlated with marine isotope stage mis 5e terminated with the demise of boreal woodlands marked by a steep increase in nonarboreal pollen this is the onset of the early weichselian herning stade correlated with mis 5d no sharp climate oscillations during the eemian have been documented in the ending phase of the interglaciation the climate deteriorated gradually dominant heath and grass tundras point to a substantial decline of summer temperature during the herning stade sea level then stood at 40 m nn sedimentological considerations supported by counts of partly varved deposits indicate that the eemian lasted about 10 000 11 000 yr and the herning for several millennia

reconstruction of the grande pile eemian using inverse modeling of biomes and δ13c abstract a new method to reconstruct past climatic conditions between 130 and 100 ka bp from pollen and isotopic data is applied to a previously unanalyzed grande pile core gpxxi we applied the inverse mode to the biome4 vegetation model the method utilizes 13 c measured in parallel to the pollen samples as a constraint for the model first the biomes and the 13 c simulated by the model are compared with the biome allocation of the pollen data the 13 c to be simulated takes into account the degradation effect on the preserved organic matter this procedure allows the reconstruction of the mean annual temperature and precipitation as well as the mean temperatures of the warmest and coldest months we show that during the eemian sensu stricto the reconstructed precipitation is similar to modern values with low variability the cold stadials and the penultimate glaciation are characterized by very low precipitation amounts the temperature estimates however indicate differences with several oscillations identified the peak values are reached at about 124 125 ka bp but two other warm intervals are also identified the variations in temperature appear to be related to sea surface temperature oscillations in the north atlantic region and are also in agreement with the timing of ice sheet build up in the northern hemisphere seasonal variations are also identified in the estimated temperatures of the warmest and coldest months

biogenic silica record in lake biwa of central japan over the past 145 000 years abstract the record of the biogenic silica flux bsf g cm 2 103yr 1 in lake biwa reflects changes in diatom productivity in the lake and provides information regarding changes in paleoclimatic conditions the bsf record of lake biwa demonstrates five periods over the past ca 145 000 yr when the bsf values were significantly greater than 7 5 g cm 2 103yr 1 and five intervals when they were lower the data imply that paleoclimatic conditions were warmer and wetter from ca 123 000 to 115 000 103 000 to 95 000 88 000 to 72 000 57 000 to 32 000 yr b p and around ca 6000 yr b p when the bsf values were greater and relatively dry and cold from ca 141 000 to 123 000 yr b p and during intervals between two of the five warm and wet episodes when the bsf values were lower time series of the bsf record can be correlated with the record of biogenic silica content in lake baikal and the marine oxygen isotope stages 1 through 6 furthermore the bsf values varied with much higher amplitude during the last interglaciation than during the last glaciation probably implying that the diatom productivity in lake biwa was likewise more variable and had a larger range under interglacial conditions than under glacial conditions

diatom and geochemical evidence of mid to late holocene climatic changes at lake holzmaar west eifel germany abstract changes in diatom assemblages geochemistry and stable carbon isotope composition of bulk organic matter in a varved sediment section from lake holzmaar west eifel germany were used to infer mid to late holocene climatic changes and human impact from 6340 to 1470 cal yr bp shifts in total lacustrine primary production were derived from 13 c org values changes in non siliceous algae biomass productivity were deduced from accumulation rates of organic matter diatom valve accumulation rates and biogenic opal accumulation rates were used as proxies for diatom productivity and for siliceous phytoplankton abundance respectively based on weighted averaging of relative diatom abundance in subsamples qualitative changes in past trophic status were inferred accumulation rates of minerogenic material and the toc tn molar ratio permitted the deduction of past changes in allochthonous matter influx diatom assemblage composition showed statistically significant changes around 5130 3660 and 2900 cal yr bp whereas planktonic diatom productivity was subject to distinct shifts around 5900 5130 4500 3600 2660 and approximately 1630 cal yr bp and siliceous phytoplankton biomass changed ca 6100 4500 2660 1900 and 1700 cal yr bp causally determined changes in diatom assemblage composition and productivity for example due to shifts in nutrient ratios and or concentrations invoked by changes in lake circulation patterns precipitation rates and or erosion rates are discussed glacier fluctuations and lake level changes reported from other study sites in western europe support the finding that reconstructed lacustrine processes are at least indirectly linked to climate palynological and archaeological evidence however has shown a strong superimposition of lacustrine processes with local regional anthropogenic activity since the iron age

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

climate variations in europe over the past 140 kyr deduced from rock magnetism rapid shifts in climate during the last glacial are now well documented particularly from the oxygen isotope records of the two greenland ice cores grip1 2 and gisp23 in the grip record1 2 these climate events are also seen during the preceding eemian interglacial which may be an analogue for the future climate warmed by the greenhouse effect but these shifts are not found in the eemian section of the gisp2 core3 casting doubt on whether the rapid shifts in the grip oxygen isotope record really do represent a climate signal here we present magnetic susceptibility pollen and organic carbon records from maar lake deposits in the massif central france these data provide an independent record of past climate and we find that they correlate well with the ice core records during the last glacial during the eemian two rapid cooling events seen in our record also correlate with those seen in the grip ice core supporting the idea that rapid climate change did occur in the eemian interglacial and demonstrating that it extended to continental europe

ams radiocarbon analyses from lake baikal siberia challanges of dating sediments from a large oligotrophic lake abstract a suite of 146 new accelerator mass spectrometer ams radiocarbon ages provides the first reliable chronology for late quaternary sediments in lake baikal in this large highly oligotrophic lake biogenic and authigenic carbonate are absent and plant macrofossils are extremely rare total organic carbon is therefore the primary material available for dating several problems are associated with the toc ages one is the mixture of carbon sources in toc not all of which are syndepositional in age this problem manifests itself in apparent ages for the sediment surface that are greater than zero however because most of the organic carbon in lake baikal sediments is algal autochthonous in origin this effect is limited to about 1000 500 years which can be corrected at least for young deposits the other major problem with dating lake baikal sediments is the very low carbon contents of glacial age deposits which makes them extremely susceptible to contamination with modern carbon this problem can be minimized by careful sampling and handling procedures the ages show almost an order of magnitude difference in sediment accumulation rates among different sedimentary environments in lake baikal from about 0 04 mm year on isolated banks such as academician ridge to nearly 0 3 mm year in the turbidite depositional areas beneath the deep basin floors such as the central basin the new ams ages clearly indicate that the dramatic increase in diatom productivity in the lake as evidenced by increases in biogenic silica and organic carbon began about 13 ka in contrast to previous estimates of 7 ka for the age of this transition holocene net sedimentation rates may be less than equal to or greater than those in the late pleistocene depending on the site this variability reflects the balance between variable terrigenous sedimentation and increased biogenic sedimentation during interglaciations the ages reported here and the temporal and spatial variation in sedimentation rates that they imply provide opportunities for paleoenvironmental reconstructions at different time scales and resolutions

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

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

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

how long and how stable was the last interglacial abstract surface ocean indicators in the north atlantic during marine isotope stage mis 5 correlate closely with the vegetational succession in northeastern france the melisey i silty layer which marks the end of the last interglacial biozone in la grande pile pollen record appears coeval with the polar front advance c24 registered in the core v29 191 by a sharply increased presence of ice rafted detritus and the cold water foraminifer neogloboquadrina pachyderma sinistral since this event is younger than the peak of mis 5d the last interglacial as recognized in northern france correlates not only with the mis 5e but also with a substantial part of mis 5d the last interglacial in la grande pile was twice as long as the holocene and the climate in its first half was apparently not less stable than during the current interglacial if the future natural climates were to develop as analogs of the past then the onset of the next glacial environments on land would be still many millennia ahead

interactions of climate and land use documented in the varved sediments of seebergsee in the swiss alps this paper presents a multiproxy high resolution study of the past 2600 years for seebergsee a small swiss lake with varved sediments at the present tree line ecotone the laminae were identieed as varves by a numerical analysis of diatom counts in the thin sections the hypothesis of two diatom blooms per year was corroborated by the 210 pb and 137 cs chronology a period of intensive pasturing during the little ice age between ad 1346 and ad 1595 is suggested by coprophilous fungal spores as well as by pollen indicators of grazing by the diatom inferred total phosphorus by geochemistry and by documentary data the subsequent re oligotrophication of the lake took about 88 years as determined by the timelag between the decline of coprophile fungal spores and the restoration of pre eutrophic nutrient conditions according to previous studies of latewood densities from the same region cold summers around ad 1600 limited the pasturing at this altitude this demonstrated the socio economic impact of a single climatic event however the variance partitioning between the effects of land use and climate which was applied for the whole core revealed that climate independent of land use and time explained only 1 32 of the diatom data while land use independent of climate and time explained 15 7 clearly land use ineuenced the lake but land use was not always driven by climate other factors beside climate such as politics or the introduction of fertilizers in the seventeenth and eighteenth centuries also ine uenced the development of alpine pasturing

influence of terrestrial vegetation on sediment forming processes in kettle lakes of west central minnesota the composition magnetic characteristics and pollen content of sediments from two small kettle lakes near the prairie forest border in west central minnesota were used to infer changes in terrestrial vegetation shoreline erosion eolian inputs carbonate deposition and aquatic productivity several important changes in sediment stratigraphy coincide closely with changes in the terrestrial pollen assemblage accumulation rates of organic inorganic and carbonate sediment fractions as well as the concentration of magnetic particulates increased abruptly as prairie replaced pine forest and decreased gradually throughout the subsequent transitions to oak scrub and later mixed woodland results suggest that by its mediation of wind exposure local vegetation may affect 1 influx of eolian particulates 2 erosion of shorelines 3 water circulation and 4 carbonate equilibria in addition low rates of accumulation of organic matter and increased humidicity during periods of conifer vegetation suggest that humic matter leached from forest soils may influence lake water chemistry and reduce productivity changes in lake level caused by differential rates of evapotranspiration of the various vegetation types conifer forest deciduous hardwood forest brush scrub and prairie could not be detected sediment forming processes can therefore be altered by changes in local terrestrial vegetation through several mechanisms that are independent of changes in lake level

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

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

insolation regime in siberia as a major factor controlling diatom production in lake baikal during the past 800 000 years abstract a unique diatom biostratigraphy of the brunhes chron in lake baikal revealed by detailed studies of pelagic diatom paleo assemblages indicates that dramatic changes in insolation during the past 800 ka bp produced surprisingly rapid diatom speciation and extinctions the orbitally tuned age model allows the diatom assemblages to be compared with individual marine isotopic stages and substages during the brunhes most of the interglacial periods are characterized by explosive speciation and appearances of new pelagic planktonic diatom species in contrast most of the glacial periods are characterized by spectacular extinctions three broad periods characterized by different degrees of stability in the pelagic diatom assemblages are distinguished during the brunhes chron in the lake baikal sedimentary record mis 19 15e mis 15a 11 and mis 9 5 these periods are apparently associated with the long term changes in the amplitude of precessional insolation variations examination of individual interglacial periods further reveals the sensitivity of the baikal ecosystem to the regional energy balance virtually every precessional insolation peak during the early brunhes is characterized by a unique and peculiar paleo assemblage for the first time the siliceous microfossil record has demonstrated such a high degree of sensitivity to insolation forcing of regional climate despite the dramatic changes in the pelagic plankton driven by extreme climatic changes diatoms never went fully extinct during any glacial period although greatly or completely renewed during each subsequent interglacial the pelagic diatom assemblage still managed to return dominated by the new baikal endemic species the diatom assemblage observed in modern lake baikal despite being mostly endemic has formed during the past 50 100 ka and is therefore rather young these results demonstrate the remarkable capacity of this large freshwater system to sustain the dynamic stability on the large time scales

the classic marine isotope substage 5e since its identi cation nearly fty years ago marine iso tope stage 5 mis 5 has been placed onto absolute time scaleson the basis of three independent approaches cesare emiliani who set up the isotope stages emiliani 1955 depended onuranium series dating of the sediments a method that today isregarded as not generally capable of yielding useful precisionor accuracy broecker and van donk 1970 pioneered the ap proach of correlating to radiometrically dated marine coral ter races thishasbeenmuchaidedinrecentyearsbyimprovementsin the precision and accuracy of these age determinations thathave owed from the development of thermal ionization massspectrometry tims for uranium series dating edwards

the glacial inception as recorded in the northgrip greenland ice core timing structure and associated abrupt temperature changes the mechanisms involved in the glacial inception are still poorly constrained due to a lack of high resolution and cross dated climate records at various locations using air isotopic measurements in the recently drilled northgrip ice core we show that no evidence exists for stratigraphic disturbance of the climate record of the last glacial inception 123 100 kyears bp encompassing dansgaard oeschger events do 25 24 and 23 even if we lack sufficient resolution to completely rule out disturbance over do 25 we quantify the rapid surface temperature variability over do 23 and 24 with associated warmings of 10 2 5 and 16 2 5 c amplitudes which mimic those observed in full glacial conditions we use records of 18o of o2 to propose a common timescale for the northgrip and the antarctic vostok ice cores with a maximum uncertainty of 2 500 years and to examine the interhemispheric sequence of events over this period after a synchronous north south temperature decrease the onset of rapid events is triggered in the north through do 25 as for later events do 24 and 23 have a clear antarctic counterpart which does not seem to be the case for the very first abrupt warming do 25 this information when added to intermediate levels of co2 and to the absence of clear ice rafting associated with do 25 highlights the uniqueness of this first event while do 24 and 23 appear similar to typical full glacial do events

timing and duration of last interglacial conditions in europe a chronicle of a changing chronology abstract estimates of the length of the last interglacial in europe conventionally defined by the presence of forest as inferred from pollen diagrams have varied considerably here an account of recent developments largely instigated by a paper by kukla et al 1997 is presented these include the emergence of new records with improved chronologies and a re evaluation of previous assumptions of synchroneity between marine and terrestrial stage boundaries and also between northern and southern european changes the current scheme proposes that the onset of the last interglacial in europe started well into mis 5e after deglaciation was complete and was coincident with a rise to peak sea surface temperatures however the timing of the end of the last interglacial between northern and southern europe appears to have diverged considerably in the north the elimination of forest occurred ca 115 ka near the time of the mis 5e 5d transition while in the south tree populations persisted into the interval of global ice growth until the onset of significant ice rafting ca 110 ka this significant n s diachroneity may be a reflection of the effects of different bioclimatic parameters limiting tree growth in the two areas these developments highlight the problems of correlating records of different proxies and from different geographical regions

a high resolution 11 400 yr diatom record from lake victoria east africa abstract fine interval 30 45 yr sampling of a core from lake victoria s damba channel shows that numerous abrupt changes in the lake s diatom assemblages have occurred in response to climatic fluctuations over the past 11 400 14 c yr four distinct climatic phases bounded by sudden transitions are inferred 1 variably dry 11 400 10 000 yr b p 2 humid 10 000 7200 yr b p 3 more seasonal 7200 2200 yr b p and 4 more arid 2200 0 yr b p with a dry little ice age event 600 200 yr b p the diatom inferred paleoclimatic history for northern lake victoria closely resembles that inferred from a well dated pollen record from pilkington bay spectral analysis of the diatom record reveals strong periodicities including globally distributed 2360 2550 1400 1030 1130 and 500 cal yr cycles repeated rapid shifts between aulacoseira and nitzschia dominated diatom assemblages suggest that post 1960 changes in the lake s phytoplankton communities have had earlier climate driven analogs

increasing vegetation and climate gradient in western europe over the last glacial inception 122 110 ka data model comparison high resolution terrestrial pollen and marine planktic and benthic isotopes coarse fraction and n pachyderma s analyses have been performed in the marine isotope stage mis 5 interval of images core md99 2331 retrieved in the northwestern iberian margin this study shows the occurrence of a zeifen interstadial stadial succession on land and in the ocean during the first part of mis 5e in northwestern iberia the eemian is marked from 126 to 122 ka by the development of deciduous quercus forest at the same time as mediterranean forest colonised southern iberia and deciduous quercus corylus forest occupied northernmost european regions from 121 to 115 ka carpinus betulus forest developed in nw iberia indicating a winter cooling by 2degreesc on land and an increase in annual precipitation by 100 200 min along with a sea surface temperature sst decreasing trend off iberia a similar cooling has been documented at the same time in northern germany 52degreesn by the replacement of deciduous forest by coniferous abies picea formations implying a southward displacement of the deciduous tree line between similar to60degreesn and 50degreesn as early as 120 ka the southward migration of the tree line between 72degreesn and 58degreesn simulated by the earth model of intermediate complexity mobidic from 122 and 120 ka and considered as a major process to initiate the last glaciation is therefore compatible with data between 115 and 110 ka the substantial ice accumulation in northern high latitudes mis 5e 5d transition was synchronous with successive drops c26 and c25 in northeastern atlantic sst in northwestern iberia abies pinus trees developed at the expense of quercus carpinus forest a tundra like environment occupied northern germany marking the end of the interglacial in northwestern europe at 115 ka and boreal forest likely colonised northeastern france the first displacement of the vegetation belts at 121 ka was enhanced at 115 ka indicating an amplification of the vegetation and climate gradients in northeastern atlantic and european borderlands probably related with the well developed ice caps at that time the comparison between the general trend in the estimated and simulated mobidic winter and summer temperatures for latitudes between 35 and 45degreesn shows that both follow quite straightforwardly the precession signal although the simulated and reconstructed temperatures agree better in the south than north of 40degreesn annual precipitation is exhibiting opposite trend in the data and in the model this contradiction is likely the fact that the zonal climate simulated by the model may not accurately represent the regional climate features as reconstructed from the pollen c 2004 elsevier b v all rights reserved

stable climatic conditions in central germany during the last interglacial stable isotopic data from the high resolution limnic sequence in the opencast mine at grobern central germany confirm the relatively stable climate of the last interglacial deduced from pollen analyses after significant warming during the transition from the saalian to the eemian stable warm climatic conditions set in once the climatic optimum was reached in the course of biozones e4 to e5 from the middle of biozone e6b a gradual temperature decrease can be observed reaching a minimum at the start of biozone e7 the division of the early weichselian glacial in central germany into two stadials herning rederstall and two interstadials brorup odderade is also documented by the findings copyright 2000 john wiley sons ltd

submillennial environmental fluctuations during marine oxygen isotope stage 2 a comparative analysis of diatom and pollen evidence from lago grande di monticchio south italy high temporal resolution pollen and diatom analyses carried out on sediments from lago grande di monticchio span the interval 23 700 21 200 calendar yr bp a brief interstadial during marine oxygen isotope stage 2 both records exhibit marked changes that are interpreted as responses to climatic changes the diatoms and terrestrial vegetation appear to respond at the same time any relative lag in the response of the vegetation was less than the ca 60 yr resolution of the two records the interval coincides at least in part with the campo imperatore stade when the gran sasso ice sheet reached its maximum extent and water level was high in the fucino lake correlation of the marked environmental oscillation with one of the dansgaard oeschger events recorded by stable oxygen isotope records from the greenland ice cap is proposed this follows an interval interpreted as having a cold dry climate and correlated with a heinrich event in the north atlantic together the two records enable a multifactorial interpretation of the palaeoclimate changes that characterise the oscillation providing additional insight to that obtained from studies of ice and ocean sediment cores especially with respect to the seasonality of temperature and precipitation copyright 1999 john wiley sons ltd

similarity of vegetation dynamics during interglacial periods the velay sequence france provides a unique continuous palynological record spanning the last four climatic cycles a pollen based reconstruction of temperature and precipitation displays marked climatic cycles an analysis of the climate and vegetation changes during the interglacial periods reveals comparable features and identical major vegetation successions although marine isotope stage mis 11 3 and the holocene had similar earth precessional variations their correspondence in terms of vegetation dynamics is low mis 9 5 7 5 and especially 5 5 display closer correlation to the holocene than mis 11 3 ecological factors such as the distribution and composition of glacial refugia or postglacial migration patterns may explain these discrepancies comparison of ecosystem dynamics during the past five interglacials suggests that vegetation development in the current interglacial has no analogue from the past 500 000 years

rock magnetic properties of eemian maar lake sediments from massif central france a climatic signature the hypothesis of a climate variability within the last interglacial eemian suggested by oxygen isotope data of a greenland ice core grip was later supported by magnetic susceptibility organic matter and pollen signatures in the eemian lake sediments of the lac du bouchet france in the present paper we analyse in detail the rock magnetic properties of these sediments in order to determine the origin of the magnetic susceptibility variations furthermore in order to verify the empirical relation between magnetic susceptibility and climate we studied two eemian sequences from neighbouring lakes lac st front and ribains maar lake rock magnetic investigations mainly consisted of analyses of anhysteretic and isothermal remanent magnetizations along with hysteresis measurements carried out on pilot samples lac du bouchet susceptibility variations are at least partly affected by postdepositional magnetite dissolution lac st front sediments show a complex behaviour resulting in partly contradicting interpretations of rock magnetic parameters possible explanations may be the presence of a very fine grained magnetite or the presence of maghemite ribains maar lake sediments show a homogeneous magnetic mineralogy without major variations in most of the rock magnetic parameters susceptibility records of the three lakes were compared under the simplified assumption that magnetic susceptibility mainly reflects variations of the detrital titano magnetite input only a poor correlation between the three eemian susceptibility sequences is observed suggesting that local effects including dissolution and dilution effects may have altered the original detrital climatic signal the purely detrital origin of the lac du bouchet eemian susceptibility variations must thus be questioned but it nevertheless appears to be the only lake whose susceptibility variations can tentatively be correlated with the grip eemian oxygen isotope record

timing and duration of the last interglacial evidence for a restricted interval of widespread coral reef growth abstract we report new mass spectrometric u series ages for eight last interglacial fossil reefs along the continental margin of western australia corals were selected in growth position from localities that are characterized by apparently low levels of diagenesis and relative tectonic stability so that the fossil reefs provide critical information on last interglacial sea levels without requiring corrections for tectonic movements in addition we have improved the constraint on the timing of onset of reef growth by recovering drill core coral from the base of the reefs uranium and thorium isotopes were measured with high levels of precision leading to improvements in age resolution and allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified and discarded these data supplement our previous results for rottnest island and leander point leading to more than seventy mass spectrometric u series ages from which constraints can be placed on the timing duration and character of the last interglacial sea level highstand reliable ages show that reef growth started contemporaneously at 128 1 ka along the entire western australian coastline while relative sea levels were at least 3 m above the present level because western australia is located far from the former penultimate glacial maximum ice sheets and are not significantly effected by glacial unloading these data constrain the timing of onset of the last interglacial period to 128 1 ka assuming reef growth started soon after sea level approached interglacial levels a unique regressive reef sequence at mangrove bay constrains the timing of termination of the last interglacial period to 116 1 ka the major episode of reef building however both globally and locally along the western australian coast is restricted to a very narrow interval occurring from 128 ka and 121 ka suggesting that global ocean surface temperatures were warm and or sea levels were stable enough to allow prolific reef growth only during the earlier part of the last interglacial

abrupt temperature changes in the western mediterranean over the past 250 000 years a continuous high resolution western mediterranean sea surface temperature sst alkenone record spanning the past 250 000 years shows that abrupt changes were more common at warming than at cooling during marine isotope stage mis 6 sst oscillated following a stadial interstadial pattern but at lower intensities and rates of change than in the dansgaard oeschger events of mis 3 some of the most prominent events occurred over miss 5 and 7 after prolonged warm periods of high stability climate during the whole period was predominantly maintained in interglacial interstadial conditions whereas the duration of stadials was much shorter

high resolution palynological record off the iberian margin direct land sea correlation for the last interglacial complex abstract we present high resolution pollen dinocyst and isotopic data for the last interglacial complex from marine core md952042 southwestern margin of the iberian peninsula 37 48 n 10 10 w 3148 m direct land sea correlation from this core indicates that during this period north atlantic sea surface temperatures were in phase with iberian climate our palynological analysis suggests a younger dryas like event at the marine isotope stage mis 6 5 transition the analysis also indicates that the eemian spans from the lightest isotopic values of mis 5e ca 126 ky bp to the heavier isotopic values towards the mis 5e 5d transition therefore the eemian is not entirely equivalent to mis 5e pollen analysis identifies four climatic phases of low amplitude during the eemian a mediterranean climate in southwestern europe is gradually replaced by oceanic conditions the middle of the eemian is characterized by an increase in precipitation on the land and ocean associated with a slight cooling this seems to be the result of a displacement of the polar front as far south as southern europe during this period after the eemian three relatively short climatic phases on land melisey i st germain ia and montaigu cold event occurred contemporaneously with three shifts of sea surface temperatures the montaigu event first identified in terrestrial pollen sequences is therefore also recorded in core md952042 on the basis of pollen dinocyst and planktonic isotopic data our results also show that the warm periods of mis 5 are not characterized by similar climatic conditions on land

a diatom record for the past 400 ka from lake biwa in japan correlates with global paleoclimatic trends abstract detailed diatom records from a 140 m sediment core with a time resolution of approximately 1000 1500 yr were obtained from lake biwa to examine possible correlations between diatom concentrations and paleoclimatic changes during the last approximately 400 ka in the sediments the diatom assemblages are generally dominated by planktonic diatoms the diatom stratigraphy is characterized by four zones with distinctly higher concentration values and 12 horizons with low concentration values diatom records from the 140 m core and another core indicate that these changes were not local phenomena but occurred throughout the lake basin comparison of diatom concentration records with pollen records from lake biwa sediments indicates that higher diatom concentrations represent warmer and wetter climatic conditions and that lower concentrations represent colder and drier climatic conditions comparison of diatom records from lake biwa with marine oxygen isotopic records shows that the number of peaks and their relative amplitudes are similar in both profiles therefore peaks and drops in diatom concentration profile might correlate with most oxygen isotopic events this finding indicates that during approximately the last 400 ka the changes in diatom concentration represented as diatom productivity in lake biwa correlate closely with global paleoclimatic changes at the scale of the milankovitch cycle precession cycles of 23 and 19 ka and that diatom concentration was higher during warm events and lower during cold or cooling events

stalagmite evidence for the precise timing of north atlantic cold events during the early last glacial evidence of millennial scale cold events following the last interglacial are well preserved in north atlantic marine cores greenland ice and pollen records from europe however their timing was previously undetermined by radiometric dating we report the first precise radiometric ages for two such events c23 105 1 0 9 ka to 102 6 0 8 ka and c24 112 0 0 8 ka and 108 8 1 0 ka based on stable carbon and oxygen isotope measurements on a stalagmite from italy cc28 in addition to providing new information on the duration of these events in southern europe the age data provide invaluable tuning points for the melisey i c24 and montaigu c23 pollen zones identified in western europe the former event is of particular significance because it represents the end of the eemian interglacial forest phase in western europe the new age data will also allow fine tuning of the timing and duration of greenland stadial 24 equivalent to c23 in the north greenland ice core project ice core and via a common gasage chronology tuning of the vostok and epica european project for ice coring in antarctica ice cores

continental climate response to orbital forcing from biogenic silica records in lake baikal changes in insolation caused by periodic changes in the earth s orbital parameters provide the primary forcing for global ice ages1 6 but it is not clear to what extent the climates in continental interiors are controlled directly by regional variations in insolation and to what extent they are driven instead by the highly nonlinear response of the oceans and ice sheets here we investigate this question using the record of biogenic silica in lake baikal as a proxy for climate change in this high latitude mid continental region we find a good correlation between this record and that of marine oxygen isotopes4 over the past 250 kyr the baikal record exhibits both a strongly nonlinear component manifested in a 100 kyr periodicity and weaker direct insolation components manifested in the 41 kyr obliquity and 23 and 19 kyr precession orbital cycles these results show that even though extreme continental climates such as this are influenced directly by insolation variations they are dominated by the nonlinear rhythm of the oceans and ice sheets

timing and progression of the last interglacial derived from a high alpine stalagmite 1 u th dating and oxygen isotope analysis of a stalagmite from spannagel cave in the austrian alps provides information about the timing and progression of the last interglacial climate we determined two distinct growth intervals warm climate from 130 7 thousand years ka before the present to 130 0 ka and from 125 7 ka to 118 2 ka the latter containing two periods of ceased stalagmite growth colder climate at around 123 8 ka and 120 5 ka high resolution 18o analysis of stalagmite spa 50 reveals a clear regular cyclic pattern with periods of 197 109 and 21 years which are likely to be related to the suess gleissberg and hale cycles respectively indicating that eemian climate in the alps was forced by the sun

diatom responses to limnological and climatic changes at ribains maar french massif central during the eemian and early wurm abstract high resolution diatom analysis was carried out to assess the limnological and climatic changes that took place at ribains maar french massif central during the late pleistocene 131 105 ka bp with a focus on the eemian interglacial in particular numerical analyses were used to show that most of the variability in the fossil diatom assemblages was due to climate independently from the changes in the lake catchment vegetation as represented by pollen data diatom based quantitative reconstructions of the past limnological conditions as well as a comprehensive literature review on the auto ecological requirements for the principal diatom taxa were used to interpret the record an absolute time scale for the sequence was derived by matching the major pollen shifts with the radiometrically dated changes in oxygen isotopes observed in italian stalagmites this study shows that at ribains maar the transition from the riss saalian glacial to the eemian interglacial was marked by a gradual increase in the contribution of spring blooming diatom species indicating a longer growing season and milder winter spring conditions at that time a short cooling event interrupts this trend and may correspond to a stadial at the start of the eemian a peak in benthic taxa and the suppression of spring blooming flora probably reflects the effects of deglaciation on the catchment during the eemian interglacial itself three main phases were distinguished within the diatom record the first phase 8000 years in duration was dominated by stephanodiscus minutulus which suggests that intense mixing in the water column took place during spring the pollen record was simultaneously dominated by quercus and corylus that typify this phase as the climatic optimum of the eemian the second phase almost equal in duration to the first phase 7000 years is generally dominated by cyclotella taxa and suggests a less productive lake and much reduced period of spring mixing compared with the first phase in the pollen diagram this corresponds to an interval dominated by carpinus picea abies that indicates a cooler and wetter climate the third and last phase of the eemian 2000 year long saw the return to stephanodiscus dominated assemblages indicating a warming that may correspond to the dansgaard oeschger event 25 identified in the greenland ice core record in the early stage of the wurm glacial weichselian assemblages in the melisey i stadial 3000 year long were dominated by either aulacoseira subarctica or asterionella formosa which suggest colder spring conditions than during the late eemian but not as cold as the ones indicated by the pollen record stephanodiscus spp again dominate during the saint germain ia interstadial 5000 year long suggesting a return to the conditions that prevailed before the melisey stadial in agreement with the pollen record the record ends with the montaigu cold event which is characterised by a pinus peak in the pollen record and corresponds to a large abundance of a subarctica in the diatom sequence throughout the eemian the abundance of stephanodiscus spp which is thought to be driven by winter conditions show cyclic fluctuations that most likely match the cooling events identified in a pollen record from germany variation in insolation throughout the eemian may have been the driving factor behind the species succession observed in the diatom sequence while this study demonstrates that diatom analysis of lake sediment can provide very detailed information on long term climate change a review of the few other diatom investigations published on european eemian deposits shows that this technique has been so far seldom used to its full potential in this context in central and southern europe

chrysophycean microfossils in paleolimnological studies abstract the chrysophyceae represent a diverse group of algae with approximately 1000 described species most of which are planktonic and found in oligotrophic lakes a characteristic feature of this class is the endogenous formation of a siliceous resting stage known as a statospore vegetative cells in the family mallomonadaceae are covered by overlapping siliceous scales that are often sculptured and ornamented both the statospores and scales are species specific and because they are siliceous they are usually well preserved in lake sediments this paper reviews the applicability of these microfossils in the interpretation of past lake conditions

eemian crustal deformation in the eastern baltic area in the light of the new sites at peski russia and pohja uhtju estonia abstract several eemian mikulino marine deposits are known from the northwestern part of russia and from estonia the best known deposits are situated at mga russia and at prangli estonia two new sites with clayey and silty deposits covered by till were studied for pollen and diatoms at peski russia and pohja uhtju estonia at peski the deposit representing the eemian interglacial is 3 8 m thick at the depth of 13 4 9 6 m above present sea level at pohja uhtju the deposit representing the eemian is 3 5 m thick at the depth of 47 9 51 4 m below present sea level although peski is situated at a higher altitude than pohja uhtju at present the diatom stratigraphy at these sites indicates deeper and more saline conditions in the peski area than at pohja uhtju during the eemian this result is similar to some previous studies which indicate that although the russian deposits e g peski mga are now at a higher altitude than those in estonia pohja uhtju and prangli the diatoms in the russian deposits are indicative of a considerable depth of water during the time of deposition these deposits suggest that the eemian shore levels ascend from estonia eastwards while the late weichselian and holocene shorelines tilt downwards in the same general direction the present material from estonia and northwestern part of russia shows marked differences between the eemian and late weichselian holocene crustal deformations which probably resulted from different ice loads during the final glaciation phases and probably also from different deglaciation patterns during the saalian and late weichselian

hydrography and mollusc faunas of the baltic and the white sea north sea seaway in the eemian abstract palynologically dated mollusc and cirriped faunas from a region extending from the north sea through the baltic and karelia to the arkhangelsk region show that the hydrography of the baltic was very different from the holocene for 2 2 5 ka in the early eemian a seaway existed from the barents to the north sea through karelia until it was severed at the present continental watershed to the north of lake onega after this the ladoga onega trough remained an arm of the baltic for several millennia the benthic faunas are comparable to the holocene but their boundaries were displaced much further into the baltic notable differences from the holocene are the absence or rarity of the macoma balthica biocoenosis and the presence of cold portlandia dominated biocoenoses in karelia in the belt sea and western baltic winter sea surface temperatures and salinity were higher than now by ca 6 c and 15 and the distinctly brackish top layer was missing at the same time cold bottom water 2 5 c with a tendency to anoxia characterised the karelian arm of the baltic water exchange through this area was inhibited by the constriction to the north of lake onega and the basin and threshold bathymetry water transport through the white sea baltic seaway was too sparse to play an active role in the north atlantic surface circulation or climatic change in the region the high salinity and temperature in the belt sea and western baltic persisted throughout the eemian and are explained by wider and deeper passage from the north sea to kattegat wider straits through denmark higher salinity in the north sea higher evaporation as well as more dispersed fresh water supply the advection of oceanic water into the baltic culminated in the early eemian before the carpinus zone and probably resulted in an oceanic climate in the baltic region while at the same time cold winters produced cold bottom water in the karelian arm

a long pollen record from lac du bouchet massif central france for the period ca 325 to 100 ka bp ois 9c to ois 5e abstract pollen analysis was carried out on sediments older than the wurm pleniglacial ois 4 in two new sequences h and i derived from the centre of lac du bouchet massif central the inferred vegetation history enables for the first time in france five temperate episodes to be defined which pre date the last interglacial these temperate episodes alternate with episodes during which the changes in vegetation are indicative of glacial climates comparison of these climatic episodes with the oceanic isotope record shows that the pollen record of sequences h and i from lac du bouchet spans the time interval from ois 9c ussel interstadial to ois 5e ribains eemian interglacial in the organic sediments from the amargiers interstadial ois 9a a trachytic layer ar ar dated to ca 275 ka enables a correlation to be established with the upper part of a sequence derived from the nearby praclaux crater the lower part of this sequence being of holsteinian age ois 11c the cross dating of the pollen sequences from lac du bouchet cores h i and d and from praclaux provides a complete record from the massif central southern france of successive glacial and interglacial episodes that span the last ca 400 ka that is the interval from the holsteinian to the holocene

deconstructing terminations i and ii revisiting the glacioeustatic paradigm based on deep water temperature estimates benthic and planktonic oxygen isotope 18occ and mg ca analyses in two cores from the northeast atlantic have permitted the reconstruction of surface and deep water temperature tdw and 18o 18ow variations across the last two deglaciations these records allow the timing of de glacial melt water pulses reaching the northeast atlantic to be compared with the evolution of local deep water tdw 18ow conditions although each glacial termination is unique in detail a similar pattern of hydrographic change is reconstructed for both deglaciations with the first major decrease in deep water 18ow due to sea level and or purely local deep water change occurring in parallel with the onset of intensely cold glacial surface water temperatures and prior to a terminal ice rafting and melt water event the evolution of deep water across both de glaciations involved two transient incursions of cold low 18o water into the deep northeast atlantic the second of which was particularly pronounced each time these pulses of cold deep water are interpreted to reflect the incursion of water directly analogous to modern antarctic bottom water aabw and containing a significant component of brine rejected during sea ice formation the results presented here show that the same type of transient changes in deep water circulation that occurred across termination i also occurred across termination ii and that as a result of these deep ocean changes the timing of each benthic 18o termination cannot precisely reflect the timing of de glacial sea level change as many palaeoceanographic interpretations and some controversies are prone to assume such imprecision in timing especially may well extend to marine isotope stage mis boundaries in general as a principle of hydrographic variability and its expression in the geological record

relation of subtropical atlantic temperature high latitude ice rafting deep water formation and european climate 130 000 60 000 years ago abstract a new high resolution record of sea surface temperature from the subtropical western north atlantic documents a series of abrupt coolings within marine isotope stage 5 which can be objectively correlated with marine core evidence for increased ice sheet discharge at subpolar latitudes and reduced north atlantic deep water formation these results indicate that ice sheet forcing of deep ocean circulation influenced surface temperatures over much of the north atlantic a proposed correlation to the pollen record of grande pile france indicates that each cold event seen in the pollen sequence has a unique counterpart in the record of subtropical ocean temperature if this correlation is correct it suggests that the warmest part of the european eemian ended suddenly in response to oceanographic changes and that the subsequent post temperate phase of the eemian extended well into the interval of ice sheet growth corresponding to marine isotope substage 5d

the last climatic cycle at la grande pile vosges france a new pollen profile a new pollen diagram has been made from an old unanalyzed core from la grande pile gp xx correlations with the previous work of woillard 1975 1978 leads to the following conclusions the end of the eemian was marked by a minor climatic change prior to the melisey i stadial the ognon ii and ognon iii interstadials are not consistent and correspond to the level of reworking of mesophilous taxa during the last pleniglacial the limitations of the botanical interpretation of pollen spectra from the last pleniglacial are underlined lastly bruckenthalia and larix are identified for the first time at la grande pile the respective roles of these taxa following the eemian are additional arguments for correlating the st germain i and ii with the early weichsel interstadials in the north of middle europe

problems of the duration of the eemian interglacial in europe north of the alps abstract suggestions that the duration of the eemian interglacial was about 11 000 yr based on annually laminated sediment sequences in germany have been challenged in favor of a much longer interval however biostratigraphic evidence demonstrates why the eemian sequences at grande pile and ribains cannot be reliably used for alignment with the marine sequence as applied by kukla et al 2002 this issue to estimate the duration of this interglacial the long chronology they propose would imply not just coniferous but for up to 5000 yr fully temperate forest in central france coexisting with treeless heath and steppe tundra conditions in northwestern europe an unlikely climatic and ecological scenario the proposal that the eemian interglacial in western europe lasted for 17 000 or even 23 000 yr is rejected a duration of no more than 13 000 yr is preferred at least for sites north of the alps and pyrenees the duration of temperate conditions in the mediterranean region is less certain

cyclic climate fluctuations during the last interglacial in central europe differentiating natural climate change from anthropogenic forcing is a major challenge in the prediction of future climates in this context the investigation of interglacials provides valuable information on natural climate variability during periods that resemble the present this paper shows that natural cyclic changes in winter climates affected central european environments during the last interglacial i e the eemian 126 110 ka as a result of the extraordinarily high counting sums performed at eemian pollen samples it was possible to reveal a robust presence absence pattern of the insect pollinated and therefore in the pollen rain underrepresented taxon hedera this plant is known to require the influence of oceanic winter climates i e moist and mild in northwest and central europe by analogy with recent findings from the north atlantic s holocene interglacial the trigger of the eemian climate variability may have been changes in solar activity possibly amplified by changes in north atlantic ocean currents and or in the north atlantic oscillation our findings suggest natural cyclic changes to be a persistent feature of interglacial climates

lake baikal record of continental climate response to orbital insolation during the past 5 million years the sedimentary record of biogenic silica from lake baikal in south central siberia suggests that this region of central asia was impacted by two major cooling episodes at 2 8 to 2 6 and 1 8 to 1 6 million years ago the spectral evolution of this continental interior site parallels the evolutionary frequency spectra for various marine oxygen isotope records in the baikal record the 41 000 year obliquity cycle is particularly strong from 1 8 to 0 8 million years ago variance in the 100 000 year eccentricity band increases during the past 0 8 million years the expected precession frequency of 23 000 years is highest during the past 400 000 years the modulation of the predicted 23 000 and 41 000 year insolation forcing by the 100 000 and 400 000 year eccentricity bands indicates that the transfer of variance from the precession and obliquity frequencies to the eccentricity part of the spectrum occurred in the eurasian continental interior as well as in tropical and high latitude ocean sites

rissian eemian and wurmian coleoptera assemblages from la grande pile vosges france abstract the grande pile peat bog sequence is one of the few west european sites that cover the entire time span of the last major climatic cycle 140 000 years a recent program of coring has provided material for insect analysis the aim of this palaeoentomological study is to interpret the environmental and climatic evolution from the end of the rissian glaciation to the holocene using subfossil coleoptera the studied samples yielded 394 taxa of coleoptera half of them identified to species level 19 of which do not belong to the present day french fauna the large number of taxa suggests a wide variety of habitats and provides much detailed palaeoecological evidence for the period studied the lowermost sediments of the sequence corresponding to the end of the rissian glaciation were deposited under very cold conditions in a tundra environment this is succeeded by a forest period in which two cool interludes of grassland environment occur although these periods are decidedly poor in tree dependent coleoptera they do not contain any really cold adapted taxa they divide the forest phase into three periods the first one corresponding to the eemian interglacial shows an early stage in which the beetle fauna is characterized by species dependent on deciduous trees a later stage in which this fauna is mixed with many conifer dependent elements some of which e g platypus oxyurus suggest warmer and perhaps wetter climatic condition than today the two later woodland periods yielded coleopteran assemblages rather similar to those recorded in the second part of the eemian i e with both deciduous and conifer dependent taxa there is some evidence to suggest that these two periods were slightly cooler than the eemian proper marked climatic deterioration becomes obvious in the upper half of the sedimentary sequence attributed to the last glacial period wurm with the reappearance of tundra beetle assemblages sediment and insect evidence suggest that the climate was extremely cold and continental at la grande pile at about 30 000 b p a comparison of the insect analysis with previous palynological works enables precise correlation between the results provided by these two independent approaches however large numbers of running water coleoptera in the forest periods replaced by standing water coleoptera in cold periods raise questions concerning the lacustrine origin of the sedimentation at la grande pile

eemian to early wurmian climate dynamics history and pattern of changes in central europe abstract high resolution pollen records from the northern alpine foreland are used to evaluate the patterns of climate change during the period between the late eemian interglacial marine oxygen isotope stage ois 5e about 115 ky ago and the end of the st germain ii ois 5a dansgaard oeschger interstadial d o is21 about 75 ky ago for the quantitative climate interpretation of the fossil pollen assemblages we compare two different methods a modern analogue technique and a mutual climatic range approach the results not only reveal major climatic changes at the transition to stadials and interstadials but also indicate short term oscillations which are followed by an almost full return to the preceding climate conditions and components of gradual trends resembling saw tooth structures based on the pollen data the climate reconstructions suggest that the optimum in st germain ii ois 5a d o is21 in winter temperatures was about 0 8 to 1 4 c and in summer temperatures about 0 7 to 1 2 c warmer than the optimum in st germain i ois 5c d o is22 to is24 the severe and short time montaigu cold event iceberg discharge event c23 clearly divided st germain i into two thermal periods thus st germain ia d o is24 preceding the montaigu event is slightly more favourable than the following st germain ic d o is23 since several climate oscillations occurred during these interstadials they show only limited stability with respect to the stadial periods the results reveal a coherent pattern for all records winter temperatures during melisey ii ois 5b c21 are about 1 to 4 c lower than those during melisey i ois 5d c24 as regards short term climate changes during melisey i and melisey ii consistent amelioration episodes may be distinguished during these intervals

quantitative reconstruction of the last interglacial vegetation and climate based on the pollen record from lake baikal russia changes in mean temperature of the coldest t c and warmest month t w annual precipitation p ann and moisture index were reconstructed from a continuous pollen record from lake baikal russia the pollen sequence con01 603 2 53 57 n 108 54 e was recovered from a 386 m water depth in the continent ridge and dated to ca 130 114 8 ky bp this time interval covers the complete last interglacial li corresponding to mis 5e results of pollen analysis and pollen based quantitative biome reconstruction show pronounced changes in the regional vegetation throughout the record shrubby tundra covered the area at the beginning of mis 5e ca 130 128 ky consistent with the end of the middle pleistocene glaciation the late glacial climate was characterised by low winter and summer temperatures t c 38 to 35 c and t w 11 13 c and low annual precipitation p ann 300 mm however the wide spread of tundra vegetation suggests rather moist environments associated with low temperatures and evaporation reconstructed 1 tundra was replaced by boreal conifer forest taiga by ca 128 ky bp suggesting a transition to the interglacial taiga dominant phase lasted until ca 117 4 ky bp e g about 10 ky the most favourable climate conditions occurred during the first half of the li p ann reached 500 mm soon after 128 ky bp however temperature changed more gradually maximum values of t c 20 c and t w 16 17 c are reconstructed from about 126 ky bp conditions became gradually colder after ca 121 ky bp t c dropped to 27 c and t w to 15 c by 119 5 ky bp the reconstructed increase in continentality was accompanied by a decrease in p ann to 400 420 mm however the climate was still humid enough 0 9 to support growth of boreal evergreen conifers a sharp turn towards a dry climate is reconstructed after ca 118 ky bp causing retreat of forest and spread of cool grass shrub communities cool steppe dominated the vegetation in the area between ca 117 5 ky and 114 8 ky bp suggesting the end of the interglacial and transition to the last glacial mis 5d shift to the new glaciation was characterised by cool and very dry conditions with t c 28 to 30 c t w 14 15 c p ann 250 mm and 0 5

high resolution sediment and vegetation responses to younger dryas climate change in varved lake sediments from meerfelder maar germany abstract this work focuses on a 1900 year section of varved sediments from lake meerfelder maar mfm extending from the late allerod to the preboreal varve counting provides the chronological framework and determines the length of younger dryas to 1025 1090 years a strong relation between climate change environment response and depositional processes has been found in consequence varve microfacies variations are a sensitive proxy for environment changes these are reflected for example in erosion processes within the lake s catchment minerogenic input and lake productivity diatom blooms the observed varve changes have been quantified by multiproxy analyses of physical and chemical sediment parameters with a resolution of between 8 and 40 years depending on sedimentation rate in addition high resolution palynological investigations provide the biostratigraphical subdivision based on changes in the vegetation occurring during the same time interval varve observations reveal that environment changes at the beginning and the end of the younger dryas occurred within 20 50 years furthermore sediment and vegetation changes were synchronous within the actual precision of the mfm and grip chronologies divergence of only a few decades terrestrial responses in western europe occurred quasi synchronous to temperature changes in greenland

north atlantic current and european environments during the declining stage of the last interglacial this paper provides a tentative reconstruction of environmental shifts in europe associated with changes of the north atlantic current and related meridional sea surface temperature sst gradients during most of the eemian interglacial ca 126 115 ka the north atlantic current extended far north into the nordic seas and european environments were comparable to those of the holocene however ca 115 ka an sst drop in the nordic seas marked a southward displacement of the north atlantic current this hydrographic shift was associated with substantial cooling in northern europe and drier conditions in the mediterranean region the polar timberline retreated southward from 69 n in northernmost scandinavia to 52 n in central europe and thermophilous deciduous trees became extinct north of the 48th parallel woodlands persisted in southern europe for another 5 k y well into marine isotope substage 5d these conditions indicate steep vegetation and climate gradients at the inception of the last glacial

the evolution of a tropical rainforest grassland mosaic in southeastern brazil since 28 000 14c yr bp based on carbon isotopes and pollen records the lack of paleoecological records from the montane atlantic rainforest of coastal brazil a hotspot of biological diversity has been a major obstacle to our understanding of the vegetational changes since the last glacial cycle we present carbon isotope and pollen records to assess the impact of the glaciation on the native vegetation of the serra do mar rainforest in sao paulo brazil from ca 28 000 to 22 000 14c yr bp a subtropical forest with conifer trees is indicative of cool and humid conditions in agreement carbon isotopic data on soil organic matter suggest the presence of c3 plants and perhaps c4 plants from 28 000 to 19 000 14c yr bp the significant increase in the sedimentation rate and algal spores from 19 450 to 19 000 14c yr bp indicates increasing humidity associated to an erosion process between 19 000 and 15 600 14c yr bp from 15 600 14c yr bp to present there is a substantial increase in arboreal elements and herbs indicating more humid and warmer climate from 19 000 to 1000 14c yr bp 13c values indicated the predominance of c3 plants these results are in agreement with studies in speleothems of caves which suggest humid conditions during the last glacial maximum

eemian lake development hydrology and climate a multi stratigraphic study of the hollerup site in denmark abstract a classic northwest european open section with lacustrine eemian sediments hollerup has been studied with respect to sedimentology geochemistry stable isotopes diatoms and mineral magnetic analyses and correlated by geochemistry and diatoms to a previously pollen analysed section by andersen 1965 this correlation has enabled the section to be related to muller s 1974 tentative eemian absolute chronology and shows that the hollerup eemian sediments appear to cover c 11 000 yr our studies show that the onset of the eemian was characterized by a major lake level rise followed by an almost 3000 yr long period of high but oscillating lake levels it is argued that the latter part of this period of highly maritime climate can be defined as the eemian climatic optimum this period was interrupted by a few hundred years long phase of low lake level coinciding with the immigration of spruce followed by medium high lake levels the next c 3500 yr coinciding with the carpinus pollen zone seem to have been characterized by fairly humid and mild conditions although slightly more arid than during the preceding optimum the carpinus period ended with a more than 1000 yr long gradual lake level fall and this period of lake level change concurring with the transition into the pinus pollen dominated period terminated with an extreme low lake level event this 300 500 yr long arid phase coincides with a distinct peak in pine pollen and was followed by higher but slightly oscillating lake levels in a cooler climate the end of the eemian seems to have been characterised by a gradual cooling until almost pure clastic sedimentation and a marked expansion of herb pollen grains mark the onset of the weichselian based on regional correlations to other european terrestrial and north atlantic marine proxy records we argue that the distinct hydrologic and climatic events displayed in the hollerup record were possibly caused by a combination of sea level changes changes in the hydrologic cycle and changing oceanic circulation patterns the latter two may have been triggered by the opening and closure of the baltic sea white sea connection the initial build up of continental ice sheets and the first major impacts of meltwater induced freshwater in key areas for thermohaline circulation

high precision constraints on timing of alpine warm periods during the middle to late pleistocene using speleothem growth periods a long standing problem in the reconstruction of warm climate periods during the late quaternary is the difficulty of determining absolute ages for undisturbed terrestrial climate archives speleothems offer an important source of information about the timing and duration of middle and late pleistocene warm phases a flowstone from the high elevation spannagel cave zillertal alps austria provides a new absolutely dated climate record which includes the most prominent warm phases between 260 and 50 ka before present new data from the penultimate interglacial improve our knowledge about the timing and progression of warm periods in the alps corresponding to marine isotope stages 7 and 8 speleothem growth phases were identified from 261 to 249 from 236 to 229 and from 200 to 192 ka an early onset of the last interglacial is corroborated by a growth phase commencing at 136 7f2 8 ka and the youngest section of the flowstone provides further evidence for an alpine climate during time intervals corresponding to marine isotope stages 5a and 3 sufficiently warm to allow speleothems to grow the high resolution stable isotope profile taken along the growth axis of the flowstone provides information about the hydrological conditions during the growth phases d 2005 elsevier b v all rights reserved

benthic foraminiferal and stable isotope evidence for a younger dryas style cold spell at the saalian eemian transition denmark abstract benthic foraminiferal and stable isotope studies of two borings from the island of anholt denmark reveal a continuous late saalian eemian sequence with an overall gradual warming interrupted by a short term temperature deterioration comparable with the younger dryas cold spell the sequence is correlated to the global deep sea stable isotope record based on environmental evidence given by foraminiferal faunas and stable isotopes the following environmental changes in the anholt cores can be attributed to the global variations 1 1 an interstadial phase the flakket interstadial which had a duration of about 1000 years is correlated to stable isotope event 6 01 2 2 the following cold spell the kattegat stadial spanning about 1000 years represents most of the interval between isotope events 6 01 and 6 0 3 3 a phase of rapid warming within about 1000 years bsotope events 6 0 and 5 53 4 4 a sea level change within the eemian between isotope events 5 53 and 5 51

suborbital climate variability during marine isotopic stage 5 in the central mediterranean basin evidence from calcareous plankton record abstract new faunal and floral records from ocean drilling project hole 963a resolved at 80 year spacing provide evidence of suborbital scale climate variability in the central mediterranean sea throughout marine isotope stage mis 5 cold events in the central mediterranean sea indicated by low abundances of warm species and high abundances of cold species are also evident in a planktonic foraminifera paleoclimatic curve they have been linked to ngrip greenland ice core c events and appear correlative with similar sub millennial climate fluctuations identified in the north atlantic region and in the alboran basin westernmost mediterranean low resolution benthic and planktonic oxygen isotope fluctuations parallel trends in the surface records evidenced by planktonic assemblage fluctuations bolstering their interpretation as climate proxies climate events also occur in the mediterranean between named c events and may be coeval with additional climate events identified recently in the western subtropical atlantic hence we propose that frequent climate oscillations during mis 5 characterize both sides of the mid latitude north atlantic perhaps indicating millennial scale variations in mid latitude atmospheric patterns

timing duration and transitions of the last interglacial asian monsoon thorium 230 ages and oxygen isotope ratios of stalagmites from dongge cave china characterize the asian monsoon and low latitude precipitation over the past 160 000 years numerous abrupt changes in 18o 16o values result from changes in tropical and subtropical precipitation driven by insolation and millennial scale circulation shifts the last interglacial monsoon lasted 9 7 1 1 thousand years beginning with an abrupt less than 200 years drop in 18o 16o values 129 3 0 9 thousand years ago and ending with an abrupt less than 300 years rise in 18o 16o values 119 6 0 6 thousand years ago the start coincides with insolation rise and measures of full interglacial conditions indicating that insolation triggered the final rise to full interglacial conditions

evolution and demise of the last interglacial warmth in the subpolar north atlantic detailed faunal isotopic and lithic marine records provide new insight into the stability and climate progression of the last interglacial period marine isotope stage mis 5 which peaked approximately 125 000 years ago in the eastern subpolar north atlantic at the latitude of ireland interglacial warmth of the ice volume minimum of substage 5e mis 5e lasted 10 000 years 10 ka and its demise occurred in two cooling steps the first cooling step marked the end of the climatic optimum which was 2 3 ka long minor ice rafting accompanied each cooling step the second larger step encompassing cold events c26 and c25 was previously identified in the northwestern atlantic approximately 41c of cooling occurred between peak interglacial warmth and c25 and the region experienced an additional temporary cooling of at least 1 21c during c24 a cooling event associated with widespread ice rafting in the north atlantic beginning with c24 mis 5 was characterized by oscillations of at least 1 21c superimposed on a generally cool baseline the results of this study imply that the marine climatic optimum of the last interglacial was shorter than previously thought the finding that the eastern subpolar north atlantic cooled significantly before c24 reconciles terrestrial evidence for progressive climate deterioration at similar and lower latitudes with marine conditions our results also demonstrate a close association between modest ice rafting cooling and deep ocean circulation even during the peak of mis 5e and in the earliest stages of ice growth

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