early pleistocene climate changes in the central mediterranean region as inferred from integrated pollen and planktonic foraminiferal stable isotope analyses vegetation inherited from a pliocene subtropical climate evolved through obliquity oscillations and global cooling leading to modern conditions an integrated highly time resolved record of pollen and stable isotopes 18o and 13c of globigerina bulloides was obtained to understand vegetation responses to early pleistocene climate changes continental and marine responses are compared in the central mediterranean region with a particular consideration of environmental changes during anoxic events pollen data illustrate vegetation dynamics as follows 1 development of mesothermic elements warm and humid conditions 2 expansion of mid and high altitude elements cooler but still humid conditions and 3 strengthening of steppe and herb elements cooler and dry conditions these successions correlate with precession 18o variations recorded by globigerina bulloides define two cycles mis 43 40 related to obliquity at northern low to mid latitudes the pollen signal records temperature and wetness changes related to precession even during global climate changes induced by obliquity this may result in unexpected increasing wetness during glacial periods which has to be considered specific to the central and eastern mediterranean region lastly an analysis of anoxic events reveals that enhanced runoff is indicated by increasing frequency of the riparian trees liquidambar and zelkova

summer air temperature reconstructions from the last glacial stage based on rodents from the site taillis des coteaux vienne western france the oxygen isotope composition of phosphate from tooth enamel of rodents 18op constitutes a valuable proxy to reconstruct past air temperatures in continental environments this method has been applied to rodent dental remains from three genera arvicola sp microtus sp and dicrostonyx sp coming from taillis des coteaux vienne france this archaeological site contains an exceptionally preserved sedimentary sequence spanning almost the whole upper palaeolithic including seven stratigraphic layers dated from 35 to 17 cal ka bp the abundant presence of rodent remains offers the opportunity to quantify the climatic fluctuations coeval of the various stages of human occupation of the site differences between 18op values of arvicola sp and microtus sp teeth are interpreted as the result of heterochrony in tooth formation as well as differences in ecology mean 18op values of microtus sp are preferentially used to reconstruct summer air temperatures which range from 16 0 3 7 to 19 1 3 1 c throughout the sedimentary sequence however the highest variability is observed during the last glacial maximum

distribution patterns of live planktic foraminifers as related to regional hydrography and productive systems of the mediterranean sea abstract distribution patterns of live planktic foraminifers are examined at two times of the year late summer and late winter through horizontal plankton towing along a nw se transect across the west and east mediterranean basins and in the alboran sea french oceanographic cruises vicomed i ii and iii respectively foraminiferal production is significantly different in the two sampling periods and across the west and east mediterranean foraminiferal density is higher in winter than summer e g in the western basin 3700 specimens 1000 m3 in winter against 200 600 specimens 1000 m3 in summer the production averaged for the two sampling sets is higher in the western basin than in the eastern one however in late summer peaks of maximal production are observed in the central mediterranean strait of sicily and ionian basin 1000 to 2000 specimens 1000 m3 where the assemblages are dominated by globigerinoides ruber rosea and g ruber alba in the mediterranean sea frontal regions and semipermanent eddies which are essentially controlled by regional hydrography represent a significant portion of the regional production they also elicit a higher diversity of species their influence is observed in summer as well as in winter at the end of summer the rather shallow mixed layer hosts spinose symbiont bearing species such as g ruber alba g ruber rosea o universa and g trilobus at that season in the western basin the nutrient content of the mixed layer is generally low and the surface layer is rapidly nutrient depleted summer foraminiferal production remains low at the surface with respect to the winter production in the eastern basin late summer and autumn correspond to the biological spring summer foraminiferal production in surface waters is higher than in winter but standing crops are lower than in the western basin for the same species at the same period in summer however frontal structures and eddies are generally better developed than in winter in some particular cases frontal boundaries in the western basin eddies south of cyprus nutrients from intermediate layers can be upwelled through isopycnal or diapycnal mixing to the photic zone and allow for secondary blooms in the western basin these blooms favour the development of grazers at depth globorotalia truncatulinoides g inflata south of cyprus in the eastern basin oligotrophic conditions promote the development of heterotrophic organisms and predatory foraminifers have higher standing stocks g ruber alba g ruber rosea in winter the break down of the thermocline combined with deep turbulent mixing in the northwestern basin and the deepening of the mixed layer in the alboran sea and along the north african coast result in increased phytoplankton biomass and favour reproduction and proliferation of species such as g truncatulinoides or g inflata our observations indicate that the geographic and depth distribution of live foraminiferal species cannot be entirely explained by the general temperature and salinity differences among the different mediterranean basins but that they are strongly related to regional hydrographic patterns hydrography controls the seasonality and depth of the turbulent mixing which differ between the western and the eastern basins the depth of the mixed layer and its seasonal stratification and the strength of the pycnocline nutrient supply and primary production are mostly regulated by these dynamics one may therefore expect that the species assemblages on the sea floor and in deep sea cores will also correlate to the various hydrographic parameters of the overlying water masses

organic rich layers in the metochia section gavdos greece evidence for a single mechanism of sapropel formation during the past 10 my abstract three well developed 10 ma old sapropels from the island of gavdos greece were selected for a detailed geochemical micropaleontological and sedimentological study the sapropels are characterized by a high organic carbon and a low carbonate content productivity was higher during sapropel formation as indicated by increased ba contents and higher percentages of the planktonic foraminiferal species neogloboquadrina acostaensis enrichment of mo and v in the sapropels indicates less oxygenated bottom water conditions which is supported by the flourishing of low oxygen tolerant benthic foraminifera variation in grainsize and the ti al ratio point to an alternating dominance of fluvial sapropels and eolian derived homogeneous intervals terrigenous clastics evidence for a local origin of the enhanced fluvial input comes from the gradual replacement of the sapropels by cyclic turbidite sequences which were fed by bed load type rivers the increased fluvial input during sapropel formation increased the sedimentation rate and caused the observed carbonate depletion the results obtained for the gavdos sapropels are consistent with those of previous studies of younger sapropels and related caco 3 cycles in the mediterranean the consistency in most of the geochemical and micropaleontological characteristics indicates that all sapropels and related layers are the result of a single mechanism for at least the past 10 my namely precession induced dry wet oscillations in the mediterranean climate still the effect of this mechanism on the intensity of surface water productivity dilution and diagenetic signals may differ from site to site depending on location depositional environment and intensity of the astronomical forcing

the obliquity controlled early pleistocene terrace sequence of the gediz river western turkey a revised correlation and chronology the buried early pleistocene river terrace record of the gediz river around kula western turkey has previously been considered to span the time interval equivalent to marine isotope stages mis 58 37 c 1 6 1 2 ma with the frequency of terrace formation mirroring obliquity driven climate change whereas progressive pleistocene incision of the gediz river is seen as a response to regional uplift the timing of fluvial incision leading to terrace formation and subsequent new floodplain development is believed to be climate controlled with incision deposition cycles resulting from varying sediment discharge conditions a direct consequence of changing climate and related vegetation change new outcrop observations downstream of the original field area alongside recently published geochronological data and improved understanding of the volcanic sequence all now suggest that the previously published interpretation is incorrect here we present a revised stratigraphy based upon terrace gradients of c 0 004 0 005 previously 0 001 in which 11 terraces are identified but only terraces gt11 the oldest to gt6 pre lava incursion predate volcanism the available geochronology suggests that terraces gt6 post first lava incursion to gt1 relate to the time interval mis38 28 c 1 26 1 ma however despite penecontemporaneous volcanism terrace formation continues to reflect sediment discharge changes predominantly controlled by regional climate change

reconstructing past planktic foraminiferal habitats using stable isotope data a case history for mediterranean sapropel s5 abstract a high resolution stable o and c isotope study is undertaken on all planktic foraminiferal species that are reasonably continuous through an eemian sapropel s5 from the western side of the eastern mediterranean the data are considered within a context of high resolution isotope records for two further s5 sapropels from the central and easternmost sectors of the basin alkenone based sea surface temperature records for all three sapropels and planktic foraminiferal abundance records for the same sample sets through all three sapropels results are compared with similar data for holocene sapropel s1 the adopted approach allows distinction between species that are most suitable to assess overall changes in the climatic hydrographic state of the basin including depth related differentiations and the main seasonal developments and species that are most affected by variable biological controls or local regional and transient physico chemical forcings it is found that a priori assumptions about certain species palaeohabitats based on modern habitat observations may become biased when non analogue conditions develop in the case of mediterranean sapropel s5 these consisted of enhanced freshwater dilution elevated productivity shoaling of the pycnocline between intermediate and surface waters and stagnation of the subsurface circulation under these conditions some species are found to shift into habitat settings that differ considerably from those occupied today the present multiple species approach can identify such anomalous responses and thus offers a sound background for further shell chemistry investigations and quantitative interpretation of the isotopic profiles we capitalise on the latter potential and offer the first quantitative estimates of monsoon flooding into the mediterranean during the deposition of eemian sapropel s5

african monsoon variability during the previous interglacial maximum abstract little is known about centennial to millennial scale climate variability during interglacial times other than the holocene we here present high resolution evidence from anoxic unbioturbated sediments in the eastern mediterranean sea that demonstrates a sustained 800 yr climate disturbance in the monsoonal latitudes during the eemian interglacial maximum 125 ka bp results imply that before and after this event the intertropical convergence zone itcz penetrated sufficiently beyond the central saharan watershed 21 n during the summer monsoon to fuel flooding into the mediterranean along the wider north african margin through fossil river wadi systems that to date have been considered only within a holocene context relaxation in the itcz penetration during the intra eemian event curtailed this flux but flow from the nile with its vast catchment area was not affected previous work suggests a concomitant eurasian cooling event with intensified impact of the higher latitude climate on the mediterranean basin the combined signals are very similar to those described for the holocene cooling event around 8 ka bp the apparent type of concurrent changes in the monsoon and higher latitude climate may reflect a fundamental mechanism for variability in the transfer of energy latent heat between the tropics and higher latitudes

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

extirpation of ophisaurus anguimorpha anguidae in western europe in the context of the disappearance of subtropical ecosystems at the early middle pleistocene transition abstract disarticulated remains of anguid lizards from the latest early pleistocene of the sierra de quibas abanilla murcia se spain are described and assigned to a new species ophisaurus manchenioi although ophisaurus is still extant in subtropical humid environments in north america northern africa and southeast asia the new species is the youngest known fossil representative of the genus in europe analysis of the palaeobiogeographic distribution of the genus reveals that its maximum extension occurred during the miocene followed by a north south withdrawal leading to its late pliocene restriction to the mediterranean area its european extirpation occurred at ca 1 2 0 9 ma after having survived in a few early pleistocene refugia on the southernmost iberian peninsula this extirpation is coeval with the early middle pleistocene transition an episode of major climatic change related to the intensification of northern hemisphere glaciation between 1 4 and 0 7 ma and which led to the disappearance of the subtropical humid forest biome at around 1 2 ma based on its latitudinal withdrawal temperature is inferred to have been an important limiting factor for the distribution of the genus ophisaurus however as the climate seems never to have been very cold on the southernmost iberian peninsula increasing aridity or habitat fragmentation linked to such increasing aridity may have also played a role in the extirpation of the genus ophisaurus from western europe during the early middle pleistocene transition

the evolution of pleistocene climate a time series approach abstract in the later part of the pleistocene variations in global ice volume have been dominated by an approximate 100 000 year cycle analysis of 2 myr long oxygen isotope record from an equatorial pacific core indicates that this is true only for the last 900 000 years prior to this time the amplitude of the 100 000 year cycle is much reduced as is the variance of all oscillations with periods greater than 60 000 years based on results of time series analysis of this 2 myr long record the pleistocene glacial cycles can be divided into three sections 1 the late pleistocene 0 900 kyr b p where the variations in the isotope record are dominated by the 100 000 year cycle 2 the middle pleistocene 900 1450 kyr b p in which low frequency components are not as important as in the later period of the pleistocene and 3 the early pleistocene late pliocene 1450 2000 kyr b p where general reductions of importance at all frequencies is seen as compared to the later intervals recent modeling efforts which describe variations in global ice volume show that the dominant low frequency component observed in the late pleistocene can result from different time constants for the rate of glacial growth and decay in response to variations in the earth s orbital parameters it is hypothesized that during the early pleistocene the rate of growth and decay of glaciers were more similar and that continental erosion by successive glacial advances lowered the land surface in areas of ice cap formation to below sea level when the ice caps became marine based more rapid decay of the ice became possible

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

frequency characteristics of the response of water pressure in a closed well to volumetric strain in the high frequency domain 1 oscillations of water pressures and crustal strains due to the seismic waves of the 2010 chile earthquake were observed in japan the oscillations of water pressures observed over the frequency range of 0 002 to 0 1 hz were negative proportional to the oscillations of volumetric strains the responses of water pressures in closed wells are frequency dependent the expression for the response of water pressure in a closed well to crustal strain is developed based on the poroelastic theory the expression developed in the present paper describes the frequency characteristics of the responses the response is useful for the estimation of rock properties in addition the responses of water pressure due to tidal volumetric strain are estimated and compared with the responses due to the seismic waves

orbital insolation ice volume and greenhouse gases abstract the specmap models of orbital scale climate change imbrie et al paleoceanography 7 1992 701 paleoceanography 8 1993 699 are the most comprehensive to date all major climatic observations were analyzed within the framework of the three orbital signals subsequently tuning of signals in vostok ice to insolation forcing has fixed the timing of greenhouse gas changes closely enough to permit an assessment of their orbital scale climatic role in addition evidence from several sources has suggested changes in the specmap 18 o time scale this new information indicates that the timing of co 2 changes at the periods of precession and obliquity does not fit the 1992 specmap model of a train of responses initiated in the north propagated to the south and later returning north to force the ice sheets in addition analysis of the effects of rectification on 100 000 year climatic signals reveals that all have a phase on or near that of eccentricity this close clustering of phases rules out the long time constants for 100 000 year ice sheets required by the 1993 specmap model a new hypotheses presented here revives elements of an earlier climap view hays et al science 194 1976a 1121 but adds a new assessment of the role of greenhouse gases as proposed by milankovitch summer mid july insolation forces northern hemisphere ice sheets at the obliquity and precession periods with an ice time constant derived here of 10 000 years changes in ice volume at 41 000 years drive ice proximal signals sst nadw dust that produce a strong positive co 2 feedback and further amplify ice volume changes at the precession period july insolation forces ice sheets but it also drives fast and early responses in ch 4 through changes in tropical monsoons and boreal wetlands and variations in co 2 through southern hemisphere processes these ch 4 and co 2 responses enhance insolation forcing of ice volume climatic responses at 100 000 years result from eccentricity pacing of forced processes embedded in obliquity and precession cycles increased modulation of precession by eccentricity every 100 000 years produces 23 000 year co 2 and ch 4 maxima that enhance ablation caused by summer insolation and drive climate deeper into an interglacial state when eccentricity modulation decreases at the 100 000 year cycle ice sheets grow larger in response to obliquity forcing and activate a 41 000 year co 2 feedback that drives climate deeper into a glacial state alternation of these forced processes because of eccentricity pacing produces the 100 000 year cycle the 100 000 year cycle began 0 9 myr ago because gradual global cooling allowed ice sheets to survive during weak precession insolation maxima and grow large enough during 41 000 year ice volume maxima to generate strong positive co 2 feedback the natural orbital scale timing of these processes indicates that ice sheets should have appeared 6000 3500 years ago and that co 2 and ch 4 concentrations should have fallen steadily from 11 000 years ago until now but new ice did not appear and co 2 and ch 4 began anomalous increases at 8000 and 5000 years ago respectively human generation of co 2 and ch 4 is implicated in these anomalous trends and in the failure of ice sheets to appear in canada

pliocene and lower pleistocene vegetation and climate changes at the european scale long pollen records and climatostratigraphy the biostratigraphically calibrated long pollen record at dsdp site 380 southwestern black sea displays a high resolution continuous and contrasted evolution of the vegetation in the region for the entire pliocene and lower pleistocene an accurate correlation is established with the reference global oxygen isotopic curve and with the northwestern european climatostratigraphy climatostratigraphic relationships are evident at the latitudinal and longitudinal scale of europe confirming the extensive strength of pollen analysis as a tool for correlations over large distances

an onshore bathyal record of tectonics and climate cycles at the onset of the early middle pleistocene transition in the eastern mediterranean early pleistocene calabrian clays of the lindos bay formation have been uplifted and are exposed today on the eastern coast of rhodes hellenic forearc greece the hemipelagic origin of these sediments and the excellent preservation of the microfossils they contain make the lindos bay formation a unique element in the eastern mediterranean which has the potential to constitute a paleoclimate referential framework of the region for the early middle pleistocene transition empt in this context 98 samples were collected in the type locality section of the lindos bay formation stable isotope 18o 13c analyses were carried out on benthic uvigerina peregrina and planktonic globigerina bulloides foraminifera for the interval between 1100 ka and 858 ka we identify and continuously reconstruct the climate cycles that occurred between marine isotope stages mis 32 and 21 counts of planktonic foraminifera were further carried out and allow connecting the conditions occurring locally in the surface waters with the glacial interglacial cycles during the onset of the empt while sub tropical taxa dominate the assemblages glacials were associated with short term 10 kyr influxes of temperate to subpolar species suggesting cooling and or increasing productivity in the surface waters correlating with the deposition of sapropels in the eastern mediterranean deep sea finally planktonic benthic foraminiferal ratios show that the section deposited at upper bathyal depths between 450 m and 150 m during the late early pleistocene the eastern coast of rhodes has locally undergone repeated transient and possibly very rapid vertical motions which are overprinted on a regional tectonically forced regressive trend

ungulate carrying capacity in pleistocene mediterranean ecosystems evidence from the atapuerca sites abstract large herbivore carrying capacity that is the maximum biomass of large herbivorous mammals that an ecosystem is able to sustain for the long term is a key factor in ecosystems trophic dynamics the carrying capacity of pleistocene ecosystems conditioned the survival opportunities and colonization capabilities of hominin populations in europe in this study we use the amphibian and squamate record of two early and middle pleistocene sites from sierra de atapuerca spain to obtain estimates of past temperature and rainfall values a function derived from the analysis of a wide set of recent mammalian communities is used to infer the large herbivore carrying capacity of the atapuerca ecosystems during the pleistocene from those climatic variables this function provides reliable estimates of large herbivore carrying capacity in open environments but not in forest communities the results presented in this study indicate that carrying capacity was higher at atapuerca during most of the sequence than in the present our data also suggest that in most mediterranean ecosystems large herbivore biomass is currently below the carrying capacity of the environment due to the relatively low diversity of the large herbivore guild in most recent communities although the carrying capacity was high at atapuerca in the periods the area was occupied by humans it was also high in other periods for which no evidence of human presence has been recorded thus the relationship between human occupation of the territory and carrying capacity does not appear to be simple

vegetation change in a climatic cycle of early pleistocene age in the leffe basin northern italy abstract the plio pleistocene deposits of the leffe basin in the lombardian pre alps in italy first investigated in quarry and lignite mine shafts by lona in 1950 were recently cored the pollen record of part of this core reveals a sequence of four climatic cycles one of them which is about 1 6 ma old and particularly characteristic is discussed here a long interglacial stage can be identified by the dominance of pollen of deciduous trees of temperate climate it clearly shows a forest succession of a mixed oak forest of dry temperate climate followed by a strong development of a juglandaceae assemblage rich in arcto tertiary elements some of them indicating a wet climate in particular the carya peaks appear to be linked to a warm temperate 14 16 c mean annual temperature humid maritime climate with a long growth season if we compare them with modern and fossil analogs this stage is followed by a cooling leading to a long phase of wet coniferous forest this forest succession is subsequently interrupted by a brief period of open vegetation indicating a drier and colder continental climate followed by a new vegetational cycle the climate evolution is discussed in comparison with other recent pollen successions of uppermost pliocene age in the mediterranean area the cycle described is estimated to have lasted about 30 ka the entire leffe lacustrine succession records eight climatic cycles of moderate amplitude we suggest that this cyclicity has been induced by obliquity forcing correlation of the cold phases with the major glacial events of the southern alps as proposed by venzo 1950 and lona 1950 is excluded

a late early pleistocene pollen record from fontana ranuccio central italy a pollen record from a sediment core drilled underneath the acheulian site of fontana ranuccio provides new data on the vegetation characters in central italy during the late early pleistocene in a forest phase possibly corresponding to a substage of marine isotope stage 21 a number of tree taxa nowadays extinct in europe cathaya tsuga taxodium type carya and pterocarya are present at fontana ranuccio in a temperate phase characterised by dense forest conditions dominated by alnus and pterocarya the comparison of the fontana ranuccio record with other dated sites distributed along the italian peninsula indicates that the floristic and vegetational characters of the mid pleistocene revolution present a rather distinct succession of biostratigraphic events compared to other early pleistocene pollen records from southern europe the italian peninsula shows greater floristic similarities with the eastern mediterranean regions than with the iberian peninsula copyright 2011 john wiley sons ltd

a synthetic pollen record of the eastern mediterranean sapropels of the last 1 ma implications for the time scale and formation of sapropels abstract the quaternary climate of southern europe south italy and greece is investigated by pollen analysis of the sapropels which were deposited in the deep eastern mediterranean sea during the last 1 million year ma the time scale of core kc01b in the ionian sea has been established by tuning its oxygen isotopic record to the ice volume model of imbrie and imbrie 1980 for the last 250 000 year 250 ka the previous pollen studies and astronomical tuning have been confirmed sapropels were deposited under a large range of mediterranean climates fully interglacial fully glacial and intermediary as revealed mainly by the balance between the respective pollen abundances of oak quercus and sage brush artemisia the high value of the oak reveals the warm and wet climate of an interglacial and the high value of the sage brush the dry and cold climate of a glacial whereas the mediterranean climate is directly related to the variation of the high latitude ice sheets the deposition of sapropels is not so in contrast with the wide climatic range sapropels were deposited only when summer insolation in the low latitudes reached its highest peaks however between 250 ka and 1 ma that stable pattern is not yet established only six sapropels are observed many expected ones do not appear even as ghosts signalled by peaks of barium abundance that remain after the post deposition oxidation of organic matter the pattern of sapropel formation in stable and direct relationship to highest insolation does not seem to apply for five of those sapropels neither climate extremes are observed they mainly formed during intermediary types of mediterranean climate in contrast one sapropel and one ghost relates to a relatively low peak of insolation and its climate is of a unique composite type not seen later this might suggest an unsuspected more complex pattern linking the formation of mediterranean sapropels to the astronomical configuration

the isotopic signature of planktonic foraminifera from ne atlantic surface sediments implications for the reconstruction of past oceanic conditions the stable isotope compositions of the planktonic foraminifera globigerina bulloides globigerinoides ruber white and pink varieties globigerinoides trilobus globorotalia inflata and globorotalia truncatulinoides right and left coiling types were examined as recorders of north atlantic surface water properties based on 40 box core surface sediments between 60 and 30 n while g ruber white and pink varieties and g trilobus mainly reflect summer surface water conditions in their oxygen isotope composition g bulloides reflects temperatures of the northward migrating spring bloom february march in the south to may june in the north our data show that g bulloides cannot be regarded as an indicator for summer temperatures as deduced from duplessy et al s data gt inflata and gt truncatulinoides right and left coiling build their shells in the coldest waters compared with the other species and reflect temperatures between 100 and 400 m water depth the difference in oxygen isotope composition between g bulloides and g inflata serves as a proxy for water mass stratification g bulloides is the only species that gives a distinct pattern in its carbon isotopic composition showing a high correlation with the surface water phosphate values along the transect and may serve as a proxy for palaeonutrients and or productivity

early pleistocene climate cycles in continental deposits of the lesser caucasus of armenia inferred from palynology magnetostratigraphy and 40ar 39ar dating plio pleistocene diatomitic sequences in the shamb paleo lake south armenia lesser caucasus offer a rare opportunity to give new insights on the paleo climate of western asia we present an integrated palynological 40ar 39ar geochronologic and magnetostratigraphic study for the most complete section in the sedimentary deposits of the shamb paleo lake 40ar 39ar dating of two volcaniclastic layers provided ages of 1 24 0 03 and 1 16 0 02 ma 2 magnetostratigraphic data show that the entire shamb section is of reversed polarity which combined with 40ar 39ar dating suggests that the entire section correlates with part of the matuyama period 1 785 1 070 ma pollen assemblages and macroremains diversity clearly show an alternation of glacial and interglacial phases age calibrations and accumulation rate extrapolation allow a direct correlation of climate changes with the global isotopic curve and show that the shamb section probably ranges from approximately 1 300 to 1 080 ma marine isotopic stages 40 to 31 the vegetation of the lesser caucasus developed in a mosaic pattern in a pleistocene continental mostly arid climate comparable to the present day climate the observed vegetation changes record a dominant climate response to the obliquity orbital parameter but the influence of precession could not be established from the shamb data pollen and macroflora both indicate that glacial periods were cold and dry and that interglacials were warm with local humidity the early pleistocene climatic model for western asia is thus similar to the climatic model for the mediterranean area

late miocene to plio pleistocene fluvio lacustrine system in the karacasu basin sw anatolia turkey depositional paleogeographic and paleoclimatic implications abstract the sedimentary record of the late cenozoic karacasu basin a long lived continental half graben from southwestern turkey is characterized by siliciclastic and carbonate deposits sedimentation was controlled by an active nw se trending major normal fault along the basin s southern margin and by climatically induced lake level changes detailed facies analysis subdivides the entire neogene quaternary basin fill into three distinct litostratigraphic units representing paleogeographic changes and sedimentation patterns throughout the basin evolution sedimentation commenced in the late miocene with the deposition of proximal medial alluvial fan and fluvial facies damdere formation fa1 at this stage alluvial fans developed in elevated areas to the south prograding towards the basin center at the beginning of the pliocene fresh to slightly alkaline shallow lake deposits fa2a of the karacaoren formation formed the lake became open and meromictic conditions developed fa2b pollen data from the fa2b facies show that climate was arid to humid climate probably changed cyclically through time producing alternation of artemisia steppe cold and dry periods and more forested vegetation warm and wet the open lake facies passes upwards into lake margin facies fa2c but it was still dominated by alkaline to slightly saline lake conditions sedimentation was almost continuous from the late miocene to pleistocene in the early quaternary the basin was dissected by the re activation of basin bounding faults the unconformable base of the overlying quaternary deposits karacasu formation fa3 reflected the basin s transformation from a half graben into a full graben system oxygen isotope data from carbonates show an alternation of humid climatic periods when freshwater settings predominated and semiarid arid periods in which the basin hosted alkaline and saline water lakes neotectonic activity has rejuvenated many of the basin bounding faults causing development of talus aprons and local alluvial fans the basin was progressively incised by modern rivers that have largely smoothed out the topographic relief of the graben margins

mid pleistocene revolution and the eccentricity myth the mid pleistocene revolution mpr is the term used to describe the transition between 41 ka and 100 ka glacial interglacial cycles which occurred about one million years ago despite eccentricity having by far the weakest influence on insolation received at the earth s surface of any of the orbital parameters it is often assumed to be the primary driver of the post mpr 100 ka climate cycles the traditional solution to this is to call for a highly nonlinear response by the global climate system to eccentricity this eccentricity myth is a simplified view of the relationship between global climate and orbital forcing and is in part due to an artefact of spectral analysis our aim here is to clarify the often confused role of eccentricity and review current theories of the mpr we suggest that the post mpr 100 ka glacial interglacial cycles are more closely linked to precession with the saw toothed climate cycles being defined by every four or five precessional cycle because control over the number of precessional cycles involved is determined by eccentricity eccentricity at most paces rather than drives the system if true then one must also question whether the mpr itself defined by an abrupt change in spectral characteristics is not also somewhat misconceived

a low seasonality scenario in the mediterranean sea during the calabrian early pleistocene inferred from fossil arctica islandica shells understanding past seasonal temperature variability in the ocean is essential to evaluate the effects of future climate change on marine ecosystems here we estimate seasonal water temperature amplitudes from stable oxygen isotope 18oshell values of fossil shells of arctica islandica assuming 18owater 0 9 0 1 v smow specimens were collected from three pleistocene successions emilian and sicilian substages of the calabrian in central and southern italy i e rome lecce and sicily biostratigraphic analyses from rome quarry deposits indicate an age between 1 6 and 1 2 ma whereas sicily and lecce successions are slightly more recent between 1 1 and 0 62 ma prior to carbonate geochemical analysis we checked the shells for potential diagenetic alterations e g from aragonite to calcite using confocal raman microscopy 18oshell transects indicate an annual temperature amplitude of about 3 c during the early pleistocene this is in sharp contrast to reconstructions based on faunal assemblages according to which the simultaneous occurrence of boreal and warm water species in the calabrian mediterranean sea suggests a much higher seasonality ca 10 c the low seasonality and the relatively cold water 9 10 c indicate the outcrops represent colder climatic conditions compared to modern times and suggest the occurrence of a maximum glacial phase

vegetation response to obliquity and precession forcing during the mid pleistocene transition in western mediterranean region odp site 976 abstract the odp leg 161 site 976 alboran sea is a deep sea section sampled at a water depth of 1108 m in the western mediterranean sea pollen analysis provides a vegetation and climate record of the mid pleistocene transition mpt roughly one million years ago the age model tied to biostratigraphic events was revised by aligning the pollen climate index pci to mediterranean kc01b and global lr04 oxygen isotope records the studied time slice spans the interval 1 09 ma mis 31 to 0 90 ma mis 23 across this interval past phytogeography of nowadays extinct taxa which were rare allows a successful application of the modern analogues technique mat to quantitative climate reconstructions for the mpt five long term obliquity related vegetation successions o1 to o5 and eight short term precession related vegetation successions p1 to p8 are observed within the studied interval these vegetation successions regardless of their duration show the same pattern the progressive replacement of temperate trees by mountainous taxa and then by herbs and steppe maxima precession related successions correspond therefore to as dramatic vegetation changes as those driven by obliquity including a final steppe phase under deteriorated climate conditions wavelet analysis of the pci record shows that the western mediterranean experienced a shift at 1 01 ma from precession dominated frequencies 1 05 1 01 ma to obliquity dominated frequencies 1 01 0 9 ma there is therefore an apparent discrepancy between wavelet analysis results and vegetation dynamic analysis which suggests that obliquity and precession are recorded throughout the entire studied interval this discrepancy could result from the fact that the pci record sums somehow similar vegetation changes wet to dry occurring at different periodicities such a complex vegetation dynamics is mathematically rendered through a single parameter i e principal component which does not successfully catch the subtle combinations of variability occurring at two close periodicities furthermore the pollen inferred early pleistocene vegetation dynamic and climate of the western mediterranean region does not show a decrease of the obliquity response relative to the precession response at the onset of the mpt

an early pleistocene interglacial record from an intermontane basin of central italy scoppito l aquila abstract interdisciplinary investigations in the early pleistocene site of madonna della strada near scoppito l aquila central italy are presented complementing the information on large mammal remains recovered in the 1950s mammuthus meridionalis rhinoceros hippopotamus suid and small deer new fragmentary remains of an old rhinoceros individual are examined and discussed pollen analysis documents an interglacial forest phase with considerable frequencies of taxa presently extinct in the italian peninsula tsuga carya pterocarya and zelkova starting with an expansion of conifers progressively replaced by a mixed deciduous forest followed by an increase of mediterranean vegetation the abundance of extinct elements suggests an early pleistocene age older than the jaramillo subchron 1 07 ma the scarcity of picea and cedrus and the absence of liquidambar suggest that the record should be younger than mis 40 approx 1 3 ma this chronological setting indicates that hippopotamus antiquus was already present in italy before the jaramillo palaeomagnetic inversion

continuous pollen diagrams for the last 3 5 m y from israel vegetation climate and correlation with the oxygen isotope record abstract several continuous pollen diagrams have been obtained from boreholes penetrating the entire quaternary sequences of the hula and dead sea lakes in the jordan rift valley israel the dead sea served as a terminal base level through this period thus ensuring a complete continuous deposition volcanic intercalations within the hula lake sediments permit some control of the absolute datings a paleoclimatic model for the last 150 k y based on better dated sequences serves as a basis for correlating the israeli sections with the oxygen isotope records known from the oceans and the mediterranean the glacial phases are manifested in israel by periods of somewhat lower temperatures and higher rainfall some in summertime the interglacials are hot and dry with saharan conditions prevailing the interstadials are of the present day character of a short rainy winter and a dry hot long summer the first major cooling of the quaternary in israel took place some 2 4 2 6 m y ago followed by a series of alternating wetter and drier phases corresponding quite well to changes in the global ice volume expressed by the oxygen isotope curves it seems however that some successions of the glacial phases are grouped in israel into longer wetter periods with the interglacials manifested as interstadials a similar case is seen for some of the interglacials successions with glacial phases as interstadials a possible explanation for the difference between the continental and the ocean records may lie in the distribution of the global ice volume differences in the accumulations of ice at the arctic and antarctic regions during some of the glacial phases could explain the extent of a glacial period on land while not being apparent from the oxygen isotope records and vice versa for the interglacials thus a well developed ice cap on antarctica may cause only a minor glaciation in the northern hemisphere but be recorded as a full glacial in the oceans

climatic patterns revealed by pollen and oxygen isotope records across the matuyama brunhes boundary in the central mediterranean southern italy a c 50 m thick section located in the crotone basin southern italy was investigated using oxygen isotopes pollen and planktonic foraminifera the section records two complete trans gressive regressive cycles mainly driven by glacio eustasy biostratigraphy and oxygen isotope chronology indicate that the section spans from marine isotope stage mis 22 c 0 87 ma to mis 18 3 c 0 73 ma thus straddling the matuyama brunhes m b boundary which occurs in the middle of mis 19 the rich pollen assemblages provide a unique record of the vegetation in the central mediterranean during the early middle pleistocene climatic transition interglacials are characterized by a mesothermic vegetation similar to the present day whereas a rain demanding conifer forest dominates the glacials of mis 20 and mis 18 this is unexpected because it is gener ally considered that during the pleistocene glacials in central mediterranean were characterized by steppe arid conditions by contrast arid conditions occur during the deglaciations these results are inconsistent with the widespread practice of linking glacials with arid conditions in the central mediterranean during pliocene and early pleistocene times this study emphasizes the need to establish more accurate land sea correlation

are the 41 kyr glacial oscillations a linear response to milankovitch forcing abstract the characteristics of glacial oscillations changed drastically 0 8 ma ago at the mid pleistocene transition during the past 0 8 ma the 100 kyr glacial interglacial oscillations were strongly asymmetric i e long glacial intervals of growth followed by rapid intervals of deglaciation the 40 kyr oscillations prior to the mid pleistocene transition were of a smaller amplitude and less asymmetrical looking the smaller amplitude apparently symmetric form and period that matches that of obliquity suggests that these oscillations were a linear response to milankovitch forcing while the 100 kyr oscillations are attributed either to some nonlinear self sustained variability due to a mechanism internal to the climate system itself or to nonlinear amplification of the insolation forcing the significant strengthening of the 100 kyr eccentricity power in the past 800 kyr is one of the intriguing questions of climate history here we show that glacial interglacial oscillations pre mid pleistocene transition are in fact significantly asymmetric this asymmetry may contradict a straight forward linear milankovitch explanation and we therefore suggest that the glacial oscillations before and after the transition may both be explained as self sustained variability although the possibility of nonlinear response to insolation forcing still exists the role of milankovitch forcing is in setting the phase of the oscillations e g time of terminations and their period rather in being the main driving force of the oscillations this is demonstrated using a simple model based on the sea ice switch mechanism of gildor and tziperman paleoceanography 15 2000 605

recent sedimentary events in the western gulf of lions western mediterranean abstract analysis of very high resolution data 3 5 khz profiles and em12d acoustic imagery collected during the calmar catalono languedocian margin cruise 1997 highlighted the occurrence of two very recent but previously unknown erosional sedimentary events on the continental rise between the rhone fan and the pyreneo languedocian ridge these events preserved as unconformable very thin lobes observable on acoustic imagery but not on 3 5 khz echo soundings relate to erosional processes linked to near bottom currents that seem to characterize the holocene hydrodynamical conditions in the deep gulf of lions they follow a pleistocene regime when gravity sedimentation dominated on the gulf of lions margin either through aggradational turbidite deposition rhone fan and pyreneo languedocian ridge or through remobilization of sediments by regional mass movements processes

palynological evidence for the astronomical origin of lignite detritus sequence in the middle pleistocene marathousa member megalopolis sw greece the marathousa member middle pleistocene strata in the fluvio lacustrine megalopolis basin southwest greece displays distinct but complicated lithological cycles comprising first order alternation of lignites and detrital muds and second order alternation expressed by frequent intercalation of organic layers palynological evidence indicates that the lithological cycles are driven by the earth s orbital forcing all the lignite seams yield temperate oak forest whereas the detrital beds provide semi arid steppe mainly of artemisia this means that the first order lithological cycle represents the glacial interglacial cycle i e the 100 kyr eccentricity cycle providing a timescale of at least 350 kyr to the marathousa member pollen also detects smaller scale climate fluctuations in many of the subordinate organic layers with the total number of fluctuations being five in a complete lignite detritus couplet this means that the second order lithological cycle reflects the 21 kyr insolation cycle a tentative phase relation between the lithological cycles and the astronomical cycles is shown based on palynostratigraphy and electron spin resonance dating lacustrine environments with increased water tables are implied for the glacial periods sedimentologically in contrast to local swamp vegetation for the interglacial periods the subordinate organic layers were formed under intermediate environments climate water depth etc between full glacials and interglacials 2002 elsevier science b v all rights reserved

seven ambiguities in the mediterranean palaeoenvironmental narrative abstract a review of seven outstanding issues on mediterranean palaeoenvironments is presented these are related to the dominant orbital pacing of climate variability the length of the interglacial vegetation succession the influence of the african summer monsoon the seasonality of precipitation during boreal insolation maxima the moisture balance during glacial maxima and the appearance of the mediterranean type climate rhythm and evolution of mediterranean sclerophyllous plants what emerges is that 1 marine 18oplanktonic and sst records show that precession has been a fundamental tempo of mediterranean climate change representing both a low latitude signal runoff from north africa and the direct influence of insolation at mediterranean latitudes but high latitude glacial effects 41 kyr and 100 kyr cycles became superimposed after 2 8 ma sapropel and dust deposition patterns in marine cores reveal that obliquity also has an effect on mediterranean climate through dry wet oscillations which are independent of glacial interglacial variability 2 the temperate part of interglacial vegetation succession has a duration of approximately half a precession cycle this persisted during the interval of obliquity dominated glacial cycles 2 8 1 ma with distinct forest successions following the precessional cycles however these are not always separated by an open vegetation phase because of minimal ice growth producing an impression of a prolonged interglacial forest interval 3 the effect of an enhanced african monsoon during summer insolation maxima has been mainly indirect in terms of nile discharge and runoff along the north african coast leading to increased freshwater input into the mediterranean sea reduced deep water ventilation and sapropel deposition 4 the notion of an accentuated summer rain regime in the northern mediterranean borderlands also contributing to a freshening of the mediterranean sea during boreal insolation maxima is not supported by the available evidence which suggests increased summer aridity 5 recent improvements in chronological precision and data resolution point to an increase in aridity and decreased temperatures during the last glacial maximum 21 2 ka but suggest an increase in effective moisture during the immediately preceding interval of 24 27 ka 6 the mediterranean type climate is not exclusively a post 3 6 ma phenomenon but may have appeared intermittently during the course of the tertiary or before 7 if that is the case then the paradigm that the sclerophyllous evergreen habit represents a pre adaptation to summer drought may need re evaluation

vegetation changes during the late early pleistocene at montalbano jonico province of matera southern italy based on pollen analysis pollen analysis of the early pleistocene montalbano jonico section in southern italy reveals cyclic changes driven by climate and eustasy as illustrated by mesothermic vs steppe elements for climate and pinus vs caryophyllaceae amaranthaceae chenopodiaceae and ephedra for eustasy these results are directly compared with oxygen isotope data on globigerina bulloides constrained within a biostratigraphic framework based on nannofossils and foraminifers facilitating a new age calibration for the section marine isotopic stages 37 to 23 1 250 0 900 ma are recorded and compared with global and mediterranean oxygen isotope curves high frequency changes in pollen are related to the mediterranean curve globigerinoides ruber from odp site 967 and superimposed the lr04 stack curve during the early pleistocene pollen recorded global and regional climate changes related to obliquity and precession respectively and regional tectonic evolution precession forcing was caused by mediterranean wetness related to precession the intensified precession effect over climatic cycles that is expected during the middle pleistocene transition is not recorded in the montalbano jonico interval a vegetation changes

the reunion subchron vegetation and climate history of the northeastern russian arctic inferred from the lake el gygytgyn pollen record abstract the 318 m thick sediment record from lake el gygytgyn provides unique opportunities for a detailed examination of environmental changes during the reunion subchron polarity reversal event 2 1384 2 1216 myr bp in the northeastern russian arctic the paper describes vegetation and climate fluctuations between 2 15 and 2 10 myr bp as inferred from palynological data biome reconstructions indicate that throughout this interval the tundra tund biome generally has higher affinity scores as compared to cold steppe step or cold deciduous forest clde an exception is the climatic optimum between 2 139 and 2 131 myr bp coinciding with marine isotope stage 81 approximately the reunion subchron when the clde biome has the highest scores landscape openness indices suggest that more closed vegetation characterized most of the interval between 2 146 and 2 127 myr bp when deciduous forest and shrubs expanded in the regional vegetation and climate was relatively warm and wet peaks in green algal colonies botryococcus and zygnema type spores 2 150 2 146 2 131 2 123 and 2 112 2 102 myr bp indicate expansions of shallow water habitats and lowered lake levels comparisons with biome reconstructions from other interglacial intervals at lake el gygytgyn suggest that precession related summer insolation intensity and obliquity related duration of summer daylight are major controls on the onset of interglaciations whereas obliquity probably plays a more significant role on vegetation succession at northern high latitudes during the pleistocene

exploring the structure of the mid pleistocene revolution with advanced methods of time series analysis the mid pleistocene climate transition is a complex global change leading to late pleistocene ice ages with increased mean ice volume and dominant 100 ka cycle a thorough understanding of this transition demands quantitative investigations in the time and frequency domains and in the stochastic domain three methods of time series analysis are presented which have been adapted for this purpose they are tested by means of predefined artificial time series and applied to benthic oxygen isotope d18o records which serve as ice volume indicator results are as follows a the time dependent mean shows an increase of 0 35 vs pdb from 942 to 892 ka b evolutionary spectral analysis reveals an abrupt in crease of 100 ka cycle amplitude at approximately 650 ka c probability density function exhibits a bifur cation behavior at approximately 725 ka these find ings point to a multiple transition from a more linear climate system to a strong nonlinear system the signif icant lead of the transition in mean in relation to the 100 ka amplitude change and bifurcation is left open for explanation

a long early pleistocene pollen record from baza basin se spain major contributions to the palaeoclimate and palaeovegetation of southern europe abstract the basin of baza is located in the central area of the betic range se spain with a catchment area of over 4000 km2 it contains a continuous and well preserved lacustrine sedimentary record from the late miocene to the middle pleistocene the basin encloses numerous miocene to pleistocene mammal fossil sites that include some of the oldest hominin occurrences in western europe found at the orce sites the present work features the palynological analysis of sediment samples obtained from the palominas drill core the palominas core cuts thorough fine grained sedimentary units located in the depocenter of the basin which contain well preserved pollen grains the palynoflora found in the core is rich in herbaceous pollen as well as quercus and pinus with other tree taxa appearing in lesser quantities spectral analysis reveals strong climatically controlled vegetation successions the application of the biomization method on these assemblages allows for a reconstruction of the biome succession the early pleistocene landscape was dominated by a sequence of steppe evergreen bushland and mixed forest biomes the coexistence approach method shows that se spain experienced humid periods during which precipitations were significantly higher than during the modern climate these humid phases are correlated with warm interglacial periods which featured the development of open forests dryer phases and fully open environments are correlated with colder glacial periods based on the palynoflora a calabrian age is suggested for the palominas core the flora and climatic patterns identified in baza are similar to the ones identified in calabrian records of southern italy and greece

late pliocene northern hemisphere glaciations the continental and marine responses in the central mediterranean abstract detailed pollen analyses and oxygen isotope records of three foraminiferal species globigerina bulloides uvigerina peregrina and cibicides pachyderma from the semaforo and vrica composite sections crotone southern italy have been compared to the global climatic changes depicted by late pliocene early pleistocene foraminiferal 18o records of site 607 in the north atlantic and hole 653a in the tyrrhenian basin west mediterranean major overturns in the mid altitude vegetation are shown near isotopic stages 82 60 58 and 50 at about 2 03 ma 1 6 ma and 1 37 ma according to the raymo et al 1989 and ruddiman et al 1989 timescales at the same dates glacial 18o maxima either became higher or display step increases in the western mediterranean or in the open ocean as well this suggests that size increases of northern hemisphere ice sheets were the driving factor for regional or local marine and continental environmental changes within the mediterranean basin near isotopic stages 62 60 close to the conventional plio pleistocene boundary the climatic conditions severed enough within the mediterranean basin to modify the continental environment as depicted by a sudden increase of artemisia percentages while the first significant southward migration of the north polar front may have been recorded by an influx of left coiling neogloboquadrina pachyderma in the central mediterranean it also appears that boreal guests entered the mediterranean during phases of 18o enrichment of foraminiferal calcite there does not seem to be any discrepancy between the climatic concept of the pliocene pleistocene boundary and its chronostratigraphic definition

unexpected weak seasonal climate in the western mediterranean region during mis 31 a high insolation forced interglacial marine isotope stage 31 mis 31 is an important analogue for ongoing and projected global warming yet key questions remain about the regional signature of its extreme orbital forcing and intra interglacial variability based on a new direct land sea comparison in sw iberian margin iodp site u1385 we examine the climatic variability between 1100 and 1050 ka including the super interglacial mis 31 a period dominated by the 41 ky obliquity periodicity pollen and biomarker analyses at centennial scale resolution provide new insights into the regional vegetation precipitation regime and atmospheric and oceanic temperature variability on orbital and suborbital timescales our study reveals that atmospheric and sst warmth during mis 31 was not exceptional in this region highly sensitive to precession unexpectedly this warm stage stands out as a prolonged interval of a temperate and humid climate regime with reduced seasonality despite the high insolation precession minima values forcing we find that the dominant forcing on the long term temperate forest development was obliquity which may have induced a decrease in summer dryness and associated reduction in seasonal precipitation contrast moreover this study provides the first evidence for persistent atmospheric millennial scale variability during this interval with multiple forest decline events reflecting repeated cooling and drying episodes in sw iberia our direct land sea comparison shows that the expression of the suborbital cooling events on sw iberian ecosystems is modulated by the predominance of high or low latitude forcing depending on the glacial interglacial baseline climate states severe dryness and air sea cooling is detected under the larger ice volume during glacial mis 32 and mis 30 the extreme episodes which in their climatic imprint are similar to the heinrich events are likely related to northern latitude ice sheet instability and a disruption of the atlantic meridional overturning circulation amoc in contrast forest declines during mis 31 are associated to neither sst cooling nor high latitude freshwater forcing time series analysis reveals a dominant cyclicity of about 6 ky in the temperate forest record which points to a potential link with the fourth harmonic of precession and thus low latitude insolation forcing

on the structure and origin of major glaciation cycles 2 the 100 000 year cycle climate over the past million years has been dominated by glaciation cycles with periods near 23 000 41 000 and 100 000 years in a linear version of the milankovitch theory the two shorter cycles can be explained as responses to insolation cycles driven by precession and obliquity but the 100 000 year radiation cycle arising from eccentricity variation is much too small in amplitude and too late in phase to produce the corresponding climate cycle by direct forcing we present phase observations showing that the geographic progression of local responses over the 100 000 year cycle is similar to the progression in the other two cycles implying that a similar set of internal climatic mechanisms operates in all three but the phase sequence in the 100 000 year cycle requires a source of climatic inertia having a time constant similar to 15 000 years much larger than the other cycles similar to 5 000 years our conceptual model identifies massive northern hemisphere ice sheets as this larger inertial source when these ice sheets forced by precession and obliquity exceed a critical size they cease responding as linear milankovitch slaves and drive atmospheric and oceanic responses that mimic the externally forced responses in our model the coupled system acts as a nonlinear amplifier that is particularly sensitive to eccentricity driven modulations in the 23 000 year sea level cycle during an interval when sea level is forced upward from a major low stand by a milankovitch response acting either alone or in combination with an internally driven higher frequency process ice sheets grounded on continental shelves become unstable mass wasting accelerates and the resulting deglaciation sets the phase of one wave in the train of 100 000 year oscillations whether a glacier or ice sheet influences the climate depends very much on the scale the interesting aspect is that an effect on the local climate can still make an ice mass grow larger and larger thereby gradually increasing its radius of influence

vegetation response to upper pliocene glacial interglacial cyclicity in the central mediterranean abstract new detailed pollen analysis of the lower part of the upper pliocene semaforo section crotone italy documents cyclic behavior of vegetation at the beginning of the northern hemisphere glaciations the competition between four vegetation units subtropical humid forest deciduous temperate forest altitudinal coniferous forest and open xeric assemblage probably reflects modifications of vegetation belts at this montane site several increases in herbaceous open vegetation regularly alternate with subtropical humid forest which expresses rapid climatic oscillations the complete temporal succession deciduous forest rich in quercus followed by subtropical humid forest taxodiaceae and cathaya then altitudinal coniferous forest tsuga cedrus abies and picea and finally herbaceous open vegetation graminae compositae and artemisia displays the climatic evolution from warm and humid interglaciation to cold and dry glaciation it also suggests an independent variation of temperature and humidity the two main climatic parameters the vegetation history of southern calabria recorded in the semaforo section have been correlated with the 18o signal established in the atlantic ocean

vegetation and palaeoclimatic reconstruction of the sousaki basin eastern gulf of corinth greece during the early pleistocene abstract pollen analysis was performed on a lower pleistocene lacustrine sedimentary sequence outcropping in sousaki basin eastern gulf of corinth greece for the first time the palynological assemblages revealed a stable climate with regard to the glacial interglacial climate variability timescale with minor fluctuations in humidity expressed as a relatively wet phase between 13 1 and 19 3 m and some transient increased aridity and humidity events a mediterranean type of vegetation presenting altitudinal zonation was evidenced for the first time in this region pinus and quercus dominate accompanied by other arboreal and non arboreal plants the presence of rare taxa such as taxodiaceae engelhardia liquidambar tsuga and cedrus in very low percentages shows that these taxa remained in the area as relicts sometime between 2 8 and 1 5ma palaeovegetation patterns from the balkan peninsula are lacking especially during the early pleistocene thus in this study a palaeoclimate reconstruction of the early pleistocene sousaki basin based on palynological data is presented accentuating the effect of global climate changes in an area where no other similar records exist