sediment fluxes along the northeastern european margin inferring hydrological changes between 20 and 8 kyr abstract in an attempt to delineate past hydrographic conditions on the northeastern atlantic ocean margin along a latitudinal transect 37 63 n and link the eastern north atlantic ocean with the norwegian sea we have investigated planktonic and benthic stable oxygen isotopes as well as abundances and fluxes of planktonic and benthic foraminifera calcium carbonate organic carbon and detrital grains in six sediment cores studied by the enam project in our joint approach we focused on the major climatic events of the last 20 kyr that is the last glacial maximum lgm the heinrich event 1 h1 the younger dryas yd and the holocene climatic optimum hco simmax temperature estimates suggest glacial ssts off portugal similar to holocene values contradicting the proposed polar front position of climap project members 1976 besides increased planktonic and benthic foraminiferal fluxes in the norwegian sea and the faeroe islands cores point to nordic seas partially ice free with seasonally productive polynas multiple ird spikes observed at the faeroe islands and norwegian sea sites coeval with h1 suggest multiple pulses of the fenno scandian ice sheet at the same time the presence of ird on the portuguese margin cores confirms the southward influence of icebergs the increase in foraminiferal abundances and fluxes that parallel ird spikes at all sites suggests that times of increased productivity either succeed or occur simultaneously with the iceberg surges in the open north atlantic productivity conditions similar to those observed during h1 are also registered during the yd even though planktonic foraminiferal assemblages suggest less cold conditions

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

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

the 2002 denali fault earthquake alaska a large magnitude slip partitioned event the mw moment magnitude 7 9 denali fault earthquake on 3 november 2002 was associated with 340 kilometers of surface rupture and was the largest strike slip earthquake in north america in almost 150 years it illuminates earthquake mechanics and hazards of large strike slip faults it began with thrusting on the previously unrecognized susitna glacier fault continued with right slip on the denali fault then took a right step and continued with right slip on the totschunda fault there is good correlation between geologically observed and geophysically inferred moment release the earthquake produced unusually strong distal effects in the rupture propagation direction including triggered seismicity

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

the latest lgm culmination of the garda glacier italian alps and the onset of glacial termination age of glacial collapse and vegetation chronosequence abstract in the deglacial sequence of the largest end moraine system of the italian alps we focused on the latest culmination of the last glacial maximum before a sudden downwasting of the piedmontane lobe occupying the modern lake basin we obtained a robust chronology for this culmination and for the subsequent deglacial history by cross radiocarbon dating of a proximal fluvioglacial plain and of a deglacial continuous lake sedimentation we used reworked dinocysts to locate sources of glacial abrasion and to mark the input of glacial meltwater until depletion the palynological record from postglacial lake sediments provided the first vegetation chronosequence directly reacting to the early lateglacial withdrawal so far documented in the alps glacier collapse occurred soon after 17 46 0 2 ka cal bp which is the manerba advance culmination basin deglaciation of several overdeepened foreland piedmont lakes on southern and northern sides of the alps appears to be synchronous at millennial scale and near synchronous with large scale glacial retreat at global scale the pioneering succession shows a first afforestation step at a median modeled age of 64 years after deglaciation while rapid tree growth lagged 7 centuries between 16 4 0 16 and 15 5 0 16 ka cal bp a regressive phase interrupted forest growth marking a lateglacial phase of continental dry climate predating gi 1 this event spanning the most advanced phases of north atlantic h1 is consistently radiocarbon framed at three deglacial lake records so far investigated on the italian side of the alps relationships with the gschnitz stadial from the alpine record of lateglacial advances are discussed

comment on paleoclimatic record of the past 22 000 years in venice northern italy biostratigraphic evidence and chronology by serandrei barbero et al quaternary international 140 141 37 52 interstadials or phases of accumulation of reworked pollen

weichselian palynostratigraphy palaeovegetation and palaeoenvironment the record from lago grande di monticchio southern italy abstract the palynostratigraphic record from lago grande di monticchio s italy is presented an independent sedimentation rate based chronology provides an age of 101 530 calendar years bp for the lowermost sediments sampled this chronology enables assessment of the rapidity of vegetation changes during the last glacial contrary to widely held views the vegetation showed numerous large magnitude changes in periods of

chironomid inferred air temperatures from lateglacial and holocene sites in north west europe progress and problems abstract non biting midges insecta diptera chironomidae are now widely recognised as powerful biological proxies for inferring past climatic change in this paper the response of chironomid assemblages to lateglacial and holocene climatic change from sites in scotland and norway is discussed analyses have shown that midge assemblages have responded to major and minor climatic fluctuations during the last 15 000 yr such as the aegelsee oscillation gerzensee oscillation and younger dryas in the lateglacial and the thermal optimum little ice age and cooling events at 8 2 and 2 0 cal ka bp in the holocene in an attempt to quantify these and other climatic fluctuations a chironomid mean july air temperature inference model based on a modern calibration set of 109 lakes in norway and svalbard has been developed the 3 component weighted averaging partial least squares inference model performs well with a root mean squared error of prediction of 0 90 c and a maximum bias of 0 59 c both based on leave one out cross validation which is lower than chironomid temperature inference models developed in canada switzerland and finland however while temperature inference models perform well in the lateglacial the more subtle climatic changes of the holocene are more difficult to reconstruct because the likely temperature changes are close to the limits of the prediction errors of the existing models to address this problem future work is required to refine and develop the calibration set by further improving taxonomic resolution by adding more lakes to the calibration set and by investigating the influence of other environmental variables on chironomid distributions and abundances

environmental and climatic conditions at a potential glacial refugial site of tree species near the southern alpine glaciers new insights from multiproxy sedimentary studies at lago della costa euganean hills northeastern italy abstract it has been hypothesized that refugia of thermophilous tree species were located in northern italy very close to the alps though this hypothesis has yet to be tested thoroughly in contrast to central and southern italy with its relative wealth of data only a few fragmentary records are currently available from northern italy for the last glacial wurm weichselian our new study site lago della costa lies adjacent to the catchment of the megafans of the alpine forelands and the braided rivers of the northeastern po plain that have so far inhibited the recovery of continuous glacial and late glacial records we analyze pollen plant macrofossils charcoal and ostracods to reconstruct the vegetation fire and lake history for the period 33 000 16 000 cal bp we compare our data with glacial records from southern europe to discuss similarities and dissimilarities between these potential refugial areas a comparison with independent paleoclimatic proxies allows to assess potential linkages between environmental and climatic variability new macrofossil and pollen data at lago della costa unambiguously document the local persistence of boreal tree taxa such as larix decidua and betula tree species around the study site during the last glacial the regular occurrence of pollen of temperate trees in the organic lake sediments fine detritus calcareous gyttja suggests that temperate taxa such as corylus avellana quercus deciduous tilia ulmus fraxinus excelsior carpinus abies alba and fagus sylvatica most likely survived the last glacial maximum lgm at favorable sites in the euganean hills the percentage values of temperate trees are comparable with those from southern europe e g monticchio in southern italy we conclude that the euganean hills were one of the northernmost refugial areas of temperate taxa in europe however the relative and absolute abundances of pollen of temperate trees are highly variable pollen inferred declines of temperate tree communities e g quercetum mixtum and low ostracod inferred water levels at lago della costa correspond to the cold heinrich events h 2 lgm 23 000 19 000 cal bp and h 3 around 28 000 cal bp as recorded in the marine sediments of the north atlantic similar patterns of significant temperate tree population collapses during cold heinrich events are recorded at southern mediterranean sites e g monticchio and the alboran sea these findings suggest close linkages between northern atlantic and south central european climates during the past glacial

vegetation history and palaeoclimate of the last glacial period at lago grande di monticchio southern italy a high resolution palynological study of a 51 m core from lago grande di monticchio southern italy has provided a palaeonvironmental record for the last glacill a annual lamination based chronology supported by radiometric and tephrochronological dates provides an absolute timescale for this record that spans 76 300 years correlations are established between the pollen stratigraphy the grip ice core 18o record and foraminiferal assemblages from atlantic core v23 81 both dansgaard oeschger and heinrich events are reflected by changes in the pollen stratigraphy revised dates are estimated for heinrich events h1 h6 a quantitative palaeoclimate reconstruction based upon the pollen data provides evidence of the climate changes in southern italy associated with these and other fluctuations during the last glacial

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

reconstruction of full glacial environments and summer temperatures from lago della costa a refugial site in northern italy abstract vegetation and climate during the last ice age and the last glacial maximum lgm 23 000 19 000 cal bp were considerably different than during the current interglacial holocene cold climatic conditions and growing ice sheets during the last glaciation radically reduced forest extent in europe to a restricted number of so called refugia mostly located in the southern part of the continent on the basis of paleobotanical analyses the euganian hills colli euganei in northeastern italy have previously been proposed as one of the northernmost refugia of temperate trees e g deciduous quercus tilia ulmus fraxinus excelsior acer abies alba fagus sylvatica carpinus and castanea in europe in this study we provide the first quantitative vegetation independent summer air temperature reconstruction for northern italy spanning the time 31 000 17 000 cal yr bp which covers the coldest periods of the last glacial including the lgm and heinrich stadials 1 to 3 chironomids preserved in a lake sediment core from lago della costa 7m a s l a small lake at the south eastern edge of the euganean hills allowed quantitative reconstruction of full and late glacial summer air temperatures using a combined swiss norwegian temperature inference model based on chironomid assemblages from 274 lakes chironomid and pollen evidence from lago della costa derives from finely stratified autochthonous organic gyttja sediments which excludes major sediment mixing or reworking after reconstructing paleo temperatures we address the question whether climate conditions were warm enough to permit the local survival of temperate tree species during the lgm and whether local expansions and pollen inferred contractions of temperate tree taxa coincided with chironomid inferred climatic changes our results suggest that chironomids at lago della costa have responded to major climatic fluctuations such as temperature decreases during the lgm and heinrich stadials the vegetation of the euganean hills shows responses to these climatic oscillations although the effects of temperature changes were probably also strongly influenced by changes in humidity reconstructed july air temperatures at lago della costa never fell below 10 13 c error range of reconstruction 1 5 1 6 c which is considerably above the limit considered necessary for forest growth 8 10 c instead rather mild climatic conditions prevailed 31 000 17 000 cal yr bp with average summer temperatures between 12 and 16 c which most likely allowed survival of temperate tree taxa in the warmest and moistest microhabitats of the euganean hills during the lgm only assuming local survival is it possible to explain the repeated expansions and collapses of temperate trees at lago della costa which faithfully accompanied the climatic oscillations

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

ecological thresholds and patterns of millennial scale climate variability the response of vegetation in greece during the last glacial period the regional expression of millennial scale climate variability during the last glacial is examined with particular reference to the vegetation response in greece inspection of three pollen records from contrasting bioclimatic areas suggests that differences in the magnitude of cold events as recognized in the north atlantic and western mediterranean are expressed in terms of tree population changes only in areas with a range of favorable habitats by contrast records from sites where populations approach their tolerance threshold do not appear to resolve differences in the amplitude of the climate oscillations understanding the importance of local factors in modulating the biological response to climate change is critical when attempting to establish the spatial pattern of millennial variability

last glacial maximum temperatures over the north atlantic europe and western siberia a comparison between pmip models margo sea surface temperatures and pollen based reconstructions abstract evaluating the ability of models to simulate climates different from the modern one is important for climate prediction here we present a first comparison between results from simulations of the last glacial maximum climate and continental and surface ocean reconstructions for the north atlantic europe and western siberia the simulations include prescribed sea surface temperature sst and slab ocean atmospheric general circulation model runs performed within the pmip1 project and atmosphere ocean fully coupled runs performed after pmip1 and within the pmip2 project the surface ocean reconstructions are from the margo project continental reconstructions are based on pollen data over the north atlantic most models simulate the strengthening of the sst meridional gradient suggested by the reconstructions but most do not reproduce the lgm control sst anomaly at the right location nor with the right amplitude over western siberia the model results are much improved when a new ice sheet reconstruction ice 5g is used to force the models the main discrepancy remains for western europe winter temperatures for which lgm control anomalies are significantly underestimated by all models all models indicate that this region during the lgm experienced significantly higher interannual variability in coldest month temperatures compared to the control runs this increased variability could have conspired to bias the apparently extremely cold pollen based temperature reconstructions

a combined pollen and δ18osphagnum record of mid holocene climate variability from durres maar eifel germany in this study we investigate pollen and oxygen isotopes of moss cellulose from the peat bog durres maar in the eifel low mountain range germany 450 m a s l to quantitatively infer mid holocene climate change for the period between 7000 and 3800 cal bp pollen was analysed on the same samples from which sphagnum leaves were isolated to extract cellulose for the determination of its oxygen isotope composition 18osphagnum to quantitatively estimate january and july temperature and annual precipitation from the pollen data we applied a probabilistic indicator taxa method pdf method the pollen based reconstructions indicate july temperatures 1 c higher around 6000 cal bp than after 5500 cal bp which is consistent with a 1 decrease in 18osphagnum during the same period while the pollen based climate reconstructions indicate little variability in summer temperature after 5500 cal bp winter temperature shows several pronounced cold excursions of 2 4 c in this period which was likel

major cooling intersecting peak eemian interglacial warmth in northern europe abstract the degree of climate instability on the continent during the warmer than present eemian interglacial around ca 123 kyr ago remains unsolved recently published high resolution proxy data from the north atlantic ocean suggest that the eemian was punctuated by abrupt events with reductions in north atlantic deep water formation accompanied by sea surface temperature cooling here we present multi proxy data at an unprecedented resolution that reveals a major cooling event intersecting peak eemian warmth on the north european continent two independent temperature reconstructions based on terrestrial plants and chironomids indicate a summer cooling of the order of 2 4 c the cooling event started abruptly had a step wise recovery and lasted 500 1000 yr our results demonstrate that the common view of relatively stable interglacial climate conditions on the continent should be revised and that perturbations in the north atlantic oceanic circulation under warmer than present interglacial conditions may also lead to abrupt and dramatic changes on the adjacent continent

the full glacial forests of central and southeastern europe the presence of trees in central and southern europe during the last full glaciation has long been a matter of debate a low but persistent presence of fossil tree pollen in central and southern european full glacial paleoecological sequences has been interpreted either as representing long distance pollen transport from southerly refuges or as representing in situ refugial populations here we present macroscopic charcoal results from 31 sequences located throughout hungary that provide unequivocal evidence for the presence of at least seven different tree types between approximately 32 500 and 16 500 14c yr b p this evidence is presented in conjunction with molluscan and pollen analyses to indicate that during the last full glaciation trees grew as far north as hungary probably in microenvironmentally favorable sites these areas provided an important cold stage refugium for the european flora and fauna

a new concept for the paleoceanographic evolution of heinrich event 1 in the north atlantic new records of planktonic foraminiferal 18o and lithic and foraminiferal counts from eirik drift are combined with published data from the nordic seas and the ice rafted debris ird belt to portray a sequence of events through heinrich event 1 h1 these events progressed from an onset of meltwater release at not vert similar19 ka bp through the conventional h1 ird deposition phase in the ird belt starting from not vert similar17 5 ka bp to a final phase between 16 5 and not vert similar15 ka bp that was characterised by a pooling of freshwater in the nordic seas which we suggest was hyperpycnally injected into that basin after not vert similar15 ka bp this freshwater was purged from the nordic seas into the north atlantic which preconditioned the nordic seas for convective deep water formation this allowed an abrupt re start of north atlantic deep water nadw formation in the nordic seas at the bolling warming 14 6 ka bp in contrast to previous estimates for the duration of h1 i e 1000 years to only a century or two the total combined composite h1 signal presented here had a duration of over 4000 yrs not vert similar19 14 6 ka bp which spanned the entire period of nadw collapse it appears that deep water formation and climate are not simply controlled by the magnitude or rate of meltwater addition instead the location of meltwater injections may be more important with nadw formation being particularly sensitive to surface freshening in the arctic nordic seas

eemian and early weichselian temperature and precipitation variability in northern germany abstract dramatic changes in european vegetation occurred during the transition from the eemian interglacial to weichselian glacial climates correlative with major changes in global ice core and marine records quantitative knowledge of climate change is important for understanding of the climate system and for climate modelling for which reconstructions of this transitional period are of special interest however it has been difficult to quantify the climatic changes involved in the eemian to early weichselian transition from terrestrial archives due to the lack of modern vegetation analogues to circumvent this problem we applied a suitable multivariate probabilistic approach to pollen and plant macrofossil assemblages to reconstruct temperature and precipitation for this transition in central europe our reconstructions span the interval from the beginning of the eemian marine isotope stage mis 5e to the odderade interstadial mis 5a they indicate a relatively stable eemian with increasing precipitation reducing the continentality of the climate with time during the transition from the eemian to the herning stadial mean july and january temperatures decreased by 4 c and by as much as 20 c respectively temperatures remained high enough to support forests during the stadials and we infer that the reconstructed decrease of precipitation below 500 mm per year caused the extirpation of forests during these periods thus we conclude that precipitation although difficult to reconstruct is of vital importance for explaining vegetation change during the eemian and eemian early weichselian transition

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

diamictite and oolitic ironstones a sedimentary association at ordovician silurian transition in the north gondwana margin new evidence from the inner nappe of sardinia variscides italy abstract the contact between the silurian black phyllite and the cambro ordovician underlying rocks has been investigated over different tectonic units affected by green schist facies metamorphism in the inner nappe zone of the sardinia variscides in spite of strain and metamorphism the field work highlighted the occurrence of diamictic sediments in the canaglia tectonic unit the diamictite consists of dark massive metamorphic claystone bearing chamositic ooliths chamositic nodules and millimetre to centimetre sized clasts dispersed or gathered in clusters within the muddy matrix in the argentiera tectonic unit the diamictite consists of angular clasts ranging in size from few millimetres to several decimetres scattered within a finely laminated black sericitic meta argillite field data textural and compositional analyses suggest a glacio marine environment for the formation of the diamictites the canaglia diamictite deposited in a protected glacial influenced shore compositionally it can be defined as ironstone in the upper part it hosts a horizon of clast supported conglomeratic hard ironstone mostly made of magnetite which testifies for sub aerial reworking the source of the iron is to be related to local glacio eustatic driven emergence of upper ordovician alkaline mafic volcanics these are widespread in the uppermost ordovician of the canaglia unit possibly linked to the rifting stage that invested the north gondwana margin before the uppermost ordovician early silurian sea level rise the argentiera diamictite deposited beyond the iron rich diamictite in the outer euxinic shelf that was reached by rain out of rafted debris

temperature and productivity changes off the western iberian margin during the last 150 ky abstract present day hydrographic conditions along the western iberian margin are characterized by seasonal upwelling with filaments that can penetrate more than 200 km into the open ocean and constitute areas of cold and highly productive waters in order to investigate spatial and temporal gradients in temperature and productivity conditions during the last 150 ky high resolution proxy records were generated in 3 cores su92 03 md95 2040 md95 2042 located along the iberian coast between 43 12 n and 37 48 n and forming a n s profile in all cores planktonic foraminifera census counts are used to reconstruct summer sea surface temperature sstsu and export productivity pexpsu using the modern analog technique simmax 28 sstsu and pexpsu values similar to the present are observed throughout the holocene and mis 5e periods for each site respectively indicating fairly stable conditions equivalent to the modern ones on glacial interglacial timescales sstsu increases by 2 3 c from the northern to southernmost site pexpsu on the other hand shows a decrease of 30 40 gc m2 yr from north to south at present time and during interglacial periods and no significant variation 90 100 gc m2 yr during glacial periods the northernmost core su92 03 reveals the coldest conditions with records more similar to md95 2040 than to md95 2042 the later of which is as at present more affected by subtropical waters core su92 03 shows higher interglacial productivity similar to open ocean mid to high latitude sites while the other two cores monitor higher glacial productivity conform with other upwelling sites off nw africa a boundary between differences in glacial interglacial productivity appears to be present in our study between 43 12 n and 40 35 n especially north of 40 n coldest sstsu and lowest pexpsu are found during heinrich events h 1 h8 and h10 h11 in contrast lowest pexpsu do not coincide with these events at site md95 2042 but appear to be related to the presence of relatively warm and nutrient poor subtropical eastern north atlantic central water advected with the azores current

responses of terrestrial ecosystems to dansgaard oeshger cycles and heinrich events a 28 000 year record of environmental changes from se hungary abstract according to the findings of a complex sedimentological geochemical malacological and pollen study implemented on a core sequence of an alkaline lake feher lake interstadials in the se great hungarian plain were characterized by increased boreal woodland cover during marine isotope stage 2 mis 2 29 700 14 500 cal bp these interstadials were dated to 26 420 27 970 23 185 24 880 and 18 810 20 770 cal bp and correlate well with the dansgaard oeschger do interstadials 2 and 3 and the post lgm warm interval seen in the greenland ice core oxygen isotope records intervening cold phases on the other hand were found between 24 880 26 420 and 20 770 23 185 cal bp correlating with heinrich event 2 and the lgm these data overall confirm that millennial scale climate variability during marine isotope stage 2 had profound effect on the terrestrial ecosystems in the continental interior of se europe leading to periodic boreal woodland expansions and contractions and wildfires

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

variability of the western mediterranean sea surface temperature during the last 25 000 years and its connection with the northern hemisphere climatic changes sea surface temperature sst profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a w e latitudinal transect encompassing the gulf of cadiz atlantic ocean the alboran sea and the southern tyrrhenian sea western mediterranean the results document the sensitivity of the mediterranean region to the short climatic changes of the north atlantic ocean particularly those involving the latitudinal position of the polar front the amplitude of the sst oscillations increases toward the tyrrhenian sea indicating an amplification effect of the atlantic signal by the climatic regime of the mediterranean region all studied cores show a shorter cooling phase 700 years for the younger dryas yd than that observed in the north atlantic region 1200 years this time diachroneity is related to an intra yd climatic change documented in the european continent minor oscillations in the southward displacement of the north atlantic polar front may also have driven this early warming in the studied area during the holocene a regional diachroneity propagating west to east is observed for the sst maxima 11 5 10 2 kyr b p in the gulf of cadiz 10 9 kyr b p in the alboran sea and 8 9 8 4 kyr b p in the thyrrenian sea a general cooling trend from these sst maxima to present day is observed during this stage which is marked by short cooling oscillations with a periodicity of 730 40 years and its harmonics

a quantitative midge based reconstruction of mean july air temperature from a high elevation site in central colorado usa for mis 6 and 5 abstract sediments recovered from the ziegler reservoir fossil site zrfs in snowmass village colorado usa were analyzed for subfossil chironomids or midges the midge stratigraphy spans 140 77 ka which includes the end of marine oxygen isotope stage mis 6 and all of mis 5 notable shifts in midge assemblages occurred during two discrete intervals the transition from mis 6 to mis 5e and midway through mis 5a a regional calibration set incorporating lakes from the colorado rockies sierra nevada and uinta mountains was used to develop a midge based mean july air temperature mjat inference model r2jack 0 61 rmsep 0 97 c model results indicate that the transition from mis 6 to mis 5e at the zrfs was characterized by an increase in mjat from 9 0 to 10 5 c the results also indicate that temperatures gradually increased through mis 5 before reaching a maximum of 13 3 c during mis 5a this study represents the first set of quantitative midge based mjat estimates in the continental u s that spans the entirety of mis 5 overall our results suggest that conditions in the colorado rockies throughout mis 5 were cooler than today as the upper limit of the reconstructed temperatures is 2 c below modern july air temperatures

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

chironomid inferred temperature changes of the last century in anoxic seebergsee switzerland assessment of two calibration methods abstract chironomids non biting midges can provide accurate climate reconstructions from the late glacial to the present until now anoxic lakes have been avoided for temperature reconstructions since chironomid assemblages are sensitive to changes in oxygen concentrations in the hypolimnion however anoxic lakes may have varved sediments providing the possibility for near annual climate reconstructions here we tested the applicability of two calibration methods to reconstruct mean july air temperatures from chironomid assemblages preserved in the sediments of the anoxic seebergsee located in the northern swiss alps a calibration in space approach and a calibration in time approach the calibration in space approach i e chironomid assemblages from surficial lake sediments 0 1 cm calibrated against meteorological data provided accurate inferences i e similar temperature changes as measured at the closest meteorological station and at regional stations in the seebergsee stratigraphy until anoxia increased in the lake with the increase of anoxia the chironomid inferred temperatures were generally colder than measured temperatures a calibration in time approach i e calibration of chironomid assemblages in a time series against instrumental data from the closest meteorological station provided accurate reconstructions i e similar to the regional records for the past 100 years including the time period of inferred anoxia however its applicability should be further tested on longer temporal scales

heinrich events massive late pleistocene detritus layers of the north atlantic and their global climate imprint 1 millennial climate oscillations of the glacial interval are interrupted by extreme events the so called heinrich events of the north atlantic their near global footprint is a testament to coherent interactions among earth s atmosphere oceans and cryosphere on millennial timescales heinrich detritus appears to have been derived from the region around hudson strait it was deposited over approximately 500 250 years several mechanisms have been proposed for the origin of the layers binge purge cycle of the laurentide ice sheet jokulhlaup activity from a hudson bay lake and an ice shelf buildup collapse fed by hudson strait to determine the origin of the heinrich events i recommend 1 further studies of the timing and duration of the events 2 further sedimentology study near the hudson strait and 3 greater spatial and temporal resolution studies of the layers as well as their precursory intervals studies of previous glacial intervals may also provide important constraints

north atlantic control on precipitation pattern in the eastern mediterranean black sea region during the last glacial based on proxy records from western black sea cores we provide a comprehensive study of climate change during the last glacial maximum and late glacial period in the black sea region for the first time we present a record of relative changes in precipitation for nw anatolia based on variations in the terrigenous supply expressed as detrital carbonate concentration the good correspondence between reconstructed rainfall intensity in nw anatolia and past western mediterranean sea surface temperatures ssts implies that during the glacial period the precipitation variability was controlled like today by mediterranean cyclonic disturbances periods of reduced precipitation correlate well with low ssts in the mediterranean related to heinrich events h1 and h2 stable oxygen isotopes and lithological and mineralogical data point to a significant modification in the dominant freshwater sediment source concomitant to the meltwater inflow after 16 4 cal ka bp this change implies intensification of the northern sediment source and with other records from the mediterranean region consistently suggests a reorganization of the atmospheric circulation pattern affecting the hydrology of the european continent the early deglacial northward retreat of both atmospheric and oceanic polar fronts was responsible for the warming in the mediterranean region leading simultaneously to more humid conditions in central and northern europe