human environment interaction during the holocene along the shoreline of the ancient lake ladoga a case study based on palaeoecological and archaeological material from the karelian isthmus russia this paper presents the results of pollen diatom charcoal and sediment analyses from lake bol shoye zavetnoye situated between the gulf of finland and lake ladoga on the karelian isthmus north

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

late glacial climatic changes in eastern france lake lautrey from pollen lake levels and chironomids high temporal resolution analyses of pollen chironomid and lake level records from lake lautrey provide multi proxy quantitative estimates of climatic change during the late glacial period in eastern france past temperature and moisture parameters were estimated using modern analogues and plant functional types transfer function methods for three pollen records obtained from different localities within the paleolake basin the comparison of these methods shows that they provide generally similar climate signals with the exception of the bolling comparison of pollen and chironomid based temperature of the warmest month reconstructions generally agree except during the bolling major abrupt changes associated with the oldest dryas bolling allerod younger dryas and the younger dryas preboreal transitions were quantified as well as other minor fluctuations related to the cold events e g preboreal oscillation the temperature of the warmest month increased by not vert similar5 c at the start of bolling and by 1 5 3 c at the onset of the holocene while it fell by ca 3 to 4 c at the beginning of younger dryas the comparative analysis of the results based on the three lautrey cores have highlighted significant differences in the climate reconstructions related to the location of each core underlining the caution that is needed when studying single cores not taken from deepest part of lake basins

assessing the importance of climate variables for the spatial distribution of modern pollen data in china to assess the importance of climate variables for the distribution of modern pollen data in china we present a continental scale dataset consisting of 1374 samples boosted regression trees and constrained ordination techniques are employed to quantify the importance of six climate variables annual precipitation pann actual potential evapotranspiration ratio alpha mean annual temperature tann mean temperature of the warmest month mtwa mean temperature of the coldest month mtco annual sum of the growing degree days above 5 c gdd5 for the distribution of individual pollen taxa and modern pollen assemblages the results show that taxon specific responses to the climate variables display a wide regional diversity and that the climate variables with low collinearity that best account for the spatial variability of modern pollen assemblages differ regionally pann is the most important variable in northwestern and northeastern china and the tibetan plateau while mtwa and mtco are the dominant variables in east central and southern china this suggests that the climate variables that can be optimally reconstructed from fossil pollen data vary in different bioclimatic regions of china this feature is typical to many continental scale modern pollen datasets and needs to be considered in pollen based climate reconstructions

holocene dynamics of the southern boreal forest in sweden holocene vegetation dynamics in the ecotone between the boreo nemoral and boreal forest were reconstructed from sediment cores of two small lakes using pollen and macrofossil analyses competition

pollen based continental climate reconstructions at 6 and 21 ka a global synthesis subfossil pollen and plant macrofossil data derived from 14c dated sediment profiles can provide quantitative information on glacial and interglacial climates the data allow climate variables related to growing season warmth winter cold and plant available moisture to be reconstructed continental scale reconstructions have been made for the mid holocene mh around 6 ka and last glacial maximum lgm around 21 ka allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth assessment report ar5 of the intergovernmental panel on climate change the synthesis of the available mh and lgm climate reconstructions and their uncertainties obtained using modern analogue regression and model inversion techniques is presented for four temperature variables and two moisture variables reconstructions of the same variables based on surface pollen assemblages are shown to be accurate and unbiased reconstructed lgm and mh climate anomaly patterns are coherent consistent between variables and robust with respect to the choice of technique they support a conceptual model of the controls of late quaternary climate change whereby the first order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance

a method for climate and vegetation reconstruction through the inversion of a dynamic vegetation model climate reconstructions from data sensitive to past climates provide estimates of what these climates were like comparing these reconstructions with simulations from climate models allows to validate the models used for future climate prediction it has been shown that for fossil pollen data gaining estimates by inverting a vegetation model allows inclusion of past changes in carbon dioxide values as a new generation of dynamic vegetation model is available we have developed an inversion method for one model lpj guess when this novel method is used with high resolution sediment it allows us to bypass the classic assumptions of 1 climate and pollen independence between samples and 2 equilibrium between the vegetation represented as pollen and climate our dynamic inversion method is based on a statistical model to describe the links among climate simulated vegetation and pollen samples the inversion is realised thanks to a particle filter algorithm we perform a validation on 30 modern european sites and then apply the method to the sediment core of meerfelder maar germany which covers the holocene at a temporal resolution of approximately one sample per 30 years we demonstrate that reconstructed temperatures are constrained the reconstructed precipitation is less well constrained due to the dimension considered one precipitation by season and the low sensitivity of lpj guess to precipitation changes

climatic reconstruction in europe for 18 000 yr b p from pollen data an improved concept of the best analogs method is used to reconstruct the climate of the last glacial maximum from pollen data in europe in order to deal with the lack of perfect analogs of fossil assemblages and therefore to obtain a more accurate climate reconstruction we used a combination of pollen types grouped according to plant phenology and present climate constraints rather than pollen percentages for each individual taxon the distribution of pollen taxa into plant functional types pfts is aimed to reflect the vegetation in terms of biomes which have a wider distribution than a species the climatic variables are then calibrated on these pfts using an artificial neural network technique the use of pfts allowed us to deal with situations where pollen assemblages have only partial modern analogs the method is applied to the glacial steppic vegetation in europe using 15 pollen records north of the pyrenees alps line the reconstructed temperatures were lower than today 30 10 degrees c for the temperature of the coldest month t c and 12 3 degrees c far the annual mean t ann south of that line t c and t ann anomalies were respectively 15 5 degrees c and 10 5 degrees c the available moisture index and annual precipitation were also lower than present 60 20 north of mediterranean sea 800 100 mm for precipitation in italy and greece the available moisture was 20 lower with a precipitation anomaly of ca 600 200 mm southward the moisture index was close to that at present 20 and precipitation was lower 300 300 mm c 1998 university of washington

the climate in europe during the eemian a multi method approach using pollen data the last interglacial period the eemian offers a testbed for comparing climate evolution throughout an interglacial with the current warm period we present here results from climatic reconstructions from 17 sites distributed across the european continent allowing an assessment of trends and regional averages of climate changes during this period we use a multi method approach to allow for an improved assessment of the uncertainties involved in the reconstruction in addition the method takes into account the errors associated with the age model the resulting uncertainties are large but allow a more robust assessment of the reconstructed climatic variations than in previous studies the results show a traditional three part eemian with an early optimum followed by slight cooling and eventually a sharp drop in both temperatures and precipitation this sequence is however restricted to the north as this latter change is not observed in the south where temperatures remain stable for longer these variations led to marked variation in the latitudinal temperature gradient during the eemian the difference between the two regions is also noticeable in the magnitude of changes with greater variations in the north than the south some evidence is found for changes in lapse rates however a greater number of sites is needed to confirm this

exploring holocene continentality changes in fennoscandia using present and past tree distributions with global warming the distribution of warmth through the year is likely to change in the future and comparable changes may have occurred over the course of the holocene its effect on vegetation composition and species distribution can be compared to that of a continental versus an oceanic climate the distribution of five major tree species along a continentality gradient was studied in fennoscandia based on distribution maps and on their proportions of pollen in surface sediment samples both analyses indicate that the five arboreal species show similar patterns of response to a continentality index in the order ulmus glabra corylus avellana quercus robur tilia cordata and picea abies from the most oceanic to most continental continentality growing degree days above 5 degrees c and january temperature were reconstructed quantitatively from four pollen diagrams using transfer functions based on a combined fennoscandian pollen surface sample data set quantitative reconstructions indicate that the climate in fennoscandia has become increasingly more continental over the last 7000 years and this is largely an effect of winter cooling early holocene vegetation composition has poor analogues to the present vegetation in fennoscandia which hampers quantitative reconstructions qualitative reconstructions suggest that the early holocene in fennoscandia was the most oceanic period but probably with a high variability in temperature c 2008 elsevier ltd all rights reserved

expanded response surfaces a new method to reconstruct paleoclimates from fossil pollen assemblages that lack modern analogues pollen based paleoclimatic interpretations of late glacial to early holocene climates 17 9 ka in midwestern north america are hampered by samples that lack modern analogues unresolved questions include the magnitude and direction of temperature seasonality i e were these climates more or less seasonal than present and the temporal changes in precipitation central to the no analogue problem is the truncation of modern pollen climate relationships for abundant late glacial taxa such as fraxinus here we present a new method called the expanded response surface ers method developed to reconstruct climates from no analogue pollen assemblages and applied to a high resolution late glacial pollen record from crystal lake illinois to test hypotheses about late glacial climates the key assumptions central to the ers method are 1 plant species and pollen abundances follow symmetrical unimodal distributions along climatic gradients 2 taxa with truncated distributions in modern climate space occupy a subset of their fundamental niche and 3 expansion of truncated distributions by mirroring around the distributional mode recovers the portion of the fundamental niche not realized in the modern climate space with the ers method we expanded modern pollen climate relationships by mirroring pollen abundances for each taxon around a mode defined with respect to four climate axes mean winter temperature mean summer temperature mean winter precipitation and mean summer precipitation the ers method reconstructed past temperatures and precipitation during the height of no analogue conditions 14 160 12 370 cal yr bp for 37 of the crystal lake samples where techniques that employed only modern observational data found matches for only 13 of the fossil samples the total climate space of the expanded taxa set allowed analogue matches under more seasonal than present climates with higher than present precipitation the ers climate reconstructions for the height of no analogue conditions indicated cooler than present summer and winter temperatures similar to present seasonal range in temperatures higher than present winter precipitation and similar to present summer precipitation these results thus suggest that high moisture availability helped drive the formation of the midwestern no analogue communities with high fraxinus nigra abundances but do not show higher than present temperature seasonality notwithstanding the higher than present insolation seasonality at this time during the no analogue late glacial interval picea mariana f nigra and larix stands probably grew on low lying poorly drained soils in the crystal lake region whereas abies picea glauca quercus and ostrya carpinus grew on upland positions with better soil drainage

vegetation response to abrupt climate changes in western europe from 45 to 14 7k cal a bp the bergsee lacustrine record black forest germany

terrestrial cosmogenic argon cosmogenically enriched 38 ar 36 ar ratios are detectable in ca bearing terrestrial samples and are resolvable from a uniform background value of 0 18826 0 00018 for materials lacking nucleogenic or kinetic mass fractionation effects relationships between 38 ar 36 ar and cosmogenic 3he in apatite and fluorite are systematic but difficult to reconcile with current estimates of terrestrial production rates for 38 ar and 36 ar from ca suggesting that production from cl and or other targets is significant or that the estimates are inaccurate in either case the effects of time varying production of 36 ar from decay of cosmogenic 36 cl produced from ca k or cl on the 38 ar 36 ar ratio must be accounted for

quantitative holocene climatic reconstructions for the lower yangtze region of china quantitative proxy based and high resolution palaeoclimatic datasets are scarce for the lower reaches of the yangtze river lyr basin this region is in a transitional vegetation zone which is climatologically sensitive and as a birthplace for prehistorical civilization in china it is important to understand how palaeoclimatic dynamics played a role in affecting cultural development in the region we present a pollen based and regionally averaged holocene climatic twin dataset for mean total annual precipitation pann and mean annual temperature tann covering the last 10 000 years for the lyr region this is based on the technique of weighted averaging partial least squares regression to establish robust calibration models for obtaining reliable climatic inferences the pollen based reconstructions generally show an early holocene climatic optimum with both abundant monsoonal rainfall and warm thermal conditions and a declining pattern of both pann and tann values in the middle to late holocene the main driving forces behind the holocene climatic changes in the lyr area are likely summer solar insolation associated with tropical or subtropical macro scale climatic circulations such as the intertropical convergence zone itcz western pacific subtropical high wpsh and el nino southern oscillation enso regional multi proxy comparisons indicate that the holocene variations in precipitation and temperature for the lyr region display an in phase relationship with other related proxy records from southern monsoonal china and the indian monsoon influenced regions but are inconsistent with the holocene moisture or temperature records from northern monsoonal china and the westerly dominated region in northwestern china overall our comprehensive palaeoclimatic dataset and models may be significant tools for understanding the holocene asian monsoonal evolution and for anticipating its future dynamics in eastern asia

the climate of europe 6000 years ago palaeoclimates across europe for 6000 y bp were estimated from pollen data using the modern pollen analogue technique constrained with lake level data the constraint consists of restricting the set of modern pollen samples considered as analogues of the fossil samples to those locations where the implied change in annual precipitation minus evapotranspiration p e is consistent with the regional change in moisture balance as indicated by lakes an artificial neural network was used for the spatial interpolation of lake level changes to the pollen sites and for mapping palaeoclimate anomalies the climate variables reconstructed were mean temperature of the coldest month tc growing degree days above 5 c gdd moisture availability expressed as the ratio of actual to equilibrium evapotranspiration and p e the constraint improved the spatial coherency of the reconstructed palaeoclimate anomalies especially for p e the reconstructions indicate clear spatial and seasonal patterns of holocene climate change which can provide a quantitative benchmark for the evaluation of palaeoclimate model simulations winter temperatures tc were 1 3 k greater than present in the far n and ne of europe but 2 4 k less than present in the mediterranean region summer warmth gdd was greater than present in nw europe by 400 800 k day at the highest elevations and in the alps but 400 k day less than present at lower elevations in s europe p e was 50 250 mm less than present in nw europe and the alps but was 10 15 greater than present in s europe and p e was 50 200 mm greater than present in s and e europe

heterogeneous vegetation sensitivity at local and regional scales implications for pollen based climate reconstruction abstract vegetation climate relationships are often different at varying spatial scales which is seldom taken into account in reconstructing past climate changes from fossil pollen spectra represent more local vegetation composition but using regional or extra regional modern pollen climate calibration set in this paper we employ 2620 surface pollen spectra and six pollen sequences from continental east asia to reconstruct holocene climate with modern analogue technique a novel data set of vegetation sensitivity index vsi is introduced to examine vegetation climate relationships in 0 5 search windows around the fossil sites local and in the tailored calibration sets regional then we compare them to the explanatory abilities of reconstructed climate variables on explaining the pollen variance in calibration sets and in the fossil pollen data sets using constrained ordination cross validation and significance test by this procedure that we called local regional fossil comparison we can better determine which variable reconstruction is valid and useful in our cases moisture variable reconstructions in temperate forest steppe ecotone at the east asian summer monsoon margin are reliable consistent holocene moisture variations with a strong monsoon influence during 8 6 4 0 cal ka bp which can help us to better interpret human adaptations along the great wall however quantitative climate reconstructions at some sites are less reliable due to highly heterogeneous vegetation sensitivities surrounding the site particularly for areas with complicated topographical contexts we stress that vegetation sensitivities at local and regional scales both need to be investigated before conducting quantitative climate reconstruction

early to mid holocene forest line and climate dynamics in southern scandes mountains inferred from contrasting megafossil and pollen data the result of 344 radiocarbon dated megafossils is here presented and discussed this study aims at elucidating early to mid holocene forest line and climate dynamics in the southern scandes along

holocene temperature changes in northern fennoscandia reconstructed from chironomids using bayesian modelling the recently developed bayesian multinomial calibration model bummer was applied to the fossil chironomid assemblages of a lake situated at the present tree line in northern fennoscandia to reconstruct patterns in holocene climates the results are compared with inferences derived using non bayesian weighted averaging partial least squares regression the reconstruction exhibits both long term trends as well as a series of shorter term oscillations abrupt climatic excursions were particularly characteristic for the early holocene period with cooling episodes around 9200 8600 and 8200 cal yr bp the interval from ca 8000 to 5800 cal yr bp appeared to be warm and stable but was followed by a pronounced climatic cooling around 5800 cal yr bp leading to a relatively long lasting mid holocene temperature minimum between ca 5800 and 4000 cal yr bp the reconstruction during the latter part of the holocene is relatively featureless which may partly be due to gradual shallowing of the lake by sedimentation that may have affected chironomid compositions thereby masking the climate signal the major climatic patterns in our reconstruction agree well with inferences from greenland ice and marine sediments and are also in line with the previous reconstructions based on diatoms and pollen from the same core although the finer scale variations reflected by the three proxies do not always match the overall results provide evidence for climatic complexity during the holocene epoch and demonstrate that bayesian modelling is highly suitable for reconstruction purposes

a 11 000 yr palaeotemperature reconstruction from the southern boreal zone in finland abstract the ecotone between the boreo nemoral hemiboreal and the southern boreal vegetation zones constitutes the northern distributional limit of a number of thermophilous tree species in northern europe and is to a large extent controlled by climatic conditions we present a quantitative annual mean temperature reconstruction from a high resolution pollen stratigraphy in southern boreal finland using a pollen climate calibration model with a cross validated prediction error of 0 9 c our model reconstructs low but steadily rising annual mean temperature from 10 700 to 9000 cal yr bp at 8000 4500 cal yr bp reconstructed annual mean temperature reaches a period of highest values holocene thermal maximum with particularly high temperatures 2 0 1 5 c higher than at present at 8000 5800 cal yr bp from 4500 cal yr bp to the present day reconstructed annual mean temperature gradually decreases by ca 1 5 c comparison of present results with palaeotemperature records from the greenland ice cores notably with the northgrip 18 o record shows marked similarities suggesting parallel large scale holocene temperature trends between the north atlantic and north european regions the verification of the occurrence timing and nature of the short term temperature fluctuations during the holocene in the southern boreal zone in europe requires replicate high resolution climate reconstructions from the region

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

lunar tidal winds at adelaide and saskatoon at 80 to 100 km heights 1985 1990 winds data from the two sites were analyzed for lunar tides in 2 year groups the variation with height of the phase and amplitude of the tide showed considerable variability from year to year yet in general seasonal variations at particular heights were similar to those determined previously phases of the tide at the two sites were compared in order to estimate whether the tide was symmetric or antisymmetric for this purpose it was found necessary to use only 1 year data sets the predominance of symmetric tides during solstice months and antisymmetric tides at the equinox came as a surprise yet the result is in broad agreement with phase relations of the lunar geomagnetic tide

reconstructing palaeoclimatic variables from fossil pollen using boosted regression trees comparison and synthesis with other quantitative reconstruction methods abstract we test and analyse a new calibration method boosted regression trees brts in palaeoclimatic reconstructions based on fossil pollen assemblages we apply brts to multiple holocene and lateglacial pollen sequences from northern europe and compare their performance with two commonly used calibration methods weighted averaging regression wa and the modern analogue technique mat using these calibration methods and fossil pollen data we present synthetic reconstructions of holocene summer temperature winter temperature and water balance changes in northern europe highly consistent trends are found for summer temperature with a distinct holocene thermal maximum at ca 8000 4000 cal a bp with a mean t jja anomaly of ca 0 7 c at 6 ka compared to 0 5 ka we were unable to reconstruct reliably winter temperature or water balance due to the confounding effects of summer temperature and the great between reconstruction variability we find brts to be a promising tool for quantitative reconstructions from palaeoenvironmental proxy data brts show good performance in cross validations compared with wa and mat can model a variety of taxon response types find relevant predictors and incorporate interactions between predictors and show some robustness with non analogue fossil assemblages

quantitative summer and winter temperature reconstructions from pollen and chironomid data between 15 and 8 ka bp in the baltic belarus area abstract new pollen based reconstructions of summer may to august and winter december to february temperatures between 15 and 8 ka bp along a s n transect in the baltic belarus bb area display trends in temporal and spatial changes in climate variability these results are completed by two chironomid based july mean temperature reconstructions the magnitude of change compared with modern temperatures was more prominent in the northern part of bb area the 4 c winter and 2 c summer warming at the start of gi 1 was delayed in the bb area and lateglacial maximum temperatures were reached at ca 13 6 ka bp being 4 c colder than the modern mean the younger dryas cooling in the area was 5 c colder than present as inferred by all proxies in addition our analyses show an early holocene divergence in winter temperature trends with modern values reaching 1 ka earlier 10 ka bp in southern bb compared to the northern part of the region 9 ka bp

minimizing the edge effect in environmental reconstructions by trimming the calibration set chironomid inferred temperatures from spitsbergen a core from lake skardtjorna on western spitsbergen was analysed for subfossil chironomids with the aim of inferring past temperatures the core spans the last 1760 years and has a low concentration and low diversity of chironomids three taxa dominate the record oliveridia tricornis micropsectra radialistype and m insignilobus type the latter not previously recorded on svalbard compared with the full norwegian modern climate chironomid calibration data set skardtjorna is at the coldest end of the modern temperature gradient in an attempt to decrease potential bias caused by the numerical edge effect and to improve the taxon response functions the training set was trimmed by excluding lakes dissimilar to the study site two trimming approaches are tested in the first lakes at the warm end of the gradient are excluded in the second the calibration data set lakes are partitioned by twinspan on the basis of their modern chironomid assemblages and lakes most dissimilar to skardtjorna are exclude

quantitative interpretation of fossil pollen spectra dissimilarity coefficients and the method of modern analogs abstract dissimilarity coefficients measure the difference between multivariate samples and provide a quantitative aid to the identification of modern analogs for fossil pollen samples how eight coefficients responded to differences among modern pollen samples from eastern north america was tested these coefficients represent three different classes 1 unweighted coefficients that are most strongly influenced by large valued pollen types 2 equal weight coefficients that weight all pollen types equally but can be too sensitive to variations among rare types and 3 signal0to noise coefficients that are intermediate in their weighting of pollen types the studies with modern pollen allowed definition of critical values for each coefficient which when not exceeded indicate that two pollen samples originate from the same vegetation region dissimilarity coefficients were used to compare modern and fossil pollen samples and modern samples so similar to fossil samples were found that most of three late quaternary pollen diagrams could be reconstructed by substituting modern samples for fossil samples when the coefficients indicated that the fossil spectra had no modern analogs then the reconstructed diagrams did not match all aspects of the originals no modern analogs existed for samples from before 9300 yr b p at kirchner marsh minnesota and from before 11 000 yr b p at wintergreen lake michigan but modern analogs existed for almost all holocene samples from these two sites and brandreth bog new york

last glacial maximum climate of the former soviet union and mongolia reconstructed from pollen and plant macrofossil data an improved concept of the best analogues method was used to reconstruct the last glacial maximum lgm climate from a set of botanical records from the former soviet union and mongolia terrestrial pollen and macrofossil taxa were grouped into broad classes plant functional types pfts defined by the ecological and climatic parameters used in the biome1 model pft scores were then calibrated in terms of modern climate using 1245 surface pollen spectra from eurasia and north america in contrast to individual taxa which exhibit great variability and may not be present in the palaeoassemblages even in suitable climates pfts are more characteristic of the vegetation types the modified method thus allows climate reconstruction at time intervals with partial direct analogues of modern vegetation e g the lgm at 18 kbp mean temperatures were 20 29 degrees c colder than today in winter and 5 11 degrees c colder in summer in european russia and ukraine sites from western georgia show negative but moderate temperature anomalies compared to today 8 11 degrees c in january and 5 7 degrees c in july lgm winters were 7 15 degrees c colder and summers were 1 7 degrees c colder in siberia and mongolia annual precipitation sums were 50 750 mm lower than today across northern eurasia suggesting a weakening of the atlantic and pacific influences reconstructed drought index shows much drier lgm conditions in northern and mid latitude russia but similar to or slightly wetter than today around the black sea and in mongolia suggesting compensation of precipitation losses by lower than present evaporation

quantitative precipitation estimates for the northeastern qinghai tibetan plateau over the last 18 000 years quantitative information regarding the long term variability of precipitation and vegetation during the period covering both the lateglacial and the holocene on the qinghai tibetan plateau qtp is scarce herein we provide new and numerical reconstructions for annual mean precipitation pann and vegetation history over the last 18 000 years using high resolution pollen data from lakes dalianhai and qinghai on the northeastern qtp hitherto five calibration techniques including weighted averaging wa weighted average partial least squares regression wa pls modern analogue technique mat locally weighted weighted averaging regression lwwa and maximum likelihood ml were firstly employed to construct robust inference models and to produce reliable pann estimates on the qtp the biomization method was applied for reconstructing the vegetation dynamics the study area was dominated by steppe and characterized with a highly variable relatively dry climate at 18 000 11 000 cal a b p pann increased since the early holocene obtained a maximum at 8000 3000 cal a b p with coniferous temperate mixed forest as the dominant biome and thereafter declined to present the pann reconstructions are broadly consistent with other proxy based paleoclimatic records from the northeastern qtp and the northern region of monsoonal china the possible mechanisms behind the precipitation changes may be tentatively attributed to the internal feedback processes of higher latitude e g north atlantic and lower latitude e g subtropical monsoon competing climatic regimes which are primarily modulated by solar energy output as the external driving force these findings may provide important insights into understanding the future asian precipitation dynamics under the projected global warming

pollen based palaeoclimate reconstructions over long glacial interglacial timescales methodological tests based on the holocene and mis 5d c deposits at sokli northern finland palaeoclimatic reconstructions over long glacial interglacial timescales present major methodological challenges as calibration methods based on modern climate and vegetation patterns may yield biased reconstructions from non analogue palaeoclimates such as severely continental glacial periods in this work we present pollen based summer temperature reconstructions based on holocene and early weichselian marine isotope stages mis 5d c deposits at sokli northern finland we attempt to improve the robustness of reconstructions of continental palaeoclimates by using two calibration sets with one located in the region surrounding the fossil site and another in a more continental region in northwestern russia we assess the reliability of the reconstructions by estimating the compositional fit between fossil and calibration samples and by comparison with independent plant macrofossil based reconstructions we find the fossil samples to fit the extra regional high continentality calibration set better during the early holocene and mis 5d c especially in mis 5d c however even the high continentality calibration set fits the fossil samples poorly compared to the fit achieved in the mid and late holocene thus our results highlight the problem of finding applicable calibration data for pre holocene periods we finally discuss the relative strengths and vulnerabilities of different calibration methods in reconstruction of non analogue palaeoclimates copyright 2013 john wiley sons ltd

climatic evolution during the middle pleistocene warm period of bilshausen germany compared to the holocene abstract middle pleistocene warm periods are particularly useful for comparison with our present warm period one of them marine isotope stage mis 11 has been considered a potential analogue for the holocene whereas older interglacials e g mis 13 are distinctly different however terrestrial middle pleistocene sites other than the holsteinian and quantitative climate reconstructions for this period are very rare in europe a unique terrestrial site in north central europe is known from bilshausen germany the sediments are varved and indicate that this interglacial lasted 25 000 years more than twice as long as the holocene so far the warm period probably correlates to mis 11 or possibly to mis 13 a new palynological investigation with large pollen counts is presented which forms the basis for quantitative temperature reconstructions based on the probabilistic indicator taxa approach the so called pdf method the range of tree species that formed the vegetation during the bilshausen warm period is reminiscent of the holocene but the vegetational as well as the reconstructed climatic development shows distinct differences no pronounced initial successional phase is recorded in the pollen stratigraphy from bilshausen in addition a mesocratic or optimum phase of forest development as in the holocene is unclear in the bilshausen sequence reconstructed temperature values are several c lower than holocene temperatures for most of the bilshausen interglacial only for several millennia in the late phase of the bilshausen interglacial were july temperatures higher than the holocene july temperatures seasonality was much stronger during the bilshausen interglacial and the temperature trends differ between the two interglacials likely reasons for the pronounced differences are on one hand global temperature insolation changes and atmospheric circulation on the other hand more regional factors such as the configuration of the north sea basin may also be responsible for the colder winter temperatures and stronger seasonality during the bilshausen interglacial compared to the holocene reliable absolute dating of the bilshausen interglacial is needed which would allow a more detailed evaluation of the forcing factors that determined the climate during the bilshausen interglacial

a high mountain pollen altitude calibration set for palaeoclimatic use in the tropical andes the numerical relationship between modem pollen assemblages and altitude in high mountain environments from the northern andes is analysed in order to found inference models that allow estimating palaeoaltitudes and palaeotemperatures from past pollen records the calibration set dm consists of a 50 sample altitudinal transect between 2300 and 4600 m altitude the overall and individual pollen responses to altitude were tested by correspondence analysis ca generalized linear regression hof and weighted averaging wa transfer functions were derived by weighted averaging partial least squares wa pls regression overall altitude is the main controlling factor for the composition of pollen assemblages as shown by the high correlation between altitude and the first ca component r 0 88 individually around 35 of the 82 pollen taxa show a significant response to altitude through monotonic or unimodal functions the best transfer function obtained has a good statistical performance as shown b

10000 years of interannual sedimentation recorded in the lake nautajarvi finland clastic organic varves abstract physical properties of varves formed over the last ca 10 000 years from lake nautajarvi central southern finland provide a potential proxy record of winter precipitation and temperature via catchment runoff and erosion the seasonal scale varved data indicate that the winter severity and duration of summer growing season has changed considerably during the holocene in southern central finland periods of increased catchment erosion occurred at 7590 7530 bc 7450 7400 bc 7220 7110 bc 7000 6000 bc 5400 5200 bc 4400 4000 bc 2700 2400 bc ca 1500 bc to ad 500 and 1400 ad onwards the observed changes are likely related to severe winters conditions with high net accumulation of snow between ca 7500 bc and ad 300 whereas ad 300 onwards an increasing agricultural input is seen in the varve and pollen data periods that can be interpreted as indicating attenuated spring floods caused by milder and wetter winters appeared around 7000 bc and ad 1000 ad 1200 the latter corresponding with the last historically recorded warm interval in europe known as the medieval climate anomaly

low frequency and high frequency changes in temperature and effective humidity during the holocene in south central sweden implications for atmospheric and oceanic forcings of climate an integrated use of independent palaeoclimatological proxy techniques that reflect different components of the climate system provides a potential key for functional analysis of past climate changes here we report a 10 000 year quantitative record of annual mean temperature tann based on pollen climate transfer functions and pollen stratigraphical data from lake flarken south central sweden the pollen based temperature reconstruction is compared with a reconstruction of effective humidity as reflected by a 18o record obtained on stratigraphy of lacustrine carbonates from lake igelsjon c 10 km from lake flarken which gives evidence of pronounced changes in effective humidity the relatively low tann and high effective humidity as reflected by a low evaporation inflow ratio suggest a maritime early holocene climate 10 000 8 300 cal year bp seemingly incompatible with the highly seasonal solar insolation configuration we argue that the maritime climate was due to the stronger than present zonal flow enhanced by the high early holocene sea surface temperatures in the north atlantic the maritime climate mode was disrupted by the abrupt cold event at 8 200 cal year bp followed at 8 000 cal year bp by a stable holocene thermal maximum the latter was characterized by tann values about 2 5 c higher than at present and markedly dry conditions indicative of stable summer time anti cyclonic circulation possibly corresponding with modern blocking anticyclonic conditions the last 4 300 year period is characterized by an increasingly cold moist and unstable climate the results demonstrate the value of combining two independent palaeoclimatic proxies in enhancing the reliability generality and interpretability of the palaeoclimatic results further methodological refinements especially in resolving past seasonal climatic contrasts are needed to better understand the role of different forcing factors in driving millennial scale climate dynamics

microfossils from coastal environments as indicators of paleo earthquakes tsunamis and storms abstract coastal risk assessment and hazard mitigation require datasets on centennial and millennial temporal scales to capture natural variability and multiple occurrences of the largest but least frequent events coastal sediments from low energy depositional environments archive geologic evidence of paleo earthquakes tsunamis and storms many of the best reconstructions of these events are derived from changes in microfossil diatoms foraminifera and pollen assemblages in this review we explain how microfossils are used to reconstruct records of paleoearthquakes by quantifying the amount of coseismic and interseismic vertical land movements along tectonically active coastlines examples from the united states alaska and the pacific northwest japan and chile show that microfossil based transfer functions may provide continuous records of vertical land movement during earthquake deformation cycles we discuss how microfossil habitat preferences and taphonomic character are used to constrain sediment provenance e g beach nearshore or offshore sources and identify overwash deposits and how this information can be used to reconstruct the recurrence of tsunamis and storms analysis of overwash deposits from thailand and malaysia indicates the ability of microfossils to resolve individual waves within tsunami sediments and an example from the sendai coastal plain in japan uses foraminifera to ascribe a beach to nearshore provenance for the 2011 tohoku tsunami deposit finally we present recent examples from the gulf of mexico on the use of foraminifera to estimate the volume and distance of transport of storm overwash from hurricanes

cosmic ray production rates of 10be and 26al in quartz from glacially polished rocks we have studied the concentrations of 10be and 26al in quartz crystals extracted from glacially polished granitic surfaces from the sierra nevada range these surfaces were identified with the glacial advance during the tioga period 11 000 years ago our measurements yield the most accurate estimates to date for the absolute production rates of these nuclides in sio2 due to cosmic ray nucleons and muons for geomagnetic latitudes 43 8 44 6 n and altitudes 2 1 3 6 km the estimates are relatively free from uncertainties in snow cover since we studied a suite of rock surfaces inclined 0 75 with respect to the horizontal the principal uncertainty arises due to the lack of a precise date for the glacial retreat event about 10 the 26al 10be ratio at production 6 0 is determined more accurately since the exposure age of the samples is 2 orders of magnitude smaller than the mean lives of the two nuclides production rates of 10be and 26al in quartz at other latitudes and altitudes in the troposphere can be determined from the present measurements by scaling using the known altitude and latitude dependence of cosmic ray fluxes of nucleons and negative muons knowledge of the production rates of these nuclides is a prerequisite for their application in erosion and geomorphological studies

the effect of calibration data set selection on quantitative palaeoclimatic reconstructions quantitative palaeoclimatic reconstructions based on biological fossils are a major source of information on long term climatic variability such reconstructions typically use some kind of a modern calibration data set describing the variation of the studied biological group in present day climate space here we explore the effect of calibration data set selection on palaeoclimatic reconstructions by creating alternate calibration data sets via stratified random sampling to reconstruct mean july temperature tjul for four fossil pollen sequences from northern europe we show that palaeoclimatic reconstructions using methods based on taxon response models can be highly sensitive to the calibration data set used in particular the absolute reconstructed temperatures show great sensitivity to calibration data selection which suggests that the absolute values of palaeoclimatic reconstructions may not be robust by contrast we find the relative shapes of the reconstructed curves to be more robust to cali

holocene seasonality changes in the central mediterranean region reconstructed from the pollen sequences of lake accesa italy and tenaghi philippon greece this study presents pollen based climate reconstructions of holocene temperature and precipitation seasonality for two high resolution pollen sequences from the central lake accesa central italy and eastern mediterranean tenaghi philippon greece regions the quantitative climate reconstruction uses multiple methods to provide an improved assessment of the uncertainties involved in palaeoclimate reconstructions the multimethod approach comprises partial least squares regression weighted average partial least squares regression the modern analogues technique and the non metric multidimensional scaling generalized additive model method we find two distinct climate intervals during the holocene the first is a moist period from 9500 to 7800 cal bp characterised by wet winters and dry summers resulting in a strongly seasonal hydrological contrast stronger than today that is interrupted by a short lived event around 8200 cal bp this event is characterised by wet winters and summers at accesa wh

climate in northern eurasia 6000 years ago reconstructed from pollen data using a climatic calibration based on the scores of the plant functional types pfts calculated for 1245 surface pollen spectra the climate at 6 ka bp has been reconstructed for a set of 116 pollen spectra from the former soviet union and mongolia the results are presented as maps of climatic anomalies and maps of probability classes showing the significance of these differences from the modern climate the reconstructed patterns are spatially coherent but have confidence levels that vary from region to region due to the often large error ranges at 6 ka the winters were more than 2oc warmer than today north of 50on with a high significance east of the urals summers were also more than 2oc warmer than today with a high level of confidence north of the polar circle and in central mongolia in the mid latitudes of siberia in northern kazakhstan and around the black and the caspian seas 6 ka summers were significantly cooler than today the reconstructed moisture availability ratio of actual to equilibrium evapotranspiration was more than 10 higher than today in the ukraine southern russia and northern mongolia and more than 10 lower than today in central mongolia this pattern corresponds partly with that of the water budget annual precipitation minus evaporation reconstructed from lake level records 1999 elsevier science b v all rights reserved