characterizing changes in the sedimentary environment of a varved lake sediment record in southern central finland around 8000 cal yr bp the varved lake sediment record of lake nautajarvi in southern central finland indicates fluctuations in the annual sedimentation pattern and lake environment around 8000 cal yr bp annual accumulation of catchment derived mineral matter peaks a number of times and there are changes in the deposition rate of organic matter based on evidence from the lake nautajarvi sediment record the climate was characterised by a millennial scale colder period that terminated at one or several cooling events around 8000 cal yr bp during one of these events diatom composition undergoes a change from planktonic species dominance to more littoral species dominance at 8160 cal yr bp and a recovery around 8010 cal yr bp the timing of this 150 year long diatom anomaly is convergent with increased catchment erosion and decreased organic matter accumulation we interpret that during such a period the environment was characterised by colder winter temperatures prolonged duration of ice cover higher than normal spring discharge and rapid development of thermal stratification in the spring coupled with reduced water circulation and shorter growing seasons copyright 2008 john wiley sons ltd

integrated varve and pollen based temperature reconstruction from finland evidence for holocene seasonal temperature patterns at high latitudes a detailed understanding of decadal to millennial scale climate changes requires seasonal scale summer winter reconstructions of past precipitation and temperature fluctuations comparing seasonally resolved varve records with pollen based sum of growing degree days gdd reconstructions from lake nautajarvi we examined the intra annual nature of climate variability in central southern finland during the holocene the organic varve record and the gdd reconstruction show roughly comparable trends supporting the interpretation that both proxies predominantly reflect summer temperatures in the study area the records suggest low but rising early holocene 9500 to 8500 cal yr bp summer temperatures the holocene thermal maximum htm in the gdd record dates to about 7500 to 4500 cal yr bp but the organic varve record along with reconstructed changes in vegetation composition notably a peak of tilia pollen percentages indicate that during the htm there was a trend towards a more continental climate with maximum mid summer temperatures reached at 6500 to 4500 cal yr bp both records reflect the start of the post htm cooling at about 4500 cal yr bp simultaneously with an increase of the amount of catchment erosion and mineral matter influx into the lake suggesting gradually colder and or longer winters with high net accumulation of snow the organic varve record and the gdd record start to diverge at 2000 cal yr bp possibly owing to the human influence on catchment processes the reconstructed mid holocene summer temperature peak deviates from the regional climate model outputs which suggest highest summer temperatures during the early holocene

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

periodicity of climate conditions and solar variability derived from dendrochronological and other palaeoclimatic data in high latitudes abstract the periodicity of climatic processes in the barents sea region and along the arctic ocean coast during several hundred years has been studied by analyzing the tree ring chronologies for the regions close to the northern timberline in the barents sea region cyclicities of climatic processes with periods of around 90 30 35 22 23 18 and 11 12 years have been established by spectral analysis of the data for the kola peninsula wavelet analysis of annual series of conifer tree rings generalized for 10 regions along the northern timberline from the kola peninsula to chukotka for the period 1458 1975 has revealed the same periodicities for the vast areas of northern russia climatic cyclicity with a period of about 35 years is known as the bruckner cycle climatic cycles with periods of around 90 22 23 and 11 12 years correlate well with the corresponding solar activity cycles a possible solar forcing of periodic climatic processes and its nonlinear influence on the atmosphere ocean continental system are discussed

teleconnections between the subtropical monsoons and high latitude climates during the last deglaciation the major deglacial intensification of the southwest monsoon occurred at 11 450 150 calendar years before present synchronous with a major climate transition as recorded in greenland ice an earlier event of monsoon intensification at 16 000 150 calendar years before present occurred at the end of heinrich layer 1 in the atlantic and parallels the initial rise in global atmospheric methane concentrations and the first abrupt climate changes in the antarctic thus the evolution of the monsoonal and high latitude climates show teleconnections but hemispheric asymmetries superimposed on abrupt events the monsoonal climate shows high frequency variability of 1785 1450 and 1150 year oscillations and abrupt climate change seems to occur when at least two of these oscillations are in phase

a 2000 year record of solar forcing on varved lake sediment in eastern finland abstract a high resolution study was performed on varved sediments from lake lehmilampi in eastern finland varve data was collected by digital image analysis using standard 1 8 mm thick samples impregnated in epoxy and x rayed climatic variability is imprinted on varve properties varve thickness and accumulation of mineral and organic matter during the last 2000 years the cumulative counting error of the varve record is estimated as 2 3 qualitative comparison of varve parameters and residual 14c constructed from tree rings revealed close correspondence between the two records suggesting solar forcing on lake sedimentation classical climatic periods of the last millennia medieval climate anomaly 1060 1280 in the varve record and little ice age cooler phases culminating in 1340 1465 1545 1680 1850 and also in 1930 in the varve record are clearly evident in the varve record at present the physical link between solar activity levels and lake sedimentation has not been established

multicentennial scale hydrological changes in the black sea and northern red sea during the holocene and the arctic north atlantic oscillation 1 paleoenvironmental proxy data for ocean properties eolian sediment input and continental rainfall based on high resolution analyses of sediment cores from the southwestern black sea and the northernmost gulf of aqaba were used to infer hydroclimatic changes in northern anatolia and the northern red sea region during the last 7500 years pronounced and coherent multicentennial variations in these records reveal patterns that strongly resemble modern temperature and rainfall anomalies related to the arctic oscillation north atlantic oscillation ao nao these patterns suggest a prominent role of ao nao like atmospheric variability during the holocene beyond interannual to interdecadal timescales most likely originating from solar output changes

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

documentation of the physical properties of annually laminated varved sediments at a sub annual to decadal resolution for environmental interpretation this paper describes a method to digitize high resolution physical properties of annually laminated lake sediments we modified a water acetone epoxy exchange method in order to preserve all the fine structural details that varved sequences provide by applying sediment microstratigraphical investigations x ray radiography sem and semi automatic image analysis we were able to establish detailed information about varve composition and structure mineral magnetic measurements were also applied for comparison by comparing all available physical data at high resolution it will be possible to identify environmental changes that has occurred in the lake drainage basin

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

interdecadal variations of the thermohaline circulation in a coupled ocean atmosphere model abstract a fully coupled ocean atmosphere model is shown to have irregular oscillations of the thermohaline circulation in the north atlantic ocean with a time scale of approximately 50 years the irregular oscillation appears to be driven by density anomalies in the sinking region of the thermohaline circulation approximately 52 n to 72 n combined with much smaller density anomalies of opposite sign in the broad rising region the spatial pattern of see surface temperature anomalies associated with this irregular oscillation bears an encouraging resemblance to a pattern of observed interdecadal variability in the north atlantic the anomalies of sea surface temperature induce model surface air temperature anomalies over the northern north atlantic arctic and northwestern europe

interpretation paleoecologique et relations biogeographiques de la faune de vertebrees du miocene superieur d injana irak abstract the discovery of new fossils in the late miocene of injana jebel hemrin iraq enables us to complete the injana vertebrate faunal list which now includes 25 vertebrate taxa 19 of them belonging to mammals the injana paleoenvironment corresponds to a vast fluviatile system where under hot and wet conditions there existed a mosaic of landscapes ranging from grassland to woodland and forest with swampy zones it is similar to that of the middle siwaliks of the indian subcontinent and differs from that of the irano turkish plateau the injana fauna fo iraq established the existence during the late miocene of a biogeographical area which had preferential links with the indian subcontinent in the east and africa in the west this area was more or less isolated from the adjacent northern regions irano turkish plateau by the southern branch of the asian alpine range taurids and zagrids this acted as a geographical barrier which many vertebrates did not cross

the influence of the de vries 200 year solar cycle on climate variations results from the central asian mountains and their global link long term climatic changes related to solar forcing were examined using millennium scale palaeoclimatic reconstructions from the central asian mountain region i e summer temperature records for the tien shan mountains and precipitation records for the tibetan plateau the reconstructions were based on juniper tree ring width records i e juniperus turkestanica for the tien shan and sabina przewalskii for the tibetan plateau the data were processed using spectral and wavelet analysis and filtered in the frequency range related to major solar activity periodicities the results obtained for various tree ring chronologies indicate palaeoclimatic oscillations in the range of the de vries similar to 210 year solar cycles through the last millennium the quasi 200 year variations revealed in the palaeoclimatic reconstructions correlate well r 2 0 58 0 94 with solar activity variations delta c 14 variations the quasi 200 year climatic variations have also been detected in climate linked processes in asia europe north and south america australia and the arctic and antarctica the results obtained point to a pronounced influence of solar activity on global climatic processes analysis has shown that climate response to the long term global solar forcing has a regional character an appreciable delay in the climate response to the solar signal can occur up to 150 years in addition the sign of the climate response can differ from the solar signal sign the climate response to long term solar activity variations from 10s to 1000s years manifests itself in different climatic parameters such as temperature precipitation and atmospheric and oceanic circulation the climate response to the de vries cycle has been found to occur not only during the last millennia but also in earlier epochs up to hundreds of millions years ago c 2007 elsevier b v all rights reserved

holocene periodicity in north atlantic climate and deep ocean flow south of iceland climate fluctuations during the past millennium are relatively well documented1 on a longer timescale there is growing evidence of millennial scale variability of holocene climate at periodicities of 2 500 and 950 years possibly caused by changes in solar flux 2 3 and 1 500 years maybe related to an internal oscillation of the climate system 4 5 6 but the involvement of deep water masses in these holocene climate changes has yet to be established here we use sediment grain size data from the iceland basin to reconstruct past changes in the speed of deep water flow the study site is under the influence of iceland scotland overflow water isow the flow of which is an important component of the thermohaline circulation that modulates european climate flow changes coincide with some known climate events the little ice age and the mediaeval warm period and extend over the entire holocene epoch with aquasi periodicity of 1 500 years the grain size data indicate afaster isow flow when the climate of northern europe is warmer however a second mode of operation is observed in the early holocene when warm climate intervals are associated with slower isow flow at that time the melting remnant of land based glacial age ice may have provided a sufficient source of fresh water to the ocean to reduce isow flow south of iceland

magnetic data interpretation for the source edge locations in parts of the tectonically active transition zone of the narmada son lineament in central india the study has been carried out in the transition zone of the narmada son lineament nsl which is seismically active with various geological complexities upwarp movement of the mantle material into the crust through fault fractures lamination and upwelling nsl is one of the most prominent lineaments in central india after the himalaya in the indian geology the area of investigation extends from longitude 80 25 e to 81 50 e and latitude 23 50 n to 24 37 n in the central part of the indian continent different types of subsurface geological formations viz alluvial gondwana deccan traps vindhyan mahakoshal granite and gneisses groups exist in this area with varying geological ages in this study area tectonic movement and crustal variation have been taken place during the past time and which might be reason for the variation of magnetic field magnetic anomaly suggests that the area has been highly disturbed which causes the narmada son lineament trending in the ene wsw direction magnetic anomaly variation has been taken place due to the lithological variations subject to the changes in the geological contacts like thrusts and faults in this area shallow and deeper sources have been distinguished using frequency domain analysis by applying different filters to enhance the magnetic data various types of derivatives to identify the source edge locations of the causative source bodies the present study carried out the interpretation using total horizontal derivative tilt angle derivative horizontal tilt angle derivative and cos derivative map to get source edge locations the results derived from various derivatives of magnetic data have been compared with the basement depth solutions calculated from 3d euler deconvolution it is suggested that total horizontal derivative tilt angle derivative and cos derivative are the most useful tools for identifying the multiple source edge locations of the causative bodies in this tectonically active and transition zone area as this area is highly prone to hydrocarbon bearing zone hence the integrated interpretation could reliably image various thrusts and faults boundaries and the source edge locations with dip and strike orientation along with the basement lineation in encouraging exploration for better understanding of the geo scientific data

varve studies at hector lake alberta canada and the relationship between glacial activity and sedimentation glacial lake sedimentary records from hector lake in banff national park alberta are examined with the aim of clarifying the relationship between glacial activity and outwash sedimentation rhythmic couplets in lake bottom sediments provide a method for accurate documentation and dating of recent sedimentation chronology as analysis of 137cs content indicates that the couplets are of annual periodicity i e varves a comparison of sedimentation rate records with recent regional glacial history indicates that high sedimentation rates of one to a few decades duration occur either during and immediately following periods of moraine deposition ie maximum ice stands or during periods of rapid ice recession comparison of sedimentary records with somewhat longer term glacial and vegetation records indicates that sedimentation rate variations of several centuries duration closely parallel changes in upvalley ice extent over this time scale high sedimentation rates occur during periods of relatively increased ice extent low rates during periods of reduced ice extent within this general pattern however sedimentation rates may remain very high for nearly a century following maximum ice stands due to the exposure of unstable glaciogenic deposits to fluvial reworking during ice recession

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

a 725 yr cycle in the climate of central africa during the late holocene high resolution analyses of the chemical and stable isotope composition of endogenic calcite from lake edward an equatorial rift lake in central africa reveal large oscillations in african climate and moisture balance over the past 5400 yr these oscillations indicate a series of droughts from 4900 to 400 yr b p that define a drought period of 725 yr this period may be correlated to variations in the indian ocean monsoons as documented by similar periods in sea surface salinity records from the northern indian ocean the similarities in periodicity of the lake edward and indian ocean records may indicate that low frequency variability within the indian and pacific oceans dominates millennial scale african moisture balance and the holocene climate of the tropical indian ocean

holocene climate variability and periodicities in south central sweden as interpreted from peat humification analysis analysis of the decomposition of peat has been used to identify climatic shifts over the last 10 000 years in two raised bogs stomyren and kortlandamossen south central sweden age depth curves have been constructed using radiocarbon dates and tephra layers peat humification data have been subjected to spectral analyses using the lomb scargle fourier method and reveal a periodicity of c 250 years in both records cycles of c 200 yr and c 400 yr were found at stomyren and at kortlandamossen respectively these periodicities could correspond to changes in solar activity levels a test estimating the possible level of noise has been applied to the spectral analyses the humification indices indicate prominent shifts to wetter conditions at c 7500 4300 4200 3700 3500 and 2800 2400 cal yr bp the most distinct drier phases start at c 4500 and 3250 cal yr bp

characteristics of sedimentary varve chronologies a review abstract we constructed a varve data base vdb to study the worldwide distribution of varved sediment records and the fidelity of their varve chronologies clusters of lakes with varved sediments exist in central north america in the canadian arctic and in northern and central europe among the 108 sites included in the vdb varved records are typically 200 500 cm long and cover a period of 1000 2000 years their varve chronologies are often based on counting of annual layers from fresh sediment surfaces and photographs or from epoxy embedded sediment blocks and thin sections the vdb indicates that chronological errors associated with counting sedimentary varves fall generally between 1 and 3 but only 57 of published records are providing quantitative error estimations for their chronologies with a careful documentation of varves and by applying radiometric dating methods to surface sediments as well as using historical events as time markers there is the potential of having centennial long varved records with a very precise age depth control however it is unrealistic to expect errors significantly below 1 from several millennia long sections we found no indication that varve chronologies would have been substantially more accurate and precise in some parts of the world than in others or statistically dependent on varve thickness or temporal extension of a varved sequence according to the vdb close to 90 of the published varve chronologies have been cross checked with some independent dating methods

a 5000 yr record of climate change in varved sediments from the oxygen minimum zone off pakistan northeastern arabian sea the upper holocene marine section from a kasten core taken from the oxygen minimum zone off karachi pakistan at water depth 700 m contains continuously laminated sediments with a sedimentation rate of 1 2 mm yr and a unique record of monsoonal climatic variability covering the past 5000 years our chronostratigraphy is based on varve counts verified by conventional and ams 14 c dating individual hemipelagic varve couplets are about 0 8 1 5 mm thick with light colored terrigenous laminae a deposited mainly during the winter monsoon alternating with dark colored laminae b rich in marine organic matter coccoliths and fish debris that reflect deposition during the high productivity season of the late summer monsoon august october precipitation and river runoff appear to control varve thickness and turbidite frequency we infer that precipitation decreased in the river watershed indicated by thinning varves after 3500 4000 yr b p this is about the time of increasing aridification in the near east and middle east as documented by decreasing nile river runoff data and lake level lowstands between turkey and northwestern india this precipitation pattern continued until today with precipitation minima about 2200 1900 yr b p 1000 yr b p and in the late middle ages 700 400 yr b p and precipitation maxima in the intervening periods as documented by spectral analysis the thickness of varve couplets responds to the average length of a 250 yr cycle a 125 yr cycle the gleissberg cycle of solar activity 95 yr and a 56 yr cycle of unknown origin higher frequency cycles are also present at 45 39 29 31 and 14 yr the sedimentary gray value also shows strong variability in the 55 yr band plus a 31 yr cycle because high frequency cyclicity in the enso band ca 3 5 and 5 yr is only weakly expressed our data do not support a straightforward interaction of the pacific enso with the monsoon driven climate system of the arabian sea

complexity of holocene climate as reconstructed from a greenland ice core glaciochemical time series developed from summit greenland indicate that the chemical composition of the atmosphere was dynamic during the holocene epoch concentrations of sea salt and terrestrial dusts increased in summit snow during the periods 0 to 600 2400 to 3100 5000 to 6100 7800 to 8800 and more than 11 300 years ago the most recent increase and also the most abrupt coincides with the little ice age these changes imply that either the north polar vortex expanded or the meridional air flow intensified during these periods and that temperatures in the mid to high northern latitudes were potentially the coldest since the younger dryas event

stable isotope variations in stalagmites from northwestern sweden document climate and environmental changes during the early holocene this paper presents two early holocene 9 6 5 9 ka bp high resolution stable isotope records of stalagmites from two caves in northwestern sweden korallgrottan and labyrintgrottan close similarities between the swedish records and a previously presented norwegian stalagmite oxygen isotope record emphasize the potential of scandinavian stalagmites to provide high resolution regional palaeoclimatic information the stable oxygen isotope records are interpreted to reflect the temperature evolution during the early holocene with a gradual warming from c 9 6 ka bp interrupted by cooler conditions at 8 5 8 0 ka bp the results indicate that the cooler conditions were driven by two to three abrupt cold events rather than one 8 2 event only except for these cold events the stalagmite oxygen isotope records show that temperatures in northwestern sweden were warmer than today between 9 6 and 5 9 ka bp and that during this period the interval between 7 8 and 5 9 ka bp seems to have been the warmest the hig

testing the fidelity of sediment chronology comparison of varve and paleomagnetic results from holocene lake sediments from central finland abstract a careful construction of independent varve and paleomagnetic chronologies from three varved lake sediment records from central finland resulted in detailed and continuous age depth profiles cumulative varve calculation errors were estimated to be 3 for lake alimmainen savijarvi 10 295 340 varve years and 1 for lakes nautajarvi 9898 97 varve years and korttajarvi 9590 103 varve years paleomagnetic secular variation psv curves demonstrate good consistency between these sites and within a margin of varve chronology error they show similar declination and inclination features commonly described in the uk and sweden the timing of psv patterns from finnish varved sites agree well with uk curves between the present and 2000 bc and in pre 6000 bc deposits and with swedish data between the present and 5000 bc combined inclination records from three independently dated finnish varved sites possess an opportunity for accurate paleomagnetic comparisons within the margin of varve chronology errors and throughout the last 10 000 years

varve formation and the climatic record in an alpine proglacial lake calibrating annually laminated sediments against hydrological and meteorological data processes leading to the formation of varves in proglacial oeschinensee switzerland are investigated the aim is to calibrate annually laminated sediments of the last three decades against hydrological and meteorological instrumental data results from water samples and sediment traps show that the suspended sediment in the lake is mainly distributed by underflows during the time of the largest sediment input from may to mid august this leads to the deposition of the basal silt layers of the varves settling of fine grained suspension from interflows dominates sedimentation between august and october forming the final layer of fine grained material at the end of the annual deposition cycle the median grain size at the top of the varves is always below 5 m and thus defines the varve boundaries varve thickness is a function of the annual discharge of suspended load from the catchment this is supported by evidence from hydrological and meteorological data compiled for a glaciated catchment loetschen

holocene glacier variations in central jotunheimen southern norway based on distal glaciolacustrine sediment cores abstract sediment cores from two glacier fed lakes are used to reconstruct a continuous record of glacier variations since about 10 000 cal bp in the smorstabbtinden massif of central jotunheimen southern norway particular attention is paid to the century to millennial scale pre little ice age glacial signal based on an estimated temporal resolution of 55 and 25 yr cm 1 for bovertunsvatnet and dalsvatnet respectively visible lithostratigraphic variations organic content loss on ignition calcium carbonate content magnetic susceptibility and grain size fractions especially the fine silt are used as proxy indicators of glacier presence and extent in the lake catchments following deglaciation the early holocene was characterized by generally small glaciers until a major advance the finse event peaking at approximately 8200 cal bp from 7900 to at least 5300 cal bp glaciers appear to have been absent from central jotunheimen there is evidence of glacier expansion between about 2400 and 1600 cal bp the bovertun i event and between about 1400 and 800 cal bp the bovertun ii event before reduced glacier extent during the mediaeval warm period finally the most extensive neoglacial maximum occurred during the little ice age after 500 cal bp in addition to providing a record of the broad pattern of climatically forced holocene glacier variations periodicities at 110 140 200 285 and about 500 yr have been identified uncertainties remain concerning the precise timing of events glacierization and deglacierization detection thresholds a possible mid to late holocene 5300 2500 cal bp neoglacial build up of small glaciers and shorter term decadal to century scale variations in glacier size for which more proximal sites are required

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

effects of solar forcing and north atlantic oscillation on the climate of continental scandinavia during the holocene abstract 10 000 year long varved sediment records from lakes nautajarvi and korttajarvi finland provide evidence of climate and environment oscillations at multi decadal to millennial timescales we used two independent methods to extract periodic features from these time series of clastic laminae and assess their statistical reliability analyses revealed that seasonal sediment fluxes correspond to environmental changes with statistically significant periodicities of 1500 1800 1000 600 800 nearly 300 nearly 200 150 170 nearly 90 and 47 years showing variable coherency with different climate forcing factors and other palaeoproxy records in the northern hemisphere results indicate that the holocene winter climate in continental scandinavia was forced by a combination of several factors at least by solar variability and the north atlantic ocean atmosphere circulation patterns with varying influences through time