lateglacial vegetation development in denmark new evidence based on macrofossils and pollen from slotseng a small scale site in southern jutland abstract this paper presents the first unambiguous terrestrial palaeoecological record for the late glacial bolling warming in denmark pollen and macrofossil stratigraphies from pre bolling to 10 800 cal yr bp are presented from a small kettle hole in southwest denmark during which the lake basin developed from an immature stage after the deglaciation to complete infilling in the early holocene results show that the recently deglaciated landscape bore a discontinuous vegetation of pioneer plants after the bolling warming an open dryas octopetala betula nana community developed with helianthemum oelandicum subarctic species were dominant and local successions were probably delayed by relatively unstable and infertile soils there is no indication of a climate cooling during the period corresponding to the older dryas but the occurrence of several drought tolerant and steppe species indicates that the period was relatively dry in the allerod period the dryas b nana vegetation was initially replaced by an open salix and grass dominated vegetation and some 400 years later the first tree birches were documented presumably occupying moist and sheltered soils while drier land remained open in the younger dryas period trees disappeared and the vegetation became open again and dominated by subarctic species following climate warming at the younger dryas holocene transition a shrub community of empetrum and juniperus developed after approximately 200 years it was replaced by birch forest overall the late glacial vegetation cover had a more open and patchy character than inferred from previous pollen studies as assessment of the vegetation succession based on macrofossil evidence is essential the inferred general vegetation development corresponds well with results of other studies in the region canonical ordinations rda indicate that vegetation changes at the landscape scale during the lateglacial period were driven by changes in climate soils and competition for light

early holocene climate oscillations recorded in three greenland ice cores a new ice core chronology for the greenland dye 3 grip and ngrip ice cores has been constructed making it possible to compare the 18 o and accumulation signals recorded in the three cores on an almost annual scale throughout the holocene we here introduce the new time scale and investigate 18 o and accumulation anoma lies that are common to the three cores in the early holocene 7 9 11 7 ka before present three time periods with significant and synchronous anomalies in the 18 o and accumulation signals stand out the well known 8 2 ka event an event of shorter duration but of almost similar amplitude around 9 3 ka before present and the preboreal oscillation during the first centuries of the holocene for each of these sections we present a 18 o anomaly curve and a common accumulation signal that represents regional changes in the accumulation rate over the greenland ice cap

shoreline displacement and human resource utilization in the southern baltic basin coastal zone during the early holocene new insights from a submerged mesolithic landscape in south eastern sweden along parts of the hano bay coast in south eastern sweden remains of a submerged landscape can be found down to depths of almost 25 m b s l the coastal landscape was formed during two periods of

reinvestigation of the classic late glacial bolling so sequence denmark chronology macrofossils cladocera and chydorid ephippia the late glacial bolling period was first identified by johs iversen on the basis of pollen results from lake bolling so in denmark because there were no radiocarbon dates from the sequence the bolling chronozone 12 000 13 000 14c yr bp was later established on the basis of dates from other sites a new project is reinvestigating the sediments from the bolling so sequence with ams radiocarbon dating and multiproxy analyses here we present results of ams radiocarbon dating macrofossil analyses cladoceran analyses cladocera concentrations and chydorid ephippia and pediastrum analyses concentrations the ams dates on land plant remains show that the lower part of the sequence is around 12 500 14c yr bp and thus clearly pre dates the allerod chronozone however construction of a chronology for the sequence was problematic partly because of reworking of macroscopic plant remains the climate ameliorated after glacial conditions to such an extent that growth of plants could begin at ca 12 500 14c yr bp but the results of multiproxy analyses show little evidence for a further warming period during the pre allerod part of the sequence lake productivity was low and tree birch rare or maybe absent this may reflect widespread occurrence of dead ice unstable soils heavy in wash of minerogenic matter to the lake resulting in turbid water and rapid sedimentation the early pioneer vegetation was characterised by salix polaris and dryas octopetala and by herbs the allerod chronozone and especially its initial part appears to have been relatively warm but reduced cladoceran concentrations and increased proportion of chydorid ephippia suggest that climate cooled in the middle allerod and that the late allerod was colder than the early part the early younger dryas was probably colder than the late younger dryas clear warming is apparent at the beginning of the holocene where the first macrofossil evidence of trees betula pubescens populus tremula is found copyright 2004 john wiley sons ltd

the preboreal climate reversal and a subsequent solar forced climate shift accurate chronologies are essential for linking palaeoclimate archives carbon 14 wiggle match dating was used to produce an accurate chronology for part of an early holocene peat sequence from the borchert the netherlands following the younger dryas preboreal transition two climatic shifts could be inferred around 11 400 cal yr bp the expansion of birch betula forest was interrupted by a dry continental phase with dominantly open grassland vegetation coeval with the pbo preboreal oscillation as observed in the grip ice core at 11 250 cal yr bp a sudden shift to a humid climate occurred this second change appears to be contemporaneous with i a sharp increase of atmospheric c 14 ii a temporary decline of atmospheric co2 and iii an increase in the grip be 10 flux the close correspondence with excursions of cosmogenic nuclides points to a decline in solar activity which may have forced the changes in climate and vegetation at around 11 250 cal yr bp copyright c 2004 john wiley sons ltd

deglacial sea level record from tahiti corals and the timing of global meltwater discharge the timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets1 and their effects on the earth s surface2 3 moreover the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans which probably disturbed the ocean s thermohaline circulation and hence global climate4 7 sea level increases bear witness to the melting of continental ice sheets but only two such records from barbados8 9 and new guinea10 11 corals have been accurately dated but these corals overlie active subduction zones where tectonic movements are large and often discontinuous especially in new guinea so the apparent sea level records may be contaminated by a complex tectonic component here we date fossil corals from tahiti which is far from plate boundaries and thus is likely to be tectonically relatively stable and remote from the locations of large former ice sheets the resulting record indicates a large sea level jump shortly before 13 800 calendar years bp which corresponds to meltwater pulse 1a in the barbados coral records8 9 the timing of this event is more accurately constrained in the tahiti record revealing that the meltwater pulse coincides with a short and intense climate cooling event12 15 that followed the initiation of the bolling allerod warm period12 16 but preceded the younger dryas cold event by about 1 000 years

early maglemosian culture in the preboreal landscape archaeology and vegetation from the earliest mesolithic site in denmark at lundby mose sjaelland abstract the transition from late palaeolithic to early mesolithic cultures is strongly associated with the major environmental and climatic changes occurring with the shift from the younger dryas to the holocene in northern europe in this paper we present an interdisciplinary study combining archaeological and palaeoenvironmental research in an attempt to examine the relationship between environment and culture during this transition lundby mose is a former kettle hole lake in southern denmark where the earliest danish human traces of the holocene were excavated two types of bone deposits were found 1 ritual offerings of worked marrow split elk bones and antler and 2 settlement waste with multiple species these date to the early holocene and are affiliated to the early maglemose culture the modelled 14 c ages suggest that the bones were deposited in four phases a pollen based palaeoenvironmental reconstruction suggests that the ritual offerings were deposited in an environment of limited underdeveloped forest with unstable soils and areas of open grassland the settlement waste deposit is associated with a more developed preboreal forest type this forest type was not fully established until c 11 250 cal bp and if substantiated by further evidence may be one of the reasons why there are no known early maglemose preboreal settlement sites in southern scandinavia

a further note on earthquake size distributions abstract at the scale range of 1 to 10 km faults are not continuous surfaces but are tabular bodies composed of a mesh of subparallel unconnected strands or subfaults the cumulative length distribution of these subfaults is observed to be a power law with an approximate exponent of 2 and an upper fractal limit at w the seismogenic width if it is assumed that small earthquakes with lengths l w represent the rupture of these subfaults this offers a physical explanation for small earthquakes having their observed power law distribution with exponent 2 3 this further implies that any earthquake will be composed of a population of subevents involving the rupture of this population of subfaults precisely what was proposed by frankel 1991 to explain the 2 high frequency falloff of earthquake displacement spectra

the 8k event cause and consequences of a major holocene abrupt climate change abstract a prominent abrupt climate event about 8200 years ago brought generally cold and dry conditions to broad northern hemisphere regions especially in wintertime in response to a very large outburst flood that freshened the north atlantic changes were much larger than typical climate variability before and after the event with anomalies up to many degrees contributing to major displacement of vegetative patterns this 8k event provides a clear case of cause and effect in the paleoclimatic realm and so offers an excellent opportunity for model testing the response to north atlantic freshening has the same general anomaly pattern as observed for older events associated with abrupt climate changes following north atlantic freshening and so greatly strengthens the case that those older events also reflect north atlantic changes the north atlantic involvement in the 8k event helps in estimating limits on climate anomalies that might result in the future if warming caused ice melt and hydrologic cycle intensification at high latitudes lead to major changes in north atlantic circulation few model experiments have directly addressed the 8k event and most studies of proxy records across this event lack the time resolution to fully characterize the anomalies so much work remains to be done

freshwater outbursts to the oceans from glacial lake agassiz and their role in climate change during the last deglaciation abstract lake agassiz was the largest lake in north america during the last deglaciation as the laurentide ice sheet lis retreated large volumes of water stored in this proglacial lake were episodically released into the oceans these waters were variably routed to the gulf of mexico arctic ocean north atlantic ocean and hudson bay during this period the three largest cooling events in the northern hemisphere closely followed 4 of the 5 largest outbursts from lake agassiz 1 the younger dryas which was preceded by a release of 9500 km 3 2 the preboreal oscillation preceded by releases of 9300 km 3 and 5900 km 3 and 3 the 8 2 ka cold event preceded by a 163 000 km 3 outburst these are respectively fluxes of 0 30 sv 0 29 sv 0 19 sv and 5 2 sv if released in 1 year because the influx of freshwater reaching the north atlantic ocean can inhibit thermohaline circulation partly depending on whether the ocean was in a glacial interglacial or transitional mode of circulation we believe that at least these large outbursts from lake agassiz may have provided the triggers for changes in ocean circulation and in turn for widespread climate change

dating the trollesgave site and the bromme culture chronological fix points for the lateglacial settlement of southern scandinavia abstract the bromme culture belongs to the lateglacial the period when people settled in the recently deglaciated southern scandinavia until now there have been only a few imprecise fix points relating to the chronological position of this archaeological culture this situation can now be improved with the aid of research results from a bromme culture settlement at trollesgave in se denmark using pollen and plant macrofossil data lateglacial lacustrine deposits containing waste material from the settlement can be assigned to the end of the climatically mild allerod period a series of 14 c dates establishes the age of the settlement as c 10 826 49 14 c years bp 12 871 12 590 cal yr bp by correlation with climate data from the greenland ice cores the occupation can be assigned to the early part of the cold climatic zone gs 1 thus demonstrating that the global ice core climate zones are not absolutely synchronous with the regional division into biozones

the preboreal oscillation around the nordic seas terrestrial and lacustrine responses the occurrence of an early preboreal climatic cooling oscillation pbo in lacustrine and glacial records from northwest europe iceland and greenland is reviewed and documented the often subtle response of the proxy records to this oscillation in combination with its short duration make it difficult to detect owing to its chronostratigraphic position between the 10 000 9900 and 9600 9500 14 c plateaux c 11 300 11 150 calendar yr bp it is also difficult to 14 c date with precision we find that the vegetation response to the pbo varies between sites and regions in contrast to the pioneer vegetation in iceland and southern sweden the expanding birch pine forest in germany denmark was more susceptible to deteriorating growing conditions the combined lacustrine tree ring and glacial records imply that the pbo was characterised by cool and humid conditions throughout northwestern and central europe this is documented by vegetation changes decreased aquatic production increased soil erosion increased 2 h and 13 c content in tree rings readvances or stillstands of the ice sheet in norway and finland and ingression of brackish water into the baltic icelandic proxy records from lake sediments and glacial moraines imply cooler conditions than during the previous preboreal period but not as extreme as during the younger dryas greenland records suggest that the early preboreal was characterised by ice readvances as an effect of cool climate and increased precipitation in relation to the younger dryas it was not until the end of the pbo that climate was warm enough to melt the land based ice sheet this preboreal oscillation found on both sides of the nordic seas is interpreted as an effect of increased freshwater forcing on the thermohaline circulation in the nordic seas which is implied by a simultaneous and distinct rise in the atmospheric 14 c 12 c ratio a slow down of the thermohaline circulation may tempor arily have pushed the polar front further south 1997 by john wiley sons ltd preboreal oscillation thermohaline circulation lacustrine records glacial records chronology

a new greenland ice core chronology for the last glacial termination 1 we present a new common stratigraphic timescale for the north greenland ice core project ngrip and grip ice cores the timescale covers the period 7 9 14 8 kyr before present and includes the bolling allerod younger dryas and early holocene periods we use a combination of new and previously published data the most prominent being new high resolution continuous flow analysis cfa impurity records from the ngrip ice core several investigators have identified and counted annual layers using a multiparameter approach and the maximum counting error is estimated to be up to 2 in the holocene part and about 3 for the older parts these counting error estimates reflect the number of annual layers that were hard to interpret but not a possible bias in the set of rules used for annual layer identification as the grip and ngrip ice cores are not optimal for annual layer counting in the middle and late holocene the timescale is tied to a prominent volcanic event inside the 8 2 kyr cold event recently dated in the dye 3 ice core to 8236 years before a d 2000 b2k with a maximum counting error of 47 years the new timescale dates the younger dryas preboreal transition to 11 703 b2k which is 100 150 years older than according to the present grip and ngrip timescales the age of the transition matches the gisp2 timescale within a few years but viewed over the entire 7 9 14 8 kyr section there are significant differences between the new timescale and the gisp2 timescale the transition from the glacial into the bolling interstadial is dated to 14 692 b2k the presented timescale is a part of a new greenland ice core chronology common to the dye 3 grip and ngrip ice cores named the greenland ice core chronology 2005 gicc05 the annual layer thicknesses are observed to be log normally distributed with good approximation and compared to the early holocene the mean accumulation rates in the younger dryas and bolling periods are found to be 47 2 and 88 2 respectively

barotropic wave propagation and instability and atmospheric teleconnection patterns abstract a global barotropic model linearized about the 300 mb climatological mean january flow is perturbed by applying a series of localized forcings distributed throughout the tropics and subtropics structures which resemble the observed pacific north american and east atlantic teleconnection patterns noted by wallace and gutzler 1981 tend to recur in the responses similar patterns are found to result from the dispersion of isolated initial perturbations placed at a variety of locations in the tropics and midlatitudes it is shown that these structures are related to the most rapidly growing mode associated with barotropic instability of the zonally varying climatological basic state in the absence of damping this mode has an e folding time of about a week and a period close to 50 days in localized regions the instantaneous growth rates can be competitive with those of baroclinic instability these episodes of rapid local barotropic growth are interspersed with intervals in which the local

the early mesolithic haverbeck site northwest germany evidence for preboreal settlement in the western and central european plain abstract archaeological sites dating from the preboreal are of special interest since they mark the turning point in the transition between the cultures of the late pleistocene and the holocene in spite of their relevance only few sites in the western and central european plain have become known thus providing an inhomogeneous basis for further hypotheses in particular sites in the widespread aeolian landscapes have been neglected for a long time due to their uncertain genesis dating problems and obviously insufficient preservation our investigations of the haverbeck site situated in sandy aeolian substrate seek to enhance knowledge about the preboreal mesolithic the well preserved archaeological spatial technological and functional patterns and the geoarchaeological site formation were studied sedimentological and palaeopedological analyses supported by 14 c and osl dating results revealed that artefacts were deposited during the preboreal on sands which had accumulated during the younger dryas and were reactivated in subsequent periods atlantic subboreal subatlantic in spite of these processes the artefacts remained unimpaired in their relative horizontal positions enabling spatial analyses which show a zonal differentiation and a prevalence of retooling and replacing activities these results offer an insight into spatial and functional differentiations of the local early mesolithic subsistence evidently including particular places for gathering and processing raw material a comparison between the microlithic spectrum left behind and the number of points produced as concluded from the microburins indicates a greater typological differentiation than previously assumed for the early mesolithic the remarkable variability of scraper forms obviously intentionally abandoned in a high number and replaced by new tools emphasizes the strong influence of functional elements on the typological assemblage composition it is suggested that early mesolithic assemblages could display rather functional requirements or tasks performed than significant chronological or regional influences in addition the combination of 14 c osl and pedology helped to reconstruct the aeolian accumulation erosion dynamics and to present a considerable sequence of processes some of which are closely connected with human activities

late weichselian environmental change in southern sweden and denmark a synthesis is presented of the envronmental and climatic variations that are inferred to have occurred in southern sweden up to latitude 59 n and denmark during the weichselian late glacial 14 9 ka bp the chronology and characteristics of the main phases of deglaciation sea level change periglacial activity soil development vegetation cover and climate change are summarised a curve representing the main changes in temperature including quantitative estimates based upon beetle data and using the mutual climatic range method is presented

preboreal climate oscillations in europe wiggle match dating and synthesis of dutch high resolution multi proxy records abstract in order to compare environmental and inferred climatic change during the preboreal in the netherlands five terrestrial records were analysed detailed multi proxy analyses including microfossils e g pollen spores algae and fungal spores macroremains e g seeds fruits wood mosses etc and loss on ignition measurements were carried out with high temporal resolution to link the five preboreal records accurate chronologies were produced by ams 14c wiggle match dating the dutch records show that following the lateglacial holocene climate warming birch woodlands expanded between 11 530 and 11 500 cal bp during the friesland phase of the preboreal after the friesland phase two distinct climatic shifts could be inferred 1 around 11 430 11 350 cal bp the expansion of birch forests was interrupted by a dry continental phase with open grassland vegetation the rammelbeek phase this phase was coeval with the coldest part of the preboreal oscillation pbo as observed in the 18o record of the greenland ice core records and has been attributed to a large meltwater flux that resulted in a temporary decrease of the thermohaline circulation in the north atlantic 2 at the start of the late preboreal between 11 270 and 11 210 cal bp a sudden shift to a more humid climate occurred and birch forests expanded again a simultaneous increase in the cosmogenic nuclides 14c and 10be suggests that these changes in climate and vegetation were forced by a sudden decline in solar activity expansion of pine occurred during the later part of the late preboreal at the onset of the boreal between 10 770 and 10 700 cal bp dense woodlands with hazel oak elm and pine started to develop in the netherlands

role of transients in the dynamics of east asian summer seasonal mean circulation anomalies a study of 1993 and 1994 abstract by using the national centers for environmental prediction reanalysis data and a nonlinear barotropic model the transient activities and the possible role of transient vorticity fluxes in the maintenance of east asian summer seasonal mean circulation anomalies associated with japan s extremely cool and wet summer of 1993 and hot and dry summer of 1994 are examined data analysis shows that the summertime atmospheric circulation and the transient activity anomalies exhibit nearly opposite patterns over east asia during these two years vorticity budget calculations indicate that the anomalies of transient activities in these two years produced strong transient vorticity flux forcing anomalies that are comparable in magnitude to the divergent forcing anomalies over east asia the nonlinear barotropic model when forced by the anomalous divergence and transient vorticity flux forcing together produces simulations that bear resemblance to the observed summertime seasonal mean circulation anomalies

a complete terrestrial radiocarbon record for 11 2 to 52 8 kyr b p radiocarbon 14c provides a way to date material that contains carbon with an age up to 50 000 years and is also an important tracer of the global carbon cycle however the lack of a comprehensive record reflecting atmospheric 14c prior to 12 5 thousand years before the present kyr b p has limited the application of radiocarbon dating of samples from the last glacial period here we report 14c results from lake suigetsu japan 35 35 n 135 53 e which provide a comprehensive record of terrestrial radiocarbon to the present limit of the 14c method the time scale we present in this work allows direct comparison of lake suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels

possible causes of anomalies in seasonal mean circulation patterns during the 1982 83 el nino event abstract for six consecutive seasons around the 1982 83 el nino event the relation between observed anomalies in atmospheric circulation patterns and anomalies in various forcing mechanisms is diagnosed a linear model is used in an attempt to simulate atmospheric anomalies as a stationary response to observed anomalies in tropical diabatic heating mountain and transient eddy effects the response to forcing by transient eddies is large for all seasons and is significantly correlated with observed anomalies to what extent observed anomalous transient eddy activity is related to anomalous conditions at the earth s surface can not be deduced from these experiments the midlatitude effect of tropical heating are found to be small oven during the mature phase of the 1982 83 warming event however these results are critically dependent on the exact location of the zero wind line the effect of the orography caused by observed anomalies in zonal mean westerly winds is small in general in one season when el

variability and seasonality of north atlantic climate during the early holocene evidence from faroe island lake sediments based on their position in relation to major ocean currents palaeoclimatic archives in the faroe islands are expected to be sensitive recorders of variations in north atlantic circulation the multiproxy analysis magnetic susceptibility total carbon nitrogen and sulphur biogenic silica grains 255 mu m of a lacustrine record with both winter and summer climate indicators illustrates the variability of faroese climate during the early holocene c 11 300 10 240 cal yr bp and allows comparison with other records in the region our high resolution record suggests a period of predominantly winter cooling and increased storminess centred at c 11 150 cal yr bp followed by a period of stability between c 11 000 and 10 680 cal yr bp which correlates with a time when the north atlantic was particularly free of meltwater incursions after c 10 680 cal yr bp both winter and summer indicators show an increase in variability broadly synchronous with increased variability at other north atlantic sites within this time period a predominantly winter cooling centred at c 10 600 cal yr bp a winter summer cooling centred at c 10 450 cal yr bp and a winter summer cooling centred at c 10 300 cal yr bp are recorded these distinctive coolings correspond to periods of ice core delta o 18 inferred lowered atmospheric temperatures over greenland and the reoccurrence of meltwater outbursts at c 10 600 10 500 and 10 350 cal yr bp less

exploring human responses to climatic fluctuations and environmental diversity two stories from mesolithic norway abstract this paper explores environmental variations in time and space adaptive strategies and possible cultural responses to climatic changes as manifested through archaeological data in terms of lithic tool technology site density and settlement patterns the objective is investigated by two case studies from mesolithic norway the first case deals with the earliest settlement phase of norway c 11 500 10 000 cal bp which climatically encompasses gradual changes from cold arctic conditions to a milder sub arctic climate as well as the rapid preboreal oscillation pbo cold event the second case explores the 8200 cal bp cold event and its effect on culture and settlement in southeast norway the studies suggest that the coastal settlement in terms of site density was not affected by either the pbo or the 8200 cal bp event changes in site location patterns seem to have occurred gradually and on a long term scale shifts in lithic technology are detected within the mesolithic periods but a correlation between abrupt climatic alterations and cultural changes are yet to be proved we argue therefore that in these northern coastal environments declining temperatures may have had less impact than on the continental plains and may in fact have improved the living conditions for a range of marine species also the mesolithic populations seemed to have employed a generalized lithic toolkit and a flexible mobility system adaptive strategies that was able to withstand environmental variations in time and space

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research