holocene palaeoclimates from peat stratigraphy macrofossil proxy climate records from three oceanic raised bogs in england and ireland quantified analyses of plant macrofossil remains have been made from three profiles of peat from raised bogs spanning a distance of 425 km from western ireland to northern england the reconstructed vegetation of each profile is related to changing bog surface wetness bsw and since the bogs are ombrotrophic these bsw changes are interpreted in terms of changing climate using age depth models based on a total of 49 radiocarbon dates a number of wetter and drier phases are identified and phase shifts to wetter and or cooler climates are defined prominent coincident changes to wetter conditions are dated in at least two of the profiles to ca 4400 4000 1750 1400 and 1000 cal bp and in all three profiles at 3200 2750 2350 2250 and around 700 cal bp these phases are related to proxy climate changes in other terrestrial data sets from northwest europe and a broad degree of synchroneity is demonstrated

testing the timing of radiocarbon dated events between proxy archives for interpreting past changes on a regional or global scale the timings of proxy inferred events are usually aligned with data from other locations however too often chronological uncertainties are ignored in proxy diagrams and multisite comparisons making it possible for researchers to fall into the trap of sucking separate events into one illusionary event or vice versa here we largely solve this suck in and smear syndrome for radiocarbon 14 c dated sequences in a bayesian framework millions of plausible age models are constructed to quantify the chronological uncertainties within and between proxy archives we test the technique on replicated high resolution 14 c dated peat cores deposited during the little ice age c ad 14001900 a period characterized by abrupt climate changes and severe 14 c calibration problems owing to internal variability in proxy data and uncertainties in age models these and possibly many more archives are not consistent in recording decadal climate change through explicit statistical tests of palaeoenvironmental hypotheses we can move forward to systematic interpretations of proxy data however chronological uncertainties of non annually resolved palaeoclimate records are too large for answering decadal timescale questions

holocene carbon accumulation rates from three ombrotrophic peatlands in boreal quebec canada impact of climate driven ecohydrological change understanding the processes controlling peatland carbon c sequestration is critical to anticipate potential changes in the global c cycle in response to climate change although identification of these factors may be relatively straightforward on seasonal timescales at centennial to millennial timescales complexities arise because of interactions between climate vegetation hydrology and long term ecological processes to better understand the factors controlling long term c accumulation holocene rates of c sequestration were quantified from three pristine ombrotrophic peatlands in boreal quebec northeastern canada 52 n 75 76 w bulk density and loss on ignition analyses combined with radiocarbon dating and age depth modelling were used to estimate long term apparent rates of carbon accumulation past changes in vegetation and water table depth were obtained from plant macrofossil and testate amoeba analysis earliest regional peat accumulation started 7520 cal bp with long term rates of c s

biomarkers as proxies for plant inputs to peats an example from a sub boreal ombrotrophic bog lipid distributions in modern peat forming plants were determined and compared to biomarkers recovered from a ca 2800 year old peat deposited in a dutch ombrotrophic bog the peat section spans a well constrained shift in local hydrology and vegetation and potential molecular proxies for plant inputs were directly tested against the macrofossil record based on the analyses of modern plants low molecular weight lmw n alkanes c23 c25 and high molecular weight n alkanes c33 are proposed as potential biomarkers for sphagnum and non sphagnum inputs respectively consistent with this in the bargerveen peat core lmw n alkane abundances increase and hmw n alkane abundances decrease coincident with the shift to sphagnum dominated peat additional potential proxies include the abundances of c22 alkanedioic acid and phytenyl phytenoate as sphagnum indicators and the abundances of the triterpenoids taraxer 14 ene and taraxast 20 ene as biomarkers for ericaceae rootlets

development and refinement of proxy climate indicators from peats peat especially from acidic mires bogs is a natural archive of past environmental change reconstructions of past climate from bogs commenced in the 19th century through examination of visible peat stratigraphy and later formed the basis for a postglacial climatic scheme widely used in northwest europe nevertheless misconceptions as to how bogs grow led to a 50 year lacuna in peat climate study before the concept of cyclic regeneration in bogs was refuted in recent decades research using proxy climate indicators from bogs has burgeoned a range of proxies for past hydrological change has been developed as well as use of pollen bog oaks and pines and other data to reconstruct past temperatures most of this proxy climate research has been carried out in northern europe but peat based research in parts of asia and north america has increased particularly during the last decade while research has also been conducted in australia new zealand and south america this paper reviews developments in proxy climate reconstructions from peatlands chronicles use of a range of palaeo proxies such as visible peat stratigraphy plant macrofossils peat humification testate amoebae and non pollen palynomorphs and explains the use of wiggle match radiocarbon dating and relationship to climate shifts it details other techniques being used increasingly such as biomarkers stable isotopes inorganic geochemistry and estimation of dust flux and points to new proxies under development although explicit protocols have been developed recently for research on ombrotrophic mires it must be recognised that not all proxies and techniques have universal applicability owing to differences in species assemblages mire formation topographic controls and geochemical characteristics

aeolian sediment reconstructions from the scottish outer hebrides late holocene storminess and the role of the north atlantic oscillation northern europe can be strongly influenced by winter storms driven by the north atlantic oscillation nao with a positive nao index associated with greater storminess in northern europe however palaeoclimate reconstructions have suggested that the nao storminess relationship observed during the instrumental period is not consistent with the relationship over the last millennium especially during the little ice age lia when it has been suggested that enhanced storminess occurred during a phase of persistent negative nao to assess this relationship over a longer time period a storminess reconstruction from an nao sensitive area the outer hebrides is compared with late holocene nao reconstructions the patterns of storminess are inferred from aeolian sand deposits within two ombrotrophic peat bogs with multiple cores and two locations used to distinguish the storminess signal from intra site variability and local factors the results suggest storminess increased after 1000 cal yrs bp with higher storminess during the medieval climate anomaly mca than the lia supporting the hypothesis that the nao storminess relationship was consistent with the instrumental period however the shift from a predominantly negative to positive nao at c 2000 cal yrs bp preceded the increased storminess by 1000 years we suggest that the long term trends in storminess were caused by insolation changes while oceanic forcing may have influenced millennial variability

multiproxy evidence of little ice age palaeoenvironmental changes in a peat bog from northern poland little ice age lia climatic deteriorations have been abundantly documented in various archives such as ice lake sediments and peat bog deposits palaeoecological analyses of peat samples have identified these climatic deteriorations using a range of techniques for example palynology plant macrofossils testate amoebae or carbon isotopic analyses the use of inorganic geochemistry and the reconstruction of dust fluxes has remained a challenge in tracing the nature of lia climatic changes although the idea of enhanced erosion conditions and storminess is commonly discussed the conditions for dust deposition in peatlands over europe during the lia are rarely favourable because the natural forest cover over europe was much more important than nowadays preventing dust deposition this intense forest canopy masks the deposition of dust in peatlands in northern poland near the baltic shore the slowin skie blota area was deforested around ad 1100 ie just before the lia and therefore constitutes a key area for the reconstruction of lia climatic change with the support of a well constrained chronology climatic fluctuations are recorded in an ombrotrophic bog using inorganic geochemistry plant macrofossils and carbon isotopic analyses the reconstruction of lia climatic changes is in good agreement with other records from poland and ne europe however a c 50 year discrepancy can be observed between various records this discrepancy is possibly due to progressive time dependent cooling gradient from north to south europe

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

study of the h v spectral ratio method for determining average shear wave velocities in the mississippi embayment abstract the shear wave velocity v s structure of the deep sediments in the mississippi embayment is of interest to engineers and seismologists due to its influence on seismic wave propagation and site response during an earthquake although the shallow v s structure top 30 to 60 m is generally well characterized information on the v s structure at greater depths to 1000 m in some regions is very limited past studies have developed relationships between the average v s v s ave of post paleozoic sediments in the embayment as a function of sediment thickness one of these studies used converted body wave arrivals while the other used ambient noise measurements processed with the horizontal to vertical spectral ratio hvsr method interestingly these two approaches yielded relationships that differed by about 25 to 30 the objective of this study is to investigate the cause of the discrepancy between these relationships and identify the more reliable relationship for the v s structure in the mississippi embayment experimental measurements of ambient noise were performed at eleven deep soil sites in the mississippi embayment and analyzed using the hvsr method the results from the experimental study yielded v s ave values that were consistent with findings from the previous hvsr study however simulations of body and surface wave propagation performed using estimated full depth v s profiles at each site showed that the methodology used to develop the velocity thickness relationship specifically the approximate relationship used to relate site frequency sediment thickness and v s produces an overestimation of the true v s ave for the profile by 25 to 30

solar and proxy sensitivity imprints on paleohydrological records for the last millennium in west central europe this paper presents a lake level record established for the last millennium at lake saint point in the french jura mountains a comparison of this lake level record with a solar irradiance record supports the hypothesis of a solar forcing of variations in the hydrological cycle linked to climatic oscillations over the last millennium in west central europe with higher lake levels during the solar minimums of oort around ad 1060 wolf around ad 1320 sporer around ad 1450 maunder around ad 1690 and dalton around ad 1820 further comparisons of the saint point record with the fluctuations of the great aletsch glacier swiss alps and a record of rhone river floods from lake bourget french alps give evidence of possible imprints of proxy sensitivity on reconstructed paleohydrological records in particular the great aletsch record shows an increasing glacier mass from ad 1350 to 1850 suggesting a cumulative effect of the little ice age cooling and or a possible reflection of a millennial scale general cooling until the mid 19th century in the northern hemisphere in contrast the saint point and bourget records show a general trend toward a decrease in lake levels and in flood magnitude anti correlated with generally increasing solar irradiance

rich fen development in ce europe resilience to climate change and human impact over the last ca 3500 years here for the first time in se poland we document the long term development of a rich fen and assess its sensitivity to climate change and human impacts over the last ca 3500 years our results are based on a high resolution continuous plant macrofossil remains mollusc and pollen record complemented by geochemical mineral magnetic and physical characterisation and radiocarbon dating from bagno serebryskie rich fen located in se poland based on the palaeoecological data we distinguished five stages of wet habitat conditions 5000 3300 2800 2150 1600 1100 750 230 150 10 cal yr bp and five dry periods at ca 3300 2800 2150 1600 1100 750 230 150 10 to 64 cal yr bp the pollen and geochemistry records particularly pb show that the first human activity in the study area occurred ca 3200 cal yr bp and increased markedly from 500 cal yr bp affecting local plant development including the population size of cladium mariscus our study has shown that despite human impact drainage fire bagno serebryskie peatland has hosted rare presently protected species such as cladium mariscus for hundreds of years we conclude that in common with ombrotrophic bogs rich fen ecosystems can provide a reliable source of palaeoclimatic and palaeohydrological data our study also shows that a large peatland 376 ha can be as sensitive a palaeohydrological archive as smaller mires

a quantitative holocene climatic record from diatoms in northern fennoscandia abstract a diatom based calibration model for predicting summer temperatures was developed using climatically sensitive subarctic lakes in northern fennoscandia the model was applied to a sediment core from a treeline lake to infer trends in holocene climate the record exhibits long term variations as well as a series of shorter term fluctuations on a time scale of centuries summers were warmest in the area about 6200 cal yr b p and featured distinct cooling episodes around 8300 7200 4200 3000 and 400 cal yr b p most of these coinciding with some known climate events e g the 8200 cal yr b p event and the little ice age the similarity of the observed shifts with the pacings of climate events from marine and ice core records represents evidence for coupled ocean atmosphere forcing of the regional climate

the use of principle component analyses in characterising trace and major elemental distribution in a 55 kyr peat deposit in tropical australia implications to paleoclimate abstract the lynch s crater peat deposit in ne australia is a sensitive environmental archive located in the tropical southern hemisphere this unique deposit illustrates that local and regional changes had a profound effect on the local australian ecosystem over the past 55 kyr to obtain a proxy of past climate changes trace and major element geochemistry analyses were applied to a 13 m peat core from the crater principle component analysis pca was used to identify the main factors that control elemental distribution in the peat and to add interpretative strength to the geochemical behavior of selected major and trace elements for example sc al cu and pb were found to be related to increased erosion of the basin soils and from this several periods of significant flux from atmospheric input and or terrigenous run off were identified geochemically mobile elements during rock weathering and pedogenesis such as mg ca and sr helped to identify the peat ombrotrophic minerotrophic boundary at 1 5 m depth and offered important information about fluxes of these nutrients to the mire and their dynamics within the deposit arsenic and v comparisons between the peat record high concentrations in some peat sections and in local basin rocks very low concentrations suggested the presence of a long range atmospheric dust source early in the formation of the mire the lynch s crater peat record presents a continuous record of environmental change in tropical australia and contributes new understanding to geochemical processes in peatlands

benthic foraminifera as indicators of relative sea level fluctuations paleoenvironmental and paleoclimatic reconstruction of a holocene marine succession calabria south eastern tyrrhenian sea abstract this study presents the results of an integrated stratigraphic analysis conducted on a marine gravity core msk 12 c4 recovered from the outer continental shelf 82 m water depth of western calabria 2 6 km ne of capo vaticano eastern tyrrhenian margin the gravity core msk 12 c4 recovered a stratigraphic succession of 4 18 m beneath the seafloor representing the last 11 1 ka sedimentological analysis micropaleontological quantitative analysis on benthic foraminiferal assemblages tephrostratigraphy sequence stratigraphic analysis of high resolution reflection seismic data recorded in the core site area and ams 14 c absolute age determinations allowed reconstructing the marine record of the eastern tyrrhenian margin major results of the research work include the progressive sea level rise that controlled the evolution of the western shelf of calabria during the holocene and the identification of significant paleoenvironmental and paleoclimatic events first a short lived period 10 6 9 4 ka bp characterized by a significant increase river discharge seems to reflect a major rainfall during the earliest onset of the holocene climatic warming second the occurrence of a stratigraphic gap from 8 4 to 5 ka bp possibly the result of non deposition and or erosion due to bottom currents the latter should follow from a major reorganization of the deep water currents system that accompanied the climax of the holocene warming holocene climatic optimum third the micropaleontological evidence of the little ice age lia that on the basis of the chronology adopted in this study can be constrained between 1600 ad and 1850 ad

centennial scale climate change in ireland during the holocene we examine mid to late holocene centennial scale climate variability in ireland using proxy data from peatlands lakes and a speleothem a high degree of between record variability is apparent in the proxy data and significant chronological uncertainties are present however tephra layers provide a robust tool for correlation and improve the chronological precision of the records although we can find no statistically significant coherence in the dataset as a whole a selection of high quality peatland water table reconstructions co vary more than would be expected by chance alone a locally weighted regression model with bootstrapping can be used to construct a best estimate palaeoclimatic reconstruction from these datasets visual comparison and cross wavelet analysis of peatland water table compilations from ireland and northern britain show that there are some periods of coherence between these records some terrestrial palaeoclimatic changes in ireland appear to coincide with changes in the north atlantic thermohaline circulation and solar activity however these relationships are inconsistent and may be obscured by chronological uncertainties we conclude by suggesting an agenda for future holocene climate research in ireland

mire development pathways and palaeoclimatic records from a full holocene peat archive at walton moss cumbria england plant macrofossil data have been used to identify the successive mire communities occupying both central and marginal locations in the walton moss peatland complex during the last 10 500 years the reconstructed pathways of mire development indicate that early holocene fen and fen carr communities were succeeded by species indicative of deep mire water tables and oligotrophic conditions the character of the fen bog transition fbt is compared with similar records of peatland development from britain and scandinavia and with independent climate data for the early holocene the pseudohochmoor of central europe is suggested as an approximate modern analogue for the dry pioneer oligotrophic mire type and alternative explanations for its presence are explored the first major increase in ombrotrophic sphagna occurred at c 7800 cal bp overlying sphagnum peats provide a continuous record of climate change inferred from fluctuations in raised mire surface wetness the proxy palaeoclimate record reconstr

the ocean circulation in the southern hemisphere and its climatic impacts in the eocene abstract opening of southern ocean gateways may have had a controlling influence on the evolution of global climate the largest step in the history of cenozoic climate from an eocene greenhouse toward the modern glaciated state is correlated with opening of a deep water connection between the southern indian and southern pacific oceans this study synthesizes results from previous work assesses the possibility that ocean heat transport was much greater than modern during the globally warm eocene and explores the sensitivity of polar climate to large changes in ocean heat transport the magnitudes of these sensitivities are compared with those due to greenhouse gas concentration changes we find that ocean heat transport was unlikely to have been sufficiently greater than modern during the eocene to explain the change in the climate specifically in order to have significantly affected antarctic climate ocean heat transport changes would have had to change by an order of magnitude much greater than the largest change produced in our simulations in coupled climate model simulations changes in co2 concentrations from 1120 to 560 ppm supported by proxy records lead to significant antarctic responses in the absence of ocean heat transport changes the results show that antarctic snow accumulation is primarily controlled by changes in summer temperature not precipitation and that snow did not remain on antarctica during summer months in eocene even at low greenhouse gas concentrations greenhouse gas concentration changes and subsequent processes such as ice albedo and weathering feedbacks were more likely to have been the primary cause of antarctic glaciation than ocean heat transport changes

dating raised bogs new aspects of ams 14c wiggle matching a reservoir effect and climatic change abstract high resolution ams dating of holocene raised bog deposits engbertsdijksvenen the netherlands shows natural 14c variations wiggles which can be matched with the dendrochronological calibration curve comparison of our results with other conventionally dated peat cores and the 14c record shows an unexpected and as yet unreported reservoir effect and a marked and sudden wetting of the bog surfaces coinciding with the advent of a sporer type solar minimum the homeric minimum the potential of ams dating to vastly improve the accuracy of holocene chronologies is demonstrated

evidence from northwest european bogs shows little ice age climatic changes driven by variations in solar activity fluctuations in holocene atmospheric radiocarbon concentrations have been shown to be due to variations in solar activity analyses of both 10 be and 14 c nuclides cone rm that production ratechanges during

rapid development and infilling of a buried gully under cropland central belgium abstract analysis of contemporary and past gully erosion and infilling processes allowed to reconstruct the long term evolution of a permanent gully system under cropland an active and a buried gully under cropland were investigated the recent sediment deposits within the active gully adjacent to the buried gully showed that the recent gully was filling in at a mean rate of 6 4 cm a 1 in the buried gully several erosion and deposition phases could be identified and the type of deposited sediments revealed a complex infilling history charcoal pottery and brick fragments of different sizes were found at all depths of the gully infilling their age indicates that the first gully incised after the midst of the 17th century most probably in the second half of the 18th century or the early 19th century gully morphology and analogy with the processes in the recent gully indicate that the buried gully filled in rapidly overall five cycles of cut and fill occurred in 350 years or less and four cycles even within little less than a few decades indicating that gully development and infilling under cropland can be very rapid processes

changes in solar activity and holocene climatic shifts derived from 14c wiggle match dated peat deposits closely spaced sequences of accelerator mass spectrometer ams 14 c dates of peat deposits display century scale wiggles which can be e tted to the radiocarbon calibration curve by wiggle matching such sequences high precision calendar age chronologiescan be generated which show that changes in mire surface wetness during the bronze age iron age transition c 850 cal bc and the little ice age wolf sporer maunder and dalton minima occurred during periods of suddenly increasing atmospheric concentration of 14 c replicate evidence from peat based proxy climate indicators in northwest europe suggest these changes in climate may have been driven by temporary declines of solar activity carbon accumulation rates of two raised peat bogs in the uk and denmark record low values during the little ice age which ree ects reduced primary productivity of the peat forming vegetation during these periods of climatic deterioration

interrelated continental sedimentary environments in the central iberian range spain facies characterization and main palaeoenvironmental changes during the holocene a complex holocene system in the central iberian range ne spain has been reconstructed on the basis of sediments recovered from cores and in situ observations small alluvial fans graded into a wide shallow lacustrine area anavieja lake that connected downstream with a carbonate fluvial system with associated vegetated zones the fluvial system was mainly characterized by the development of tufa barriers especially during the first part of the holocene that separated pools or small lakes oncolites detrital tufas calcarenites and marls were deposited in these pools adjacent vegetated areas were covered by macrophytes and were episodically reached by detrital tufa supplies indicating high flood stages high sedimentary rates existed in both the fluvial including the pools and vegetated areas suggesting that despite the common erosion of tufas a clear aggradating evolution existed by contrast very low sedimentary rates were registered in the anavieja lake all the environments but especially the vegetated areas registered the climate evolution during the holocene although the onset of the holocene was characterized by wide climate variability warm and humid conditions dominated during the first part and drier conditions during the second part a water level recovery seems to have been existed during the last millennium this is a good example of the potential of continental systems other than lakes to be useful for palaeoenvironmental and palaeoclimatic studies

a sensitive high resolution record of late holocene climatic change from a raised bog in northern england proxy climatic data in the form of plant macrofossils have been analysed from a 5 m core from bolton fell moss cumbria uk detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years the record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog surface wetness for the latter half of the holocene as bog surface wetness is directly controlled by the prevailing climatic conditions this reconstruction can be viewed as a proxy climate record twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12 4 yr cm 1 the regular sampling intervals thus provide a time series of past bog surface wetness spectral analyses of this series indicates that wetness changes are cyclic with a ca 800 year periodicity

replicability and variability of the recent macrofossil and proxy climate record from raised bogs field stratigraphy and macrofossil data from bolton fell moss and walton moss cumbria england replication of results is a basic tenet of science but in palaeoecology this is very time consuming and the signal is subject to noise the derivation of proxy climate signals from ombrotrophic peat was carried out originally using samples from open peat faces where the stratigraphic relationships could be easily observed now that such sections are rare and often degraded there is a need to demonstrate that data can be replicated from core profiles ten short cores taken from two adjacent bogs have been analysed for macrofossils and show a coherent series of changes which are also similar to previous profiles from the same sites it is concluded that variation between profiles is slight and less than observations of present vegetation mosaics might suggest recommendations for a standard approach to fieldwork on raised bogs that emphasises the utility of subfossil pool layers are proposed and the need for a secure chronology is stressed 1998 john wiley sons ltd

14c ams wiggle matching of raised bog deposits and models of peat accumulation abstract high resolution accelerator mass spectrometer ams 14 c dates of selected plant macrofossils from the raised bog engbertsdijksvenen eastern netherlands show century scale wiggles analogous to the radiocarbon calibration curve we used three relative time scales viz based on depth mass and pollen concentration respectively to match the peat ams dates to the calibration curve this procedure is repeated for one conventionally dated core for each relative time scale realistic confidence intervals are calculated depth appears to be the best time scale for certain stratigraphical units of a core this justifies using depth for wiggle matching conventionally dated mire cores published by others even when 14 c errors are larger our evidence shows four major sources of 14 c variation for mire deposits compared to treerings 1 dating error due to sample composition this includes a reservoir effect demonstrated for many bulk peat samples 2 hiatuses causing a sudden leap of peat 14 c age 3 changing accumulation rates apparent from a break in the slope of the peat 14 c ages 4 sampling error these results shed doubt on the assumed continuities in theoretical peat accumulation models both mire stratigraphy and changing accumulation rates can be explained in qualitative hydrological terms more evidence for a previously discovered reservoir effect in bog deposits is presented though the physical biological mechanisms remain uncertain

dating the glen garry tephra a widespread late holocene marker horizon in the peatlands of northern britain the distal icelandic tephra known as the glen garry layer has been dated by ams 14c at eight ombrotrophic peat bogs from northern england and scotland the geochemistry of all the tephra layers is consistent with there being only one glen garry tephra rather than two or more from eruptions of the same volcanic source at seven of the sites all in scotland the tephra layer was bracketed by 1 cm contiguous samples below at and above the horizon at the one english site walton moss cumbria a suite of 16 ams dates was applied to a 116 cm section of a peat core containing the tephra the resulting dates were calibrated and wiggle matched using the bcal and bpeat programmes to give an estimated age for the glen garry tephra of 2176 cal bp with a 2 range of 2210 1966 cal bp this 244 year range is an improvement on the 410 years calibrated date range for the date without the wiggle match this age estimate will allow future work on peat profiles and other sediments containing the tephra to use the date as a pinning point in age depth models and obviate the need for radiocarbon dating at this period

early holocene environmental change in the kreekrak area zeeland sw netherlands a multi proxy analysis abstract detailed botanical microfossil and macroremain zoological and geochemical analyses major and trace elements including c al s ca fe p as zn u ba and rare earth elements of organic deposits provide new insights into early holocene environmental change in the kreekrak area southwestern netherlands the age assessment of the record is based on high resolution ams 14 c wiggle match dating wmd for the first time an ams 14 c wmd based chronology covering the late glacial holocene transition and early preboreal is introduced for a site in the netherlands the kreekrak botanical record reflects the end of the younger dryas to early boreal and can be well correlated with pollen records from other sites in the netherlands and belgium the palaeo topography showed that the kreekrak deposits formed in an abandoned channel of the river schelde around ca 11 490 cal bp at the end of the late glacial holocene transition infilling of the lake started with predominantly organic deposits in slowly running water as a result of the warmer climate the area became forested with birch and poplar during the friesland phase ca 11 490 11 365 cal bp biological productivity of the lake and its surroundings increased aquatic vegetation developed in the lake while shrubs of willow reed swamps and grasslands fringed the shores precipitation increased which caused a rise in the lake water table and an increase in the supply of oxic surface river water into the kreekrak lake during this period the kreekrak lake was fed by inflowing river water run off precipitation and seepage of fe rich groundwater around ca 11 435 cal bp the water became stagnant probably as result of a total cut off of the river channel inflow of river water ceased while the supply of reduced fe rich groundwater became dominant during the rammelbeek phase ca 11 365 11 250 cal bp the climate was more continental and the abundance of grasslands and open herbaceous vegetation increased biological productivity remained high in the lake the supply of fe rich groundwater continued the water level slightly decreased but aquatic vegetation remained present at the end of the rammelbeek phase a sudden reduction in the supply of fe rich reduced groundwater caused a lowering of the groundwater level in the area resulting in the development of a hiatus due to this hiatus the late preboreal 11 250 10 710 cal bp is absent from the record during the early boreal 10 710 10 000 cal bp the landscape became densely forested and accumulation of peat in the former lake resumed due to a slowly rising groundwater level the boreal was a relatively stable period with low sedimentation rates the combination of palaeobotanical and geochemical analyses in the kreekrak record shows a close interrelation between landscape development and geochemistry it appears that the environmental development of this area during the late glacial holocene transition and early holocene was largely influenced directly or indirectly by major climatic changes that occurred during this period which determined local phenomena such as the composition and density of the vegetation occurrence of seepage and river activity further research of this type has the potential to develop the application of major and trace element geochemistry in palaeoenvironmental reconstructions

carbon 14 wiggle match dating of peat deposits advantages and limitations carbon 14 wiggle match dating wmd of peat deposits uses the non linear relationship between c 14 age and calendar age to match the shape of a series of closely spaced peat c 14 dates with the c 14 calibration curve the method of wmd is discussed and its advantages and limitations are compared with calibration of individual dates a numerical approach to wmd is introduced that makes it possible to assess the precision of wmd chronologies during several intervals of the holocene the c 14 calibration curve shows less pronounced fluctuations we assess whether wiggle matching is also a feasible strategy for these parts of the c 14 calibration curve high precision chronologies such as obtainable with wmd are needed for studies of rapid climate changes and their possible causes during the holocene copyright c 2004 john wiley sons ltd

a millennial record of environmental change in peat deposits from the misten bog east belgium in this study palaeoenvironmental changes recorded in the top metre of a peat profile misten bog east belgium were investigated using a multiproxy approach proxies include bulk density ti and si content pollen macrofossils d13c on specific sphagnum stems and d13ced18o on sphagnum leaves a highresolution chronology was generated using 210pb measurements and 22 14c ams dates on carefully selected sphagnum macrofossils d13c only records large change in mire surface wetness this is partly due to the fact that the core was taken from the edge of a hummock which may make it difficult to track small isotopic changes the d13c signal seems to be dependent upon the sphagnum species composition for example a change between sphagnum section cuspidata towards sphagnum imbricatum causes a significant drop in the d13c values on the whole the c and o isotopes record two shallow pool phases during the 8the9th and the 13th centuries pollen and atmospheric soil dust asd fluxes records increased human occupation in the area there may be some climatic signals in the asd flux but they are difficult to decipher from the increasing human impact land clearance agriculture during the last millennium the variations in the proxies are not always synchronous suggesting different triggering factors temperature wetness windiness for each proxy this study also emphasizes that compared to studies dealing with pollution using geochemical proxies palaeoclimatic inferences from peat bogs need as many proxies as possible together with highly accurate and precise age models in order to better understand climate variability and their consequences during the holocene

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

improving the time control of the subboreal subatlantic transition in a czech peat sequence by 14c wiggle matching to achieve an optimal time control for a late subboreal to early subatlantic peat sequence from pancavska louka in the czech republic different strategies are applied to convert a series of radiocarbon dates into a calendar time scale the methods of selection and preparation of the samples for ams 14c dating are presented the results of calibrating single radiocarbon dates are compared with a 14c wiggle match strategy as the accumulation rate of the peat was not constant the concentrations of arboreal pollen are used to estimate the accumulation rate changes and to correct for these changes the resulting time control represents the best solution for this peat sequence with the methods currently available

regional climate change from peat stratigraphy for the mid to late holocene in central ireland at the millennial scale bog surface wetness bsw records show a clear holocene climate event stratigraphy with major phases comparable with other regional climate proxies such as chironomid inferred temperature records moving towards the centennial scale however and towards the limits of chronological certainty within the records regional differences are apparent which likely reflect the more heterogeneous precipitation patterns which occur on shorter timescales the bsw data presented in this paper are reconstructed from testate amoebae assemblages from central ireland and are compared with other regional records the results suggest that this region is in phase with the north of ireland in terms of timings and durations of climate change but the comparisons are less clear with a stacked and tuned record from northern britain that shows an apparent offset compared to the irish records this may reflect variations in past regional precipitation or be a function of the tuning and stacking process the broad phases of comparison between the irish records and the extension of the central irish record back to 6000 cal bp allow comparisons with low frequency temperature reconstructions from chironomids which also show a broad level of correlation with cooler temperatures relating to wetter bsw at centennial to millennial timescales

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

solar modulation of cosmogenic nuclide production over the last millennium comparison between 14c and 10be records for about the last 30 years it has been recognized that the high frequency component of the tree rings 14c 12c record is dominated by the modulation of the cosmic ray flux by the solar wind in particular it has been demonstrated that the three most recent periods of low sunspot occurrence were characterized by high values of atmospheric 14c 12c during the last millennium other periods of high 14c 12c values were observed but their solar origin is still debatable in the present work we compare these fluctuations with an independent record of cosmogenic 10be measured in ice from the south pole to check the solar origin of the observed 14c 12c variations in order to compare quantitatively the results obtained on 10be and 14c it is necessary to take into account the different behaviour of these two cosmogenic isotopes and especially the damping effect of the carbon cycle in the case of 14c as an input to a 12 box numerical model we used the relative fluctuations of the 10be concentrations record measured in south pole ice and converted it into a synthetic 14c record we took into account the fact that 10be modulation is enhanced in polar regions due to the orientation of the geomagnetic field as expected the fluctuations of the modelled 14c record are much smaller a factor of 20 than those observed for the raw 10be record in addition the variations are smoother and shifted in time by a few decades the 10be based 14c variations closely resemble the 14c measurements obtained on tree rings r 0 81 in particular it is easy to identify periods of maximal 14c 12c which correspond to solar activity minima centred at about 1060 1320 wolf 1500 sporer 1690 maunder and 1820 dalton yr a d cross correlation calculations suggest that there is no significant lag between the 10be based 14c and the tree ring 14c records our study strongly suggests the dominance of the solar modulation on the cosmonuclide production variations during the last millennium

late holocene climate change and human impact recorded in a south swedish ombrotrophic peat bog abstract a peat core from a raised bog in southern sweden was examined plant macrofossils pollen non pollen microfossils colorimetric humification carbon nitrogen ratios bulk densities loss on ignition to investigate the effects of climate change and human impact on the plant species composition and carbon accumulation of the peat forming vegetation 14c wiggle match dating was applied for fine resolution dating cooling at the start of the little ice age was reflected by a decline of thermophilous trees from the pollen record between ca cal ad 1275 1590 coinciding with increases in atmospheric 14c pointing to decreases of solar activity wolf and sporer minimum human impact also decreased later the effect of human impact was clearly visible in the form of a black brown decomposed peat layer the top of which marks a gap of more than 300 years artificial drainage probably caused secondary decomposition and oxidation of the peat from ca cal ad 1960 the water table of the peat bog was restored following construction of a road and raised bog vegetation regenerated

submillennium scale migrations of the rainforest savanna boundary in colombia 14c wiggle matching and pollen analysis of core las margaritas abstract we present the 11 150 cal yr long pollen record laguna las margaritas 3 23 n 73 26 w 290 m altitude located at a site sensitive to climatic change near the transition from the amazonian rainforest to the savanna of the llanos orientales in colombia in the 10 m long core nine ams 14 c bulk samples show ages from 9760 60 to 854 36 bp and provide initial time control thirty one additional ams 14 c samples of selected macrofossils provide time control from 6250 to 4050 cal bp for this interval precise time control was obtained by 14 c wiggle match dating from 11 150 to 9100 cal bp grass savanna dominated the landscape while gallery forest along the drainage system was poorly developed water availability was lower than today and the length of the dry season longer from 9100 to 7330 cal bp gallery forest expanded pointing to wetter conditions from 7330 to 5430 cal bp savanna was increasingly replaced by forest but with alternating abundance of both vegetation types from 5430 to 2500 cal bp forest and wooded savanna dominated the western llanos orientales suggesting high precipitation rates expansion of mauritia palm forest at 2500 cal bp reflects increasing water availability and stagnant water environments increasing savanna between 2500 and 1000 cal bp may represent a combined natural and anthropogenic signal development from open savanna to forest during the middle holocene is synchronous with a decreasing caloric seasonality and a southward migration of the intertropical convergence zone suggesting that the large scale climatic and vegetational change in the colombian savannas is precession forced high frequent migration of the savanna rainforest boundary started around 6000 cal bp and continued at least to 3000 cal bp precipitation regimes in northwest and northeast south america seem opposite dry conditions in the colombian savanna area seem to reflect a la nina setting of the climate system wet conditions reflect an el nino setting 14 c fluctuations reflect changes of solar activity and we tested the hypothesis that 14 c fluctuations correspond to climatic and vegetational change for the interval 6250 to 4050 cal bp we applied 14 c wiggle match dating wmd i e matching a series of radiocarbon ages in 14 c bp from the sediment with the dendrochronology based calibration curve and we also wiggle matched the pollen record vs the 14 c record in this first attempt in a neotropical ecosystem we could not find unambiguous support that changes in solar activity did trigger climatic and vegetational change in the savannas of the llanos orientales

a possible solar pacemaker for holocene fluctuations of a salt marsh in southern italy abstract this study is aimed at verifying the possible influence of solar activity on the coastal vegetation development in the tavoliere plain south adriatic region italy between 6350 and 4000 cal bp when regular fluctuations of halophilic vegetation are recorded by pollen a wavelet analysis applied to the percentage values of glasswort vegetation is consistent with periodicities of solar activity and other palaeoenvironmental and palaeoclimate proxies in the literature a comparison of salt marsh pollen indicators salicornia type and ruppia maritima with the 10be dataset from the greenland ice core gisp2 on the basis of their independent chronologies reveals a strong visual correlation indicating that the minima of salt marsh percentages match minima in the 10be curve corresponding to solar activity maxima associated with warm and arid phases at the middle latitudes the tavoliere salt marsh appears to have contracted during the arid warm phases associated to maxima of solar activity and to have expanded during the wet cold phases of solar minima this coastal area characterized by a very flat topography and arid climate appears to have been very sensitive to even minor hydrological and climate changes changes of solar activity determining extensive environmental transformations were also possibly responsible for the abandonment of the human coastal settlements of one of the most important neolithic archaeological districts of italy

simulation of holocene cooling events in a coupled climate model three potential mechanisms behind centennial scale holocene cooling events are studied in simulations performed with the coupled climate model ecbilt clio 1 internal variability 2 solar forcing and 3 freshwater forcing in experiments with constant preindustrial forcings three centennial scale cooling events occur spontaneously in 15 000 years these rare events represent an unstable internal mode of variability that is characterised by a weaker thermohaline circulation a more southward location of the main site of deep water formation expanded sea ice cover and cooling of 101c over the nordic seas this mode is visited more frequently when the climate is cooled by abruptly reducing the solar constant by 5 or 3 wm 2 prescribing a solar forcing of the same magnitude but following a sinusoidal function with a period of 100 or 1000 years does not result in any centennial scale cooling events the latter forcing does however result in more frequent individual cold years in the north atlantic region that are related to local weakening of the deep convection and sea ice expansion adding realistic freshwater pulses to the labrador sea is also able to trigger centennial scale cooling events with temperature anomalies resembling proxy evidence for the cooling event at 8 2 kyr bp suggesting that freshwater forcing is a valid explanation for early holocene cooling events r 2007 elsevier ltd all rights reserved

late holocene human impact and climate change recorded in a north swedish peat deposit abstract a peat core from a mire with poor fen lawns and ombrotrophic hummock strings in northern sweden was examined plant macrofossils pollen non pollen microfossils testate amoebae colorimetric humification carbon nitrogen ratios bulk densities loss on ignition to investigate the effects of climate change and human impact on the plant species composition and peat accumulation of the peat forming vegetation during the last 1700 yr 14 c wiggle match dating was applied for high precision dating the lappmyran region was dominated by pinus and picea forest changes in land use patterns and population density were visible in the pollen record of the regional vegetation juniperus and rumex acetosa type pollen indicated the presence of grazed land in the area between ad 1500 and 1950 the vegetation at the coring spot gradually became ombrotrophic the local plant and testate amoebae compositions reflect changes in surface wetness caused by changes in precipitation and the internal dynamics of the bog a wet interval was observed during the maunder minimum of solar activity the presence of drepanocladus fluitans indicates less ombrotrophic conditions during this period probably caused by the inflow of minerogenic water from upslope owing to increased precipitation the reconstructed water table shows agreement with precipitation measurements which were available since ad 1860

molecular and isotopic stratigraphy in an ombrotrophic mire for paleoclimate reconstruction a 40 cm deep sphagnum dominated peat monolith from bolton fell moss in northern england was systematically investigated by lipid molecular stratigraphy and compound specific 13c and d analysis using gas chromatography gc gc mass spectrometry gc ms gc combustion isotope ratio ms gc c irms and gc thermal conversion irms gc tc irms techniques 210pb dating showed the monolith accumulated during the last ca 220 yr a period encompassing the second part of little ice age while the distributions of lipids including n alkan 1 ols n alkan 2 ones wax esters sterols n alkanoic acids alkandioic acids and hydroxy acids display relatively minor changes with depth the cooler climate event was recorded in the concentrations of n alkanes and organic carbon cpi values of n alkanes and n alkanoic acids and the ratio of 5 n alkylresorcinols sterols superimposed on the fossil fuel effect the relatively cooler climate event was also recorded by 13c values of individual hydrocarbons especially the c23n alkane a major compound in certain sphagnum spp the d values of the c29 and c33n alkanes correlated mainly with plant composition and were relatively insensitive to climatic change in contrast the c23n alkane displayed variation that correlated strongly with recorded temperature for the period represented by the monolith agreeing with previously reported deuterium records in tree ring cellulose spanning the same period in scotland germany and the usa with more negative values occurring during the second part of little ice age these biomarker characteristics including the compound specific 13c and d records provide a new set of proxies of climatic change potentially independent of preserved macrofossils which will be of value in deeper sections of the bog where the documentary records of climate are unavailable and humification is well advanced

information on past solar activity and geomagnetism from 10 be in the camp century ice core a nearly continuous record of the concentration of 10be from ice core data is compared with the tree ring derived record for 14c over the same period and it is found that short term trends in these data sets provide a record of solar activity no definitive relationship between the long term trends and the geomagnetic dipole moment is found

palaeoclimatic and archaeological evidence for a 200 yr recurrence of floods and droughts linking california mesoamerica and south america over the past 2000 years conspicuous grey clay rich flood deposits in the predominantly olive varved sediment in the central santa barbara basin california were dated via varve counting to c ad 212 440 603 1029 1418 and 1605 the 200 yr quasi periodicity and the timing of individual floods match time periods of known supraregional climatic changes and the documented 200 yr periodicity in palaeoclimate records elsewhere the floods of c ad 440 and ad 1418 occurred during global reorganizations of atmospheric circulation cold spells seem to have accompanied the floods of c ad 1029 and ad 1605 california floods and other palaeoclimate records suggest that expressions of regional climates are modulated by solar variability with a 200 yr periodicity our compilation of palaeoclimatic and mesoamerican and south american archaeological records provides evidence that palaeoenvironmental and cultural changes were often coincident within their respective dating uncertainties and occurred in 200 yr steps the matching patte

holocene climate and seasonality of shell collection at the dundas islands group northern british columbia canada a bivalve sclerochronological approach article i nfo to analyze environmental changes and the seasonality of shell collection in british columbia during the ho locene oxygen isotopes were measured from modern and archeological 1337 7438 cal yr bp shells of the butter clam saxidomus gigantea 1697 discrete isotope samples were taken from two modern and 27 arche ological shells with a high temporal resolution sub seasonal up to daily archeological shells were collected from five shell midden sites on the dundas islands group northern british columbia canada the oxygen iso tope data reveal clear annual cycles with the most positive 18 oshell values occurring during the cold season slower growth annual growth line formation and the most negative 18 oshell values during the warm sea son period of faster growth whereas the most positive 18 oshell values remained relatively constant throughout the holocene the warm season 18 oshell values reflected considerable variability summer values observed in the early and late holocene became approximately 1 more negative around 2500 3000 and 5500 6000 bp implying lower salinity during the mid holocene variations in the oxygen isotopic composi tion of marine shells reflect changes in temperature and salinity such large changes in 18 oshell are unlikely being caused by temperature changes alone furthermore the large annual 18