intra and inter annual growth rate of modern stalagmites we measure the factors that determine growth rate temperature drip rate calcium ion concentration for 31 waters that feed stalagmites within six cave systems throughout europe water samples were collected at a frequency of at least 1 month to permit the modelling of both inter and intra annual growth rate variations utilising the theory of wolfgang dreybrodt chem geol 29 1980 89 105 chem geol 32 1981 237 245 dreybrodt w 1988 processes in karst systems springer verlag berlin 288 pp inter annual growth rates were measured using the stalagmites that were associated with the analysed water samples growth rate was determined from annual lamina counting specific time markers within the stalagmites and location of bomb 14c when compared to theoretically predicted values a good agreement between theoretical and measured stalagmite growth rates is observed r2 0 69 when compared to site climate and geochemical parameters a good correlation is observed between measured growth rate and mean annual temperature for five sites r2 0 63 and dripwater calcium content r2 0 61 but not drip rate r2 0 09 the good correlation with both calcium and temperature is due to soil co2 production being primarily determined by surface temperature and soil moisture however when we compare our data to that in the grotte de clamouse a site that has little soil cover we observe that the growth rate temperature relationship breaks down due to either the lack of soil co2 production or prior calcite precipitation intra annual data demonstrates that maximum growth rate occurs when calcium concentrations are high and that this occurs under different seasons depending on the hydrology of each site our results demonstrate a stronger dependence of intra annual stalagmite growth rate on dissolved calcium ion concentrations than drip rate for the range of drip rates investigated here 0 01 t 2drip s 1 but for lower drip rates this factor becomes important in controlling growth rate we suggest that for well monitored and understood sites stalagmite growth rate variations can provide useful information for palaeoclimate reconstruction

late pleistocene paleoclimate in the black hills of south dakota from isotope records in speleothems abstract two coeval speleothems from the black hills are used to investigate 18 o and 13 c variations within reed s cave and reconstruct climate during the wisconsin glacial period from 82 000 to 24 000 years ago variation in growth rates between the two speleothems reveals a strong control of hydrology and surface vegetation on isotopic variability and response of 18 o to climate high resolution 18 o and 13 c data show that local environmental conditions can produce an offset of 18 o values of up to 4 in coeval speleothems but still reveal important climate events the transition from warmer to cooler periods results in an increase in 18 o of calcite 18 o ct in sample rc2 while in sample rc20 another equilibrium deposit coeval to part of the rc2 record 18 o ct is offset from rc2 by between 0 and 3 5 and shows much higher frequency isotopic variation speleothem rc2 records interglacial glacial transitions and interstadial events that are also present in speleothems from north america and europe spectral analysis of the 18 o ct records for both speleothems reveals periodicity at 1000 to 2000 years similar to millennial scale variability seen in the north atlantic sediments and the greenland ice cores

quantitative assessment of landform equifinality and palaeoenvironmental reconstruction using geomorphic models abstract we present results from a study of post glacial alluvial fan evolution in new zealand in which a series of 83 000 numerical simulations of fan formation were conducted within a monte carlo framework in order to evaluate the potential for reconstructing past environmental conditions by matching simulated and observed fan morphologies our results indicate that simulations based on a wide range of model boundary conditions and internal process parameterisations are able to reproduce the observed fan characteristics such equifinal behaviour is a product of an imposed limit on fan progradation and associated autogenic feedbacks which drive fan entrenchment even in the absence of external changes in water or sediment supply we find little evidence that the majority of preserved fan terraces that formed post entrenchment did so during periods of higher than average discharge or sediment supply to the fan apex or that evidence for significant changes in sediment supply associated with major climate shifts are likely to be preserved in the current fan morphology these results illustrate the difficulties that are inherent in the interpretation of alluvial landforms as records of past environmental conditions they also highlight the need for more rigorous quantification of uncertainties in field and model based interpretation of landscape responses to environmental change

laurentide ice sheet instability during the last deglaciation the factors leading to the full retreat of ice sheets during deglaciation are debated numerical modelling suggests that the laurentide ice sheet retreated only after a threshold for warming and radiative forcing was passed in the holocene

tectonic and kinematic study of a strike slip zone along the southern margin of central ovda regio venus geodynamical implications for crustal plateaux formation and evolution the tectonic system of the southern margin of central ovda regio a crustal plateau which straddles venus equator has been interpreted as a dextral strike slip array on the basis of evidence clearly identifiable as are riedel fracture patterns of different scales en echelon folds and brittle strike slip faults this transcurrent regime developed two main shear belts inner and outer on respectively thicker and thinner crust whose minimum dextral displacement has been estimated in 30 50 km since the up or downwelling models for plateau formation cannot easily explain tectonic shears of this magnitude along their margins an alternative hypothesis has been built which stands on the proposed collisional belt which could form ovda northern border king et al 1998 lunar planet sci conf 29 abstract 1209 tuckwell and ghail 2002 lunar planet sci conf 33 abstract 1566 within this framework the shear would represent a transcollisional transcurrent zone similar to the strike slip zones produced in the foreland of the himalayas tibet collision front eastern ovda would be an independent area of thickened crust pushed to the sse by the northern collision with the deformation concentrated at its margins and experiencing a shear strain on its southern margin none of the data however either supports nor helps to discard theoretical subduction events as a cause of the collision on the contrary image relationships could be interpreted as evidence that the main shear deformation took place during the last global resurfacing event on the planet

oceanographic and climatic changes over the past 160 000 years at deep sea drilling project site 594 off southeastern new zealand southwest pacific ocean high resolution textural carbonate microfossil and oxygen 18o and carbon 13c stable isotopic analyses are presented for the late quaternary isotopic stages 1 to 6 interval of a core at deep sea drilling project site 594 situated just south of the present subtropical convergence in northernmost subantarctic surface waters on the southern flank of chatham rise in the southwest pacific downcore alternations of pelagic and hemipelagic oozes correspond to interglacial and glacial episodes respectively interglacial oozes contain a northern subantarctic assemblage of planktonic foraminifera with rare cool subtropical species while glacial oozes are characterized by species typical of southern most subantarctic waters and include radiolaria with affinity for antarctic waters the planktonic 18o record for the site supports a 3 6 c temperature change in near surface waters between interglacial and glacial stages and indicates that during stage 5e the near surface waters were about 1 c warmer than at present a pronounced cooling during stage 5d matches that of the vostok ice core d record and negative excursions at the end of stages 2 and 6 support a southern latitude warming preceding northern hemisphere deglaciation benthic foraminifera typical of cold intermediate to deep waters can increase dramatically in abundance in the hemipelagic ooze intervals when 18o results suggest a temperature drop in glacial stage bottom waters of 2 4 c possibly a result of upward displacement of antarctic intermediate water by circumpolar deep water at the site the foraminiferal 13c records support a reduced influence of north atlantic deep water in the southwest pacific during glacial stages when nutrient enhancement occurred in both bottom and surface waters despite the pronounced changes between interglacial and glacial conditions inferred at site 594 contributed to by a substantial northward shift by at least 5 of latitude in the position of the antarctic convergence south of new zealand during glacial episodes we conclude that the subtropical convergence remained locked to chatham rise approximately 44 s throughout stages 1 to 6 major compression of the intervening belt of subantarctic water during glacial episodes and the associated very steep thermal gradients and intensified atmospheric and oceanic circulation patterns that developed in this part of the southwest pacific account for the harsh frigid environment reported for on land southern new zealand at these times

climate and vegetation history of the midcontinent from 75 to 25 ka a speleothem record from crevice cave missouri usa four missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago ka the thorium 230 dated records reveal that between 75 and 55 ka the midcontinental climate oscillated on millennial time scales between cold and warm and vegetation alternated among forest savanna and prairie temperatures were highest and prairie vegetation peaked between 59 and 55 ka climate cooled and forest replaced grassland at 55 ka when global ice sheets began to build during the early part of marine oxygen isotope stage 3

timing of the antarctic cold reversal and the atmospheric co2increase with respect to the younger dryas event the transition from the last glacial to the holocene is a key period for understanding the mechanisms of global climate change ice cores from the large polar ice sheets provide a wealth of information with good time resolution for this period however interactions between the two hemispheres can only be investigated if ice core records from greenland and antarctica can be synchronised accurately and reliably the atmospheric methane concentration shows large and very fast changes during this period these variations are well suited for a synchronisation of the age scales of ice cores from greenland and antarctica here we confirm the proposed lead of the antarctic cold reversal on the younger dryas cold event the antarctic cooling precedes the younger dryas by at least 1 8 kyr this suggests that northern and southern hemispheres were in anti phase during the younger dryas cold event a further result of the synchronisation is that the long term glacial interglacial increase of atmospheric co 2 was not interrupted during the younger dryas event and that atmospheric co 2 changes are not necessarily dominated by changes in the north atlantic circulation

elevated and variable values of 13c in speleothems in a british cave system 13c isotope variations in speleothems have been investigated for samples from the british isles where plants which use the hatch slack or c4 photosynthetic pathway are not present the range of 13c expected in speleothem carbonate formed in isotopic equilibrium with soil co2 derived from the overlying c3 vegetation should thus fall in the range 12 to 6 forty one actively growing speleothem samples from low discharge sites were analysed from stump cross caverns yorkshire england ten percent have 13c greater than 6 in addition a large range of 13c was observed 8 06 1 38 a 1 variability of 17 with adjacent samples having 13c differing by a maximum of 4 74 similar findings were obtained from a review of analyses of late quaternary speleothem samples from the british isles with 75 of flowstone samples and 57 of high flow stalagmite samples exhibiting elevated 13c three possible processes are proposed as possible causes of elevated 13c in speleothems firstly fractionation may occur between the stalactite and stalagmite due to evaporation or degassing secondly degassing of the groundwaters may have occurred within the aquifer before reaching the cave void allowing release of some co2 from the water whilst remaining saturated in calcium finally the elevated 13c may be due to short water residence times in the soil such that equilibrium between soil water and soil co2 is not reached evidence presented here demonstrates that any one of these mechanisms may be important in the karst areas of the british isles caution is needed before interpreting the 13c signal within speleothems in terms of palaeovegetation

towards a climate event stratigraphy for new zealand over the past 30 000 years nz intimate project it is widely recognised that the acquisition of high resolution palaeoclimate records from southern mid latitude sites is essential for establishing a coherent picture of inter hemispheric climate change and for better understanding of the role of antarctic climate dynamics in the global climate system new zealand is considered to be a sensitive monitor of climate change because it is one of a few sizeable landmasses in the southern hemisphere westerly circulation zone a critical transition zone between subtropical and antarctic influences new zealand has mountainous axial ranges that amplify the climate signals and consequently the environmental gradients are highly sensitive to subtle changes in atmospheric and oceanic conditions since 1995 intimate has through a series of international workshops sought ways to improve procedures for establishing the precise ages of climate events and to correlate them with high precision for the last 30 000 calendar years the nz intimate project commenced in late 2003 and has involved virtually the entire new zealand palaeoclimate community its aim is to develop an event stratigraphy for the new zealand region over the past 30 000 years and to reconcile these events against the established climatostratigraphy of the last glacial cycle which has largely been developed from northern hemisphere records e g last glacial maximum lgm termination i younger dryas an initial outcome of nz intimate has been the identification of a series of well dated high resolution onshore and offshore proxy records from a variety of latitudes and elevations on a common calendar timescale from 30 000 cal yr bp to the present day high resolution records for the last glacial coldest period lgcp including the lgm sensu stricto and last glacial interglacial transition lgit from auckland maars kaipo and otamangakau wetlands on eastern and central north island marine core md97 2121 east of southern north island speleothems on northwest south island okarito wetland on southwestern south island are presented discontinuous fragmentary records comprising compilations of glacial sequences fluvial sequences loess accumulation and aeolian quartz accumulation in an andesitic terrain are described comparisons with ice core records from antarctica epica dome c and greenland gisp2 are discussed a major advantage immediately evident from these records apart from the speleothem record is that they are linked precisely by one or more tephra layers based on these new zealand terrestrial and marine records a reasonably coherent regionally applicable sequence of climatically linked stratigraphic events over the past 30 000 cal yr is emerging three major climate events are recognised 1 lgcp beginning at ca 28 000 cal yr bp ending at termination i ca 18 000 cal yr bp and including a warmer and more variable phase between ca 27 000 and 21 000 cal yr bp 2 lgit between ca 18 000 and 11 600 cal yr bp including a lateglacial warm period from ca 14 800 to 13 500 cal yr bp and a lateglacial climate reversal between ca 13 500 and 11 600 cal yr bp and 3 holocene interglacial conditions with two phases of greatest warmth between ca 11 600 and 10 800 cal yr bp and from ca 6 800 to 6 500 cal yr bp some key boundaries coincide with volcanic tephras copyright 2007 john wiley sons ltd

late quaternary paleoclimate in the eastern mediterranean region from stable isotope analysis of speleothems at soreq cave israel abstract the eastern mediterranean continental paleoclimate during the past 25 000 years was determined by a high resolution petrographic stable isotopic and age study of speleothems from soreq cave israel 18o 13c trends indicate that all speleothems older than 7000 yr formed under conditions that differ from those of today the period from 25 000 to 17 000 yr b p was characterized by the highest 18o and 13c values which indicate deposition at temperatures of 12 16 c annual rainfall of 300 450 mm and vegetation typical of a mixed c3 c4type from 17 000 to 10 000 yr b p deglaciation in northern europe 18o values dropped progressively correlative with warming 2 3 c and a gradual increase in precipitation a simultaneous decrease in 13c gives a range expected for c3 type vegetation this period also shows significant 18o and 13c spikes which are correlatable with global events e g heinrich events and the younger dryas stade the speleothems that grew between 10 000 and 7000 yr b p have a unique petrography showing irregular thin laminae of various colors and much detritus they have the lowest 18o corresponding to 1000 mm rain coupled with the highest 13c caused by flooding events which stripped the soil cover from 7000 to 1000 yr b p conditions became closer to those of today this study demonstrates that global events which were recognized in northern europe and north africa are also evident in the eastern mediterranean and are reflected principally by large changes in the rainfall rate

stable isotope stratigraphy of holocene speleothems examples from a cave system in rana northern norway high precision tims u series dates and continuous stable oxygen and carbon isotope profiles of a 4000 year stalagmite record from rana northern norway are presented and compared with data from two other speleothems from the same cave the dating results yield ages from 3875 34 to 296 3 years before ad2000 with 2s errors from 0 5 to 1 the overall growth rate is 35 mm ka corresponding to a temporal resolution of 29 years mm the stalagmite is tested for isotopic equilibrium conditions where all hendy tests except one indicate isotopic equilibrium or quasi equilibrium deposition both the stable oxygen and carbon isotope records reveal a strong and abrupt enrichment in the near top measurements this corresponds in time to the opening of a second cave entrance in the late 1960s which caused changes in the cave air circulation the stable oxygen isotope signal is enriched compared to the modern value over the last 300 years indicating a negative response to temperature changes likewise the stable carbon isotope record is enriched in this period however both of the stable isotope records are shown to be significantly enriched compared to the isotope ranges displayed by other stalagmites in the same cave and this questions the reliability of the proxy records derived from the presented stalagmite still a general good correspondence of large scale fluctuations is found between the three stable oxygen isotope records from this cave the stable carbon isotope records show large variations within the cave and are believed to be governed by soil zone conditions percolation pathways and possibly driprates q 2001 elsevier science b v all rights reserved

warm season temperatures since 1600 bc reconstructed from tasmanian tree rings and their relationship to large scale sea surface temperature anomalies we describe an improved tree ring reconstruction of mean warm season november april temperatures for tasmania from huon pine this record extends back to 1600 bc and is based on a tree ring chronology that was processed to retain as much low frequency variance as possible the resulting reconstruction explains 46 6 of the variance and verifies significantly when compared to withheld instrumental data cross spectral analysis of actual and estimated temperatures over the 1886 1991 common period indicates that most of the unexplained variance is at periods 12 years the squared coherency ranges between 0 6 0 8 and the cross spectral gain indicates that the amplitude of the reconstruction is a nearly unbiased estimate of the true temperature amplitude therefore this reconstruction should be especially useful for studying multi decadal temperature variability in the tasmanian sector of the southern hemisphere over the past 3592 years to this end we examined the time evolution of low frequency temperature amplitude fluctuations and found evidence for a 35 amplitude reduction after ad 100 that persisted until about ad 1900 since that time the low frequency temperature amplitude has systematically increased we also show how this reconstruction is related to large scale sea surface temperatures sst in the indian ocean and eastward to the dateline pointwise correlations between the tasmanian record and ssts reveal a relationship that extends across the southern indian ocean and towards the arabian sea this pattern is largely determined by inter decadal temperature variability with correlations in this 10 year bandwidth commonly exceeding 0 6 over most of the southern indian and southwestern pacific sectors a rotated empirical orthogonal function analysis reveals that the pattern of pointwise correlations found between the temperature reconstruction and ssts is largely explained by the linear combination of three orthogonal modes of sst variability

speleothem dates quaternary terraces and uplift rates in new zealand previous isotopic research on calcite stalagmites stalactites and flowstones speleothems from new zealand caves has focused on palaeotemperature reconstruction1 2 i report here the use of 230th 234u and 14c age data from speleothems to investigate the relationships between cave levels emerged coastal terraces and uplift rates in the north west of the south island of new zealand at least seven terraces provisionally assigned to various stages in the quaternary are known to occur to at least 200m above sea level3 4 the terraces sometimes cut across limestones which contain caves formed in association with past sea levels uplift followed by water table lowering and abandonment of cave passages by active streams permitted speleothem deposition dating of these deposits gives a minimum age for the cave level and hence also for any terrace to which it may be related while successive dates at different levels yield an uplift rate for the area data are presented from two localities which suggest differential emergence rates of 0 27 0 28 0 09 mm yr 1 and 0 14 0 05 0 03 mm yr 1 thus re evaluation is required of other largely qualitative evidence on the uplift of these parts of the southern alps5

timing and dynamics of the last deglaciation from european and north african δ13c stalagmite profiles comparison with chinese and south hemisphere stalagmites abstract the last deglaciation and its climatic events such as the bolling allerod ba and the younger dryas yd have been clearly recorded in the 13 c profiles of three stalagmites from caves from southern france to northern tunisia the three 13 c records dated by thermal ionization mass spectrometric uranium thorium method tims show great synchroneity and similarity in shape with the chinese cave 18 o records and with the marine tropical records leading to the hypothesis of an in phase between 15 5 and 16 ka 0 5 ka postglacial warming in the northern hemisphere up to at least 45 n the ba transition appears more gradual in the speleothem records than in the greenland records and the allerod seems warmer than the bolling showing here close similarities with other marine and continental archives a north south gradient is observed in the ba trend it cools in greenland and warms in our speleothem records several climatic events are clearly recognizable a cooler period at about 14 ka older dryas od the intra allerod cold period at about 13 3 ka the yd cooling onset between 12 7 and 12 9 0 3 ka similar to the ba the yd displays a gradual climate amelioration just after its onset at 12 75 0 25 ka up to the preboreal and is punctuated by a short climatic event at 12 15 ka even though the southern hemisphere stalagmite records seem to indicate that the postglacial warming started about 3 ka 1 8 ka earlier in new zealand 41 s and about 1 to 2 ka earlier in south africa 24 1 s large age uncertainties essentially due to slow growth rates make the comparison still perilous the overall 13 c speleothem record seems to follow a baseline temperature increase controlled by the increase in insolation and punctuated by cold events possibly due to the n america freshwater lake discharges

an integrated latest quaternary stage 3 to present paleoclimatic and paleoceanographic record from offshore northern new zealand abstract paleoceanographic and onshore paleoclimatic changes during the last 59 000 yr are established from three deep sea sediment cores off northeast new zealand using an integrated log of sediment texture caco3 content palynology and planktonic and benthic foraminiferal 18o and 13c data together with dated silicic tephras these records from the isotopic stage 4 3 boundary to the present record northern new zealand vegetation history changes in a subsidiary equatorward flow of circumpolar deep water and sea surface temperatures ssts for subtropical water stw between latitudes 36 42 and 35 51 s relative to the holocene isotopically derived ssts record average changes of 2 c 2 c and 2 c for the 59 000 43 000 43 000 24 000 and 24 000 12 000 yr time slices respectively the apparent 2 c warming for the 59 000 43 000 yr period is interpreted to reflect changes in the dominant depth habitat of globigerina bulloides in response to upwelling a 2 c cooling of ssts during isotope stage 2 is interpreted in part to reflect upwelling of cool subsurface water resulting from strong and persistent westerly airflow across new zealand with the concomitant enhanced surface water production of caco3 onshore vegetation consistent with these changes are recorded with full conifer hardwood forest prior to 43 000 yr followed by a change to vegetation implying cooler and drier conditions between 43 000 and 12 000 yr and a subsequent return to full forest during the holocene the sequence of biopelagic and hemipelagic sedimentation observed within these cores reflect oscillation of sea level about a threshold eustatic level that controls the transport of terrigenous detritus offshore local variations and interplay of the regional oceanography and morphology and tectonism of the continental shelf will dictate that relative to present sea level this threshold eustatic sea level will vary in depth and hence age along a continental margin data from the new zealand region reveal an extremely steep meridional thermal gradient across the southern and central new zealand region during the last glaciation with minor cooling of stw to the north apart from localized nearshore upwelling zones but pronounced cooling of subantarctic water to the south of the subtropical convergence zone

speleothem evidence for holocene fluctuations of the prairie forest ecotone north central usa carbon and oxygen isotopic trends from seven midwestern speleothems record significant offsets in the timing of middle holocene vegetation change interactions of dry pacific and moist gulf of mexico air masses maintained a sharp moisture gradient across iowa minnesota and wisconsin such that the arrival of prairie was offset by 2000 years between caves and pollen sites located only 50 km apart oxygen isotopes shift concomitantly with carbon in most cases although these changes are believed to represent increased evaporative enrichment of 18o prior to infiltration during the prairie period

holocene sea level rise and coral reef growth on a tectonically rising coast huon peninsula papua new guinea abstract eighty eight conventional radiocarbon age measurements of corals collected from holocene transgressive reefs at huon peninsula have been published previously but except for 29 dates from a 52 m drillhole the data have not been systematically analysed from these data we show that post glacial reef growth tracked rising sea level keep up growth at huon peninsula from 70 m at 11 200 yr bp the holocene reef emerged about 6300 yr bp in the southeast of the region where uplift rate is highest 3 3 m ka 1 and at about 5950 yr bp in the northwest where uplift rate is 1 9 m ka 1 the uplift process is dominated by metre scale coseismic uplift events the difference in timing of reef emergence between northwest and southeast is related to differences in the stepwise uplift of the two regions although uplift is stepwise the uplift corrected age height data from the dated corals fall within a tight envelope which represents a well defined eustatic sea level curve for the calibrated age interval from 7000 to 13 000 yr bp

ice sheets and sea level of the last glacial maximum this paper outlines the general issues regarding ice sheets and sea level of the last glacial maximum lgm which formed the basis of an epilog project workshop papers in this special issue of quaternary science reviews provide a comprehensive assessment of these issues from the perspective of geological reconstructions of ice sheet extent records of sea level change ice sheet modelling geophysical models of glacial isostatic adjustment and geochemical proxies of ice volume this new assessment has substantially narrowed the uncertainties in the total changes in ice sheets and sea level and their proxies suggesting a net decrease in eustatic sea level at the lgm ranging from 120 to 135 m r 2001 elsevier science ltd all rights reserved

the last glacial maximum and deglaciation in southern south america abstract this paper models the extent of the patagonian icesheet during the last glacial maximum lgm and its subsequent deglaciation it constrains a new coupled icesheet climate numerical model with empirical evidence and simulates the icesheet at the lgm and at stages of deglaciation under lgm conditions an icesheet with a modelled volume slightly in excess of 500 000 km3 builds up along the andes there is a marked contrast between the maritime and continental flanks of the modelled icesheet with positive mass balance exceeding 2 m in the west and declining tenfold to the east modelled ice velocities commonly reach 400 m yr 1 in the western fjords the model is most sensitive to variations in temperature and good agreement between modelled ice extent and empirical evidence was achieved by applying a temperature decrease of 6 c relative to present day temperatures with constant wind fields over the model domain assuming a stepped start to deglaciation modelled ice volumes declined sharply contributing 1 2 m to global sea level 80 of it within 2000 years the empirical record suggests that such a stepped warming occurred around 17 500 17 150 cal yr ago

a stalagmite record of changes in atmospheric circulation and soil processes in the brazilian subtropics during the late pleistocene we present a high resolution 116 000 year carbon stable isotope record from a stalagmite from southern brazil which has been precisely dated using the u series method evaluation of carbon and oxygen isotope ratios together with the speleothem growth history suggest that the carbon isotopic composition of the speleothem is primarily controlled by biogenic co2 supply from the soil which is in turn affected by temperature and secondarily rainfall amount thus the speleothem provides evidence of paleoenvironmental change in southern brazil during the last glacial period predominantly high d 13 c values and low stalagmite growth rates reflect persistent cool conditions during most of the glacial period in subtropical brazil this cooling is probably related to an intensified extratropical circulation with more frequent and intense cold surges reaching a maximum at approximately 19 ky b p this cooling tendency is interrupted during periods of high obliquity values within the full glacial period at 93 85 and 47 40 ky b p and after 19 ky b p when a dramatic decrease in d 13 c marks the deglaciation time in the continent unlike d 18 o the d 13 c record does not exhibit a strong response to precessional forcing instead it shows a strong 40 ky obliquity signal here we propose that local temperature and thus the biological processes in the soil are primarily steered by the gradients of temperature between low and mid high latitudes which influence the meridional heat transport these gradient changes in turn are paced by obliquity r 2006 published by elsevier ltd

cenozoic oceanographic evolution of the sw pacific gateway introduction the region from the southern tip of the campbell plateau to the northern hikurangi plateau spans 21 of latitude equivalent to the distance between southern florida and newfoundland in the north atlantic from new zealand eastwards along the chatham rise to the louisville seamounts is 22 of longitude about 2000 km this region equivalent in area to a major part of the north american basin of the north atlantic now contains 11 stratigraphically useful drill holes seven more than the four of the dsdp sites 277 278 279 and 594 the latest holes ocean drilling program sites 1119 1125 were drilled on odp leg 181 the rst visit of the drilling ship joides resolution to the region in august october 1998 under arduous southern winter conditions fig 1

asynchronous climate change between new zealand and the north atlantic during the last deglaciation climatic fluctuations recorded in antarctica and greenland during the last deglaciation 18 10 ka differ markedly in their timing it remains controversial whether local climate fluctuations recorded in southern mid latitudes relate primarily to northern or southern polar records we present multiproxy results from new zealand that show strong evidence for a minor cooling or slowdown in the rate of warming at the time of the north atlantic late glacial interstadial the younger dryas chronozone in new zealand was a period of resumed warming and increased westerly airflow differences between the hemispheres at this time were probably due to a reorganization of the thermohaline circulation system and associated changes in the meridional temperature gradient

on eustatic sea level history last glacial maximum to holocene abstract this paper addresses the question of the magnitude and time dependence of the globally averaged eustatic rise of sea level that occurred subsequent to the time of last glacial maximum lgm at approximately 21 000 calendar years before present through the analysis of relative sea level rsl histories predicted by a realistic mass conserving and gravitationally self consistent theory of postglacial sea level change it is demonstrated that there are preferred oceanic locations at which this eustatic function is well approximated by local sea level history one such location is the island of barbados in the caribbean sea a site from which a coral based record exists that extends from mid holocene to lgm because of the sea level ambiguity that is inherent to coral based records however it is important that the global ice equivalent eustatic sea level curve inferred on the basis of the barbados data be tested against observations at other locations from which similarly extensive records are also available but which are derived on the basis of sea level indicators which are not subject to the ambiguities inherent to corals it is shown that when the eustatic function employed in the global theoretical model is tuned so as to enable the model to fit the barbados observations where the maximum relative sea level rsl depression is assumed to be near 120 m then the theory misfits the record from the sunda shelf in the indonesian archipelago as well as the record from j bonaparte gulf in northern australia both of these recently published records appear to constrain the lgm low stand of rsl to a value above 120 m the implications of these results for interpretation of the long coral derived records from the huon peninsula of papua new guinea and the island of tahiti are also discussed

southern ocean deglacial record supports global younger dryas abstract in northern hemisphere deglaciation records the transition from the last glacial to the holocene indicates a rapid return to near glacial conditions during the younger dryas whereas their southern hemisphere ice core counterparts record two separate cooling events the antarctic cold reversal and the oceanic cold reversal spatial distribution and relative timing of these events in both hemispheres are central for our understanding of causes and mechanisms of abrupt climate change to date no marine record from the southern mid latitudes conclusively demonstrates that the younger dryas was a significant event in the southern ocean here we present high resolution oxygen isotope and iron content records of a radiocarbon dated sedimentary sequence from the great australian bight which constrains oceanic and atmospheric changes during the last deglaciation oxygen isotopes from planktonic foraminifera indicate two rapid cold reversals between 13 1 and 11 1 kyr bp separated by a brief warming the sedimentary iron content interpreted as a proxy for wind strength indicates a simultaneous change in atmospheric circulation pattern both records demonstrate the existence of cooling events in the southern hemisphere which are synchronous with the northern hemisphere younger dryas cold reversal between 12 9 and 11 5 kyr bp such evidence for the spatial distribution and timing of abrupt climatic fluctuations is essential data for groundtruthing results derived from global climate models

last glacial maximum and hypsithermal in the southern hemisphere abstract a synthesis of the two contrasting climates of the upper quaternary in the southern hemisphere based on continental geological indicators suggests that the antarctic anticyclone is the most important climatic system in the hemisphere according to glaciological and oceanographic studies the antarctic anticyclone covered an area in the lgm that was double of that during the hypsithermal this phenomenon produced a consequent shifting of the climatic belts by approximately 10 of latitude to the north in the lgm and a migration to the south during the hypsithermal oceanic and continental anticyclones were active systems in shaping climates in south america australasia and southern africa these structures were enhanced throughout the lgm provoking generalized droughts and weakened at the hypsithermal permitting more rains in tropical latitudes the results presented here were obtained by integrating our own results with regional and continental syntheses of other authors the paleoclimatic proposals are amply validated by more than 1500 dates in the four continents geological and geomorphological features such as dunefields paleosols fluvial terraces and lake levels were the main tools employed in the work

evidence of younger dryas and neoglacial cooling in a late quaternary palaeotemperature record from a speleothem in eastern victoria australia a calcitic stalagmite collected from a limestone cave in the buchan area of eastern victoria has been dated by three mass spectrometric uranium series analyses two growth phases are represented the older from 13 4 to 10 6 ka and the younger from 3 2 to 2 1 ka oxygen isotope analysis reveals that temperatures were below present day values at all times but particularly cool conditions are indicated between 12 3 and 11 4 ka and neoglacial conditions occurred at about 3 ka the older cold climate event is clearly synchronous with the younger dryas in europe and this is the first time that strong evidence for this event has been found in australia carbon isotope variations are interpreted as indicating changes in plant productivity on the surface and are most likely controlled by variations in summer rainfall they indicate particularly high levels of plant productivity from 11 5 to 11 0 ka 1996 john wiley sons ltd

glacial interglacial sea surface temperature changes across the subtropical front east of new zealand based on alkenone unsaturation ratios and foraminiferal assemblages 0 are compared to those derived from foraminiferal assemblages using the modern analog technique in two of these cores reconstructions of sst in core tops and holocene sediments agree well with modern average summer temperatures of 18 c in subtropical waters and 14 c in subpolar waters with a 4 5 c gradient across the front down core u37 k 0 sst estimates indicate that the regional summer sst was 4 5 c cooler during the last glaciation with an sst of 10 c in subpolar waters and an sst of 14 c in subtropical waters temperature reconstructions from foraminiferal assemblages agree with those derived from alkenones for the holocene in subtropical waters reconstructions also agree with a glacial cooling of 4 to 14 c in contrast reconstructions for subantarctic pre holocene waters indicate a cooling of 8 c with glacial age warm season water temperatures of 6 c thus the alkenones suggest the glacial temperature gradient across the front was the same or reduced slightly to 3 5 4 c whereas foraminiferal reconstructions suggest it doubled to 8 c our results support previous work indicating that the stf remained fixed over the chatham rise during the last glacial maximum however the differing results from the two techniques require additional explanation a change in euphotic zone temperature profiles seasonality of growth or preferred growth depth must have affected the temperatures recorded by these biologically based proxies regardless of the specific reason a differential response to the environmental changes between the two climate regimes by the organisms on which the estimates are based suggests increased upwelling associated with increased winds and or a shallowing of the thermocline associated with increased stratification of the surface layer in the last glaciation index terms 4267 oceanography general paleoceanography 4850 oceanography biological and chemical organic marine chemistry 1050 geochemistry marine geochemistry 4835 4850 1055 geochemistry organic geochemistry keywords paleoceanography sea surface temperature alkenones southern ocean last glacial maximum

cave minerals of the world 2nd edition by carol hill and paolo forti national speleological society huntsville al 463 p isbn number 1 879961 07 5 70 00 think about all of those spectacular displays of mineral crystals that grace the world s mineral museums a great many of the large faceted crystals grew in some sort of cavity over long periods of time such mineral crystals are discovered in vugs pockets and cavities exposed in mines and quarries the conditions under which they were found are very different from the conditions under which they grew the fluids from which they grew are long gone a challenge for mineralogists to deduce from the surviving clues of trace elements isotopes and fluid inclusions now consider a cave it also is a cavity maintaining conditions of constant temperature water vapor pressure and carbon dioxide pressure for long periods of time this is also an environment where minerals can grow but in the case of many caves human observers can watch the growth process in progress some cave minerals appear as large faceted crystals some are nondescript crusts of little beauty but fascinating mineralogy most have formed from flowing dripping and seeping water and thus take on shapes dictated by the idiosyncrasies of the moving water such mineral deposits are known as speleothems stalactites stalagmites flowstone and a host of more intricate shapes hill and forti illustrate speleothems with some spectacular color photographs the authors have solicited contributions from cave photographers all over the world and without exception the

structure and composition of the subalpine forest on mount hauhungatahi north island new zealand during the holocene tree stumps of holocene age were identified and measured at three sites above the present tree line on mount hauhungatahi tongariro national park new zealand wood and peat were radiocarbon dated and annual rings in stump cross sections counted for growth rates comparative measurements were made in three plots in the modern subalpine forests stem densities and basal areas in the ancient forest were within the range of the modern subalpine forest samples the conifers halocarpus biformis phyllocladus asplenifolius var alpinus and libocedrus bidwillii were present in both sets of samples but in different proportions modern forest plots also contained podocarpus hallii and angiosperm trees tree line forest composed predominantly of halocarpus bidwillii reached 1340 m by c 10000 cal bp and c 1390 m by 8700 cal bp these early holocene h bidwillii trees were slower growing and longer lived than the same species in current subalpine forests from c 5400 to 3800 cal bp woody vegetation was ag

climate impact of late quaternary equatorial pacific sea surface temperature variations magnesium calcium data from planktonic foraminifera in equatorial pacific sediment cores demonstrate that tropical pacific sea surface temperatures ssts were 2 8 0 7 c colder than the present at the last glacial maximum glacial interglacial temperature differences as great as 5 c are observed over the last 450 thousand years changes in sst coincide with changes in antarctic air temperature and precede changes in continental ice volume by about 3 thousand years suggesting that tropical cooling played a major role in driving ice age climate comparison of sst estimates from eastern and western sites indicates that the equatorial pacific zonal sst gradient was similar or somewhat larger during glacial episodes extraction of a salinity proxy from the magnesium calcium and oxygen isotope data indicates that transport of water vapor into the western pacific was enhanced during glacial episodes

fine resolution pollen record of late glacial climate reversal from new zealand the temporal relationship between rapid climate shifts in the northern and southern hemispheres at the end of the last glacial is crucial to understanding how the global climate system functions during periods of major transition a detailed southern hemisphere mid latitude pollen record from a climatically sensitive and well dated upland site in new zealand unlike previous interpretations shows clear evidence of late glacial climate changes similar in structure to those in the northern hemisphere including a cooling interval from ca 11 600 to 10 700 14 c yr b p because the cooling interval occurred ca 600 14 c yr before the younger dryas chron our record thus also suggests that some global climatic events during the last deglaciation may have registered earlier in the southern hemisphere

a detailed 31 000 year record of climate and vegetation change from the isotope geochemistry of two new zealand speleothems abstract uranium series dating and stable isotope analyses of two speleothems from northwest nelson new zealand record changes in regional climate and local forest extent over the past 31 000 years oxygen isotope variation in these speleothems primarily represents changes in the meteoric waters falling above the caves possibly responding to latitudinal changes in the position of the subtropical front in the tasman sea seven positive excursions can be identified in the oxygen isotope record which coincide with periods of glacier advance known to be sensitive to northward movement of the subtropical front four glacier advances occurred during oxygen isotope stage 2 with the most extreme glacial conditions centered on 19 000 cal yr b p 2 an excursion in the oxygen isotope record from 13 800 to 11 700 cal yr b p provides support for a previously identified new zealand glacier advance at the time of the younger dryas stade but suggests it began slightly before the younger dryas as recorded in greenland ice cores carbon isotope variations in the speleothems record changes in forest productivity closely matching existing paleovegetation records on the basis of vegetation changes stage 2 glacial climate conditions terminated abruptly in central new zealand from 15 700 to 14 200 cal yr b p evidence of continuous speleothem growth at one site suggests that depression of the local treeline was limited to 600 700 m below its present altitude throughout the last 31 000 years

response of surface water masses and circulation to late quaternary climate change east of new zealand a series of cores from east of new zealand have been examined to determine the paleoceanographic history of the late quaternary in the sw pacific using planktonic foraminiferal data distinct shifts of species can be seen between glacial and interglacial times especially south of chatham rise east of south island foraminiferal fragmentation ratios and benthic planktonic foraminiferal ratios both show increased dissolution during glacials especially isotope stage 2 to the south of chatham rise the present day subtropical convergence appears to be tied to the chatham rise at 44 s but during glacial times this rise separated cold water to the south from much warmer water to the north with an associated strong thermal gradient across the rise we estimate that this gradient could have presented as much as an 8 c temperature change across 4 of latitude during the maximum of the last ice age there is only weak evidence of the younger dryas cool event but there is a clear climatic optimum between 8 and 6 4 ka with temperatures 1 2 c higher than the present day the marine changes compare well with vegetational changes on both south and north island

late pleistocene to holocene composite speleothem 18o and 13c chronologies from south island new zealand did a global younger dryas really exist oxygen and carbon data from eight stalagmites from northwest south island are combined to produce composite records of delta 18 o and delta 13 c from 23 4 ka to the present the chronology is anchored by 43 thermal ionization mass spectrometry tims uranium series ages delta o 18 values are interpreted as having a first order positive relationship to temperature but also to be influenced by precipitation in a complex manner delta c 13 is interpreted as responding negatively to increases in atmospheric co concentration biological activity and precipitation amount six climatic phases are recognized after adjustment of 1 2parts per thousand for the ice volume effect the delta 18 o record between 23 and 18 ka varies around 3 72parts per thousand compared to the holocene average of 3 17parts per thousand late glacial warming commenced between 18 2 and 17 8 ka and accelerated after 16 7 ka culminating in a positive excursion between 14 70 and 13 53 ka this was followed by a significant negative excursion between 13 53 and 11 14 ka of up to 0 55parts per thousand depth that overlapped the antarctic cold reversal acr and spanned the younger dryas yd positive delta 18 o excursions at 11 14 ka and 6 91 6 47 ka represent the warmest parts of the holocene the mid holocene from 6 to 2 ka was marked by negative excursions that coincide with increased glacial activity in the south island a short positive excursion from 0 71 to 0 57 ka was slightly later than the medieval warm period of europe delta c 13 values were high until 17 79 ka after which there was an abrupt decrease to 17 19 ka followed by a steady decline to a minimum at 10 97 ka then followed a general increase suggesting a drying trend to 3 23 ka followed by a further general decline the abrupt decrease in delta values after 17 79 ka probably corresponds to an increase in atmospheric co2 concentration biological activity and wetness at the end of the last glaciation but the reversal identified in the delta 18 o record from 13 53 to 11 14 ka was not reflected in delta 13 c changes the lowest delta 13 c values coincided with the early holocene climatic suboptimum when conditions were relatively wet as well as mild major trends in the delta 18 o c record are similar to the northern hemisphere but second order detail is often distinctly different consequently at the millennial scale a more convincing case can be made for asymmetric climatic response between the two hemispheres rather than synchronicity c 2004 elsevier b v all rights reserved

the oxygen isotopic composition of seawater during the last glacial maximum high resolution oxygen and hydrogen isotope measurements were made on pore fluids from deep sea sediments from sites in the north and south atlantic the data provide direct measurements of changes in the isotopic composition of bottom waters during the last glacial maximum lgm results from ocean drilling program odp site 981 in the north atlantic currently bathed in north atlantic deep water nadw reproduces previous results from the ceara and bermuda rises constraining the glacial interglacial change in 18 o of the deep atlantic to be 0 7 0 8 results from site 984 which is located north of site 981 and at a shallower water depth yield a similar value 0 8 providing insight into the properties of glacial north atlantic intermediate water gnaiw sites from odp leg 177 in the south atlantic span the modern boundary between northern and southern sources of deep water data from the northern site 1088 yield a similar result to sites in the tropical and north atlantic 0 7 at the southern site 1093 located south of the polar front the change is substantially larger 1 1 representing the change in 18 o of southern source waters since the lgm these results confirm previous estimates that the global average change in 18 o of seawater is 1 0 0 1 hydrogen isotopes measured on pore fluids from three sites are consistent with the oxygen isotopes from these locations giving further support to these results at all sites studied the temperature of the deep ocean during the lgm calculated by combining the pore fluid results with oxygen isotope data from benthic foraminifera was within 1 c of the freezing point of seawater

stalagmite growth and palaeo climate an inverse approach abstract the growth of stalagmites is controlled by climatic conditions such as temperature soil activity and precipitation hence a stalagmite stratigraphy reflects fluctuations of palaeo climate conditions on various time scales from annual variations to ice age cycles however no attempt has been made to infer palaeo climate fluctuations from the stratigraphy itself we describe the complicated growth of a stalagmite with a simple mathematical model in which both the growth rate and the equilibrium diameter of stalagmites are functions of palaeo climate variables hence inverting a given stalagmite stratigraphy in terms of growth rate and equilibrium diameter can in principle recover the palaeo climate signal the strongly nonlinear dependence of these two geometrical parameters however limits the success of a formal inversion of stratigraphical data in this paper we explore the resolving power of both growth rate and equilibrium diameter data for the palaeo climate signals temperature carbon dioxide concentration and precipitation we use numerically generated stalagmite stratigraphies as observational data thus we know beforehand the palaeo climate signal contained in the stratigraphic record our results indicate that both variations in carbon dioxide concentrations as a proxy of soil cover and drip interval as a proxy of precipitation can be recovered from the stratigraphy however temperature variations are poorly resolved

hydrological conditions over the western mediterranean basin during the deposition of the cold sapropel 6 ca 175 kyr bp a new oxygen isotope record is reported from a stalagmite collected in the argentarola cave located on the tyrrhenian coast of italy as shown from observations and numerical modeling of n 18 o in modern precipitation the recorded n 18 o variability for this zone is dominated by the amount of precipitation so called amount effect the n 18 o profile measured in the stalagmite is characterized by a prominent negative excursion ca 2 3x between 180 and 170 kyr bp this paleoclimatic feature is interpreted as being due to a relatively wet period which occurred during the penultimate glacial period more precisely during marine isotope stage 6 5 this pluvial phase is shown to correspond chronologically to the deposition of the sapropel event 6 s6 although this particular sapropel event occurred during a cold phase the n 18 o excursion is similar to those corresponding to other sapropels s4 s3 and s2 the evidence for humid conditions during s6 in the western mediterranean basin agrees with previous studies based on deep sea sediment cores taken collectively the data suggest that during sapropel events dilution of ocean surface waters was not restricted to the output of the river nile but was rather widespread over the entire mediterranean sea due to increased rainfall 2002 elsevier science b v all rights reserved

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

new data for the last glacial maximum in great britain and ireland abstract understanding the history of the british and irish ice sheet biis at the last glacial maximum lgm has been advanced by new approaches in particular by cosmogenic nuclide surface exposure dating aminostratigraphy of shelly glacial deposits ams radiocarbon dating and the evidence from continental margin marine cores all of which supersede the previously weak geochronologic control it was formerly believed that great britain and ireland was largely ice free between the last interglacial oxygen isotope sub stage 5e and the late devensian when the lgm occurred as such the biis was effectively out of phase with laurentide and scandinavian ice sheets as well as inferences of ice volume from oxygen isotope stratigraphy the biis during the late devensian maximum was also perceived as having been relatively stationary new evidence shows that the lgm was an important event during the evolution of an earlier biis when the extent of ice was greater repeated iceberg rafting events over the past 50 ka are shown by marine cores while the derivative inference of numerous corresponding glacial advances is supported by several clusters of 36 cl ages on glaciated surfaces and glacial boulders that are indicative of deglacial events between 40 and 12 ka these appear to be associated with heinrich events the earliest being inferred as heinrich 4 at about 40 ka during this advance the biis and scandinavian ice sheet sis were in contact and all of ireland was glaciated the ice sheet appears to have fluctuated several times between 40 and 25 ka although evidence for this is poorly preserved but the 36 cl and 14 c evidence is clear that the biis reached its lgm maximum size about 22 ka soon after heinrich event 2 when the biis and sis were not in contact one cluster of 36 cl and 14 c ages at 21 4 1 3 ka records an initial pulse of deglaciation that was followed by extensive deglaciation about 17 4 0 4 ka just before heinrich event 1 when the ice sheet readvanced contrary to previous views the biis probably existed throughout much of devensian time as a mobile and sensitive ice sheet during which the lgm advance was but one important event in places glacial deposits of the earlier devensian glaciation have previously been incorrectly identified as products of the later lgm glaciation

speleothem master chronologies combined holocene 18o and 13c records from the north island of new zealand and their palaeoenvironmental interpretation the stable isotope records of four stalagmites dated by 19 tims uranium series ages are combined to produce master chronologies for delta 18 o and delta 13 c the delta 18 o records display good overall coherence but considerable variation in detail variability in the delta 13 c records is greater but general trends can still be discerned this implies that too fine an interpretation of the structure of individual isotopic records can be unreliable speleothem delta 18 o values are demonstrated to show a positive relationship with temperature by comparing trends with other proxy records but also to respond negatively to rainfall amount speleothem delta 13 c is considered to be most influenced by rainfall the postglacial thermal optimum occur red around 10 8 ka bp which is similar in timing to antarctica but up to 2000 years earlier than most northern hemisphere sites increasingly negative delta 18 o values after 7 5 ka bp indicate that temperatures declined to a late mid holocene minimum centred around 3 ka bp but more positive values followed to mark a warm peak about 750 years ago which coincided with the mediaeval warm period of europe low 5110 values at 325 years bp suggest cooling coincident with the little ice age a marked feature of the delta 13 c record is an asymmetric periodicity averaging c 2250 years and amplitude of c 1 9parts per thousand it is concluded that this is mainly driven by waterbalance variations with negative swings representing particularly wet intervals the 5110 record shows a higher frequency cyclicity with a period of c 500 years and an amplitude of c 0 25 parts per thousand this is most likely to be temperature driven but some swings may have been amplified by precipitation

evidence for global teleconnections in a late pleistocene speleothem record of water balance and vegetation change at sudwala cave south africa abstract understanding the global response to millennial scale climatic events is essential to our comprehension of climatic teleconnections and projection of future change however the extent and nature of their expression in areas of the southern hemisphere is often viewed as equivocal here we report uranium thorium dating of speleothem formations sampled at sudwala cave in the north eastern lowveld region of south africa s summer rainfall zone srz the growth intervals of multiple formations alongside a detailed chronology and multi proxy analysis of two periods of growth 40 35 ka and 13 8 12 8 ka in a stalagmite sc1 provide information regarding key fluctuations in the palaeoclimatic and palaeoenvironmental conditions during the late pleistocene high resolution stable isotope trace element and micro raman analysis are used alongside petrographic investigation to provide a detailed assessment of the climatic conditions associated with the onset and termination of growth in sc1 the combined raman and petrographic analysis represents a rare approach enabling the identification of aragonite calcite shifts both within and across growth intervals and diagenetic events potentially significantly influencing the recorded signal and often resulting in the major loss of chemical information consequently the identification of this post depositional chemical alteration could become a crucial prerequisite in speleothem palaeoclimatology particularly in areas prone to aragonite speleothem deposition susceptible to calcite conversion such as cave sites hosted by dolomitic karst systems the multiple proxies used in this study highlight the complex forcing relationships between climatically related environmental change and local cave conditions on speleothem precipitation contesting a common paradigm by associating drier conditions at sudwala with the initiation of speleothem growth the growth interval identified in stalagmite sc1 during the late deglaciation 13 85 12 79 ka coincides convincingly with both the southern hemispherically forced antarctic cold reversal 14 1 12 8 ka and the younger dryas 12 9 11 5 ka of northern hemispheric origin identifying southern africa as a vital location for the investigation of the hemispheric to global expression of the millennial scale fluctuations of the last deglaciation

evidence against a significant younger dryas cooling event in new zealand pollen records of deglacial sequences from northwest nelson new zealand demonstrate that there was no significant temperature decline associated with the younger dryas in new zealand records of glacial advances at this time were either the product of increased snow accumulation under enhanced precipitation regimes or random variation rather than the result of a regional thermal decline this finding supports those models of younger dryas initiation that require neither enhanced westerly circulation nor significant thermal decline in the southern hemisphere

lateglacial landscape and vegetation change and the younger dryas climatic oscillation in new zealand abstract lateglacial sequences in new zealand show progressive afforestation and landscape stabilization reflecting a warming climate between 14 500 bp and 11 500 bp afforestation and landscape stability was achieved throughout most of the north island and the northwest sector of the south island in the south island scrub and tree ferns were replacing previous grasslands in the east by 11 000 bp and broadleaved forest was spreading in the west no significant reversals of these trends occurred and afforestation was complete by 9500 bp glaciers of the high central part of the southern alps made a series of advances between 14 000 and 9000 bp most of these advances are poorly dated but two moraines are of younger dryas age glacial advances in the face of the general lateglacial warming trend may have been driven by stronger westerly winds increasing snowfall on high altitude neves and by reduced ablation as a consequence of moist cloudy low insolation summers the cause of the northern hemisphere younger dryas cooling is still uncertain and expected southern hemisphere responses may differ according to the mechanism proposed for the cooling poor chronological resolution and apparent conflict between the various types of evidence for climatic change make detection of an unambiguous younger dryas in new zealand problematical

timing and duration of the last interglacial inferred from high resolution u series chronology of stalagmite growth in southern hemisphere high precision th 230 u 238 ages for a stalagmite from newdegate cave in southern tasmania australia define a rare record of precipitation between 100 and 155 ka before the present the fastest stalagmite growth occurred between 129 2 1 6 and 122 1 2 0 ka similar to 61 5 mm ka coinciding with a time of prolific coral growth from western australia 128 122 ka this is the first high resolution continental record in the southern hemisphere that can be compared and correlated with the marine record such correlation shows that in southern australia the onset of full interglacial sea level and the initiation of highest precipitation on land were synchronous the stalagmite growth rate between 129 2 and 142 2 ka similar to 5 9 mm ka was lower than that between 142 2 and 154 5 ka similar to 18 7 mm ka implying drier conditions during the penultimate deglaciation despite rising temperature and sea level this asymmetrical precipitation pattern is caused by latitudinal movement of subtropical highs and an associated westerly circulation in response to a changing equator to pole temperature gradient both marine and continental records in australia strongly suggest that the insolation maximum between 126 and 128 ka at 65 degreesn was directly responsible for the maintenance of full last interglacial conditions although the triggers that initiated penultimate deglaciation at similar to 142 ka remain unsolved c 2001 elsevier science b v all rights reserved

the temperature of europe during the holocene reconstructed from pollen data we present the first area average time series reconstructions of warmest month coldest month and mean annual surface air temperatures across europe during the last 12 000 years these series are based on quantitative pollen climate reconstructions from over 500 pollen sites assimilated using an innovative four dimensional gridding procedure this approach combines three dimensional spatial gridding with a fourth dimension represented by time allowing data from irregular time series to be focussed onto a regular time step we provide six regional reconstructed temperature time series as well as summary time series for the whole of europe the results suggest major spatial and seasonal differences in holocene temperature trends within a remarkably balanced regional and annual energy budget the traditional mid holocene thermal maximum is observed only over northern europe and principally during the summer this warming was balanced by a mid holocene cooling over southern europe whilst central europe occupied an intermediary position changes in annual mean temperatures for europe as a whole suggest an almost linear increase in thermal budget up to 7800 bp followed by stable conditions for the remainder of the holocene this early holocene warming and later equilibrium has been mainly modulated by increasing winter temperatures in the west which have continued to rise at a progressively decreasing rate up to the present day

speleothem u series dating of semi synchronous climate oscillations during the last deglaciation evidence for nearly synchronous climate oscillations during the last deglaciation has been found throughout the northern hemisphere but few records are based on independent time scales of calendar years we present a rare uranium series dated oxygen carbon isotope record for a speleothem from tangshan cave china which demonstrates that abrupt deglacial climatic oscillations from 16 800 to 10 500 yr bp are semi synchronous with those found in greenland ice core records relatively rapid shifts in speleothem oxygen isotope ratios demonstrate that the intensity of the east asian monsoon switched in parallel with the abrupt transitions separating the bolling allerod younger dryas and pre boreal climatic reversals however the dated isotopic transitions appear to have lasted longer our results demonstrate the dominant role of atmospheric teleconnections in the rapid propagation of deglacial climatic signals on a hemispheric scale and highlight the importance of u series dated speleothems in the timing and characterization of abrupt climate change c 2003 elsevier b v all rights reserved

holocene climate variability in antarctica based on 11 ice core isotopic records a comparison is made of the holocene records obtained from water isotope measurements along 11 ice cores from coastal and central sites in east antarctica vostok dome b plateau remote komsomolskaia dome c taylor dome dominion range d47 km105 and law dome and west antarctica byrd with temporal resolution from 20 to 50 yr the long term trends possibly reflect local ice sheet elevation fluctuations superimposed on common climatic fluctuations all the records confirm the widespread antarctic early holocene optimum between 11 500 and 9000 yr in the ross sea sector a secondary optimum is identified between 7000 and 5000 yr whereas all eastern antarctic sites show a late optimum between 6000 and 3000 yr superimposed on the long time trend all the records exhibit 9 aperiodic millennial scale oscillations climatic optima show a reduced pacing between warm events typically 800 yr whereas cooler periods are associated with less frequent warm events pacing 1200 yr

holocene glacier variations in new zealand a review abstract in the central southern alps of new zealand ice surface lowering has exposed extensive sections of lateral moraines allowing investigation of moraine stratigraphy and genesis the presence of multiple superposed palaeosurfaces within moraine sequences allows recognition of any disturbances displacements or contamination of till layers and interbedded organic material radiocarbon dating of buried wood and soils allows comparison between the holocene glacial history of the eastern ranges and that of the westland region the periodicity of glacier response has been similar to both areas although the precise timing of events has differed due to local climatic and environmental factors in general glaciers in new zealand expanded about 5000 4500 4200 3700 3500 3000 2700 2200 1800 1700 1500 1100 900 700 600 and 400 100 bp

the last glacial interglacial transition lgit in south westland new zealand paleoecological insight into mid latitude southern hemisphere climate change abstract high resolution pollen stratigraphy from three peat cores located within 20 km of lateglacial moraines in south westland new zealand provide detailed records of climate change during the last glacial interglacial transition lgit the pollen record shows the replacement of grassland by shrubland prior to ca 15 300 14 c yr bp 18 300 cal yr bp followed by the progressive development of broadleaf shrubland and scattered forest prior to ca 12 000 14 c yr bp 14 400 cal yr bp local vegetation changes around the time of the younger dryas chronozone 11 10 ka 14 c bp are evident but are not necessarily a result of regional climate cooling vegetation changes between ca 12 000 and 10 000 14 c yr bp 14 400 and 11 400 cal yr bp indicate a period of increased precipitation tall podocarp forest similar to that of the contemporary forest was well established by ca 10 000 14 c yr bp 11 400 cal yr bp a period of increased westerly circulation over southern new zealand is considered to be the most likely mechanism for causing the increased precipitation between ca 12 000 and 10 000 14 c yr bp 14 300 and 11 400 cal yr bp increased precipitation would also provide a mechanism for initiating lgit ice advance in the area data from these records show some support for global climate change models that propose inter hemispheric linkage but may be more supportive of a climate change model that incorporates an increased westerly circulation over southern new zealand during the lgit