variations in the discharge and organic matter content of stalagmite drip waters in lower cave bristol six drip waters which were actively depositing stalagmites in lower cave bristol were analysed both for discharge and luminescence properties drip discharges were determined for two different years and show a complex response to surface precipitation variations inter annual variability in drip discharge is demonstrated to be significantly higher than intra annual variability and discharge was demonstrated both to increase and decrease non linearly with increased precipitation drip waters demonstrate a correlation between their luminescence intensity and drip discharge with increased luminescence in winter as more organic matter is flushed through the aquifer the strength of the relationship between luminescence intensity and discharge increases with increased discharge the results presented here have implications for the palaeoenvironmental interpretation of annual growth laminae and the growth rates of stalagmite samples 1997 john wiley sons ltd

bristlecone pine tree rings and volcanic eruptions over the last 5000 yr many years of low growth identified in a western usa regional chronology of upper forest border bristlecone pine pinus longaeva and pinus aristata over the last 5000 yr coincide with known large explosive volcanic eruptions and or ice core signals of past eruptions over the last millennium the agreement between the tree ring data and volcano ice core data is high years of ring width minima can be matched with known volcanic eruptions or ice core volcanic signals in 86 of cases in previous millennia while there is substantial concurrence the agreement decreases with increasing antiquity many of the bristlecone pine ring width minima occurred at the same time as ring width minima in high latitude trees from northwestern siberia and or northern finland over the past 4000 5000 yr suggesting climatically effective events of at least hemispheric scale in contrast with the ice core records the agreement between widely separated tree ring records does not decrease with increasing antiquity these data suggest specific intervals when the climate system was or was not particularly sensitive enough to volcanic forcing to affect the trees and they augment the ice core record in a number of ways by providing confirmation from an alternative proxy record for volcanic signals by suggesting alternative dates for eruptions and by adding to the list of years when volcanic events of global significance were likely including the mid 2nd millennium bc eruption of thera

july temperature during the second millennium reconstructed from idaho tree rings an 858 year proxy record of july temperature for east central idaho shows multi decadal periods of extreme cooling centered around ad 1300 1340 1460 and after ad 1600 these cold intervals are interrupted by prolonged warm spells in the early 1400s late 1500s and in the 1930s the spatial signature of the paleoclimate record is centered on the north central rockies and central great plains and expands over north america following a wave like pattern neither instrumental nor proxy data in idaho northeast valleys show unusual warming during the twentieth century climate episodes over the last three centuries are in broad agreement with the greenland borehole temperature history low frequency patterns are consistent with other northern hemisphere tree ring records for the late holocene and provide a chronology of warm and cold intervals during the little ice age

corroborated rainfall records from aragonitic stalagmites abstract sr and ba levels of two proximal aragonite speleothems from cold air cave south africa are examined at m resolution a compositional map derived from parallel secondary ion mass spectrometry linescans indicates heterogeneity perpendicular to the stalagmite growth axis precluding the use of single linescans as a climatic proxy technique a 40 yr averaged trace element record for the cave produced from multiple parallel linescans on both stalagmites is compared with regional and local climatic rainfall temperature data for 1955 1996 this period includes two extensive drought episodes there is poor correlation between trace elements and annual mean temperature droughts correspond to minima in trace element ratios and peaks correspond to annual maxima in rainfall the onset and termination of droughts are notable inflexions however in detail annual rainfall magnitude does not correlate directly with trace element ratios indicating that kinetic factors notably variations in speleothem growth rate play a key role in trace element uptake by aragonite averaged long data sets constrained by chronological control have potential in the study of sub decadal precipitation patterns

annual climate variability in the holocene interpreting the message of ancient trees abstract over vast areas of the world s landmasses where climate beats out a strong seasonal rhythm tree growth keeps unerring time in their rings trees record many climate melodies played in different places and different eras recent years have seen a consolidation and expansion of tree ring sample collections across the traditional research areas of north america and europe and the start of major developments in many new areas of eurasia south america and australasia from such collections are produced networks of precisely dated chronologies records of various aspects of tree growth registered continuously year by year across many centuries their sensitivities to different climate parameters are now translated into ever more detailed histories of temperature and moisture variability across expanding dimensions of time and space with their extensive coverage high temporal resolution and rigid dating control dendroclimatic reconstructions contribute significantly to our knowledge of late holocene climates most importantly on timescales ranging from 1 to 100 years in special areas of the world where trees live for thousands of years or where subfossil remnants of long dead specimens are preserved work building chronologies covering many millennia continues apace very recently trees have provided important new information about major modes of general circulation dynamics linked to the el nino southern oscillation and the north atlantic oscillation and about the effect of large volcanic eruptions as for assessing the significance of 20th century global warming the evidence from dendroclimatology in general supports the notion that the last 100 years have been unusually warm at least within a context of the last two millennia however this evidence should not be considered equivocal the activities of humans may well be impacting on the natural growth of trees in different ways making the task of isolating a clear climate message subtly difficult

reconstruction of annual temperature 1590 1979 for longmire washington derived from tree rings abstract annual growth records from trees at timberline in the cascade range of washington are correlated with variations in temperature and snow depth and used to reconstruct climatic variation in the past response surfaces indicate that growth of mountain hemlock tsuga mertensiana and subalpine larch larix lyallii is positively correlated with summer july to september temperature and negatively correlated with spring march snow depth when snow depth is at or below average during years of above average snow depth temperature has little effect on mountain hemlock but has a negative effect on growth in subalpine larch these interactions make it difficult to reconstruct these climatic variables separately using standard methods mean annual temperature values which combine information on both summer temperature and spring snow depth were estimated from a regression model that reconstructs past temperature at longmire washington as a function of larch and hemlock tree ring chronologies the reconstruction of mean annual temperature shows temperatures between 1590 and 1900 to be approximately 1 c lower than those of the 20th century only during a short period from 1650 to 1690 did temperatures approach 20th century values

measurements of the cretaceous paleolatitude of vancouver island consistent with the baja british columbia hypothesis a previously unsampled outcrop of gently dipping or flat lying upper cretaceous sedimentary strata in the vancouver island region which contains unaltered aragonitic mollusk fossils yielded a stable remanent magnetization that is biostratigraphically consistent with cretaceous magnetochrons 33r 33n and 32r these results characterized by shallow inclinations indicate an upper cretaceous paleolatitude of about 25 3 degrees north which is equivalent to that of modern day baja california these findings are consistent with the baja british columbia hypothesis which puts the insular superterrane well south of the oregon california border in the late cretaceous

seasonal variations in sr mg and p in modern speleothems grotta di ernesto italy sub annual variations in trace element chemistry and luminescence have recently been demonstrated from speleothems and offer the potential of high resolution palaeoclimatic proxies however no studies have yet examined microscopic trace element variations in relation to modern cave conditions in this study the spatial variations in trace element sr mg and p concentrations in speleothems a stalagmite and a soda straw stalactite from the alpine ernesto cave temperature 6 6 0 1 c in a forested catchment in ne italy have been studied using secondary ion mass spectrometry sims and compared with environmental parameters and waters in the modern cave an annual lamination exists in the stalagmite and soda straw stalactite in the form of clear calcite with narrow visible layers which are uv fluorescent and interpreted to contain soil derived humic fulvic acids washed into the cave during autumn rains microanalyses were undertaken of seven annual laminae probably deposited during the 1960s in the stalagmite and seven laminae in the 1990s for the stalactite the analysis results show that sr consistently has a trough and p a peak centred on the inclusion rich layer mg shows mainly a negative covariation with sr in laminae formed in the 1990s but a positive covariation in the stalagmite formed in 1960s the spatial scale of the main geochemical variations is the same as that of annual laminae of inclusion poor and inclusion rich couplets mass balance arguments are used to show that the p is inorganic in form and presumably occurs as individual phosphate ions within the calcite most drip waters show limited chemical variations but a summer peak in trace elements in 1995 and a decrease in mg ca in the following winter are notable more pronounced covariations in mg ca and sr ca are shown by a site with highly variable drip rates where ratios increase at slow drip rates the strongest seasonal variations are found in pool waters where ratios increase reflecting significant ca removal from the water into the calcite during the winter in response to seasonal pco2 variations in cave air thus the cave waters compositions tend to reflect climate conditions such that mg ca and sr ca are tentatively interpreted to be higher when climate conditions are dry combining results from the speleothems and cave water along with the behaviour of each trace species mg ca variations in the speleothems are considered to reflect their variation in the cave waters whereas sr incorporation is also dependent on precipitation rate in this case mainly controlled by temporal variations in pco2 in the cave and conceivably also by inhibitors such as phosphate p adsorption a fraction of which is subsequently incorporated within calcite depends on aqueous phosphate concentration and water flux both of which should increase during the autumn therefore multiple trace element profiles in speleothems reflect multiple aspects of environment seasonality and conditions and hence a calibration against weather records is desirable to establish their palaeoclimatological meaning the strong annual variation of trace elements and particularly p can provide chronological markers for high resolution studies of other climate proxies such as stable isotopes

trace element variations in coeval holocene speleothems from gb cave southwest england we report trace element mg sr and ba records based on laser ablation inductively coupled plasma mass spectrometry la icp ms from three coeval holocene speleothems from great chamber in gb cave southwest england the trace element records are placed on a common timescale on the basis of a suite of tims 230th 234u ages this permits assessment of the reproducibility of the trace element record in coeval speleothems the trace element records are not coherent raising dobuts over the reliability of individual trace element records as potential archives of palaeoenvironmental information mg sr in speleothem calcite has been proposed as a potential palaeothermometer as mg partitioning into calcite from water is temperaturedependent while sr partitioning into calcite is temperature independent however we present the results of calculations which demonstrate that the observed mg sr values in the three stalagmites cannot have been produced by holocene temperature changes alone and that other processes m

drought reconstructions for the continental united states abstract the development of a 2 lat 3 long grid of summer drought reconstructions for the continental united states estimated from a dense network of annual tree ring chronologies is described the drought metric used is the palmer drought severity index pdsi the number of grid points is 154 and the reconstructions cover the common period 1700 1978 in producing this grid an automated gridpoint regression method called point by point regression was developed and tested in so doing a near optimal global solution was found for its implementation the reconstructions have been thoroughly tested for validity using pdsi data not used in regression modeling in general most of the gridpoint estimates of drought pass the verification tests used in addition the spatial features of drought in the united states have been faithfully recorded in the reconstructions even though the method of reconstruction is not explicitly spatial in its design the drought reconstructions show that the 1930s dust bow

holocene climate variability in europe evidence from δ18o textural and extension rate variations in three speleothems time series o isotope profiles for three u th dated stalagmites have revealed that for much of the holocene a site on the atlantic seaboard sw ireland exhibits first order 18o trends that are almost exactly out of phase with coupled 18o curves from two southern european sites se france and nw italy in the irish stalagmite cc3 from crag cave sw ireland low 18o at 10 000 cal yr bp reflects cool conditions by the early to mid holocene 9000 6000 cal yr bp 18o had increased reflecting the onset of warmer conditions on the atlantic seaboard this shift to higher 18o was accompanied by a marked increase in the stalagmite extension rate reinforcing our interpretation that this was a period of relative warmth except for an episode of increased extension rate about 5500 yr ago 18o in the crag stalagmite exhibits a gradual decrease accompanied by declining extension rates between 7800 and 3500 cal yr bp interpreted as a cooling trend there is evidence for increases in both 18o and stalagmite extension rate in the period from 3500 cal yr bp to the present day suggesting a return to warmer conditions on the atlantic seaboard in the stalagmite from nw italy er76 grotta di ernesto trentino province the early holocene c 9200 7800 cal yr bp is characterised by high 18o probably indicative of warm and or dry conditions exceptionally low 18o from 7800 to 6900 cal yr bp at this site reflects a well defined wet phase cerin wet phase in the last three millennia this stalagmite exhibits a shift to lower 18o interpreted as some combination of cooler and or wetter conditions unlike the irish stalagmite the italian sample does not show a correlation between 18o and extension rate instead its extension rate correlates roughly with 13c presumably reflecting a climate driven vegetation change in the early holocene 18o in the french stalagmite cl26 grotte de clamouse herault province se france was low relative to its holocene average for much of the period since c 3500 cal yr bp this stalagmite exhibits higher 18o than in the early holocene suggesting warmer conditions like the irish stalagmite the french sample exhibits a well defined correlation between 18o and extension rate had drip water availability been the dominant control on 18o at this semi arid site then higher 18o would have been accompanied by lower not higher extension rates this suggests strongly that temperature rather than rainfall amount was the dominant control at this site while conclusions regarding the patterns of climate variability on a continent scale must remain tentative because of the limited number of stalagmites studied we argue that early holocene warm conditions on the atlantic seaboard irish site coincided with relatively cool conditions at the clamouse site by c 3500 yr ago the pattern appears to have been reversed

a new genus and species of polychelid lobster crustacea decapoda eryonidae from the early jurassic hettangian of british columbia a single specimen of decapod crustacean preserved in ventral view and compressed represents a new genus and species of eryonid lobster wrangelleryon perates the discovery in lower jurassic hettangian sediments of the sandilands formation in british columbia represents the first occurrence of eryonidae in north america and reinforces a global distribution of the family in the jurassic the occurrence in british columbia on the wrangellia terrane supports the lower latitude setting in which the species lived resume un specimen unique de crustace decapode preserve en vue ventrale et comprime represente un nouveau genre et une nouvelle espece de homard eryonide wrangelleryon perates la decouverte dans des sediments du jurassique inferieur hettangien de la formation de sandilands en colombie britannique represente la premiere occurrence d un eryonide en amerique du nord et consolide la these d une repartition planetaire de cette famille au jurassique la presence du specimen en colombie britannique dans le terrane de wrangellie appuie la these voulant que l espece ait vecu abasse latitude traduit par la redaction

annual precipitation in the yellowstone national park region since ad 1173 cores and cross sections from 133 limber pine pinus flexilis james and douglas fir pseudotsuga menziesii mirbel franco at four sites were used to estimate annual july to june precipitation in the yellowstone national park region for the period from ad 1173 to 1998 examination of the long term record shows that the early 20th century was markedly wet compared to the previous 700 yr extreme wet and dry years within the instrumental period fall within the range of past variability and the magnitude of the worst case droughts of the 20th century ad 1930s and 1950s was likely equaled or exceeded on numerous occasions before ad 1900 spectral analysis showed significant decadal to multidecadal precipitation variability at times this lower frequency variability produces strong regime like behavior in regional precipitation with the potential for rapid high amplitude switching between predominately wet and predominately dry conditions over multiple time scales strong yellowstone region precipitation anomalies were almost always associated with spatially extensive events spanning various combinations of the central and southern u s rockies the northern u s southern canadian rockies and the pacific northwest 2007 university of washington all rights reserved

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

quaternary deposits and glacial stratigraphy in ireland quaternary stratigraphic studies in ireland have been based largely on lithostratigraphy the division of complex sedimentary sequences into the traditional framework of munsterian and midlandian events has created a series of stratigraphic scenarios which cannot be fully substantiated either by biostratigraphy or by facies basin analysis many of the current problems of glacial stratigraphy in ireland therefore arise directly from the field procedures used and the frameworks used to subdivide sedimentary sequences these problems are centred on the selection of type sites the subdivision of sedimentary sequences into unnatural divisions the concepts of direct and indirect stratigraphy classical models of climatically determined ice advance retreat cycles and the genetic inferences of the term till the conceptual basis of various stratigraphic schemes has changed little since the work of farrington 1934 1966 it is argued that a more realistic approach to description and assessment of glacigenic sediments should be based on basinal facies analysis and must include a documentation of the composition and geometry of three dimensional facies variations palaeoenvironmental interpretations of complex glacigenic sequences especially in coastal locations should take account of the influences of marine ice sheets on the sedimentary record in the past most sequences were interpreted in terms of glacioterrestrial models a large body of sedimentary evidence now indicates that shallow glaciomarine environments occurred along the margins of the last ice sheet during its maximum and subsequent retreat phases the locations and patterns of associated icemarginal systems indicate that the magnitude of and patterns of crustal deformation were greater and more complex than formerly realised thus the primary control on sea level variation at successive ice sheet margins was largely a function of glacioisostatic disequilibrium although complex glacial and glacially related sequences are known it is argued here that most of the multiple glacigenic sequences in ireland can be accommodated within the midlandian cold stage the basal units from certain sequences and erratic fans have been attributed to events earlier than the midlandian however it is difficult to compare these traces of earlier events from different sectors of the island due to poor dating correlation and the fact that direct and indirect stratigraphy is not adequately defined or separated the age of the gortian style interglacial sequences the implications of their floristic composition and their relationships to drift stratigraphy remains a major problem in stratigraphic constructions of the irish quaternary the stratigraphic significance of many till units must remain largely unknown until these matters are resolved at present it is not clear if the gortian sequences represent more than one interglacial a series of exposures in ulster provide evidence for major environmental changes during the midlandian cold stage these include an early stadial an early forest biozone 48 1 ka bp an early herb biozone 41 5 ka bp a middle interstadial phase of cold but non glacial aspect 30 5 ka bp a late stadial max 24 22 ka bp and a late glacial climatic oscillation the late midlandian stadial comprises a major glaciation that almost covered the island and a later more restricted phase when drumlins formed in the northern and western parts of the island max 17 ka bp

tree ring and summer temperature response to volcanic aerosol forcing at the northern tree line kola peninsula russia potential linkages between volcanic activity and a 403 year record of pinus sylvestris l scots pine growth and summer temperatures estimated from tree ring widths are evaluated from an arctic tree line site on the kola peninsula northwestern russia the joint occurrence of volcanic eruptions and severe negative ring width values is more than four times that expected by chance a composite average of temperatures indicates that a 0 72 c temperature reduction is typical for the year immediately following volcanic eruptions while tree growth is reduced for up to two decades the greenland ice sheet project 2 gisp2 volcanic sulphate record shows a small but significant correlation with summer temperatures volcanic aerosols originating at low and middle latitudes appear to cause the greatest ring width reduction and cooling

tree ring evidence for climatically effective volcanic eruptions abstract ringwidth variations from temperature sensitive upper timberline sites in the sierra nevada show a marked correspondence to the decadal pattern of volcanic sulfate aerosols recorded in a greenland ice core acidity profile and a significant negative growth response to individual explosive volcanic events the appearance of single events in the mid latitude tree ring record in connection with ice core evidence from the arctic and historical records from the mediterranean indicates that the majority of these events represent climatically effective volcanic eruptions producing temperature decreases on the order of 1 c for up to 2 yr after the initial eruption clusters of climatically effective volcanic events may serve as a trigger to glaciation and are consistently associated with lowered ringwidths and late holocene glacier advance in the sierra nevada the tree ring record strongly suggests forcing of solar radiation receipt and temperatures by increased volcanic aerosols especially during the recess peak advances and matthes little ice age advances from 1400 to 1850 a d intervals with an absence of significant volcanic aerosol production or historically documented eruptive activity correspond to intervals of significantly increased indexed ringwidth values minimal numbers of severe annual negative ringwidth anomalies and an absence of glacial deposits in the southern sierra nevada

spatial variability in cave drip water hydrochemistry implications for stalagmite paleoclimate records the identification of vadose zone hydrological pathways that most accurately transmit climate signals through karst aquifers to stalagmites is critical for accurately interpreting climate proxies contained within individual stalagmites a three year cave drip hydrochemical study across a spectrum of drip types in crag cave sw ireland reveals substantial variability in drip hydrochemical behaviour stalagmites fed by very slow drips 2 ml min sites apparently unconnected with local meteorological events water from these drips was typically undersaturated with respect to calcite and thus did not result in calcite deposition data presented here suggest that drips in this flow regime also experience flow re routing and blocking and that any stalagmites developed under such drips are unsuitable as mid to high resolution paleoclimate proxies most drip sites demonstrated seasonal ca2 and mg2 variability that was probably linked to water excess prior calcite precipitation along the flowpath affected the chemistry of slowly dripping sites while dilution predominantly controlled the water chemistry of the more rapidly dripping sites this research underscores the importance of understanding drip hydrology prior to selecting stalagmites for paleoclimate analysis and before interpreting any subsequent proxy data

capturing season specific precipitation signals in the northern rocky mountains usa using earlywood and latewood tree rings douglas fir pseudotsuga menziesii mirb franco total width earlywood and latewood tree ring chronologies were developed from six lower forest border sites in the northern rocky mountain region of central idaho and southwestern montana usa to assess the potential for season specific moisture reconstructions these long lived arid site trees share strong between tree and between site coherence and subannual tree ring chronologies reliably span the past seven centuries mapping spatiotemporal patterns in northern rocky mountain precipitation highlighted winter and summer dominated precipitation regimes that transition along a west to east gradient when douglas fir tree rings were compared with instrumental climate records season specific correlations emerged between earlywood and latewood total width earlywood and latewood shared the most statistically significant monthly correlations with april june precipitation whereas variability in adjusted latewood was tuned to june august precipitation principal component analysis indicated that the leading mode of common variance for earlywood and adjusted latewood explained 65 and 55 variance in the chronologies respectively pearson s correlations between earlywood principal component one and the northern rocky mountain precipitation field showed that annual july june and spring april june precipitation exhibited the strongest pattern of significance in central idaho and southwestern montana valleys and the snake river plain summer precipitation june august was correlated with adjusted latewood principal component one and was particularly pronounced along and east of the continental divide in southwestern montana these results indicate that douglas fir earlywood and adjusted latewood tree rings in the northern rocky mountains retain season specific precipitation signals and may be helpful for studying historical precipitation within the winter summer transition zone

a middle jurassic to early tertiary andean sierran arc model for the coast belt of british columbia regional tectonic features of the western canadian cordillera can be interpreted in terms of middle jurassic accretion of a single composite superterrane stikinia wrangellia alexander to ancestral north america closure of the intervening cache creek bridge river ocean moved the continental edge to a new position west of the accreted superterrane the coast belt is primarily a succession of superimposed middle jurassic to early tertiary magmatic arcs related to prolonged subduction of pacific ocean lithosphere beneath the new north american margin discrete magmatic pulses separated by lulls or periods of relative quiescence successively overprinted the new margin the insular and intermontane superterranes previously viewed as widely separate entities prior to mid cretaceous time were already amalgamated before an initial middle jurassic overprint produced an ancestral coast belt late jurassic to early cretaceous rift related marine basins mid to late cretaceous compressional structures and early tertiary extensional features coincident with the coast belt are subsidiary intraplate attributes that reflect external adjustments in plate motions within a primary subduction related andean magmatic arc

comparison of high resolution sub annual records of trace elements in a modern 1911 1992 speleothem with instrumental climate data from southwest australia high spatial resolution measurements of mg p u sr ba and na using 193 nm excimer laser ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern australia the age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew 1911 1992 this chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content eleven laser ablation transects across a 0 5 mm wide section of the speleothem growth axis were measured cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record p and u positively and mg inversely mimic the sudden 20 decrease in annual rainfall experienced by this region since 1965 we argue that p from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil owing to the low p retention capacity of southwest australian soils both vegetation activity and the transport of vegetation derived hpo42 are sensitive to rainfall groundwater p concentration may also influence the transport of u through the strong affinity between phosphate and uranyl ions mg appears to be sensitive to groundwater residence time as this affects drip water mg ca composition by preferential loss of ca during drier episodes when calcite precipitates before reaching the stalagmite the effects of groundwater residence time may also be important for sr on inter annual scales however the behaviour of sr on the annual cycle is opposite to mg but compatible with ba and na which are shown to depend on speleothem growth rate

mg sr and sr isotope geochemistry of a belgian holocene speleothem implications for paleoclimate reconstructions in this study variations in mg ca sr ca and 87sr 86sr ratios in a holocene belgian speleothem cave secondary carbonate deposit are interpreted in terms of changes in water residence time and changes in weathering processes possibly induced by changes in west european climate a stalagmite from the pere noel cave belgium was dated with the tims u th method and was deposited between 13 and 2 ka bp the 1000 mg ca ratio varies between 4 9 and 26 and displays short term changes but no significant long term trend the 1000 sr ca ratio varies between 0 09 and 0 31 and displays both short term changes and a long term decreasing trend from 12 9 to 3 5 ka in parallel the sr isotopic composition of the speleothem decreases from 0 7090 at 12 9 ka to 0 7088 at 3 5 ka the sr isotope ratio is higher than expected from the overlying limestone 87sr 86sr 0 7081 which implies an external source of radiogenic sr most probably from a silicate phase short term and long term changes in mg ca sr ca as well as long term changes of 87sr 86sr ratios can be explained by changes in the dissolution and precipitation processes of the host limestone these processes are controlled by changes in water residence times linked to changes in the water excess precipitation minus evapo transpiration c 2000 elsevier science b v all rights reserved

low frequency temperature variations from a northern tree ring density network we describe new reconstructions of northern extratropical summer temperatures for nine subcontinental scale regions and a composite series representing quasi northern hemisphere temperature change over the last 600 years these series are based on tree ring density data that have been processed using a novel statistical technique age band decomposition designed to preserve greater long timescale variability than in previous analyses we provide time dependent and timescale dependent uncertainty estimates for all of the reconstructions the new regional estimates are generally cooler in almost all precalibration periods compared to estimates obtained using earlier processing methods particularly during the 17th century one exception is the reconstruction for northern siberia where 15th century summers are now estimated to be warmer than those observed in the 20th century in producing a new northern hemisphere series we demonstrate the sensitivity of the results to the methodology used once the number of regions with data and the reliability of each regional series begins to decrease we compare our new hemisphere series to other published large regional temperature histories most of which lie within the 1 confidence band of our estimates over most of the last 600 years the 20th century is clearly shown by all of the palaeoseries composites to be the warmest during this period

structure of the 8200 year cold event revealed by a speleothem trace element record abrupt first order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western ireland during the 8200 year event the major cooling episode 8200 years before the present are interpreted as responses to a drier climate lasting about 37 years both shifts are centered on 8330 80 years before the present coinciding with a large oxygen isotope anomaly and a change in the calcite petrography in this very high resolution monthly record antipathetic second order oscillations in phosphorus and strontium reveal decreased growth rates and increased rainfall seasonality growth rate variations within the event reveal a two pronged structure consistent with recent model simulations

non linearities in drip water hydrology an example from stump cross caverns yorkshire drip rate data have been collected at 15 min intervals at six locations in stump cross caverns n england since 1998 the different drip sites cover a wide range of drip rates from 2 drips s to 2 drips h and in general the variability of drip rate increases with mean drip rate in our continuous data sampling we observe rapid discharge increases which appear to be synchronous between drips sites and which can be explained by flow switching of the water overlying the cave during times of high infiltration rate such as intense rain storms or rapid snowmelt a test for non linearity white test in the drip series provides very strong evidence that many of the drip sequences are non linear we conclude that at our drip sites there is a non linear input weather and non linearities within the karst system leading to non linear dripping which is independent of drip rate our results have implications for stalagmite palaeoclimatology where such widespread non linearities have not been taken account of

secular temperature trends for the southern rocky mountains over the last five centuries 1 pre instrumental surface temperature variability in the southwestern united states has traditionally been reconstructed using variations in the annual ring widths of high altitude trees that live near a growth limiting isotherm a number of studies have suggested that the response of some trees to temperature variations is non stationary warranting the development of alternative approaches towards reconstructing past regional temperature variability here we present a five century temperature reconstruction for a highaltitude site in the rocky mountains derived from the oxygen isotopic composition of cellulose d 18 oc from bristlecone pine trees the record is independent of the co located growth based reconstruction while providing the same temporal resolution and absolute age constraints the empirical correlation between d 18 oc and instrumental temperatures is used to produce a temperature transfer function a forward model for cellulose isotope variations driven by meteorological data and output from an isotope enabled general circulation model is used to evaluate the processes that propagate the temperature signal to the proxy the cellulose record documents persistent multidecadal variations in d 18 oc that are attributable to temperature shifts on the order of 1c but no sustained monotonic rise in temperature or a step like increase since the late 19th century the isotope based temperature history is consistent with both regional wood density based temperature estimates and some sparse early instrumental records citation berkelhammer m and l d stott 2012 secular temperature trends for the southern rocky mountains over the last five centuries geophys res lett 39 l17701 doi 10 1029 2012gl052447

on the long term context for late twentieth century warming 1 previous tree ring based northern hemisphere temperature reconstructions portray a varying amplitude range between the medieval warm period mwp little ice age lia and present we describe a new reconstruction developed using largely different methodologies and additional new data compared to previous efforts unlike earlier studies we quantify differences between more traditional std and regional curve standardization rcs methodologies concluding that rcs is superior for retention of low frequency trends continental north american versus eurasian rcs series developed prior to merging to the hemispheric scale cohere surprisingly well suggesting common forcing although there are notable deviations e g fifteenth to sixteenth century results indicate clear mwp warm lia cool and recent warm episodes direct interpretation of the rcs reconstruction suggests that mwp temperatures were nearly 0 7c cooler than in the late twentieth century with an amplitude difference of 1 14c from the coldest 1600 1609 to warmest 1937 1946 decades however we advise caution with this analysis although we conclude as found elsewhere that recent warming has been substantial relative to natural fluctuations of the past millennium we also note that owing to the spatially heterogeneous nature of the mwp and its different timing within different regions present palaeoclimatic methodologies will likely flatten out estimates for this period relative to twentieth century warming which expresses a more homogenous global fingerprint therefore we stress that presently available paleoclimatic reconstructions are inadequate for making specific inferences at hemispheric scales about mwp warmth relative to the present anthropogenic period and that such comparisons can only still be made at the local regional scale

century scale solar variability and alaskan temperature change over the past millennium 1 correlation of geologic histories from 130 alaskan glaciers with a record of solar variation suggests that multi decadal to century scale temperature variations in the north pacific and arctic sectors have been influenced by solar forcing over the past thousand years mountain glacier fluctuations are primarily a record of summer cooling and the composite glacial history from three climatic regions across alaska shows ice expansions approximately every 200 years compatible with a solar mode of variability the modulating effects of the cold phases of the pacific decadal oscillation and the arctic oscillation may when in phase with decreased solar activity serve to amplify cooling forcing glacier advance

summer temperatures in the canadian rockies during the last millennium a revised record we present a significant update to a millennial summer temperature reconstruction 1073 1983 that was originally published in 1997 utilising new tree ring data predominantly picea engelmannii the reconstruction is not only better replicated but has been extended 950 1994 and is now more regionally representative calibration and verification statistics were improved with the new model explaining 53 of may august maximum temperature variation compared to the original 39 of april august mean temperatures the maximum latewood density data which are weighted more strongly in the regression model than ringwidth were processed using regional curve standardisation to capture potential centennial to millennial scale variability the reconstruction shows warm intervals comparable to twentieth century values for the first half of the eleventh century the late 1300s and early 1400s the bulk of the record however is below the 1901 1980 normals with prolonged cool periods from 1200 to 1350 and from 1450 to the late 19th century the most extreme cool period is observed to be in the 1690s these reconstructed cool periods compare well with known regional records of glacier advances between 1150 and the 1300s possibly in the early 1500s early 1700s and 1800s evidence is also presented of the influence of solar activity and volcanic events on summer temperature in the canadian rockies over the last 1 000 years although this reconstruction is regional in scope it compares well at multi decadal to centennial scales with northern hemisphere temperature proxies and at millennial scales with reconstructions that were also processed to capture longer timescale variability this coherence suggests that this series is globally important for the assessment of natural temperature variability over the last 1 000 years

a new species of lobster astacidea erymidae from the smithers formation middle jurassic of british columbia canada a single carapace and its counterpart of an erymoid lobster collected from the middle jurassic smithers formation in british columbia permits description of a new species eryma walkerae the specimen represents only the fourth species of eryma described from north america and documents a north polar route of dispersal for erymids into north america

centennial scale holocene climate variability revealed by a high resolution speleothem δ18o record from sw ireland evaluating the significance of holocene submillennial 18 o variability in the greenland ice cores is crucial for understanding how natural climate oscillations may modulate future anthropogenic warming a high resolution oxygen isotope record from a speleothem in southwestern ireland provides evidence for centennial scale 18 o variations that correlate with subtle 18 o changes in the greenland ice cores indicating regionally coherent variability in the early holocene evidence for previously undetected early holocene cooling events is presented but mid to late holocene ice rafting in the north atlantic appears to have had little impact on 18 o at this ocean margin site

biomass effects on stalagmite growth and isotope ratios a 20th century analogue from wiltshire england increases in calcite deposition rates combined with decreases in 13c and 18o in three modern stalagmites from brown s folly mine wiltshire england are correlative with a well documented re vegetation above the mine increased soil pco2 resulted in greater amounts of dissolved caco3 in the drip waters which consequently increased annual calcite deposition rates the absence of deposition prior to 1916 28 years after the mine was closed indicates that vegetation had not yet sufficiently developed to allow higher pco2 values to form in the soil lower 13c values through time may reflect the increased input of isotopically light biogenic carbon to the total dissolved inorganic carbon dic 18o decreased synchronously with 13c reflecting the increased importance of isotopically light winter recharge due to greater biomass induced summer evapotranspiration this is the first empirical demonstration that vegetation density can control stalagmite growth rates 13c and 18o contributing critical insights into the interpretation of these climate proxies in ancient stalagmites

marine triassic faunas of north america their significance for assessing plate and terrane movements the distribution of marine triassic invertebrate faunas in north america is reviewed to recognize forms that may have paleolatitudinal significance

the little ice age in the canadian rockies abstract this paper reviews the evidence and history of glacier fluctuations during the little ice age lia in the canadian rockies episodes of synchronous glacier advance occurred in the 12th 13th early 18th and throughout the 19th centuries regional ice cover was probably greatest in the mid 19th century although in places the early 18th century advance was more extensive glaciers have lost over 25 of their area in the 20th century selective preservation of the glacier record furnishes an incomplete chronology of events through the 14th 17th centuries in contrast varve sequences provide continuous annually resolved records of sediments for at least the last millennium in some highly glacierized catchments such records have been used to infer glacier fluctuations evaluation of recent proxy climate reconstructions derived from tree rings provides independent evidence of climate fluctuations over the last millennium most regional glacier advances follow periods of reduced summer temperatures reconstructed from tree rings particularly ca 1190 1250 1280 1340 1690s and the 1800s reconstructed periods of higher precipitation at banff alberta since 1500 are 1515 1550 1585 1610 1660 1680 and the 1880s glacier advances in the early 1700s the late 1800s and in places the 1950 1970s reflect both increased precipitation and reduced summer temperatures negative glacier mass balances from 1976 to 1995 were caused by decreased winter balances the glacier fluctuation record does not contain a simple climate signal it is a complex response to several interacting factors that operate at different timescales evaluation of climate proxies over the last millennium indicates continuous variability at several superimposed timescales dominated by decade century patterns only the 19th century shows a long interval of sustained cold summers this suggests that simplistic concepts of climate over this period should be abandoned and replaced with more realistic records based on continuous proxy data series the use of the term lia should be restricted to describing a period of extended glacier cover rather than being used to define a period with specific climate conditions

annual to sub annual resolution of multiple trace element trends in speleothems this study aims to establish evidence for the widespread existence of preserved high resolution trace element variations in speleothems that may have climatic significance ion microprobe analysis of speleothems reveals that annual to sub annual variations in element chemistry exist at five shallow western european cave sites crag cave county kerry and ballynamintra county waterford ireland uamh an tartair sutherland scotland grotte pere noel belgium grotta di ernesto ne italy with widely varying climatic geomorphic and geological settings the variations are not restricted to species mg sr and ba known to substitute directly for ca in the calcite lattice but include h f na and p phosphorus as phosphate displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element the technique allows estimation of growth rate of speleothems at any interval of interest which is one of several possible uses in palaeoclimatology

reconstructed summer temperature in the northern rocky mountains wilderness usa ring widths from whitebark pine pinus albicaulis englem and subalpine larch larix lyallii parl collected at three high elevation sites were used to develop tree growth chronologies to reconstruct summer temperature anomalies a step wise multiple regression procedure was used to screen potential predictor variables to generate a transfer function capable of skillfully reconstructing summer temperature the resulting regression model explained approximately 38 of the adjusted variance in the instrumental temperature record the fidelity of the reconstruction was verified using product mean and sign tests both of which suggested significant predictive power in the reconstructions p 0 05 reduction of error re and coefficient of efficiency ce measures were both positive indicating the reconstruction contained useful climate information cool periods often coincided with reduced solar activity and or periods of increased volcanic activity differences between this reconstruction and others encompassing a broader geographic scale highlight the importance of developing local reconstructions of climate variability particularly when used in conjunction with ecological data sets that describe the occurrence of fires or insect epidemics mixed and divergent climate response relationships were evident in the whitebark pine chronologies and suggest subalpine larch may be a more useful species than whitebark pine to target for the development of temperature reconstructions in this region

the 2002 2003 el nino recorded in australian cave drip waters implications for reconstructing rainfall histories using stalagmites 1 a 30 month study of drip hydrochemistry from kooringa cave eastern australia revealed a clear geochemical response to the 2002 2003 el nino through the drought drip discharge fell to base flow drip ca2 concentrations fell by half and drip mg ca and sr ca increased in a co varying pattern calcite mg ca and sr ca predicted from drip waters displayed a marked increase through and just beyond the period of greatest moisture deficit the results suggest that stalagmites from shallow caves in drought sensitive eastern australia potentially preserve a valuable record of el nino la nina history