late glacial to holocene volcanism of jom bolok valley east sayan mountains siberia recorded by microtephra layers of the lake kaskadnoe 1 sediments abstract this article presents first tephrochronological data on the volcanic activity in the valley of the jom bolok river east sayan mountains siberia which is the largest manifestation of the holocene eruptions in central asia the data results from our study of the proglacial kaskadnoe 1 lake situated near the jom bolok basalt field the lake sediments include a series of tephra rich layers radiocarbon dating of the lake sediments provided a robust age model which allowed us to build timing of eruptions formed the jom bolok volcanic field we recognize two large phases of volcanism separated by almost 5 thousand years dormant phase the first phase is traced back to ca 14 3 cal ka bp and lasted until 6 3 cal ka bp ten clusters of microtephra layers in the sediments of the first phase show 300 800 years recurrence of the volcanic events weakening upward the event of 14 3 13 3 cal ka bp probably represents the strongest eruptions of the jom bolok the second phase started ca 1 6 cal ka bp and highly likely continues in our days its strongest eruptions occurred between 1 6 and 0 8 cal ka bp with periodicity of 200 years this tephrostratigraphy shows a multiplicity of the jom bolok volcanic events and amplifies the earlier built scheme resulted from investigations of the stratified basalts pyroclasts and lake damming events additionally we indicate a possible influence of the jom bolok volcanic activity on the regional and global climatic changes

dendrochronology and radiocarbon dating of subfossil conifer logs from a peat bog maramures mts romania abstract fifty six subfossil samples dominantly norway spruce picea abies l karst have been collected between 2010 and 2014 from a peat bog located on the vinderel plateau farc u massif maramures mountains romania seven floating chronologies have been developed the longest floating chronology contains 259 years while the shortest one spans 56 years the oldest and youngest ages obtained from six of the radiocarbon dated samples are 1717 19 14 c bp 255 388 cal ad and 1039 16 14 c bp 985 1023 cal ad respectively the floating chronologies provide incomplete coverage of the c 200 to 1326 ad period these floating chronologies supported with 14 c dates provide a crucial step towards the production of an eastern carpathians composite coniferous chronology the lack of trunk accumulation after the early 14th century suggests the disappearance of trees from the proximity of the site it closely follows the sharp increase of grazing indicator pollens in the region around the late 13th century conjunctly this evidence points to a substantial landscape land use change from forest to pasture during the 13th century which probably indicates the beginning of the typical traditional vertical transhumance which became a characteristic livestock management in the maramures region over the past centuries

multiple stable isotopes from oak trees in southwestern scotland and the potential for stable isotope dendroclimatology in maritime climatic regions across much of europe eurasia and n america there exist networks of long tree ring chronologies which under favourable circumstances may be used to provide a record of palaeoclimate information a proportion of these tree ring archives primarily those collected for archaeological dating purposes represent a significant and largely untapped palaeoenvironmental archive such records may be unsuitable for palaeoclimatic reconstruction based solely upon their physical characteristics ring width and density owing to weak or poorly expressed climatic forcing this is especially true of oak chronologies from maritime regions this study explores the potential for extracting a climate signal from such chronologies by comparing the stable isotope ratios of c h and o from the rings of common oak quercus robur trees in southwestern scotland with local and regional meteorological data summer growing season climate influences all three isotopes and the relationships identified are consistent with published empirical and mechanistic studies the climate signal appears strongest in o and weakest in h the c and o series in combination explain 31 of the variance in july august mean temperature measured locally and 26 when compared with a homogenised gridded dataset for the period ad1957 2002 over longer timescales the combination of c and o isotopes may also preserve a significant low frequency signal july august r 2 0 57 9 year running mean ad1879 1998 these findings demonstrate the potential of stable isotope dendroclimatology for investigating climatic change from oak chronologies in maritime regions 2008 published by elsevier b v

carbon isotope excursions and the oxidant budget of the ediacaran atmosphere and ocean a possible global drop in marine carbon isotope values to as low as 12 peedee belemnite pdb recorded in the ediacaran shuram formation of oman has been attributed to the non steady state oxidation of oceanic dissolved organic carbon doc resulting from the rise in atmospheric oxygen to near modern values at the end of the precambrian geologic constraints indicate that the excursion lasted between 25 and 50 m y requiring a doc pool thousands of times to 10 000 times the modern inventory to conform with carbon isotope mass balance calculations for a 12 excursion at the consequent rates of doc oxidation oceanic sulfate and oxygen in the atmosphere and oceans are exhausted on a time scale of 800 k y oxidant depletion is incompatible with independent geochemical and biological indicators that show oceanic sulfate and oxygen levels were maintained or increased during the shuram excursion furthermore a doc driven excursion does not explain strong covariation between the carbon and oxygen isotope record these indicators show that negative isotope excursions recorded in the shuram and other ediacaran sections are unlikely to represent a global ocean signal

new ice core evidence for a volcanic cause of the a d 536 dust veil in new zealand human cryptosporidiosis demonstrates spring and autumn peaks of incidence with the spring peak being three times greater in magnitude than the autumn peak the imbalance between the two peaks is notable and may be associated with the high livestock density in new zealand in the summer and autumn the cryptosporidiosis rate was positively associated with temperatures in the current and previous month highlighting the importance of outdoor recreation to transmission no associations between spring incidence and weather were found providing little support for the importance of drinking water pathways imported travel cases do not appear to be an important factor in the aetiology of cryptosporidiosis in new zealand

summer temperatures in eastern taimyr inferred from a 2427 year late holocene tree ring chronology and earlier floating series a brief review is presented of the progress to date in constructing a long continuous ring width chronology from living and subfossil siberian larch larix gmelinii in the eastern part of the taimyr peninsula a near 2500 year chronology running up to the present has been assembled and several shorter earlier series have been produced that are dated approximately on the basis of radiocarbon dates a description is given of the production of separate early summer and annual mean temperature histories based on the recent chronology spanning more than 2000 years these two reconstructions are based on alternative methods of statistical processing of the measured tree ring data the early summer and annual reconstructions agree well in the long term components of their variability providing evidence for anomalous warmth in the third tenth to twelfth and twentieth centuries and a prolonged cool period throughout the sixteenth and seventeenth and in the early nineteenth centuries the mean growth and other statistical parameters of the earlier chronologies also suggest that conditions for tree growth were very favourable in the earlier holocene particularly in the fourth millen nium bc this is strongly indicative of an early holocene climatic optimum in taimyr at that time other material in hand and earlier published radiocarbon dates demonstrate the feasibility of constructing continuous ring width chronologies and temperature estimates extending throughout all of the last 8000 years

high latitude eurasian paleoenvironments introduction and synthesis abstract this special issue developed partly from the open pages conference held in moscow in may 2002 the dominant theme of the present collection of articles is the late pleistocene and holocene paleoenvironmental history of northern eurasia from the white to the black sea and from the estonia to the kurile islands here we briefly summarize the available paleorecords from the fsu territory covering the last 1500 years a number of records allow one to distinguish the climatic pattern of the 9th 13th centuries from earlier and later colder conditions in the kola peninsula urals taymir russian plain caucasus and east siberia the 10th 12th centuries were also slightly warmer in the far east kurile islands the warming of the 14th century in several regions including the russian plain altai and central asia was at least as intense as the earlier one at ca 1 kyr before present or even warmer the available data for this time period remain controversial in the arid area of central asia records from the caspian sea area suggest moderate temperature and relatively high humidity in the first half of the millenium whereas in the tien shan mountains the beginning of the millenium seems to have been warm and dry various line of evidence suggest a climatic deterioration in the second half of the last millenium throughout the fsu including the european part siberia the caucasus the mountains of the central asia the far east and the arctic archipelagoes

tornetrask tree ring width and density ad 500 2004 a test of climatic sensitivity and a new 1500 year reconstruction of north fennoscandian summers this paper presents updated tree ring width trw and maximum density mxd from tornetrask in northern sweden now covering the period ad 500 2004 by including data from relatively young trees for the most recent period a previously noted decline in recent mxd is eliminated non climatological growth trends in the data are removed using regional curve standardization rcs thus producing trw and mxd chronologies with preserved low frequency variability the chronologies are calibrated using local and regional instrumental climate records a bootstrapped response function analysis using regional climate data shows that tree growth is forced by april august temperatures and that the regression weights for mxd are much stronger than for trw the robustness of the reconstruction equation is verified by independent temperature data and shows that 63 64 of the instrumental inter annual variation is captured by the tree ring data this is a significant improvement compared to previously published reconstructions based on tree ring data from tornetrask a divergence phenomenon around ad 1800 expressed as an increase in trw that is not paralleled by temperature and mxd is most likely an effect of major changes in the density of the pine population at this northern tree line site the bias introduced by this trw phenomenon is assessed by producing a summer temperature reconstruction based on mxd exclusively the new data show generally higher temperature estimates than previous reconstructions based on tornetrask tree ring data the late twentieth century however is not exceptionally warm in the new record on decadal to centennial timescales periods around ad 750 1000 1400 and 1750 were equally warm or warmer the 200 year long warm period centered on ad 1000 was significantly warmer than the late twentieth century p 0 05 and is supported by other local and regional paleoclimate data the new tree ring evidence from tornetrask suggests that this medieval warm period in northern fennoscandia was much warmer than previously recognized

50 myr recovery from the largest negative δ13c excursion in the ediacaran ocean sedimentary rocks deposited during the ediacaran period 630 542 ma contain carbonates whose carbon isotopic ratios show a marked negative excursion consisting of a precipitous drop from 5 to 12 followed by a sub linear recovery to positive 13c values isotopic ages u pb and thermal subsidence modelling are combined to constrain the excursion in time and indicate an onset at 600 ma and duration of recovery of approximately 50 myr the excursion is widely recognized in oman and has potential correlatives in ediacaran strata elsewhere and may thus represent a characteristic feature of the ediacaran period the amplitude of this carbon isotope excursion far exceeds those of other neoproterozoic anomalies the isotopic trend of negative excursion and long term recovery spanned at least one short lived glacial episode at 580 ma but appears unrelated to glaciation which indicates that negative anomalies in the neoproterozoic marine carbon isotope record are not directly or uniquely linked to ice ages

fennoscandian summers from ad 500 temperature changes on short and long timescales quantitative estimates of 1480 years of summer temperatures in northern fennoscandia have previously been derived from continuous treering records from northern sweden here we show the results of spectral analyses of these data only a few peaks in the spectra are consistently significant when the data are analyzed over a number of sub periods relatively timestable peaks are apparent at periods of 2 1 2 5 3 1 3 6 4 8 32 33 and for a range between 55 100 years these results offer no strong evidence for solar related forcing of summer temperatures in these regions our previously published reconstruction was limited in its ability to represent long timescale temperature change because of the method used to standardize the original tree ring data here we employ an alternative standardization technique which enables us to capture temperature change on longer timescales considerable variance is now reconstructed on timescales of several centuries in comparison with modern normals 1951 70 generally extended periods when cool conditions prevailed prior to the start of the instrumental record include 500 700 790 870 1110 1150 1190 1360 1570 1750 a d with the most significant cold troughs centred on about 660 800 1140 1580 1620 and 1640 predominantly warm conditions occurred in 720 790 870 1110 and 1360 1570 with peaks of warmth around 750 930 990 1060 1090 1160 1410 1430 1760 and 1820

reassessing the evidence for tree growth and inferred temperature change during the common era in yamalia northwest siberia the development of research into the history of tree growth and inferred summer temperature changes in yamalia spanning the last 2000 years is reviewed one focus is the evolving production of tree ring width trw and tree ring maximum latewood density mxd larch larix sibirica chronologies incorporating different applications of regional curve standardisation rcs another focus is the comparison of independent data representing past tree growth in adjacent yamalia areas yamal and polar urals and the examination of the evidence for common growth behaviour at different timescales the sample data we use are far more numerous and cover a longer time span at yamal compared to the polar urals but yamal has only trw while there are both trw and mxd for the polar urals we use more data sub fossil and from living trees than in previous dendroclimatic studies in this region we develop a new trw chronology for yamal more than 2000 years long and running up to 2005 for the polar urals we develop new trw and mxd chronologies that show good agreement at short 15 years and medium 15e100 years timescales demonstrating the validity of attempts to reconcile the evidence of longer timescale information that they provide we use a conservative application of the rcs approach two curve signal free rcs guarding against the possibility of modern sample bias a possible inflation of recent chronology values arising out of inadvertent selection of mostly relatively fast growing trees in recent centuries we also transform tree indices to have a normal distribution to remove the positive chronology skew often apparent in rcs trw chronologies this also reduces the apparent magnitude of 20th century tree growth levels thereis generallygoodagreement between all chronologies as regardsthe major featuresof the decadal to centennial variability low tree growth periods for which the inferred summer temperatures are approximately 2 5 c below the 1961e90 reference are apparent in the 15 year smoothed reconstructions

a 9111 year long conifer tree ring chronology for the european alps a base for environmental and climatic investigations an ultra long tree ring width chronology 9111 years long 7109 bc to ad 2002 has been established based on the analysis and dating of 1432 subfossil dry dead wood samples and cores from 335 living trees the material was collected from treeline or near treeline sites c 2000 to 2400 m a s l mainly in the eastern alps the availability of preserved samples through time at high altitudinal sites is influenced by alpine forest history and is partly climatically controlled as shown by comparisons of the sample depth record of the eastern alpine conifer chronology eacc with the holocene glacier record the similarity of variations over time between the sample depth of the chronology and the mid holocene gisp2 10be record suggest a relationship between sample depth and solar activity the eastern alpine conifer chronology has already been used as a dating base in environmental studies eg on glacier fluctuations as well as in archaeological studies

twentieth century trends in tree ring stable isotopes δ13c and δ18o of larix sibirica under dry conditions in the forest steppe in siberia 1 tree ring width density and ratio of stable isotopes 13c 12c and 18o 16o in wood and cellulose were determined for larch larix sibirica ledeb growing under water deficit conditions in the forest steppe zone in central siberia 54 24 n 89 57 e for the period 1850 2005 dendroclimatic analysis of the chronologies indicated precipitation to be the most important factor determining indicated parameters precipitation of june is significantly correlated with tree ring width and maximum density r 0 36 and 0 43 p 0 05 respectively relations of 13c and 18o to precipitation are similar but the most important month is july r 0 47 p 0 05 for 13c r 0 29 p 0 05 for 18o further 18o is positively related to the mean temperatures of july r 0 30 p 0 05 carbon and oxygen isotope ratios in wood and cellulose showed strong negative trends for the last 100 years the reason for this decrease could be the observed shift of the beginning of the vegetation period to earlier dates up to 1 week in spring and the increased use of precipitation water stored in the soil from october of the previous year although other explanations cannot be excluded in particular the physiological effect of increasing atmospheric co2 also responsible for lower 13c values thus an earlier start of the vegetation period could lead to tree ring formation during a period with higher water availability resulting in stronger isotopic fractionation and 13c depletion also reflected in a higher earlywood to latewood ratio at the same time highly 18o depleted water from october precipitation of the previous year is absorbed the incorporation of this isotopically lighter water during photosynthesis is reflected in the wood and cellulose of tree rings

timing of the cataclastic deformation along the akaishi tectonic line central japan this paper describes k ar ages of cataclasites and fault gouges from the akaishi tectonic line atl central japan petrological and mineralogical features of these rocks are also examined based on the results we test the hypothesis that the k ar ages of these rocks represent the age of hydrothermal alteration associated with the fault movement intensity of deformation and alteration increase passing from host rock into cataclasite and finally into fault gouge this increase corresponds to an increase of the value of crystallinity index kubler index of the micaceous minerals contained in these rocks furthermore the degree of rejuvention of k ar ages of the micaceous minerals increases in the same sense a correlation of k ar ages plotted on the y axis versus kubler index plotted on the x axis yields a concave curve asymptotically parallel with the x axis at approximately 15 ma this curve is interpreted to represent the mode of decrease of the relative amounts of inherited argon in the k ar system of the micaceous minerals corresponding to an increase in the intensity of deformation and alteration inclination of the curve becomes zero if all the inherited argon is lost from the k ar system of the micaceous minerals thus it is concluded that the hydrothermal alteration occurred at approximately 15 ma the strike slip basin along the atl formed the middle miocene the k ar dating of atl gouges indicates that the atl was active simultaneously with formation of the strike slip basin along its trace during the middle miocene

high resolution palaeoclimatology of the last millennium a review of current status and future prospects this review of late holocene palaeoclimatology represents the results from a pages clivar intersection panel meeting that took place in june 2006 the review is in three parts the principal high resolution proxy disciplines trees corals ice cores and documentary evidence emphasizing current issues in their use for climate reconstruction the various approaches that have been adopted to combine multiple climate proxy records to provide estimates of past annual to decadal timescale northern hemisphere surface temperatures and other climate variables such as large scale circulation indices and the forcing histories used in climate model simulations of the past millennium we discuss the need to develop a framework through which current and new approaches to interpreting these proxy data may be rigorously assessed using pseudo proxies derived from climate model runs where the answer is known the article concludes with a list of recommendations first more raw proxy data are required from the diverse disciplines and from more locations as well as replication for all proxy sources of the basic raw measurements to improve absolute dating and to better distinguish the proxy climate signal from noise second more effort is required to improve the understanding of what individual proxies respond to supported by more site measurements and process studies these activities should also be mindful of the correlation structure of instrumental data indicating which adjacent proxy records ought to be in agreement and which not third large scale climate reconstructions should be attempted using a wide variety of techniques emphasizing those for which quantified errors can be estimated at specified timescales fourth a greater use of climate model simulations is needed to guide the choice of reconstruction techniques the pseudo proxy concept and possibly help determine where given limited resources future sampling should be concentrated

late holocene environmental change in arctic western siberia the putorana plateau western siberia situated on the boundary of the atlantic and continental siberian climate provinces is sensitive to shifts in atmospheric circulation three lakes on an altitudinal transect were studied using chironomid subfossils to provide the first estimates of late holocene climate in this remote poorly studied region of arctic russia the analysis of sediment cores from three closely located lakes is rare in palaeoenvironmental studies and enables the role of other environmental variables which may be a potential source of error in palaeoclimatic reconstructions to be assessed the chironomid based reconstructions suggest a more maritime climate c 3400 cal bp with july temperatures c 1 5 c warmer than present which cooled rapidly by c 2 c with a more continental climate between 3200 and 2600 cal bp these trends are similar in timing and scale to other northern hemisphere records the recent chironomid records from all three lakes show pronounced faunal changes over the last 50 years probably directly or indirectly because of climate driven changes in catchment hydrology this is particularly evident in the recent record from an open lake within a large wetland habitat which appears relatively insensitive to changes in july air temperatures

is the 20th century warming unprecedented in the siberian north abstract to answer the question has the recent warming no analogues in the siberian north we analyzed larch tree samples larix gmelinii rupr from permafrost zone in the eastern taimyr tay 72 n 102 e using tree ring and stable isotope analyses for the climatic optimum period cop 4111 3806 bc and medieval warm period mwp 917 1150 ad in comparison to the recent period rp 1791 2008 ad we developed a description of the climatic and environmental changes in the eastern taimyr using tree ring width and stable isotope 13 c 18 o data based on statistical verification of the relationships to climatic parameters temperature and precipitation additionally we compared our new tree ring and stable isotope data sets with earlier published july temperature and precipitation reconstructions inferred from pollen data of the lama lake taimyr peninsula 18 o ice core data from akademii nauk ice cap on severnaya zemlya sz and 18 o ice core data from greenland gisp2 as well as tree ring width and stable carbon and oxygen isotope data from northeastern yakutia yak we found that the cop in tay was warmer and drier compared to the mwp but rather similar to the rp our results indicate that the mwp in tay started earlier and was wetter than in yak july precipitation reconstructions obtained from pollen data of the lama lake oxygen isotope data from sz and our carbon isotopes in tree cellulose agree well and indicate wetter climate conditions during the mwp consistent large scale patterns were reflected in significant links between oxygen isotope data in tree cellulose from tay and yak and oxygen isotope data from sz and gisp2 during the mwp and the rp finally we showed that the recent warming is not unprecedented in the siberian north similar climate conditions were recorded by tree rings stable isotopes pollen and ice core data 6000 years ago

multispectral analysis of northern hemisphere temperature records over the last five millennia aiming to describe spatio temporal climate variability on decadal to centennial time scales and longer we analyzed a data set of 26 proxy records extending back 1 000 5 000 years all records chosen were calibrated to yield temperatures the seven irregularly sampled series in the data set were interpolated to a regular grid by optimized methods and then two advanced spectral methods namely singular spectrum analysis ssa and the continuous wavelet transform were applied to individual series to separate significant oscillations from the high noise background this univariate analysis identified several common periods across many of the 26 proxy records a millennial trend as well as oscillations of about 100 and 200 years and a broad peak in the 40 70 year band to study common nh oscillations we then applied multichannel ssa temperature variations on time scales longer than 600 years appear in our analysis as a dominant trend component which shows climate features consistent with the medieval warm period and the little ice age statistically significant nh wide peaks appear at 330 250 and 110 years as well as in a broad 50 80 year band strong variability centers in several bands are located around the north atlantic basin and are in phase opposition between greenland and western europe

temperature and precipitation history of the arctic as the planet cooled from peak warmth in the early cenozoic extensive northern hemisphere ice sheets developed by 2 6 ma ago leading to changes in the circulation of both the atmosphere and oceans from not vert similar2 6 to not vert similar1 0 ma ago ice sheets came and went about every 41 ka in pace with cycles in the tilt of earth s axis but for the past 700 ka glacial cycles have been longer lasting not vert similar100 ka separated by brief warm interglaciations when sea level and ice volumes were close to present the cause of the shift from 41 ka to 100 ka glacial cycles is still debated during the penultimate interglaciation not vert similar130 to not vert similar120 ka ago solar energy in summer in the arctic was greater than at any time subsequently as a consequence arctic summers were not vert similar5 c warmer than at present and almost all glaciers melted completely except for the greenland ice sheet and even it was reduced in size substantially from its present extent with the loss of land ice sea level was about 5 m higher than present with the extra melt coming from both greenland and antarctica as well as small glaciers the last glacial maximum lgm peaked not vert similar21 ka ago when mean annual temperatures over parts of the arctic were as much as 20 c lower than at present ice recession was well underway 16 ka ago and most of the northern hemisphere ice sheets had melted by 6 ka ago solar energy reached a summer maximum 9 higher than at present not vert similar11 ka ago and has been decreasing since then primarily in response to the precession of the equinoxes the extra energy elevated early holocene summer temperatures throughout the arctic 1 3 c above 20th century averages enough to completely melt many small glaciers throughout the arctic although the greenland ice sheet was only slightly smaller than at present early holocene summer sea ice limits were substantially smaller than their 20th century average and the flow of atlantic water into the arctic ocean was substantially greater as summer solar energy decreased in the second half of the holocene glaciers re established or advanced sea ice expanded and the flow of warm atlantic water into the arctic ocean diminished late holocene cooling reached its nadir during the little ice age about 1250 1850 ad when sun blocking volcanic eruptions and perhaps other causes added to the orbital cooling allowing most arctic glaciers to reach their maximum holocene extent during the warming of the past century glaciers have receded throughout the arctic terrestrial ecosystems have advanced northward and perennial arctic ocean sea ice has diminished here we review the proxies that allow reconstruction of quaternary climates and the feedbacks that amplify climate change across the arctic we provide an overview of the evolution of climate from the hot house of the early cenozoic through its transition to the ice house of the quaternary with special emphasis on the anomalous warmth of the middle pliocene early quaternary warm times the mid pleistocene transition warm interglaciations of marine isotope stages 11 5e and 1 the stage 3 interstadial and the peak cold of the last glacial maximum

a pollen climate transfer function from the tundra and taiga vegetation in arctic siberia and its applicability to a holocene record abstract this study aims to establish evaluate and apply a modern pollen climate transfer function from the transition zone between arctic tundra and light needled taiga in arctic siberia lacustrine samples n 96 from the northern siberian lowlands of yakutia were collected along four north to south transects crossing the arctic forest line samples span a broad temperature and precipitation gradient mean july temperature t july 7 5 18 7 c mean annual precipitation p ann 114 315 mm yr redundancy analyses are used to examine the relationship between the modern pollen signal and corresponding vegetation types and climate performance of transfer functions for t july and p ann were cross validated and tested for spatial autocorrelation effects the root mean square errors of prediction are 1 67 c for t july and 40 mm yr for p ann a climate reconstruction based on fossil pollen spectra from a siberian arctic lake sediment core spanning the holocene yielded cold conditions for the late glacial 1 2 c below present t july warm and moist conditions were reconstructed for the early to mid holocene 2 c higher t july than present and climate conditions similar to modern ones were reconstructed for the last 4000 years in conclusion our modern pollen data set fills the gap of existing regional calibration sets with regard to the underrepresented siberian tundra taiga transition zone the holocene climate reconstruction indicates that the temperature deviation from modern values was only moderate despite the assumed arctic sensitivity to present climate change

conservation of soil organic matter through cryoturbation in arctic soils in siberia 1 cryoturbation mixing of soil layers due to repeated freeze thaw processes is a major soil forming process in arctic regions which may contribute to long term storage of c in soils of northern latitudes our goal was to determine the effect of subduction of organic matter by cryoturbation on microbial decomposition processes in tundra soils buried layers were situated at 30 60 cm depth between bg and b horizons but exhibited a c and n content highly similar to present day a horizons radiocarbon dating revealed however that the mean age of c in the buried layer was three times higher 1300 years bp than in the a horizon 400 years bp suggesting that decomposition rates in the buried layer were delayed the observed microbial processes support this result gross c and n mineralization rates were substantially lower in the buried layers than in the respective a horizons the amount of c stored in the buried layer still doubles the amount of c stored in topsoil horizons o and a assuming that the buried layer originates from both o and a horizons this indicates that o and a horizon at time of burying 800 1300 years bp must have been significantly thicker and present day o and a horizon at this site may still have the capacity to accumulate additional c cryoturbation therefore may lead to additional long term storage of carbon in the system by 1 retarding decomposition processes of buried organic material and 2 enabling the soil to restart c accumulation in topsoil layers

a multi proxy approach for revealing recent climatic changes in the russian altai for the first time we present a multi proxy data set for the russian altai consisting of siberian larch tree ring width trw latewood density mxd 13c and 18o in cellulose chronologies obtained for the period 1779 2007 and cell wall thickness cwt for 1900 2008 all of these parameters agree well between each other in the high frequency variability while the low frequency climate information shows systematic differences the correlation analysis with temperature and precipitation data from the closest weather station and gridded data revealed that annual trw mxd cwt and 13c data contain a strong summer temperature signal while 18o in cellulose represents a mixed summer and winter temperature and precipitation signal the temperature and precipitation reconstructions from the belukha ice core and teletskoe lake sediments were used to investigate the correspondence of different independent proxies low frequency patterns in trw and 13c chronologies are consistent with temperature reconstructions from nearby belukha ice core and teletskoe lake sediments showing a pronounced warming trend in the last century their combination could be used for the regional temperature reconstruction the long term 18o trend agrees with the precipitation reconstruction from the teletskoe lake sediment indicating more humid conditions during the twentieth century therefore these two proxies could be combined for the precipitation reconstruction

reconstruction of the extratropical nh mean temperature over the last millennium with a method that preserves low frequency variability abstracta new multiproxy reconstruction of the northern hemisphere extratropical mean temperature over the last millennium is presented the reconstruction is performed with a novel method designed to avoid the underestimation of low frequency variability that has been a general problem for regression based reconstruction methods the disadvantage of this method is an exaggerated high frequency variability the reconstruction is based on a set of 40 proxies of annual to decadal resolution that have been shown to relate to the local temperature the new reconstruction shows a very cold little ice age centered around the 17th century with a cold extremum for 50 yr smoothing of about 1 1 k below the temperature of the calibration period ad 1880 1960 this cooling is about twice as large as corresponding numbers reported by most other reconstructions in the beginning of the millennium the new reconstruction shows small anomalies in agreement with previous studies however the new temperature reconstructi

solar and volcanic fingerprints in tree ring chronologies over the past 2000 years abstract the sun is the main driver of earth s climate yet the sun s role in forcing decadal to centennial climate variations has remained controversial especially in the context of understanding contributions of natural climate forcings to continuing global warming to properly address long term fingerprints of solar forcing on climate long term very high resolution globally distributed climate proxy records are necessary in this study we compile and evaluate a near global collection of annually resolved tree ring based climate proxies spanning the past two millennia we statistically assess these records in both the time and frequency domains for solar forcing i e total solar irradiance tsi and climate variability with emphasis on centennial time scales analyses in the frequency domain indicate significant periodicities in the 208 year frequency band corresponding to the devries cycle of solar activity additionally results from superposed epoch analysis sea point toward a possible solar contribution in the temperature and precipitation series however solar climate associations remain weak with for example no clear linkage distinguishable in the southwestern united states drought records at centennial time scales other forcing factors namely volcanic activity appear to mask the solar signal in space and time to investigate this hypothesis we attempted to extract volcanic signals from the temperature proxies using a statistical modelling approach wavelet analysis of the volcanic contribution reveals significant periodicities near the devries frequency during the little ice age lia this remarkable and coincidental superposition of the signals makes it very difficult to separate volcanic and solar forcing during the lia nevertheless the volcano free temperature records show significant periodicities near the devries periodicity during the entire past 1500 years further pointing to solar mechanisms and emphasising the need for solar related studies in the absence of strong multi decadal volcanic forcing

reconciling pollen stratigraphical and tree ring evidence for high and low frequency temperature variability in the past millennium abstract climate change and variability assessments require an understanding of their long term and period low frequency and short term and period high frequency variations pollen data have conventionally been thought of as a proxy of low frequency variation of past climates but of more limited applicability for studying high frequencies likewise tree rings are commonly supposed to reflect faithfully high frequency variations with additional uncertainties attributable to variations at lower frequencies here we challenge this view in the context of pollen and tree ring based temperature reconstructions from high latitude europe the two types of records are compared and it is shown that the pollen and tree ring based reconstructions exhibit similar temperature variability on centennial and longer scales these can be revealed using timescale dependent filtering the same method surmounts geochronological discrepancies thus enabling reconciliation of the proxies resulting new reconstructions validate over the instrumental period over longer intervals our new proxy fusions cover the climatic reversals of the medieval climate anomaly during the 10th to 13th centuries little ice age during the 14th to 19th centuries and 20th century warming the warmest spells occurred in association with the medieval climate anomaly and during the 20th century the coolest intervals occurred in relation to little ice age conditions the new reconstructions show that decadal temperature amplitude has been approximately 2 5 c in the past and thus considerably larger than inferred from spatially large scale estimates of temperature anomalies

interpreting carbon isotope excursions carbonates and organic matter abstract variations in the carbon isotopic compositions of marine carbonate and organic carbon provide a record of changes in the fraction of organic carbon buried through time and may provide clues to changes in rates of weathering and sources of organic carbon paired carbonate and organic carbon isotope determinations provide a possibility of interpreting not only changes in the global carbon cycle through time but changes in atmospheric pco2 as well interpretations of these types of data are typically rather qualitative a quantitative basis is required to develop a better understanding of changes in the carbon cycle for this purpose we employ a simple model of the global carbon cycle which is subjected to a number of different perturbations each lasting 500 ky i e much longer than the residence times of carbon and phosphorus in the ocean atmosphere system in addition to standard considerations of carbon mass and isotopic fluxes to the ocean atmosphere system from weathering and volcanism and fluxes of organic carbon and carbonate carbon to sediments the model incorporates sensitivity of the photosynthetic carbon isotope effect to changes in pco2 the inclusion of this parameter leads to unexpected carbon isotope responses to forcing that causes increased rates of organic carbon burial a series of simple to more complex simulations illustrates the significant effects of varying differences between the carbon isotopic composition of sedimented carbonate and organic carbon b with constant b a 50 increase in organic carbon burial produces a parallel increase in carbonate and organic carbon isotopic compositions however the same simulation with b responsive to pco2 changes produces an initial parallel 13 c increase but this is followed by an even greater 13 c enrichment in organic carbon because pco2 falls in response to increased organic carbon burial the counterintuitive overall result of the enhanced organic carbon burial event is that the carbonate carbon isotopic composition actually decreases because of the more substantial increase in 13 c org in addition we illustrate the effects on carbon isotopic compositions of the oceanic inorganic carbon reservoir and buried organic matter of a 50 increase in volcanic co2 outgassing a 50 increase in weathering rate with coupled phosphate and riverine carbon flux responses a 50 decrease in shale associated organic carbon weathering a 50 decrease in silicate weathering rate and the possible effects of the rise in abundance of c4 plants in the late miocene to recent we compare the model simulated carbon isotopic responses for some of these experiments to paired carbonate and organic carbon records to illustrate how these records might be interpreted in light of the model response