low frequency summer temperature variation in central sweden since the tenth century inferred from tree rings living and subfossil scots pine pinus sylvestris l sampled close to the present tree line in the central scandinavian mountains were used to build a continuous 1091 year long tree ring width chronology spanning from ad 909 to 1998 summer temperatures of the growth year had the highest influence on annual growth the hackren chronology represent a record of summer temperatures where periods of low growth and poor regeneration of pine represent unfavourable climate conditions low growth was encountered in the mid twelfth thirteenth late sixteenth early seventeenth and late eighteenth centuries periods of high growth high regeneration rate and above average growth indicating high summer temperatures were recognized in the mid tenth to late eleventh mid fourteenth mid seventeenth and twentieth centuries as the chronology is well correlated with other high latitude proxy data from fennoscandia as well as the northern hemisphere we argue that the hackren chronology is a valid proxy data reco

the influence of climate on 13c 12c and 18o 16o ratios in tree ring cellulose of pinus sylvestris l growing in the central scandinavian mountains the stable isotope composition of tree rings is known to contain valuable information of past climatic and environmental changes which may be used as a complement to tree ring width and maximum latewood density in climate reconstructions in this study we examine the character and strength of the climate signal captured in the delta o 18 and delta c 13 values of scots pine pinus sylvestris l trees growing at the tree line in the central scandinavian mountains between 4 and 14 trees were pooled to produce annual records of carbon and oxygen isotope ratios from tree ring cellulose spanning the period ad 1736 2006 weather conditions of the current growing season most strongly influenced the carbon and oxygen isotope ratios in a given tree ring both records showed positive correlations with temperature sunshine and air pressure and negative associations with precipitation the overall climate signal in delta c 13 appeared to be slightly stronger than that of delta o 18 spatial correlation analysis with gridded instrumental data demonstrated that the carbon series captured the summer temperature signal in a broad region of mid west sweden and the eastern part of norway greatly exceeding the spatial coverage of the signal derived from pine ring widths growing in the central scandinavian mountains a weak relationship between delta c 13 and precipitation and a much stronger temperature and sunshine dependence may imply that photosynthetic rate rather than stomatal conductance is more important in controlling the inter annual tree ring delta c 13 variability in the area moreover it was shown that the climate delta o 18 and delta c 13 relationship was temporally unstable throughout the twentieth century which was linked to large scale shifts in climate that may have altered the isotope climate dependence our results thus demonstrate that stable isotopes in tree rings from maritime high altitude scandinavia can provide high resolution regional climate information especially regarding parameters associated with temperature the non stationary nature of the isotope precipitation relationship may provide important information on past changes in the large scale atmospheric circulation during summer however these issues needs to be further investigated before pine tree ring isotopes from this region can be confidently used in palaeoclimate reconstructions c 2011 elsevier b v all rights reserved less

past summer temperatures inferred from dendrochronological records of fitzroya cupressoides on the eastern slope of the northern patagonian andes

climatologic and hydrologic influences on the oxygen isotope ratio of tree cellulose in coastal southern california during the late 20th century 1 the oxygen isotope ratio 18o of precipitation in continental midlatitude regions is a complex measure of atmospheric dynamics and regional climate variability and can be preserved in geologic archives however continuous modern observations of precipitation 18o in many midlatitude regions particularly in the coastal western united states are sparse here tree ring cellulose 18o from southern california is used to assess the potential of this proxy as an indicator of long term hydroclimate and atmospheric variability from 1954 to 2004 we observed that cellulose 18o was well replicated within a single stand of blue oak quercus douglasii on interannual and decadal time scales by using a forward mechanistic model we demonstrate that cellulose 18o is not driven solely by the oxygen isotope composition of precipitation at the site nor any other single hydroclimate variable instead the interannual variability in cellulose 18o prior to 1979 is positively correlated with growing season soil water 18o and after 1979 is negatively correlated with relative humidity in addition 2 years 1983 and 1998 of anomalously low cellulose 18o coincided with the wettest years in california and the strongest el nino events of the late 20th century for these years decreased near surface evaporation and or increased upper level condensation could account for the more depleted cellulose 18o values while blue oak cellulose 18o is sensitive to atmospheric and hydroclimate variability the varying temporal correlation between the cellulose 18o and different environmental variables complicates any attempt to use the cellulose oxygen isotopes for reconstructions of climate variability beyond the calibration period

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

individual and pooled tree ring stable carbon isotope series in chinese pine from the nan wutai region china common signal and climate relationships abstract to investigate the differences in the climatic signals in stable carbon isotopic composition captured by averaging series from individual trees versus raw wood of trees pooled prior to analysis we analyzed two groups of chinese pine pinus tabulaeformis carr from the nan wutai region of the qinling mountains china one group included three trees that were analyzed separately and the other group comprised four other trees that were pooled prior to preparation and analysis all 13 c series were positively correlated r 0 50 0 58 p 13 c of atmospheric co 2 correlations between the meteorological data and all individual and pooled discrimination 13 c series revealed significant negative responses to temperature for several specific months and for mean january to september t j s temperature we used a numerical mix method nmm equivalent to unweighted mean by averaging individual 13 c series nps1 nps2 nps3 to generate a new series that more strongly correlated to climate series t j s r 0 67 p j s is significant for plant growth and is consistent with the tree physiology in this region our results suggest that the numerical mix method with tree ring stable isotope data from three trees provides a series quite satisfactory for climatic reconstruction the relationship of the numerical mix model 13 c with temperature was stronger than for the pooled series suggesting numerical mixing of series can be more effective than raw wood sample pooling at least according to the trees in this study

subglacial and ice contact volcanism at the oraefajokull stratovolcano iceland eruptions of oraefajokull have produced mafic and silicic magmas and have taken place in both glacial and interglacial periods the geology of the volcano records the differing response of magmas of contrasting composition to interaction with ice of variable thickness and gives insight into the development of a long lived ice covered stratovolcano vatnafjall a ridge on the southeast flank of oraefajokull is the first area of the volcano to have been mapped in detail and the geological map is presented here alongside descriptions of each erupted unit the oldest units comprise pillow lavas hyaloclastite and jointed lava flows that were formed during subglacial basaltic eruptions involving abundant meltwater the products of a subsequent explosive initially phreatomagmatic subglacial rhyolite eruption were confined by ice to form a tephra pile over 200 m thick that was intruded by dense rhyolite magma towards the end of the eruption confinement by ice caused a later trachydacite lava flow to form buttresses and a steep pillar whilst some of the meltwater produced infiltrated the lava to generate red and black glassy breccias and cause localised steam explosions it is likely that much of it drained down the steep topography the most recently erupted units are subaerial basaltic lava flows the oldest of which were erupted during an interglacial period and have subsequently been partially eroded and scoured by advancing ice ice has been important in shaping the edifice by confining eruptive products to form constructional features and by later eroding parts of them to form deep valleys reconstructions of volcano ice interaction allowed the local thickness of the glacier at the time of each eruption to be estimated and demonstrates that the upper surface of the ice has varied in elevation by over 700 m

improving a tree ring reconstruction from west central scandinavia 900 years of warm season temperatures dendroclimatological sampling of scots pine pinus sylvestris l has been made in the province of jamtland in the west central scandinavian mountains since the 1970s the tree ring width trw chronology spans several thousand years and has been used to reconstruct june august temperatures back to 1632 bc a maximum latewood density mxd dataset covering the period ad 1107 1827 with gap 1292 1315 was presented in the 1980s by fritz schweingruber here we combine these historical mxd data with recently collected mxd data covering ad 1292 2006 into a single reconstruction of april september temperatures for the period ad 1107 2006 regional curve standardization rcs provides more low frequency variability than non rcs and stronger correlation with local seasonal temperatures 51 variance explained the mxd chronology shows a stronger relationship with temperatures than the trw data but the two chronologies show similar multi decadal variations back to ad 1500 according to the mxd chronology the period since ad 1930 and around ad 1150 1200 were the warmest during the last 900 years due to large uncertainties in the early part of the combined mxd chronology it is not possible to conclude which period was the warmest more sampling of trees growing near the tree line is needed to further improve the mxd chronology

stability of climate signal in carbon and oxygen isotope records and ring width from scots pine pinus sylvestris l in finland four hundred year long records of carbon and oxygen stable isotope ratios and ring width were measured from scots pine pinus sylvestris l from sites in northern and eastern finland responses of isotope ratios to temperature and precipitation were analysed for the 20th century carbon isotope ratios responded strongly to summer temperature at both sites whereas an influence of precipitation on the record was observed only at the site in eastern finland oxygen isotope ratios were less responsive to climatic variation than carbon at the high frequency level to shed light on the role of the possible divergence problem during last decades the climate responses were studied separately in the first and in the second half of the 20th century the responses to temperature were stable in the north but in eastern finland the significant period of summer occurred earlier during the later half of the century relationships between records were studied during the 400 a period all proxies correlated positively with each other although temporal changes occurred common forcing discovered in northern finland between carbon isotope and ring width records was weaker in the earlier period studied three climate reconstructions were created temperature reconstruction for northern finland and temperature and precipitation reconstructions for eastern finland copyright 2009 john wiley sons ltd

do tree ring δ13c series from pinus sylvestris in northern fennoscandia contain long term non climatic trends abstract non climatic trends in tree ring 13 c series are investigated using highly replicated pinus sylvestris 13 c series from finnish lapland the declining trend in stable carbon isotopes over the industrial period reflecting changes in the isotopic ratio of atmospheric co 2 is removed mathematically without recourse to statistical de trending regional curve standardisation rcs is then used to identify and remove the juvenile phase during which 13 c values increase the chronologies all show approximately 1 depletion in the juvenile phase with an average rise of 0 029 year 1 lasting for about 50 years after which trees of very different cambial age capture common variance over the same chronological period there is no evidence of long term age related trends and rcs provides an alternative to simply omitting the juvenile portion of the stable carbon isotope series thus allowing greater sample depth to be retained

monsoon precipitation variation recorded by tree ring δ18o in arid northwest china since ad 1878 abstract the east asian summer monsoon easm precipitation from may to august over the helan mountains located in the northwest margin of the easm has been investigated through tree ring 18o for the last 120 years the dry and wet intervals derived from the 18o series can be verified by the tree ring width based may july precipitation reconstruction most of the time the 18o series and ring width derived precipitation reconstruction vary synchronously at low frequency high values of 18o correspond to high precipitation periods and vice versa since the 1970s the east asian summer monsoon precipitation has been increasing which was confirmed by other records and documents our results show that tree ring 18o can serve as an indicator of the strength of the east asian summer monsoon variation in the past we also found that tree ring 18o varies inversely to 13c in the study area

spatial and temporal oxygen isotope trends at the northern tree line in eurasia 1 the oxygen isotope ratio of ice cores and sea sediments is an extremely useful source of information on long term climatic changes a similar approach has been applied to the oxygen isotope ratio of tree rings to enable a pattern based reconstruction of the isotope variations on the continents we present an oxygen isotope map for northern eurasia spanning from norway to siberia that reflects the isotope distribution in the late 19th century and compare it with an equivalent map for the present day situation the average isotope values of 130 trees show a large east to west gradient and are highly correlated with the isotope distribution of precipitation surprisingly the 18o 16o ratio of the wood has been decreasing in the interior of the continent since the late 19th century in contrast to the strong temperature increase recorded by meteorological data from this isotope trend over time a change in the seasonality of precipitation can be inferred

assessing tree ring carbon and oxygen stable isotopes for climate reconstruction in the canadian northeastern boreal forest abstract in this study we analyzed stable isotopes of oxygen 18o and carbon 13c of five black spruce picea mariana mill bsp trees growing in the quebec boreal forest we then produced the first dendroisotopic series covering the last two centuries 1800 2003 for this region where climatic records are particularly scarce and of short duration our aim was to evaluate the isotope sensitivity to climate and their potential as proxies for past climate conditions the 18o results show a strong coherence between all trees indicating that these values express a homogenous response at the site scale for the 13c series slight inter tree differences suggest the influence of micro site conditions isotopic values were compared to climatic data for the period 1944 2003 these statistical analyses indicate that the 13c and 18o ratios are directly influenced by summer maximum temperatures but also correlate with parameters that integrate temperatures and moisture status in all cases the climate effects on 13c values are weaker than the ones recorded by the 18o series moreover because the 18o and 13c values are sensitive to climatic variables that are linked and commonly associated in typical subarctic climate ambiances warm dry cold wet the patterns of their joint response show stronger correlations with climatic parameters then a temperature reconstruction was developed based on a regression model that calibrates the combined 13c and 18o series against summer maximum temperature tmaxjja the reconstructed summer temperatures indicates that the first half of the 19th century was the coldest period in the past 200 years and that a steadily change throughout milder conditions started in the early 1940 s these trends are consistent with other reconstructed values from independent proxies available for the same region this research confirms that c and o dendroisotopic series of black spruce trees in high latitudes can document adequately past climatic conditions

tree ring isotopic pooling without regard to mass no difference from averaging δ13c values of each tree abstract pooling of growth rings from several trees before subsequent isotopic analysis of the mixture may offer the advantage of obtaining representative isotopic values fairly rapidly in principle however unless equal masses are taken from the individuals to make the composite sample the measured isotope value will be biased by the relative mass contribution of the trees each of which likely has a different isotopic composition although biasing associated with direct pooling without regard to mass may happen this study provides evidence at least for stable carbon isotope composition from three sites in the u s midwest and southwest that the error probably more appropriately called difference is negligible with respect to error of preparation and analysis and variability of isotopic composition within and among trees at a site

climate signals in tree ring width density and δ13c from larches in eastern siberia russia abstract we present the first and longest 413 years dataset on stable carbon isotope ratios in tree ring cellulose 13c tree ring width trw and maximum latewood density mxd obtained from larch trees growing on permafrost under continental climate in the suntar khayata mountain ridge in eastern siberia russia with this first study we calibrate tree ring parameters against climate quantities and based on these results assess the potential added value of mxd and especially of 13c complementing trw analysis for future climate reconstruction purposes 13c chronologies were corrected for human induced changes in atmospheric co2 since ad 1800 two different approaches were compared i a correction referring merely to the decline in atmospheric 13c 13catm and ii a correction additionally accounting for the increase in atmospheric partial pressure of co2 13c chronologies are characterized by strong signal strength with only 4 trees representing the population signal at the site mean inter series correlation 0 71 and eps 0 90 13c variation shows low similarity to trw and mxd while correlation between trw and mxd is highly significant correlation analysis of tree ring parameters with gridded instrumental data climate research unit cru ts 2 1 over the ad 1929 2000 calibration period demonstrates that trw and mxd react as reported from other sites at cold and humid northern latitudes precipitation plays no significant role but strong dependencies on monthly mean maximum and minimum temperatures particularly of the current summer june to august are found up to r 0 60 p

twentieth century summer temperature variability in the southern altai mountains a carbon and oxygen isotope study of tree rings the altai mountains southern siberia represent an area of significant scientific interest and exceptional palaeoecological potential to assess the influence of climate on the stable isotopic composition of tree ring cellulose and the potential of this record as a palaeoclimate proxy replicated stable oxygen and carbon isotope time series were developed for the twentieth century from four siberian pine pinus sibirica du tour trees growing near the settlement of aktash russian altai mountains southern siberia bootstrapped calibrations for the local instrumental period ad 1954 2000 reveal strong correlations between summer july august growing season temperatures and tree ring oxygen r2 0 55 and carbon r2 0 30 isotopes covariance observed between both carbon and oxygen isotope data suggest a common stomatal control the resulting empirical model was used to reconstruct regional summer temperatures for the twentieth century no divergence is observed between the non detrended tree ring isot

a 500 year record of summer near ground solar radiation from tree ring stable carbon isotopes tree ring stable carbon isotope ratios d13c in environments of low moisture stress are likely to be controlled primarily by photosynthetic rate therefore sunshine rather than temperature represents the more direct controlling factor temperature reconstructions based on tree ring d13c results thus rest on the assumption that temperature and sunshine are strongly coupled this assumption is tested using a d13c series from pine trees in nw norway where there are long 100 yr records of both summer temperature and cloud cover it is demonstrated that when summer temperature and d13c diverge summer temperature and cloud cover also diverge and that cloud cover sunshine may provide a stronger and more consistent parameter with which to calibrate tree ring d13c series in this area when a 500 year reconstruction of summer cloudiness is compared with a published reconstruction of summer temperatures in northern sweden based on tree ring maximum densities the two time series are largely parallel with

in search of ancestral kilauea volcano submersible observations and samples show that the lower south flank of hawaii offshore from kilauea volcano and the active hilina slump system consists entirely of compositionally diverse volcaniclastic rocks pillow lavas are confined to shallow slopes submarine erupted basalt clasts have strongly variable alkalic and transitional basalt compositions to 41 sio 2 10 8 alkalies contrasting with present day kilauea tholeiites the volcaniclastic rocks provide a unique record of ancestral alkalic growth of an archetypal hotspot volcano including transition to its tholeiitic shield stage and associated slope failure events

stable carbon isotope ratios of pinus sylvestris from northern finland and the potential for extracting a climate signal from long fennoscandian chronologies stable carbon isotope ratios were measured on the latewood cellulose of 36 scots pine trees from four sites in northern finland 13c values were corrected for changes in the 13c of air and de trended to remove the effect of tree age simple linear and multivariate correlations were used to determine the nature and strength of any climate signal at three sites the dominant controls are in descending order summer sunshine temperature and antecedent precipitation at the fourth site the dominant controls are antecedent precipitation and air relative humidity while summer sunshine and temperature appear unimportant 13c values record changes in the concentration of co2 in the stomatal chambers which reflects the balance between stomatal conductance and photosynthetic rate photosynthetic rate is controlled primarily by photon flux sunshine and temperature suggesting that this dominates at three of the sites whereas stomatal conductance is controlled by air humidity and soil moisture status ant

towards a reconstruction of blue nile baseflow from ethiopian tree rings most of the water in the river nile originates from monsoonal rainfall over the ethiopian highlands despite warnings of future climate change little is known about the historical variability in this supply particularly at annual resolution development of tree ring records in this region has been limited by the occurrence of bi or multimodal rainfall regimes causing the development of multiple growth rings that cannot be dated with confidence in this study we identified annual rings in 30 juniperus procera trees from northwest ethiopia by dendrochronology and ams radiocarbon dating carbon isotope ratios 4 series and ring widths 73 series were measured the carbon isotope series did not contain strong trends possibly attributable to increased anthropogenic atmospheric co2 concentrations or the juvenile effect both carbon isotope values and ring widths were strongly correlated with blue nile baseflow and from composite chronology indices r 0 75 p 0 01 a preliminary reconstruction of blue nile baseflow back to ad 1836 was developed subsample signal strength remained above 0 85 for most of the reconstruction uncertainty bands were relatively narrow and the reliability of the preliminary reconstruction was confirmed by correspondence with reported years of drought and famine the preliminary reconstruction is characterized by an exceptional decline in baseflow during the late ad 1960s flows recovered during the late 1990s additional sampling is advised to increase replication spatial coverage and length of the preliminary reconstruction