stable isotope records of late quaternary climate and hydrology from mediterranean lakes the isomed synthesis lake isotope records can be used to assess the spatial coherency of late quaternary climate change across the circum mediterranean region we place modern and palaeo data within a simple conceptual lake response model to show that the isotope hydrology of most mediterranean lakes has been influenced strongly by water balance even in those systems that are chemically dilute i e freshwater 18o data on biogenic and endogenic carbonates from 24 lake basins are used to reconstruct multi millennial scale trends since the lgm while it is difficult to make direct comparisons between lake records in terms of single climatic parameters coherent regional isotopic trends can be identified during glacial times mediterranean lakes deposited carbonates isotopically heavier in 18o compared to the holocene partly due to source area effects isotopic enrichment was most marked during intervals corresponding to the h1 and younger dryas events confirming that late pleistocene cold stages in the north atlantic region were marked by aridity around much of the mediterranean almost all mediterranean lake records shifted to more depleted isotopic values during the last glacial interglacial transition lgit this shift is the reverse of the trend which characterised the same transition in lakes from northern and central europe and suggests that temperature changes were not an important direct driver of mediterranean lake isotopic records over glacial interglacial timescales in the early holocene many lakes in the eastern part of the region were more depleted isotopically than in recent millennia this corresponds with marine sapropel formation both chronologically and geographically and implies that increases in local rainfall contributed significantly to the creation of a freshwater lid and anoxia in the east mediterranean sea in contrast no such pattern is currently apparent from lake isotope records from the west mediterranean suggesting a possible nw se contrast in climate history during the holocene

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

solar forcing of nile discharge and sapropel s1 formation in the early to middle holocene eastern mediterranean we present high resolution records for oxygen isotopes of the planktic foraminifer globigerinoides ruber 18oruber and bulk sediment inorganic geochemistry for holocene age sediments from the southeast mediterranean our 18oruber record appears to be dominated by nile discharge rather than basin scale salinity temperature changes nile discharge was enhanced in the early to middle holocene relative to today the timing of the long term maximum in nile discharge during the early holocene corresponds to the timing of maximum intensity of the indian ocean influenced southwest indian summer monsoon sim this coincidence suggests a major influence of an indian ocean moisture source on nile discharge in the early to middle holocene while presently the atlantic ocean is the main moisture source nile discharge was highly variable on multicentennial time scale during the early to middle holocene being strongly influenced by variable solar activity this solar driven variability is also recorded in contemporaneous sim records however not observed in an atlantic ocean derived west african summer monsoon record from the holocene this supports the hypothesis that the indian ocean moisture source predominantly controlled nile discharge at that time solar driven variability in nile discharge also influenced paleoenvironmental conditions in the eastern mediterranean bulk sediment ba al and v al used as indicators for export productivity and redox conditions respectively varied both in response to solar forcing on multicentennial time scales we suggest that changes in nile discharge on these time scales have been concordant with nutrient inputs to and shallow ventilation of the eastern mediterranean

fluctuation in leaf wax d h ratio from a southern california lake records significant variability in isotopes in precipitation during the late holocene abstract the hydrogen isotopic composition of plant molecular markers in modern vegetation and marine sediments in southern california have been intensively studied here we report a late holocene reconstruction from zaca lake in coastal southern california together with modern hydrological and vegetation studies in the catchment the small catchment and decadal sampling resolution throughout the 9 m 3000 yr sedimentary record provided a high resolution terrigenous counterpart of nearby marine records from the santa barbara basin today d values of precipitation average 51 5 18 1 n 7 modern plant leaf wax d values for the c 28 n alkanoic acid averaged 141 11 1 n 10 for quercus agrifolia with a calculated fractionation relative to precipitation e wax precip of 94 22 1 n 10 in contrast there was negligible production of the c 28 acid by co dominant pinus coulteri downcore the c 28 acid d values ranged between 101 and 177 mean 150 8 1 n 490 abundance distributions suggested that the sedimentary c 28 acid was dominated by quercus implying that paleoprecipitation varied between extremes of 8 and 92 mean 63 14 compound 1 n 490 the 3000 yr leaf wax d h record from zaca lake revealed substantial temporal variability greater than observed in a speleothem reconstruction of similar resolution we suggest that the plant based proxy may magnify the variability by sampling spring precipitation preferentially centennial duration positive isotopic excursions were associated with more sub tropical moisture sources and drier conditions including during the medieval climatic anomaly and negative excursions were associated with n pacific sources and wetter conditions including during the little ice age

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

timing and climate forcing of volcanic eruptions for the past 2 500 years volcanic eruptions contribute to climate variability but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual to decadal temperature variability in the northern hemisphere during the past 2 500 years our results are based on new records of atmospheric aerosol loading developed from high resolution multi parameter measurements from an array of greenland and antarctic ice cores as well as distinctive age markers to constrain chronologies overall cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth century pandemics famines and socioeconomic disruptions in eurasia and mesoamerica while allowing multi millennium quantification of climate response to volcanic forcing

a mid european decadal isotope climate record from 15 500 to 5000 years b p oxygen isotope ratios of precipitation delta18op inferred from deep lake ostracods from the ammersee southern germany provide a climate record with decadal resolution the record in detail shows many of the rapid climate shifts seen in central greenland ice cores between 15 000 and 5000 years before the present b p negative excursions in the estimated delta18op from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the north atlantic deviating millennial scale trends however indicate that climate gradients between europe and greenland changed systematically reflecting a gradual rearrangement of north atlantic circulation during deglaciation

the marysvale natural analog study preliminary oxygen isotope relations rocks of and around the marysvale mining area in central utah u s a have experienced massive subsolidus hydrothermal exchange with heated meteoric waters plutonic granitic rocks in the central mining area have 18o values ranging from 6 7 to as low as 0 1 quartz monzonite samples from surface exposures have on the average x 2 9 lower 18o values than subsurface samples x 4 3 within the limitations of present data 18o depletions of the intrusive rocks are not obviously correlated to proximity of known major fractures the 18o data are consistent with hydrothermal modifications of normal igneous rocks initially 7 by groundwater initially of 14 at temperatures on the order of 200 c preliminary estimates of integrated water rock ratios range from 0 1 to 1 for plutonic rocks the hydrothermal solutions responsible for the mineralization were derived from meteoric water samples immediately adjacent to a quartz monzonite granite contact show symmetrical 18o depletion which may indicate that the contact was a feature allowing greater flow and or residence time of the hydrothermal solution and that the hydrothermal event apparently postdates granite emplacement

cat scan analysis of sedimentary sequences an ultrahigh resolution paleoclimatic tool paleoclimate research is essential to determine the natural variability of climate and to place the current climate change into its natural context the current need is to generate the highest temporal resolution paleoclimatic reconstructions possible in order to assess the natural variability of the climate system but also to test the ability of numerical models to simulate conditions different from the ones observed with the relatively short instrumental records in this paper we show that cat scan analysis of sedimentary sequences with its 1 mm downcore resolution can be used to identify millennial to seasonal cycles in sedimentary sequences in examples from the st lawrence estuary eastern canada spectral analysis of the cat scan data from holocene postglacial sediments revealed millennial to centennial scale oscillations possibly associated with either solar variability changes in relative sea level or tidal amplitude similarly spectral analysis of holocene and sangamonian glaciomarine sequences revealed decadal to annual scale oscillations with periods close to the one previously associated with the north atlantic oscillation nao whereas spectral analysis of the cat scan data from the sangamonian rhythmites possibly revealed seasonal cycles

calderas of the marysvale volcanic field west central utah five calderas three creeks big john monroe peak mount belknap and red hills have been identified and a sixth lion flat tentatively identified in the middle tertiary marysvale volcanic field of western utah the calderas are manifestations of separate magma bodies that worked their way to shallow depths between 27 and 19 ma no coherent ash flow field exists in the marysvale volcanic field instead the ash flow units are interleaved at different places in the general volcanic sequence the magma chambers that vented ash flows and collapsed as calderas formed discrete high level plutons they are probably underlain by a deep composite batholith consisting of many individual plutons from two distinct petrogenetic types calc alkalic and bimodal mafic silicic the four largest calderas can be separated into two groups by contrasting structural behavior the three creeks and big john calderas are broad faulted downwarps that sagged into relatively deep magma chambers whose roofs were sufficiently strong to inhibit development of ring faults in contrast the monroe peak and mount belknap calderas are subcircular calderas that collapsed into shallow magma chambers with thin roofs so easily breached that large volumes of lava were erupted within the calderas neither type shows strong postcollapse resurgence roofs above the deeper magma chambers were too strong to be uplifted and those above the shallow chambers were too weak to contain the magmatic pressures

abrupt holocene climate transitions in the northern north atlantic region recorded by synchronized lacustrine records in iceland abstract two high sediment accumulation rate icelandic lakes the glacial lake hvitarvatn and the non glacial lake haukadalsvatn contain numerous tephra layers of known age which together with high resolution paleomagnetic secular variations allow synchronization with a well dated marine core from the shelf north of iceland a composite standardized climate record from the two lakes provides a single time series that efficiently integrates multi proxy data that reflect the evolution of summer temperatures through the holocene the first order trends in biogenic silica bsi 13c and c n rise relatively abruptly following deglaciation reaching maximum values shortly after 8 ka following a complex minimum between 8 7 and 8 0 ka the holocene thermal maximum htm in the lakes is marked by all proxies with a sharp transition out of the 8 ka cold event into peak summer warmth by 7 9 ka and continuing warm with some fluctuations until 5 5 ka decreasing summer insolation after the htm is reflected by incremental cooling initially 5 5 ka with subsequent cold perturbations recorded by all proxies 4 3 to 4 0 ka and 3 1 to 2 8 ka the strongest disturbance occurred after 2 ka with initial summer cooling occurring between 1 4 and 1 0 ka followed by a more severe drop in summer temperatures after 0 7 ka culminating between 0 5 and 0 2 ka following each late holocene cold departure bsi re equilibrated at a lower value independent of the sediment accumulation rate some of the abrupt shifts may be related to icelandic volcanism influencing catchment stability but the lack of a full recovery to pre existing values after the perturbation suggests increased periglacial activity decreased vegetation cover and glacier growth in the highlands of iceland the similarity in timing direction and magnitude of our multi proxy records from glacial and non glacial lakes and from the adjacent marine shelf suggests that our composite record reflects large scale shifts in ocean atmosphere circulation throughout the northern north atlantic

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

regional temperature atmospheric circulation and sea ice variability within the younger dryas event constrained using a speleothem from northern iberia precisely dated high resolution stable isotope and trace element data from a stalagmite from la garma cave northern spain reveal several stages of distinct climatic variability along the northern iberian atlantic margin and provide new constraints on the latitude of north atlantic westerlies during the younger dryas event yd westerly wind position reconstructed using sub annually resolved mg data as a proxy for sea spray contributions associated with wind strength at this coastal cave site during the early yd 12 85 12 15 kyr oscillated meridionally resembling the decadal scale component of the modern north atlantic oscillation nao northward repositioning of westerly storm tracks over northern iberia began at 12 15 kyr consistent with other high resolution wind proxy reconstructions from central and northern europe but occurred more gradually nearer the atlantic margin from 12 15 kyr to the yd termination atmospheric circulation resembled a persistently positive nao with westerlies reaching their maximum northward extent at 11 8 kyr reflected by a mg concentration minimum at this time air temperature reflected by our 18o data and iberian wind strength were predominantly coupled throughout the yd suggesting that temperature modulated sea ice extent and consequently controlled westerly wind latitude however our data suggest that abrupt warming at 12 1 kyr was followed by much more gradual northward shifts in westerly position and that a lag existed between the warming and sea ice retreat this gradual return of the westerlies to the north beginning at 12 1 kyr is consistent with inferred changes in wind strength at other european sites additionally atmospheric circulation inferred from our northern iberian wind strength proxy record generally tracked low frequency meridional shifts in intertropical convergence zone position corroborating past research that suggested closely coupled low and high latitude atmospheric teleconnections over this period

meltwater pulse 1a from antarctica as a trigger of the bolling allerod warm interval meltwater pulse 1a mwp 1a was a prominent feature of the last deglaciation which led to a sea level rise of 20 meters in less than 500 years concurrent with mwp 1a was the onset of the bolling allerod interstadial event 14 600 years before the present which marked the termination of the last glacial period previous studies have been unable to reconcile a warm northern hemisphere with mwp 1a originating from the laurentide or fennoscandian ice sheets with the use of a climate model of intermediate complexity we demonstrate that with mwp 1a originating from the antarctic ice sheet consistent with recent sea level fingerprinting inferences the strength of north atlantic deep water nadw formation increases thereby warming the north atlantic region and providing an explanation for the onset of the bolling allerod warm interval the established mode of active nadw formation is then able to respond to subsequent freshwater forcing from the laurentide and fennoscandian ice sheets setting the stage for the younger dryas cold period the melting of continental ice sheets during the last deglaciation provided a freshwater source to the ocean that affected global sea level and the strength of the thermohaline circulation an exceptionally large melting event inferred from far field relative sea level records occurred

plant wax d h ratios in the southern european alps record multiple aspects of climate variability we present a younger dryas holocene record of the hydrogen isotopic composition of sedimentary plant waxes d wax from the southern european alps lake ghirla n italy to investigate its sensitivity to climatic forcing variations in this mid latitude region 45 n a modern altitudinal transect of d values of river water and leaf waxes in the lake ghirla catchment is used to test present day climate sensitivity of d wax while we find that altitudinal effects on d wax are minor at our study site temperature precipitation amount and evapotranspiration all appear to influence d wax to varying extents in the lake sediment record d wax values vary between 134 and 180 over the past 13 kyr the long term holocene pattern of d wax parallels the trend of decreasing temperature and is thus likely forced by the decline of northern hemisphere summer insolation shorter term fluctuations in contrast may reflect both temperature and moisture source changes during the cool younger dryas and little ice age lia periods we observe unexpectedly high d wax values relative to those before and after we suggest that a change towards a more d enriched moisture source is required during these intervals in fact a shift from northern n atlantic to southern n atlantic western mediterranean sea sources would be consistent with a southward migration of the westerlies with climate cooling prominent d wax fluctuations in the early and middle holocene are negative and potentially associated with temperature declines in the late holocene 4 kyr bp excursions are partly positive as for the lia suggesting a stronger influence of moisture source changes on d wax variation in addition to isotopic fractionations of the hydrological cycle changes in vegetation composition in the length of the growing season and in snowfall amount provide additional potential sources of variability although we cannot yet quantitatively assess these in the paleo record we conclude that while our d wax record from the alps does contain climatic information it is a complicated record that would require additional constraints to be robustly interpreted this also has important implications for other water isotope based proxy records of precipitation and hydro climate from this region such as cave speleothems

comnispa ii update of a mid european isotope climate record 11 ka to present we present an update comnispa ii of a precisely dated high resolution speleothem 18o record from the austrian alps comnispa ii consists of five stalagmites from spannagel cave which have comp

comparison of oxygen isotope records from the gisp2 and grip greenland ice cores recent results1 2 from the greenland ice core project grip summit ice core suggest that the climate in greenland has been remarkably stable during the holocene but was extremely unstable for the time period represented by the rest of the core spanning the last two glaciations and the intervening eemian inter glacial here we present the complete oxygen isotope record for the greenland ice sheet project 2 gisp2 core drilled 28 km west of the grip core we observe large rapid climate fluctuations throughout the last glacial period which closely match those reported for the grip core however in the bottom 10 of the cores spanning the eemian interglacial and the previous glacia tion there are significant differences between the two records it is possible that ice flow may have altered the chronological sequences of the stratigraphy for the bottom part of one or both of the cores considerable further work will be necessary to evaluate the likelihood of this and the extent to which it will still be possible to extract meaningful climate information from the lowest sections of the cores

orbital and solar forcing of shifts in mid to late holocene flood intensity from varved sediments of pre alpine lake ammersee southern germany abstract microfacies analyses and x ray fluorescence scanning xrf at sub mm resolution were conducted on the varved mid to late holocene interval of two sediment profiles from pre alpine lake ammersee southern germany the coring sites are located in a proximal as10prox and distal as10dist position towards the main tributary river ammer in 1 8 km distance from each other to shed light on sediment distribution within the lake particular emphasis was 1 the detection of intercalated detrital layers and their micro sedimentological features and 2 intra basin correlation of these event deposits detrital layers were dated by microscopic varve counting verified by accelerator mass spectrometry 14c dating of terrestrial plant macrofossils since 5500 varve years vyr bp in total 1573 detrital layers were detected in either one or both of the investigated sediment profiles based on their microfacies geochemistry and proximal distal deposition pattern detrital layers were interpreted as river ammer flood deposits earlier studies on flood layer seasonality have proven that flood layer deposition occurs predominantly during spring and summer the flood season at lake ammersee most prominent features of the record are the onset of regular flood layer deposition at 5500 vyr bp in as10prox and 2800 vyr bp in as10dist as well as three major increases in mean flood layer thickness at 5500 2800 and 400 vyr bp integrating information from both sediment profiles allowed to interpret these changes in terms of shifts towards higher mean flood intensity proposed triggering mechanisms are gradual reduction in northern hemisphere orbital summer forcing and superimposed centennial scale solar activity minima likely responses to this forcing are enhanced equator to pole temperature gradients and changes in synoptic scale atmospheric circulation the consequences for the ammersee region are more intense cyclones leading to extremer rainfall and flood events in spring and summer

patterns of oxygen isotope depletion multiple hydrothermal circulation systems and the cooling history of the stony mountain intrusive complex colorado abstract oxygen isotopic compositions of 27 whole rock and mineral samples from the three intrusive phases of the stony mountain stock san juan mountains colorado have been measured and are combined with published analyses to obtain a history of the meteoric water circulation that cooled the intrusions the order of intrusion was the outer diorite the gabbro and the inner diorite the new whole rock data give 18 o smow 1 9 to 3 7 for the gabbro and 0 4 to 4 9 for the inner diorite five mineral analyses are reported for the inner diorite three feldspars ranging from 0 2 to 4 3 one quartz 8 2 and one pyroxene 5 3 all three intrusions are significantly depleted in 18 o relative to normal igneous rocks this depletion occurred by subsolidus exchange of oxygen isotopes as shown by the correlation between the extent of depletion and the grain size and by the non equilibrium 18 o concentrations in coexisting minerals the patterns of 18 o depletion which are complex suggest that separate hydrothermal circulation systems were set up by the cooling of each intrusion in turn the minimum water to rock ratio required to effect the observed depletion in the inner diorite is approximately 0 18 although the ratio for the total flux was probably much greater the mineral data show marked 18 o depletion in the feldspars and little if any depletion in the quartz application of oxygen diffusion data for feldspar and quartz leads to the conclusion that the effective temperature for oxygen isotope exchange was below 600 c and above 400 c furthermore these data place constraints on convective cooling times for this intrusion minimum times for cooling of the 500 m diameter inner diorite through this temperature range are on the order of 14 to 900 years for comparison a maximum time limit of 4000 years would be needed if cooling occurred only by conduction

lateglacial and early holocene summer temperatures in the southern swiss alps reconstructed using fossil chironomids we present a lateglacial and early holocene chironomid based july air temperature reconstruction from foppe 1470 m a s l in the swiss southern alps our analysis suggests that chironomid assemblages have responded to major and minor climatic fluctuations during the past 17 000 years such as the oldest dryas the younger dryas and the bolling allerod events in the lateglacial and the preboreal oscillation at the beginning of the holocene quantitative july air temperature estimates were produced by applying a combined norwegian and swiss temperature inference model consisting of 274 lakes to the fossil chironomid assemblages the foppe record infers average july air temperatures of ca 9 9 8c during the oldest dryas 12 2 8c during most of the bolling allerod and 11 1 8c for the younger dryas mean july air temperatures during the preboreal were 14 8c major temperature changes were observed at the oldest dryas bolling 2 7 8c the allerod younger dryas 2 8c and the younger dryas holocene transitions 3 9 8c the temperature reconstruction also shows centennial scale coolings of ca 0 8 1 4 8c which may be synchronous with the aegelsee greenland interstadial 1d and the preboreal oscillations a comparison of our results with other palaeoclimate records suggests noticeable temperature gradients across the alps during the lateglacial and early holocene copyright 2011 john wiley sons ltd

sea surface temperature variations in the western mediterranean sea over the last 20 kyr a dual organic proxy uk 37 and ldi approach a high resolution sea surface temperature sst reconstruction of the western mediterranean was accomplished using two independent algae based molecular organic proxies i e the u 37 k index based on long chain unsaturated ketones and the novel long chain diol index ldi based on the relative abundances of c 28 and c 30 1 13 and 1 15 diols two marine records from the western and eastern alboran sea basin spanning the last 14 and 20kyr respectively were studied results from the surface sediments suggest that the two proxies presently reflect seasons with similar sst or simply annual mean sst both proxy records reveal the transition from the last glacial maximum to the holocene in the eastern alboran sea with an sst increase of approximately 7 degrees c for u 37 k and 9 degrees c for ldi minimum ssts 10 12 degrees c are reached at the end of the last glacial maximum and during the last heinrich event with a subsequent rapid sst increase in ldi sst toward the beginning of the bolling period 20 degrees c while u 37 k sst remains constantly low similar to 12 degrees c the bolling allerod period is characterized by a rapid increase and subsequent decrease in u 37 k sst while the ldi sst decrease continuously short term fluctuations in u 37 k sst are probably related to the availability of nutrients and seasonal changes the younger dryas is recorded as a short cold interval followed by progressively warmer temperatures during the holocene the general lower u 37 k derived temperature values in the eastern alboran by approximately 1 5 2 degrees c suggest a southeastward cold water migration by the western alboran gyre and divergence in the haptophyte blooming season between both basins key points high resolution sst reconstruction is performed in the westernmost mediterranean two algae based proxies show the temperature evolution for the last 20 kyr derived ssts suggest different growth seasons of alkenone and diol producers

the global response to younger dryas boundary conditions in an agcm simulation geological evidence points to a global younger dryas yd climatic oscillation during the last glacial present interglacial transition phase a convincing mechanism to explain this global yd climatic oscillation is not yet available nevertheless a profound understanding of the mechanism behind the yd climate would lead to a better understanding of climate variability

holocene atmosphere ocean interactions records from greenland and the aegean sea we compare paleoclimate proxy records from central greenland and the aegean sea to offer new insights into the causes timing and mechanisms of holocene atmosphere ocean interactions a direct atmospheric link is revealed between aegean sea surface temperature sst and high latitude climate the major holocene events in our proxies of aegean sst and winter spring intensity of the siberian high gisp2 k record follow an 2300 year spacing recognised also in the 14c record and in worldwide holocene glacier advance phases suggesting a solar modulation of climate we argue that the primary atmospheric response involved decadal centennial fluctuations in the meridional pressure gradient driving aegean sst events via changes in the strength duration and or frequency of northerly polar continental air outbreaks over the basin the observed natural variability should be accounted for in predictions of future climate change and our timeframe for the aegean climate events in addition provides an independent chronostratigraphic argument to middle eastern archaeological studies

correlation of in situ modulus of deformation with degree of weathering rmr and q system geotechnical investigation projects in korea produced data on the in situ modulus of deformation of rock masses em measured with the borehole test rock mass rating rmr and q system the modulus of deformation of rock masses was correlated with the degree of weathering rmr and q values determination of em for each degree of weathering allows for the results to be used to classify the degree of weathering or to predict em the relation between em and rmr is represented by e text m 10 frac text rmr 16 50 which returns values 2 3 times lower than those reported in previous studies despite scatter in the values due to larger dataset used in this study the proposed equation may be used to predict the in situ modulus of deformation from rmr values in addition the relation between modulus of deformation and q values is e text m 10 0 32 log q 0 585

variability of the north atlantic oscillation over the past 5 200 years the north atlantic oscillation influences climate in the arctic region and northern europe reconstructions of circulation patterns associated with the north atlantic oscillation from a 5 200 year long lake sediment record suggest that the atmospheric circulation responded to significant transitions in northern hemisphere climate

orbital and millennial scale changes in the hydrologic cycle and vegetation in the western african sahel insights from individual plant wax δd and δ 13 c to reconstruct variability of the west african monsoon and associated vegetation changes on precessional and millennial time scales we analyzed a marine sediment core from the continental slope off senegal spanning the past 44 000 years 44 ka we used the stable hydrogen isotopic composition dd of individual terrestrial plant wax n alkanes as a proxy for past rainfall variability the abundance and stable carbon isotopic composition d 13 c of the same compounds were analyzed to assess changes in vegetation composition c3 c4 plants and density the dd record reveals two wet periods that coincide with local maximum summer insolation from 38 to 28 ka and 15 to 4 ka and that are separated by a less wet period during minimum summer insolation our data indicate that rainfall intensity during the rainy season throughout both wet humid periods was similar whereas the length of the rainy season was presumably shorter during the last glacial than during the holocene additional dry intervals are identified that coincide with north atlantic heinrich stadials and the younger dryas interval indicating that the west african monsoon over tropical northwest africa is linked to both insolation forcing and highlatitude climate variability the d 13 c record indicates that vegetation of the western sahel was consistently dominated by c4 plants during the past 44 ka whereas c3 type vegetation increased during the holocene moreover we observe a gradual ending of the holocene humid period together with unchanging ratio of c3 to c4 plants indicating that an abrupt aridification due to vegetation feedbacks is not a general characteristic of this time interval

a new greenland ice core chronology for the last glacial termination 1 we present a new common stratigraphic timescale for the north greenland ice core project ngrip and grip ice cores the timescale covers the period 7 9 14 8 kyr before present and includes the bolling allerod younger dryas and early holocene periods we use a combination of new and previously published data the most prominent being new high resolution continuous flow analysis cfa impurity records from the ngrip ice core several investigators have identified and counted annual layers using a multiparameter approach and the maximum counting error is estimated to be up to 2 in the holocene part and about 3 for the older parts these counting error estimates reflect the number of annual layers that were hard to interpret but not a possible bias in the set of rules used for annual layer identification as the grip and ngrip ice cores are not optimal for annual layer counting in the middle and late holocene the timescale is tied to a prominent volcanic event inside the 8 2 kyr cold event recently dated in the dye 3 ice core to 8236 years before a d 2000 b2k with a maximum counting error of 47 years the new timescale dates the younger dryas preboreal transition to 11 703 b2k which is 100 150 years older than according to the present grip and ngrip timescales the age of the transition matches the gisp2 timescale within a few years but viewed over the entire 7 9 14 8 kyr section there are significant differences between the new timescale and the gisp2 timescale the transition from the glacial into the bolling interstadial is dated to 14 692 b2k the presented timescale is a part of a new greenland ice core chronology common to the dye 3 grip and ngrip ice cores named the greenland ice core chronology 2005 gicc05 the annual layer thicknesses are observed to be log normally distributed with good approximation and compared to the early holocene the mean accumulation rates in the younger dryas and bolling periods are found to be 47 2 and 88 2 respectively

geotechnical comparison of weathering degree and shear wave velocity in the decomposed granite layer in hongseong south korea as part of a fundamental characterization of a subsurface layer in south korea the weathering degree and shear wave velocity v s were evaluated in a decomposed granite in hongseong using x ray fluorescence analyses and site investigations including borehole drilling with standard penetration test spt and in situ seismic tests the subsurface layer was composed of a weathered layer 10 40 m thick at most sites weathering degree analyses indicated that three chemical weathering indices the modified weathering potential index mwpi vogt ratio vr and weathering index of parker wip generally increased with decreasing depth in situ seismic tests revealed that v s ranged between 200 and 500 m s in the weathered layer using the v s and n values from the spt at borehole seismic testing sites correlations between v s and n values were established for the weathered layer furthermore examination of the relationships of the v s and n values with the mwpi wip and 100 vr indices showed that the index values increased linearly with increasing v s and exponentially with increasing n values

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

the provenance of vegetation and environmental signatures encoded in vascular plant biomarkers carried by the ganges brahmaputra rivers organic matter carried by rivers and deposited in continental and marine sediments contains valuable information on past environmental conditions and their impact on the terrestrial biosphere in order to use sedimentary records to reconstruct past environmental conditions on the continents such as vegetation cover and type or precipitation intensity we need to understand the provenance of the organic signatures and how they are transferred and potentially modified by fluvial transport to the sedimentary reservoir in particular we need to understand how environmental conditions are imprinted in the composition of riverine particulate organic carbon here we investigate the stable carbon and hydrogen isotopic signatures of vascular plant leaf wax biomarkers in the modern day ganges and brahmaputra river complex one of the largest fluvial systems on earth the distribution of n alkanes and n alkanoic acids in ganges brahmaputra river sediments suggests that vascular plant inputs are consistently a significant component of the organic carbon pool molecular 13c measurements reveal that c3 vegetation inputs delivered by the himalayan rivers are partly degraded and replaced by mixed c3 c4 vegetation input in the floodplain the hydrogen isotopic composition of long chain c24 n alkanoic acids in combination with their stable c isotopic composition provides constraints on the isotopic composition of the environmental water used by higher plants within the drainage basin calculated compositions compare well with the depleted d isotopic ratios of the river water during the summer monsoon suggesting that h isotopic compositions of long chain alkanoic acids are a valuable proxy for the composition of summer monsoon moisture in the ganges brahmaputra basin detailed studies of the isotopic anatomy of modern river systems are critical for informed interpretation of marine sedimentary records in river influenced continental margins

alpine evidence for atmospheric circulation patterns in europe during the last glacial maximum the configuration of alpine accumulation areas during the last glacial maximum lgm has been reconstructed using glacial geological mapping the results indicate that the lgm ice surface consisted of at least three major ice domes all located south of the principal weather divide of the alps this implies that the buildup of the main alpine ice cover during oxygen isotope stage ois 2 was related to precipitation by dominant southerly atmospheric circulation in contrast to today s prevalent westerly airflow such a reorganization of the atmospheric circulation is consistent with a southward displacement of the oceanic polar front in the north atlantic and of the associated storm track to the south of the alps these results combined with additional paleoclimate records from western and southern europe allow an interpretation of the asynchronous evolution of the different european ice caps during the last glaciation 18o stages ois 4 and 3 were characterized by location of the polar front north of 46 n gulf of biscay this affected prevailing westerly circulation and thus ice buildup in western scandinavia the pyrenees vosges and northern alps at the lgm however the polar front lay at 44 n causing dominating southerly circulation and reduced precipitation in central and northern europe

reconstruction of temperature in the central alps during the past 2000 yr from a δ18o stalagmite record the precisely dated isotopic composition of a stalagmite from spannagel cave in the central alps is translated into a highly resolved record of temperature at high elevation during the past 2000 yr temperature maxima during the medieval warm period between 800 and 1300 ad are in average about 1 7 8c higher than the minima in the little ice age and similar to present day values the high correlation of this record to d 14 c suggests that solar variability was a major driver of climate in central europe during the past 2 millennia d 2005 elsevier b v all rights reserved

latest pleistocene and holocene glacier variations in the european alps in the alps climatic conditions reflected in glacier and rock glacier activity in the earliest holocene show a strong affinity to conditions in the latest pleistocene younger dryas glacier advances in the alps related to younger dryas cooling led to the deposition of egesen stadial moraines egesen stadial moraines can be divided into three or in some cases even more phases sub stadials moraines of the earliest and most extended advance the egesen maximum stabilized at 12 2 1 0 ka based on 10be exposure dating at the schonferwall tyrol austria and the julier pass outer moraine switzerland final stabilization of moraines at the end of the egesen stadial was at 11 3 0 9 ka as shown by 10be data from four sites across the alps from west to east the sites are piano del praiet northwestern italy grosser aletschgletscher central switzerland julier pass inner moraine eastern switzerland and val viola northeastern italy there is excellent agreement of the 10be ages from the four sites in the earliest holocene glaciers in the northernmost mountain ranges advanced at around 10 8 1 1 ka as shown by 10be data from the kartell site northern tyrol austria in more sheltered drier regions rock glacier activity dominated as shown for example at julier pass and larstig valley tyrol austria new 10be dates presented here for two rock glaciers in larstig valley indicate final stabilization no later than 10 5 0 8 ka based on this data we conclude the earliest holocene between 11 6 and about 10 5 ka was still strongly affected by the cold climatic conditions of the younger dryas and the preboreal oscillation with the intervening warming phase having had the effect of rapid downwasting of egesen glaciers at or slightly before 10 5 ka rapid shrinkage of glaciers to a size smaller than their late 20th century size reflects markedly warmer and possibly also drier climate between about 10 5 ka and 3 3 ka conditions in the alps were not conducive to significant glacier expansion except possibly during rare brief intervals past tree line data from kaunertal tyrol austria in concert with radiocarbon and dendrochronologically dated wood fragments found recently in the glacier forefields in both the swiss and austrian alps points to long periods during the holocene when glaciers were smaller than they were during the late 20th century equilibrium line altitudes ela were about 200 m higher than they are today and about 300 m higher in comparison to little ice age lia elas the larstig rock glacier site we dated with 10be is the type area for a postulated mid holocene cold period called the larstig oscillation presumed age about 7 0 ka our data point to final stabilization of those rock glaciers in the earliest holocene and not in the middle holocene the combined data indicate there was no time window in the middle holocene long enough for rock glaciers of the size and at the elevation of the larstig site to have formed during the short infrequent cold oscillations between 10 5 and 3 3 ka small glaciers less than several km2 may have advanced to close to their lia dimensions overall the cold periods were just too short for large glaciers to advance after 3 3 ka climate conditions became generally colder and warm periods were brief and less frequent large glaciers for example grosser aletschgletscher advanced markedly at 3 0 2 6 ka around 600 ad and during the lia glaciers in the alps attained their lia maximum extents in the 14th 17th and 19th centuries with most reaching their greatest lia extent in the final 1850 1860 ad advance

a δ13c and δ2h leaf wax record from the late quaternary loess paleosoil sequence el paraiso central spain abstract the mediterranean peninsula increasingly suffers from droughts and aridity the first consequences of global climate change in that region precise scenarios for the region s future climate predictions require knowledge about the processes of past climate changes but information about the western mediterranean climate and its history is controversial for this study we applied compound specific 13c and 2h analyses on long chain n alkanes in the 8 m el paraiso loess paleosoil sequence lps central spain to investigate climate and environmental changes during the late quaternary the 13c values are most enriched during marine isotope stage mis 3 indicating more arid conditions while lower values during mis 4 and 2 are interpreted to document more humid conditions low values are also recorded for the holocene colluvium which can at least partly be explained with higher concentrations in atmospheric co2 the 2h values are mostly enriched during the last glacial compared to the holocene we suggest that this is mainly controlled by isotopic effects related to the moisture source yet other possible effects like evapotranspirative enrichment and changes in atmospheric circulation patterns shouldn t be ruled out our results corroborate previous findings based on leaf wax patterns geomorphological records and climate models they all indicate relatively humid conditions during mis 2 compared to more arid phases during mis 3

delayed hydrological response to greenland cooling at the onset of the younger dryas in western europe during the younger dryas cold event about 12 800 years ago environmental change in western europe seems to occur 170 years after cooling over greenland lake sediment analyses confirm this delay and suggest european hydrological and vegetation change occurred only after the build up of sea ice in the north atlantic pushed the westerly wind system south

variability of the western mediterranean sea surface temperature during the last 25 000 years and its connection with the northern hemisphere climatic changes sea surface temperature sst profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a w e latitudinal transect encompassing the gulf of cadiz atlantic ocean the alboran sea and the southern tyrrhenian sea western mediterranean the results document the sensitivity of the mediterranean region to the short climatic changes of the north atlantic ocean particularly those involving the latitudinal position of the polar front the amplitude of the sst oscillations increases toward the tyrrhenian sea indicating an amplification effect of the atlantic signal by the climatic regime of the mediterranean region all studied cores show a shorter cooling phase 700 years for the younger dryas yd than that observed in the north atlantic region 1200 years this time diachroneity is related to an intra yd climatic change documented in the european continent minor oscillations in the southward displacement of the north atlantic polar front may also have driven this early warming in the studied area during the holocene a regional diachroneity propagating west to east is observed for the sst maxima 11 5 10 2 kyr b p in the gulf of cadiz 10 9 kyr b p in the alboran sea and 8 9 8 4 kyr b p in the thyrrenian sea a general cooling trend from these sst maxima to present day is observed during this stage which is marked by short cooling oscillations with a periodicity of 730 40 years and its harmonics

late glacial early holocene slope deposits on the swiss plateau genesis and palaeo environment abstract on the swiss plateau glacial and glaciofluvial sediments deposited during mis 2 are widespread they are generally overlain by younger sediments of different origin mainly related to periglacial and slope wash processes depending on their genesis and composition 3 types of slope deposits can be distinguished which are classified as units 1 2a and 2b unit 1 is characterized by its wide spatial occurrence and a constant thickness of 40 60 cm high silt contents and a sharp lithological discontinuity to the lying sediments generally forming the parent material for the ah and al horizons of the luvisols unit 2 represents erosion rills filled up with loess loam and some gravel based on stratigraphic assumptions the formation of unit 1 has been tentatively attributed to the younger dryas optical stimulated luminescence and radiocarbon dating of unit 2 indicate morphodynamic activity during the early holocene up to 7 5 ka suggesting an open landscape this scenario is in conflict with the established notion that reforestation in middle europe took place during the bolling allerod warm period in order to explain this apparent contradiction for the younger dryas to early holocene environment we suggest a continental climate with dry summers and drought stress on the vegetation in combination with very cold winters and deep soil frost at the pleistocene holocene transition caused by the orbital precession maximum after 7 5 ka with the spread of oceanic woodland and reduced seasonal contrasts the landscape stabilized and soils developed

southward migration of the intertropical convergence zone through the holocene titanium and iron concentration data from the anoxic cariaco basin off the venezuelan coast can be used to infer variations in the hydrological cycle over northern south america during the past 14 000 years with subdecadal resolution following a dry younger dryas a period of increased precipitation and riverine discharge occurred during the holocene thermal maximum since approximately 5400 years ago a trend toward drier conditions is evident from the data with high amplitude fluctuations and precipitation minima during the time interval 3800 to 2800 years ago and during the little ice age these regional changes in precipitation are best explained by shifts in the mean latitude of the atlantic intertropical convergence zone itcz potentially driven by pacific based climate variability the cariaco basin record exhibits strong correlations with climate records from distant regions including the high latitude northern hemisphere providing evidence for global teleconnections among regional climates

a high resolution absolute dated holocene and deglacial asian monsoon record from dongge cave china abstract we present a continuous record of the asian monsoon over the last 16 ka from 18o measurements of stalagmite calcite over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230th dates 18o and therefore asian monsoon intensity generally follows changes in insolation although changes in 18o are generally accommodated in abrupt shifts in contrast to smoothly varying insolation indicating that threshold effects may be important 18o decreased dramatically 3 at the start of the holocene 11 5 ka and remained low for 6 ka four positive 18o events centered at 11225 97 yr bp 1 05 10880 117 yr bp 1 15 9165 75 yr bp 1 4 and a double event centered at 8260 64 yr bp 1 1 and 8080 74 yr bp 1 0 punctuated this period of high monsoon intensity all four events correlate within error with climate changes in greenland ice cores thus the relationship between the asian monsoon and the north atlantic observed during the glacial period appears to continue into the early holocene in addition three of the four events correlate within error with outburst events from lake agassiz the decline of monsoon intensity in the mid late holocene is characterized by an abrupt positive shift in 18o which occurs at 3550 59 yr bp 1 1 in 100 yr in addition the holocene is punctuated by numerous centennial and multi decadal scale events amplitudes 0 5 to 1 up to half the amplitude of the glacial interstadial events seen in the last glacial period thus holocene centennial and multi decadal scale monsoon variability is significant although not as large as glacial millennial scale variability the monsoon shows a strong connection with northern south american hydrological changes related by changes in itcz position spectral analysis of the 18o record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing however there are numerous other significant peaks including peaks at el nino frequencies observed for high resolution portions of the record between 8110 and 8250 yr which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling holocene monsoon climate in addition for this high resolution portion we observe a distinctive biennial oscillation of the asian monsoon which has been associated with the tropospheric biennial oscillation tbo

mollusca stable isotope record of a core from lake frassino northern italy hydrological and climatic changes during the last 14 ka a core retrieved from lake frassino northern italy provided evidence of palaeohydrological change in this area during the last 14 ka lithological malacological and in particular stable isotope composition of freshwater shells allowed the delineation of the main phases of lake evolution between the lateglacial and holocene lateglacial conditions were drier than the holocene although a wetter period was inferred before c 14 ka according to the oxygen isotope composition of freshwater shells the holocene showed a clear bipartition the first part which lasted from 9100 to 7000 yr bp was drier and was followed by a rapid increase in humidity at 7000 6800 yr bp between 6800 and 5000 yr bp there were wetter and more stable conditions as indicated by smaller 18 o oscillations of pisidium and valvata shells from c 5000 to 2600 yr bp the record is characterized by larger fluctuations which may indicate that short term and particularly pronounced alternation of wet and dry periods occurred

high resolution sediment and vegetation responses to younger dryas climate change in varved lake sediments from meerfelder maar germany abstract this work focuses on a 1900 year section of varved sediments from lake meerfelder maar mfm extending from the late allerod to the preboreal varve counting provides the chronological framework and determines the length of younger dryas to 1025 1090 years a strong relation between climate change environment response and depositional processes has been found in consequence varve microfacies variations are a sensitive proxy for environment changes these are reflected for example in erosion processes within the lake s catchment minerogenic input and lake productivity diatom blooms the observed varve changes have been quantified by multiproxy analyses of physical and chemical sediment parameters with a resolution of between 8 and 40 years depending on sedimentation rate in addition high resolution palynological investigations provide the biostratigraphical subdivision based on changes in the vegetation occurring during the same time interval varve observations reveal that environment changes at the beginning and the end of the younger dryas occurred within 20 50 years furthermore sediment and vegetation changes were synchronous within the actual precision of the mfm and grip chronologies divergence of only a few decades terrestrial responses in western europe occurred quasi synchronous to temperature changes in greenland

holocene flood frequency across the central alps solar forcing and evidence for variations in north atlantic atmospheric circulation the frequency of large scale heavy precipitation events in the european alps is expected to undergo substantial changes with current climate change hence knowledge about the past natural variability of floods caused by heavy precipitation constitutes important input for climate projections we present a comprehensive holocene 10 000 years reconstruction of the flood frequency in the central european alps combining 15 lacustrine sediment records these records provide an extensive catalog of flood deposits which were generated by flood induced underflows delivering terrestrial material to the lake floors the multi archive approach allows suppressing local weather patterns such as thunderstorms from the obtained climate signal we reconstructed mainly late spring to fall events since ice cover and precipitation in form of snow in winter at high altitude study sites do inhibit the generation of flood layers we found that flood frequency was higher during cool periods coinciding with lows in solar activity in addition flood occurrence shows periodicities that are also observed in reconstructions of solar activity from 14 c and 10 be records 2500 3000 900 1200 as well as of about 710 500 350 208 suess cycle 150 104 and 87 gleissberg cycle years as atmospheric mechanism we propose an expansion shrinking of the hadley cell with increasing decreasing air temperature causing dry wet conditions in central europe during phases of high low solar activity furthermore differences between the flood patterns from the northern alps and the southern alps indicate changes in north atlantic circulation enhanced flood occurrence in the south compared to the north suggests a pronounced southward position of the westerlies and or blocking over the northern north atlantic hence resembling a negative nao state most distinct from 4 2 to 2 4 kyr bp and during the little ice age south alpine flood activity therefore provides a qualitative record of variations in a paleo nao pattern during the holocene additionally increased south alpine flood activity contrasts to low precipitation in tropical central america cariaco basin on the holocene and centennial time scale this observation is consistent with a holocene southward migration of the atlantic circulation system and hence of the itcz driven by decreasing summer insolation in the northern hemisphere as well as with shorter term fluctuations probably driven by solar activity

molecular proxies for paleoclimatology we summarize the applications of molecular proxies in paleoclimatology marine molecular records especially are proving to be of value but certain environmentally persistent compounds can also be measured in lake sediments loess deposits and ice cores the fundamentals of this approach are the molecular parameters the compound abundances and carbon hydrogen nitrogen and oxygen isotopic contents which can be derived by the analysis of sediment extracts these afford proxy measures which can be interpreted in terms of the conditions which control climate and also reflect its operation we discuss two types of proxy those of terrigenous and those of aquatic origin and exemplify their application in the study of marine sediments through the medium of ten case studies based in the atlantic mediterranean and pacific oceans and in antarctica the studies are mainly for periods in the present the holocene and particularly the last glacial interglacial but they also include one study from the cretaceous the terrigenous proxies which are measures of continental vegetation are based on higher plant leaf wax compounds i e long chain circa c30 hydrocarbons alcohols and acids they register the relative contributions of c3 vs c4 type plants to the vegetation in the source areas the two marine proxies are measures of sea surface temperatures sst the longer established one u37k is based on the relative abundances of c37 alkenones photosynthesized by unicellular algae members of the haptophyta the newest proxy tex86 is based on c86 glycerol tetraethers gdgts synthesized in the water column by some of the archaeal microbiota the crenarchaeota

an abrupt wind shift in western europe at the onset of the younger dryas cold period the younger dryas cold reversal during the last glacial termination is one of the most abrupt climate change events observed in the northern hemisphere analyses of varved lake sediments from western germany suggest that storminess in the north atlantic region increased within a single year at this time providing a mechanistic link between a decrease in the meridional overturning circulation and western european cooling the younger dryas cooling 12 700 years ago is one of the most abrupt climate changes observed in northern hemisphere palaeoclimate records1 2 3 4 annually laminated lake sediments are ideally suited to record the dynamics of such abrupt changes as the seasonal deposition responds immediately to climate and the varve counts provide an accurate estimate of the timing of the change here we present sub annual records of varve microfacies and geochemistry from lake meerfelder maar in western germany providing one of the best dated records of this climate transition5 our data indicate an abrupt increase in storminess during the autumn to spring seasons occurring from one year to the next at 12 679 yr bp broadly coincident with other changes in this region we suggest that this shift in wind strength represents an abrupt change in the north atlantic westerlies towards a stronger and more zonal jet changes in meridional overturning circulation alone cannot fully explain the changes in european climate6 7 we suggest the observed wind shift provides the mechanism for the strong temporal link between north atlantic ocean overturning circulation and european climate during deglaciation

late glacial and holocene history of the northeast mediterranean mountain glaciers new insights from in situ produced 36cl based cosmic ray exposure dating of paleo glacier deposits on mount olympus greece in this study we present a new glacial chronology based on 20 in situ produced 36cl based cosmic ray exposure datings from moraine boulders and bedrock from the throne of zeus tz and megala kazania mk cirques on mount olympus the 36cl derived ages of glacial landforms range from 15 6 2 0 to 0 64 0 08 ka spanning the late glacial and the holocene the late glacial recorded in both cirques is partitioned in three distinct phases lg1 3 an initial phase of moraine stabilization at 15 5 2 0 ka with subsequent deglaciation starting at 14 ka lg1 followed by a shift to marginal conditions for glaciation at 13 5 2 0 ka lg2 sustained by large amounts of wind blown snow despite regional warming glacial conditions returned at 12 5 1 5 ka lg3 and were characterized by low air temperatures and glacier shrinking the holocene glacial phases hol1 3 are recorded only in the mk cirque likely due to its topographic attributes an early holocene glacier stillstand hol1 at 9 6 1 1 ka follows the regional temperatures recovery no glacier activity is observed during the mid holocene the late holocene glacier expansions include a moraine stabilization phase hol2 at 2 5 0 3 ka during wet conditions and solar insolation minima while hol3 corresponds to the early part of the little ice age 0 64 0 08ka our glacial chronology is coherent with glacial chronologies from several cirques along the northeast mediterranean mountains and in pace with numerous proxies from terrestrial and marine systems from the north aegean sea

assessment of rock mass strength for underground excavations abstract when the stability of underground openings is assessed one must concern with local and global failure modes local failures may take place as long as rock blocks are kinematically movable into openings while global failure modes are associated with the stress state and the strength of rock mass surrounding openings this fact is always confused in underground rock engineering first the authors briefly describe several approaches how to assess the strength of rock masses together with some new proposals for underground excavations then the estimations by these methods are compared with each other as well as with experimental data finally the validity of these methods are discussed and some recommendations are made for practical applications

the role of seasonality in abrupt climate change abstract a case is made that seasonality switches dominated by wintertime were instrumental in abrupt climate changes in the north atlantic region during the last glaciation and into the holocene the primary evidence comes from mismatches between mean annual temperatures from greenland ice cores in comparison with snowline changes in east greenland northern europe and north america the most likely explanation is a shutdown or reduction in strength of the conveyor this allows the spread of winter sea ice across the north atlantic thus causing the northern region to experience much colder winters because they mimic the greenland temperature rather than the snowline signal changes in the atlantic intertropical convergence zone and the asian monsoon may also share a winter linkage with greenland thus the paleoclimate record is consistent with the notion that a huge continental sector of the northern hemisphere stretching from greenland to asia was close to an extreme winter threshold during much of the last glaciation winter climate crossed this threshold repeatedly with marked changes in seasonality that may well have amplified and propagated a signal of abrupt change throughout the hemisphere and into the tropics

empirical rock mechanical site descriptive modeling rmsdm for the korea atomic energy research institute underground research tunnel kurt as part of master plan when preparing to construct the second stage of the korea atomic energy research institute underground research tunnel kurt 2 site investigations were carried out to characterize the rock mass and its related geophysical nature the rock mass at the study site was divided into rock units depending on a rock type and fracture developments in rock the rock mass quality for each rock unit was evaluated using rock mass classification systems such as q rock mass rating rmr and rock mass index rmi the mechanical properties of rock units were empirically estimated with associated rock mass classification systems including deformation modulus uniaxial compressive strength and cohesion and friction angles ultimately a rock mechanical site descriptive model rmsdm covering the block size of 85 m 120 m 80 m was developed by combining the analysis of rock units rock block consists of granite dike and fault being divided into six rock units such as g1 g2 g3 d1 d3 and f3 g1 and d1 rock units were classified as good rock masses and the rock mass quality of g2 is fair g3 and d3 rock units were classified as poor rock masses and the f3 rock unit was very poor the mechanical properties of rock unit g1 and d1 were almost considered similar and best and those of g2 were considered middle class g3 and d3 rock units had poor mechanical properties and those of f3 were the worst g1 occupies most of block volume but other rock units were distributed as small portions two dimensional distributions of rock mass from modeling and face mapping at the elevation of the tunnel excavation exhibited that predicted distributions well fit to those observed therefore rmsdm will be of help with the geoscientific understanding of site investigation and designing of a site and construction of a site similar to kurt 2 and ultimately it will become a scientific base to future related research and development projects of the korea atomic energy research institute kaeri