revised calendar date for the taupo eruption derived by 14c wiggle matching using a new zealand kauri 14c calibration data set taupo volcano in central north island new zealand is the most frequently active and productive rhyolite volcano on earth its latest explosive activity about 1800 years ago generated the spectacu

ice record of a large eruption of deception island volcano antarctica in the xviith century a well marked volcanic ash layer was found at 145 9 m depth in a 154 3 m ice core recovered in 1981 on james ross island antarctic peninsula ash composition analysis indicates that we are dealing with an eruption of the deception island volcano located some 200 km northwestward from james ross island regional lake sediments seem also to have recorded the eruption its date some 350 years ago has been determined precisely by comparison with a well dated south pole station ice core the strength and regional to global impact of the event are discussed it is concluded it was most probably the largest eruption of this volcano over the studied time period this exceptional layer was used to adjust the dating of the core

cold decade ad 1810 1819 caused by tambora 1815 and another 1809 stratospheric volcanic eruption climate records indicate that the decade of ad 1810 1819 including the year without a summer 1816 is probably the coldest during the past 500 years or longer and the cause of the climatic extreme has been attributed primarily to the 1815 cataclysmic tambora eruption in indonesia but the cold temperatures in the early part of the decade and the timing of the tambora eruption call into question the real climatic impact of volcanic eruptions here we present new evidence based on sulfur isotope anomaly 33s a unique indicator of volcanic sulfuric acid produced in the stratosphere and preserved in polar snow and on the precise timing of the volcanic deposition in both polar regions that another large eruption in 1809 of a volcano is also stratospheric and occurred in the tropics the tambora eruption and the undocumented 1809 eruption are together responsible for the unusually cold decade

inter hemispheric transport of volcanic ash from a 1259 a d volcanic eruption to the greenland and antarctic ice sheets a strong volcanic sulfuric acid signal corresponding to an age of 1259 a d has been reported in ice cores from greenland antarctica and arctic canada tiny 5 m volcanic glass shards were reported previously in samples from this layer in an ice core from the south pole here we report the discovery of volcanic glass shards from a contemporaneous layer in an ice core from summit greenland the major element composition of the glass shards in the greenland sample are identical to those from the south pole confirming the assumption that has been made previously that the sulfuric acid signal in the ice cores is an inter hemispheric time stratigraphic marker the composition of these glass shards is similar to those produced by a 550 700 yrs b p eruption of el chichon volcano in mexico suggesting that it may be the source of the widely dispersed material

a continuous 770 year record of volcanic activity from east antarctica a 100 m ice core from site g 15 accumulation rate 0 1 m water yr 1 mean annual temperature 38 c on the mizuho plateau dronning maud land east antarctica has been analysed using the dielectric profiling dep technique the capacitance and conductance of the core were measured at ac frequencies 20 hz 300 khz the high frequency conductivity profile shows variations that are primarily related to the strong acids derived from volcanic activity the tambora 1815 eruption can be identified with the aid of an approximate chronology based on the firn densification rate other historic eruptions can then be recognised beyond about 300 years historical observations are very few however if a constant overall accumulation rate is assumed a well known eruption of 1259 a d can be found near the bottom of the core other peaks in the conductivity profile can then be assigned dates accurate to within a few years using the conductivity profile it is possible to estimate the relative acid deposition fluxes produced by the main eruptions with reasonable accuracy the estimated acid deposisition fluxes realtive to the tambora 1815 eruption of agung 1963 is 27 krakatoa 1883 25 the signal of 1601 28 and that of 1259 53

temporal and spatial variability of surface mass balance at dome fuji east antarctica by the stake method from 1995 to 2006 the surface mass balance smb at dome fuji east antarctica was estimated using 36 bamboo stakes grid of 6 6 placed at 20 m intervals from 1995 to 2006 the heights of the stake tops from the snow surface were measured at 0 5 cm resolution twice monthly in 1995 1996 1997 and 2003 and once a year for the rest of the study period to account for snow settling the average snow density at the stake base during the measurements was used for converting the stake height data to smb the annual smb from 1995 to 2006 at dome fuji was 27 3 1 5 kg m 2 a 1 this result agrees well with the annual smb from ad 1260 to 1993 26 4 kg m 2 a 1 estimated from volcanic signals in the dome fuji ice core over the period 1995 2006 there were 37 8 6 of the measurements negative or zero annual smb results variation in the multi year averages of annual smb decreased with the square root of the number of observation years and 10 years of observations of a single stake allowed the estimation of annual smb at 10 accuracy the frequency distributions of annual and monthly smb were examined the findings clarify the complex behavior of the annual and monthly smb at dome fuji which will be common phenomena in areas of low snow accumulation of the interior of the antarctic ice sheet

uv induced mass independent sulfur isotope fractionation in stratospheric volcanic sulfate 1 sulfuric acid aerosols produced in the stratosphere following massive volcanic eruptions possess a mass independent sulfur isotopic signature acquired when volcanic so2 experiences uv photooxidation the volcanic data are consistent with laboratory so2 photooxidation experiments using uv light at 248 nm maximum absorption of ozone whereas sulfur isotopic anomalies previously observed in archean samples are consistent with photodissociation at 190 220 nm a mechanism of so2 photooxidation occurring in the early stage of a stratospheric volcanic plume in the range of 220 320 nm weak band absorption of so2 is also proposed since mass independent sulfur isotope anomalies in stratospheric volcanic sulfate appear to depend on the exposure of so2 to uv radiation their measurements might therefore offer the possibility to determine the degree of uv penetration in the ozone absorption window for the present and past atmospheres they can also be used to determine the stratospheric or tropospheric nature of volcanic eruptions preserved in glaciological records offering the possibility to reassess the climatic impact of past volcanic eruptions

sulfur budget and global climate impact of the a d 1835 eruption of cosiguina volcano nicaragua large explosive volcanic eruptions can inject massive amounts of sulfuric gases into the earth s atmosphere and in so doing affect global climate the january 1835 eruption of cosiguina volcano nicaragua ranks among the americas largest and most explosive historical eruptions but whether it had effects on global climate remains ambiguous new petrologic analyses of the cosiguina deposits reveal that the eruption released enough sulfur to explain a prominent ca ad 1835 sulfate anomaly in ice cores from both the arctic and antarctic a compilation of temperature sensitive tree ring chronologies indicates appreciable cooling of the earth s surface in response to the eruption consistent with instrumental temperature records we conclude that this eruption represents one of the most important sulfur producing events of the last few centuries and had a sizable climate impact rivaling that of the 1991 eruption of mount pinatubo

a 220 year continuous record of volcanic h2so4 in the antarctic ice sheet continuous h2so4 profiles observed in snow from several antarctic locations reveal four major volcanic events of the past two centuries agung krakatoa tambora and another large scale event not recorded historically acid deposition and interhemispheric distribution mechanisms are quantified and then used to obtain an order of magnitude estimate for the h2so4 emissions from these eruptions

volcanic sulfate deposition to greenland and antarctica a modeling sensitivity study reconstructions of the atmospheric sulfate aerosol burdens resulting from past volcanic eruptions are based on ice core derived estimates of volcanic sulfate deposition and the assumption that the two quantities are directly proportional we test this assumption within simulations of tropical volcanic stratospheric sulfur injections with the maecham5 ham aerosol climate model an ensemble of 70 simulations is analyzed with so2 injections ranging from 8 5 to 700 tg with eruptions in january and july modeled sulfate deposition flux to antarctica shows excellent spatial correlation with ice core derived estimates for pinatubo and tambora although the comparison suggests the modeled flux to the ice sheets is 4 5 times too large we find that greenland and antarctic deposition efficiencies the ratio of sulfate flux to each ice sheet to the maximum hemispheric stratospheric sulfate aerosol burden vary as a function of the magnitude and season of stratospheric sulfur injection changes in simulated sulfate deposition for large so2 injections are connected to increases in aerosol particle size which impact aerosol sedimentation velocity and radiative properties the latter leading to strong dynamical changes including strengthening of the winter polar vortices which inhibits the transport of stratospheric aerosols to high latitudes the resulting relationship between antarctic and greenland volcanic sulfate deposition is nonlinear for very large eruptions with significantly less sulfate deposition to antarctica than to greenland these model results suggest that variability of deposition efficiency may be an important consideration in the interpretation of ice core sulfate signals for eruptions of tambora magnitude and larger

impact of the cerro hudson and pinatubo volcanic eruptions on the antarctic air and snow chemistry atmospheric records of sulfate and msa in aerosols were obtained by year round samplings in the boundary layer at two coastal antarctic sites neumayer 1983 1995 and dumont d urville 1991 1997 at dumont d urville and neumayer the non sea salt sulfate nssso42 level observed from october 1991 to october 1993 exceeded by 44 and 48 ng m 3 respectively the mean level 150 ng m 3 observed during nonvolcanic years the neumayer and dumont d urville records first exhibit spring october to december 1991 nssso42 concentrations exceeding mean spring concentrations by some 100 to 150 ng m 3 caused by a significant poleward transport of the cerro hudson volcanic aerosol in the lower stratosphere beneath the polar vortex and possibly in the middle upper troposphere limited to 10 ng m 3 during winter 1992 the nssso42 perturbation reached 78 ng m 3 in fall 1993 at neumayer the latter enhancement corresponds to the input of the pinatubo volcanic aerosol advected through stratosphere troposphere air mass exchanges an enhancement of nssso42 concentrations is also recorded in snow layers deposited between 1991 and 1993 at various sites located over the high antarctic plateau on the basis of these firn data the relative impact of the three latest volcanic eruptions of global concern namely mount agung 1963 el chichon 1982 and pinatubo together with cerro hudson 1991 was evaluated in terms of sulfate input at high southern latitudes the fallout of sulfate in central antarctic snow following the cerro hudson pinatubo eruptions was slightly lower than fallout after the mount agung eruption sulfate fallout after el chichon was 2 to 3 times lower than that from either mount agung or pinatubo the enhancement of sulfate levels detected in central antarctic snow deposits during the 1991 1993 time period allows us to estimate a mean atmospheric sulfate perturbation of around 60 ng m 3 in the boundary layer of these regions i e at least 35 higher than that seen at coastal sites this observation suggests that coastal antarctic regions are less sensitive than the high plateau in detecting volcanic sulfate fallouts following eruptions of global concern atmospheric near surface year round sampling achieved at coastal antarctic sites reveals no significant enhancement of the nitrate level over 1992 and 1993 suggesting that volcanic aerosols have had a limited effect on the transfer of nitric acid from the lower antarctic stratosphere to the boundary layer in these regions

sediments in palaeo notches potential proxy records for palaeoclimatic changes in antarctica abstract many climatic proxy materials such as ice cores coastal and lacustrine sediments and abandoned penguin rookeries have been used to study palaeoclimatic changes and the palaeoenvironmental evolution of antarctica in this paper we report another geological record well preserved sedimentary sequences in the palaeo notches in marine terraces of fildes peninsula king george island based upon grain size distribution and microtexture geochemical element compositions and radiocarbon dating we identified the sediments in one palaeo notch as lacustrine sediments most likely deposited in a small palaeo lake from these data we inferred that between 4000 and 3000 yr b p a moderate chemical weathering occurred and the climate was warmer and more humid than present in good agreement with the findings from other climatic proxy materials we believe that the sediments in palaeo notches provide another reliable proxy material for studying the palaeoclimate and the palaeoenvironment in antarctica

vegetation succession and climate change across the plio pleistocene transition in eastern azerbaijan central eurasia 2 77 2 45 ma abstract the plio pleistocene transition marked a key moment in global climate history characterised by the onset of major glaciations in the northern hemisphere the palaeoenvironmental history of the plio pleistocene transition is not well known for the caspian sea region despite its importance for global climate dynamics here we present an independently 40ar 39ar dated high resolution terrestrial palynological record spanning the plio pleistocene boundary based on a lacustrine marine sedimentary sequence from eastern azerbaijan despite complex pollen transport pathways and the proximity of closely stacked mountain vegetation belts in the greater and lesser caucasus the record shows that regional vegetation responded to milankovitch forced glacial interglacial cycles tentatively correlated with global climatic records spanning mis g8 to 98 2 77 2 45 ma the persistence of mesophilous forests during glacial times indicates that some settings in the south caspian basin acted as glacial refugia and that vegetation response to glaciations was muted by increased moisture availability linked to caspian transgression the palynological record shows a relationship with global 18o stacks and specifically to the obliquity record we anticipate that precise correlation with the global climatostratigraphic timescale will allow better understanding of the nature and timing of important transgressive events in the caspian sea and their relevance on a global scale

holocene volcanic history as recorded in the sulfate stratigraphy of the european project for ice coring in antarctica dome c edc96 ice core 1 a detailed history of holocene volcanism was reconstructed using the sulfate record of the european project for ice coring in antarctica dome c edc96 ice core this first complete holocene volcanic record from an antarctic core provides a reliable database to compare with long records from antarctic and greenland ice cores a threshold method based on statistical treatment of the lognormal sulfate flux distribution was used to differentiate volcanic sulfate spikes from sulfate background concentrations ninety six eruptions were identified in the edc96 ice core during the holocene with a mean of 7 9 events per millennium the frequency distribution events per millennium showed that the last 2000 years were a period of enhanced volcanic activity edc96 volcanic signatures for the last millennium are in good agreement with those recorded in other antarctic ice cores for older periods comparison is in some cases less reliable mainly because of dating uncertainties sulfate depositional fluxes of individual volcanic events vary greatly among the different cores a volcanic flux normalization volcanic flux tambora flux ratio was used to evaluate the relative intensity of the same event recorded at different sites in the last millennium normalized flux variability for the same event showed the highest value in the 1100 1500 ad period this pattern could mirror changes in regional transport linked to climatic variations such as slight warming stages in the southern hemisphere southern hemisphere medieval warming like period

volcanic forcing of climate over the past 1500 years an improved ice core based index for climate models 1 understanding natural causes of climate change is vital to evaluate the relative impacts of human pollution and land surface modification on climate we have investigated one of the most important natural causes of climate change volcanic eruptions by using 54 ice core records from both the arctic and antarctica our recently collected suite of ice core data more than double the number of cores ever used before reduces errors inherent in reconstructions based on a single or small number of cores which enables us to obtain much higher accuracy in both detection of events and quantification of the radiative effects we extracted volcanic deposition signals from each ice core record by applying a high pass loess filter to the time series and examining peaks that exceed twice the 31 year running median absolute deviation we then studied the spatial pattern of volcanic sulfate deposition on greenland and antarctica and combined this knowledge with a new understanding of stratospheric transport of volcanic aerosols to produce a forcing data set as a function of month latitude and altitude for the past 1500 years we estimated the uncertainties associated with the choice of volcanic signal extraction criteria ice core sulfate deposition to stratospheric loading calibration factor and the season for the eruptions without a recorded month we forced an energy balance climate model with this new volcanic forcing data set together with solar and anthropogenic forcing to simulate the large scale temperature response the results agree well with instrumental observations for the past 150 years and with proxy records for the entire period through better characterization of the natural causes of climate change this new data set will lead to improved prediction of anthropogenic impacts on climate the new data set of stratospheric sulfate injections from volcanic eruptions for the past 1500 years as a function of latitude altitude and month is available for download in a format suitable for forcing general circulation models of the climate system

evidence from sulfate mass independent oxygen isotopic compositions of dramatic changes in atmospheric oxidation following massive volcanic eruptions 1 oxygen isotopic ratio measurements 17o and 18o of background and volcanic sulfate preserved in south pole snow and ice were used to investigate the impact on the oxidation state of the atmosphere by explosive volcanic eruptions by comparing different paleovolcanic events we observe a difference in the so2 oxidation pathway between moderate tens of teragrams tg of so2 and massive hundreds of tg eruptions both isotopic data and numerical simulations suggest the shutdown of stratospheric oh chemistry and the opening of unaccounted oxidation channels for so2 such as the reaction with o 3p atoms when hundreds of tg of so2 are injected into the stratosphere it is very likely that oxidation rates and pathways and concentrations of most traces gases are also dramatically affected with potentially important implications for climate forcing

antarctic volcanic flux ratios from law dome ice cores 3 climatestudiescenter institutefor quaternarystudies universityofmaine orono me 04469 5717 u s a abstract explosivevolcanic eruptions can inject largequantitiesof sulphur dioxide intothe stratosphere theaerosolsthat result fromoxidationof thesulphur dioxidecanpro duce significant cooling of the troposphere by reflecting or absorbing solar radiation it is possibleto obtainanestimateoftherelativestratosphericsulphuraerosolconcentrationpro duced by different volcanoes by comparing sulphuric acid fluxes determined by analysis of polaricecores here weuseanon sea saltsulphatetimeseriesderivedfromthreewell dated law dome ice cores to investigate sulphuric acid flux ratios for major eruptions over the period ad1301 1995 weuseadditionaldata fromothercorestoinvestigatesystematicspa tial variability in the ratios only for the kuwae eruption law dome ice date ad1459 5 wasthe h2so4 flux largerthanthatdepositedbytambora law domeicedate ad1816 7

annually resolved southern hemisphere volcanic history from two antarctic ice cores the continuous sulfate analysis of two antarctic ice cores one from the antarctic peninsula region and one from west antarctica provides an annually resolved proxy history of southern semisphere volcanism since early in the 15th century the dating is accurate within 3 years due to the high rate of snow accumulation at both core sites and the small sample sizes used for analysis the two sulfate records are consistent with each other a systematic and objective method of separating outstanding sulfate events from the background sulfate flux is proposed and used to identify all volcanic signals the resulting volcanic chronology covering 1417 1989 a d resolves temporal ambiguities about several recently discovered events a number of previously unknown moderate eruptions during late 1600s are uncovered in this chronology the eruption of tambora 1815 and the recently discovered eruption of kuwae 1453 in the tropical south pacific injected the greatest amount of sulfur dioxide into the southern hemisphere stratosphere during the last half millennium a technique for comparing the magnitude of volcanic events preserved within different ice cores is developed using normalized sulfate flux for the same eruptions the variability of the volcanic sulfate flux between the cores is within 20 of the sulfate flux from the tambora eruption

reconstructing annual and seasonal climatic responses from volcanic events since a d 1270 as recorded in the deuterium signal from the greenland ice sheet project 2 ice core a 200 m ice core at the gisp 2 site summit greenland provides a 720 year record of volcanic eruptions identified by pronounced increases in so42 in relation to the background concentration deuterium hydrogen isotope ratios d measured in the same core provide a proxy climate record temperature used to examine the response of the climate system in greenland to these eruptions a group of 34 known volcanic events and a subgroup of the six largest volcanic events are isolated and examined for both groups significant negative cooler isotopic excursions occur beginning the year the volcanic event is detected in the ice core cooling is significant for 1 to 2 years the maximum isotopic excursion averages 4 0 7 c for all 34 events and 10 1 8 c for the subgroup of largest events for individual events the response in the isotope signal to volcanic events is highly variable but occurs at most 1 year before so42 is detected in the core examination of subannual isotope data suggests that peak winter isotope values are lowered more than peak summer values we hypothesize that this result is flawed by posted positional alteration of the isotopic profile by vapor diffusion to test this hypothesis we use numerical deconvolution to account for the smoothing effects of vapor diffusion in the firn analysis of the deconvolved data shows greater summer than winter cooling a result more consistent with instrumental temperature data

late 20th century increase in south pole snow accumulation a compilation of the 37 year history of net accumulation at the south pole mosley thompson et al 1995 suggests an increase in net annual accumulation since 1965 this record is sporadic and its quality is compromised by spatially restricted observations and nonsystematic measurement procedures results from a new spatially extensive network of 236 accumulation poles document that the current 5 year 1992 1997 average annual net accumulation at the south pole is 84 5 8 9 mm water equivalent w e this accumulation rate reflects a 30 increase since the 1960s when the best although not optimal records indicate that it was 65 mm w e identification of two prominent beta radioactivity horizons 1954 1955 and 1964 1965 in six firn cores confirms an increase in accumulation since 1965 viewed from a longer perspective of accumulation provided by ice cores and a snow mine study the net accumulation of the 30 year period 1965 1994 is the highest 30 year average of this millennium limited data suggest this recent accumulation increase extends beyond the south pole region and may be characteristic of the high east antarctic plateau enhanced accumulation over the polar ice sheets has been identified as a potential early indicator of warmer sea surface temperatures and may offset a portion of the current rise in global sea level

the little ice age as recorded in the stratigraphy of the tropical quelccaya ice cap the analyses of two ice cores from a southern tropical ice cap provide a record of climatic conditions over 1000 years for a region where other proxy records are nearly absent annual variations in visible dust layers oxygen isotopes microparticle concentrations conductivity and identification of the historical a d 1600 huaynaputina ash permit accurate dating and time scale verification the fact that the little ice age about a d 1500 to 1900 stands out as a significant climatic event in the oxygen isotope and electrical conductivity records confirms the worldwide character of this event

record of volcanism since 7000 b c from the gisp2 greenland ice core and implications for the volcano climate system sulfate concentrations from continuous biyearly sampling of the gisp2 greenland ice core provide a record of potential climate forcing volcanism since 7000 b c although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions only about 30 percent of the events from 1 to 7000 b c were matched to such events several historic eruptions may have been greater sulfur producers than previously thought there are three times as many events from 5000 to 7000 b c as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions this increased volcanism in the early holocene may have contributed to climatic cooling

dating of two nearby ice cores from the illimani bolivia 1 in order to establish a chronology of two nearby ice cores from a glacier at illimani 6438 m bolivia a broad dating approach is presented here which in particular makes use of the fast simple and nearly nondestructive electrical conductivity method ecm that provides a highly resolved record thus ecm is suited for counting annual layers in the ice especially for ice cores extracted from high mountain glaciers with a fast layer thinning furthermore ecm can be used for detecting volcanic signals annual signals in the ecm record of the illimani ice core were identified using the 1964 a d tritium reference horizon and were counted along 125 m or 90 of the core representing the time period from 1200 240 a d estimated accumulated error to 1999 a d the resulting age depth relationship was supported by counting annual peaks in the microparticle record as well as by nuclear dating using the decay of 210pb the identification of volcanic signals originating from eruptions such as pinatubo 1991 a d el chichon 1982 a d agung 1963 a d krakatoa 1883 a d tambora 1815 a d and the unknown 1258 a d significantly reduced the uncertainty of annual layer counting alc to 2 years in the vicinity of these events

volcanic aerosol records and tephrochronology of the summit greenland ice cores the recently collected greenland ice sheet project 2 gisp2 and greenland ice core project ice cores from summit greenland provide lengthy and highly resolved records of the deposition of both the aerosol h2so4 and silicate tephra components of past volcanism both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism climate system the continuous time series of volcanic so42 for the last 110 000 years show a strong relationship between periods of increased volcanism and periods of climatic change the greatest number of volcanic so42 signals many of very high magnitude occur during and after the final stages of deglaciation 6000 17 000 years ago possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins sea level change the increase in the number of volcanic so42 signals at 27 000 36 000 and 79 000 85 000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation respectively a comparison of the electrical conductivity of the gisp2 core with that of the volcanic so42 record for the holocene indicates that only about half of the larger volcanic signals are coincident in the two records other volcanic acids besides h2so4 and other so42 sources can complicate the comparisons although the threshold level picked to make such comparisons is especially critical tephra has been found in both cores with a composition similar to that originating from the vatnaoldur eruption that produced the settlement layer in iceland mid a d 870s from the icelandic eruption that produced the saksunarvatn ash 10 300 years ago and from the icelandic eruption s that produced the z2 ash zone in north atlantic marine cores 52 700 years ago the presence of these layers provides absolute time lines for correlation between the two cores and for correlation with proxy records from marine sediment cores and terrestrial deposits containing these same tephras the presence of both rhyolitic and basaltic shards in the z2 ash in thegisp2 core and the composition of the basaltic grains lend support to multiple icelandic sources torfajokull area and katla for the z2 layer deposition of the z2 layer occurs at the beginning of a stadial event further reflecting the possibility of a volcanic triggering by the effects of changing climatic conditions

accumulation variability derived from an ice core from coastal dronning maud land antarctica a 100 m long ice core was retrieved from the coastal area of dronning maud land dml antarctica in the 2000 01 austral summer the core was dated to ad 1737 by identification of volcanic horizons in dielectrical profiling and electrical conductivity measurement records in combination with seasonal layer counting from high resolution oxygen isotope d 18 o data a mean long term accumulation rate of 0 29 m a 1 w e was derived from the high resolution d 18 o record as well as accumulation rates during periods in between the identified volcanic horizons a statistically significant decrease in accumulation was found from about 1920 to the present a comparison with other coastal ice cores from dml suggests that this is a regional pattern

ice cores as an index of global volcanism from 1850 to the present to evaluate an important cause of past climate change climate researchers need reliable estimates of volcanic aerosol loading in the atmosphere previous indices the dust veil index volcanic explosivity index and those by mitchell 1970 sato et al 1993 and khmelevtsov et al unpublished manuscript 1993 all have drawbacks ice core acidity and sulfate records because they contain physical evidence of atmospheric loading are a promising source of information on past volcanic aerosols but these records contain large nonvolcanic signals as well we have compared northern hemisphere nh and southern hemisphere sh annual average versions of five indices with eight nh and six sh ice core records for the period 1850 to the present in an attempt to identify the volcanic signal common to all records the indices are all highly correlated with each other for the nh although the individual ice core records are in general not well correlated with each other or with any of the indices a composite derived from averaging the cores the ice core volcano index ivi shows promise as a new index of volcanic aerosol loading this new index correlates well with the existing non ice core volcanic indices and with high frequency temperature records for the sh the individual ice cores and indices are better correlated the shivi is again highly correlated with all indices and individual ice cores but not with high frequency temperature records for both hemispheres the southern oscillation index shows no significant correlation with the volcanic indices ice cores or the ivi thus providing no evidence for the impact of volcanic eruptions on el nino southern oscillation events

sensitivity of chemical species to climatic changes in the last 45 kyr as revealed by high resolution dome c east antarctica ice core analysis

synchronous deposition of volcanic ash and sulfate aerosols over greenland in 1783 from the laki eruption iceland 1 sulfate aerosols from the 1783 1784 a d laki eruption are widely used as a reference horizon for constraining greenland ice core time scales yet the timing of the arrival of the sulfate remains under discussion two ice cores from western greenland analyzed with high temporal resolution confirm that sulfate aerosols arrived over greenland late in 1783 concomitant with the tephra elevated concentrations of cd bi and tl all indicators of volcanic emissions and with a short lived rare earth elements anomaly thereafter sulfate deposition declined rapidly very modest concentrations of sulfate in 1784 snowfall evident in six greenland cores suggest a relatively short less than 1 year atmospheric residence time and an injection height limited to the lower stratosphere an improved estimate of the associated stratospheric sulfate burden is calculated and provides an important input for models assessing climatic impacts of this volcanic eruption

a comparison of the volcanic records over the past 4000 years from the greenland ice core project and dye 3 greenland ice cores since 1980 the electrical conductivity method ecm has been used to infer volcanic acid signals in greenland ice cores the method reveals the great majority of major volcanic eruptions including several known from historic records subsequent ion chromatographic analyses of the acid volcanic layers show the chemical composition i e the concentration of the volcanic acids h2so4 hci and hf plus e g the nonvolcanically derived hno3 while ecm data are available from a large number of shallow depth greenland ice cores covering the past 500 1500 years only the greenland ice core project grip greenland ice sheet project 2 gisp2 and dye 3 deep ice cores exist for a detailed comparative study of volcanic signals in greenland ice cores representing several thousand years comparison of the volcanic signals registered in the grip and gisp2 cores will be presented elsewhere the latter cores were augered 30 km apart and essentially represent the same atmospheric conditions such as temperature snow accumulation and chemical composition of the air here we present a comparison between the major volcanic signals over the past 4000 years in the grip core from central greenland and the dye 3 core from se greenland in order to investigate the depositional differences many of the major signals are detected in both cores but some of the differences in the records can be used to infer the latitudinal band of some eruption sites furthermore the influence of the amount of annual precipitation and glaciological postdepositional processes on the volcanic signals is discussed

a 10 century comparison of prominent bipolar volcanic events in ice cores measurements of key chemical and physical parameters made along continuous and selected long sections of polar ice cores provide reliable past snow accumulation rates and other environmental records the prime accumulation indicators include variations found in the stable isotopes ionic constituents and acidity concentration levels and physical changes in the strata and structure cross correlations of the time series curves resulting from multiparameter analyses of ice cores from antarctica nby89 sp78 bs68 and greenland cr74 d3 81 d3 18c have been made the results permit construction of a bipolar chemical stratigraphy chronology of volcanic events that is coherent with the 18 o and electrical conductivity method data sets and consistent back in time with historically recorded volcanic activity a bihemispheric comparison of high non sea salt so 4 2 peaks shows strong correlation at 1885 1836 1816 1810 1459 1346 1287 1278 1259 1228 and 1168 a d at time of snow deposit the prominent 1259 a d volcanic signal appears to be a significant bipolar ice core index horizon

rare earth elements as reactive tracers of biogeochemical weathering in forested rhyolitic terrain article rareearthelements rees were evaluatedaspotentialtracers of biogeochemicalweathering atpedon hillslope and catchment scales in the jemez river basin critical zone observatory jrb czo valles caldera national pre serve nm usa we investigated time series of ree patterns in precipitation soil pore water groundwater and stream water and related these data to ree composition of soil rock and atmospheric dust ree signatures in stream waters are dynamic reflecting processes that occur along hydrologic flowpaths during transport to the stream including organic matter complexation primary and secondary mineral weathering water soil bedrock interaction and atmospheric deposition strong compositional similarities for the ree between soil waters and stream waters during the initial snowmelt are consistent with shallow subsurface flows to streams most bio

volcanic deposits in antarctic snow and ice major volcanic eruptions are able to spread large amounts of sulfuric acid all over the world acid layers of volcanic origin were detected for the first time a few years ago by hammer in greenland ice the present paper deals with volcanic deposits in the antarctic the different methods that can be used to find volcanic acid deposits in snow and ice cores are compared electrical conductivity sulfate and acidity measurements numerous snow and ice samples collected at several antarctic locations were analyzed the results reveal that the two major volcanic events recorded by h2so4 fallout in antarctic ice over the last century are the eruptions of krakatoa 1883 and agung 1963 both located at equatorial latitudes in the southern hemisphere the volcanic signals are found to be particularly well defined at central antarctic locations apparently in relation to the low snow accumulation rates in these areas it is demonstrated that volcanic sulfuric acid in snow is not even partially neutralized by ammonia the possible influence of antarctic volcanic activity on snow chemistry is also discussed using the three recent eruptions of the deception island volcano as examples only one of them seems to have had a significant effect on the chemistry of snow at a location 200 km from this volcano it is concluded that antarctic volcanic ice records are less complicated than greenland records because of the limited number of volcanos in the southern hemisphere and the apparently higher signal to background ratio for acidity in antarctica than in greenland

use of paleo records in determining variability within the volcanism climate system abstract volcanic eruptions that inject large quantities of sulfur rich gases into the stratosphere have the capability of cooling global climate by 0 2 0 3 c for several years after the eruption equatorial eruptions will impact global climate whereas mid latitude eruptions can cool climate in the hemisphere of origin magnitude of cooling varies by latitude and it is possible for warming to occur in certain regions primarily during the winter although instrumental records have been used to quantify the volcanic impact on climate they are limited in their temporal and spatial coverage and the style and magnitude of eruptions occurring over the two centuries of instrumental records is limited a thorough evaluation of the range of variability in the volcanism climate system requires a multidisciplinary approach that includes the analysis of ice core records geological data atmospheric measurements and visual phenomena tree ring records and other proxy data evaluation of these longer time series indicates that multiple volcanic eruptions have the potential to force climate over decadal to multi decadal time frames especially when these eruptions enhance or extend pre existing cool conditions on the other hand a lack of climatically significant eruptions may result in warmer average temperatures over decadal time frames because the volcanic cooling component within the climate system is absent mega eruptions like the toba eruption of 71 000 73 000 yr ago may impact climate on centennial time frames through positive feedback mechanisms evidence exists which indicates that environmental changes associated with rapid climatic fluctuations such as crustal loading unloading with glaciation deglaciation and variability in glacial meltwater loading on ocean basins may cause an increase in volcanic activity

eight centuries of volcanic signal and climate change at talos dome east antarctica 1 during the 1996 programma nazionale di ricerche in antartide international trans antarctic scientific expedition traverse two firn cores were retrieved from the talos dome area east antarctica at elevations of 2316 m td 89 m long and 2246 m st556 19 m long cores were dated by using seasonal variations in non sea salt nss so42 concentrations coupled with the recognition of tritium marker level 1965 1966 and nss so42 spikes due to the most important volcanic events in the past pinatubo 1991 agung 1963 krakatoa 1883 tambora 1815 kuwae 1452 unknown 1259 the number of annual layers recognized in the td and st556 cores was 779 and 97 respectively the d record obtained from the td core has been compared with other east antarctic isotope ice core records dome c epica south pole taylor dome these records suggest cooler climate conditions between the middle of 16th and the beginning of 19th centuries which might be related to the little ice age lia cold period because of the high degree of geographical variability the strongest lia cooling was not temporally synchronous over east antarctica and the analyzed records do not provide a coherent picture for east antarctica the accumulation rate record presented for the td core shows a decrease during part of the lia followed by an increment of about 11 in accumulation during the 20th century at the st556 site the accumulation rate observed during the 20th century was quite stable

an inter hemispheric volcanic time marker in ice cores from greenland and antarctica a strong volcanic acid signal is clearly registered using an acidity measuring technique in the a d 1259 ice layer in four different greenland ice cores camp century milcent crete and dye 3 this signal is similar in amplitude to the laki iceland a d 1783 volcanic event as recorded in the central and south greenland ice cores measurement of ice layers from corresponding age levels in antarctic ice cores byrd station south pole and j 9 on the ross ice shelf provides similar strong acid signals there is no historical record of a significant volcanic eruption for the period around a d 1260 in the northern hemisphere subsequent chemical analyses of all a d 1259 ice layers show similar compositions we suggest that the a d 1259 signals registered in both greenland and antarctica were caused by the same volcanic disturbance and that its epicenter was located at the earth s equatorial zone which enabled global distribution of the acid gases these results indicate that inter hemispheric dating of ice sheets is possible by the chemical identification of major eruptive volcanic events in the equatorial zone

ground based measurements of spatial and temporal variability of snow accumulation in east antarctica the east antarctic ice sheet is the largest highest coldest driest and windiest ice sheet on earth understanding of the surface mass balance smb of antarctica is necessary to determine the present state of the ice sheet to make predictions of its potential contribution to sea level rise and to determine its past history for paleoclimatic reconstructions however smb values are poorly known because of logistic constraints in extreme polar environments and they represent one of the biggest challenges of antarctic science snow accumulation is the most important parameter for the smb of ice sheets smb varies on a number of scales from small scale features sastrugi to ice sheet scale smb patterns determined mainly by temperature elevation distance from the coast and wind driven processes in situ measurements of smb are performed at single points by stakes ultrasonic sounders snow pits and firn and ice cores and laterally by continuous measurements using ground penetrating radar smb for large regions can only be achieved practically by using remote sensing and or numerical climate modeling however these techniques rely on ground truthing to improve the resolution and accuracy the separation of spatial and temporal variations of smb in transient regimes is necessary for accurate interpretation of ice core records in this review we provide an overview of the various measurement techniques related difficulties and limitations of data interpretation describe spatial characteristics of east antarctic smb and issues related to the spatial and temporal representativity of measurements and provide recommendations on how to perform in situ measurements

the pinatubo eruption in south pole snow and its potential value to ice core paleovolcanic records snow samples collected in the 1996 austral summer at south pole show that sulfate concentrations in snow and by inference sulfur aerosol concentrations in the antarctic atmosphere were elevated from the end of 1991 to mid 1994 over a stable non volcanic background the new data support earlier findings that the june 1991 pinatubo eruption and the hudson eruption in the same year deposited volcanic sulfate and tephra in south pole snow and provide strong evidence of the global distribution of volcanic materials from the pinatubo eruption in this study snow samples were taken in six snow pits spatially distributed around the south pole station in order to evaluate the local spatial variability of volcanic signals due to glaciological variables such as snow accumulation rates and snow redistribution by wind after initial deposition the results indicate that pinatubo sulfate flux varies by as much as 20 throughout a 400 km2 area centered around the south pole station this glaciological variability probably represents the likely range of volcanic signals due to variations in snow deposition and post depositional changes the pinatubo eruption provides an unprecedented opportunity to estimate aerosol mass loadings by explosive volcanic eruptions found in antarctic ice cores via a quantitative relationship between aerosol mass loadings and sulfate flux in antarctic snow here the satellite estimated pinatubo so2 emission and the measured volcanic sulfate flux in snow with an assumed linearly quantitative relationship are used to calculate so2 loadings for several well known volcanic eruptions in the past 300 years covered by a shallow 42 m south pole firn core drilled in 1996 the errors for the calculated mass loadings are estimated by means of the glaciological variability associated with pinatubo volcanic flux

accumulation at south pole comparison of two 900 year records two 900 year records of annual accumulation at south pole are compared to evalu ate the origin and significance of observed variations despite difficulties establishing absolute timescales due to problems identifying annual layer markers the two records can be correlated with confidence after moderate smoothing this correlation shows that over the time period considered 1050 1956 a d no climatically significant changes in accumulation occurred in stead fluctuations preserved in the two cores reflect spatial variations in snow accumulation as sociated with nonuniform deposition induced by surface relief on the scale of several kilometers

the taupo eruption new zealand i general aspects the ca a d 186 taupo eruption was the latest eruption at the taupo volcanic centre occurring from a vent at horomatangi reefs now submerged beneath lake taupo in the central north island of new zealand minor initial phreatomagmatic activity was followed by the dry vent 6 km 3 hatepe plinian outburst large amounts of water then entered the vent during the 2 5 km 3 hatepe phreatoplinian ash phase eventually stopping the eruption though large amounts of water continued to be ejected from the vent area causing gullying of the ash deposits after a break of several hours to weeks phreatoplinian activity resumed generating the 1 3 km 3 rotongaio ash notable for its fine grainsize and for containing significant quantities of non or poorly vesicular juvenile material the vent area then became dry again and eruption rates and power markedly increased into the 23 km 3 taupo ultraplinian phase which is the most powerful plinian outburst yet documented synchronous with this ultraplinian activity lesser volumes of non to partially welded ignimbrite were generated by diversion of ejecta from or partial collapse of the eruption column the rapid rate of magma withdraw al during this phase removed support from the vent area to trigger local vent collapse and initiate the catastrophic eruption of the ca 30 km 3 taupo ignimbrite finally after some years lava was extruded on to the floor of the reformed lake taupo and floating fragments derived from the lava carapace were driven ashore the known eruption volume is more than 65 km 3 while additional volumes are represented by primary material now beneath lake taupo and layer 3 to the ignim brite phases a total volume of more than 105 km 3 is likely equivalent to more than 35 km 3 of magma plus more than 3 km 3 of lithic debris airfall deposits more than 10 cm thick blanketed 30000 km 2 of land east of the vent while ignimbrite covers a near circular area of 20000 km 2 widespread and locally severe ground shaking occurred during but mostly after the eruption associated with subsidence in the lake taupo basin secondary deposits are abundant above and extending beyond the taupo ignimbrite consisting of the products of surface water interacting with the still hot ignimbrite and subsequent water reworking of the light pumiceous materials the complexity and size of this eruption preclude accurate forecasting of the size nature and return period of the inevitable next eruption from the taupo volcanic centre

a 4100 year record of explosive volcanism from an east antarctica ice core extensive archives of volcanic history are available from ice cores recovered from the antarctic and greenland ice sheets that receive and preserve sulfuric acid fallout from explosive volcanic eruptions the continuous detailed average 1 2 samples per year sulfate measurements of a 200 m ice core from a remote east antarctica site plateau remote provide a record of southern hemisphere volcanism over the last 4100 years this extends the volcanic record beyond the last 1000 years covered by previous antarctic ice cores an average of 1 3 eruptions per century is recorded in east antarctic snow during the last 4100 years the record shows that on average eruptions have been more frequent and more explosive during the most recent 2000 years than in the previous 2100 years intervals up to 500 years are observed in which few explosive volcanic signals are detected these periods include 2000 1500 b c no eruptions 500 1 b c two eruptions and 700 1200 a d two eruptions this new plateau remote volcanic record is compared with those from previous antarctic ice cores covering the last 1000 years in terms of dates for volcanic events the new record is in excellent agreement with the earlier records however significant discrepancies are found between these records in relative signal magnitude volcanic flux of several well known events the discrepancies among the records may be explained by the differences in the glaciology at the ice core sites analytical techniques used for sulfate and sulfuric acid measurement and the selection of detection thresholds for volcanic signals comparison with greenland ice core volcanic records indicates that during the last millennium nine large low latitude eruptions contributed significant amounts of volcanic aerosols to the atmosphere of both hemispheres potentially affecting global climate in contrast only one or possibly two such eruptions are found in the first millennium a d

the 1452 or 1453 a d kuwae eruption signal derived from multiple ice core records greatest volcanic sulfate event of the past 700 years 1 we combined 33 ice core records 13 from the northern hemisphere and 20 from the southern hemisphere to determine the timing and magnitude of the great kuwae eruption in the mid 15th century we extracted volcanic deposition signals by applying a high pass loess filter to the time series and examining peaks that exceed twice the 31 year running median absolute deviation by accounting for the dating uncertainties associated with each record these ice core records together reveal a large volcanogenic acid deposition event during 1453 1457 a d the results suggest only one major stratospheric injection from the kuwae eruption and confirm previous findings that the kuwae eruption took place in late 1452 or early 1453 which may serve as a reference to evaluate and improve the dating of ice core records the average total sulfate deposition from the kuwae eruption was 93 kg so4 km 2 in antarctica and 25 kg so4 km 2 in greenland the deposition in greenland was probably underestimated since it was the average value of only two northern greenland sites with very low accumulation rates after taking the spatial variation into consideration the average kuwae deposition in greenland was estimated to be 45 kg so4 km 2 by applying the same technique to the other major eruptions of the past 700 years our result suggests that the kuwae eruption was the largest stratospheric sulfate event of that period probably surpassing the total sulfate deposition of the tambora eruption of 1815 which produced 59 kg so4 km 2 in antarctica and 50 kg so4 km 2 in greenland