a multiproxy approach to reconstructing sea surface conditions using coral skeleton geochemistry 1 we use elemental ratio mg ca sr ca u ca and ba ca and oxygen isotope data from a porites lutea coral head collected from offshore amedee island new caledonia 22 29 s 166 28 e to assess the degree to which changes in these geochemical variables reflect variations in sea surface conditions we have assessed the robustness of each geochemical proxy by comparing 25 years 1992 1968 of monthly geochemical variations with a local record of sea surface temperature sst and with the appropriate 1 by 1 grid box from a global gridded sst data set we conclude from our comparison that the most consistent proxies of monthly sst variations at this site are 18o r2 0 84 p 0001 and sr ca r2 0 84 p 0001 the fidelity of the coral based sr ca sst proxy was assessed via calibration verification exercises at new caledonia and rarotonga the paleoclimate accuracy of the coral sr ca sst technique is judged to be robust and the precision of the technique is estimated to be 0 3 0 5 2 based on the calibration verification exercise in contrast monthly variations in mg ca and u ca ratios are only moderately correlated with monthly sst variations r2 0 55 p 0001 for mg ca and r2 0 47 p 0001 the strength of the correlation between sst and mg ca and u ca varies as a function of time suggesting that variations in these ratios are not a simple function of sst variations this variability in goodness of fit between u ca sst and mg ca sst may ultimately limit the use of these ratios as coral paleothermometers averaging or stacking individual proxy sst records sr ca mg ca and u ca to generate a composite proxy sst record does not necessarily improve the proxy record if the signal to noise ratio in each proxy is highly variable for example stacking of sr ca mg ca u ca records at new caledonia produces a proxy sst time series that has greater standard error than the individual sr ca sst time series cf ordinary least squares standard error of 1 16 c versus 0 86 c ba ca variations have little correlation with sst sr ca mg ca or u ca variations at new caledonia in conclusion variations in oxygen isotopic composition of seawater calculated by removing the sr ca based temperature component of the 18o signal agree reasonably well with observed variations in sea surface salinity especially at the interannual timescale

surface ocean variability at galapagos from 1936 1982 calibration of geochemical tracers in corals a variety of geochemical tracers has been developed in reef corals as a means of reconstructing the natural variability of the tropical surface ocean over wide ranging time frames the purpose of this paper is to calibrate the performance of five of these tracers in a modern coral colony over an extended period a 47 year growth interval 1936 1982 in a colony of pavona clavus taken from san cristobal island galapagos islands was sectioned into 187 quarterly intervals and analyzed for 18o 13o ba ca cd ca and mn ca the resulting time series are compared with eastern pacific sea surface temperatures one of few instrumental data bases available for calibration over this time period linear least squares regressions of four of the tracers 18o 13o ba ca cd ca against peruvian sst show highly significant correlations p 0 0001 over the annual biennial and enso 3 8 years frequency bands cross spectral comparisons show even stronger coherency with sst frequently accounting for 70 80 of the variance in these tracers these results as well as the phase relationships determined from the spectral analyses suggest that the coupling between sst and 18o and the nutrientlike tracers ba and cd is controlled principally by seasonal upwelling cycles and interannual interruptions of these cycles brought about by el nino and anti el nino phenomena an inverse relationship between sst and 13c has its primary origins in the co occurrence of the warm sst phase with high light levels during the first half of the calendar year the association with sunlight derives from the photosynthetic response of algal symbionts which results in fractionation of light and heavy carbon isotopes between soft tissues and caco3 skeleton the fifth tracer the transition metal mn exhibits poorer correlations against both sst and the other tracers slight shifts in phasing of the historical mn ca annual cycle suggest that the general water column distribution of this tracer which is the reverse of a nutrient may not be stable the erratic behavior of mn illustrates how complex hydrography near galapagos may influence tracers with diverse source signatures

strontium calcium ratios in modern porites corals from the great barrier reef as a proxy for sea surface temperature calibration of the thermometer and monitoring of enso high precision sr ca ratios are reported for porites corals from davies reef at 19 s on the midshelf of the great barrier reef australia skeletal growth parameters were also determined from coral slabs using x ray photographs and densitometry measurements a calibration of the sr ca thermometer has been obtained using in situ measured sea surface temperatures which gives sr ca 10 10 48 0 01 0 0615 0 0004 t wheret is in c this calibration applies to different species of porites and a large range of annual extension and calcification rates provided sampling follows a major growth axis biases of 1 2 c have been observed in the low density margins where growth is hampered by interfering fans of corallites the analytical and the long term reproducibility of sr ca derived temperatures are both better than 0 3 c 2 coral growth parameters such as the extension rate or density generally appear to respond to environmental changes such as rainfall but do not affect the sr ca partitioning between coralline aragonite and seawater no correlation has been found between calcification rate and sr ca variations consistent with sr ca being mainly controlled by temperature in the great barrier reef the interannual variability in sst is primarily related to the el nino southern oscillation phenomenon and is typically marked by a cold anomaly during the winter preceding the mature warm phase instrumental records show that the surface waters of the coral sea around 19 s have experienced a significant cooling associated with the el ninos of 1965 1972 and 1982 1983 which the porites corals record faithfully the coral derived temperatures for the period from 1965 to 1993 show an increase of 1 3 c which has occurred mainly since 1979 this warming is larger in magnitude but consistent with the trend for the southern hemisphere land and marine temperature records which shows an increase of around 0 4 c

pacific sea surface temperature field reconstruction from coral δ18o data using reduced space objective analysis 1 a systematic methodology for the reconstruction of climate fields from sparse observational networks of proxy data employing the technique of reduced space objective analysis is applied to the reconstruction of gridded pacific ocean basin sea surface temperature sst from coral stable isotope 18o data for the period 1607 1990 in this approach we seek to reconstruct only the leading modes of large scale variability which are both observed in the modern climate and resolved in the proxy data we find that the coral data verifiably resolve two spatial patterns of sst variability the first and dominant pattern is that of the el nino southern oscillation enso a second pattern reflects uniform changes over most of the pacific basin calibration and verification tests for 1856 1990 show that root mean square variance is small 0 5 c rms and reconstruction errors are large 0 6 c rms limiting interpretation to the tropical region periods of enhanced enso activity similar to those observed in the past two decades are evident in the reconstruction for the early nineteenth century the changing frequency of enso warm phase events appears to coincide with warming of the pacific mean state inferred from similar reconstruction efforts using tree ring indicators over the last two centuries

evidence for a volcanic cooling signal in a 335 year coral record from new caledonia although volcanic cooling events have been detected in tree ring records their occurrence in marine records has received much less attention herein we report results from a 335 year oxygen isotope record 1657 1992 from a new caledonia coral indicating that as many as 16 interannual scale cooling events occur within 1 year of a volcanic eruption as determined by ice core records there are also pentadal decadal scale cooling events beginning in 1675 1813 and 1903 that immediately postdate volcanic eruptions however the interannual correspondences are complicated by the fact that some of the cooling events also coincide with el ninos which cause cooling in this part of the western south pacific if our conclusions are substantiated by further work occurrence of distinct volcanic cooling signals may enable refinement of coral chronologies by use of the event stratigraphic approach with the most promising correlation horizons being associated with the following eruptions 1808 unknown 1813 1821 several eruptions 1835 coseguina 1883 krakatau and possibly 1963 agung

stable isotope geochemistry of corals from costa rica as proxy indicator of the el nino southern oscillation enso abstract we analyzed the 18 o and 13 c time series contained in coral skeletons collected from isla del cano costa rica that survived the 1982 1983 el nino warming event coral 18 o give a record of thermal histories with a precision of 0 5 c for this locality we have determined that the average w effect in the coral skeletons is equivalent to 33 of the skeletal 18 o range therefore if w effects are not compensated for the annual skeletal 18 o range displays a temperature range of 1 c lower than actual values the isotopic record of porites lobata skeletons shows simultaneous depletions in 18 o and 13 c at skeletal levels corresponding to 1983 coincident with the el nino southern oscillation enso event therefore the el nino event is not only recorded as negative 18 o anomalies in the skeleton suggesting the warming of ambient waters but also in the 13 c signal as negative anomalies indicating coral bleaching contrary to the predictions of the 13 c insolation model that the annual carbon isotope variation should be attenuated with depth in proportion to the decrease in light intensity variation with depth we found a clear trend where 13 c increases with depth coral bioenergetics which depends on both coral physiology and ecology may adequately explain the unexpected increase in 13 c range with depth without contradicting the seasonal character of 13 c variability with the solar irradiance cycle although some authors have determined the presence of hiatuses in the skeletal record due to severe stress and growth cessation in this study it has been found that skeletal growth was not seriously diminished during the el nino year of 1983 we attribute the good agreement of the 18 o record with the timing and magnitude of the el nino 1982 1983 warming event to the nature of the warming trend in the area as well as to some synergistic implications of coral tolerance to thermal stress

a chemical indicator of trade wind reversal in corals from the western tropical pacific historical levels of manganese have been measured in the annual rings of a reef coral from tarawa atoll 1 30 n 173 e in order to assess the temporal variability of this trace element in surface waters of the western tropical pacific seasonal variability associated with vertical mixing is not apparent as is the case in the eastern pacific however mn ca ratios are highly perturbed during three el nino southern oscillation enso events 1965 1972 1976 that occurred within the growth period 1960 1977 for approximately 6 months during each of these events mn ca ratios increase by 50 80 from a background of 27 nmol mn mol ca these features co occur with negative 18o pulses recorded in the same coral which result from anomalously abundant rainfall wet deposition of mn however does not appear to be an adequate source to account for the inferred surface ocean enrichments the most plausible explanation has to do with the transient appearance of westerly winds along the equator during enso periods particularly vigorous westerly wind bursts sometimes averaging 10 m sec or more over 16 hours during the aforementioned years may have generated wind waves of sufficient strength to create an aura of particulate and diagenetically remobilized mn from within the shallow westward facing lagoon of tarawa this interpretation is supported by relatively high mn concentrations measured in pore waters of tarawa lagoon sediments the results suggest a useful new chemical tracer of historical enso conditions in the western pacific basin

mg ca sr ca and u ca ratios of a porites coral from sanya bay hainan island south china sea and their relationships to sea surface temperature high resolution mg ca sr ca and u ca ratios are reported in the skeleton of porites sp collected from sanya bay on the south coast of the hainan island china using inductively coupled plasma mass spectrometry combined with isotope dilution technique icp ms id the coralline mg ca ratios covary with sea surface temperatures sst for the 10 year interval giving the relationship between mg ca and sst as t degrees c 14 13 0 31 8 846 0 068 x 10 3 mg ca with the mean square weighted deviation mswd of 9 7 using this equation we are able to reconstruct sst record with a precision better than 0 5 degrees c several sr ca and u ca ratios show poor linear relationships with the measured sst this study indicates that the growth rates of the coral do not significantly affect coralline mg ca sr ca and u ca ratios however the high meteoric precipitation in this area which may cause a heavy run off from the island may change seawater sr ca and u ca ratios and ruin the relationships between coralline sr ca or u ca ratios and sst this implies that in coastal areas like hainan coralline mg ca ratios are valid for reconstructing the sst records but sr ca and u ca ratios may be suspected c 2000 elsevier science b v all rights reserved

a central tropical pacific coral demonstrates pacific indian and atlantic decadal climate connections while instrumental and proxy based climate records describe significant decadal scale climate variabil ity throughout the tropical pacific indian and atlantic oceans the processes responsible for these variations and their interactionsare not readily apparent from the obs er vations a new 112 yr coral based sea surface temperature sst reconstruction from palmyra island in the central tropical pacific ctp exhibitss trong decadal variability with an amplitude of roughly 0 3 c a 12 13yr period sig nal in thiscoral record ishighly coherent with long equa torial atlantic and indian ocean climate records implying a unified phenomenon the atlantic pattern suggests that it may fall under direct influence of anomaloussst in the ctp as it does over interannual timescales while the in dian ocean pattern exhibits maximum response during the switch between warm cold states in the tropical pacific the results demonstrate that the ctp has played a significant role in determining the expression of global decadal climate variability over the twentieth century

monsoon tropical ocean interaction in a network of coral records spanning the 20th century abstract the 20th century evolution of basin wide gradients in surface ocean properties provides one essential test for recent models of the interaction between the asian monsoon and the tropical ocean because various feedback mechanisms should result in characteristic regional patterns of variability although the instrumental record of climate variability in the tropics is essentially limited to the last few decades the stable isotopic composition of living corals provides an effective means for extending the instrumental observations here we present two coral isotopic records from the indonesian maritime continent and we use these records with other previously published records to describe i the relationship between western pacific and central pacific climate variability over the past century with special emphasis on the biennial band and ii the strength of the west east indian ocean dipole we find that the amplitude of the biennial cycle in the pacific did not vary inversely with the strength of enso el nino southern oscillation as might be expected from some models of monsoonal feedback on the central pacific instead the biennial variability was modulated on decadal timescales throughout much of the pacific we also show that the zonal oxygen isotopic gradient in the indian ocean coral records was significantly correlated with central pacific sea surface temperature on a variety of timescales thus it is likely that this coral dipole was a product of strong enso like teleconnections over the indian ocean as opposed to being the result of unique indian ocean or monsoonal dynamics

a coral oxygen isotope record from the northern red sea documenting nao enso and north pacific teleconnections on middle east climate variability since the year 1750 a 245 year coral oxygen isotope record from the northern red sea ras umm sidd egypt 28 n in bimonthly resolution is presented the mean annual coral 18o signal apparently reflects varying proportions of both sea surface temperature and 18oseawater variability in conjunction with instrumental observations of climate the coral record suggests for interannual and longer timescales that colder periods are accompanied by more arid conditions in the northern red sea but increased rainfall in the southeastern mediterranean whereas warmer periods are accompanied by decreased rainfall in the latter and less arid conditions in the northern red sea a 70 year oscillation of probably north atlantic origin dominates the coral time series interannual to interdecadal variability is correlated with instrumental indices of the north atlantic oscillation nao the el nino southern oscillation enso and north pacific climate variability the results suggest that these modes contributed consistently to middle east climate variability since at least 1750 preferentially at a period of 5 7 years

interaction between the enso and the asian monsoon in a coral record of tropical climate the oxygen isotopic composition of a banded coral from the western equatorial indian ocean provides a 150 year long history of the relation between the el nino southern oscillation enso phenomenon and the asian monsoon interannual cycles in the coral time series were found to correlate with pacific coral and instrumental climate records suggesting a consistent linkage across ocean basins despite the changing frequency and amplitude of the enso however decadal variability that is characteristic of the monsoon system also dominates the coral record which implies important interactions between tropical and midlatitude climate variability one prominent manifestation of this interaction is the strong amplitude modulation of the quasi biennial cycle

a mid twentieth century reduction in tropical upwelling inferred from coralline trace element proxies abstract the cariaco basin is an important archive of past climate variability given its response to inter and extratropical climate forcing and the accumulation of annually laminated sediments within an anoxic water column this study presents high resolution surface coral trace element records montastrea annularis and siderastrea siderea from isla tortuga venezuela located within the upwelling center of this region a two fold reduction in cd ca ratios 3 5 1 7 nmol mol is observed from 1946 to 1952 with no concurrent shift in ba ca ratios this reduction agrees with the hydrographic distribution of dissolved cadmium and barium and their expected response to upwelling significant anthropogenic variability is also observed from pb ca analysis observing three lead maxima since 1920 kinetic control of trace element ratios is inferred from an interspecies comparison of cd ca and ba ca ratios consistent with the sr ca kinetic artifact but these artifacts are smaller than the environmental signal and do not explain the cd ca transition the trace element records agree with historical climate data and differ from sedimentary faunal abundance records suggesting a linear response to north atlantic extratropical forcing cannot account for the observed historical variability in this region

the changing relationship between enso variability and moisture balance in the continental united states the el nino southern oscillation enso system orchestrates a well documented suite of climate anomalies worldwide the details of enso s extratropical influence vary among events but this variability has not been described or diagnosed beyond the past few decades and previous descriptions have looked at inter event differences rather than decadal patterns we use a new tree ring based drought reconstruction for the continental u s and instrumental enso indices to document systematic decadal changes in the u s drought enso relationship since the late 19th century significant enso drought correlation occurs consistently in the southwest u s but the strength of penetration of moisture anomalies into the continent varies substantially the most striking change over the past 130 years is the initiation of a bipolar enso drought signature around 1920 producing opposite sign moisture anomalies in the southwest and mid atlantic states shifts in teleconnection patterns coincide with variations in the strength of enso and in a north pacific mode

a review of modern coral δ18o and δ14c proxy records abstract this paper is a review of published modern coral 18 o and 14 c isotopic records that are at least 30 and 20 years long respectively the data are presented to show basin scale trends in both of these proxy records on decadal to centennial timescales the goal was to qualitatively integrate the general inter annual to centennial timescale variability revealed in these data as well as the statistical and modeling output results that have been produced using these coral records while many review papers typically include a representative subset of the data available this review aims to include as much of the available data as possible in general coral 18 o records show a long term warming and or freshening throughout the tropical oceans and agree with the noaa extended reconstruction sea surface temperature 2 ersst on decadal timescales in the western pacific it is most likely a freshening of the seawater 18 o that dominates the signal el nino southern oscillation enso variability dominates most 18 o records either by varying local seawater temperature or salinity depending on the regional oceanography climatology outside of the pacific enso affects seawater temperature and salinity via atmospheric or oceanic teleconnections post bomb coral 14 c records collectively show that the uptake of 14 c has been greatest in gyre water fed sites followed in descending order by western boundary current areas equatorial upwelling regions and eastern tropical pacific upwelling sites these surface water 14 c values indicate the proportion of surface water and or the residence time of water at the surface at a given location and can be used to model water mass mixing rates such models have only begun to be run and show that the amount of eastern pacific water entering the central south pacific increases during el ninos and that the indonesian throughflow is supplied year round by the north pacific comparing ocean circulation models with coral 14 c modelled circulation enables researchers to explore the mechanisms that drive seawater 14 c variability and fine tune their models in addition our comparison between the rate of coral 14 c increase between 1960 and 1970 and total anthropogenic co 2 uptake rates show general agreement demonstrating the value of coral records in understanding past carbon fluxes overall coral 18 o and 14 c proxy records represent natural archives of seawater conditions and are critical for studying the natural variability in local and regional patterns within and teleconnection patterns between the tropics extra tropics temperate and polar regions on intra annual to centennial timescales

deconvolving the δ18o seawater component from subseasonal coral δ18o and sr ca at rarotonga in the southwestern subtropical pacific for the period 1726 to 1997 to reconstruct oceanographic variations in the subtropical south pacific 271 year long subseasonal time series of sr ca and delta 18 o were generated from a coral growing at rarotonga 21 5degreess 159 5degreesw in this case coral sr ca appears to be an excellent proxy for sea surface temperature sst and coral delta 18 o is a function of both sst and seawater delta 18 o composition delta 18 o sw here we focus on extracting the delta 18 o sw signal from these proxy records a method is presented assuming that coral sr ca is solely a function of sst and that coral delta 18 o is a function of both sst and delta 18 o sw this method separates the effects of delta 18 o sw from sst by breaking the instantaneous changes of coral delta 18 o into separate contributions by instantaneous sst and delta 18 o sw changes respectively the results show that on average delta 18 o sw at rarotonga explains similar to39 of the variance in delta 18 o and that variations in sst explains the remaining similar to61 of delta 18 o variance reconstructed delta 18 o sw shows systematic increases in summer months december february consistent with the regional pattern of variations in precipitation and evaporation the delta 18 o sw also shows a positive linear correlation with satellite derived estimated salinity for the period 1980 to 1997 r 0 72 this linear correlation between reconstructed delta 18 o sw and salinity makes it possible to use the reconstructed delta 18 o sw to estimate the past interannual and decadal salinity changes in this region comparisons of coral delta 18 o and delta 18 o sw at rarotonga with the pacific decadal oscillation index suggest that the decadal and interdecadal salinity and sst variability at rarotonga appears to be related to basin scale decadal variability in the pacific copyright c 2002 elsevier science ltd

radiocarbon as a thermocline proxy for the eastern equatorial pacific an ocean model is used to test the idea that sea surface delta 14 c behaves as a thermocline proxy in the eastern equatorial pacific the orca2 model which includes delta 14 c as a passive tracer has been forced with reanalysis fluxes over 1948 1999 and the output is compared with a previously reported galapagos delta 14 c record the model reproduces the abrupt increase in the seasonally minimum delta 14 c in 1976 77 found in the data this increase is associated with neither a shift of thermocline depth over the nino3 region nor a change in the relative proportion of northern southern source waters rather it is due to a decrease in the sub antarctic mode water samw component of the upwelling water thereby representing a decrease in entrainment of water from below the base of the directly ventilated thermocline

reliability of coral isotope records from the western pacific warm pool a comparison using age optimized records stable isotope analysis of two separate corals from nauru island in the warm pool of the western tropical pacific confirm that coral oxygen isotopes are a robust recorder of environmental variables coral delta 18 o faithfully records interannual variability even when strongly influenced by kinetic effects interannual to decadal variability of coral delta 13 c remains enigmatic only one of the two corals exhibits the expected light delta 13 c response in the interannual band coral delta 18 o from this region has a great similarity to global instrumental temperature records reflecting the impact of the pacific warm pool and variations of the indonesian low in concert with el nino southern oscillation on global climate since 1896 coral delta 18 o has exhibited a cumulative decrease of 0 7 parts per thousand which reflects a combination of warming and more frequent el nino events precipitation affecting the surface waters of this region

rapid analysis of high precision sr ca ratios in corals and other marine carbonates a method for rapid determination of high precision sr ca ratios in scleractinian corals is presented using an inductively coupled plasma atomic emission spectrophotometer samples are corrected for instrument drift using a reference solution similar to the approach used for analysis of stable isotopes using gas source mass spectrometry further correction for variation of the sr ca ratio with ca concentration is accomplished using internal standards the precision once all corrections have been made is better than 0 1 relative standard deviation 1 for samples of similar ca concentration and better than 0 2 for samples with variable ca concentrations this method increases the sample throughput by approximately a factor of 20 relative to thermal ionization mass spectrometry and significantly reduces instrument and per sample costs comparison of sr ca data for a coral from the galapagos islands with an instrumental temperature record shows excellent agreement and demonstrates the potential for application of this technique to samples of modern and fossil scleractinian corals and other marine carbonates including foraminifera

high resolution isotopic records from corals using ocean temperature and mass spawning chronometers abstract we present a 6 year long 1978 1984 18 o and 13 c record from a great barrier reef pandora reef porites lutea coral based on near weekly sample intervals a sampling technique was designed to minimise any smoothing or distortion of the isotopic record due to complex coral growth calyx architecture and calcification at depth within the tissue layer the arrival time of the mid winter minimum sea surface temperature is very consistent 2 weeks near pandora reef and provides an annual time marker offering more precision than the traditional density band chronometer the improved chronology and high resolution record demonstrate that signal distortion in porites due to calcification within the tissue layer and variable intra annual coral extension is generally negligible also confirmed is that the arrival time of monsoonal floods is precisely preserved 1 week within the skeleton of porites the sensitivity of weekly sampling allows the detection of a subtle warm to cool sea surface temperature anomaly which preceded by more than one year a similar temperature anomaly associated with the 1982 83 el nin o in the east pacific sharply higher 13 c values coincide with the time of the annual coral mass spawning event in the great barrier reef recognition of this mass spawning signal should simplify the interpretation of coral 13 c records and provides an additional precise time marker with which to adjust chronologies when intra annual coral extension is not constant

el nino southern oscillation enso and decadal scale climate variability at 10 n in the eastern pacific from 1893 to 1994 a coral based reconstruction from clipperton atoll we have developed a 101 year 1893 1994 subseasonal oxygen 18o and carbon 13c isotopic time series from clipperton atoll in the eastern pacific using the coral porites lobata in agreement with linsley et al 1999 we find that seasonal and interannual coral 18o variability at clipperton results from variability in both water temperature and salinity three new coral time series demonstrate the reproducibility of a secular coral 18o trend of 0 35 since 1910 but show varying 13c trends strong decadal scale variability in the 18o record appears related to the pacific decadal oscillation pdo through postulated changes in the strengths of the equatorial counter current and north equatorial current interannual variability in this coral 18o record is directly related to the el nino southern oscillation enso and isolation of this frequency band indicates reduced enso variability in the eastern equatorial pacific in the period 1925 to 1940 in agreement with instrumental and other pacific coral records

variability of the intertropical convergence zone recorded in coral isotopic records from the central indian ocean chagos archipelago we have analyzed the stable oxygen isotopic composition of two porites corals from the chagos archipelago which is situated in the geographical center of the indian ocean coral 18o at this site reliably records temporal variations in precipitation associated with the intertropical convergence zone itcz precipitation maxima occur in boreal winter when the itcz forms a narrow band across the indian ocean the chagos then lies within the center of the itcz and rainfall is strongly depleted in 18o a 120 yr coral isotopic record indicates an alternation of wet and dry intervals lasting 15 to 20 yr the most recent 2 decades are dominated by interannual variability which is tightly coupled to the el nino southern oscillation enso this is unprecedented in the 120 yr of coral record as the itcz is governed by atmospheric dynamics this provides evidence of a major change in the coupled enso monsoon system

evaluating southern red sea corals as a proxy record for the asian monsoon coral palaeoclimatic studies are under way at many sites throughout the wet tropics however arid environments have received less attention here we report a high resolution 63 yr record of coral 18o and 13c extracted from a porites colony from the dahlak archipelago off the eritrean coast in the southern red sea the annual cycles of the coral 18o and 13c are inversely related while their inter annual variations show a strong positive correlation with similar inter decadal trends inter annual variations in coral 18o show a relatively weak correlation with the southern red sea sst but are strongly correlated with the indian ocean sst especially on the decadal time scale the range of the inter annual variations in the coral 18o is high compared to changes in local sst due to the amplifying effect of simultaneous changes in water isotopic composition due to this amplification of the climate signal the coral provides a better indication of regional oceangraphic behaviour than the local sst record the norrtheast monsoon signal in the coral 18o dominates the mean annual signal and shows the best correlation with the instrumental data sets it appears that variations in the coral 18o are controlled mainly by variations in the intensity of surface water influx from the indian ocean to the red sea during the winter northeast monsoon of particular significance is that the decadal time scale variations in the coral skeletal 18o are closely correlated with both the indian ocean sst and with variations in the pacific based southern oscillation index that is isotopically light coral skeleton indicating strong ne monsoon red sea inflow correlates with periods of high indian ocean sst and with predominantly negative el nin o phases of the southern oscillation the simultaneous nature of inter decadal changes in asian monsoon and enso behaviour suggest pan indo pacific tropical climate reorganisation and evolution

abrupt changes in early holocene tropical sea surface temperature derived from coral records for many high latitude regions of the globe it is now clear that the transition to modern climate following the last glacial maximum was punctuated by a number of rapid and substantial climate oscillations1 2 in contrast relatively little is known about how the tropics responded to the deglaciation because few high resolution records are available from lower latitudes corals have recently been shown to provide an important source of tropical climate records because they can be easily and accurately dated using either 14c or 230th and because past sea surface temperatures can be recovered from the sr ca ratios in coral skeletons here we use this technique to derive several early holocene sea surface temperature records from a coral drill core recovered from espiritu santo vanuatu in the tropical southwest pacific ocean these records indicate that sea surface temperatures in this region were depressed by as much as 6 5 c below modern values at 10 350 calendar years bp but rose very abruptly during the following 1 500 years this temperature increase lags the post younger dryas increase observed in a coral record from the tropical atlantic ocean3by about 3 000 years an unexpected phase shift that may ultimately shed light on the mechanisms of deglacial climate change

evaluating the use of the massive coral diploastrea heliopora for paleoclimate reconstruction 1 to date coral based paleoclimate research in the pacific has primarily utilized core samples from the genus porites and has been most successful reconstructing past variability on interannual timescales particularly the el nino southern oscillation enso the indo pacific coral genus diploastrea however owing to its slower extension rate denser structure and longer lifespan can potentially preserve geochemical proxy records 2 3 times longer than porites cores of the same length before its potential can be realized diploastrea must first be calibrated and its climate signal assessed we present oxygen isotope 18o and sr ca results from two diploastrea cores collected in fiji 16 49 s 179 14 e that allow for simultaneous evaluation of this coral s paleoclimatic utility and the reproducibility of each tracer at this site comparison to a porites record from the same location allows for further evaluation of diploastrea as a paleoclimatic archive we demonstrate that diploastrea s septal and columellar material yield similar 18o sst relationships and that despite some sacrifice of the seasonal 18o amplitude bulk sampling of either region is satisfactory for resolving interannual and lower frequency modes of climatic variability therefore paleoclimate reconstructions employing either a septal or columellar sampling regime of this genus may be useful at filling in spatial and temporal sampling gaps which currently hinder the reconstruction of long term changes in major climate fields in the western pacific

eastern pacific sea surface temperature since 1600 a d the δ18o record of climate variability in galapagos corals we measured stable oxygen isotope ratios and skeletal growth rates in the massive corals pavona clavus and p gigantea from the west coast of isabela island galapagos to assess interannual to decadal climate variability in the eastern pacific comparisons of instrumental data sets show that sea surface temperatures sst in the galapagos region are representative of a broad portion of the eastern equatorial pacific the site is especially well suited for long term studies of the el nino southern oscillation enso phenomenon as it lies within the eastern pacific center of action for thermal anomalies associated with enso the p gigantea isotope record is nearly monthly in resolution spans the period 1961 1982 and shows strong correlation with a galapagos instrumental sst record r 0 90 for annual averages cross spectral analysis shows that sst can explain greater than 80 of the variance in 18o at both the annual cycle and within the high frequency portion of the enso band 3 5 years the p clavus record is annual in resolution extends from 1587 to 1953 a d and was obtained from a 10 m diameter colony preserved within the urvina bay uplift because seawater 18o variations in the region are very small we interpret the urvina bay coral 18o record in terms of annual average sst the isotopic record appears to be a very good but not perfect indicator of enso events and shows good correspondence with the historical enso reconstruction of quinn et al 1987 a number of low 18o excursions that we observe during the 17th and 18th centuries very likely represent enso events that are missing from the historical tabulations most interannual 18o variations between 1607 and 1953 a d represent annual average temperature excursions of 1 to 2 5 c during the little ice age the annual 18o series correlates well with many north american tree ring records and shows low temperatures during the early 1600s and early 1800s and relatively warmer conditions during the 1700s unlike most northern hemisphere tree ring and instrumental records we see no evidence at this site for warming between 1880 and 1940 but rather observe a slight cooling 28 of the total variance the main enso mode is centered at 4 6 years and accounts for 12 of the total variance additional significant oscillations occur at periods of 3 3 6 8 11 17 22 and 34 years both annual growth rate and 18o show variance at periods equivalent to the solar and solar magnetic periods e g 11 and 22 years respectively in addition the amplitude of the 11 year 18o cycle generally varies with the amplitude of the solar cycle supporting previous suggestions that the solar cycle may modulate interannual to decadal climate variability in the tropics the dominant oscillatory modes both within the enso and interdecadal frequency bands shift to shorter periods from the early to middle 1700s and again from the middle to late 1800s this may reflect major reorganizations within the tropical ocean atmosphere system and suggests that tropical pacific climate variability is linked across timescales ranging from years to decades

coral δ18o records as an indicator of winter monsoon intensity in the south china sea we have used correlative analysis between mean december january february winter wind velocities measured at the xisha meteorological observatory 16degrees50 n 112degrees20 e in the middle of the south china sea and mean 518 0 data for the corresponding month from porites lutea coral collected in longwan waters 19degrees20 n 110degrees39 e to obtain a linear equation relating the two datasets this winter wind velocity for the south china sea wmiiscs can then be correlated to the coral delta 18 o by the equation wmiiscs 1 213 1 351 delta 18 o parts per thousand pdb r 0 60 n 40 p 0 01 from this the calculated wmiiscs delta18o series from 1944 to 1997 tends to decrease during the 1940s to the 1960s it increases slightly during the 1970s and then decreases again in the 1980s and 1990s the calculated decadal mean wmiiscs delta18o series had a obvious decrease from 5 92 to 4 63 m s during the period of 1944 1997 the calculated yearly mean wmiiscs delta18o value is 5 58 m s from 1944 to 1976 and this decreases to 4 85 m s from 1977 to 1998 that is the opposite trend to the observed yearly mean sst variation the yearly mean sst anomaly is 0 27degrees from 1943 to 1976 and this increases to 0 16degrees from 1977 to 1998 spectral analysis used on a 54 year long calculated wmiiscs delta18o series produces spectral peaks at 2 4 7 yr which can be closely correlated with the quasibiennial oscillation band qbo band 2 2 4 yr and the el nino southern oscillation band enso band 3 8 yr hence most of the variability of the winter monsoon intensity in the middle of the south china sea is mainly constrained by changes in the thermal difference between the land and the adjoining sea area perhaps due to global warming c 2003 elsevier science usa all rights reserved

radiocarbon variability in the western equatorial pacific inferred from a high resolution coral record from nauru island we have generated a high resolution coral delta sup 14 c record spanning the last 50 years to document the seasonal and interannual redistribution of surface waters in the western tropical pacific prebomb 1947 endash 1956 delta sup 14 c values average minus 63 per thousand and have a total range of 30 per thousand values begin to increase in 1957 reaching a maximum of 137 per thousand in mid 1983 large interannual variability of up to 80 per thousand closely follows the el ni tilde n o southern oscillation enso during each enso warm phase delta sup 14 c values begin to increase reflecting the reduction of low sup 14 c water upwelling in the east and the invasion of subtropical water into the western equatorial tropical pacific maximum delta sup 14 c values are in phase or lag the corresponding sea surface temperature maxima in the eastern tropical pacific whereas the rapid return to more negative delta sup 14 c is in phase with eastern pacific enso indices the highest amplitude excursions occur during the 1965 1966 and 1972 1973 events when the sup 14 c contrast is highest between the eastern pacific and subtropics the 1982 1983 el ni tilde n o although a larger enso event has a lower delta sup 14 c amplitude reflecting the penetration of bomb radiocarbon into the equatorial undercurrent and the reduced contrast in delta sup 14 c betweenmore thermocline and subtropical surface waters at that time this coral record demonstrates the potential for using similar radiocarbon time series for documenting variability in pacific shallow circulation over interannual and decadal timescales copyright 1998 american geophysical union less

new views of tropical paleoclimates from corals abstract corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi decadal climate sensitivity is incomplete in the eastern equatorial pacific coral isotopic records track variations in enso related changes in sea surface temperature further west corals record variability in sea surface temperature and rainfall that accompanies zonal displacement of the indonesian low during enso events these multi century records reveal previously unrecognised enso variability on time scales of decades to centuries outside the enso sensitive equatorial pacific long term trends towards recent warmer wetter conditions suggest the tropics respond to global forcings new coral paleothermometers indicate that surface ocean temperatures in the tropical southwestern pacific were depressed by 4 6 c during the younger dryas climatic event and rose episodically during the next 4000 yr high temporal resolution measurements of sr ca and 18 o in corals provide information about the surface ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation radiocarbon measurements in corals coupled with ocean circulation models may be used to reconstruct near surface ocean circulation past mixing rates and the distribution of fossil fuel co2 in the upper ocean most recently seasonal to interannual variations in the radiocarbon of corals from the equatorial pacific have been linked to the redistribution of surface waters associated with the enso

trace metals in contemporary and seventeenth century galapagos coral records of seasonal and annual variations we report trace element calcium ratios for modern cuca mnca cdca and pbca and seventeenth century cuca mnca and pbca specimens of pavona clavus collected in the galapagos islands these data include the first reliable measurements of cuca ratios in coralline aragonite we estimate that the ratio of cuca in the lattice to that in seawater i e the effective distribution coefficient is 0 3 lower than the value of 1 observed for several other divalent elements we estimate the effective distribution coefficient for mn is 1 distribution coefficients in coral aragonite for 8 divalent metals are near unity despite different ionic radii and chemical speciation in seawater investigation of where these substituents are incorporated in the aragonite lattice is clearly warranted in a modern hood island coral quarter annually sampled from 1964 73 cuca ratios decrease twofold from the late 1960s to early 1970s mnca and cdca ratios vary seasonally with upwelling and the generic el nino the el nino southern oscillation enso events of 1965 1969 and 1972 are marked by suppression of cdca ratios by about 2 5 nmol mol while the mnca ratio is highest during the strong 1972 enso pbca ratios were relatively constant throughout this period from the cuca record of a seventeenth century urvina bay coral annually sampled from 1600 1725 and the estimated cu distribution coefficient surface seawater cu concentrations at galapagos during the seventeenth century were similar to present day at 0 7 1 4 nmol kg estimated pb concentrations were lower at 5 20 pmol kg and mn concentrations were slightly higher at 1 6 2 8 nmol kg

a 173 year stable isotope record from a tropical south pacific coral 0 we have generated a 173 year long time series a d 1806 to 1979 of changes in the 18 o and 13 c composition of a coral head platygyra lamellina to investigate environmental change in the climatologically sensitive region of the tropical south pacific little is known about decadal and centennial scale climate change at sea level in this region our coral is from near the south coast of espiritu santo island 15 s 167 e republic of vanuatu the stable isotope record from this coral is consistent with meteorological and oceanographic records during the period of overlap in the records 1964 1978 18 o values positively correlate with sst r 0 77 and 13 c values are highly coherent with rainfall r 0 82 at the annual cycle these relations suggest that the 18 o signal in this coral is a function of variations in sst and rainfall induced changes in sss whereas the 13 c signal may be related to rainfall and cloud cover modulation of photosynthesis in the coral 18 o and 13 c values are positively correlated over the entire length of the record r 0 65 a relation that is even stronger between 1806 and 1866 r 0 81 i e prior to the time of possible anthropogenic influence on the 13 c record because of the positive correlation between temperature and rainfall in this region we interpret the long term record of 18 o in terms of joint variations of these two variables the most significant cool dry excursion in the santo record occurs during the nineteenth century 1832 1866 and ends abruptly in 1866 with a change to modern values superimposed on this pattern is a slight 0 2 cooling drying toward the end of the twentieth century cross spectral analysis of the 18 o and 13 c records indicates a strong concentration of variance at the quasi biennial 2 years and el nino southern oscillation enso 4 5 years frequency bands in addition to a 15 year peak found also in global temperature records cross spectral analysis of coral isotope records from santo and the philippine sea indicate a concentration of variance at enso 4 5 years frequency bands however comparison of the santo coral isotope record with high latitude northern hemisphere temperature records indicates that the major cool dry excursion in the santo record 1832 1866 is not seen in the northern hemisphere record if verified in other tropical south pacific coral records the results have implications concerning the global scale of cooling for little ice age events

salinity records for the 1997 98 el nino from western pacific corals 1 seasonal sea surface salinity sss records can be of great value in reconstructing el nino southern oscillation enso variability in the equatorial western and central pacific a region where enso related evaporation and precipitation e p changes are dramatic the 18o values of coral skeleton 18ocoral reflect seawater 18o 18oseawater changes which in tropical oceans are also generally influenced by e p changes therefore 18ocoral is a good indicator of rainfall and enso variability we present biweekly data from palau in the northern part of the western pacific warm pool for the period 1998 2000 which indicate a strong quantitative relationship between 18ocoral sea surface temperature 18oseawater and sss the coral skeletal 18o values documented the sss changes after the 1997 98 el nino therefore 18ocoral can be used to estimate paleosalinity changes however the slope of the 18oseawater sss relationship cannot be assumed to be constant throughout the tropics making site specific calibrations is essential

the stable oxygen and carbon isotopic record from a coral growing in florida bay a 160 year record of climatic and anthropogenic influence abstract a 160 year record of skeletal 13 c and 18 o was examined in a specimen of the coral solenastrea bournoni growing in florida bay variations in the 18 o of the skeleton can be correlated to changes in salinity while changes in the 13 c reflect cycling of organic material within the bay based on the correlation between salinity and skeletal 18 o we have concluded that there has been no long term increase in salinity in this area of florida bay over the past 160 years using salinity correlations between the various basins obtained from instrumental data we have been able to extend our interpretations to other parts of florida bay reaching similar conclusions in contrast to current ideas which have focused on changes in florida bay water quality over the past 20 yr history of the bay as causative in its decline we have determined that changes in water quality in this basin were already set in motion between 1905 and 1912 by the construction of the florida east coast railway from miami to key west the construction of the railway resulted in the restriction of the exchange of water between the florida reef tract and the gulf of mexico causing florida bay to become more eutrophic evidence of this process is observed in the sudden shift to relatively lower 13 c values coincident with railway construction natural events also appear to have influenced the water in the bay between 1912 and 1948 frequent hurricanes had the effect of increasing exchange of water between the bay and reef tract and removing large quantities of organic rich sediments however since 1948 the number of hurricanes affecting the area has decreased and the products of the oxidation of organic material have been increasingly retained within the basin promoting the initiation of eutrophic conditions

influence of fissuring and karstification of the carbonate aquifer unsaturated zone on its vulnerability to contamination cracow upper jurassic region poland the carbonate fissure karstic aquifer of upper jurassic age is the main aquifer in the cracow upper jurassic region cujr the aquifer is recharged directly or indirectly by quaternary or quaternary cretaceous overburden of varying permeability which predominates diffused recharge concentrated recharge occurs locally and has a diverse nature field studies carried out in 20 quarries show moderate permeability of the unsaturated zone of carbonate massif karst funnels are filled with rubble and clay material and dominate filled fissures with an opening b 10 mm the average surface fissure porosity of massive with chalky limestones and bedded limestones reach 0 12 and 0 45 respectively while fissure permeability coefficient is respectively ks 6 60 10 5 and 1 27 10 3 m s the average karstification in quarries was determined as nk 2 5 tracer studies carried out in an unconfined carbonate zakrzowek horst in cracow krakow document vertical migration of infiltrating water through the systems with different hydraulic resistance with a flow rate from 8 1 10 6 to 4 9 10 5 m s and the lateral migration velocity between communicated caves from 6 94 10 6 to 1 06 10 4 m s the significant presence of poorly permeable overburden and moderate fissuring and karstification of rock in the unsaturated zone of cujr are reflected in the assessment of the upper jurassic aquifer vulnerability to contamination performed by a modified drastic method in the area of unconfined karst occupying 55 of the area vulnerability to contamination is high while as much as 45 of the area is characterized by medium and low vulnerability

the thermal oceanographic signal of el nino reconstructed from a kiritimati island coral central equatorial pacific sea surface temperature sst anomaly is a critical predictor of basin wide oceanographic and atmospheric effects of the el nino southern oscillation enso phenomenon we employ two geochemical thermometers measured on coralline aragonite to reconstruct an independent proxy based measure of central equatorial pacific sea surface temperature anomaly in addition we assess the observational error associated with extraction of large scale sst anomalies from 18o and sr ca measurements on the basis of paired data for the 1981 1987 period rms error for the estimation of sst from kiritimati coral 18o is about 0 4 c assuming no seawater 18o influence for sr ca the observational error is about 0 5 c singular spectrum analysis of the 18o time series suggests that 1 3 of the variance is explained by sst anomaly and that this variance may be separated from other signals in the frequency domain the interannual component of the 18o record shares 70 variance with the interannual component of local sst anomaly estimates 0 84 and correlates as highly with nino3 region 150 w 90 w 5 n 5 s sst anomaly estimates comparison of annual averages of the 18o data with analyzed sst for 55 years suggests that the error in deriving annually averaged sst anomalies at kiritimati is about 0 4 c a global sst correlation analysis suggests significant correlation with the rest of the pacific basin and the tropical indian and atlantic sectors the ocean wide level of correlation achieved using the coral data is indistinguishable from that achieved using the nino3 sst anomaly index and suggests that a few well located coral reconstructions with low observational error may be sufficient to reconstruct the global sst anomaly field associated with enso activity

shift in enso teleconnections recorded by a northern red sea coral abstract el nino southern oscillation enso teleconnections over europe and the middle east are evaluated using an oxygen isotope coral time series from the northern red sea and various instrumental datasets a shift in the correlation between the nino 3 index and the red sea coral record in the 1970s is detected and it is shown that this shift can be attributed to nonstationary circulation regimes and related enso teleconnections it is found that positive anomalies of oxygen isotope in the red sea coral record from the middle 1930s to the late 1960s are associated with a strong pacific north atlantic teleconnection accompanied by a weak aleutian low a more zonal flow at midlatitudes and la nina conditions in tropical pacific in contrast positive anomalies of oxygen isotopes in the red sea coral after the 1970s are related to el nino conditions and weaker pan pacific atlantic circulation regimes using the window correlation of the northern red sea coral record with two coral records from the tropi

pulses of rapid ventilation in the north atlantic surface ocean during the past century the suess effect is a gradual decrease of the 14c 12c ratio in tree rings from 1870 to 1950 that is attributed mostly to the burning of 14c free fossil fuels for energy in contrast pre nuclear bomb high precision measurements of 14c 12c ratios in banded corals from the north atlantic ocean do not exhibit the expected suess effect instead large biennial to decadal shifts in the 14c 12c ratios appear throughout the coral records this pattern indicates that rapid pulses of increased mixing between surface and subsurface waters occurred in the north atlantic ocean during the past century

seasonal cycles of manganese and cadmium in coral from the galapagos islands manganese to calcium ratios in corals from the eastern and western galapagos demonstrate regional differences in seasonal trace metal cycling the variability of trace metal to calcium ratios within the galapagos islands points to their unique geographic setting as a major factor this region is influenced by several major oceanic currents e g the south equatorial current the equatorial undercurrent and the panama or el nino current and by extremely intense upwelling manganese to calcium ratios in a banded coral pavona clavus from isabela island the westernmost island in the galapagos have distinct seasonal cycles for the non el nino southern oscillation enso years 1946 1950 with lower ratios following intensified seasonal upwelling cadmium calcium ratios show less distinct seasonal cycles the near moderate enso event in 1951 is marked by the disruption of seasonal cycles in mnca and cdca ratios in contrast corals from islands further east in the galapagos hood island 1964 1973 linn et al 1990 san cristobal 1965 1979 shen and sanford 1990 have stronger seasonal cdca signals with higher ratios following seasonal upwelling and less distinct seasonal cycles in mnca ratios one half year out of phase with cdca variations average mnca ratios are lower for these corals from locations further east indicating that urvina bay appears to have an additional localized source of mn shen and sanford 1990 in general these regional variations in seasonal trace metal cycling are consistent with coral stable isotope signals and with their geographic locations these variations are important to consider in using coral records to reconstruct and interpret oceanographic events occurring prior to historical records

vertical water mass mixing and plankton blooms recorded in skeletal stable carbon isotopes of a red sea coral the environmental interpretation of the 13c 12c variations in the skeletons of massive corals is still a matter of debate a 19 year seasonal skeletal 13c 12c record of a shallow water porites coral from the northern red sea gulf of aqaba documents interannual events of extraordinarily large plankton blooms indicated by anomalous 3c depletions in the coral skeleton these blooms are caused by deep vertical water mass mixing convectively driven in colder winters which results in increased supplies of nutrients to the surface waters the deep vertical mixings can sometimes be driven by the cooling occurring throughout the middle east after large tropical volcanic eruptions we therefore have evidence in our coral skeletal 13c 12c record for an indirect volcanic signal of the eruptions of e1 chich6n 1982 and mount pinatubo 1991 deep mixing induced 13c 12c variations of the dissolved inorganic carbon in the surface waters can be neglected at this location we therefore suggest that the 3c skeletal depletions can be best explained by changes in the coral s autotrophy heterotrophy diet through increased heterotrophic feeding on zooplankton during the blooms increased feeding on 3c depleted zooplankton or increased heterotrophy at the expense of autotrophy can both 3 result in a c depleted coral skeleton however this suggestion requires more testing if our conclusions are substantiated seasonal skeletal 3c r2c records of corals which change from autotrophy under normal conditions to increased heterotrophy during bloom events may be used as indicators of ocean paleoproductivity at interannual resolution available from no other source

decade time scale variability of ventilation in the north atlantic high precision measurements of bomb radiocarbon in banded corals the first high precision radiocarbon measurements for the upper ocean are presented for banded corals from two sites in the north atlantic ocean the striking dissimilarities between the post 1950 records at bermuda in the sargasso sea and the florida straits in the gulf stream illustrate the different mixing processes in the upper ocean at each site convective overturn associated with 18 degree water formation during late winter in the northern sargasso sea facilitates storage of considerable quantities of bomb radiocarbon at depth which accounts for the damping of the 14c signal at bermuda during the 1960s a multibox isopycnal mixing model is used to estimate the ventilation rate of the upper 700 m of the water column in the sargasso sea from 1950 to 1983 an inverse model is used that is the water mass renewal rate was calculated for the post bomb period in order to satisfy the bomb radiocarbon time history in the corals sea water radiocarbon measurements made during the geosecs 1972 1973 and transient tracers in the ocean 1980 1981 surveys are used to constrain the subsurface radiocarbon values calculated by the model results show that the rate of water mass renewal in the sargasso sea was high during 1963 1964 decreased during the late 1960s and remained low during most of the 1970s the 14c derived record of water mass renewal precedes by about 4 years that derived from isopycnal salinity in the sargasso sea jenkins 1982 illustrating that the coral 14c record is controlled to a large extent by changes in ocean circulation rather than by atmospheric exchange of co2

porites corals as recorders of mining and environmental impacts misima island papua new guinea abstract in 1989 open cut gold mining commenced on misima island in papua new guinea png open cut mining by its nature causes a significant increase in sedimentation via the exposure of soils to the erosive forces of rain and runoff this increased sedimentation affected the nearby fringing coral reef to varying degrees ranging from coral mortality smothering to relatively minor short term impacts the sediment associated with the mining operation consists of weathered quartz feldspar greenstone and schist these rocks have distinct chemical characteristics rare earth element patterns and high abundances of manganese zinc and lead and are entering the near shore environment in considerably higher than normal concentrations using laser ablation inductively coupled plasma mass spectrometry la icp ms we analyzed eight colonies two from high sedimentation two transitional two minor and two unaffected control sites for y la ce mn zn and pb all sites show low steady background levels prior to the commencement of mining in 1988 subsequently all sites apart from the control show dramatic increases of y la and ce associated with the increased sedimentation as well as rapid decreases following the cessation of mining the elements zn and pb exhibit a different behavior increasing in concentration after 1989 when ore processing began and one year after initial mining operations elevated levels of zn and pb in corals has continued well after the cessation of mining indicating ongoing transport into the reef of these metals via sulfate rich waters rare earth element ree abundance patterns measured in two corals show significant differences compared to coral sea seawater the corals display enrichments in the light and middle rees while the heavy rees are depleted relative to the seawater pattern this suggests that the nearshore seawater ree pattern is dominated by island sedimentation trace element abundances of misima island corals clearly record the dramatic changes in the environmental conditions at this site and provide a basis for identifying anthropogenic influences on corals reefs

decadal sea surface temperature variability in the subtropical south pacific from 1726 to 1997 a d we present a 271 year record of sr ca variability in a coral from rarotonga in the south pacific gyre calibration with monthly sea surface temperature sst from satellite and ship measurements made in a grid measuring 1 degrees by 1 degrees over the period from 1981 to 1997 indicates that this sr ca record is an excellent proxy for sst comparison with sst from ship measurements made since 1950 in a grid measuring 5 degrees by 5 degrees also shows that the sr ca data accurately record decadal changes in sst the entire sr ca record back to 1726 shows a distinct pattern of decadal variability with repeated decadal and interdecadal sst regime shifts greater than 0 75 degrees c comparison with decadal climate variability in the north pacific as represented by the pacific decadal oscillation index 1900 1997 indicates that several of the largest decadal scale sst variations at rarotonga are coherent with sst regime shifts in the north pacific this hemispheric symmetry suggests that tropical forcing may be an important factor in at least some of the decadal variability observed in the pacific ocean

evaluation of sampling resolution in coral stable isotope records a case study using records from new caledonia and tarawa we have generated a 40 year long monthly stable isotope record from a porites lutea coral collected offshore of amedee new caledonia 22 s 167 e to investigate the relation between sampling resolution in coral isotope studies and retrieval of sea surface environmental information we interpret the high correlation between our oxygen isotope record and a twenty year long sea surface temperature record at the monthly timescale r 0 88 to indicate that our coral isotope record is an accurate monitor of environmental conditions offshore of amedee the character of the signal and the percent variance explained in the record at the annual band at the quasi biennial oscillation band qbo 2 0 2 4 years and at the el nino southern oscillation band enso 3 8 years changes little in response to a reduction in sampling density from monthly to bimonthly to quarterly similar results have been obtained in a reanalysis of a coral isotope record from tarawa kiribati our results indicate that a significant amount of the information obtained from high density sampling can also be retrieved from lower density sampling in particular bimonthly sampling yields virtually no drop off in variance explained and quarterly sampling is satisfactory for resolving interannual and decadal scale trends in time series the proposed sampling approach may enable a more rapid filling in of numerous spatial holes in coral sampling sites needed for reconstruction of long term decadal scale variations in climate

a multicentury stable isotope record from a new caledonia coral interannual and decadal sea surface temperature variability in the southwest pacific since 1657 a d a 335 year stable isotope record from a new caledonia coral 22 s 166 e helps fill a large gap in historical climate reconstructions although the long term coral 18o based sea surface temperature sst trend is one of warming there are notable decadal fluctuations especially in the early 18th and early 19th centuries mean annual ssts between 1658 and 1900 are estimated to be 0 3 c lower than the 20th century average with interdecadal excursions of 0 5 0 8 c time series analyses of the coral isotope record reveals significant concentrations of variance in the el nino band an inderdecadal spectral peak is present but its robustness requires additional statistical evaluation a secular but irregular decrease in coral 13c values begins in the mid 1800s and may reflect the anthropogenic perturbation of the carbon reservoir these and other results indicate that the new caledonia coral isotope record is a valuable source of information on southwest pacific climate history

atmospheric and oceanic evidences of el nino southern oscillation events in the south central pacific ocean from coral stable isotopic records over the last 137 years we measured 18o and 13c in porites lutea collected in the moorea lagoon where the instrumental records show that an el nino southern oscillation enso event implies both a cloud cover decrease and a weak sea surface temperature sst increase two proxies allow an enso record to be reconstructed at moorea the annual 13c anomaly associated with the south pacific convergence zone motion and an annual 18o anomaly showing increased sst the frequency bands exhibited by the singular spectral analysis ssa and the multitaper method of the annual 18o and 13c records are centered on 2 5 and 5 2 years and 2 4 and 3 2 years respectively which are the main enso modes we used ssa to reconstruct enso events at moorea over the past 137 years results indicate that climate variability at this site is strongly affected by enso events

abrupt shift in subsurface temperatures in the tropical pacific associated with changes in el nino radiocarbon 14c content of surface waters inferred from a coral record from the galapagos islands increased abruptly during the upwelling season july through september after the el nino event of 1976 sea surface temperatures ssts associated with the upwelling season also shifted after 1976 the synchroneity of the shift in both 14c and sst implies that the vertical thermal structure of the eastern tropical pacific changed in 1976 this change may be responsible for the increase in frequency and intensity of el nino events since 1976

radiocarbon in annual coral rings from the eastern tropical pacific ocean sixty radiocarbon measurements were performed on aragonite from annually banded corals collected from three sites in the galapagos islands preanthropogenic 14c values of coral that grew around a d 1930 averaged 70 this is substantially lower than average values previously reported 51 for corals from florida and belize in the western north atlantic ocean a decrease of 6 was noticed in coral that grew from 1930 to 1954 this decrease could be interpreted as a suess effect in surface ocean water the 100 increase in 14c for coral that grew from 1954 to 1973 is the result of bomb produced 14c that was introduced to the surface ocean waters the 14c levels in corals that grew during el nino years were considerably higher than those for normal years these higher values are attributed to the absence of up welling at the equator during el nino events

variability of surface ocean radiocarbon and stable isotopes in the southwestern pacific we present high precision radiocarbon 14c results and stable isotope 18o and 13c records for a coral from heron island 23 s 152 e and new stable isotope 18o and 13c records for annual coral bands from abraham reef 22 s 153 e in the southern great barrier reef studied earlier druffel and griffin 1993 these tracers provide unique information on the regional water mass history and together these data allow us to constrain the variability of circulation in the upper pacific over the past four centuries first we observe decreases in 18o of coral from abraham reef and heron island indicating an increase in sea surface temperature and or a decrease in surface salinity since 1850 second the small suess effect value 14c decrease from 1880 to 1955 due mostly to fossil fuel co2 observed previously at abraham reef druffel and griffin 1993 is confirmed in the measurements reported here from the heron island coral this value is low compared to those observed in other areas of the ocean druffel 1997 druffel and linick 1978 nozaki et al 1978 between 1880 and 1955 third we report alterations in the correlation between el nino events and the occurrence of low 14c which is indicative of long term change s in circulation in the sw pacific the 14c shifts reported here are not large but even small temporal changes in prebomb 14c suggest that important changes in the large scale state of the ocean have occurred such as a temporal change in circulation

a strategy to improve the contribution of coral data to high resolution paleoclimatology abstract various geochemical tracers measured in massive coral skeletons have the potential to compliment other sources of high resolution proxy climate information e g tree rings ice cores by providing paleoclimatic data from shallow water tropical ocean regions twenty previously published coral records 19 18o and one sr ca series between 54 and 346 years in length were examined for their local and larger scale relationships el nino southern oscillation with climate series were examined in a consistent manner over the same time periods and relationships were tested for stability through time the results demonstrate a spectrum of climatic interpretation ranging from 1 no significant relationship of the coral record with either local or larger scale climate variables 2 significant relationship of the coral record with climate but the relationship is not stable through time and 3 the coral record shows a significant and temporally stable relationship with climate which explains a significant and useful proportion of climate variance it is concluded that reliance to date on analyzing only one long coral core from a site has prevented identification of coral records or parts of coral records where non climatic factors are dominating the geochemical signal various factors may cause these non climatic signals to dominate more process studies into how corals of particular species with various growth rates and from various environmental settings incorporate geochemical tracers into their skeleton are required to understand exactly what is being measured in addition it is recommended that some level of replication ideally three separate corals of geochemical tracers will ensure accurate dating of the record identification of periods when non climatic factors dominate and thus enhance the reliability of the paleoclimatic record such an approach will allow the rich archive of environmental information contained in massive coral skeletons to make a significant contribution to high resolution paleoclimatology and improve our understanding of the nature and causes of past climate variability

arctic oscillation signature in a red sea coral we show that the winter time series of the ras umm sidd coral oxygen isotope record from the northern red sea approximately 28 n is linked to the arctic oscillation phenomenon the northern hemisphere s dominant mode of atmospheric variability until now the detection of this mode which is most prominent in winter in proxy climate records was difficult due to the lack of a clear seasonality in most paleoclimatic archives the results suggest that northern red sea corals can provide information about the low frequency variability of the northern hemisphere winter circulation during the pre instrumental period

fluorescent bands in massive corals record centuries of coastal rainfall massive coral colonies on the great barrier reef grow outwards at 5 25 mm yr 1 ref 1 skeletal density varies seasonally in all massive corals from the great barrier reef and an exact temporal record of growth can be obtained by x radiography of appropriately cut sections of the colony2 3 environmental influences on coral growth have been described from such analyses4 6 this is the first report from the skeletons of massive corals of yellow green fluorescent bands which appear under long wave uv light such fluorescence is confined to corals growing within 20 km of the shore and is not present in massive corals from mid and outer shelf reefs of the central great barrier reef region the timing width and intensity of the fluorescent bands correlate strongly with summer monsoonal rainfall and coastal runoff large colonies several centuries old can provide long records of the strength and periodicity of terrestrial runoff to the tropical nearshore environment such records are potentially important to climatology meteorology agriculture civil engineering and management of the great barrier reef

stable oxygen isotopic composition of corals from the gulf of guinea as indicators of periods of extreme precipitation conditions in the sub sahara stable oxygen isotopic analyses of scleractinian coral skeletons from the gulf of guinea in the eastern atlantic reveal that the corals from this region can be used to identify periods of severe drought and above average precipitation in sub sahara africa data presented in this paper show an inverse correlation between precipitation in the sahel and the 18 o values of a coral skeletons of the species siderastrea spp collected from the island of principe in the gulf of guinea this is opposite to the correlation expected as previous work has suggested that higher sea surface temperatures occur in the gulf of guinea during periods of low rainfall in the sahel such an association would lead to a positive correlation between sahel precipitation and skeletal 18 o the explanation for the observed inverse correlation is that the salinity of the gulf of guinea is strongly influenced by the outflow from the niger and congo rivers these periods of high freshwater input also correlate with periods of higher rainfall in the sub sahara and therefore affect the 18 o values of the coral skeleton the correlation between 18 o values of the coral skeleton and temperature in the northern subtropical atlantic ocean r 0 34 the magnitude of the dipole r 0 45 and the latitudinal position of the intertropical convergence zone r 0 37 illustrate that the 18 o values in the coral skeleton reflect climate dynamics of the region that affect the precipitation patterns in sub sahara africa

a high resolution sr ca and δ18o coral record from the great barrier reef australia and the 1982 1983 el nino abstract a high resolution near weekly sr ca and oxygen isotopic record is presented for a coral from the pandora reef in the great barrier reef gbr of australia during the period 1978 to 1984 the records are well correlated except for periods of high rainfall when river runoff has significantly modified the 18o value of seawater using the sr ca temperature calibration of de villiers et al 1994 the sr ca records exhibit seasonally controlled cyclical sst sea surface temperature variations of from 21 to 28 c during the very strong el nino of 1982 1983 the sr ca systematics indicate a sharp drop in the winter sst to 18 5 c this represents a temperature anomaly of 3 c which is approximately twice that given by the 18o variations suggesting an 2 amplification of the anomaly by the sr ca system possibly due to the increasing dominance of inorganically controlled aragoniteseawater fractionation the oxygen isotopic systematics show the combined effects of both temperature and changing seawater 18o values the latter reflecting the influx of 18o depleted runoff during periods of high rainfall due to the extremely low 10 3 sr and ca contents of river run off relative to seawater it is possible to use the sr ca thermometer to calculate temperatures independent of major floods and hence deconvolve the combined effects in the oxygen isotopic record of variable temperature and the 18o value of seawater using this approach it is possible to quantitatively reproduce the volume of runoff from the burdekin river during the periods of major flooding that occurred in early 1979 and 1981 the results of this study demonstrate that the combined use of high resolution sr ca and 18o systematics in scleractinian corals is a powerful tool for providing quantitative constraints on past climate

calibration of stable oxygen isotope signatures in galapagos corals a 2 year 1993 1994 study was conducted in the galapagos islands ecuador to determine the relationship between 18o in skeletal carbonate and sea surface temperature sst in three species of reef building corals pavona clavus pavona gigantea and porites lobata coral samples were grown at 3 10 and 3 m depth at bartolome island champion iisland and urvina bay isabela island respectively hourly measurements of sst and sea surface salinity sss were taken at each site immediately adjacent to colonies which were stained biannually to establish the chronology of growth in addition surface waters were sampled periodically bimonthly to monthly at each site to determine variation in 18o seawater results indicate the mean annual ssts were similar between sites varying from 22 9 c at champion to 23 8 c at urvina bay comparisons of monthly sst averages between instrumental and remote sensing satellite 1 1 grid data show a high correspondence r2 ranging from 0 84 to 0 94 indicating that remote sensing data are useful for interpreting the 18o record in corals when instrumental data are lacking here 18ocoral analyses of eight specimens show that coralline aragonite is a reliable indicator of sst in galapagos in general higher resolution coral sampling year resolved more of the monthly variation in sst up to 97 at a sampling resolution of 1 4 samples per millimeter of linear skeletal growth comparisions of the 18ocoral signal among and between species at the same site showed consistent seasonal patterns of variation closely tracking sst in addition comparisons between sites were highly concordant with some differences reflecting local variation in sst seasonal patterns however were essentially the same over the entire region thus we conclude that the 18ocoral signal from coral skeletons in galapagos can be used to interpret regional changes in sst variation

on the radiocarbon record in banded corals exchange parameters and net transport of 14co2 between atmosphere and surface ocean we have made radiocarbon measurements of banded hermatypic corals from florida belize and the galapagos islands interpretation is presented here of these previously reported results these measurements represent the 14c 12c ratios in dissolved inorganic carbon dioc in the surface ocean waters of the gulf stream and the peru current at the time of coral ring formation a depletion in radiocarbon concentration was observed in coral rings that grew from a d 1900 1952 it was caused by dilution of existing 14c levels with dead co2 from fossil fuel burning the suess effect or se the observed depletion of radiocarbon was greater in corals from the gulf stream 11 than in corals from the peru current 6 a similar trend was observed in the distribution of bomb produced 14c in corals that had grown during the years following a d 1952 the concentration of bomb produced radiocarbon was much higher in corals from temperate regions florida belize hawaiian islands than in corals from tropical regions galapagos islands and canton island a linear relationship appears to exist between the preanthropogenic 14c values and the se values measured in the individual corals because the 14c in corals is derived from two different carbon reservoirs 1 the atmosphere and 2 the subsurface ocean a linear relationship is also observed between the preanthropogenic 14c values and the concentration of bomb produced 14c in the individual corals during a d 1973 the apparent radiocarbon ages of the surface waters in temperate and tropical oceans during the preanthropogenic period range from about 280 to 520 years b p 40 to 69 at all investigated locations it is likely that waters at subsurface depths have the same apparent radiocarbon age of about 670 years b p from the change of oceanic 14c in the surface ocean during post bomb times the approximate annual rate of net input of 14co2 to the ocean waters is calculated to be about 8 of the prevailing 14c difference between atmosphere and ocean from this input and from preanthropogenic 14c values found at each location it can be seen that vertical mixing of water in the peru current is about 3 times greater than that in the gulf stream

interannual and decadal variability of the western pacific sea surface condition for the years 1787 2000 reconstruction based on stable isotope record from a guam coral 1 we present a monthly resolved 213 year stable isotope time series from a coral from guam 13 n 145 e which is located on the northern edge of the western pacific warm pool oxygen isotopic composition of the coral skeleton 18ocoral shows seasonal interannual and decadal variability which documents significant oceanographic changes related to thermal and hydrologic variations in this region the 18ocoral anomaly reflects sea surface temperature sst anomaly and sea surface salinity sss anomaly with significant r values of 0 69 and 0 49 respectively which are strongly linked to oceanographic changes that occur during el nino southern oscillation enso warm and cool phases we identified 46 enso warm el nino and 53 cool phases la nina in the coral record which are consistent with those phases reconstructed by nino 3 4 sst anomaly spectral analyses of the 18ocoral anomaly record for the years 1790 1999 identified significant peaks around 3 to 7 years these results indicate that the guam coral has recorded enso periodicity the 18ocoral anomaly shows decadal variability of 15 to 45 year periodicity with significant shifts 0 2 from warmer to cooler condition and vice versa an accumulative decrease in 18ocoral time series may imply 0 75 c warming of sst and 0 23 freshening of seawater 18o corresponding to a decrease of sss by 0 85 in the northwestern tropical pacific over the last 2 centuries

environmental correlates of hermatypic coral montastrea annularis growth on the east flower gardens bank northwest gulf of mexico time series of annual linear growth increments from 12 montastrea annularis e and s collected at the east flower gardens bank reef in the northwestern gulf of mexico have a common pattern this is best expressed in an index master chronology average by year of the annual percentage deviations from the mean of each coral comparisons with time series of environmental data indicate that coral extension rates vary positively with seasonal february through may4 months surface water temperature and negatively with annual discharge of the atchafalaya river we propose that secular variations of water temperature and other parameters are the major long term controls of coral growth in the area our data do not support the view that sinking of the flower gardens reef caused by catastrophic collapse of the underlying substrate has been a prime influence on the corals

corals at their latitudinal limits laser ablation trace element systematics in porites from shirigai bay japan the rapid analytical technique of laser ablation inductively coupled plasma mass spectrometry la icp ms was used to measure the trace elements b mg sr ba and u in a high latitude coral colony porites lobata taken from shirigai bay japan 32 n a wide range of sea surface temperatures ssts 14 5 28 c and upwelling events influenced this coral cold winter ssts caused a decrease and or cessation of skeletal extension measurements of u ca and sr ca indicate an approximately linear response to ssts above 18 c and a non linear response below 18 c mg ca and b ca measurements both showed annual cycles broadly consistent with sst variations but also exhibited intra annual fluctuations not associated with temperature suggesting that the incorporation of mg and b into the coral skeleton was not simply regulated by temperature it is shown that ba ca ratios provide a proxy for wind induced seasonal upwelling this is inferred from the strong correlations between the strength of zonal winds 1 month prior to the sst minimum and the ba ca maximum secondary upwelling events occurred during the summers of 1982 1987 1991 and 1992 these summers were cooler than average and were associated with el nino southern oscillation events

bomb radiocarbon in the red sea a medium scale gas exchange experiment the history of bomb produced radiocarbon in the surface waters of the red sea and the western gulf of aden was reconstructed from annual growth bands of corals gulf of aden surface water entering the red sea and flowing to the north at the surface of the red sea becomes progressively enriched in bomb sup 14 c by air sea exchange of carbon dioxide with physical oceanographic observations and analysis as the basis of a simple model this progressive northward enrichment can be used to calculate a mean invasionn flux for co sub 2 across the red sea surface the co sub 2 invasion flux so calculated is 8 mol m sup 2 yr with an uncertainty of approximately 2 mol m sup 2 yr when combined with the extensive historical observations of wind speeds in the red sea the calculated co sub 2 invasion flux supports the empirical relationship between co sub 2 invasion and wind speed proposed by other workers sea surface pco sub 2 was measured at seven stations along the length of the red sea in january 1985 these pco sub 2 data show that in midwinter the net flux of co sub 2 across the red sea surface i e the difference between the invasion and evasion fluxes is approximately zero formore the red sea as a whole copyright american geophysical union 1989 less

fault plane solutions of intraplate earthquakes in brazil some constraints on the regional stress field abstract determination of intraplate stress fields is fundamental for a better understanding of the forces driving the plates in the south american plate few earthquakes away from the plate boundaries have been recorded by enough stations to have the nodal planes well determined the fault plane solutions of four recent events in central and northern brazil were determined these solutions were compared with previously determined solutions of other events in central and southeast brazil a statistically reliable estimation of the stress field for all of brazil is not yet possible on the basis of these data near the atlantic coast however the data are compatible with a regional stress field with the maximum compressive stress oriented parallel to the expected direction of ridge push or of south america s absolute plate motion mendiguren and richter 1978 farther to the west the stress field changes the direction of the maximum compressive stress seems to be aligned n s rather than e w almost all earthquakes analysed show reverse or strike slip focal mechanisms one event in central brazil however shows normal faulting thus the stress field in brazil is certainly not uniform and in some areas local sources of stress may predominate over regional fields

sr ca u ca and δ18o records in recent massive corals from bermuda relationships with sea surface temperature abstract high resolution records of sr ca u ca ratios and 18o have been obtained in two recent colonies of massive corals diploria labyrinthiformis from bermuda the three geochemical proxies display regular seasonal variations and are well correlated with each other however some important discrepancies are observed between the two colonies the average seasonal variations of the three geochemical proxies are lower by almost 50 in one of the profiles where the seasonal oscillation also displays a strong asymmetry with narrower summer maxima different calculations are discussed for calibrating sr ca and 18o with sea surface temperatures sst we show that the method using only temperature minima and maxima is slightly more accurate and is also more reliable our results from bermuda corals confirm that the temperature dependency of sr ca u ca and 18o is species dependent as previously shown by others and that vital effects are clearly involved in the geochemical incorporation of trace elements in the coral skeleton finally a simple model involving seasonal variation of the growth rate and a kinetic fractionation related to growth rate is presented to explain the differences between the two bermuda colonies it is shown that these factors may prevent corals from recording the complete temperature seasonality and could be the cause for the discrepancies observed between profiles resulting in significant biases of the sst reconstructions