accretion of a new england u s a salt marsh in response to inlet migration storms and sea level rise sediment accumulation rates were determined at several sites throughout nauset marsh massachusetts u s a a back barrier lagoonal system using feldspar marker horizons to evaluate short term rates 1 to 2 year scales and radiometric techniques to estimate rates over longer time scales 137cs 210pb 14c the barrier spit fronting thespartina dominated study site has a complex geomorphic history of inlet migration and overwash events this study evaluates sediment accumulation rates in relation to inlet migration storm events and sea level rise the marker horizon technique displayed strong temporal and spatial variability in response to storm events and proximity to the inlet sediment accumulation rates of up to 24 mm year 1were recorded in the immediate vicinity of the inlet during a period that included several major coastal storms while feldspar sites remote from the inlet had substantially lower rates trace accumulation to 2 2 mm year 1 during storm free periods accumulation rates did not exceed 6 7 mm year 1 but remained quite variable among sites based on137cs 3 8 to 4 5 mm year 1 and210pb 2 6 to 4 2 mm year 1 radiometric techniques integrating sediment accumulation over decadal time scales the marsh appeared to be keeping pace with the relative rate of sea level rise from 1921 to 1993 of 2 4 mm year 1 at one site the210pb based sedimentation rate and rate of relative sea level rise were nearly similar and peat rhizome analysis revealed thatdistichlis spicatarecently replaced this onces patenssite suggesting that this portion of nauset marsh may be getting wetter thus representing an initial response to wetland submergence horizon markers are useful in evaluating the role of short term events such as storms or inlet migration influencing marsh sedimentation processes however sampling methods that integrate marsh sedimentation over decadal time scales are preferable when evaluating a systems response to sea level rise

the sea level fingerprint of west antarctic collapse recent projections of sea level rise after a future collapse of thewest antarctic ice sheet for example the fourth intergovernmental panel on climate change assessment report assume that meltwater will spread uniformly that is eustatically across the oceans once marine based sectors of the west antarctic are filled a largely neglected 1977 study predicted that peak values would be 20 higher than the eustatic in the north pacific and 5 to 10 higher along the u s coastline we show with use of a state of the art theory that the sea level rise in excess of the eustatic value will be two to three times higher than previously predicted for u s coastal sites

a flexible approach to assessing synchroneity of past events using bayesian reconstructions of sedimentation history the dating of depths in two or more cores is frequently followed by a study of the synchroneity or otherwise of events reflected in the cores the difficulties most frequently encountered are a determining precisely the depths associated with the events and b determining the ages associated with the depths there has been much progress in recent years in developing tools for the study of uncertainties in establishing chronologies this has not yet been matched by similar progress in modelling event depth relationships this paper proposes a simple and flexible approach showing how uncertain events can be married to uncertain chronologies difficulties in studying event depth age relationships typically involve a confounding of two different problems first what exactly do we mean by an event a point in history a single depth in the core corresponding to a single time or a depth time range sometimes event is in fact a shorthand for a space time process do the data reflect more than one type of event process this can reflect vagueness in definition second what are the sources and implications of the uncertainties here we illustrate the issues involved by examination of several features seen in north european holocene pollen records the alnus rise is regarded as a diachronous early holocene event in contrast the ulmus decline is widely seen as a near synchronous event in the mid holocene the third feature we examine is the interval between the ulmus decline and the first occurrence of cerealia type pollen the evidence for these events lies in cores of lake sediment from which are determined a the proportions of pollen at many depths and b radiocarbon age estimates from usually fewer depths for this illustration we focus on six sites we draw attention to a new and flexible method implemented in the free r software package bchron haslett j parnell a 2008 a simple monotone process with application to radiocarbon dated depth chronologies journal of the royal statistical society series c 57 4 399 418 for the establishment of the uncertainties surrounding the dating of samples in such cores we illustrate its flexibility by assessing the synchroneity of past events

onset of recent rapid sea level rise in the western atlantic ocean a high resolution record of sea level change spanning the past 1000 years is derived from foraminiferal and chronological analyses of a 2 m thick salt marsh peat sequence at chezzetcook nova scotia canada former mean tide level positions are reconstructed with a precision of 0 055 m using a transfer function derived from distributions of modern salt marsh foraminifera our age model for the core section older than 300 years is based on 19 ams 14c ages and takes into account the individual probability distributions of calibrated radiocarbon ages the past 300 years is dated by pollen and the isotopes 206pb 207pb 210pb 137cs and 241am between ad 1000 and ad 1800 relative sea level rose at a mean rate of 17 cm per century apparent pre industrial rises of sea level dated at ad 1500 1550 and ad 1700 1800 cannot be clearly distinguished when radiocarbon age errors are taken into account furthermore they may be an artefact of fluctuations in atmospheric 14c production in the 19th century sea level rose at a mean rate of 1 6 mm yr between ad 1900 and ad 1920 sea level rise accelerated to the modern mean rate of 3 2 mm yr this acceleration corresponds in time with global temperature rise and may therefore be associated with recent global warming 2005 elsevier ltd all rights reserved

coupling instrumental and geological records of sea level change evidence from southern new england of an increase in the rate of sea level rise in the late 19th century 1 we construct a high resolution relative sea level record for the past 700 years by dating basal salt marsh peat samples above a glacial erratic in an eastern connecticut salt marsh to test whether or not the apparent recent acceleration in the rate of sea level rise slr is coeval with climate warming the data reveal an average slr rate of 1 0 0 2 mm year from about 1300 to 1850 a d coupling of the regional tide gauge data 1856 to present with this marsh based record indicates that the nearly three fold increase in the regional rate of slr to modern levels likely occurred in the later half of the 19th century thus the timing of the observed slr rate increase is coincident with the onset of climate warming indicating a possible link between historic slr increases and recent temperature increases

the use of jadammina macrescens brady and balticammina pseudomacrescens bronnimann lutze and whittaker protozoa foraminiferida as sea level indicators in studies of foraminiferal distributions in saltmarshes in new england and atlantic canada balticammina pseudomacrescens and jadammina macrescens have formerly been grouped as trochammina macrescens this study recognises them as distinct species and shows that they have significantly different distributions on the surface of saltmarshes in maine here relative abundances of j macrescens correlate with tidal elevation r2 0 55 p 0 00 whereas those of b pseudomacrescens do not r2 0 03 p 0 34 therefore j macrescens is a better sea level indicator in maine marshes than b pseudomacrescens in menunketesuck river marsh connecticut a clear vertical zonation of saltmarsh foraminifera is absent which hinders interpretation of fossil data this study shows that in maine separating b pseudomacrescens and j macrescens in counts of fossil data facilitates the detection of transgressional and regressional events in the biostratigraphical record and hence the reconstruction of local sea level histories regional variability between northern and southern new england saltmarshes necessitates the establishment of local reference sets of modern analogue data to aid palaeoecological interpretations

structure of a low level jet over lower cook inlet alaska abstract during february 1982 a noaa research aircraft investigated a cold low level jet blowing from a gap between mountain ranges on line west side of cook inlet alaska the jet blew 200 km southeastward across cook inlet between the kenai peninsula and the kodiak archipelago passing into the gulf of alaska where it merged with the large scale marine wind field measurement commenced 35 km downstream of the seaward end of the gap the jet s internal boundary layer accelerated by 5 and grew 20 in depth for 50 km thereafter wind speed and boundary layer depth were nearly constant for the next 100 km the strongest winds 20 m s 1 at a height of 80 m were observed on the south side of the jet s thermal axis and 90 km downstream from the coast budget analyses reveal that the down gradient acceleration within the jet was principally opposed by surface friction and the cold air advection was balanced by a strong upward directed sensible heat flux from cook inlet and entrainment of warmer air from

rapid wetland expansion during european settlement and its implication for marsh survival under modern sediment delivery rates fluctuations in sea level rise rates are thought to dominate the formation and evolution of coastal wetlands here we demonstrate a contrasting scenario in which land use related changes in sediment delivery rates drive the formation of expansive marshland and vegetation feedbacks maintain their morphology despite recent sediment supply reduction stratigraphic analysis and radiocarbon dating in the plum island estuary massachusetts united states suggest that salt marshes expanded rapidly during the eighteenth and nineteenth centuries due to increased rates of sediment delivery following deforestation associated with european settlement numerical modeling coupled with the stratigraphic observations suggests that existing marshland could survive but not form under the low suspended sediment concentrations observed in the estuary today these results suggest that many of the expansive marshes that characterize the modern north american coast are metastable relicts of high nineteenth century sediment delivery rates and that recent observations of degradation may represent a slow return to pre settlement marsh extent in contrast to ecosystem management practices in which restoring pre anthropogenic conditions is seen as a way to increase ecosystem services our results suggest that widespread efforts to restore valuable coastal wetlands actually prevent some systems from returning to a natural state

relative sea level rise and climate change over the last 1500 years we constructed a detailed relative sea level rise curve for the last 1500 years using a novel approach i e charting the rate of relative sea level rise using microfaunal and geochemical data from a coastal salt marsh sequence clinton ct usa the composition of benthic foraminiferal assemblages and the iron abundance in peats were used to describe shifts in marsh environment through time quantitatively the resulting sea level rise curve with age control from 14c dating and the onset of anthropogenic metal pollution shows strong increases in the rate of relative sea level rise during modern global warming since the late nineteenth century but not during the little climate optimum ad 1000 1300 there was virtually no rise in sea level during the little ice age ad 1400 1700 most of the relative sea level rise over the last 1200 years in clinton appears to have occurred during two warm episodes that jointly lasted less than 600 years changes from slow to fast rates of relative sea level rise apparently occurred over periods of only a few decades we suggest that changes in ocean circulation could contribute to the sudden increases in the rate of relative sea level rise along the northeastern usa seaboard relative sea level rise in that area is currently faster than the worldwide average which may result partially from an ocean surface effect caused by hydrodynamics our data show no unequivocal correlation between warm periods on a decaal to centennial time scale and accelerated sea level rise one period of acclerated sea level rise may have occurred between about ad 1200 and 1450 which was the transition for the little climate optimum to the little ice age i e a period of cooling at least in northwestern europe local changes in tidal range might also have contributed to this apparent increase in the rate of relative sea level however the second period of accelerated sea level rise occurred during the period of modern global warming that started at the end of the last century

medieval warming little ice age and european impact on the environment during the last millennium in the lower hudson valley new york usa establishing natural climate variability becomes particularly important in large urban areas in anticipation of droughts we present a welldated bi decadal record of vegetation climate land use and fire frequency from a tidal marsh in the hudson river estuary the classic medieval warm period is evident through striking increases in charcoal and pinus dominance from 800 1300 a d paralleling paleorecords southward along the atlantic seaboard higher inputs of inorganic sediment during this interval suggest increased watershed erosion during drought conditions the presence of the little ice age ensues with increases in picea and tsuga coupled with increasing organic percentages due to cooler moister conditions european impact is manifested by a decline in arboreal pollen due to land clearance increased weedy plant cover i e ambrosia plantago and rumex and an increase in inorganic particles to the watershed

scale considerations in using diatoms as indicators of sea level change lessons from alaska this paper assesses variations in quantitative reconstructions of late holocene relative sea level rsl change arising from using modern diatom datasets from different spatial scales applied to case studies from alaska we investigate the implications of model choice in transfer functions using local sub regional and regional scale modern training sets and produce recommendations on the creation and selection of modern datasets for reconstructing rsl change over holocene timescales in tidal marsh environments comparable with those in alaska we show that regional modern training sets perform best in terms of providing fossil samples with good modern analogues and in producing reconstructions that most closely match observations where these are available local training sets are frequently insufficient to provide fossil samples with good modern analogues and may over estimate the precision of rsl reconstructions this is particularly apparent when reconstructing rsl change for periods beyond the last century for reconstructing rsl change we recommend using regional modern training sets enhanced by local samples

surface distributions of salt marsh foraminifera from connecticut usa modern analogues for high resolution sea level studies abstract salt marsh foraminifera are routinely used as sea level indicators since their vertical distribution is closely linked with elevation relative to the tidal frame the precise nature of these relationships is variable in time and space and the accuracy of sea level reconstructions depends upon the selection of appropriate modern analogues that reliably reflect past fauna environment associations the marshes of connecticut usa are sites of ongoing research seeking to produce high resolution records of sea level change yet little published data regarding their modern foraminiferal distributions exist this paper presents new surface foraminiferal data from three connecticut salt marshes and evaluates their suitability as modern analogues for past sea level changes the results indicate that significant intra and inter site variability between these marshes and those of neighbouring states exists as a consequence of this the extrapolation of fauna environment relationships developed from marshes with different hydrographic physiographic vegetative or climatic characteristics may produce erroneous reconstructions even when adjusted for variations in tidal range these errors are potentially greatest if single indicator species are used since the relative abundance of individual taxa does not vary consistently with elevation even in high marsh environments from the same site whilst cluster analysis demonstrates that foraminiferal assemblages from connecticut are vertically zoned with respect to mean high water mhw the composition elevation and height range of these zones is variable between sites this spatial heterogeneity results in reconstructions of relatively low and variable precision that restricts their utility in high resolution sea level research new studies seeking to distil decimetre scale changes in relative sea level will need to employ quantitative methods capable of combining multi site information to develop fauna environment relationships that capture this spatial variability reconstructions will be most precise when employing local foraminiferal distributions but may require the collection of additional modern analogue samples from other regions when the extant foraminiferal population of a site differs in composition from its sub fossil counterpart

organic carbon isotope systematics of coastal marshes abstract measurements of nitrogen organic carbon and 13c are presented forspartina dominated marsh sediments from a mineral marsh in sw netherlands and from a peaty marsh in massachusetts u s a 13c of organic carbon in the peaty marsh sediments is similar to that ofspartinamaterial whereas that in mineral marshes is depleted by 9 12 it is argued that this depletion in 13c of organic matter in marsh sediments is due to trapping of allochthonous organic matter which is depleted in13c the isotopic composition and concentration of organic carbon are used in a simple mass balance to constrain the amount of plant material accumulating in marsh sediments i e in terms of the so called net ecosystem production net ecosystem production 2 100 g c m 2year 1 is a small fraction 1 5 of plant production 2000 g c m 2year 1 this small amount of plant material being preserved is nevertheless sufficient to support marsh accretion rates similar to the rate of sea level rise

anthropogenic versus natural control on trace element and sr nd pb isotope stratigraphy in peat sediments of southeast florida usa 1500 ad to present abstract analysis of a well dated peat core from blue cypress marsh bcm provides a detailed record of natural and anthropogenic factors that controlled the geochemical cycles of a number of trace elements in florida over the last five centuries the trace elements were divided into natural and anthropogenic groups using concentration trends from the bottom to the top of the core the natural group includes li sc cr co ga ge zr nb cs ba hf y ta th and ree rare earth elements these elements show similar concentrations throughout the core indicating that changes in human activities after european arrival in the new world did not affect their geochemical cycles the anthropogenic group includes pb cu zn v sb sn bi and cd upcore enrichment of these elements indicates enhancement by anthropogenic activities from the early 1500s to present fluxes of the anthropogenic metals to the marsh increased significantly with modern accumulation rates several fold e g v to hundreds of times e g zn greater than pre colonial rates the dominant input mechanism for trace elements from both groups to the marsh has been atmospheric deposition atmospheric input of a number of the elements including the anthropogenic metals was dominated by local sources during the last century for several elements long distant transport may be important for instance ree and nd isotopes provide evidence for long range atmospheric transport dominated by saharan dust the greatest increase in flux of the anthropogenic metals occurred during the 20th century and was caused by changes in the chemical composition of atmospheric deposition entering the marsh increased atmospheric inputs were a consequence of several anthropogenic activities including fossil fuel combustion coal and oil agricultural activities and quarrying and mining operations pb and v exhibit similar trends with peak accumulation rates in 1970 the principal anthropogenic source of v is oil combustion the decline in v accumulation after 1970 in the bcm peat corresponds to the introduction of low sulfur fuels and the change from heavy to distilled oils since the 1970s after the 1920s pb distribution in the peat follows closely the history of alkyl lead consumption in the us which peaked in the 1970s pb isotopes support this inference and furthermore record changes in the ore sources used to produce leaded gasoline idaho ores dominated the peat pb isotope record until the 1960s followed by pb from mississippi valley type deposits from the 1960s to the 1980s enhanced fluxes of cu zn cd sn sb bi and to some extent ni during the last century are likely also related to fossil fuel combustion local agricultural activities may also have influenced the geochemical cycles of cu and zn the peat record shows enhanced u accumulation during the last century possibly related to phosphate mining in western florida sr isotopes in the peat core also reflect anthropogenic influence the 87sr 86sr ratio decreases from natural background values in the basal part of the core to lower values in the upper part of the core the sr isotope shift is probably related to quarrying operations in florida and marks the first time an anthropogenic signal has been detected using the sr isotope record in a peat core

reassessing transfer function performance in sea level reconstruction based on benthic salt marsh foraminifera from the atlantic coast of ne north america abstract the need to increase the number and distribution of sea level records spanning the last few hundred years has led to particular interest in developing high precision geologically based sea level reconstructions that capture decimetre and multi decadal scale changes transfer functions for tide level are statistical tools that quantify the vertical relationship between inter tidal microfossils and elevation within the tidal frame and their use in sea level reconstruction is growing in popularity whilst a range of sampling strategies dataset qualities and underlying statistical models have been used in transfer function development all variants share the common requirement of accurately extracting precise species elevation relationships from surface data and reliably applying these to fossil assemblages to infer past conditions we present surface foraminiferal data from six transects sampled at three sites spanning a large latitudinal range extending from newfoundland canada to north carolina usa these data demonstrate that significant spatial differences exist within the high marsh foraminiferal assemblages commonly used to reconstruct past relative sea level rsl we standardise these data to account for inter site differences in tidal range using several variants of the standardised water level index swli of horton et al 1999b and show that the best performance is achieved by using the highest occurrence of foraminifera as the upper tidal datum level the standardised surface foraminiferal data are used to develop a suite of foraminiferal transfer functions for tide level which are then applied to fossil assemblages from two sediment cores to reconstruct palaeomarsh surface elevation we highlight the manner in which species elevation relationships are extracted and modified during transfer function development and the impacts that choices in dataset composition and transfer function type have on the resulting reconstructions our results graphically illustrate the importance of these choices and the impacts of temporal and spatial variability in foraminiferal distributions none of which are adequately represented or discernible from the standard summary statistics of performance that commonly accompany transfer function reconstructions we conclude that a more explicit treatment of the transfer function development process is required to support the growing body of precise rsl reconstructions that are now appearing in the literature to that end we make the following four recommendations for a framework to assist in transfer function development that will allow better record inter comparison and minimise the potential for producing precise but ultimately inaccurate reconstructions 1 sampling for surface data should focus on capturing complete species response curves rather than simply compiling modern analogues for fossil material 2 the similarity between the surface assemblages used to produce transfer functions and the fossil assemblages to which they are applied should be better quantified using a range of statistical approaches and must accompany any reconstruction 3 where modern analogues are lacking in local surface assemblages data from additional sites should be added with selection based on fulfilling the requirements of the previous two recommendations the manner in which individual species optima are combined to produce a composite optimum and the extent to which this provides a reasonable representation of the surface data should also be documented 4 the application of wa pls component 2 and higher cannot be justified solely on the grounds of increased performance measures e g r2jack and rmsep and if applied the pattern of optima updates should be used to highlight species that may distort reconstructions

a review of coastal palaeoclimate and relative sea level reconstructions using δ13c and c n ratios in organic material holocene reconstructions of relative sea level rsl and environmental change in the coastal zone have become progressively more numerous since the importance of assessing possible future sea level rises has become apparent traditionally this has been achieved using a combination of biological and physical indicators e g pollen diatoms foraminifera grain size etc in some circumstances microfossils can be rare or absent from holocene sediments and in these cases carbon isotope ratios 13c and organic carbon to total nitrogen ratios c n can be used because they have the potential to provide information as to the origin of organic material preserved in coastal environments the distinction in 13c and c n of the various sources of carbon to estuarine sediments has led to its wide use as a tracer of carbon pathways and storage in estuaries more recently these techniques have been applied to holocene sediments to decipher changes in palaeocoastal environments and thus position relative to sea level and or palaeoriver discharge which have direct relevance to palaeoclimate this paper reviews the studies that have utilised this technique and explores examples from a wide range of coastal environments saltmarshes estuaries lagoons isolation basins and fjords it also discusses the potential alteration of geochemical signatures as a result of decompositional processes organic matter decomposition has been shown to change sediment 13c and c n values and thus an understanding of the processes involved is necessary in order to have confidence in the palaeoenvironmental interpretation of holocene 13c and c n decompositional shifts in c n and particularly 13c can occur over a relatively short time period however it is the direction of change in 13c and c n rather than absolute values that is key for interpreting changes in relative sea level and thus such changes are commonly preserved

c3 c4 variations in salt marsh sediments an application of compound specific isotopic analysis of lipid biomarkers to late holocene paleoenvironmental research in salt marshes bulk carbon isotope values reflect organic matter contributions not only from salt marsh plants but also from algal and bacterial inputs as well as allochthonous terrestrial organic matter in the present study compound specific isotope analysis was applied to a core and modern plant samples collected from a machiasport maine salt marsh we sampled 10 plant species common to the marsh including spartina alterniftora spartina patens juncus gerardi solidago sempervirens salicornia europa potentilla anserina atriplex patula plantago maritima suaeda maritima and limonium nashii isolation of two n alkanes c 27 and c 29 present in marsh plant samples allowed for the reconstruction of past plant communities present in the cored deposits for the c 27 and c 29 homologues there is a 3 10 separation in carbon isotopic composition between c3 and c4 species carbon isotopic values down core show a transition from a c4 dominated plant community to a c3 dominated community attributable to the migration of lower marsh zones onto brackish freshwater marsh zones during a late holocene relative sea level rise the two homologues used have the potential to provide paleoenvironmental information in future core work where the sea level variable will be controlled

architecture of collapsed paleocave reservoirs it is important to investigate the architecture of collapsed paleocave reservoirs at interwell scales in outcrops because reservoir heterogeneities cannot be adequately characterized by cores and log correlation sections a 3000 foot long quarry wall of ellenburger strata in central texas displays the lithologic and pore network heterogeneities at typical well spacings 1300 to 2600 feet the quarry wall exposes the transition from stratified host rock into a complex collapsed paleocave system showing several developmental episodes this paleocave system has over 2600 feet of laterally continuous chaotic breccias the dimensions of these breccias are similar as to what is imaged by 3 d seismic over paleocave reservoirs collapsed paleocave reservoirs are not single collapsed passages of tens of feet across but are homogenized collapsed cave systems hundreds to several thousand feet across this concept of scale is very important because collapsed paleocave systems offer larger exploration targets than individual cave passages collapsed paleocave systems are complex because they are the homogenization of chaotic breccias and cave sediment fill from passages chambers and shafts and of crackle breccias from roof and wall rock and pillars pore networks are associated with chaotic breakdown breccias cave roof and wall crackle breccias and or clastic sediment fill strong heterogeneity within a collapsed paleocave system should bemore expected lateral and vertical changes in collapsed paleocave related facies have the strongest effect on reservoir heterogeneity and quality within individual facies there can be distinct reservoir quality variation such as between the cave sediment fill and associated blocks tectonic fractures however can interconnect the highly variable pore networks within a collapsed paleocave reservoir less

middle to late holocene fluctuations of c3 and c4 vegetation in a northern new england salt marsh sprague marsh phippsburg maine abstract a 3 1 m sediment core was analyzed for stable carbon isotope composition of organic matter and higher plant leaf wax hplw lipid biomarkers to determine holocene shifts in c 3 higher high marsh and c 4 low and or high marsh plant deposition at the sprague river salt marsh phippsburg maine the carbon isotope composition of the bulk sediment and the hplw parallel each other throughout most of the core suggesting that terrestrial plants are an important source of organic matter to the sediments and diagenetic alteration of the bulk sediments is minimal the current salt marsh began to form 2500 cal yr bp low and or high c 4 marsh plants dominated deposition at 2000 cal yr bp 700 cal yr bp and for the last 200 cal yr bp expansion of higher high marsh c 3 plants occurred at 1300 and 600 cal yr bp these major vegetation shifts result from a combination of changes in relative sea level rise and sediment accumulation rates average annual carbon sequestration rates for the last 2500 years approximate 40 g c yr 1 m 2 and are in strong agreement with other values published for the gulf of maine given that maine salt marshes cover an area of 79 km 2 they represent an important component of the terrestrial carbon sink more detailed isotopic and age records from a network of sediment cores at sprague marsh are needed to truly evaluate the long term changes in salt marsh plant communities and the impact of more recent human activity including global warming on salt marsh vegetation

a new projection of sea level change in response to collapse of marine sectors of the antarctic ice sheet we present gravitationally self consistent predictions of sea level change that would follow the disappearance of either the west antarctic ice sheet wais or marine sectors of the east antarctic ice sheet eais our predictions are based on a state of the art pseudo spectral sea level algorithm that incorporates deformational gravitational and rotational effects on sea level as well as the migration of shorelines due to both local sea level variations and changes in the extent of marine based ice cover if we define the effective eustatic value eev as the geographically uniform rise in sea level once all marine based sectors have been filled with water then we find that some locations can experience a sea level rise that is 40 per cent higher than the eev this enhancement is due to the migration of water away from the zone of melting in response to the loss of gravitational attraction towards the ice sheet load self attraction the expulsion of water from marine areas as these regions rebound due to the unloading and the feedback into sea level of a contemporaneous perturbation in earth rotation in the wais case this peak enhancement is twice the value predicted in a previous projection that did not include expulsion of water from exposed marine sectors of the west antarctic or rotational feedback the peak enhancements occur over the coasts of the united states and in the indian ocean in the wais melt scenario and over the south atlantic and northwest pacific in the eais scenario we conclude that accurate projections of the sea level hazard associated with ongoing global warming should be based on a theory that includes the complete suite of physical processes described above

contrasting records of sea level change in the eastern and western north atlantic during the last 300 years we present a new 300 year sea level reconstruction from a salt marsh on the isle of wight central english channel uk that we compare to other salt marsh and long tide gauge records to examine spatial and temporal variability in sea level change in the north atlantic our new reconstruction identifies an overall rise in relative sea level rsl of c 0 30 m since the start of the eighteenth century at a rate of 0 9 0 3 mmyr 1 error in variables changepoint analysis indicates that there is no statistically significant deviation from a constant rate within the dataset the reconstruction is broadly comparable to other tide gauge and salt marsh records from the european atlantic demonstrating coherence in sea level in this region over the last 150 300 years in contrast we identify significant differences in the rate and timing of rsl with records from the east coast of north america the absence of a strong late 19th early 20th century rsl acceleration contrasts with that recorded in salt marsh sediments along the eastern usa coastline in particular in a well dated and precise sea level reconstruction from north carolina this suggests that this part of the north carolina sea level record represents a regionally specific sea level acceleration this is significant because the north carolina record has been used as if it were globally representative within semi empirical parameterisations of past and future sea level change we conclude that regional scale differences of sea level change highlight the value of using several regionally representative rsl records when calibrating and testing semi empirical models of sea level against palaeo records this is because by using records that potentially over estimate sea level rise in the past such models risk over estimating sea level rise in the future

sea level climate correlation during the past 1400 yr we present a new mean high water curve for hammock river marsh clinton connecticut obtained by improving the age model for an existing record of relative marsh elevation based on foraminiferal analysis of a 1 8 m long peat core unlike the earlier curve the new curve confirms trend changes in mean high water rise during the past 1400 yr as noted for salt marshes 15 km farther west suggesting a regional cause these trend changes and century scale mean high water variations in the clinton record correlate positively with large scale regional variations in sea surface and summer air temperature indicating a link between sea level and the climate ocean system on the basis of the clinton mean high water curve we conclude that real sea level oscillated centimeters to decimeters on a century time scale over the past 1400 yr was 25 25 cm higher ca a d 1050 medieval warm period than ca a d 1650 little ice age and rose at a mean rate of 1 mm yr 1 over the past 350 yr there was little or no rise during the cool 1800s

high resolution numerical modeling of tides in the western atlantic gulf of mexico and caribbean sea during the holocene 1 tidal constituents and datums are computed on a high resolution grid of the northwestern atlantic ocean including the gulf of mexico and the caribbean sea a global model is used to determine tidal parameters on a grid with a nominal resolution of 800 800 the global model includes self attraction and loading drag in shallow marginal seas and internal tide drag in the deep ocean simulations are performed at 1000 year intervals during the holocene 10 000 calibrated years before present 10 ka in combination with changes in bathymetry and coastline location derived from a glacial isostatic adjustment model the global model results are then used to force a regional barotropic tidal model the regional model uses an unstructured finite element grid with very high resolution at the coastline the model results reveal significant variations in tidal constituent amplitudes throughout the holocene in the northwestern atlantic semi diurnal components show a strong amplification at around 9 ka while in the gulf of mexico the response is much more muted variations in diurnal tidal parameters are found to be less significant than semi diurnal parameters throughout the model domain changes in tidal range of great relevance to changes in relative sea level rsl are also investigated throughout the holocene the overall structure is similar to the patterns observed in the m2 tide with peak increases of 200 300 relative to present day being observed along the east coast of the united states from 9 to 8 ka finally the high spatial resolution of the regional model allows for the investigation of tidal changes at spatial scales e g individual bays much smaller than in previous studies

lead concentrations and isotopes in corals and water near bermuda 1780 2000 abstract the history of the oceanic anthropogenic lead pb transient in the north atlantic ocean for the past 220 yr is documented here from measurements of pb concentration and isotope ratios from annually banded corals that grew in coastal seawaters near bermuda and from seawater samples collected during the last 20 yr of the 20th century anthropogenic pb emissions in this area have been dominated by the industrialization of north america beginning in the 1840s the introduction of leaded gasoline beginning in the 1920s and its phase out that began in the mid 1970s the phase out of leaded gasoline was largely completed by the late 1990s coral pb concentrations occur at a constant low level of about 5 nmol pb mol ca 15 pmol kg in seawater from the late 1700s to 1850 from 1850 to 1900 there is a small increase rising to a plateau at 25 nmol pb mol ca 80 pmol kg in seawater in the 1930s until the late 1940s at which point pb concentrations rapidly increase to 60 nmol pb mol ca 200 pmol kg in seawater in the mid 1970s pb began to decline to 25 nmol pb ca 40 pmol kg in seawater by the end of the 20th century comparable to levels occurring in the early 20th century pb isotope ratios pb i r show maximum 206pb 207pb 1 21 and 208pb 207pb 2 49 in the middle of the 19th century we conclude that this signal is a reflection of the early dominance of upper mississippi valley pb ore in the united states as previously seen in the estuarine sediments of rhode island after 1900 pb i r decrease only slightly until the 1960s when there is a significant local maximum in the 1970s to 206pb 207pb 1 19 and 208pb 207pb 2 45 as low pb i r sources were phased out in the united states then as us leaded gasoline utilization decreased more rapidly than european pb gas utilization which has lower pb i r western north atlantic pb i r decreased to 206pb 207pb 1 17 and 208pb 207pb 2 44 their lowest values in the past two centuries

the application of local and regional transfer functions to the reconstruction of holocene sea levels north norfolk england foraminiferal assemblages from thornham and brancaster marshes norfolk uk illustrate statistically significant relationship with elevation with respect to the tidal frame we develop local data from thornham and brancaster marshes and regional data from thornham and brancaster marshes combined with those from 11 other sites around the uk predictive foraminifera based transfer functions to reconstruct former sea levels from a holocene sediment sequence from holkham north norfolk uk the two transfer functions produce similar patterns of tidal elevation change during the holocene the vertical error ranges of the local transfer function are smaller than those of the regional transfer function although the difference 0 09 m is not significant when compared to other factors affecting the reconstructed elevation the value of the reconstructed elevations also differ between the two transfer functions by up to 0 43 m and this is primarily due to the lack of modern analogues in the local transfer function we conclude that the reconstructions derived from the regional transfer function are more reliable than those of the local transfer function since the latter achieves its slight increase in precision at the expense of a significant decrease in predictive power the regional transfer function is used to construct a relative sea level curve from fossil assemblages within a sediment core from north norfolk uk these results are consistent with existing sea level data and geophysical model predictions and illustrate the utility of the foraminifera based transfer function approach

a sea level rise curve from guilford connecticut usa abstract high resolution stratigraphic studies based on sediment chemistry lithology macroflora and benthic foraminiferal assemblages in three peat cores from coastal salt marshes at guilford connecticut show that coastal marshes are ephemeral environments marsh wide environmental variations were common and century long episodes of relative submergence alternated with emergence despite about 2 m of relative sea level rise rslr in connecticut over the last 1500 years the marshes have expanded both landwards and seawards and marsh accretion has been outpaced only marginally by rslr we used radiocarbon dating and the level of anthropogenic markers metal pollution as dated with 210 pb in the cores for age control for most of the last 1000 years the rate of rslr was between 1 3 and 1 8 mm yr but over the last 300 400 years it increased to 2 9 3 3 mm yr and has been faster than the accretion rate especially in the middle marsh the net submergence rate or submergence index ratio of the rate of rslr and marsh accretion rate averaged about 1 15 over the last 1000 years and increased to about 1 5 over the last 200 years the rate of rslr was very sluggish during the early part of the little ice age but we found a slightly higher rate during the little climate optimum this excursion is close to the noise level however the most significant observation is that rslr increased strongly around a d 1650 the onset of this acceleration falls in the middle to end of the little ice age and thus preceded the period of modern global warming that started late last century and that has been tentatively correlated with anthropogenic emissions of greenhouse gases

rapid sea level rise in the gulf of maine usa since ad 1800 two sea level records from salt marshes in coastal maine are derived from foraminiferal analyses and ams 14 c 210 pb 137 cs and pollen chronology both records cover the period from ad 800 until the present and show corresponding patterns of sea level change when corrected for trends which could accommodate millennial scale isostatic adjustments the records provide a detailed sea level chronology for the last few centuries and thus link the instrumental tide gauge record with the long term geological record of sea level change results show that sea level was relatively stable between ad 800 and 1300 and reached a lowstand around ad 1800 which was preceded by an oscillation in the eighteenth century since ad 1800 sea levels in the gulf of maine have risen by 0 3 0 4 m the onset of this rise corresponds with regional climatic warming and could be interpreted as thermal expansion of the gulf of maine and north atlantic sea surface sea level rise possibly slowed temporarily during the mid nineteenth century but twentieth century rates are unprecedented in the last millennium and correspond with hemispheric warming

does the mid atlantic united states sea level acceleration hot spot reflect ocean dynamic variability 1 to test a hypothesized faster than global sea level acceleration along the mid atlantic united states i construct a gaussian process model that decomposes tide gauge data into short term variability and longer term trends and into globally coherent regionally coherent and local components while tide gauge records indicate a faster than global increase in the rate of mid atlantic u s sea level rise beginning 1975 this acceleration could reflect either the start of a long term trend or ocean dynamic variability the acceleration will need to continue for 2 decades before the rate of increase of the sea level difference between the mid atlantic and southeastern u s can be judged as very likely unprecedented by 20th century standards however the difference is correlated with the atlantic multidecadal oscillation north atlantic oscillation and gulf stream north wall indices all of which are currently within the range of past variability

recent global sea level acceleration started over 200 years ago 1 we present a reconstruction of global sea level gsl since 1700 calculated from tide gauge records and analyse the evolution of global sea level acceleration during the past 300 years we provide observational evidence that sea level acceleration up to the present has been about 0 01 mm yr2 and appears to have started at the end of the 18th century sea level rose by 6 cm during the 19th century and 19 cm in the 20th century superimposed on the long term acceleration are quasi periodic fluctuations with a period of about 60 years if the conditions that established the acceleration continue then sea level will rise 34 cm over the 21st century long time constants in oceanic heat content and increased ice sheet melting imply that the latest intergovernmental panel on climate change ipcc estimates of sea level are probably too low

relative sea level change in connecticut usa during the last 2200 yrs we produced a relative sea level rsl reconstruction from connecticut usa spanning the last 2200 yrs that is free from the influence of sediment compaction the reconstruction used a suite of vertically and laterally ordered sediment samples 2 cm above bedrock that were collected by excavating a trench along an evenly sloped bedrock surface paleomarsh elevation was reconstructed using a regional scale transfer function trained on the modern distribution of foraminifera on long island sound salt marshes and supported by bulk sediment 13c measurements the history of sediment accumulation was estimated using an age elevation model constrained by radiocarbon dates and recognition of pollution horizons of known age the rsl reconstruction was combined with regional tide gauge measurements spanning the last 150 yrs before being quantitatively analyzed using an error in variables integrated gaussian process model to identify sea level trends with formal and appropriate treatment of uncertainty and the temporal distribution of data rsl rise was stable 1 mm yr from 200 bce to 1000 ce slowed to a minimum rate of rise 0 41 mm yr at 1400 ce and then accelerated continuously to reach a current rate of 3 2 mm yr which is the fastest century scale rate of the last 2200 yrs change point analysis identified that modern rates of rise in connecticut began at 1850 1886 ce this timing is synchronous with changes recorded at other sites on the u s atlantic coast and is likely the local expression of a global sea level change earlier sea level trends show coherence north of cape hatteras that are contrasted with southern sites this pattern may represent centennial scale variability in the position and or strength of the gulf stream comparison of the new record to three existing and reanalyzed rsl reconstructions from the same site developed using sediment cores indicates that compaction is unlikely to significantly distort rsl reconstructions produced from shallow 2 3 m thick sequences of salt marsh peat

a 20th century acceleration in global sea level rise 1 multi century sea level records and climate models indicate an acceleration of sea level rise but no 20th century acceleration has previously been detected a reconstruction of global sea level using tide gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea level rise but no significant acceleration over this period here we extend the reconstruction of global mean sea level back to 1870 and find a sea level rise from january 1870 to december 2004 of 195 mm a 20th century rate of sea level rise of 1 7 0 3 mm yr 1 and a significant acceleration of sea level rise of 0 013 0 006 mm yr 2 this acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed if this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm consistent with projections in the ipcc tar

application of stable carbon isotopes for reconstructing salt marsh floral zones and relative sea level new jersey usa we investigated use of 13c in bulk organic sediment to define the botanical origin of samples preserved in coastal sediment as a means to reconstruct relative sea level in new jersey usa modern transects at three sites demonstrated that low and high salt marsh floral zones dominated by c4 species spartina alterniflora and spartina patens were associated with sediment 13c values between 18 9 and 15 8 and occurred from mean tide level mtl to mean higher high water mhhw brackish transitional settings vegetated by phragmites australis with iva fructescens and typha sp c3 species and freshwater upland samples c3 species were characterized by bulk sediment 13c values of 27 0 to 22 0 and existed above mhhw parallel transects at one site suggested that intra site variability was not discernible the utility of 13c values for reconstructing relative sea level in new jersey is limited by an inability to differentiate between brackish sediments related to sea level and freshwater upland samples to facilitate this distinction in a 4 4 m core we used a multi proxy approach 13c values with presence or absence of agglutinated foraminifera to recognize indicative meanings for four sample types sediment with 13c values greater than 18 9 was derived from a vegetated salt marsh and formed between mtl and mhhw sediment with 13c values less than 22 0 and containing agglutinated foraminifera formed in a brackish transitional zone between mhhw and highest astronomical tide hat this is the narrowest elevational range of the four sample types and most precise sea level indicator sediment with 13c values less than 22 0 and lacking foraminifera can only constrain the upper bound of former sea level samples with intermediate values 22 0 to 18 9 formed between mtl and hat using these indicative meanings and radiocarbon dates we suggest that a transition from brackish to salt marsh 13c values recorded in the core took approximately 350 years from 1800 to 1450 cal a bp

upper mississippi pb as a mid 1800s chronostratigraphic marker in sediments from seasonally anoxic lakes in eastern canada abstract sediment cores from eight headwater lakes located in southern quebec eastern canada were analyzed for pb stable pb isotopes and the radioelements 210 pb 137 cs 241 am and 226 ra the depth profiles of stable pb isotope ratios show for the post 19th century period the influence of several isotopically distinct anthropogenic lead sources mainly including emissions from two canadian smelters and from leaded gasoline combustion in canada and in the united states a most interesting feature of the profiles however is the presence of sharp stable pb isotope ratio peaks near the depth horizon where excess 210 pb becomes undetectable using a binary mixing model and assuming that natural pb concentrations and isotopic compositions from the catchment are given by the pre industrial sediments at the bottom of the cores we find that a significant part of the anthropogenic pb supplied to the sediments at this horizon originated from smelting activities in the upper mississippi valley we assess that the pb isotope ratio peaks also observed in the laminated sediments of the pettaquamscutt estuary rhode island usa are an accurate chronostratigraphic marker for the validation of mid 19th century 210 pb derived dates given that the study lakes are located up to 2000 km from the mississippi valley we conclude that this isotopic pb signal provides a widely distributed time marker that is key to validate 210 pb chronologies in environmental archives from eastern north america

coastal wetland response to sea level rise in connecticut and new york abstract the persistence of salt marshes in the landscape depends on their ability to accommodate rising sea level and minimize additional flooding stress we use sediment cores and water level data from 14 marshes in connecticut and new york to evaluate how marsh accretion mineral and organic accumulation carbon storage and hydroperiod have changed from 1900 to 2012 we observe a regional acceleration in marsh accretion beginning around 1940 although marsh accretion did not reach parity with sea level rise for several additional decades despite a rise in marsh accretion from 1 0 mm yr 1 circa 1900 to 3 6 mm yr 1 at present the marsh surface has lost elevation relative to tidal datums declining relative elevations have led to increased tidal flooding particularly in high marsh settings as flooding increased organic matter accumulation accelerated at all marshes accelerating mineral deposition was only observed in areas of short form spartina alterniflora mineral and organic sediment accumulation co limit accretion but organic accumulation was the stronger limiting factor suggesting that marsh response to sea level rise in the region is sensitive to processes affecting rates of belowground production and decomposition marsh carbon storage over the period of study averaged 84 g c m 2 yr 1 increasing as accretion accelerated if marshes remain spatially intact as sea levels rise these results suggest that marshes have the capacity to become even greater c sinks

reconstructing holocene sea level using salt marsh foraminifera and transfer functions lessons from new jersey usa we present an expanded training set of salt marsh foraminifera for reconstructing holocene relative sea level change from 12 sites in new jersey that represent varied physiographic environments seven groups of foraminifera are recognized including four high or transitional marsh assemblages and a low salinity assemblage a weighted averaging transfer function trained on this dataset was applied to a dated core from barnegat bay to reconstruct sea level with uncertainties of 14 of tidal range we evaluate the transfer function using seven tests 1 leave one site out cross validation suggests that training sets of salt marsh foraminifera are robust to spatial autocorrelation caused by sampling along transects 2 segment wise analysis shows that the transfer function performs best at densely sampled elevations and overall estimates of model performance are over optimistic 3 dissimilarity and 4 non metric multi dimensional scaling evaluated the analogy between modern and core samples the closest modern analogues for core samples were drawn from six sites demonstrating the necessity of a multi site training set 5 goodness of fit statistics assessed the validity of reconstructions 6 the transfer function failed a test of significance because of the unusual properties of some cores selected for sea level reconstruction 7 agreement between reconstructed sea level and tide gauge measurements demonstrates the transfer function s utility copyright 2013 john wiley sons ltd

high resolution historical records from pettaquamscutt river basin sediments 2 pb isotopes reveal a potential new stratigraphic marker a high resolution record of pb deposition in rhode island over the past 250 yr was constructed using a sediment core from the anoxic pettaquamscutt river basin the sedimentary pb concentration record shows the well described maximum associated with leaded gasoline usage in the united states diminished pb variability during recorded periods of local industrial activity 1735 to 1847 supports the greater importance of regional atmospheric lead transport vs local inputs the pb isotopic composition at this site shows a clear maximum in anthropogenic 206 pb 207 pb in the mid 1800s similar peaks have also been observed in sediments from chesapeake bay and the great lakes suggesting a common source possible causes for this event include mining and smelting of pb ores in the upper mississippi valley district which accounted for almost all pb production in the united states in that period the timing of this event can provide an important stratigraphic marker for sediments deposited in the past 200 yr in the northeastern united states the downcore profile of anthropogenic 206 pb 207 pb provides a classic example of how changes in the mixture of ores for production of tetraethyl lead caused a regional scale shift in the sedimentary record and suggests that coal could have played a secondary role in pb emissions after 1920 copyright 2005 elsevier ltd

relative sea level trends in new york city during the past 1500 years new york city nyc is threatened by 21st century relative sea level rsl rise because it will experience a trend that exceeds the global mean and has high concentrations of low lying infrastructure and socioeconomic activity to provide a long term context for anticipated trends we reconstructed rsl change during the past 1500 years using a core of salt marsh sediment from pelham bay in the bronx foraminifera and bulk sediment 13c values were used as sea level indicators the history of sediment accumulation was established by radiocarbon dating and recognition of pollution and land use trends of known age in down core elemental isotopic and pollen profiles the reconstruction was generated within a bayesian hierarchical model to accommodate multiple proxies and to provide a unified statistical framework for quantifying uncertainty we show that rsl in nyc rose by 1 70 m since 575 ce including 0 38 m since 1850 ce the rate of rsl rise increased markedly at 1812 1913 ce from 1 0 to 2 5 mm y

glacial isostatic adjustment and the anomalous tide gauge record of eastern north america sea level variations as recorded by the global network of tide gauges represent a rich data set for studying a wide range of natural and anthropogenic phenomena such as the sea level rise induced by possible global warming for this purpose long term sea level trends must be corrected for the contaminating effects of continuing glacial isostatic adjustment1 5 gia the numerical correction procedure has for sites on the east coast of north america yielded a set of highly anomalous sea level rates characterized by systematic geographical trends2 4 5 we demonstrate that these trends are a consequence of inadequacies in the previous standard numerical prediction for gia in particular we find that the well known trends in the gia corrected tide gauge rates are eliminated if the lower mantle viscosity of the earth model used in the gia prediction is increased this result obviates the need to explain the anomalous trend as a manifestation of gulf stream ocean circulation4 or neotectonic processes2

gulf stream s induced sea level rise and variability along the u s mid atlantic coast 1 recent studies indicate that the rates of sea level rise slr along the u s mid atlantic coast have accelerated in recent decades possibly due to a slowdown of the atlantic meridional overturning circulation amoc and its upper branch the gulf stream gs we analyzed the gs elevation gradient obtained from altimeter data the florida current transport obtained from cable measurements the north atlantic oscillation nao index and coastal sea level obtained from 10 tide gauge stations in the chesapeake bay and the mid atlantic coast an empirical mode decomposition hilbert huang transformation emd hht method was used to separate long term trends from oscillating modes the coastal sea level variations were found to be strongly influenced by variations in the gs on timescales ranging from a few months to decades it appears that the gs has shifted from a 6 8 year oscillation cycle to a continuous weakening trend since about 2004 and that this trend may be responsible for recent acceleration in local slr the correlation between long term changes in the coastal sea level and changes in the gs strength was extremely high r 0 85 with more than 99 99 confidence that the correlation is not zero the impact of the gs on slr rates over the past decade seems to be larger in the southern portion of the mid atlantic bight near cape hatteras and is reduced northward along the coast the study suggests that regional coastal sea level rise projections due to climate change must take into account the impact of spatial changes in ocean dynamics

sea level change during the last 2500 years in new jersey usa relative sea level changes during the last w2500 years in new jersey usa were reconstructed to test if late holocene sea level was stable or included persistent and distinctive phases of variability foraminifera and bulk sediment d 13 c values were combined to reconstruct paleomarsh elevation with decimeter precision from sequences of salt marsh sediment at two sites using a multi proxy approach the additional paleoenvironmental information provided by bulk sediment d 13 c values reduced vertical uncertainty in the sea level reconstruction by about one third of that estimated from foraminifera alone using a transfer function the history of sediment deposition was constrained by a composite chronology an ageedepth model developed for each core enabled reconstruction of sea level with multi decadal resolution following correction for land level change 1 4 mm yr four successive and sustained multi centennial sea level trends were objectively identified and quantified 95 confidence interval using error in variables change point analysis to account for age and sea level uncertainties from at least 500 bc to 250 ad sea level fell at 0 11 mm yr the second period saw sea level rise at 0 62 mm yr from 250 ad to 733 ad between 733 ad and 1850 ad sea level fell at 0 12 mm yr the reconstructed rate of sea level rise since w1850 ad was 3 1 mm yr and represents the most rapid period of change for at least 2500 years this trend began between 1830 ad and 1873 ad since this change point reconstructed sea level rise is in agreement with regional tide gauge records and exceeds the global average estimate for the 20th century these positive and negative departures from background rates demonstrate that the late holocene sea level was not stable in new jersey

spatial variability of late holocene and 20th century sea level rise along the atlantic coast of the united states accurate estimates of global sea level rise in the pre satellite era provide a context for 21 st century sea level predictions but the use of tide gauge records is complicated by the contributions from changes in land level due to glacial isostatic adjustment gia we have constructed a rigorous quality controlled database of late holocene sea level indices from the u s atlantic coast exhibiting subsidence rates of 0 8 mm a 1 in maine increasing to rates of 1 7 mm a 1 in delaware and a return to rates 0 9 mm a 1 in the carolinas this pattern can be attributed to ongoing gia due to the demise of the laurentide ice sheet our data allow us to defi ne the geometry of the associated collapsing proglacial forebulge with a level of resolution unmatched by any other currently available method the corresponding rates of relative sea level rise serve as background rates on which future sea level rise must be superimposed we further employ the geological data to remove the gia component from tide gauge records to estimate a mean 20 th century sea level rise rate for the u s atlantic coast of 1 8 0 2 mm a 1 similar to the global average however we fia distinct spatial trend in the rate of 20 th century sea level rise increasing from maine to south carolina this is the fi rst evidence of this phenomenon from observational data alone we suggest this may be related to the melting of the greenland ice sheet and or ocean steric effects

oceanic control of sea level rise patterns along the east coast of the united states 1 along the eastern seaboard of the u s from florida to maine sea level rise slr shows notable patterns and significant deviation from the global mean which have been attributed to land subsidence consistent with several recent studies we analyze various observation and modeling data and find that ocean dynamics is also an important factor in explaining these coastal slr patterns despite a southward shift since the 1990s an overall northward shift of the gulf stream during the twentieth century contributed to the faster slr in the mid atlantic region north carolina to new jersey in response to the 21st century climatic forcing the rise fall of the dynamic sea level north south of cape hatteras is mainly induced by the significant decline of ocean density contrast across the gulf stream this baroclinic process is the likely cause of the recent switch of the coastal slr to a pattern with faster slower rates north south of cape hatteras citation yin j and p b goddard 2013 oceanic control of sea level rise patterns along the east coast of the united states geophys res lett 40 doi 10 1002 2013gl057992

isotopic record of lead pollution in lake sediments from the northeastern united states abstract although it is common knowledge that pb concentrations have increased in lake sediments in the northeastern united states over the last 150 years the processes responsible have been the subject of debate in this study differences in lead isotopic compositions and concentrations in sediment from large lakes lake erie ontario and michigan and small ones deep lake and lake andrus are used to infer temporal changes in the source s of anthropogenic pb in the great lakes region a natural background component of pb is present in sediment deposited prior to 1860 in lake erie and the other lakes as indicated from low pb concentrations and uniform lead isotopic compositions changes in isotopic ratios of lake sediment reflect differing sources of anthropogenic pb superimposed on the natural component such as regional deforestation from 1860 1890 followed by coal combustion and ore smelting through 1930 combustion of leaded gasoline was the dominant anthropogenic pb source to the atmosphere and by inference to lake sediment from 1930 1980 temporal changes in lead isotopic compositions in lake sediment suggest that the source of the pb used in gasoline additives gradually changed from 1930 to present the best example is a distinct shift in lead isotopic ratios in lake sediment deposited after 1970 which corresponds to increased pb production from the viburnum trend deposits in missouri present in all lakes except ontario however the changes in lead isotopic compositions are much less variable than and do not parallel those calculated on the basis of annual united states mine production and imports rather anthropogenic recycling of pb as well as natural mixing processes during emission transport and deposition of pb in lake sediment control most of the variation in lead isotope ratios differences in lead isotopic ratios in lake michigan erie and deep lake sediment preserve regional differences in lead isotopic ratios from u s and canadian sources first noted in aerosols by sturges and barrie 1987 more localized sources of pb such as point discharges are needed to explain the results from lake ontario and andrus

holocene sea level database for the atlantic coast of the united states we have constructed a database of holocene relative sea level rsl observations for the atlantic coast of the united states the database contains 492 index points which locate the position of rsl in time and space and 344 limiting dates which constrain the minimum or maximum limit of former sea level the majority of the index points in the database are from 6 ka bp to present with only 7 older than 6 ka bp spatially index points are distributed between maine and south carolina but there is an absence of data from georgia and the atlantic coast of florida the database is sub divided into 16 regions based on the distance from the former laurentide ice sheet and are classified depending upon their susceptibility to compaction the index points and limiting data demonstrate that rsl did not exceed present 0 m during the holocene except potentially in regions 1 and 2 eastern maine and southern maine rates of rsl change were highest during the early holocene and have decreased over time due to the diminishing response of the earth s mantle to glacial isostatic adjustment and reduction of ice equivalent meltwater input along the atlantic coast of the united states the linear rate of rsl rise prior to 4 ka bp ranged from 0 5 to 4 5 mm a 1 compared to 0 6 1 8 mm a 1 from 4 ka bp to ad 1900 the database suggests minimal 0 3 mm yr changes in these rates of rsl rise during the late holocene deglaciation of the laurentide ice sheet caused the spatial variability captured by the database the maximum rate of late holocene and ongoing rsl rise occurred in mid atlantic regions new jersey and inner delaware because of collapse of the peripheral forebulge

global glacial isostasy and the surface of the ice age earth the ice 5g vm2 model and grace abstract the 100 kyr quasiperiodic variation of continental ice cover which has been a persistent feature of climate system evolution throughout the most recent 900 kyr of earth history has occurred as a consequence of changes in the seasonal insolation regime forced by the influence of gravitational n body effects in the solar system on the geometry of earth s orbit around the sun the impacts of the changing surface ice load upon both earth s shape and gravitational field as well as upon sea level history have come to be measurable using a variety of geological and geophysical techniques these observations are invertible to obtain useful information on both the internal viscoelastic structure of the solid earth and on the detailed spatiotemporal characteristics of glaciation history this review focuses upon the most recent advances that have been achieved in each of these areas advances that have proven to be central to the construction of the refined model of the global process of glacial isos

flandrian sea level changes in the fenland ii tendencies of sea level movement altitudinal changes and local and regional factors stratigraphic micropalaeontologic and radiocarbon data show that since c 6500 bp the fenland has been influenced by 7 periods of positive sea level tendencies and by 6 periods of negative sea level tendencies despite the numerous problems associated with the reconstruction of past altitudes of sea level the periods of positive sea level tendencies were clearly characterised by a rise in sea level the development of transgressive overlaps and a landward movement of the coastline the periods of negative sea level tendencies were characterised by the development of regressive overlaps a seaward movement of the coastline and a reduced or negative rate of sea level rise the various altitudinal errors do not permit the incontrovertible distinction of periods of falling sea levels all changes within the fenland were not synchronous and local factors influenced the exact nature of each sea level indicator dominant regional and local factors have been identified for different areas and different time periods the chronological and spatial characteristics of the sequences within the fenland are best explained by a palaeocoastline without supratidal barriers controlling sedimentation the data indicate an average crustal subsidence in the fenland of 0 9m 1000 years since c 6500 bp and the pattern of positive and negative tendencies of sea level movement is also seen in the chronologies for north west england and north east scotland

using foraminiferal transfer functions to produce high resolution sea level records from salt marsh deposits maine usa quantitative analyses of foraminiferal distributions along the coast of maine are used to provide transfer functions for reconstruction of sea level changes from fossil foraminiferal assemblages the indicative meaning of fossil assemblages is most accurately predicted by a training set that incorporates live and dead foraminifera and that uses flooding duration not height as the predictor variable sea level records are produced for two sites in maine usa a middle marsh site in scarboro and a high marsh site in machiasport these records offer temporal resolution of five to seven years and span the past century they are compared with instrumental data from a nearby tidal station to assess their accuracy strong correlations are found between the geologic records and the observational data in particular between the foraminiferal record from machiasport and the tide gauge record from eastport r2 0 83 p 0 005 thus a foraminifera based transfer function approach offers great potential for reso