1,721,177 research outputs found
Past and future sea-level rise along the coast of North Carolina, USA
No full textWe evaluate relative sea level (RSL) trajectories for North Carolina, USA, in the context of tide-gauge measurements and geological sea-level proxy reconstructions spanning the last ∼11,000 years. RSL rise was fastest (∼7 mm/yr) during the early Holocene and slowed over time with the end of the deglaciation. During the pre-Industrial Common Era (i.e., 0–1800 CE), RSL rise (∼0.7 to 1.1 mm/yr) was driven primarily by glacio-isostatic adjustment, though dampened by tectonic uplift along the Cape Fear Arch. Ocean/atmosphere dynamics caused centennial variability of up to ∼0.6 mm/yr around the long-term rate. It is extremely likely (probability P = 0.95) that 20th century RSL rise at Sand Point, NC, (2.8 ± 0.5 mm/yr) was faster than during any other century in at least 2,900 years. Projections based on a fusion of process models, statistical models, expert elicitation, and expert assessment indicate that RSL at Wilmington, NC, is very likely (P = 0.90) to rise by 42–132 cm between 2000 and 2100 under the high-emissions RCP 8.5 pathway. Under all emission pathways, 21st century RSL rise is very likely (P > 0.90) to be faster than during the 20th century. Due to RSL rise, under RCP 8.5, the current ‘1-in-100 year’ flood is expected at Wilmington in ∼30 of the 50 years between 2050-2100.The final publication is available at Springer via http://dx.doi.org/10.1007/s10584-015-1451-xPeer reviewe
Sea-Level change and subsidence in the Delaware Estuary during the last ~2200 years
No full textWe produced eight new sea-level index points that reconstruct a ~2.5 m relative sea-level (RSL) rise at Sea Breeze in the Delaware Bay from ~200 BCE to 1800 CE. The precision of our reconstruction improved upon existing data by using high-resolution surveying methods, AMS radiocarbon dating of in-situ plant macrofossils collected immediately above the basal contact between pre-Holocene sand and salt-marsh sediments, foraminifera as sea-level indicators, and by accounting for tidal range changes through time. Our new data were combined with a database of 65 sea-level index points available for the Delaware Bay to estimate the rate of RSL rise in the upper (1.26 ± 0.33 mm/yr) and lower bay (1.30 ± 0.36 mm/yr) using a spatial-temporal model. Correction for changes in tidal range through time removed the disparity in rate between the upper and lower Delaware Bay that had previously been postulated. After paleotidal correction, the rates of RSL rise estimated for the Delaware Bay (1.25 ± 0.27 mm/yr) correlate with the ~1.3 mm/yr rate reported for New Jersey, Maryland, and Virginia, and confirm that the maximal ongoing forebulge collapse along the U.S. Atlantic coast is focused on the mid-Atlantic.Peer reviewe
Holocene Relative Sea-Level Changes from Near-, Intermediate-, and Far-Field Locations
No full textHolocene relative sea-level (RSL) records exhibit spatial and temporal variability that arises mainly from the interaction of eustatic (land ice volume and thermal expansion) and isostatic (glacio- and hydro-) factors. We fit RSL histories from near-, intermediate-, and far-field locations with noisy-input Gaussian process models to assess rates of RSL change. Records from near-field regions (e.g., Antarctica, Greenland, Canada, Sweden, and Scotland) reveal a complex pattern of RSL fall from a maximum marine limit due to the net effect of eustatic sea-level rise and glacio-isostatic uplift with rates of RSL fall as great as -69 ± 9 m/ka. Intermediate-field regions (e.g., mid-Atlantic and Pacific coasts of the United States, Netherlands, Southern France, St. Croix) display variable rates of RSL rise from the cumulative effect of isostatic and eustatic factors. Fast rates of RSL rise (up to 10 ± 1 m/ka) are found in the early Holocene in regions near the center of forebulge collapse. Far-field RSL records exhibit a mid-Holocene highstand, the timing (between 8 and 4 ka) and magnitude (between <1 and 6 m) of which varies among South America, Africa, Asia and Oceania regions.Peer reviewe
Temperature-driven global sea-level variability in the Common Era
No full textWe assess the relationship between temperature and global sea-level (GSL) variability over the Common Era through a statistical metaanalysis of proxy relative sea-level reconstructions and tide-gauge data. GSL rose at 0.1 ± 0.1 mm/y (2σ) over 0–700 CE. A GSL fall of 0.2 ± 0.2 mm/y over 1000–1400 CE is associated with ∼0.2 °C global mean cooling. A significant GSL acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability P≥0.95) faster than during any of the previous 27 centuries. A semiempirical model calibrated against the GSL reconstruction indicates that, in the absence of anthropogenic climate change, it is extremely likely (P=0.95) that 20th century GSL would have risen by less than 51% of the observed 13.8±1.5 cm. The new semiempirical model largely reconciles previous differences between semiempirical 21st century GSL projections and the process model-based projections summarized in the Intergovernmental Panel on Climate Change’s Fifth Assessment Report.This article is available Open Access at the Link to published version: http://dx.doi.org/10.1016/j.emospa.2016.02.006Also available as related resources: Supporting Information (PDF), Dataset S1 (PDF), Dataset S2 (Excel), Dataset S3 (Excel).Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Can we detect centennial sea-level variations over the last three thousand years in Israeli archaeological records?
Get PDFArchaeological remains are valuable relative sea-level (RSL) indicators in Israel, a tectonically stable coast with minor isostatic inputs. Previous research has used archaeological indicators to argue for centennial sea-level fluctuations. Here, we place archaeological indicators in a quality-controlled dataset where all indicators have consistently calculated vertical and chronological uncertainties, and we subject the data to statistical analysis. We combine the archaeological data with bio-construction data from Dendropoma petraeum colonial vermetids. The final dataset consists of 99 relative sea-level index points and 12 limiting points from the last 4000 a. The temporal distribution of the index points is uneven; Israel has only four index points before 2000 a BP. We apply an Errors-In-Variables Integrated Gaussian Process (EIV IGP) to the index points to model the evolution of RSL. Results show RSL in Israel rose from −0.8 ± 0.5 m at ∼2750 a BP (Iron Age) to 0.0 ± 0.1 m by ∼1850 a BP (Roman period) at 0.8 mm/a, and continued rising to 0.1 ± 0.1 m until ∼1600 a BP (Byzantine Period). RSL then fell to −0.3 ± 0.1 m by 0.5 mm/a until ∼650 a BP (Late Arab period), before returning to present levels at a rate of 0.4 mm/a. The re-assessed Israeli record supports centennial-scale RSL fluctuations during the last 3000 a BP, although the magnitude of the RSL fall during the last 2000 a BP is 50% less. The new Israel RSL record demonstrates correspondence with regional climate proxies. This quality-controlled Israeli RSL dataset can serve as a reference for comparisons with other sea-level records from the Eastern Mediterranean
Stable carbon isotope and C/N geochemistry of coastal wetland sediments as a sea-level indicator
No full textStable carbon isotopes (δ13C) and the ratio of organic carbon to total nitrogen (C/N) are able to differentiate sources of organic matter that accumulate in coastal depositional sequences, which makes them useful to reconstruct former sea levels. This chapter describes the factors that influence δ13C and C/N geochemistry of coastal wetland sediments, outlines basic methods for its use in relative sea-level reconstruction, and draws attention to several case studies
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