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  • Scholz, Denis  (50)
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  • 1
    Language: English
    In: Earth and Planetary Science Letters, May 15, 2012, Vol.331-332, p.187(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.epsl.2012.03.019 Byline: Cyril Giry, Thomas Felis, Martin Kolling, Denis Scholz, Wei Wei, Gerrit Lohmann, Sander Scheffers Keywords: coral Sr/Ca; southern Caribbean climate; sea surface temperature; seasonality; interannual to multidecadal variability; ENSO teleconnection Abstract: Proxy reconstructions of tropical Atlantic sea surface temperature (SST) that extend beyond the period of instrumental observations have primarily focused on centennial to millennial variability rather than on seasonal to multidecadal variability. Here we present monthly-resolved records of Sr/Ca (a proxy of SST) from fossil annually-banded Diploria strigosa corals from Bonaire (southern Caribbean Sea). The individual corals provide time-windows of up to 68years length, and the total number of 295years of record allows for assessing the natural range of seasonal to multidecadal SST variability in the western tropical Atlantic during snapshots of the mid- to late Holocene. Comparable to modern climate, the coral Sr/Ca records reveal that mid- to late Holocene SST was characterised by clear seasonal cycles, persistent quasi-biennial and prominent interannual as well as inter- to multidecadal-scale variability. However, the magnitude of SST variations on these timescales has varied over the last 6.2ka. The coral records show increased seasonality during the mid-Holocene consistent with climate model simulations indicating that southern Caribbean SST seasonality is induced by insolation changes on orbital timescales, whereas internal dynamics of the climate system play an important role on shorter timescales. Interannual SST variability is linked to ocean-atmosphere interactions of Atlantic and Pacific origin. Pronounced interannual variability in the western tropical Atlantic is indicated by a 2.35ka coral, possibly related to a strengthening of the variability of the El Nino/Southern Oscillation throughout the Holocene. Prominent inter- to multidecadal SST variability is evident in the coral records and slightly more pronounced in the mid-Holocene. We finally argue that our coral data provide a target for studying Holocene climate variability on seasonal and interannual to multidecadal timescales, when using further numerical models and high-resolution proxy data. Article History: Received 13 May 2011; Revised 20 December 2011; Accepted 13 March 2012 Article Note: (miscellaneous) Editor: P. DeMenocal
    Keywords: El Nino -- Analysis ; Southern Oscillation -- Analysis ; Corals -- Analysis ; Holocene Paleogeography -- Analysis
    ISSN: 0012-821X
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Earth and Planetary Science Letters, 15 May 2012, Vol.331-332, pp.187-200
    Description: Proxy reconstructions of tropical Atlantic sea surface temperature (SST) that extend beyond the period of instrumental observations have primarily focused on centennial to millennial variability rather than on seasonal to multidecadal variability. Here we present monthly-resolved records of Sr/Ca (a proxy of SST) from fossil annually-banded corals from Bonaire (southern Caribbean Sea). The individual corals provide time-windows of up to 68 years length, and the total number of 295 years of record allows for assessing the natural range of seasonal to multidecadal SST variability in the western tropical Atlantic during snapshots of the mid- to late Holocene. Comparable to modern climate, the coral Sr/Ca records reveal that mid- to late Holocene SST was characterised by clear seasonal cycles, persistent quasi-biennial and prominent interannual as well as inter- to multidecadal-scale variability. However, the magnitude of SST variations on these timescales has varied over the last 6.2 ka. The coral records show increased seasonality during the mid-Holocene consistent with climate model simulations indicating that southern Caribbean SST seasonality is induced by insolation changes on orbital timescales, whereas internal dynamics of the climate system play an important role on shorter timescales. Interannual SST variability is linked to ocean–atmosphere interactions of Atlantic and Pacific origin. Pronounced interannual variability in the western tropical Atlantic is indicated by a 2.35 ka coral, possibly related to a strengthening of the variability of the El Niño/Southern Oscillation throughout the Holocene. Prominent inter- to multidecadal SST variability is evident in the coral records and slightly more pronounced in the mid-Holocene. We finally argue that our coral data provide a target for studying Holocene climate variability on seasonal and interannual to multidecadal timescales, when using further numerical models and high-resolution proxy data. ► Monthly coral Sr/Ca records of tropical Atlantic SST for snapshots of the Holocene. ► ~ 295 yr from decade-long well-distributed time-windows over the last 6.2 ka. ► Proxy-model comparison: orbital control on tropical & North Atlantic SST seasonality. ► Increasing ENSO influence on tropical Atlantic SST variability across the Holocene. ► Inter- to multidecadal SST variability at 6.2 ka in AMO-sensitive region.
    Keywords: Coral Sr/Ca ; Southern Caribbean Climate ; Sea Surface Temperature ; Seasonality ; Interannual to Multidecadal Variability ; Enso Teleconnection ; Geology ; Physics
    ISSN: 0012-821X
    E-ISSN: 1385-013X
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  • 3
    Language: English
    In: Journal of Human Evolution, January 2016, Vol.90, pp.183-197
    Description: Cueva Victoria has provided remains of more than 90 species of fossil vertebrates, including a hominin phalanx, and the only specimens of the African cercopithecid in Europe. To constrain the age of the vertebrate remains we used paleomagnetism, vertebrate biostratigraphy and Th/U dating. Normal polarity was identified in the non-fossiliferous lowest and highest stratigraphic units (red clay and capping flowstones) while reverse polarity was found in the intermediate stratigraphic unit (fossiliferous breccia). A lower polarity change occurred during the deposition of the decalcification clay, when the cave was closed and karstification was active. A second polarity change occurred during the capping flowstone formation, when the upper galleries were filled with breccia. The mammal association indicates a post-Jaramillo age, which allows us to correlate this upper reversal with the Brunhes–Matuyama boundary (0.78 Ma). Consequently, the lower reversal (N-R) is interpreted as the end of the Jaramillo magnetochron (0.99 Ma). These ages bracket the age of the fossiliferous breccia between 0.99 and 0.78 Ma, suggesting that the capping flowstone was formed during the wet Marine Isotopic Stage 19, which includes the Brunhes–Matuyama boundary. Fossil remains of have been only found ∼1 m below the B/M boundary, which allows us to place the arrival of to Cueva Victoria at ∼0.9–0.85 Ma. The fauna of Cueva Victoria lived during a period of important climatic change, known as the Early-Middle Pleistocene Climatic Transition. The occurrence of the oldest European Acheulean tools at the contemporaneous nearby site of Cueva Negra suggest an African dispersal into SE Iberia through the Strait of Gibraltar during MIS 22, when sea-level was ∼100 m below its present position, allowing the passage into Europe of, at least, and bearing Acheulean technology.
    Keywords: Magnetostratigraphy ; 230th/U Dating ; Theropithecus ; Early Humans ; Mis 22 ; Afro-Iberian Dispersal ; Anthropology ; Biology
    ISSN: 0047-2484
    E-ISSN: 1095-8606
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  • 4
    Language: English
    In: International Journal of Speleology, 01 May 2018, Vol.47(2), pp.145-154
    Description: The investigation of the internal structure of calcite crystals is a new focus in speleothem science, especially in the range of crystallization temperatures close to 0°C. Recently found calcite spars from Zinnbergschacht Cave of the Franconian Alb (SE Germany) are ideal for multi-method investigation. The elongated calcites (up to 6 cm in length) with three to six lateral faces and basal triangular faces at the ends are observed in collapse-zones in the cave. 230Th/U-ages of 38.9 ka suggest formation during the periglacial Weichselian, between the Scandinavian and Alpine Glaciations. The δ18O and δ13C values of the calcite spars vary from -11.18 to -16.11‰ V-PDB and from -4.78 to -6.13‰ V-PDB, respectively. The exceptionally low δ18O values of these calcites appear to be due to precipitation in pools on ice. The values deviate considerably from those of conventional interglacial speleothems (δ18O = -7.21 to -7.55‰, δ13C = -9.77 to -10.86‰) and also from true Weichselian cryogenic calcites (composite spherulites and rhombohedral chains with δ18O = -15.06 to -18.04‰ and with δ13C = -3.52 to -4.13‰). The δ18O values of the latter calcites is typical of cryogenesis of calcites with extensive oxygen isotope fractionation (preferred incorporation of 18O into the co-occurring ice). Thus, the δ18O values of the calcites suggest cold conditions up to the beginning of cryogenesis. Cathodoluminescence (CL) and backscattered electrons (BSE) indicate the distribution of impurities within the calcite spars as pigmented triangles surrounded by clear calcite, with a higher density of the triangles in the outer areas. Three hierarchies of triangles can be distinguished by BSE, documenting a filigreed primary structure of the spars. Electron backscatter diffraction (EBSD) reveals a divergent orientation of the triangular subcrystals from the center to the outer corners of the calcites. Thus, their internal structure reflects an example of fascicular optic fibrous calcites (FOFC), frequently discussed in carbonate petrology.
    Keywords: Weichselian ; Cryogenic Calcites ; Fascicular Optic Fibrous Calcite ; Electron Backscatter Diffraction ; Franconian Alb ; Geography
    ISSN: 0392-6672
    E-ISSN: 1827-806X
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  • 5
    In: Paleoceanography and Paleoclimatology, February 2018, Vol.33(2), pp.198-213
    Description: The seasonality of hydroclimate during past periods of warmer than modern global temperatures is a critical component for understanding future climate change scenarios. Although only partially analogous to these scenarios, the last interglacial (LIG, Marine Isotope Stage 5e, ~127–117 ka) is a popular test bed. We present coral δO monthly resolved records from multiple Bonaire (southern Caribbean) fossil corals () that date to between 130 and 118 ka. These records represent up to 37 years and cover a total of 105 years, offering insights into the seasonality and characteristics of LIG tropical Atlantic hydroclimate. Our coral δO records and available coral Sr/Ca‐sea surface temperature (SST) records reveal new insights into the variable relationship between the seasonality of tropical Atlantic seawater δO (δO) and SST. Coral δO seasonality is found to covary with SST and insolation seasonality throughout the LIG, culminating in significantly higher than modern values at 124 and 126 ka. At 124 ka, we reconstruct a 2 month lead of the coral δO versus the Sr/Ca‐SST annual cycle and increased δO seasonality. A fully coupled climate model simulates a concomitant increase of southern Caribbean Sea summer precipitation and depletion of summer δO. LIG hydroclimate at Bonaire differed from today's semiarid climate with a minor rainy season during winter. Cumulatively, our coral δO, δO, and model findings indicate a mid‐LIG northward expansion of the South American Intertropical Convergence Zone into the southern Caribbean Sea, highlighting the importance of regional aspects within model and proxy reconstructions of LIG hydroclimate seasonality. Last interglacial (LIG) coral δ18O records are used to reconstruct tropical Atlantic seawater δ18O (δ18Oseawater) seasonality A 37 year mid‐ last interglacial coral detects higher than modern δ18Oseawater seasonality and a 2 month lead of coral δ18O versus Sr/Ca Mid‐ last interglacial climate model and coral findings indicate an Intertropical Convergence Zone expansion into the South Caribbean Sea
    Keywords: Last Interglacial ; Tropical Atlantic Climate ; Hydroclimate Seasonality ; Coral Seawater Δ 18 O Seasonality ; Intertropical Convergence Zone
    ISSN: 2572-4517
    ISSN: 19449186
    E-ISSN: 2572-4525
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  • 6
    Language: English
    In: Sci Rep, 2017, Vol.7(1), pp.15825-15825
    Description: Explanations of the Classic Maya civilization demise on the Yucatán Peninsula during the Terminal Classic Period (TCP; ~CE 750–1050) are controversial. Multiyear droughts are one likely cause, but the role of the Caribbean Sea, the dominant moisture source for Mesoamerica, remains largely unknown. Here we present bimonthly-resolved snapshots of reconstructed sea surface temperature (SST) and salinity (SSS) variability in the southern Caribbean from precisely dated fossil corals. The results indicate pronounced interannual to decadal SST and SSS variability during the TCP, which may be temporally coherent to precipitation anomalies on the Yucatán. Our results are best explained by changed Caribbean SST gradients affecting the Caribbean low-level atmospheric jet with consequences for Mesoamerican precipitation, which are possibly linked to changes in Atlantic Meridional Overturning Circulation strength. Our findings provide a new perspective on the anomalous hydrological changes during the TCP that complement the oft-suggested southward displacement of the Intertropical Convergence Zone. We advocate for a strong role of Caribbean SST and SSS condition changes and related ocean-atmosphere interactions that notably influenced the propagation and transport of precipitation to the Yucatán Peninsula during the TCP.
    Keywords: Biology;
    ISSN: 2045-2322
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  • 7
    In: Nature Communications, 2015, Vol.6
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.gloplacha.2009.10.006 Byline: Thomas Felis (a), Norel Rimbu (b)(c) Keywords: Mediterranean; Middle East; Red Sea; palaeoclimate; North Atlantic Oscillation; corals; oxygen isotopes Abstract: Annually banded reef corals from the northern Red Sea provide a high-resolution archive of past climate variations at the southeastern rim of the Mediterranean basin. Subseasonally resolved oxygen isotope records derived from the carbonate skeletons of these massive colonies robustly document seasonality and interannual to decadal climate variability. These proxy records of climate, supported by analyses of instrumental data and model simulations, reveal the prominent role of the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) in controlling eastern Mediterranean/Middle East climate on seasonal, interannual to decadal and orbital timescales, most pronounced during winter. Variability at interannual periods of 5-6yr evident in the coral records is indicative of AO/NAO-like atmospheric variability over the Northern Hemisphere and its influence on eastern Mediterranean/Middle East climate during the last centuries, the late Holocene and the last interglacial period. The coral oxygen isotope records, which are recording temperature and surface evaporation in the northern Red Sea, are linked via AO/NAO-controlled atmospheric circulation changes to variations in temperature and precipitation throughout the Mediterranean and Middle East region. Whereas the entire eastern Mediterranean/Middle East region experiences colder winters during the high-index state of the AO/NAO, the resulting changes in hydrologic balance have a more complex spatial pattern. More arid conditions in the northern Red Sea are accompanied by drier winters in the northeastern Mediterranean but by wetter winters along the southeastern rim of the Mediterranean Sea. This observation may raise difficulties for proxy-based reconstructions of eastern Mediterranean precipitation from the Levant, which is located in the transition zone between positive and negative precipitation anomalies. Compared to the AO/NAO, the atmospheric teleconnections of the El NiA[+ or -]o-Southern Oscillation (ENSO) on eastern Mediterranean/Middle East climate, which are modulated by higher-latitude atmospheric circulation over the North Pacific-North Atlantic region, are weaker and non-stationary. Author Affiliation: (a) MARUM -- Center for Marine Environmental Sciences, University of Bremen, GEO Building, Klagenfurter Str., 28359 Bremen, Germany (b) Department of Atmospheric Physics, Faculty of Physics, University of Bucharest, Bucharest, Romania (c) Climed Norad, Zeicani 25, Bucharest, Romania Article History: Received 19 January 2009; Accepted 19 October 2009
    Keywords: Rain – Analysis ; Precipitation Variability – Analysis ; Atmospheric Physics – Analysis ; Climate – Analysis ; Atmospheric Circulation – Analysis ; Interglacial Periods – Analysis ; El Nino – Analysis ; Carbonates – Analysis ; Natural Cycles – Analysis;
    ISSN: 2041-1723
    ISSN: 09218181
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  • 8
    Language: English
    In: Earth and Planetary Science Letters, 01 September 2016, Vol.449, pp.418-429
    Description: Reconstructions of last interglacial (LIG, MIS 5e, ∼127–117 ka) climate offer insights into the natural response and variability of the climate system during a period partially analogous to future climate change scenarios. We present well preserved fossil corals ( ) recovered from the southern Caribbean island of Bonaire (Caribbean Netherlands). These have been precisely dated by the Th/U-method to between 130 and 120 ka ago. Annual banding of the coral skeleton enabled construction of time windows of monthly resolved strontium/calcium (Sr/Ca) temperature proxy records. In conjunction with a previously published 118 ka coral record, our eight records of up to 37 years in length, cover a total of 105 years within the LIG period. From these, sea surface temperature (SST) seasonality and variability in the tropical North Atlantic Ocean is reconstructed. We detect similar to modern SST seasonality of ∼2.9 °C during the early (130 ka) and the late LIG (120–118 ka). However, within the mid-LIG, a significantly higher than modern SST seasonality of 4.9 °C (at 126 ka) and 4.1 °C (at 124 ka) is observed. These findings are supported by climate model simulations and are consistent with the evolving amplitude of orbitally induced changes in seasonality of insolation throughout the LIG, irrespective of wider climatic instabilities that characterised this period. The climate model simulations suggest that the SST seasonality changes documented in our LIG coral Sr/Ca records are representative of larger regions within the tropical North Atlantic. These simulations also suggest that the reconstructed SST seasonality increase during the mid-LIG is caused primarily by summer warming. A 124 ka old coral documents, for the first time, evidence of decadal SST variability in the tropical North Atlantic during the LIG, akin to that observed in modern instrumental records.
    Keywords: Coral Sr/Ca ; the Last Interglacial ; Caribbean Climate ; Sea Surface Temperature ; Seasonality ; Quasi-Biennial to Decadal Variability ; Geology ; Physics
    ISSN: 0012-821X
    E-ISSN: 1385-013X
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  • 9
    Language: English
    Keywords: Internal Coral Chronology ; Diploria Strigosa, D18o ; Delta 18o, Seawater, Reconstructed ; Calculated, Monthly Interpolated ; Mass Spectrometer Finnigan Mat 251 ; Calculated, See Reference(S) ; Integrierte Analyse Zwischeneiszeitlicher Klimadynamik (Interdynamik) ; Center For Marine Environmental Sciences (Marum)
    Source: DataCite
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  • 10
    Language: English
    Keywords: Internal Coral Chronology ; Diploria Strigosa, D18o ; Delta 18o, Seawater, Reconstructed ; Calculated, Monthly Interpolated ; Mass Spectrometer Finnigan Mat 251 ; Calculated, See Reference(S) ; Integrierte Analyse Zwischeneiszeitlicher Klimadynamik (Interdynamik) ; Center For Marine Environmental Sciences (Marum)
    Source: DataCite
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