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Elsa Cortijo - One of the best experts on this subject based on the ideXlab platform.

  • Constraints on the duration and freshwater release of Heinrich Event 4 through isotope modelling
    Nature, 2004
    Co-Authors: D. Roche, Delphine Paillard, Elsa Cortijo
    Abstract:

    Heinrich Events--abrupt climate cooling Events due to ice-sheet instability that occurred during the last glacial period--are recorded in sediment cores throughout the North Atlantic Ocean. Modelling studies have described likely physical mechanisms for these Events, but the quantitative characteristics of Heinrich Events are less well known. Here we use a climate model of intermediate complexity that explicitly calculates the distribution of oxygen isotopes in the oceans to simulate Heinrich Event 4 at about 40,000 yr ago. We compare an ensemble of scenarios for this Heinrich Event with oxygen isotope data measured in foraminiferal calcite of a comprehensive set of sediment cores. From this comparison, we obtain a duration of 250 +/- 150 yr and an ice release of 2 +/- 1 m sea-level equivalent for Heinrich Event 4, significantly reducing the uncertainties in both values compared to earlier estimates of up to 2,000 yr and 15 m of sea-level equivalent ice release, respectively. Our results indicate that the consequences of Heinrich Events may have been less severe than previously assumed, at least with respect to Greenland climate and sea level.

  • A simulation of the Atlantic meridional circulation during Heinrich Event 4 using reconstructed sea surface temperatures and salinities
    Paleoceanography, 1999
    Co-Authors: Delphine Paillard, Elsa Cortijo
    Abstract:

    With a simplified two-dimensionnal Atlantic Ocean model, we investigate the response of the deep ocean circulation to reconstructed sea surface salinity and temperature used as surface boundary conditions at two time slices: just before and during Heinrich Event 4. In contrast to previous studies, we do not make any assumption about freshwater input. Our model results suggest that the recorded estimations of surface hydrological changes during an Heinrich Event are able to induce a drastic slowdown, or even a collapse, of the overall Atlantic thermohaline circulation. This is, to some extent, consistent with records of the deep sea ventilation at these times.

  • Evidence for changes in the North Atlantic Deep Water linked to meltwater surges during the Heinrich Events
    Earth and Planetary Science Letters, 1997
    Co-Authors: Laurence Vidal, Elsa Cortijo, E. Michel, Jean-claude Duplessy, Laurent Labeyrie, Maurice Arnold, S. Becqué, T.c.e. Van Weering
    Abstract:

    Abstract Deep sea sediment records from North Atlantic cores (40°N–55°N) provide evidence of several massive iceberg discharges, known as Heinrich Events, during the last glacial period. High resolution benthic δ 18 O and δ 13 C records from North Atlantic sediment cores were used to monitor the impact of Heinrich Events on thermohaline circulation and to estimate the sensitivity of deep oceanic circulation to changes in freshwater input to the North Atlantic surface waters. Our data indicate that major rearrangements of deep-water masses were directly associated with these massive iceberg discharges. To trace in detail the deep water conditions in the North Atlantic, benthic δ 13 C values in several cores were used to generate time slices before, during and after Heinrich Event 4 dated at ∼ 35 ka BP. Although North Atlantic Deep Water continued to form during the oxygen isotope stage 3 at 37 ka BP, deep circulation was characterized by an increased incursion of deep waters of southern origin, which reduced the δ 13 C composition of North Atlantic deep waters, particularly in the eastern Atlantic basin. North Atlantic Deep Water production was reduced during Heinrich Layer 4 (HL4 at ∼ 35 ka BP) synchronously with the changes in the surface water hydrology. Deep convection processes may have occurred in areas not affected by the salinity decrease. Soon after HL4 ( ∼ 33 ka BP) the δ 13 C distribution was similar to that before the Event. Similarly, a rapid return to initial δ 13 C values was observed at the end of the most clearly defined Heinrich Events (HL5, HL4 and HL1). Comparison between deep circulation patterns corresponding to HL4, the Last Glacial Maximum and Heinrich Event 1 indicates that each of these periods was characterized by a different circulation state associated with changes in convection sites.

  • changes in sea surface hydrology associated with Heinrich Event 4 in the north atlantic ocean between 40 and 60 n
    Earth and Planetary Science Letters, 1997
    Co-Authors: Elsa Cortijo, Jean-claude Duplessy, Laurent Labeyrie, Laurence Vidal, Maurice Arnold, Jeanlouis Turon, Maryline J Vautravers, Mark R Chapman, Mary Elliot, G A Auffret
    Abstract:

    Abstract The changes in distribution of sea surface temperature and salinity in the North Atlantic between 40 and 60°N were reconstructed for the time interval between 40 and 30 kyr BP, which includes the large iceberg discharge Event associated with the deposition of Heinrich layer 4. We found that the meltwater input during deposition of Heinrich layer 4 resulted in a 1–2 kyr temperature decrease of about 2°C and a salinity decrease in the range of 1.5‰–3.5‰ between 40 and 50°N. Sites above 50°N did not experience significant salinity variations. A much larger area was affected by the reduction in sea surface temperature. The amplitude of the sea surface temperature shift was, however, much smaller than the atmospheric temperature changes over Greenland at GISP and GRIP sites.

Hai Cheng - One of the best experts on this subject based on the ideXlab platform.

  • oldest dryas hydroclimate reorganization in the eastern iberian peninsula after the iceberg discharges of Heinrich Event 1
    Quaternary Research, 2021
    Co-Authors: Carlos Perezmejias, Hai Cheng, Isabel Cacho, Ana Moreno, Juan Luis Bernalwormull, Cinta M Osacar, Lawrence R Edwards
    Abstract:

    This study examines the first precisely dated and temporally highly resolved speleothem record from Iberia that reconstructs the Oldest Dryas (OD). The onset of cold conditions in the study area, contemporary with the beginning of Heinrich Stadial 1, is recorded at 18.13 ± 0.08 ka, with a pronounced drop of 6.1‰ in δ13C in 250 years. Henceforth, stadial conditions depict a period of instability in the Atlantic Meridional Overturning Circulation, peaking in freshwater input from iceberg melting during Heinrich Event 1. Anomalies in the δ18O of the stalagmite attributed to such a freshwater Event are found from 16.17 to 15.89 ka. Such absolute dates given to the onset of the OD in Iberia and to the main iceberg discharges are reliable anchor points for non-absolute chronologies. Two periods are identified in the OD: OD-a (18.13–16.17 ka) is characterized by wet conditions and a faster growth rate, and OD-b (15.89–14.81 ka) exhibits relative dryness and a slower growth rate. The sudden release of fresh water is considered to be the reason for the disruption of rainfall patterns in eastern Iberia. The present study also highlights the existence of heterogeneous and complex hydrological conditions during the OD in Iberia when both Atlantic and Mediterranean realms are considered.

  • east asian summer monsoon variations during the last deglaciation recorded from a stalagmite at linyi northern china
    Quaternary International, 2017
    Co-Authors: Minte Chen, Hai Cheng, Dong Ding, Lulu Qiao, Qiang Zhang, Yang Zhang, Haoyin Wang, Jianxiong Min, Liyan Wang
    Abstract:

    Abstract A230Th-dated stalagmite record from Linyi, Shandong Province, provides a detailed history of the East Asian summer monsoon (EASM) in northern China during the last deglaciation. Our record reveals changes that are similar to previously published stalagmite records from the East Asian monsoon region on centennial and millennial scales, although some subtle and detail discrepancies are observed. Comparisons with other paleoclimate records show that the EASM was jointly controlled by the North Atlantic climate and low-latitude tropical processes during the last deglaciation. Ocean-atmospheric interactions, particularly sea surface temperature changes in the tropical Pacific might have contributed to the increasing trend of the EASM during the Bolling-Allerod and to the lesser weakening in the EASM during the Younger Dryas. In addition, the significantly higher growth rates of the stalagmite during the Heinrich Event 1 might have been driven by the CO2 degassing processes. Future studies with long-term monitoring of the calcite deposition rate at this site will be needed to support our arguments on the CO2 degassing processes.

  • a quick cooling Event of the east asian monsoon responding to Heinrich Event 1 evidence from stalagmite δ18o records
    Science in China Series D: Earth Sciences, 2002
    Co-Authors: Yongjin Wang, Dianbing Liu, Yanjun Cai, Hai Cheng
    Abstract:

    Based on TIMS U-series dating results and annual band counting method, an annual-resolution time scale from 17450 to 14420 aBP has been established for a stalagmite from the Hulu Cave at Tangshan, Nanjing. A high-resolution oxygen isotopic record reveals decadral-centural oscillations in air temperature in the East Asian monsoon climate area during the last glacial maximum. The most conspicuous feature in the oxygen isotopic record in the period is the particular cold Event synchronized with the last Heinrich Event (H1) in the northern Atlantic deep-sea records. This particular cold Event, beginning at 16140 ± 100 aBP, shows a rapid cooling down with a magnitude of 7–8°C in air temperature within 36 years. Furthermore, δ18O record demonstrates that the Event lasted 790 years with gradually warming tendency (10 cycles of air temperature oscillations) after the remarkable cooling down. We believed that this unique pattern of Event recorded in the stalagmite δ8O might be controlled by various factors including changes of insolation at mid-latitude Northern Hemisphere, the southern extend of the last ice-rafted Event in the North Atlantic and changes of the Equatorial Pacific sea surface temperature.

Helmut Erlenkeuser - One of the best experts on this subject based on the ideXlab platform.

  • Warmings in the far northwestern Pacific promoted pre-Clovis immigration to America during Heinrich Event 1
    Geology, 2006
    Co-Authors: Michael Sarnthein, Thorsten Kiefer, Pieter Meiert Grootes, Henry Elderfield, Helmut Erlenkeuser
    Abstract:

    Well-dated multidecadal- to centennial-scale sediment records from the subarctic northwest Pacific show that the early deglacial 18.5–15.0 ka was marked by 3 pronounced short-term warmings of ~5 °C. They lasted 500–1500 yr each and were coeval with early to late stages of cold Heinrich Event 1 in the North Atlantic. These regional climate windows may have promoted a pre-Clovis emigration of people from the cold-arid monsoon climate in East Asia to the climatically more favorable, then-emerged Beringian and Aleutian shelf regions and the Americas, as suggested by archeological findings.

Biagio Giaccio - One of the best experts on this subject based on the ideXlab platform.

  • high precision 14c and 40ar 39ar dating of the campanian ignimbrite y 5 reconciles the time scales of climatic cultural processes at 40 ka
    Scientific Reports, 2017
    Co-Authors: Biagio Giaccio, Roberto Isaia, Irka Hajdas, Alan L Deino, Sebastien Nomade
    Abstract:

    The Late Pleistocene Campanian Ignimbrite (CI) super-eruption (Southern Italy) is the largest known volcanic Event in the Mediterranean area. The CI tephra is widely dispersed through western Eurasia and occurs in close stratigraphic association with significant palaeoclimatic and Palaeolithic cultural Events. Here we present new high-precision 14C (34.29 ± 0.09 14C kyr BP, 1σ) and 40Ar/39Ar (39.85 ± 0.14 ka, 95% confidence level) dating results for the age of the CI eruption, which substantially improve upon or augment previous age determinations and permit fuller exploitation of the chronological potential of the CI tephra marker. These results provide a robust pair of 14C and 40Ar/39Ar ages for refining both the radiocarbon calibration curve and the Late Pleistocene time-scale at ca. 40 ka. In addition, these new age constraints provide compelling chronological evidence for the significance of the combined influence of the CI eruption and Heinrich Event 4 on European climate and potentially evolutionary processes of the Early Upper Palaeolithic.

  • high precision 14 c and 40 ar 39 ar dating of the campanian ignimbrite y 5 reconciles the time scales of climatic cultural processes at 40 ka
    Scientific Reports, 2017
    Co-Authors: Biagio Giaccio, Roberto Isaia, Irka Hajdas, Alan L Deino, Sebastien Nomade
    Abstract:

    The Late Pleistocene Campanian Ignimbrite (CI) super-eruption (Southern Italy) is the largest known volcanic Event in the Mediterranean area. The CI tephra is widely dispersed through western Eurasia and occurs in close stratigraphic association with significant palaeoclimatic and Palaeolithic cultural Events. Here we present new high-precision 14C (34.29 ± 0.09 14C kyr BP, 1σ) and 40Ar/39Ar (39.85 ± 0.14 ka, 95% confidence level) dating results for the age of the CI eruption, which substantially improve upon or augment previous age determinations and permit fuller exploitation of the chronological potential of the CI tephra marker. These results provide a robust pair of 14C and 40Ar/39Ar ages for refining both the radiocarbon calibration curve and the Late Pleistocene time-scale at ca. 40 ka. In addition, these new age constraints provide compelling chronological evidence for the significance of the combined influence of the CI eruption and Heinrich Event 4 on European climate and potentially evolutionary processes of the Early Upper Palaeolithic.

  • quantifying volcanic ash dispersal and impact of the campanian ignimbrite super eruption
    Geophysical Research Letters, 2012
    Co-Authors: Antonio Costa, Biagio Giaccio, Roberto Isaia, Arnau Folch, G Macedonio, Victoria C Smith
    Abstract:

    [1] We apply a novel computational approach to assess, for the first time, volcanic ash dispersal during the Campanian Ignimbrite (Italy) super-eruption providing insights into eruption dynamics and the impact of this gigantic Event. The method uses a 3D time-dependent computational ash dispersion model, a set of wind fields, and more than 100 thickness measurements of the CI tephra deposit. Results reveal that the CI eruption dispersed 250–300 km 3 of ash over 3.7 million km 2 . The injection of such a large quantity of ash (and volatiles) into the atmosphere would have caused a volcanic winter during the Heinrich Event 4, the coldest and driest climatic episode of the Last Glacial period. Fluorine-bearing leachate from the volcanic ash and acid rain would have further affected food sources and severely impacted Late Middle-Early Upper Paleolithic groups in Southern and Eastern Europe. Citation: Costa, A., A. Folch, G. Macedonio, B. Giaccio, R. Isaia, and V. C. Smith (2012), Quantifying volcanic ash dispersal and impact of the Campanian Ignimbrite super-eruption, Geophys. Res. Lett., 39, L10310, doi:10.1029/2012GL051605.

  • from the bay of naples to the river don the campanian ignimbrite eruption and the middle to upper paleolithic transition in eastern europe
    Journal of Human Evolution, 2008
    Co-Authors: John F Hoffecker, Vance T Holliday, M V Anikovich, A A Sinitsyn, Vasil V Popov, Sergey N Lisitsyn, G M Levkovskaya, G A Pospelova, Steven L Forman, Biagio Giaccio
    Abstract:

    The Campanian Ignimbrite (CI) eruption, dated by 40 Ar/ 39 Ar and various stratigraphic methods to ca. 39,000 cal BP, generated a massive ash plume from its source in southern Italy across Southeastern and Eastern Europe. At the Kostenki-Borshchevo open-air sites on the Middle Don River in Russia, Upper Paleolithic artifact assemblages are buried below, within, and above the CI tephra (which is redeposited by slope action at most sites) on the second terrace. Luminescence and radiocarbon dating, paleomagnetism, and soil and pollen stratigraphy provide further basis for correlation with the Greenland and North Atlantic climate stratigraphy. The oldest Upper Paleolithic occupation layers at Kostenki-Borshchevo may be broadly correlated with warm intervals that preceded the CI Event and Heinrich Event 4 (HE4; Greenland Interstadial: GI 12–GI 9) dating to ca. 45,000–41,000 cal BP. These layers contain an industry not currently recognized in other parts of Europe. Early Upper Paleolithic layers above the CI tephra are correlated with HE4 and warm intervals that occurred during 38,000–30,000 cal BP (GI 8–GI 5), and include an assemblage that is assigned to the Aurigancian industry, associated with skeletal remains of modern humans.

  • the campanian ignimbrite eruption Heinrich Event 4 and palaeolithic change in europe a high resolution investigation
    Geophysical monograph, 2003
    Co-Authors: Francesco G Fedele, Biagio Giaccio, Roberto Isaia, G Orsi
    Abstract:

    The Campanian Ignimbrite (CI) eruption from the Phlegraean Fields Caldera, southern Italy, represents one of the largest late Quaternary volcanic Event. Its recent dating at 39,280±110 yr BP draws attention to the occurrence of this volcanic catastrophe during a time interval characterized by biocultural modifications in western Eurasia. These included the Middle to Upper Palaeolithic transition and the supposed change from Neandertal to modern Homo sapiens anatomy, a subject of continuing investigation and controversy. The paper aims to clarify the position and relevance of the CI Event in this context. At several archaeological sites of southeastern Europe, the CI ash separates the cultural layers containing Middle Palaeolithic and/or Earliest Upper Palaeolithic assemblages from the layers in which Upper Palaeolithic industries occur. At the same sites the CI tephra coincides with a long interruption of occupation. The palaeclimatic records containing the CI products show that the eruption occurred just at the beginning of Heinrich Event 4 (HE4), which was characterized by extreme climatic conditions, compared to the other HEs. From the observation of this concurrence of factors, we advance the hypothesis of a positive climate-volcanism feedback triggered by the co-occurrence of the CI eruption and HE4 onset. Both the environmental and cultural data available for a c.5000-year interval on either side of the Event, suggest that a reappraisal of the identity and destiny of the archaeological industries representing the so-called Middle to Upper Palaeolithic transition is in order. This might force a reassessment of the Upper Palaeolithic notion as traditionally employed.

B C Ward - One of the best experts on this subject based on the ideXlab platform.