121 research outputs found

    Abrupt intrinsic and extrinsic responses of southwestern Iberian vegetation to millennial-scale variability over the past 28 ka

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    We present new high-resolution pollen records combined with palaeoceanographic proxies from the same samples in deep-sea cores SHAK06-5K and MD01-2444 on the southwestern Iberian Margin, documenting regional vegetation responses to orbital and millennial-scale climate changes over the last 28 ka. The chronology of these records is based on high-resolution radiocarbon dates of monospecific samples of the planktonic foraminifera Globigerina bulloides, measured from SHAK06-5K and MD01-2444 and aligned using an automated stratigraphical alignment method. Changes in temperate and steppe vegetation during Marine Isotope Stage 2 are closely coupled with sea surface temperature (SST) and global ice-volume changes. The peak expansion of thermophilous woodland between ~10.1 and 8.4 cal ka bp lags behind the boreal summer insolation maximum by ~2 ka, possibly arising from residual high-latitude ice-sheets into the Holocene. Rapid changes in pollen percentages are coeval with abrupt transitions in SSTs, precipitation and winter temperature at the onset and end of Heinrich Stadial 2, the ice-rafted debris event and end of Heinrich Stadial 1, and the onset of the Younger Dryas, suggesting extrinsically forced southwestern Iberian ecosystem changes by abrupt North Atlantic climate events. In contrast, the abrupt decline in thermophilous elements at ~7.8 cal ka bp indicates an intrinsically mediated abrupt vegetation response to the gradually declining boreal insolation, potentially resulting from the crossing of a seasonality of precipitation threshold

    Abrupt intrinsic and extrinsic responses of southwestern Iberian vegetation to millennial-scale variability over the past 28 ka

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    ABSTRACT: We present new high‐resolution pollen records combined with palaeoceanographic proxies from the same samples in deep‐sea cores SHAK06‐5K and MD01‐2444 on the southwestern Iberian Margin, documenting regional vegetation responses to orbital and millennial‐scale climate changes over the last 28 ka. The chronology of these records is based on high‐resolution radiocarbon dates of monospecific samples of the planktonic foraminifera Globigerina bulloides, measured from SHAK06‐5K and MD01‐2444 and aligned using an automated stratigraphical alignment method. Changes in temperate and steppe vegetation during Marine Isotope Stage 2 are closely coupled with sea surface temperature (SST) and global ice‐volume changes. The peak expansion of thermophilous woodland between ~10.1 and 8.4 cal ka bp lags behind the boreal summer insolation maximum by ~2 ka, possibly arising from residual high‐latitude ice‐sheets into the Holocene. Rapid changes in pollen percentages are coeval with abrupt transitions in SSTs, precipitation and winter temperature at the onset and end of Heinrich Stadial 2, the ice‐rafted debris event and end of Heinrich Stadial 1, and the onset of the Younger Dryas, suggesting extrinsically forced southwestern Iberian ecosystem changes by abrupt North Atlantic climate events. In contrast, the abrupt decline in thermophilous elements at ~7.8 cal ka bp indicates an intrinsically mediated abrupt vegetation response to the gradually declining boreal insolation, potentially resulting from the crossing of a seasonality of precipitation threshold

    Enhanced climate instability in the North Atlantic and southern Europe during the Last Interglacial

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    Considerable ambiguity remains over the extent and nature of millennial/centennial-scale climate instability during the Last Interglacial (LIG). Here we analyse marine and terrestrial proxies from a deep-sea sediment sequence on the Portuguese Margin and combine results with an intensively dated Italian speleothem record and climate-model experiments. The strongest expression of climate variability occurred during the transitions into and out of the LIG. Our records also document a series of multi-centennial intra-interglacial arid events in southern Europe, coherent with cold water-mass expansions in the North Atlantic. The spatial and temporal fingerprints of these changes indicate a reorganization of ocean surface circulation, consistent with low-intensity disruptions of the Atlantic meridional overturning circulation (AMOC). The amplitude of this LIG variability is greater than that observed in Holocene records. Episodic Greenland ice melt and runoff as a result of excess warmth may have contributed to AMOC weakening and increased climate instability throughout the LIG

    Intérêt écologique des galeries de drainage

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    Artificial subterranean habitats can be of important ecological interest. Draining galleries are a typology of artificial springs with underground development characterized by an almost horizontal tunnel that penetrates the side of a slope, to catch the subterranean water and bring it outward. They are a very ancient spring catching technique and provide interesting unstudied subterranean habitats. In this study we surveyed 18 draining galleries in NW Italy. We provide specific environmental data that can help to support broad conclusions on the ecological features and value of these habitats. We found that they house permanent waterbodies, have lengths up to 120 m, are characterized by climatic conditions similar to those of natural caves. We collected several taxa of organisms, adapted to subterranean life as well as coming from outside environment, which find inside draining galleries shelter, roosting and breeding sites. We tested the role of accessibility in determining galleries biodiversity and we found that the latter is scarcely affected. From a conservationist point of view draining galleries can have important ecological value, particularly in areas devoid of natural subterranean habitatsLes environnements souterrains artificiels peuvent être très intéressants d'une point de vue écologique. Les galeries drainantes sont des sources artificielles avec un développement hypogé constitué par une galerie presque horizontale qui s'étend à l'intérieur d'un relief. Il s'agit d'une technique de captage très ancienne qui a créé des habitats souterrains non ou peu étudiés et qui sont potentiellement très intéressants d'un point de vue écologique. Nous avons étudié 18 galeries drainantes dans le nord-ouest de l'Italie. Nous présentons des données écologiques spécifiques qui peuvent aider à formuler des conclusions générales sur les caractéristiques écologiques de ces habitats hypogés. Les galeries drainantes, qui dans la région d'étude atteignent 120 m de longueur, offrent la présence de biotopes humides permanents et ont des caractéristiques climatiques semblables à celles des grottes. Elles constituent des refuges et des sites de reproduction tant à des organismes typiques de la faune cavernicole qu'à beaucoup de taxons provenant de l'extérieur. Nous n'avons pas observé d'influence statistiquement significative de l'accessibilité des sites sur leur niveau de biodiversité. Du point de vue de la conservation les galeries de drainage présentent une valeur écologique certaine, surtout dans les zones dépourvues d'environnements souterrains naturels

    Validation of the Transition Readiness and Appropriateness Measure (TRAM) for the Managing the Link and Strengthening Transition from Child to Adult Mental Healthcare in Europe (MILESTONE) study

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    OBJECTIVE: Young people moving from child and adolescent mental health services (CAMHS) to adult mental health services (AMHS) are faced with significant challenges. To improve this state of affairs, there needs to be a recognition of the problem and initiatives and an urgent requirement for appropriate tools for measuring readiness and outcomes at the transfer boundary (16-18 years of age in Europe). The objective of this study was to develop and validate the Transition Readiness and Appropriateness Measure (TRAM) for assessing a young person's readiness for transition, and their outcomes at the transfer boundary. DESIGN: MILESTONE prospective study. SETTING: Eight European Union (EU) countries participating in the EU-funded MILESTONE study. PARTICIPANTS: The first phase (MILESTONE validation study) involved 100 adolescents (pre-transition), young adults (post-transition), parents/carers and both CAMHS and AMHS clinicians. The second phase (MILESTONE cohort study and nested cluster randomised trial) involved over 1000 young people. RESULTS: The development of the TRAM began with a literature review on transitioning and a review of important items regarding transition by a panel of 34 mental health experts. A list of 64 items of potential importance were identified, which together comprised the TRAM. The psychometric properties of the different versions of the TRAM were evaluated and showed that the TRAM had good reliability for all versions and low-to-moderate correlations when compared with other established instruments and a well-defined factor structure. The main results of the cohort study with the nested cluster randomised trial are not reported. CONCLUSION: The TRAM is a reliable instrument for assessing transition readiness and appropriateness. It highlighted the barriers to a successful transition and informed clinicians, identifying areas which clinicians on both sides of the transfer boundary can work on to ease the transition for the young person. TRIAL REGISTRATION NUMBER: ISRCTN83240263 (Registered 23 July 2015), NCT03013595 (Registered 6 January 2017); Pre-results

    Interglacials of the last 800,000 years

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    Interglacials, including the present (Holocene) period, are warm, low land ice extent (high sea level), end-members of glacial cycles. Based on a sea level definition, we identify eleven interglacials in the last 800,000 years, a result that is robust to alternative definitions. Data compilations suggest that despite spatial heterogeneity, Marine Isotope Stages (MIS) 5e (last interglacial) and 11c (~400 ka ago) were globally strong (warm), while MIS 13a (~500 ka ago) was cool at many locations. A step change in strength of interglacials at 450 ka is apparent only in atmospheric CO2_{2} and in Antarctic and deep ocean temperature. The onset of an interglacial (glacial termination) seems to require a reducing precession parameter (increasing Northern Hemisphere summer insolation), but this condition alone is insufficient. Terminations involve rapid, nonlinear, reactions of ice volume, CO2_{2}, and temperature to external astronomical forcing. The precise timing of events may be modulated by millennial-scale climate change that can lead to a contrasting timing of maximum interglacial intensity in each hemisphere. A variety of temporal trends is observed, such that maxima in the main records are observed either early or late in different interglacials. The end of an interglacial (glacial inception) is a slower process involving a global sequence of changes. Interglacials have been typically 10–30 ka long. The combination of minimal reduction in northern summer insolation over the next few orbital cycles, owing to low eccentricity, and high atmospheric greenhouse gas concentrations implies that the next glacial inception is many tens of millennia in the future.This paper arose as a result of a succession of workshops of the Past Interglacials Group (PIGS), sponsored by the Past Global Changes Project (PAGES). The authors acknowledge the contributions of all participants at those workshops, of whom the listed authors are only a subset. Numerous funding agencies have contributed to the work of this paper including NSF (USA), NERC and The Royal Society (UK), F.R.S –FNRS (Belgium), and SNF (Switzerland). Most data described in this paper are available through relevant data repositories, http://www.ncdc.noaa.gov/data-access/paleoclimatology-data and www.pangaea.de in particular. In addition, the datasets from which Tables 2 and 3 were derived have been compiled into a spreadsheet as a supplement to this paper. Insolation data for Figure 5 can be calculated using programs available at ftp://ftp.elic.ucl.ac.be/berger/berger78/ and ftp://ftp.elic.ucl.ac.be/berger/ellipticintegrals/.  This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/2015RG00048

    Interglacials of the last 800,000 years

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    Interglacials, including the present (Holocene) period, are warm, low land ice extent (high sea level), end‐members of glacial cycles. Based on a sea level definition, we identify eleven interglacials in the last 800,000 years, a result that is robust to alternative definitions. Data compilations suggest that despite spatial heterogeneity, Marine Isotope Stages (MIS) 5e (last interglacial) and 11c (~400 ka ago) were globally strong (warm), while MIS 13a (~500 ka ago) was cool at many locations. A step change in strength of interglacials at 450 ka is apparent only in atmospheric CO2 and in Antarctic and deep ocean temperature. The onset of an interglacial (glacial termination) seems to require a reducing precession parameter (increasing Northern Hemisphere summer insolation), but this condition alone is insufficient. Terminations involve rapid, nonlinear, reactions of ice volume, CO2, and temperature to external astronomical forcing. The precise timing of events may be modulated by millennial‐scale climate change that can lead to a contrasting timing of maximum interglacial intensity in each hemisphere. A variety of temporal trends is observed, such that maxima in the main records are observed either early or late in different interglacials. The end of an interglacial (glacial inception) is a slower process involving a global sequence of changes. Interglacials have been typically 10-30 ka long. The combination of minimal reduction in northern summer insolation over the next few orbital cycles, owing to low eccentricity, and high atmospheric greenhouse gas concentrations implies that the next glacial inception is many tens of millennia in the future

    Trans Fat Consumption and Aggression

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    Background: Dietary trans fatty acids (dTFA) are primarily synthetic compounds that have been introduced only recently; little is known about their behavioral effects. dTFA inhibit production of omega-3 fatty acids, which experimentally have been shown to reduce aggression. Potential behavioral effects of dTFA merit investigation. We sought to determine whether dTFA are associated with aggression/irritability. Methodolgy/Prinicpal Findings: We capitalized on baseline dietary and behavioral assessments in an existing clinical trial to analyze the relationship of dTFA to aggression. Of 1,018 broadly sampled baseline subjects, the 945 adult men and women who brought a completed dietary survey to their baseline visit are the target of this analysis. Subjects (seen 1999– 2004) were not on lipid medications, and were without LDL-cholesterol extremes, diabetes, HIV, cancer or heart disease. Outcomes assessed adverse behaviors with impact on others: Overt Aggression Scale Modified-aggression subscale (primary behavioral endpoint); Life History of Aggression; Conflict Tactics Scale; and self-rated impatience and irritability. The association of dTFA to aggression was analyzed via regression and ordinal logit, unadjusted and adjusted for potential confounders (sex, age, education, alcohol, and smoking). Additional analyses stratified on sex, age, and ethnicity, and examined the prospective association. Greater dTFA were strongly significantly associated with greater aggression, with dTFA more consistently predictive than other assessed aggression predictors. The relationship was upheld wit

    The ACER pollen and charcoal database: A global resource to document vegetation and fire response to abrupt climate changes during the last glacial period

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    This is the final version of the article. Available from Copernicus Publications via the DOI in this record.Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15ka) with a temporal resolution better than 1000years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (14C, 234U/230Th, optically stimulated luminescence (OSL), 40Ar/39Ar-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft Access™ at https://doi.org/10.1594/PANGAEA.870867.The members of the ACER project wish to thank the QUEST-DESIRE (UK and France) bilateral project, the INQUA International Focus Group ACER and the INTIMATE-COST action for funding a suite of workshops to compile the ACER pollen and charcoal database and the workshop on ACER chronology that allow setting the basis for harmonizing the chronologies. Josué M. Polanco-Martinez was funded by a Basque Government postdoctoral fellowship (POS_2015_1_0006) and Sandy P. Harrison by the ERC Advanced Grant GC2.0: unlocking the past for a clearer future
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