Search results for "climate"
showing 10 items of 4934 documents
Pleistocene paleoenvironmental reconstructions and mammalian evolution in South-East Asia: focus on fossil faunas from Thailand.
2006
16 pages; International audience; Mammalian faunal studies have provided various clues for a better reconstruction of hominid Quaternary paleoenvironments. Inthis work, two methods were used: (1) the cenogram method, based on a graphical representation of the mammalian communitystructure, and (2) the species richness of murine rodents to estimate climatic parameters. These methods were applied to Middle andLate Pleistocene mammalian faunas of South-East Asia, from South China to Indonesia. Special emphasis was laid on a fauna fromnorth-east Thailand dated back to approximately 170,000 years (i.e. a glacial period). This Thai fauna seems characteristic of aslightly open forested environment …
History of the reindeer (Rangifer tarandus) in the eastern Baltic region and its implications for the origin and immigration routes of the recent nor…
2006
A total of 45 subfossil reindeer (Rangifer tarandus) antlers and bones - artefacts excluded - have been found over the years in the Baltic countries of Estonia, Latvia and Lithuania. The relatively high number of specimens suggests a stable residence of the species in the eastern Baltic region. For the first time, 12 of these finds were radiocarbon-dated. The ages of the samples range between 12085 and 9970 C-14 yr BP (14180-11280 cal. yr BP), and cover the Lateglacial and early Holocene, a time period during which climatic conditions shifted from periglacial to temperate. The dates suggest a rapid colonization of the area during the deglaciation period and a local extinction around the Ple…
Volcanic climate forcing preceding the inception of the Younger Dryas: Implications for tracing the Laacher See eruption
2021
Climatic warming from the last glacial maximum to the current interglacial period was punctuated by a similar to 1300 years long cold period, commonly referred to as the Younger Dryas (YD). Several hypotheses have been proposed for the mechanism triggering the abrupt inception of the YD, including freshwater forcing, an extra-terrestrial impact, and aerosols from volcanic eruptions. Here, we use synchronised sulphate and sulphur records from both Greenland and Antarctic ice cores to reconstruct volcanic forcing between 13,200-12,800 a BPGICC05 (years before 1950 CE on the Greenland Ice Core Chronology 2005; GICC05). This continuous reconstruction of stratospheric sulphur injections highligh…
Captación y selección de materias primas en la primera metalurgia del Sureste de la península ibérica
2020
The authors are grateful for the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF). We are also in debt with Eduardo Galán, Ruth Maicas and Carmen Cacho, curators of the Museo Arqueológico Nacional (Madrid) for facilitating the sampling and study of metal objects as well as with Ignacio Soriano Llopis for his help on the selection and sampling of the Palmela points, with Massimo Chiaradia who performed the analyses of the Palmela points at the Department of Earth Sciences (University of Geneva, Switzerland) and with Óscar García Vuelta for his pictures of some assemblages. We also appreciate and the careful work of editing and style of the TP edit…
Environmental responses of past and recent agropastoral activities on south Greenlandic ecosystems through molecular biomarkers
2016
Paleoenvironmental studies previously performed on Lake Igaliku revealed two agropastoral phases in south Greenland: the Norse settlement from AD 986 to ca. AD 1450 and the recent installation of sheep farmers, since the 1920s. To improve the knowledge of the timing and magnitude of the Greenlandic agropastoral activities, a lipid inventory was realized and compared with biological and geochemical data. During the 12th century, a major increase in deoxycholic acid (DOC) and coprophilous fungal spores revealed a maximum of herbivores. Synchronously, a minimum of the n-C29/ n-C31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and s…
Diving into the Past: A Paleo Data–Model Comparison Workshop on the Late Glacial and Holocene
2019
Understanding changes in the climate of the late Pleistocene and the Holocene has long been a research topic. Studies rely on different sources of information, ranging from terrestrial and marine archives to a hierarchy of climate modeling activities. In contrast to the climate of the last millennium, novel approaches are necessary to bridge the different temporal and spatial representations of the various archives and the climate models, and to achieve a robust understanding of climate variability and climate processes on centennial-to-millennial time scales.
Causes and consequences of past and projected Scandinavian summer temperatures, 500-2100 AD
2011
Tree rings dominate millennium-long temperature reconstructions and many records originate from Scandinavia, an area for which the relative roles of external forcing and internal variation on climatic changes are, however, not yet fully understood. Here we compile 1,179 series of maximum latewood density measurements from 25 conifer sites in northern Scandinavia, establish a suite of 36 subset chronologies, and analyse their climate signal. A new reconstruction for the 1483–2006 period correlates at 0.80 with June–August temperatures back to 1860. Summer cooling during the early 17th century and peak warming in the 1930s translate into a decadal amplitude of 2.9°C, which agrees with existin…
Characterization of the Medieval Climate Anomaly, Little Ice Age and recent warming in northern Lapland
2017
The major climate events of the Common Era (CE) have global imprints but significant variations in their timing and magnitude have been suggested. For reliable assessments of the past climate patterns and their applications for evaluations of the ongoing changes, spatially comprehensive network of high-fidelity paleorecords are necessary. In this study, we reconstruct summer air temperatures of the past 2000 years from northern Lapland (Utsjoki, Finland). We use fossil Chironomidae (Diptera) assemblages from sediments of a remote subarctic lake (Loažžejavri) and the transfer function approach for quantitative temperature reconstruction. The results indicate that the Chironomidae fauna were …
Astrochronology of the Valanginian Stage from reference sections (Vocontian Basin, France) and palaeoenvironmental implications for the Weissert Even…
2013
12 pages; International audience; High-resolution gamma-ray measurements performed on five biostratigraphically well-dated reference sections from the Vocontian Basin (south-eastern France) are used to develop a new astrochronology of the Valanginian Stage and its subdivisions (i.e. ammonite and calcareous nannofossil zones and subzones). Spectral analyses show a pervasive dominance of 405-kyr eccentricity cycles with the expression of 100-kyr eccentricity, obliquity and precession. Previous rough estimates of Valanginian Stage duration ranged from 3.9 to 6.5 myr but were generally based on less reliable or indirect methods. This study provides a precise duration of 5.08 myr, tuning the ser…
Record of latest Barremian-Cenomanian environmental change in tectonically controlled depressions from the Jura-Burgundy threshold (Jura Mountains, e…
2019
Abstract The area of the western Jura Mountains constitutes the former Jura-Burgundy threshold between the Tethys Ocean and the epicontinental Paris Basin Sea. During the Barremian, the area was covered by a shallow-water Urgonian carbonate platform. Tectonic processes influenced the architecture of the Urgonian platform and were notably responsible for the formation of fault-related depressions on top of the Urgonian series, which were subsequently transformed into incised valleys and then to marine depocenters. Their sedimentary infills are mostly represented by the Perte-du-Rhone Formation and record stepwise environmental change on the innermost platform, which was strongly influenced b…