Search results for "Global changes"
showing 10 items of 533 documents
Vers l'Amérique : l'implantation médiévale scandinave de la côte sud-ouest du Groenland. Approches historiques et premiers résultats des études paléo…
2011
International audience; During the Viking Age (ca AD 800-1100) Scandinavian explorers settled the islands of the western North Atlantic, making the northernmost agricultural area of the medieval period. Expansion to south-west coast of Greenland at the end of the tenth century brought Norse settlers closer to the limits of their European-style agricultural systems. In response to the harsh low arctic climate, the Greenland Norse have adapted their farming strategies and changed their subsistence pattern, giving a more important place to hunting and fishing. This evolution had probably been accelerated by climatic changes of the Little Ice Age. A good knowledge of the Greenland Norse economy…
Vitesse et cyclicité de fonctionnement des failles normales de rift : implication sur le remplissage stratigraphique des bassins et sur les modalités…
2002
Les objectifs de ce travail sont les suivants. 1- Reconstitution de la géométrie syn-rift du demi-graben de Bourg-d 'Oisans 2- Quantification des vitesses de fon ctionnement des failles normales syn-rift 3- Relation entre vitesse de fonctionnement et processus de croissance des failles normales dans la croûte continentale 4- Reconstitution de la géométrie profonde des failles normales 5- Caractérisation des facteurs de contrôle de l'étirement crustal en contexte de rift 6- Variabilité spatiale et temporelle de l'étirement sur une paléomarge. Secteur d'étude Pour répondre aux différentes problématiques évoquées ci-dessus, le choix du secteur d'étude s'est porté sur le bassin de Bourg-d'Oisan…
Recent changes in measured wind in the NE Atlantic and variability of correlation with NAO
2010
The paper deals with wind measurements, recorded since the 1950s, at twelve meteorological stations along a transect near the westernmost European border, between 64° and 44° N. Extreme wind speed tends to decrease sharply near the northern boundary (at Reykjavick), near the middle of the study area (at Shannon and Valentia) and near the southern boundary (at Brest and Cap Ferret), to increase at Thorshavn, with less significant trends at the other stations. Average wind speeds confirm the above tendencies, with an additional increasing speed at Lerwick, Kirkwall, Malin Head, Belle-Ile and Cap Ferret. To compare changes in wind activity, the data have been subdivided into three periods: unt…
Air-sea interaction in the Central Mediterranean: are surge-generating winds changing ?
2009
International audience; Hourly sea surges from the records of 9 French and 19 Italian tide-gauge stations have been computed and the wind directions corresponding to significant surge heights have been determined. The frequency of such surge-related wind directions tends to increase almost everywhere, while extreme wind speeds (that are most effective to produce high surges) tend generally to decrease; this may be a consequence of the northward displacement of storm trajectories on the European area. There is, however, an exception in the Gulf of Lions (the most westward area considered), where surge height may reach higher elevations, with a recent dangerous increase of southerlies
Soil erosion rates in Burgundian vineyards.
2006
Burgundian vineyards are affected by erosion phenomena that induce sediment transfer along hillslopes. The vineyard under study has occupied the western Bressan rift border for 1000 years, benefiting from marly limestone bedrock and its silt-sand covering. The combined effects of rainstorms and monoculture on slopes reaching 25°, induce a high level of erosion in the arable soil layer. Quantification of erosion rates on a pluri-decennial scale, using vine roots'as a palaeo-surface marker, has been performed on three parcels on three sites along the Côtes-de-Nuits and Côtes-de-Beaune. Assessed erosion rates of around 1 mm.yr-1 characterise current erosive dynamics involving a critical situat…
Retrievals of soil moisture and optical depth from CAROLS
2011
International audience; We propose in this paper to evaluate a method to retrieve soil moisture (SM) and vegetation optical thickness, in areas of unknown roughness and unknown vegetation water content in view of operational applications, by using airborne Tb measurements acquired in South-West of France. Results are compared to in situ measurements, manual and automatic ones included in SMOSmania network, in the South-West of France.
Projet CHIROLUM. Comment limiter les impacts écologiques de l’éclairage artificiel nocturne le long des ILTe ? Caractérisation de l’influence des par…
2021
Ce rapport expose les résultats du projet Chirolum ayant pour objectif d'identifier des pistes de réduction des impacts écologiques de l'éclairage artificiel le long des infrastructures de transport. En prenant l'exemple de sites d'études le long de lisières forestières aux Pays-Bas et le long du Canal du Midi à Toulouse, les résultats montrent que la lumière perturbe fortement l'usage de ces continuités écologiques et infrastructures de transport par les chauves-souris, engendrant des modifications dans le comportement de vol et potentiellement des coûts énergétiques supplémentaires, ainsi qu'une diminution de la connectivité fonctionnelle pour ces espèces potentiellement préjudiciables à …
Distribution models and environmental changes : Application to echinoid faunas in the Southern Ocean and ecoregionalization
2018
Current environmental changes, which impact marine environments, cover major scientific and societal issues, especially as these environmental changes are expected to accelerate along the 21st century. Understanding and forecasting the response of marine biodiversity to these changes is a pregnant scientific issue. Biogeographic and macroecological approaches provide a scientific framework for that purpose. They allow describing and understanding species distribution patterns at large spatial scale as well as estimating their potential shift with regards to environmental change. This is particularly true in the Southern Ocean, where the effects of climate change are already occurring and wh…
The impact of urban contamination on antibioresistance in microbial communities from periphyton and sediments
2020
International audience; Since the early 20's antibiotics have been massively produced and consumed for the benefit of bothhuman and animal health. Nevertheless, antibiotics have also reached the aquatic environmentthrough diffuse sources (e.g. veterinary treatment, contaminated manure application...) and throughwastewater. Consequently, antibiotics concentrations between the ng/L and μg/L range are regularlydetected in surface water and those molecules have also been found in sediments and aquatic biota.The ubiquitous presence of antibiotics exerts a selective pressure on microbial communities leading tothe acquisition and dissemination of antibioresistance in the environment. While both an…
When past human activities impact present-day environment: tracking geochemical anomalies from ancient mines in the Northern French Alps
2017
International audience