Search results for "CLIMATE"
showing 10 items of 4934 documents
Climate change: A driver of future conflicts in the Persian Gulf Region?
2021
Ongoing global change and its direct environmental impacts, in addition to securing economic transition to the post-oil era, could trigger complex socio-economic and political crises in oil-dependent economies of the Persian Gulf Region (PGR). To evaluate the role of climate change and related policies in degrading the environment and its socio-economic impacts in the PGR, we have used a variety of available global datasets and published data. The results show that the countries of the PGR pursue some types of socio-economic reforms to alleviate the impacts of climate change. However, it seems that these attempts are not compatible with the environment's capacity. The main problem stems fro…
Global Groundwater-Vegetation Relations
2017
Groundwater is an integral component of the water cycle, and it also influences the carbon cycle by supplying moisture to ecosystems. However, the extent and determinants of groundwater-vegetation interactions are poorly understood at the global scale. Using several high-resolution data products, we show that the spatial patterns of ecosystem gross primary productivity and groundwater table depth are correlated during at least one season in more than two-thirds of the global vegetated area. Positive relationships, i.e., larger productivity under shallower groundwater table, predominate in moisture-limited dry to mesic conditions with herbaceous and shrub vegetation. Negative relationships, …
Results from DROXO IV. EXTraS discovery of an X-ray flare from the Class I protostar candidate ISO-Oph 85
2016
X-ray emission from Young Stellar Objects (YSOs) is crucial to understand star formation. A very limited amount of X-ray results is available for the protostellar (ClassI) phase. A systematic search of transient X-ray phenomena combined with a careful evaluation of the evolutionary stage offer a widely unexplored window to our understanding of YSOs X-ray properties. Within the EXTraS project, a search for transients and variability in the whole XMM-Newton archive, we discover transient X-ray emission consistent with ISO-Oph 85, a strongly embedded YSO in the rho Ophiuchi region, not detected in previous time-averaged X-ray studies. We extract an X-ray light curve for the flare and determine…
Long-term annual burning of grassland increases CO2 emissions from soils.
2016
7 pages; International audience; Grasslands have potential to mitigate against climate change because of their large capacity to store soil organic carbon (SOC). However, the long-term impact of grassland management such as burning, which is still common in many areas of the world, on SOC is still a matter of debate. The objective of this study was to quantify the long-term effects of annual burning on CO2 output from soils and SOC stocks. The study was performed on a 62 years old field trial comparing annual burning (AB) to no burning associated with tree encroachment (NB), and to annual mowing (AM) with all treatments laid out in randomized block design with three replicates per treatment…
A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation
2011
The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto. It resides at present at 95.7 astronomical units (1ĝ€‰au is the Earth-Sun distance) from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 ut. The event is consistent with a spherical shape for Eris, with radius 1,163±6 kilometres, density 2.52±0.05 grams per cm 3 and a high visible geometric albedo,. No nitro…
Evolution of the neodymium isotopic signature of neritic seawater on a northwestern Pacific margin: new constrains on possible end-members for the co…
2013
11 pages; International audience; The Neodymium(Nd) isotope composition of fish remains has beenwidely used to track past changes in oceanic circulation. Although the number of published Nd isotope data for the Cretaceous has markedly increased in the last years, no consensus has been reached on the structure of the oceanic circulation and its evolution during the Late Cretaceous. Yet this period is characterised bymajor geodynamical and climatic changes andmarked by the disappearance of global oceanic anoxic events inwhich changes in oceanic circulation modesmay have played a significant role. In this study we present the first record of Nd isotopic composition of fish remains from contine…
13C composition of dissolved organic carbon in upland forested catchments of the Morvan Mountains (France): Influence of coniferous and deciduous veg…
2007
10 pages; International audience; One of the main environmental changes caused by human activities is that of land use. These changes influence the quantity and quality of the dissolved organic matter (DOM) fluxes through the vegetation–soil–stream system. The aim of this work is to evaluate the influence of the substitution of native deciduous forests by well managed coniferous forests on dissolved organic carbon (DOC) fluxes and their associated carbon isotopic composition (d13CDOC). DOC fluxes and d13CDOC were monitored for 2 years in the streams of four similar upland forested catchments in the Morvan Mountains (France). Mean annual DOC concentrations and fluxes were 2–4 times lower in …
The Early-Cambrian Boho volcano of the El Graara massif, Morocco: Petrology, geodynamic setting and coeval sedimentation
2006
15 pages; International audience; A major volcanic episode is recorded across the Neoproterozoic-Cambrian transition in the Moroccan Anti-Atlas. Several volcanic cones are still preserved in the El Graara massif, laterally correlatable with volcanic flows dated as Early Cambrian (U/Pb date of 534 ± 10 Ma). Volcanic ashes and flows are interbedded with the uppermost part of the Adoudou dolostones, whereas the best-preserved volcano (the Boho Jbel) is onlapped by the overlying Lie-de-vin strata. Available petro-geochemical data from the Boho volcano suggest an alkaline magmatism probably derived from low-grade melting of a garnet–lherzolite mantle source, followed by fractional crystallizatio…
Occurrence of fossil organic matter in modern environments: optical, geochemical and isotopic evidence
2011
International audience; This study relates to the input and fate of fossil organic matter (FOM) in the modern environment, and focuses on two experimental watersheds overlying Jurassic marls: Le Laval and Le Brusquet (1 km(2) in area), located near Digne, Alpes-de-Haute-Provence, France. Considering that FOM delivery is mainly a result of different processes affecting sedimentary rocks [(bio)chemical and mechanical weathering], samples from different pools were collected: bedrocks, weathering profiles, soils and riverine particles. The samples were examined using complementary techniques: optical (palynofacies methods), geochemical (Rock-Eval 6 pyrolysis, C/N ratio), molecular (gas chromato…
Chlorine Partitioning Between a Basaltic Melt and H2O-CO2 Fluids at Mount Etna
2009
Partitioning experiments between a basaltic melt from Mt. Etna and a low-density hydrous fluid or vapor containing H(2)O or H(2)O-CO(2) were performed at 1200-1260 degrees C, at pressures between 1 and 200 MPa, either near the nickel-nickel oxide (NNO) buffer or at two log units above it (NNO + 2), and with different chloride concentrations. Most of the experiments were done at chloride-brine-undersaturated conditions, although at the highest Cl concentrations explored brine saturation might have been reached. The average partition coefficients (D(Cl)(fluid/melt)) over the range of Cl concentrations were derived on a weight basis by plotting the calculated concentrations of Cl in the fluid …