495 research outputs found

    Quantifying recent acceleration in sea level unrelated to internal climate variability

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    Sea level observations suggest that the rate of sea level rise has accelerated during the last 20?years. However, the presence of considerable decadal-scale variability, especially on a regional scale, makes it difficult to assess whether the observed changes are due to natural or anthropogenic causes. Here we use a regression model with atmospheric pressure, wind, and climate indices as independent variables to quantify the contribution of internal climate variability to the sea level at nine tide gauges from around the world for the period 1920–2011. Removing this contribution reveals a statistically significant acceleration (0.022?±?0.015?mm/yr2) between 1952 and 2011, which is unique over the whole period. Furthermore, we have found that the acceleration is increasing over time. This acceleration appears to be the result of increasing greenhouse gas concentrations, along with changes in volcanic forcing and tropospheric aerosol loading

    Icnología de vertebrados de la facies Buntsandstein de Mallorca

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    Se describen, por primera vez en Mallorca, hasta cinco tipos diferentes de icnitas y pistas de vertebrados continentales dentro de las facies  cuarzoareniticas y limosas rojas de la facies Buntsandstein del Triásico inferio

    Icnología de vertebrados de la facies Buntsandstein de Mallorca

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    Se describen, por primera vez en Mallorca, hasta cinco tipos diferentes de icnitas y pistas de vertebrados continentales dentro de las facies  cuarzoareniticas y limosas rojas de la facies Buntsandstein del Triásico inferio

    Mating rituals of the Indigo Snake

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    This is where the abstract of this record would appear. This is only demonstration data

    Icnología de vertebrados de las facies Buntsandstein de Mallorca

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    Se describen, por primera vez en Mallorca, hasta cinco tipos diferentes de icnitas y pistas de vertebrados continentales dentro de las facies cuarzoareniticas y limosas rojas de la facies Buntsandstein del Triásico inferio

    The Geology of Chile

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    6 páginas.-- Book review of "The Geology of Chile", by Teresa Moreno and Wes Gibbons (eds.) (2007). Geological Society. London (United Kingdom). 414 pages, 286 figures including maps, charts and pictures; 27, 5 x 21 cm, ISBN 978-1- 86239-219-9 (hardback) and ISBN 978-1-86239-220-5 (softback).Peer reviewe

    Transient erosion in the Valencia Trough turbidite systems, NW Mediterranean Basin

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    12 pages, 9 figuresSubmarine canyons can efficiently drain sediments from continental margins just as river systems do in subaerial catchments. Like in river systems, submarine canyons are often arranged as complex drainage networks that evolve from patterns of erosion and deposition. In the present paper we use a morphometric analysis of submarine canyon-channel long-profiles to study the recent sedimentary history of the Valencia Trough turbidite system (VTTS) in the NW Mediterranean Sea. The VTTS is unique in that it drains sediment from margins with contrasting morphologies through a single “trunk” conduit, the Valencia Channel. The Valencia Channel has been active since the late Miocene, evolving in response to Plio-Quaternary episodes of erosion and deposition. The integrated analysis of long-profiles obtained from high-resolution bathymetric data across the entire turbidite system shows evidence for transient canyon incision in the form of knickpoints and hanging tributaries. Multiple factors appear to have triggered these periods of incision. These include a large debris flow at 11,500 yr BP that disrupted the upper reaches of the VTTS and glacio-eustatic lowstands that forced shifting of sediment input to the VTTS. Based on these inferences, long-term time-averaged incision rates for the Valencia Channel have been estimated. The evidence we present strongly suggests that Foix Canyon has played a key role in the drainage dynamics of the VTTS in the past. This study builds conceptually on a recent modeling study that provides a morphodynamic explanation for the long-term evolution of submarine canyon thalweg profiles. The procedure and results from this work are of potential application to other submarine sediment drainage systems, past and present, including those containing mid-ocean type valleys like the Valencia ChannelThis research was supported by the HERMIONE project, EC contract 226354-HERMIONE, funded by the European Commission's Seventh Framework Programme, and the HERMES Project, EC contract GOCE-CT-2005-511234, funded by the European Commission's Sixth Framework Programme under the priority “Sustainable Development, Global Change and Ecosystems”. It has also benefited from inputs by the PROMETEO (CTM2007-66316-C02-01/MAR), EDINSED3D (CTM2007-64880/MAR), and the GRACCIE CONSOLIDER (CSD2007-00067) projects, funded by the Spanish RTD Programme. GRC Geociències Marines is supported by Generalitat de Catalunya “Grups de Recerca Consolidats” grant 2009 SGR 1305Peer reviewe

    Sinking diatom assemblages as a key driver for deep carbon and silicon export in the Scotia Sea (Southern Ocean)

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    Physical and biogeochemical processes in the Southern Ocean are fundamental for modulating global climate. In this context, a process-based understanding of how Antarctic diatoms control primary production and carbon export, and hence global ocean carbon sequestration, has been identified as a scientific priority. Here we use novel sediment trap observations in combination with a data-assimilative ocean biogeochemistry model (ECCO-Darwin) to understand how environmental conditions trigger diatom ecology in the iron-fertilized southern Scotia Sea. We unravel the role of diatoms assemblage in controlling the biogeochemistry of sinking material escaping from the euphotic zone, and discuss the link between changes in upper-ocean environmental conditions and the composition of settling material exported from the surface to 1,000 m depth from March 2012 to January 2013. The combined analysis of in situ observations and model simulation suggests that an anomalous sea-ice episode in early summer 2012–2013 favored (via restratification due to sea-ice melt) an early massive bloom of Corethron pennatum that rapidly sank to depth. This event drove high biogenic silicon to organic carbon export ratios, while modulating the carbon and nitrogen isotopic signals of sinking organic matter reaching the deep ocean. Our findings highlight the role of diatom ecology in modulating silicon vs. carbon sequestration efficiency, a critical factor for determining the stoichiometric relationship of limiting nutrients in the Southern Ocean.CTM2009-08287-E/ANT, CTM2011-14056E/ANT, SGR 315 2017info:eu-repo/semantics/publishedVersio
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