Search

Your search keyword '"Gaël Durand"' showing total 77 results
Start Over Author "Gaël Durand"
77 results on '"Gaël Durand"'

1. Identification of the Contamination Sources by PCBs Using Multivariate Analyses: The Case Study of the Annaba Bay (Algeria) Basin

Author

Soumeya Khaled-Khodja, Hassen Cheraitia, Karima Rouibah, Hana Ferkous, Gaël Durand, Semia Cherif, Gamal A. El-Hiti, Krishna Kumar Yadav, Alessandro Erto, and Yacine Benguerba

Subjects
urban waste, wastewater, POPs, PCB contamination sources, PCA/HCA, multivariate analysis, Organic chemistry, QD241-441
Abstract

Persistent Organic Pollutants (POPs), particularly the indicator polychlorinated biphenyls (PCBs), were first quantified in water and sediments of two wadis, Boujemaâ and Seybouse, as well as in the effluents from a fertilizer and phytosanitary production industrial plant (Fertial). Since these contaminated discharges end in Annaba Bay (Algeria) in the Mediterranean Sea, with a significant level of contamination, all the potential sources should be identified. In this work, this task is conducted by a multivariate analysis. Liquid–liquid extraction and gas chromatography/mass spectrometry (GC–MS) methods were applied to quantify seven PCB congeners, usually taken as indicators of contamination. The sum of the PCB concentrations in the sediments ranged from 1 to 6.4 μg/kg dw (dry weight) and up to 0.027 μg/L in waters. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for the multivariate analysis, indicating that the main sources of PCB emissions in the bay are urban/domestic and agricultural/industrial. The outfalls that mostly contribute to the pollution of the gulf are the Boujemaâ wadi, followed by the Seybouse wadi, and finally by the Fertial cluster and more precisely the annex basin of the plant. Although referring to a specific site of local importance, the work aims to present a procedure and a methodological analysis that can be potentially applicable to further case studies all over the world.

Published
2023
Full Text
View/download PDF

2. Sea-Level Rise: From Global Perspectives to Local Services

Author

Gaël Durand, Michiel R. van den Broeke, Goneri Le Cozannet, Tamsin L. Edwards, Paul R. Holland, Nicolas C. Jourdain, Ben Marzeion, Ruth Mottram, Robert J. Nicholls, Frank Pattyn, Frank Paul, Aimée B. A. Slangen, Ricarda Winkelmann, Clara Burgard, Caroline J. van Calcar, Jean-Baptiste Barré, Amélie Bataille, and Anne Chapuis

Subjects
sea-level rise, Antarctic, Greenland, glaciers, local impact, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract

Coastal areas are highly diverse, ecologically rich, regions of key socio-economic activity, and are particularly sensitive to sea-level change. Over most of the 20th century, global mean sea level has risen mainly due to warming and subsequent expansion of the upper ocean layers as well as the melting of glaciers and ice caps. Over the last three decades, increased mass loss of the Greenland and Antarctic ice sheets has also started to contribute significantly to contemporary sea-level rise. The future mass loss of the two ice sheets, which combined represent a sea-level rise potential of ∼65 m, constitutes the main source of uncertainty in long-term (centennial to millennial) sea-level rise projections. Improved knowledge of the magnitude and rate of future sea-level change is therefore of utmost importance. Moreover, sea level does not change uniformly across the globe and can differ greatly at both regional and local scales. The most appropriate and feasible sea level mitigation and adaptation measures in coastal regions strongly depend on local land use and associated risk aversion. Here, we advocate that addressing the problem of future sea-level rise and its impacts requires (i) bringing together a transdisciplinary scientific community, from climate and cryospheric scientists to coastal impact specialists, and (ii) interacting closely and iteratively with users and local stakeholders to co-design and co-build coastal climate services, including addressing the high-end risks.

Published
2022
Full Text
View/download PDF

3. Exposure of the French population to bisphenols, phthalates, parabens, glycol ethers, brominated flame retardants, and perfluorinated compounds in 2014–2016: Results from the Esteban study

Author

Clémence Fillol, Amivi Oleko, Abdesattar Saoudi, Abdelkrim Zeghnoun, Alexis Balicco, Jessica Gane, Loïc Rambaud, Alain Leblanc, Éric Gaudreau, Philippe Marchand, Bruno Le Bizec, Valérie Bouchart, Florent Le Gléau, Gaël Durand, and Sébastien Denys

Subjects
Biomonitoring, Children, General population, Environmental exposure, Endocrine disruptor, Esteban, Environmental sciences, GE1-350
Abstract

Background: As part of the French Human Biomonitoring (HBM) programme, the Esteban study described, among other things, biomarkers levels of various chemicals in adults (18–74 years old) and children (6–17 years old). This paper describes the design of the study and provides, for the first time, data on the biological exposure of the general French population to a wide range of contaminants posing a threat to human health which are currently found in domestic environments. Methods: Esteban is a cross-sectional study conducted on a nationwide sample of the French general population. Exposure biomarkers of six families of contaminants deemed detrimental to adults’ and children’s health were measured in biological samples collected either at participants’ homes by a nurse, or brought to a National Health Insurance examination centre. All participants were randomly selected (2503 adults and 1104 children). The geometric mean and percentiles of the distribution of levels were estimated for each biomarker. Most of the descriptive statistical analyses were performed taking into account the sampling design. Results: Results provided a nationwide description of biomarker levels. Bisphenols (A, S and F), and some metabolites of phthalates and perfluorinated compounds (PFCs) (specifically, PFOS and PFOA) were quantified in almost all the biological samples analysed. Higher levels were observed in children (except for PFCs). Levels were coherent with international studies, except for bisphenols S and F, brominated flame retardants (BFRs) and parabens (with higher levels reported in the USA than in France). Conclusion and perspectives: This study is the first to provide a representative assessment of biological exposure to domestic contaminants at the French population level. Our results show that the French general population was exposed to a wide variety of pollutants in 2014–2016, and identify the determinants of exposure. These findings will be useful to stakeholders who wish to advocate an overall reduction in the French population’s exposure to harmful substances. Similar future studies in France will help to measure temporal trends, and enable public policies focused on the reduction of those chemicals in the environment to be evaluated.

Published
2021
Full Text
View/download PDF

4. Sensitivity of grounding line dynamics to the choice of the friction law

Author

JULIEN BRONDEX, OLIVIER GAGLIARDINI, FABIEN GILLET-CHAULET, and GAËL DURAND

Subjects
glacier mechanics, glacier modelling, ice-sheet modelling, subglacial processes, Environmental sciences, GE1-350, Meteorology. Climatology, QC851-999
Abstract

Basal slip accounts for a large part of the flow of ice streams draining ice from Antarctica and Greenland into the ocean. Therefore, an appropriate representation of basal slip in ice flow models is a prerequisite for accurate sea level rise projections. Various friction laws have been proposed to describe basal slip in models. Here, we compare the influence on grounding line (GL) dynamics of four friction laws: the traditional Weertman law and three effective pressure-dependent laws, namely the Schoof, Tsai and Budd laws. It turns out that, even when they are tuned to a common initial reference state, the Weertman, Budd and Schoof laws lead to thoroughly different steady-state positions, although the Schoof and Tsai laws lead to much the same result. In particular, under certain circumstances, it is possible to obtain a steady GL located on a reverse slope area using the Weertman law. Furthermore, the predicted transient evolution of the GL as well as the projected contributions to sea level rise over a 100-year time horizon vary significantly depending on the friction law. We conclude on the importance of choosing an appropriate law for reliable sea level rise projections and emphasise the need for a coupling between ice flow models and physically based subglacial hydrological models.

Published
2017
Full Text
View/download PDF

6. Introducing the French national programme TRACCS: TRAnsformative Advances in Climate modelling for Climate Services

Author

Masa Kageyama, Samuel Morin, Sandrine Anquetin, Nathalie de Noblet, Laurent Terray, Olivier Boucher, Julie Deshayes, Gaël Durand, David Salas y Mélia, Ludovic Bouilloud, and Pascale Braconnot

Abstract

TRACCS (TRAnsformative Advances in Climate modelling for Climate Services) is a new French programme which will start in 2023 and run for the next eight years. TRACCS will combine several types of activities: i) process modelling for simulating climate from global to local scales, so as to provide reliable climate information for assessing both mitigation scenarios and local adaptation actions and their feedback effects on the climate, ii) adaptation of computer codes to new computing architectures, to seize the opportunities offered by exascale in terms of increasing spatial resolution, better representing the complexity of the climate system, and exploring large sets of simulations and obtain better information on model and scenario-related uncertainties, iii) the use of advanced statistical methods and artificial intelligence to characterise climate extremes, accelerate models, and develop emulators (fast statistical models) to better quantify uncertainties, iv) the estimation of the impacts of climate change on different activity sectors and different territories in order to co-construct adaptation, and v) the development of a dialogue between scientists and stakeholders, teaching and communication with all audiences in order to co-construct prototypes of climate services in a transdisciplinary approach. These activities, together with the training of a new generation of experts in climate change and its impacts, have the ambition to transform the way scientific advances on climate change are shared with stakeholders, thereby multiplying the capacity for science-based adaptation and mitigation.The programme is jointly managed by CNRS and Meteo-France and involves key partners (CEA, IRD, CERFACS, Université-Grenoble-Alpes, Sorbonne Université, Université Versailles-Saint-Quentin, Université Paris-Saclay) in modelling and understanding climate change and its potential impacts.Our poster presentation will give us an opportunity to present this new project and build collaborations with similar projects at the European and international level.

Published
2023

7. Save the glaciers! An educational escape kit

Author

Anne Chapuis, Clara Burgard, Etienne Ducasse, Samuel Cook, Léna Gauthier, Cruz Garcia Molina, Amélie Bataille, and Gaël Durand

Abstract

Save the glaciers! is an educational escape kit designed for teenagers (11-18 years old) to learn what glaciers are, how they move, how they react to climate change and what people can do to slow down their melt.We made two versions of the game: a physical version and an online version. In both versions players have to sequentially solve 4 enigmas to unlock the next enigma until they reach the end of the game. Each enigma is designed to make the player discover and understand the following processes: Melting of mountains glaciers contributes to sea level rise Anatomy and mass-balance of a mountain glacier: What is it made of? How does it form? How does it grow and shrink? Glacier sliding: glaciers are not static, they slowly slide under their own weight Mountain glaciers are losing mass all around the world due to climate change, which can be observed by looking at their retreating termini. The physical version is designed to be played by 5 people; the online version can be played alone. Three levels of difficulty have been designed for the physical game: secondary-school pupils, high-school pupils and university students. In total more than 200 people have played the game, across both the physical and online versions.The game has been developed as a collaboration between the H2020 project PROTECT and a team at the Institute of Environmental Geosciences.

Published
2023

8. Cryosphere and sea level rise : A numerical interactive educational activity

Author

Clémence Foucher, Anne Chapuis, Gaël Durand, Jean-Baptiste Barré, and Amélie Bataille

Abstract

Expedition Sea Level - a time travel to unveil the mysteries of sea level rise : becoming an actor of climate change is a numerical interactive activity designed as a game for middle school students (11 - 15 years old) to learn the links between sea level rise, the melt of glaciers and ice sheets, and human activities. This includes various notions to help them understand why sea level changes, how ice sheets and glaciers evolve and are studied, the ideas of uncertain futures, mitigation and adaptation.This activity is to be discovered in group or alone, in class or in scientific facilities when classes come to visit and encounter the actors and actresses of science. Another of its goal is to create discussions and debates among students on various subjects regarding climate change but also to help them understand the scientific processes behind the different changes happening or incoming, in order to fight increasing eco-anxiety.To do so, a fictional narrative is decomposed in three chapters with a growing immersion for the audience. The first one is a short animation staging a young Maldivian girl in 2081, going to see her grandparents whom house is partially underwater. The second one is designed as a first person shooter game where the public plays a glaciologist at Dumont d’Urville and on the Astrolabe glacier, answering pedagogical quizzes and learning through mini games. And the last one is shaped as a multiple choices tree game, leading to three IPCC scenario (low, intermediary and high). The choices made by the player.s lead to one out of the three scenario in which the public needs to find the best adaptation plan to protect the grandparents from the first chapter.Expedition Sea Level is the result of a diploma project conducted alongside the european research project PROTECT. This fully illustrated project answers the communication needs of PROTECT but also the needs of understanding and entertainment expectations of middle school students, based on an anonymous survey conducted among 71 middle school students, mainland France, from December 2021 to February 2022.

Published
2023

11. Contamination and Sources Identification of Polycyclic Aromatic Hydrocarbons in Water and Sediments of Annaba Bay Basin, Algeria

Author

Hassen Cheraitia, Gaël Durand, Semia Cherif, and Soumeya Khaled-Khodja

Subjects
Pollution, geography, geography.geographical_feature_category, media_common.quotation_subject, Contamination, Structural basin, Mediterranean sea, Environmental chemistry, Environmental science, Gas chromatography, Bay, Wadi, Water Science and Technology, media_common
Abstract

Annaba gulf is a coastal area (southwestern Mediterranean Sea) that receives large diffuse inputs from Fertial plant, Seybouse wadi and Boujemaâ wadi, which are influenced by anthropogenic activities. Wastewaters and surface waters and sediments from these sites were analyzed for Polycyclic Aromatic Hydrocarbons (16 PAHs) by using gas chromatography system operating with the flame ionizing detector (FID). Total PAHs ranged from 0.033 to 0.503 µg L–1 in water, and from 32.44 to 509.58 µg kg–1dw in sediments. In order to identify pollution emission sources of PAHs, three source identification techniques were used, including diagnostic ratios, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). The results show that the pollution originated mainly from pyrogenic inputs in water and sediments. Annaba Bay basin is contaminated mainly by heavy PAHs discards originated from domestic and industrial wastewaters and traffic emissions.

Published
2021

12. Prenatal exposure to organophosphate pesticides and autism spectrum disorders in 11-year-old children in the French PELAGIE cohort

Author

Mathilde Lizé, Christine Monfort, Florence Rouget, Gwendolina Limon, Gaël Durand, Hélène Tillaut, Cécile Chevrier, Institut de recherche en santé, environnement et travail (Irset), Université d'Angers (UA)-Université de Rennes (UR)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), CHU Pontchaillou [Rennes], LABOCEA Laboratoire [Plouzané, France], Université d'Angers (UA)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), and École des Hautes Études en Santé Publique [EHESP] (EHESP)

Subjects
Male, Insecticides, Autism Spectrum Disorder, Autism, Autism spectrum disorders, Biochemistry, Prenatal exposure, Organophosphorus Compounds, Pregnancy, Prenatal Exposure Delayed Effects, Diazinon, [SDE]Environmental Sciences, Acetylcholinesterase, Organophosphate pesticides, Humans, Female, [SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie, Chlorpyrifos, Pesticides, Child, Children, General Environmental Science
Abstract

International audience; Background: Organophosphate (OP) pesticides act by inhibiting acetylcholinesterase activity at synaptic junctions and have already been linked with deleterious effects on neurodevelopment, including autism spectrum disorders (ASD).Objectives: To investigate the association of prenatal exposure to OP pesticides with traits related to ASD in 11-year-old children.Methods: The "Childhood Autism Spectrum Test" (CAST) parent questionnaire was used to screen for autistic traits in 792 children from the French PELAGIE cohort. Prenatal maternal urine samples were collected 80%), terbufos and its metabolites least often (

Published
2022

13. Quantifying ambiguity in sea-level projections

Author

Detlef Stammer, Robert J. Nicholls, Aimée B. A. Slangen, Jochen Hinkel, Gonéri Le Cozannet, Jeremy Rohmer, Angélique Melet, Catherine Ritz, Dewi Le Bars, Mark Carson, Erwin Lambert, David Salas y Melia, Jean-Charles Manceau, Benoit Meyssignac, Gaël Durand, Roderik S. W. van de Wal, and Rémi Thiéblemont

Subjects
media_common.quotation_subject, Climatology, Ambiguity, Geology, Sea level, media_common
Abstract

Coastal impacts of climate change and the related mitigation and adaptation needs requires assessments of future sea-level changes. Following a common practice in coastal engineering, probabilistic sea-level projections have been proposed for at least 20 years. This requires a probability model to represent the uncertainties of future sea-level rise, which is not achievable because potential ice sheets mass losses remain poorly understood given the knowledge available today. Here, we apply the principles of extra-probabilistic theories of uncertainties to generate global and regional sea-level projections based on uncertain components. This approach assigns an imprecision to a probabilistic measure, in order to quantify lack of knowledge pertaining to probabilistic projections. This can serve to understand, analyze and communicate uncertainties due to the coexistence of different processes contributing to future sea-level rise, including ice-sheets. We show that the knowledge gained since the 5th Assessment report of the IPCC allows better quantification of how global and regional sea-level rise uncertainties can be reduced with lower greenhouse gas emissions. Furthermore, Europe and Northern America are among those profiting most from a policy limiting climate change to RCP 2.6 versus RCP 4.5 in terms of reducing uncertainties of sea-level rise.

Published
2021

14. Potential Tipping Points of Antarctic Ice Sheet Basins

Author

Lars Zipf, Konstanze Haubner, Sainan Sun, Heiko Goelzer, Frank Pattyn, Gaël Durand, and Kevin Bulthuis

Subjects
Oceanography, Antarctic ice sheet, Geology
Abstract

Antarctica is loosing mass in an accelerating way and these losses are considered as the major source of sea-level rise in the coming centuries. Ice-sheet mass loss is mainly triggered by the decreased buttressing from ice shelves mainly due to ice-ocean interaction. This loss could be self-sustained in potentially unstable regions where the grounded ice lies on a bedrock below sea level sloping down towards the interior of the ice sheet, leading to the so-called marine ice sheet instability (MISI).Recent observations on accelerated grounding-line retreat and insights in modelling the West Antarctica ice sheet give evidence that MISI is already on its way. Moreover, similar topographic configurations are also observed in East Antarctica, particularly in Wilkes Land. We present an ensemble of simulations of the Antarctic ice sheet using the f.ETISh ice-sheet model to evaluate tipping points that trigger MISI by forcing the model with sub-shelf melt pulses of varying amplitude and duration. As uncertainties in ice-sheet models limit the ability to provide precise sea-level rise projections, we implement probabilistic methods to investigate the influence of several sources of uncertainty, such as basal conditions. From the uncertainty analysis, we identify confidence regions for grounded ice interpreted as regions of the Antarctic ice sheet that remain ice-covered for a given level of probability. Finally, we discuss for each Antarctic basin the total melt energy needed to reach tipping points leading to sustained MISI.

Published
2020

15. Early Warning from Space for a Few Key Tipping Points in Physical, Biological, and Social-Ecological Systems

Author

Chinwe Ifejika Speranza, Cédric Jamet, Annett Bartsch, Gaël Durand, Didier Swingedouw, Alessandra Conversi, and Grégory Beaugrand

Subjects
Greenland and Antarctic ice sheets, Earth observation, Forcing (recursion theory), 010504 meteorology & atmospheric sciences, Warning system, business.industry, Process (engineering), Computer science, Atlantic overturning circulation, Environmental resource management, 010502 geochemistry & geophysics, Ecological systems theory, Tipping point (climatology), Sbpolar gyre system, 01 natural sciences, Earth system science, Geophysics, 13. Climate action, Geochemistry and Petrology, Cryosphere, 14. Life underwater, business, 0105 earth and related environmental sciences
Abstract

In this review paper, we explore latest results concerning a few key tipping elements of the Earth system in the ocean, cryosphere, and land realms, namely the Atlantic overturning circulation and the subpolar gyre system, the marine ecosystems, the permafrost, the Greenland and Antarctic ice sheets, and in terrestrial resource use systems. All these different tipping elements share common characteristics related to their nonlinear nature. They can also interact with each other leading to synergies that can lead to cascading tipping points. Even if the probability of each tipping event is low, they can happen relatively rapidly, involve multiple variables, and have large societal impacts. Therefore, adaptation measures and management in general should extend their focus beyond slow and continuous changes, into abrupt, nonlinear, possibly cascading, high impact phenomena. Remote sensing observations are found to be decisive in the understanding and determination of early warning signals of many tipping elements. Nevertheless, considerable research still remains to properly incorporate these data in the current generation of coupled Earth system models. This is a key prerequisite to correctly develop robust decadal prediction systems that may help to assess the risk of crossing thresholds potentially crucial for society. The prediction of tipping points remains difficult, notably due to stochastic resonance, i.e. the interaction between natural variability and anthropogenic forcing, asking for large ensembles of predictions to correctly assess the risks. Furthermore, evaluating the proximity to crucial thresholds using process-based understanding of each system remains a key aspect to be developed for an improved assessment of such risks. This paper finally proposes a few research avenues concerning the use of remote sensing data and the need for combining different sources of data, and having long and precise-enough time series of the key variables needed to monitor Earth system tipping elements.

Published
2020

17. Seasonal assessment of metal trace element contamination by PCA in Seybouse wadi (Algeria)

Author

Soumeya Khaled-Khodja, Semia Cherif, and Gaël Durand

Subjects
inorganic chemicals, 0106 biological sciences, Cadmium, geography, geography.geographical_feature_category, Trace element, chemistry.chemical_element, Zinc, 010501 environmental sciences, Contamination, 01 natural sciences, Chromium, Mediterranean sea, chemistry, 010608 biotechnology, Environmental chemistry, Environmental science, Arsenic, Wadi, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

The seasonal assessment of trace metallic elements in Seybouse wadi waters and sediments is performed by principal component analysis (PCA). This wadi is the second of Algeria considering its length and vast basin, and opens into the coastline of Annaba in the Mediterranean Sea. Monitoring mineral micropollutants showed that waters are primarily contaminated by aluminum Al, selenium Se, zinc Zn, copper Cu, chromium Cr, lead Pb, cadmium Cd and arsenic As, whereas sediments are essentially soiled by arsenic As, chromium Cr and nickel Ni. PCA shows a clear relation between the season and the type of metallic contamination, and it also helps in understanding its origins.

Published
2018

18. Sensitivity of grounding line dynamics to the choice of the friction law

Author

Gaël Durand, Julien Brondex, Olivier Gagliardini, and Fabien Gillet-Chaulet

Subjects
010504 meteorology & atmospheric sciences, Sea level rise, Grounding line, Ice stream, Law, Time horizon, Slip (materials science), 010502 geochemistry & geophysics, 01 natural sciences, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

Basal slip accounts for a large part of the flow of ice streams draining ice from Antarctica and Greenland into the ocean. Therefore, an appropriate representation of basal slip in ice flow models is a prerequisite for accurate sea level rise projections. Various friction laws have been proposed to describe basal slip in models. Here, we compare the influence on grounding line (GL) dynamics of four friction laws: the traditional Weertman law and three effective pressure-dependent laws, namely the Schoof, Tsai and Budd laws. It turns out that, even when they are tuned to a common initial reference state, the Weertman, Budd and Schoof laws lead to thoroughly different steady-state positions, although the Schoof and Tsai laws lead to much the same result. In particular, under certain circumstances, it is possible to obtain a steady GL located on a reverse slope area using the Weertman law. Furthermore, the predicted transient evolution of the GL as well as the projected contributions to sea level rise over a 100-year time horizon vary significantly depending on the friction law. We conclude on the importance of choosing an appropriate law for reliable sea level rise projections and emphasise the need for a coupling between ice flow models and physically based subglacial hydrological models.

Published
2017

19. Progress in Numerical Modeling of Antarctic Ice-Sheet Dynamics

Author

Frank Pattyn, Sainan Sun, Lionel Favier, and Gaël Durand

Subjects
Drift ice, Atmospheric Science, Global and Planetary Change, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, Antarctic ice sheet, 010502 geochemistry & geophysics, 01 natural sciences, Ice-sheet model, Climatology, Sea ice thickness, Sea ice, Cryosphere, Ice sheet, Geology, 0105 earth and related environmental sciences
Abstract

Numerical modeling of the Antarctic ice sheet has gone through a paradigm shift over the last decade. While initially models focussed on long-time diffusive response to surface mass balance changes, processes occurring at the marine boundary of the ice sheet are progressively incorporated in newly developed state-of-the-art ice-sheet models. These models now exhibit fast, short-term volume changes, in line with current observations of mass loss. Coupling with ocean models is currently on its way and applied to key areas of the Antarctic ice sheet. New model intercomparisons have been launched, focusing on ice/ocean interaction (MISMIP+, MISOMIP) or ice-sheet model initialization and multi-ensemble projections (ISMIP6). Nevertheless, the inclusion of new processes pertaining to ice-shelf calving, evolution of basal friction, and other processes, also increase uncertainties in the contribution of the Antarctic ice sheet to future sea-level rise.

Published
2017

20. Ocean circulation and sea-ice thinning induced by melting ice shelves in the Amundsen Sea

Author

Pierre Mathiot, Pierre Dutrieux, Paul Spence, Nicolas C. Jourdain, Nacho Merino, Julien Le Sommer, Gaël Durand, and Gurvan Madec

Subjects
Drift ice, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010505 oceanography, Antarctic sea ice, Oceanography, Atmospheric sciences, 01 natural sciences, Arctic ice pack, Ice shelf, Geophysics, Sea ice growth processes, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Sea ice thickness, Earth and Planetary Sciences (miscellaneous), Melt pond, Sea ice, 14. Life underwater, Geology, 0105 earth and related environmental sciences
Abstract

A 1/12° ocean model configuration of the Amundsen Sea sector is developed to better understand the circulation induced by ice-shelf melt and the impacts on the surrounding ocean and sea ice. Eighteen sensitivity experiments to drag and heat exchange coefficients at the ice shelf/ocean interface are performed. The total melt rate simulated in each cavity is function of the thermal Stanton number, and for a given thermal Stanton number, melt is slightly higher for lower values of the drag coefficient. Sub-ice-shelf melt induces a thermohaline circulation that pumps warm circumpolar deep water into the cavity. The related volume flux into a cavity is 100–500 times stronger than the melt volume flux itself. Ice-shelf melt also induces a coastal barotropic current that contributes 45 ± 12% of the total simulated coastal transport. Due to the presence of warm circumpolar deep waters, the melt-induced inflow typically brings 4–20 times more heat into the cavities than the latent heat required for melt. For currently observed melt rates, approximately 6–31% of the heat that enters a cavity with melting potential is actually used to melt ice shelves. For increasing sub-ice-shelf melt rates, the transport in the cavity becomes stronger, and more heat is pumped from the deep layers to the upper part of the cavity then advected toward the ocean surface in front of the ice shelf. Therefore, more ice-shelf melt induces less sea-ice volume near the ice sheet margins.

Published
2017

21. Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3)

Author

Nacho Merino, Adrian Jenkins, Gaël Durand, Lionel Favier, Nicolas C. Jourdain, Olivier Gagliardini, Fabien Gillet-Chaulet, Pierre Mathiot, Laboratoire sols, solides, structures - risques [Grenoble] (3SR ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), United Kingdom Met Office [Exeter], and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Effects of global warming on oceans, lcsh:QE1-996.5, Antarctic ice sheet, F700, Glacier, F800, Forcing (mathematics), F600, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Ice shelf, Plume, lcsh:Geology, 13. Climate action, Ice sheet, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Sea level, Geology, 0105 earth and related environmental sciences
Abstract

Oceanic melting beneath ice shelves is the main driver of the current mass loss of the Antarctic ice sheet and is mostly parameterised in stand-alone ice-sheet modelling. Parameterisations are crude representations of reality, and their response to ocean warming has not been compared to 3-D ocean–ice-sheet coupled models. Here, we assess various melting parameterisations ranging from simple scalings with far-field thermal driving to emulators of box and plume models, using a new coupling framework combining the ocean model NEMO and the ice-sheet model Elmer/Ice. We define six idealised one-century scenarios for the far-field ocean ranging from cold to warm, and representative of potential futures for typical Antarctic ice shelves. The scenarios are used to constrain an idealised geometry of the Pine Island glacier representative of a relatively small cavity. Melt rates and sea-level contributions obtained with the parameterised stand-alone ice-sheet model are compared to the coupled model results. The plume parameterisations give good results for cold scenarios but fail and underestimate sea level contribution by tens of percent for warm(ing) scenarios, which may be improved by adapting its empirical scaling. The box parameterisation with five boxes compares fairly well to the coupled results for almost all scenarios, but further work is needed to grasp the correct number of boxes. For simple scalings, the comparison to the coupled framework shows that a quadratic as opposed to linear dependency on thermal forcing is required. In addition, the quadratic dependency is improved when melting depends on both local and non-local, i.e. averaged over the ice shelf, thermal forcing. The results of both the box and the two quadratic parameterisations fall within or close to the coupled model uncertainty. All parameterisations overestimate melting for thin ice shelves while underestimating melting in deep water near the grounding line. Further work is therefore needed to assess the validity of these melting parameteriations in more realistic set-ups.

Published
2019

22. Assessment of Sub-Shelf Melting Parameterisations Using theOcean-Ice Sheet Coupled Model NEMO(v3.6)-Elmer/Ice(v8.3)

Author

Lionel Favier, Nicolas C. Jourdain, Adrian Jenkins, Nacho Merino, Gaël Durand, Olivier Gagliardini, Fabien Gillet-Chaulet, and Pierre Mathiot

Subjects
Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

Oceanic melting beneath ice shelves is the main driver of the current mass loss of the Antarctic ice sheet, and is mostly parameterised in stand-alone ice-sheet modelling. Parameterisations are crude representations of reality, and their response to ocean warming has not been assessed in regard to 3D ocean-ice sheet coupled models. Here, we assess various melting parameterisations ranging from simple scalings with far-field thermal driving to emulators of box and plume models, using a new coupling framework combining the ocean model NEMO and the ice-sheet model Elmer/Ice. We define six idealised one-century scenarios for the far-field ocean ranging from cold to warm, and representative of potential futures for typical Antarctic ice shelves. The scenarios are used to constrain an idealised geometry of the Pine Island glacier representative of a relatively small cavity. Melt rates and sea-level contributions obtained with the parameterised stand-alone ice-sheet model are compared to the coupled model results. The plume parameterisation underestimates the contribution to sea level when forced by the warm(ing) scenarios. The box parameterisation compares fairly well to the coupled results in general and gives the best results using five boxes. For simple scalings, the comparison to the coupled framework shows that a quadratic dependency to thermal forcing is required, as opposed to linear. In addition, the quadratic dependency is improved when melting depends on both local and nonlocal, i.e. averaged over the ice shelf, thermal forcing. The results of both the box and the two quadratic parameterisations fall within or close to the coupled model uncertainty. Considering more robust sub-shelt melting parameterisations is key to decrease uncertainties on the Antarctic contribution to sea level rise. Comparing parameterisations to ocean/ice-sheet coupled simulations under various scenarios helps to assess them.

Published
2019

23. Revisiting Antarctic ice loss due to marine ice-cliff instability

Author

Tamsin L. Edwards, Catherine Ritz, Antony J. Payne, Mark A. Brandon, Nicholas R. Golledge, Gaël Durand, Isabel Nias, Neil R. Edwards, Andreas Wernecke, Philip B. Holden, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), EDGe, and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG)

Subjects
geography, Multidisciplinary, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Global warming, 010502 geochemistry & geophysics, 01 natural sciences, Instability, Ice shelf, 13. Climate action, Climatology, Greenhouse gas, Interglacial, Cliff, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Predictions for sea-level rise this century due to melt from Antarctica range from zero to more than one metre. The highest predictions are driven by the controversial marine ice-cliff instability (MICI) hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming. But MICI has not been observed in the modern era and it remains unclear whether it is required to reproduce sea-level variations in the geological past. Here we quantify ice-sheet modelling uncertainties for the original MICI study and show that the probability distributions are skewed towards lower values (under very high greenhouse gas concentrations, the most likely value is 45 centimetres). However, MICI is not required to reproduce sea-level changes due to Antarctic ice loss in the mid-Pliocene epoch, the last interglacial period or 1992–2017; without it we find that the projections agree with previous studies (all 95th percentiles are less than 43 centimetres). We conclude that previous interpretations of these MICI projections over-estimate sea-level rise this century; because the MICI hypothesis is not well constrained, confidence in projections with MICI would require a greater range of observationally constrained models of ice-shelf vulnerability and ice-cliff collapse. By better quantifying uncertainties for marine ice-cliff instability, future Antarctic ice loss is predicted to be much lower than previously estimated.

Published
2019

24. Urinary pesticide concentrations in French adults with low and high organic food consumption: results from the general population-based NutriNet-Santé

Author

Gwendolina Limon, Rodolphe Vidal, Serge Hercberg, Nathalie Druesne-Pecollo, Denis Lairon, Jean Pierre Cravedi, Emmanuelle Kesse-Guyot, Laurent Debrauwer, Bruno Taupier-Letage, Pilar Galan, Julia Baudry, Gaël Durand, Adéline Delcambre, Equipe 3: EREN- Equipe de Recherche en Epidémiologie Nutritionnelle (CRESS - U1153), Université Paris 13 (UP13)-Institut National de la Recherche Agronomique (INRA)-Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Centre de Recherche Épidémiologie et Statistique Sorbonne Paris Cité (CRESS (U1153 / UMR_A_1125 / UMR_S_1153)), Institut National de la Recherche Agronomique (INRA)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris Descartes - Paris 5 (UPD5)-Université Sorbonne Paris Cité (USPC)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de la Recherche Agronomique (INRA)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris Descartes - Paris 5 (UPD5)-Université Sorbonne Paris Cité (USPC)-Institut National de la Santé et de la Recherche Médicale (INSERM), Analyse de Xénobiotiques, Identification, Métabolisme (E20 Metatoul-AXIOM), ToxAlim (ToxAlim), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Ecole Nationale Vétérinaire de Toulouse (ENVT), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Ecole d'Ingénieurs de Purpan (INPT - EI Purpan), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Recherche Agronomique (INRA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Recherche Agronomique (INRA)-MetaToul-MetaboHUB, Génopole Toulouse Midi-Pyrénées [Auzeville] (GENOTOUL), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Ecole Nationale Vétérinaire de Toulouse (ENVT), Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Génopole Toulouse Midi-Pyrénées [Auzeville] (GENOTOUL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), LABOCEA Laboratoire [Plouzané, France], Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Recherche Agronomique (INRA), Institut Technique de l'Agriculture Biologique (ITAB), Hôpital Avicenne [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP), Centre recherche en CardioVasculaire et Nutrition = Center for CardioVascular and Nutrition research (C2VN), Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM), ANR-13-ALID-0001, ANR-13-ALID-0001,BioNutriNet,Consommation d'aliments issus de l'agriculture biologique: déterminants et motivation vis-à-vis de la durabilité, impact nutritionnel, économique, environnemental et toxicologique(2013), Université Paris 13 (UP13)-Institut National de la Recherche Agronomique (INRA)-Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Centre de Recherche Épidémiologie et Statistique Sorbonne Paris Cité (CRESS (U1153 / UMR_A_1125 / UMR_S_1153)), MetaToul AXIOM (E20), Institut National de la Recherche Agronomique (INRA)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Ecole Nationale Vétérinaire de Toulouse (ENVT), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Ecole d'Ingénieurs de Purpan (INP - PURPAN), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Recherche Agronomique (INRA)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-MetaboHUB-MetaToul, MetaboHUB-Génopole Toulouse Midi-Pyrénées [Auzeville] (GENOTOUL), Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-MetaboHUB-Génopole Toulouse Midi-Pyrénées [Auzeville] (GENOTOUL), Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de Toulouse (UT)-Université de Toulouse (UT), HESAM Université (HESAM)-HESAM Université (HESAM)-Centre de Recherche Épidémiologie et Statistique Sorbonne Paris Cité (CRESS (U1153 / UMR_A_1125 / UMR_S_1153)), Université Paris Diderot - Paris 7 (UPD7)-Université Sorbonne Paris Cité (USPC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de la Recherche Agronomique (INRA)-Université Paris Diderot - Paris 7 (UPD7)-Université Sorbonne Paris Cité (USPC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de la Recherche Agronomique (INRA), Université Fédérale Toulouse Midi-Pyrénées-Ecole d'Ingénieurs de Purpan (INPT - EI Purpan), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-MetaToul-MetaboHUB, Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Hôpital Avicenne, and Centre recherche en CardioVasculaire et Nutrition (C2VN)

Subjects
Adult, Male, Urinary system, Food consumption, Population based, 030501 epidemiology, Toxicology, 03 medical and health sciences, chemistry.chemical_compound, Organophosphorus Compounds, Tandem Mass Spectrometry, Vegetables, Humans, Medicine, Prospective Studies, 2. Zero hunger, Pyrethroid, business.industry, Dietary exposure, Organophosphate, Public Health, Environmental and Occupational Health, pesticides, Middle Aged, Pesticide, Pollution, dietary exposure, chemistry, Fruit, Propensity score matching, Female, Food, Organic, epidemiology, France, 0305 other medical science, business, [SDV.AEN]Life Sciences [q-bio]/Food and Nutrition, Chromatography, Liquid
Abstract

International audience; An organic diet may reduce dietary exposure to pesticides but findings based on observational data are scant. We aimed to compare urinary pesticide concentrations between “organic” and “conventional” consumers from the NutriNet-Santé study. Organic food consumption was determined using a self-reported food frequency questionnaire. Individuals with a proportion of organic food in the whole diet (in g/d) below 10% were defined as low organic food consumers and those whose proportion was above 50% as high organic food consumers. A propensity score matching procedure was then used to obtain two similar subsets of 150 participants, differing mostly by the organic valence of their diet. Urinary pesticide and metabolite concentrations (organophosphorus, pyrethroid, and azole compounds) were determined by UPLC-MS/MS, standardized with respect to creatinine. The molar sums of total diethylphosphates, dimethylphosphates, and dialkylphosphates were also computed. Differences in distributions across groups were tested using Wilcoxon signed-rank test for matched data. Mean age was 58.5 years and 70% of participants were women. Significantly lower urinary levels of diethylthiophosphate, dimethylthiophosphate, dialkylphosphates, and free 3-phenoxybenzoic acid were observed among organic consumers compared to conventional consumers. Our findings confirm that exposure to certain organophosphate and pyrethroïd pesticides in adults may be lowered by switching from conventional to organic foods. This is particularly of high interest among conventional fruit and vegetable consumers, as their exposure may be the highest.

Published
2019

25. The safety band of Antarctic ice shelves

Author

Johannes J. Fürst, Matthias Braun, Laure Tavard, Fabien Gillet-Chaulet, Melanie Rankl, Gaël Durand, Olivier Gagliardini, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), and Friedrich Alexander University [Erlangen-Nürnberg]

Subjects
Cryospheric science, Drift ice, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, Antarctic sea ice, Environmental Science (miscellaneous), 010502 geochemistry & geophysics, 01 natural sciences, Ice shelf, Oceanography, 13. Climate action, [SDE]Environmental Sciences, Sea ice, Cryosphere, 14. Life underwater, Ice divide, Ice sheet, Climate and Earth system modelling, Social Sciences (miscellaneous), Geology, 0105 earth and related environmental sciences
Abstract

International audience; The floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as ‘passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no ‘passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large ‘passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg8 will be unlikely to instantly produce much dynamic change.

Published
2016

27. Brief communication: Impact of mesh resolution for MISMIP and MISMIP3d experiments using Elmer/Ice

Author

Vincent Peyaud, Olivier Gagliardini, Julien Brondex, Fabien Gillet-Chaulet, Laure Tavard, and Gaël Durand

Subjects
lcsh:GE1-350, Physics, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Grounding line, Meteorology, lcsh:QE1-996.5, Resolution (electron density), Geometry, 010502 geochemistry & geophysics, 01 natural sciences, lcsh:Geology, Ice-sheet model, Discontinuity (linguistics), Sea level rise, 13. Climate action, Sensitivity (control systems), Ice sheet, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

The dynamical contribution of marine ice sheets to sea level rise is largely controlled by grounding line (GL) dynamics. Two marine ice sheet model intercomparison exercises, namely MISMIP and MISMIP3d, have been proposed to the community to test and compare the ability of models to capture the GL dynamics. Both exercises are known to present a discontinuity of the friction at the GL, which is believed to increase the model sensitivity to mesh resolution. Here, using Elmer/Ice, the only Stokes model which completed both intercomparisons, the sensitivity to the mesh resolution is studied from an extended MISMIP experiment in which the friction continuously decreases over a transition distance and equals zero at the GL. Using this MISMIP-like setup, it is shown that the sensitivity to the mesh resolution is not improved for a vanishing friction at the GL. For the original MISMIP experiment, i.e. for a discontinuous friction at the GL, we further show that the results are moreover very sensitive to the way the friction is interpolated in the close vicinity of the GL. In the light of these new insights, and thanks to increased computing resources, new results for the MISMIP3d experiments obtained for higher resolutions than previously published are made available for future comparisons as the Supplement.

Published
2018

28. Children's contrast sensitivity function in relation to organophosphate insecticide prenatal exposure in the mother-child PELAGIE cohort

Author

Chloé Cartier, Gwendolina Limon, Florence Rouget, Sylvaine Cordier, Charline Warembourg, Christine Monfort, Dave Saint-Amour, Cécile Chevrier, Gaël Durand, Institut de recherche, santé, environnement et travail ( Irset ), Université d'Angers ( UA ) -Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -École des Hautes Études en Santé Publique [EHESP] ( EHESP ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ) -Université des Antilles ( UA ), Département de Psychologie [Montréal, Québec, Canada], Université du Québec à Montréal (UQAM), Département de Pédiatrie [CHU Rennes], Centre Hospitalier Universitaire de Rennes, LABOCEA Laboratoire [Plouzané, France], Centre Hospitalier Universitaire Sainte-Justine [Montréal, Québec, Canada], Université de Montréal, Département d'Ophtalmologie [Montréal, Québec, Canada], Université de Montréal [Montréal], French National Research Agency [ANR-2010-PRSP-007], Fondation de France (FdF), Institut de recherche en santé, environnement et travail (Irset), Université d'Angers (UA)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Département de Pédiatrie [Rennes] = Paediatrics [Rennes], CHU Pontchaillou [Rennes], Université de Montréal (UdeM), ANR-10-PRSP-0007,PEPSY(2010), Université d'Angers (UA)-Université de Rennes (UR)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), and CHU Sainte Justine [Montréal]

Subjects
0301 basic medicine, Male, Pediatrics, Insecticides, Vision, [ SDV.TOX ] Life Sciences [q-bio]/Toxicology, Breastfeeding, [ SDV.MHEP.PED ] Life Sciences [q-bio]/Human health and pathology/Pediatrics, 010501 environmental sciences, Toxicology, 01 natural sciences, chemistry.chemical_compound, Pregnancy, Contrast (vision), Organophosphate insecticides, Child, Children, media_common, General Neuroscience, Organophosphate, Confounding, Cognition, [SDV.TOX]Life Sciences [q-bio]/Toxicology, Prenatal Exposure Delayed Effects, Cohort, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Female, France, Adult, medicine.medical_specialty, media_common.quotation_subject, Urinary system, Development, [ SDV.EE.SANT ] Life Sciences [q-bio]/Ecology, environment/Health, 03 medical and health sciences, Organophosphorus Compounds, medicine, Humans, Contrast sensitivity, 0105 earth and related environmental sciences, [SDV.EE.SANT]Life Sciences [q-bio]/Ecology, environment/Health, [SDV.MHEP.PED]Life Sciences [q-bio]/Human health and pathology/Pediatrics, business.industry, Environmental Exposure, medicine.disease, 030104 developmental biology, chemistry, [ SDV.NEU ] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], business, Follow-Up Studies
Abstract

International audience; Human exposure to organophosphate pesticides (OP) is widespread. Several studies suggest that OP prenatal exposure alters the development of cognitive and behavioural functions in children, but the effects of OP prenatal exposure on child sensory functions are largely unknown. The aim of the study was to evaluate the association between OP prenatal exposure and visual processing in school-aged children from the mother-child PELAGIE cohort (France). OP biomarkers of exposure were measured in maternal urine samples at the beginning of pregnancy. The Functional Acuity Contrast Test (FACT) was used to assess visual contrast sensitivity in 180 children at 6 years of age. Linear regression models were performed on all children, and separately for boys and girls, taking into account various potential confounders, including maternal education and breastfeeding. No associations were observed in the whole sample, while maternal OP urinary metabolite levels were associated with a decrease of FACT scores in boys. These findings indicate that OP prenatal exposure might impair visual processing later in life in boys only.

Published
2018

29. Impact of increasing antarctic glacial freshwater release on regional sea-ice cover in the Southern Ocean

Author

Gaël Durand, Hugues Goosse, Pierre Mathiot, Nacho Merino, Julien Le Sommer, Nicolas C. Jourdain, and UCL - SST/ELI/ELIC - Earth & Climate

Subjects
Atmospheric Science, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Sea ice, glacial freshwater, Forcing (mathematics), Antarctic sea ice, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, Oceanography, Spatial distribution, 01 natural sciences, Ice shelf, Iceberg, 13. Climate action, Computer Science (miscellaneous), Climate model, 14. Life underwater, Glacial period, Southern Ocean, Geology, 0105 earth and related environmental sciences
Abstract

The sensitivity of Antarctic sea-ice to increasing glacial freshwater release into the Southern Ocean is studied in a series of 31-year ocean/sea-ice/iceberg model simulations. Glaciological estimates of ice-shelf melting and iceberg calving are used to better constrain the spatial distribution and magnitude of freshwater forcing around Antarctica. Two scenarios of glacial freshwater forcing have been designed to account for a decadal perturbation in glacial freshwater release to the Southern Ocean. For the first time, this perturbation explicitly takes into consideration the spatial distribution of changes in the volume of Antarctic ice shelves, which is found to be a key component of changes in freshwater release. In addition, glacial freshwater-induced changes in sea ice are compared to typical changes induced by the decadal evolution of atmospheric states. Our results show that, in general, the increase in glacial freshwater release increases Antarctic sea ice extent. But the response is opposite in some regions like the coastal Amundsen Sea, implying that distinct physical mechanisms are involved in the response. We also show that changes in freshwater forcing may induce large changes in sea-ice thickness, explaining about one half of the total change due to the combination of atmospheric and freshwater changes. The regional contrasts in our results suggest a need for improving the representation of freshwater sources and their evolution in climate models.

Published
2018

30. The Greenland and Antarctic ice sheets under 1.5 °C global warming

Author

Gaël Durand, Michiel R. van den Broeke, Nicholas R. Golledge, Xavier Fettweis, Xylar Asay-Davis, Heiko Goelzer, Frank Pattyn, Lionel Favier, Luke D. Trusel, Alexander Robinson, Catherine Ritz, Peter Kuipers Munneke, Antony J. Payne, Jan T. M. Lenaerts, Helene Seroussi, Edward Hanna, Rob DeConto, Sophie Nowicki, Laboratoire de Glaciologie [Bruxelles], Université libre de Bruxelles (ULB), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Department of Geography [Sheffield], University of Sheffield [Sheffield], Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire sols, solides, structures - risques [Grenoble] (3SR ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Département de Géographie, Université de Liège, Institute for Marine and Atmospheric Research [Utrecht] (IMAU), Utrecht University [Utrecht], Laboratoire de mécanique des sols, structures et matériaux (MSSMat), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université Libre de Bruxelles [Bruxelles] (ULB), EDGe, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-CentraleSupélec, Sub Dynamics Meteorology, and Marine and Atmospheric Research

Subjects
010504 meteorology & atmospheric sciences, Drainage basin, Forcing (mathematics), Environmental Science (miscellaneous), 010502 geochemistry & geophysics, 01 natural sciences, F860 Climatology, medicine, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, ComputingMilieux_MISCELLANEOUS, Collapse (medical), 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Global warming, Lead (sea ice), Glaciologie, [SDU]Sciences of the Universe [physics], 13. Climate action, Climatology, Ice sheet, medicine.symptom, Surface mass, Geology, Social Sciences (miscellaneous)
Abstract

Even if anthropogenic warming were constrained to less than 2 °C above pre-industrial, the Greenland and Antarctic ice sheets will continue to lose mass this century, with rates similar to those observed over the past decade. However, nonlinear responses cannot be excluded, which may lead to larger rates of mass loss. Furthermore, large uncertainties in future projections still remain, pertaining to knowledge gaps in atmospheric (Greenland) and oceanic (Antarctica) forcing. On millennial timescales, both ice sheets have tipping points at or slightly above the 1.5–2.0 °C threshold; for Greenland, this may lead to irreversible mass loss due to the surface mass balance–elevation feedback, whereas for Antarctica, this could result in a collapse of major drainage basins due to ice-shelf weakening., SCOPUS: re.j, info:eu-repo/semantics/published

Published
2018

31. Ice‐Shelf Melt Response to Changing Winds and Glacier Dynamics in the Amundsen Sea Sector, Antarctica

Author

Marion Donat-Magnin, Hubert Gallée, Julien Le Sommer, Paul Spence, Gaël Durand, Nicolas C. Jourdain, Institut des Géosciences de l’Environnement (IGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), University of New South Wales [Sydney] (UNSW), and Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Continental shelf, Glacier, Forcing (mathematics), 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Ice shelf, Geophysics, Complex response, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Ekman transport, Submarine pipeline, 14. Life underwater, Ice sheet, Geology, 0105 earth and related environmental sciences
Abstract

International audience; It has been suggested that the coastal Southern Ocean subsurface may warm over the 21st century in response to strengthening and poleward shifting winds, with potential adverse effects on West Antarctic glaciers. However, using a 1/128 ocean regional model that includes ice-shelf cavities, we find a more complex response to changing winds in the Amundsen Sea. Simulated offshore subsurface waters get colder under strengthened and poleward shifted winds representative of the SAM projected trend. The buoyancy-driven circulation induced by ice-shelf melt transports this cold offshore anomaly onto the continental shelf, leading to cooling and decreased melt below 450 m. In the vicinity of ice-shelf fronts, Ekman pumping contributes to raise the isotherms in response to changing winds. This effect overwhelms the horizontal transport of colder offshore waters at intermediate depths (between 200 and 450 m), and therefore increases melt rates in the upper part of the ice-shelf cavities, which reinforces the buoyancydriven circulation and further contributes to raise the isotherms. Then, prescribing an extreme grounding line retreat projected for 2100, the total melt rates simulated underneath Thwaites and Pine Island are multiplied by 2.5. Such increase is explained by a larger ocean/ice interface exposed to CDW, which is then amplified by a stronger melt-induced circulation along the ice draft. Our main conclusions are that (1) outputs from ocean models that do not represent ice shelf cavities (e.g., CMIP5 models) should not be directly used to predict the thermal forcing of future ice shelf cavities; (2) coupled ocean/ice sheet models with a velocity-dependent melt formulation are needed for future projections of glaciers experiencing a significant grounding line retreat.

Published
2017

32. Reducing uncertainties in projections of Antarctic ice mass loss

Author

Gaël Durand, Frank Pattyn, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Université Libre de Bruxelles [Bruxelles] (ULB), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Université libre de Bruxelles (ULB)

Subjects
010504 meteorology & atmospheric sciences, Meteorology, 01 natural sciences, Standard deviation, 010305 fluids & plasmas, Physics::Geophysics, 0103 physical sciences, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Projection (set theory), lcsh:Environmental sciences, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, lcsh:GE1-350, geography, geography.geographical_feature_category, lcsh:QE1-996.5, Ensemble average, Glacier, lcsh:Geology, 13. Climate action, Climatology, A priori and a posteriori, Polar, Climate model, Ice sheet, Geology
Abstract

Climate model projections are often aggregated into multi-model averages of all models participating in an intercomparison project, such as the Coupled Model Intercomparison Project (CMIP). The "multi-model" approach provides a sensitivity test to the models' structural choices and implicitly assumes that multiple models provide additional and more reliable information than a single model, with higher confidence being placed on results that are common to an ensemble. A first initiative of the ice sheet modeling community, SeaRISE, provided such multi-model average projections of polar ice sheets' contribution to sea-level rise. The SeaRISE Antarctic numerical experiments aggregated results from all models devoid of a priori selection, based on the capacity of such models to represent key ice-dynamical processes. Here, using the experimental setup proposed in SeaRISE, we demonstrate that correctly representing grounding line dynamics is essential to infer future Antarctic mass change. We further illustrate the significant impact on the ensemble mean and deviation of adding one model with a known bias in its ability of modeling grounding line dynamics. We show that this biased model can hardly be identified from the ensemble only based on its estimation of volume change, as ad hoc and untrustworthy parametrizations can force any modeled grounding line to retreat. However, tools are available to test parts of the response of marine ice sheet models to perturbations of climatic and/or oceanic origin (MISMIP, MISMIP3d). Based on recent projections of Pine Island Glacier mass loss, we further show that excluding ice sheet models that do not pass the MISMIP benchmarks decreases the mean contribution and standard deviation of the multi-model ensemble projection by an order of magnitude for that particular drainage basin.

Published
2015

33. Modelling the impact of submarine frontal melting and ice mélange on glacier dynamics

Author

J. Krug, Jérôme Weiss, Gaël Durand, Olivier Gagliardini, Université Grenoble Alpes (UGA), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:GE1-350, Glacier ice accumulation, geography, Glacier terminus, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, lcsh:QE1-996.5, Accumulation zone, Glacier, 010502 geochemistry & geophysics, Glacier morphology, 01 natural sciences, lcsh:Geology, Glacier mass balance, Crevasse, 13. Climate action, [SDE]Environmental Sciences, Geomorphology, lcsh:Environmental sciences, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

Submarine melting of the calving face of tidewater glaciers and the mechanical back force applied by the ice mélange layer are two mechanisms generally proposed to explain seasonal variations at the calving front of tidewater glaciers. However, the way these processes affect the calving rate and glacier dynamics remains uncertain. In this study, we used a finite element-based model that solves the full Stokes equations to simulate the impact of these forcings on two-dimensional theoretical flow line glacier configurations. The model, which includes calving processes, suggests that frontal melting affects the position of the terminus only slightly (less than a few hundred metres) and does not affect the multiannual glacier mass balance at all. However, the ice mélange has a greater impact on the advance and retreat cycles of the glacier front (more than several kilometres) and its consequences for the mass balance are not completely negligible, stressing the need for better characterization of forcing properties. We also show that ice mélange forcing against the calving face can mechanically prevent crevasse propagation at sea level and hence prevent calving. Results also reveal different behaviours in grounded and floating glaciers: in the case of a floating extension, the strongest forcings can disrupt the glacier equilibrium by modifying its buttressing and ice flux at the grounding line.

Published
2015

35. Combining damage and fracture mechanics to model calving

Author

J. Krug, Olivier Gagliardini, Gaël Durand, and Jérôme Weiss

Subjects
010504 meteorology & atmospheric sciences, Ice calving, 010502 geochemistry & geophysics, 01 natural sciences, Physics::Geophysics, Position (vector), Geomorphology, Dynamic equilibrium, Physics::Atmospheric and Oceanic Physics, lcsh:Environmental sciences, Earth-Surface Processes, Water Science and Technology, 0105 earth and related environmental sciences, lcsh:GE1-350, geography, geography.geographical_feature_category, lcsh:QE1-996.5, Front (oceanography), Fracture mechanics, Glacier, Mechanics, Iceberg, lcsh:Geology, 13. Climate action, Polar, Astrophysics::Earth and Planetary Astrophysics, Geology
Abstract

Calving of icebergs is a major negative component of polar ice-sheet mass balance. Here we present a new calving model relying on both continuum damage mechanics and linear elastic fracture mechanics. This combination accounts for both the slow sub-critical surface crevassing and the rapid propagation of crevasses when calving occurs. First, damage to the ice occurs over long timescales and enhances the viscous flow of ice. Then brittle fractures propagate downward, at very short timescales, when the ice body is considered as an elastic medium. The model was calibrated on Helheim Glacier, Southeast Greenland, a well-monitored glacier with fast-flowing outlet. This made it possible to identify sets of model parameters to enable a consistent response of the model and to produce a dynamic equilibrium in agreement with the observed stable position of the Helheim ice front between 1930 and today.

Published
2014

36. A double continuum hydrological model for glacier applications

Author

B. de Fleurian, Peter Råback, Olivier Gagliardini, E. Le Meur, Douglas Mair, Thomas Zwinger, and Gaël Durand

Subjects
lcsh:GE1-350, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, lcsh:QE1-996.5, Glacier, STREAMS, 010502 geochemistry & geophysics, Glacier morphology, 01 natural sciences, Ice-sheet model, lcsh:Geology, 13. Climate action, Spatial ecology, Cryosphere, Ice sheet, Geomorphology, Geology, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

The flow of glaciers and ice streams is strongly influenced by the presence of water at the interface between ice and bed. In this paper, a hydrological model evaluating the subglacial water pressure is developed with the final aim of estimating the sliding velocities of glaciers. The global model fully couples the subglacial hydrology and the ice dynamics through a water-dependent friction law. The hydrological part of the model follows a double continuum approach which relies on the use of porous layers to compute water heads in inefficient and efficient drainage systems. This method has the advantage of a relatively low computational cost that would allow its application to large ice bodies such as Greenland or Antarctica ice streams. The hydrological model has been implemented in the finite element code Elmer/Ice, which simultaneously computes the ice flow. Herein, we present an application to the Haut Glacier d'Arolla for which we have a large number of observations, making it well suited to the purpose of validating both the hydrology and ice flow model components. The selection of hydrological, under-determined parameters from a wide range of values is guided by comparison of the model results with available glacier observations. Once this selection has been performed, the coupling between subglacial hydrology and ice dynamics is undertaken throughout a melt season. Results indicate that this new modelling approach for subglacial hydrology is able to reproduce the broad temporal and spatial patterns of the observed subglacial hydrological system. Furthermore, the coupling with the ice dynamics shows good agreement with the observed spring speed-up.

Published
2014

37. Why marine ice sheet model predictions may diverge in estimating future sea level rise

Author

Gaël Durand and Frank Pattyn

Subjects
Shearing (physics), 0303 health sciences, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Grounding line, Future sea level, Geophysics, System of linear equations, 01 natural sciences, Ice shelf, Physics::Geophysics, Ice-sheet model, 03 medical and health sciences, Sea level rise, 13. Climate action, Climatology, General Earth and Planetary Sciences, Ice sheet, Physics::Atmospheric and Oceanic Physics, Geology, 030304 developmental biology, 0105 earth and related environmental sciences
Abstract

[1] Despite major recent efforts, marine ice sheet models aiming at predicting future mass loss from ice sheets still suffer from uncertainties with respect to grounding line migration. A recent model intercomparison provided tools to test how models treat grounding line dynamics in a three-dimensional setting. Here we use these tools to address to what extent differences in mass loss occur according to the approximation to the Stokes equations, describing marine ice sheet flow, used. We find that models that neglect components of vertical shearing in the force budget wrongly estimate ice sheet mass loss by ±50% over century time scales when compared to models that solve the full Stokes system of equations. Models that only include horizontal stresses also misrepresent velocities and ice shelf geometry, suggesting that interactions between the grounded ice sheet and the ocean will also be modeled incorrectly. Based on these findings, we strongly advise the use of high-order models to compute reliable projections of ice sheet contribution to sea level rise.

Published
2013
Full Text
View/download PDF

38. Grounding-line migration in plan-view marine ice-sheet models: results of the ice2sea MISMIP3d intercomparison

Author

Martin Rückamp, Philippe Huybrechts, Moritz Hütten, Richard C. A. Hindmarsh, Eric Larour, Torsten Albrecht, Stephen Cornford, Laura Perichon, Guillaume Jouvet, David Pollard, Daniel Goldberg, Helene Seroussi, Thomas Zwinger, Olivier Gagliardini, Nina Wilkens, Daniel F. Martin, G. Hilmar Gudmundsson, Mathieu Morlighem, Lionel Favier, Gaël Durand, Johannes J. Fürst, David Docquier, Malte Thoma, Angelika Humbert, Frank Pattyn, Oleg Rybak, Anthony J. Payne, Thomas Kleiner, Earth System Sciences, Physical Geography, and Geography

Subjects
Ice sheet modeling, 010504 meteorology & atmospheric sciences, Meteorology, Antarctic ice sheet, Flow (psychology), spatial variation, Perturbation (astronomy), boundary layer, 010502 geochemistry & geophysics, 01 natural sciences, Stability (probability), Physical Sciences and Mathematics, computer simulation, Sensitivity (control systems), error analysis, 0105 earth and related environmental sciences, Earth-Surface Processes, Numerical analysis, Grounding line, Institut für Physik und Astronomie, modeling, prediction, Mechanics, ice sheet, Boundary layer, Drag, steady-state equilibrium, Geology, Interpolation
Abstract

Predictions of marine ice-sheet behaviour require models able to simulate grounding-line migration. We present results of an intercomparison experiment for plan-view marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no buttressing effects from lateral drag). Perturbation experiments specifying spatial variation in basal sliding parameters permitted the evolution of curved grounding lines, generating buttressing effects. The experiments showed regions of compression and extensional flow across the grounding line, thereby invalidating the boundary layer theory. Steady-state grounding-line positions were found to be dependent on the level of physical model approximation. Resolving grounding lines requires inclusion of membrane stresses, a sufficiently small grid size (

Published
2013
Full Text
View/download PDF

39. Assimilation of surface velocities acquired between 1996 and 2010 to constrain the form of the basal friction law under Pine Island Glacier

Author

Jeremie Mouginot, Cyrille Mosbeux, Catherine Ritz, Fabien Gillet-Chaulet, Frédérique Rémy, Gaël Durand, Olivier Gagliardini, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, ice flow modeling, Drainage basin, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Glacier, inverse modeling, Slip (materials science), 010502 geochemistry & geophysics, 01 natural sciences, Highly sensitive, subglacial conditions, Geophysics, [SDU]Sciences of the Universe [physics], Law, Exponent, General Earth and Planetary Sciences, Inverse method, Geology, 0105 earth and related environmental sciences
Abstract

International audience; In ice-sheet models, slip conditions at the base between the ice and the bed are parameterized by a friction law. The most common relation has two poorly constrained parameters, C and m. The basal slipperiness coefficient, C, depends on local unobserved quantities and is routinely inferred using inverse methods. While model results have shown that transient responses to external forcing are highly sensitive to the stress exponent m, no consensus value has emerged, with values commonly used ranging from 1 to ∞ depending on the slip processes. By assimilation of Pine Island Glacier surface velocities from 1996 to 2010, we show that observed accelerations are best reproduced with m≥5. We conclude that basal motion, in much of the fast flowing region, is governed by plastic deformation of the underlying sediments. This implies that the glacier bed in this area cannot deliver resistive stresses higher than today, making the drainage basin potentially more sensitive to dynamical perturbations than predicted with models using standard values m = 1 or 3.

Published
2016

40. Antarctic icebergs melt over the Southern Ocean: Climatology and impact on sea ice

Author

Pierre Mathiot, Julien Le Sommer, Jean Tournadre, Nacho Merino, Gurvan Madec, Nicolas C. Jourdain, Gaël Durand, Université Grenoble Alpes (UGA), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), National Oceanography Centre [Southampton] (NOC), University of Southampton, United Kingdom Met Office [Exeter], Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ANR-12-BS06-0018,SUMER,Observation et modélisation de l'Antarctique de l'est(2012), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636))

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Sea ice, Antarctic sea ice, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Computer Science (miscellaneous), Cryosphere, 14. Life underwater, Southern Ocean, Sea ice concentration, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Icebergs, Geotechnical Engineering and Engineering Geology, Arctic ice pack, Iceberg, Freshwater fluxes, Fast ice, 13. Climate action, Climatology, Sea ice thickness, [SDE]Environmental Sciences, Geology
Abstract

International audience; Recent increase in Antarctic freshwater release to the Southern Ocean is suggested to contribute to change in water masses and sea ice. However, climate models differ in their representation of the freshwater sources. Recent improvements in altimetry-based detection of small icebergs and in estimates of the mass loss of Antarctica may help better constrain the values of Antarctic freshwater releases. We propose a model-based seasonal climatology of iceberg melt over the Southern Ocean using state-of-the-art observed glaciological estimates of the Antarctic mass loss. An improved version of a Lagrangian iceberg model is coupled with a global, eddy-permitting ocean/sea ice model and compared to small icebergs observations. Iceberg melt increases sea ice cover, about 10% in annual mean sea ice volume, and decreases sea surface temperature over most of the Southern Ocean, but with distinctive regional patterns. Our results underline the importance of improving the representation of Antarctic freshwater sources. This can be achieved by forcing ocean/sea ice models with a climatological iceberg fresh-water flux.

Published
2016

41. A comparison of two Stokes ice sheet models applied to the Marine Ice Sheet Model Intercomparison Project for plan view models (MISMIP3d)

Author

Olivier Gagliardini, Tong Zhang, Gaël Durand, Julien Brondex, Wei Leng, Lili Ju, Stephen Price, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), and Université Grenoble Alpes (UGA)

Subjects
lcsh:GE1-350, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Meteorology, lcsh:QE1-996.5, Plan (archaeology), 01 natural sciences, 010101 applied mathematics, Ice-sheet model, lcsh:Geology, [SDU]Sciences of the Universe [physics], Climatology, Environmental science, 0101 mathematics, Ice sheet, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

We present a comparison of the numerics and simulation results for two "full" Stokes ice sheet models, FELIX-S (Leng et al. 2012) and Elmer/Ice (Gagliardini et al. 2013). The models are applied to the Marine Ice Sheet Model Intercomparison Project for plan view models (MISMIP3d). For the diagnostic experiment (P75D) the two models give similar results (

Published
2016

42. Organophosphate Insecticide Metabolites in Prenatal and Childhood Urine Samples and Intelligence Scores at 6 Years of Age: Results from the Mother-Child PELAGIE Cohort (France)

Author

Florence Rouget, Gaïd Le Maner-Idrissi, Agnès Lacroix, Gwendolina Limon, Gaël Durand, Christine Monfort, Dave Saint-Amour, Chloé Cartier, Charline Warembourg, Cécile Chevrier, Sylvaine Cordier, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Institut de recherche en santé, environnement et travail (Irset), Université d'Angers (UA)-Université de Rennes (UR)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Laboratoire de Psychologie Expérimentale (LPE), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Université de Rennes 2 (UR2), LABOCEA, Département de psychologie, Centre de recherche et département d'ophtalmologie, CHU Sainte Justine [Montréal], Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )-Institut National de la Santé et de la Recherche Médicale (INSERM)-École des Hautes Études en Santé Publique [EHESP] (EHESP)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université d'Angers (UA), Université de Rennes 2 (UR2), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Bretagne Sud (UBS)

Subjects
0301 basic medicine, Insecticides, medicine.medical_specialty, Health, Toxicology and Mutagenesis, [SDV]Life Sciences [q-bio], Intelligence, Population, Urine, 010501 environmental sciences, Bioinformatics, 01 natural sciences, 03 medical and health sciences, Cognition, Organophosphorus Compounds, Pregnancy, medicine, Humans, Longitudinal Studies, Child, education, 0105 earth and related environmental sciences, Wechsler Intelligence Scale for Children, 2. Zero hunger, education.field_of_study, Obstetrics, business.industry, 030111 toxicology, Public Health, Environmental and Occupational Health, Wechsler Adult Intelligence Scale, Environmental Exposure, Environmental exposure, medicine.disease, 3. Good health, Maternal Exposure, Prenatal Exposure Delayed Effects, Children's Health, Cohort, Gestation, Female, France, business
Abstract

Background: Several studies suggest that exposure to organophosphate insecticides (OP) during pregnancy impairs neurodevelopment in children. Objectives: We evaluated associations between biomarkers of prenatal and postnatal OP exposure and cognitive function of 6-year-olds in a French longitudinal birth cohort. Methods: In 2002–2006, the PELAGIE mother–child cohort enrolled pregnant women from Brittany. For a random subcohort, we measured nonspecific dialkylphosphate metabolites (DAP) of OP in one maternal urine sample, collected before 19 weeks’ gestation, and in one urine sample collected from their 6-year-old children. Six subtests of the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV) were administered when the children were 6 years of age to evaluate cognitive function (n = 231). Linear regression models controlling for factors including maternal intelligence and the Home Observation for Measurement of the Environment score were used. Results: WISC-IV scores were not significantly associated with prenatal or childhood total DAP metabolites. WISC verbal comprehension score was significantly higher in association with the highest maternal urinary concentrations of diethylphosphate (DE) metabolites (5.5; 95% CI: 0.8, 10.3 for > 13.2 nmol/L vs. < LOQ), whereas WISC working memory score was significantly lower in association with the highest urinary concentrations of DE metabolites at age 6 years (–3.6; 95% CI: –7.8, –0.6 for > 11.1 nmol/L vs. < LOD). Conclusion: We found no evidence that prenatal OP exposure adversely affected cognitive function in 6-year-olds, perhaps because of the population’s socioeconomic status, which was higher than in previous studies, though other causal and noncausal explanations are also possible. The negative association between WISC score and concurrent DE urinary concentrations requires replication by longitudinal studies investigating childhood OP exposure. Citation: Cartier C, Warembourg C, Le Maner-Idrissi G, Lacroix A, Rouget F, Monfort C, Limon G, Durand G, Saint-Amour D, Cordier S, Chevrier C. 2016. Organophosphate insecticide metabolites in prenatal and childhood urine samples and intelligence scores at 6 years of age: results from the mother–child PELAGIE cohort (France). Environ Health Perspect 124:674–680; http://dx.doi.org/10.1289/ehp.1409472

Published
2016

43. Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

Author

Richard C. A. Hindmarsh, Gaël Durand, Vincent Peyaud, Tamsin L. Edwards, Catherine Ritz, and Anthony J. Payne

Subjects
Cryospheric science, geography, Multidisciplinary, geography.geographical_feature_category, Meteorology, Oceans and Seas, Bedrock, Antarctic Regions, Antarctic ice sheet, Bayes Theorem, Observation, Models, Theoretical, Present day, Global Warming, Instability, Current (stream), Climatology, Calibration, Metre, Probability distribution, Ice Cover, Seawater, Climate-change impacts, Geology, Quantile
Abstract

Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI)1, a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence2, 3, 4 that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions5, 6, 7, 8, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging9: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive2, 3, 10 to generate large ensembles for uncertainty assessment, and lower-resolution model projections11 rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments9 (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

Published
2015

44. Enhancement factors for grounded ice and ice shelves inferred from an anisotropic ice-flow model

Author

Gaël Durand, Maurine Montagnat, Catherine Ritz, Olivier Gagliardini, Fabien Gillet-Chaulet, Ying Ma, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), EDGE, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)-Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), EDGe, ANR-07-VULN-0009,VULN,NEEM-FRANCE(2007), European Project: 226375,EC:FP7:ENV,FP7-ENV-2008-1,ICE2SEA(2009), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire de France (IUF), ANR-07-VULN-0009,NEEM,NEEM-FRANCE(2007), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire de France (IUF)

Subjects
010506 paleontology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, Isotropy, Geophysics, Pressure ridge, 01 natural sciences, Ice shelf, Physics::Geophysics, Glaciology, Sea ice growth processes, Geotechnical engineering, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Astrophysics::Earth and Planetary Astrophysics, Ice sheet, Anisotropy, Physics::Atmospheric and Oceanic Physics, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

Polar ice is known to be one of the most anisotropic natural materials. For a given fabric the polycrystal viscous response is strongly dependent on the actual state of stress and strain rate. Within an ice sheet, grounded-ice parts and ice shelves have completely different stress regimes, so one should expect completely different impacts of ice anisotropy on the flow. The aim of this work is to quantify, through the concept of enhancement factors, the influence of ice anisotropy on the flow of grounded ice and ice shelves. For this purpose, a full-Stokes anisotropic marine ice-sheet flowline model is used to compare isotropic and anisotropic diagnostic velocity fields on a fixed geometry. From these full-Stokes results, we propose a definition of enhancement factors for grounded ice and ice shelves, coherent with the asymptotic models used for these regions. We then estimate realistic values for the enhancement factors induced by ice anisotropy for grounded ice and ice shelves.

Published
2010
Full Text
View/download PDF

45. Full Stokes modeling of marine ice sheets: influence of the grid size

Author

Gaël Durand, Emmanuel Le Meur, Richard C. A. Hindmarsh, Olivier Gagliardini, Thomas Zwinger, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Scientific Computing Ltd (CSC), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), ANR-06-VULN-0016,DACOTA,Dynamique des glaciers côtiers et rôle sur le bilan de masse global de l'Antarctique zone atelier du glacier de l'Astrolabe, Terre Adélie(2006), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Meteorology, Perturbation (astronomy), Geometry, Monotonic function, 01 natural sciences, Instability, Standard deviation, Finite element method, Ice shelf, Glaciology, Position (vector), [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

Using the finite-element code Elmer, we show that the full Stokes modeling of the ice-sheet/ice-shelf transition we propose can give consistent predictions of grounding-line migration. Like other marine ice-sheet models our approach is highly sensitive to the chosen mesh resolution. However, with a grid size down to

Published
2009

46. Relation between neighbouring grains in the upper part of the NorthGRIP ice core — Implications for rotation recrystallization

Author

Asbjørn Persson, Gaël Durand, Anders Svensson, and Denis Samyn

Subjects
geography, Recrystallization (geology), geography.geographical_feature_category, Ice crystals, Isotropy, Geometry, Physics::Geophysics, Grain growth, Crystallography, Geophysics, Ice core, Space and Planetary Science, Geochemistry and Petrology, Distribution pattern, Earth and Planetary Sciences (miscellaneous), Crystallite, Ice sheet, Geology
Abstract

We propose a new method to investigate the relationships between neighbouring crystals and apply it to the textures measured along the upper 900 m of the NorthGRIP ice core. This method shows unexpected correlations between neighbours in the so-called normal grain growth regime, questioning the classical view on the onset of rotation recrystallization in ice-sheets. Moreover, the fractionation rate associated to the rotation recrystallization appears constant through time. Finally, grains with low-angle boundaries do not present a special distribution pattern of their c -axes. This suggests that rotation recrystallization is an isotropic process not affected by the direction of the macroscopic strain.

Published
2008

47. Experimental design for three interrelated Marine Ice-Sheet and Ocean Model Intercomparison Projects

Author

Gaël Durand, Rupert Gladstone, Frank Pattyn, Xylar Asay-Davis, Tore Hattermann, David M. Holland, Ben Galton-Fenzi, G. H. Gudmundsson, Stephen Cornford, Paul R. Holland, Denise Holland, Daniel F. Martin, Helene Seroussi, and Pierre Mathiot

Subjects
Coupled model intercomparison project, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Meteorology, Atmospheric Model Intercomparison Project, 010502 geochemistry & geophysics, 01 natural sciences, 13. Climate action, Climatology, 14. Life underwater, Ice sheet, Geology, 0105 earth and related environmental sciences
Abstract

Coupled ice sheet-ocean models capable of simulating moving grounding lines are just becoming available. Such models have a broad range of potential applications in studying the dynamics of marine ice sheets and tidewater glaciers, from process studies to future projections of ice mass loss and sea level rise. The Marine Ice Sheet-Ocean Model Intercomparison Project (MISOMIP) is a community effort aimed at designing and coordinating a series of model intercomparison projects (MIPs) for model evaluation in idealized setups, model verification based on observations, and future projections for key regions in the West Antarctic Ice Sheet (WAIS). Here we describe computational experiments constituting three interrelated MIPs for marine ice sheet models and regional ocean circulation models incorporating ice shelf cavities. These consist of ice sheet experiments under the Marine Ice Sheet MIP third phase (MISMIP+), ocean experiments under the ice shelf-ocean MIP second phase (ISOMIP+) and coupled ice sheet-ocean experiments under the MISOMIP first phase (MISOMIP1). All three MIPs use a shared domain with idealized bedrock topography and forcing, allowing the coupled simulations (MISOMIP1) to be compared directly to the individual component simulations (MISMIP+ and ISOMIP+). The experiments, which have qualitative similarities to Pine Island Glacier Ice Shelf and the adjacent region of the Amundsen Sea, are designed to explore the effects of changes in ocean conditions, specifically the temperature at depth, on basal melting and ice dynamics. In future work, differences between model results will form the basis for evaluation of the participating models.

Published
2015

48. Recent elevation and velocity changes of Astrolabe Glacier, Terre Adelie, Antarctica

Author

Denis Blumstein, Etienne Ducasse, Etienne Berthier, Emmanuel Le Meur, Gaël Durand, and Fabien Gillet-Chaulet

Subjects
geography, geography.geographical_feature_category, Elevation, Glacier, East antarctica, Astrolabe, Pleiades, Geodesy, Geomorphology
Abstract

SPOT and Pleiades images acquired since 2002 are used to describe velocity and elevation changes on Astrolabe Glacier, East Antarctica. Multi-temporal pairs of images are used to generate velocity fields by automatically tracking surfaces features. Stereo-pairs are used to create DEMs. Using three DEMs (2003, 2007 and 2013), we describe a surprising surface elevation increase since 2002, that reached a mean rate of 1.8 m/yr between 2003 and 2007. Conversely, the velocity fields did not reveal any major change in velocity so the origin of the strong increase in elevation remains non elucidated

Published
2015

49. On the substantial influence of the treatment of friction at the grounding line

Author

Gaël Durand, Vincent Peyaud, Julien Brondex, Olivier Gagliardini, Fabien Gillet-Chaulet, and Laure Tavard

Subjects
Grounding line, Geotechnical engineering, Geology
Abstract

The dynamical contribution of marine ice sheets to sea level rise is largely controlled by grounding line (GL) dynamics. Seroussi et al. (2014) emphasised the sensitivity of numerical ice flow model results to the practical implementation of the friction of the ice on its bed in the very close vicinity of the GL. Elmer/Ice is a reference finite element (FE) ice flow model used in recent marine ice sheet model intercomparison (MISMIP) exercises. In the model, the GL is defined as the nodes where the ice is in contact with the bedrock but belong to both grounded and floating elements. Inherently to the FE method, computing the contribution of the friction by element requires evaluating the friction at the integration points. In Elmer/Ice, this is done by interpolating the values of the friction parameter C prescribed at the nodes. In this brief communication, we discuss and compare three alternative ways to prescribe the friction at the GL: (i) C is prescribed and non null at the GL nodes, (ii) C is set to zero at the GL nodes, and (iii) C is discontinuous at the GL nodes (i.e. is prescribed and non null for grounded elements and otherwise null). So far, all published results using Elmer/Ice were obtained with the first method. Using the MISMIP3d diagnostic experiment, we first show that, although the change in the total force at the base is insignificant, the three methods lead to significantly different velocity fields. We then show that these methods also lead to different steady state GL positions and different transient behaviours. Such model sensitivity to the methods discussed here is certainly specific to the high friction prescribed in the MISMIP experiments and should be smaller in real setups where friction in the vicinity of the GL would be expected to be lower. Results obtained with the three methods are available as Supplement for future comparisons.

Published
2015

50. Assimilation of Antarctic velocity observations provides evidence for uncharted pinning points

Author

Jeremie Mouginot, Nacho Merino, Noel Gourmelen, Laure Tavard, Gaël Durand, Johannes J. Fürst, Olivier Gagliardini, Fabien Gillet-Chaulet, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut des Biomolécules Max Mousseron [Pôle Chimie Balard] (IBMM), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Department of Earth System Science [Irvine] (ESS), University of California [Irvine] (UCI), University of California-University of California, School of Geosciences [Edinburgh], University of Edinburgh, Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes (UGA), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
lcsh:GE1-350, Drift ice, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, lcsh:QE1-996.5, Antarctic ice sheet, Pressure ridge, 010502 geochemistry & geophysics, Geodesy, 01 natural sciences, Ice shelf, lcsh:Geology, Stamukha, 14. Life underwater, Ice divide, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Pinning points, Geomorphology, lcsh:Environmental sciences, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

In ice flow modelling, the use of control methods to assimilate the dynamic and geometric state of an ice body has become common practice. These methods have primarily focussed on inverting for one of the two least known properties in glaciology, namely the basal friction coefficient or the ice viscosity parameter. Here, we present an approach to infer both properties simultaneously for the whole of the Antarctic ice sheet. After the assimilation, the root-mean-square deviation between modelled and observed surface velocities attains 8.7 m a−1 for the entire domain, with a slightly higher value of 14.0 m a−1 for the ice shelves. An exception in terms of the velocity mismatch is the Thwaites Glacier Ice Shelf, where the RMS value is almost 70 m a−1. The reason is that the underlying Bedmap2 geometry ignores the presence of an ice rise, which exerts major control on the dynamics of the eastern part of the ice shelf. On these grounds, we suggest an approach to account for pinning points not included in Bedmap2 by locally allowing an optimisation of basal friction during the inversion. In this way, the velocity mismatch on the ice shelf of Thwaites Glacier is more than halved. A characteristic velocity mismatch pattern emerges for unaccounted pinning points close to the marine shelf front. This pattern is exploited to manually identify seven uncharted features around Antarctica that exert significant resistance to the shelf flow. Potential pinning points are detected on Fimbul, West, Shackleton, Nickerson and Venable ice shelves. As pinning points can provide substantial resistance to shelf flow, with considerable consequences if they became ungrounded in the future, the model community is in need of detailed bathymetry there. Our data assimilation points to some of these dynamically important features not present in Bedmap2 and implicitly quantifies their relevance.

Published
2015

Catalog

Books, media, physical & digital resources
See catalog results