Past Ocean surface density from planktonic foraminifera calcite δ18O
Density of seawater is a critical property that controls ocean dynamics. Previous works suggest the use of the δ18O calcite of foraminifera as a potential proxy for paleodensity. However, potential quantitative reconstructions were limited to the tropical and subtropical surface ocean and without an explicit estimate of the uncertainty in calibration model parameters. We developed the use of the δ18Oc of planktonic foraminifera as a surface paleodensity proxy using Bayesian regression models calibrated to annual surface density. Predictive performance of the models improves when we account for inter-species specific differences. We investigate the additional uncertainties that could be introduced by potential evolution of the δ18Oc-density relationship with time – from the last glacial maximum (LGM) to the preindustrial (PI) – through the combination of past isotope enabled climate model simulations and a foraminiferal growth module. We demonstrate that additional uncertainties are weak globally, except for the Nordic Seas region. We applied our Bayesian regression model to LGM and Late Holocene (LH) δ18Oc foraminifera databases to reconstruct annual surface density during these periods. We observe stronger LGM density value changes at low latitudes compared to mid latitudes. These results will be used to evaluate numerical climate models in their ability to simulate ocean surface density during the extreme climatic period of the LGM. The new calibration has great potential to reconstruct the past temporal evolution of ocean surface density over the Quaternary. Under climates outside the Quaternary period and in ocean basins characterized by anti-estuary circulation, like the current Mediterranean Sea and Red Sea, our calibration could provide density estimates with larger uncertainty, a point that requires further investigations.
(Climate of the Past. vol. 22, n° 1814-9324, pp. 247-263, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICM, CSIC, CRM, UAB, AWI, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, VU, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Global biosphere productivity response to Atlantic Meridional Overturning Circulation collapse during Heinrich Stadial 4
The slowdown of the Atlantic Meridional Overturning Circulation (AMOC) due to ongoing climate change raises concerns about its impact on the global carbon cycle. Understanding how global biosphere productivity may respond to such changes is essential for predicting the future carbon cycle, yet quantifying past global biosphere productivity remains challenging. We use triple isotope composition of air oxygen ( 17 Δ) trapped in polar ice cores to reconstruct the global biosphere productivity over the period 40.5 to 38.6 thousand years before the present (ka B.P.), covering Heinrich Stadial 4, a period of weakened AMOC. Our data reveal a slight increase in productivity following a carbon dioxide (CO 2 ) rise around 39.5 ka B.P. Freshwater hosing experiments using a global climate model indicate that the CO 2 fertilization effect on the terrestrial biosphere offsets productivity decline caused by consequences of AMOC slowdown. Collectively, our results suggest that global biosphere productivity slightly increases in response to AMOC slowdown and accompanying changes.
(Science Advances. vol. 12, pp. eaea0455, 11/10/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, NBI, UCPH, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, MOSAIC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, MERMAID, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sinking Together? Settling Behavior of Microplastics in the Presence of Fine Sediments
Predicting microplastic (MP) transport in aquatic environments requires understanding how particle properties, hydrodynamics, and aggregation processes control vertical transport, particularly in turbid systems. Here we investigate how particle physical properties and interactions with fine sediments influence the settling velocity of small MPs (<125 μm) under controlled laboratory conditions. We propose a novel methodology using an optical settling column (SCAF) to measure the settling velocity of MPs with contrasting sizes, shapes, and densities, both as dispersed particles and in mixtures with fine cohesive sediments at concentrations typical of turbid environments, under three treatments: dispersed, preagitated, and prerested. Settling velocities of dispersed MPs were primarily governed by size and density with minor shape effects. Empirical models developed for natural particles accurately predicted the MP settling in this size range. In MPsediment mixtures, the settling behavior varied markedly with particle properties and treatment conditions. Irregular particles, particularly fragments, exhibited flocculation under all treatments and higher settling velocities, whereas larger spheres interacted weakly with sediments and settled independently. Under prerested conditions, most particles showed enhanced and more uniform settling, with floc velocities converging around ∼0.5-0.6 mm/s. These findings offer insights into aggregation-driven vertical transport and provide a basis for improving predictive models in turbid environments.
(Environmental Science and Technology. vol. 60, n° 0013-936X, pp. 10251-10262, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UAS, RHITME, Cerema, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Morphological Development and Evolution of Barchanoid Dunes on the Cap Ferret Coastal Spit
Barchans are crescent-shaped dunes with their convex side facing the wind and their horns pointing downwind, commonly observed in deserts but also in coastal environments. This study investigates the dune field of the Cap Ferret Spit (5-km wide, 23-km long; Atlantic Coast, SW France) including of series of barchanoids dunes, currently stabilized by forest cover. The aims are to classify each dune into distinct typologies and characterize their morphology in order to analyze their evolution. LiDAR-based analysis identified four distinct barchanoid dune types. Moreover, it revealed superimposed bedforms on the dunes, including draping and oscillating patterns, reflecting the influence of consistent wind regimes during dune development and migration. This study proposes an evolutionary sequence in which proto-barchans evolve into barchanoid ridges and eventually as mature isolated barchans. These findings provide insight into the geomorphological evolution of barchanoid dunes in a coastal context, and particularly their migration pattern on a coastal spit system
(. vol. 41, pp. 41 - 47, 11/10/2026)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Synthèse des résultats du questionnaire sur les pratiques de bancarisation des données issues des projets LEFE-CYBER
Cette enquête, menée dans le cadre du projet ANR SODIO, vise à dresser un état des lieux des pratiques de gestion, de bancarisation et de partage des données produites par les projets soutenus par l’action CYBER de l’AAP LEFE sur la période 2014–2025. Elle cherche également à identifier les principaux freins rencontrés par les porteurs de projets ainsi que leurs besoins en matière d’accompagnement. Une enquête par questionnaire a été menée auprès des porteurs de projets LEFE-CYBER. Après constitution et consolidation d’une base de 120 projets correspondant à 91 porteurs, 66 réponses ont été recueillies, soit un taux de participation de 73 %. Le questionnaire couvre différentes étapes du cycle de vie des données, de leur production à leur archivage et leur diffusion, et combine des questions quantitatives et qualitatives. Les résultats montrent que la production de données est systématique dans les projets étudiés, mais que leur bancarisation demeure limitée et hétérogène. Seuls 18 % des répondants déclarent avoir réalisé une bancarisation complète, tandis que 30 % indiquent une bancarisation partielle et 52 % n’avoir entrepris aucune démarche. L’enquête met également en évidence une connaissance encore inégale des dispositifs existants, notamment de la base LEFE-CYBER. Les principaux freins identifiés concernent le manque de temps, le besoin de soutien technique, la gestion de données complexes ou volumineuses et les difficultés liées au choix des entrepôts. Ces résultats soulignent l’importance de renforcer la sensibilisation, la formation et l’accompagnement des équipes de recherche, ainsi que d’intégrer la gestion et la bancarisation des données dès les premières phases des projets, dans une perspective de science ouverte.
(11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], OSU ECCE TERRA, ENS-PSL, PSL, INSU - CNRS, SU, CNRS
Antarctic sea ice over the past 130 000 years -Part 2: A review of its role in the Earth system
Antarctic sea-ice cover reached historically low levels in 2023, consistent with the simulated decline in sea-ice extent in response to anthropogenic warming. As Antarctic sea ice is closely linked to multiple components of the Earth system, its demise could precipitate widespread, cascading changes across the cryosphere, atmosphere, and ocean. However, the nature and strength of these interconnections remain poorly understood and are often inadequately represented in models. In this review, we combine modern observations, models, and paleoclimate archives spanning the last glacial cycle to examine how reductions in sea ice may affect other components of the Earth system. We review how Antarctic sea ice interacts with ocean and atmosphere circulation, ice sheets and ice shelves, marine productivity, and the carbon cycle. We find evidence from theory and models that Antarctic sea ice exerts important influences on the Earth system. Paleo-proxy reconstructions provide examples in which changes in sea ice co-occur with changes in the carbon cycle, marine productivity, and ocean circulation. However, isolating the specific impact of sea ice remains challenging in such a highly interconnected system.
(Climate of the Past. vol. 22, n° 1814-9324, pp. 1881-1911, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Late Holocene coastal sand-drift events and long-term socio-ecological resilience (Béniguet Island, Western France)
(Aeolian Research. vol. 76, n° 1875-9637, pp. 101048, 11/10/2026)
LETG - Brest, UBO EPE, UR2, CNRS, LETG, UBO EPE, UR2, CNRS, Nantes Univ - IGARUN, GR, UR, INSU - CNRS, CNRS, UBO EPE, CNRS, UP1, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Inrap
Determinants of residential pesticide contamination in vineyard regions: an indoor surface-based structural equation modeling approach
Background: Indoor contamination by agricultural pesticides and its determinants remain poorly characterized. Objective: This study investigates the influence of outdoor environmental factors, residential characteristics, and occupant behaviors on pesticide contamination inside homes. Methods: In 2020 and 2021, we collected surface wipe samples from 31 homes near vineyards during the peak pesticide spraying season, including dusty high surfaces (tops of doors, windows, shelves, furniture; n = 116), frequently touched surfaces (n = 272), and floors (n = 128). Eight fungicides were analyzed. Data on household characteristics and behaviors, home features and local environmental factors were gathered through questionnaires and databases. To capture some key processes of pesticide intrusion and removal, we developed specific scores from factors related to cleaning practices, air exchange, and track-in via residents and pets. We applied structural equation modeling to estimate both direct and indirect effects of potential determinants on indoor pesticide contamination for the three surface types. Three latent variables were included in the models: outdoor and indoor contamination, estimated through measured pesticide surface loadings, and household structure, estimated by socio-demographic data on occupants. Results were reported as standardized β coefficients. Results: Only two models achieved satisfactory fit levels (high surfaces and frequently touched surfaces). For high surfaces, pesticide contamination was significantly associated with local annual pesticide purchases (β = 0.48, p = 0.037), occupant track-in (β = 0.22, p = 0.033), and households with active adults and children (β = -0.48, p = 0.031), while air exchange in the room had no significant effect (β = -0.03, p = 0.74). For frequently touched surfaces, contamination was positively associated with local annual pesticide purchases (β = 0.79, p < 0.001), air exchange (β = 0.16, p = 0.02), and occupant track-in (β = 0.12, p = 0.06). In contrast, cleaning was negatively associated with contamination (β = -0.36, p < 0.001) while the presence of active adults and children was not (β = -0.11, p = 0.53). Significance: These findings refine our understanding of indoor pesticide contamination sources and can inform targeted interventions to reduce exposure among rural populations. Impact: Our research provides new insights into residential pesticide contamination in agricultural areas through an extensive collection of surface samples from homes near vineyards. Our results suggest a spatial and temporal gradient of indoor contamination. High surfaces may accumulate long-term pesticide residues, while floors could reflect more recent contamination. Frequently touched surfaces showed intermediate contamination. Outdoor-indoor transfers, driven by air exchange and track-in, appear to affect these surfaces differently. Frequent cleaning seems to help reduce contamination, and household characteristics may influence pesticide distribution. These findings may guide further research efforts to better understand contamination pathways and help refine future mitigation strategies.
(Journal of Exposure Science and Environmental Epidemiology, n° 1559-0631, 11/10/2026)
BPH, UB, INSERM, UB, Irset, UA, UR, EHESP, INSERM, Biosit : Biologie - Santé - Innovation Technologique, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOSYS, INRAE
Rôle de la variabilité spatio-temporelle de la couverture végétale sur la migration des cordons dunaires en Gironde
La détection et le suivi de la variabilité spatio-temporelle de la végétation dunaire sont déterminants afin de comprendre et anticiper les évolutions morphodynamiques des cordons dunaires. En comparaison avec d'autres régions européennes plus septentrionales, où la végétation dunaire est plus dense et dont les limites spatiales sont plus facilement identifiables, la végétation dunaire en Nouvelle-Aquitaine est plus éparse et sa détection et quantification représentent un défi scientifique. Une nouvelle méthode couplant l'imagerie satellitaire (Sentinel-2, 10 x 10 m) et l'utilisation d'un réseau de neurones (S2DR3) est présentée dans cette étude. Cette méthode permet d'obtenir une cartographie d'un indicateur de végétation (NDVI) à haute résolution spatiale (1 x 1 m) et de renouveler l'opération à une fréquence annuelle. L'évaluation des erreurs de géoréférencement (< 5 m) et de la cohérence spectrale des images satellite (0.73 < R < 0.86) a démontré la fiabilité de cette méthode, permettant d'analyser les variations spatio-temporelles de la végétation. Les résultats ont montré une diminution des valeurs de NDVI, de plus de moitié entre 2017 et 2024 avec de fortes disparités spatiales le long d'une section dunaire de 500 mètres située au nord de Carcans Plage (Gironde). En associant cette cartographie de la végétation avec des données topographiques (LiDAR aéroporté), des interactions entre la dynamique de végétation et les changements morphologiques ont pu être identifiées en mettant en évidence différents niveaux de couverture de végétation et de mobilité sédimentaire. Ces données offrent également de nouvelles perspectives, comme notamment leur intégration dans des modèles numériques morphodynamiques afin d'avoir une compréhension plus fine des interactions entre la végétation et la dynamique sédimentaire
(11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Reassessing Last Glacial Maximum Cooling With Proxy‐Constrained Emergent Relationships
Reconstructing global temperatures from sparse proxy data remains a key uncertainty in paleoclimate science. Here, we apply an emergent constraint framework that combines statistical relationships from paleoclimate model simulations with proxy‐based estimates to infer unknown climate variables. We compiled a new multiproxy data set of tropical land temperature reconstructions for the Last Glacial Maximum (LGM), which implies tropical terrestrial cooling of −4.2°C (−5.0 to −3.5°C, 95% Confidence Interval, CI). Applying our emergent constraint framework to this terrestrial temperature reconstruction, we derived updated estimates of tropical sea surface temperature (−2.6°C; −3.3 to −2.0°C, 95% CI) and global mean surface temperature (−5.4°C; −6.5 to −4.4°C, 95% CI). These observation‐based estimates support LGM cooling toward the colder end of published ranges, implying that very low equilibrium climate sensitivity (ECS < ∼3°C) is unlikely. Our method is adaptable for different time periods and climate variables, providing a flexible framework for integrating proxy and model information.
(Geophysical Research Letters. vol. 53, n° 0094-8276, pp. e2026GL123083, 11/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, MERMAID, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA