New insights in the French Guiana continental shelf circulation and its relation to the North Brazil Current retroflection
Moored current measurements carried out from 6 October 2003 to 18 February 2004 over the French Guiana continental shelf are presented. Two contrasted situations have been evidenced in which the currents were either weak and oscillating during the first period ( from October to early December) or strong and northwestward during the rest of the survey. Further analysis of these measurements in light of Moderate Resolution Imaging Spectroradiometer satellite images have revealed that these situations are mainly due to the motion of an outer shelf mesoscale feature: the North Brazil Current (NBC) retroflection. Two other main results have also been evidenced in this survey: ( 1) When the NBC retroflection occurs northwestward of the French Guiana continental shelf, part of the NBC climbs over the shelf slope and propagates to the inner shelf, and ( 2) the "Guyana current'' does not persist throughout the year at a 22 m depth and below. Finally, the location of the NBC retroflection has also a strong impact on the spread of the Amazon plume over the French Guiana continental shelf and is felt to have an influence on the nutrient supply in this region.
(Journal of Geophysical Research. vol. 112, n° 0148-0227, 27/05/2026)
LOB, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR EME, IRD, IFREMER, UM, COM, INSU - CNRS, CNRS
H4 abrupt event and late Neanderthal presence in Iberia
Heinrich event 4 (H4) is well documented in the North Atlantic Ocean and the adjacent continents as a cooling event 39,000 yr before present (BP). To quantify the impact of this event with respect to climate and vegetation over the Iberian Peninsula, we perform numerical experiments using a high-resolution general circulation model forced by sea surface temperatures before and during H4. Our model simulates an expansion of aridity over the peninsula during H4, a desertification of the south, and a replacement of arboreal by herbaceous plants in the north, all of which are in agreement with contemporaneous pollen sequences from marine cores located off the Iberian Peninsula. Our simulations demonstrate that the H4 marine event imprinted drastic changes over Southern Iberia, which would not have favoured its occupation by Anatomically Modern Humans, therefore providing a plausible explanation for the delayed extinction of Neanderthals in this region inferred from the archaeological record.
(Earth and Planetary Science Letters. vol. 258, n° 0012-821X, pp. 283 à 292, 27/05/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, ArScAn, UP1, UP8, UPN, MCC, CNRS, LGGE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PACEA, UB, CNRS, GW
Low-latitude "dusty events" vs. high-latitude "icy Heinrich events
It has been proposed that tropical events could have participated in the triggering of the classic, high-latitude, iceberg-discharge Heinrich events (HE). We explore low-latitude Heinrich events equivalents at high resolution, in a piston core recovered from the tropical northwestern African margin. They are characterized by an increase of total dust, lacustrine diatoms and fibrous lacustrine clay minerals. Thus, low-latitude events clearly reflect severe aridity events that occurred over Africa at the Saharan latitudes, probably induced by southward shifts of the Inter Tropical Convergence Zone. At a first approximation, it seems that there is more likely synchronicity between the high-latitude Heinrich Events (HEs) and low-latitude events (LLE), rather than asynchronous behaviours.
(Quaternary Research. vol. 68, n° 0033-5894, pp. 379-386, 27/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PBDS, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France]
Actions de diffusion de la culture scientifique et d'incitations aux sciences
The CSNSM contributes to the popularization of knowledge through various actions such as conferences for teenagers and students, redaction of books or papers for the general public, web sites, answers to Frequently Asked Questions.
(27/05/2026)
CSNSM, UP11, IN2P3, CNRS, DRECAM, CEA, LPN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPNO, UP11, IN2P3, CNRS, IBCP, UCBL, CNRS, LHEEA, ECN, CNRS
About the potential role of dust aerosols on the meningitis disease in Western Africa”
(pp. xx, 27/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CRC, UB, CNRS
Chronology and climate forcing of the last four interglacials
The last four interglacials (intervals during which global ice volume was similar to, or less than, that of our current warm stage) correspond to the warmest parts of the marine oxygen isotope stages marine isotopic age (MIS) 5, 7, 9, and 11. These interglacials followed the 100-kyr rhythm of eccentricity, but each had different insolation regimes, different durations, different ice volumes, and different sea-level heights. However, atmospheric greenhouse gas concentrations were similar and reached values, which, largely, were close to those of the current interglacial (Holocene or MIS 1) before the industrial revolution led to the artificial enrichment of the atmosphere's greenhouse gas concentrations via the burning of fossil fuels. This chapter summarizes the state of knowledge on each of the climatic warm intervals.
(. vol. 7, pp. 597-614, 27/05/2026)
MPI-M, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UCLouvain, DESY, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, DISAT, UNIMI, MARUM, KU Leuven, TU Darmstadt, INSU - CNRS, CEP, UNIBE, JGU, DEPE-IPHC, IPHC, UNISTRA, Université de Haute-Alsace (UHA), IN2P3, CNRS
Holocene long- and short-term climate changes off Adélie Land, East Antarctica
Diatom data from a marine sediment core give insight on Holocene changes in sea-surface conditions and climate at high southern latitudes off Adélie Land, East Antarctica. The early to mid-Holocene was warmer than the late Holocene with a transition at ∼4000 calendar years B. P. Sea ice was less present and spring-summer growing season was greater during the warm period relative to the cold one, thus limiting sea ice diatom production and favoring more open ocean diatom to develop. The long-term Holocene climatic evolution in East Antarctica is explained by a combination of a delayed response to local seasonal insolation changes coupled to the long memory of the Southern Ocean. Abrupt variations of the diatom relative abundances, indicating rapid climate changes, are superimposed to the Holocene long-term trends. Spectral analyses calculate robust frequencies at ∼1600 a (where “a” is years), ∼1250 a, ∼1050 a, ∼570 a, ∼310 a, ∼230 a, ∼150–125 a, ∼110 a, ∼90 a, and ∼66 a. Such periods are very close to solar activity cyclicities, except for the periods at ∼310 a and ∼1250 a, which are close to internal climate variability cyclicities. Wavelet analyses estimate the same periods but indicate nonstationary cyclicities. Rapid climate changes at high southern latitudes may therefore be explained by a combination of external (solar) and internal (thermohaline circulation) forcings.
(Geochemistry, Geophysics, Geosystems. vol. 8, pp. 1 à 15 pages, 27/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGGE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, INSU - CNRS, CNRS, HNHP, MNHN, CNRS
Climate variability of the last five isotopic interglacials: Direct land-sea-ice correlation from the multiproxy analysis of North-Western Iberian margin deep-sea cores
(pp. 375-386 (chapter 25), 27/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Influence of the parasite worm Polydora sp. on the behaviour of the oyster Crassostrea gigas: a study of the respiratory impact and associated oxidative stress
The aim of this study was to investigate how the worm Polydora sp., which induces oysters into creating mud blisters in response to an irritation within their shells, could interfere with the oyster Crassostrea gigas physiology and ethology. The impact was characterized by studying two groups of oysters (non-parasitized and parasitized) during a 30 days period: (1) the animal behaviour by analysing their valve activity (valvometry), and (2) the animal respiratory physiology by measuring in vivo the oxygen partial pressure and the specific oxygen consumption in selected tissues (heart, fast and slow adductor muscle). We also researched a putative impact on the expression of several oxidative stress genes at the heart level. Our results show that Polydora sp. is clearly an oyster’s parasite as it induces a decrease in oyster growth according to the infestation intensity. Moreover, it modifies the behaviour and the respiratory physiology of the molluscs. Infested animals opened more frequently but for less time and their level of blood oxygenation was systematically higher than healthy molluscs. These high levels of oxygenation had no effect on the oxidative metabolism of the tissues studied but they induced oxidative stress. Indeed, the superoxide dismutase gene showed a threefold increase in expression in the heart of infested oysters. A putative scenario of the weakening mechanism is proposed.
(Marine Biology. vol. 152, n° 0025-3162, pp. 329-338, 27/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Holocene long- and short-term climate changes off Adélie Land, East Antarctica
Diatom data from a marine sediment core give insight on Holocene changes in sea‐surface conditions and climate at high southern latitudes off Adélie Land, East Antarctica. The early to mid‐Holocene was warmer than the late Holocene with a transition at ∼4000 calendar years B. P. Sea ice was less present and spring‐summer growing season was greater during the warm period relative to the cold one, thus limiting sea ice diatom production and favoring more open ocean diatom to develop. The long‐term Holocene climatic evolution in East Antarctica is explained by a combination of a delayed response to local seasonal insolation changes coupled to the long memory of the Southern Ocean. Abrupt variations of the diatom relative abundances, indicating rapid climate changes, are superimposed to the Holocene long‐term trends. Spectral analyses calculate robust frequencies at ∼1600 a (where “a” is years), ∼1250 a, ∼1050 a, ∼570 a, ∼310 a, ∼230 a, ∼150–125 a, ∼110 a, ∼90 a, and ∼66 a. Such periods are very close to solar activity cyclicities, except for the periods at ∼310 a and ∼1250 a, which are close to internal climate variability cyclicities. Wavelet analyses estimate the same periods but indicate nonstationary cyclicities. Rapid climate changes at high southern latitudes may therefore be explained by a combination of external (solar) and internal (thermohaline circulation) forcings.
(Geochemistry, Geophysics, Geosystems. vol. 8, pp. n/a-n/a, 27/05/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, PROMES, UPVD, CNRS