The Atlantic Meridional Overturning Circulation (AMOC) plays a key role on climate, by acting on the fluxes of heat, nutriments and salt all over the world. Most of the previous works have documented the production of the deep water from the North Atlantic ocean (North Atlantic Deep Water, NADW) since the Last Glacial Maximum (LGM), exhibiting a sluggish (during the LGM), and even a complete shut down (during the Younger Dryas YD or Heinrich 1 event H1) of the NADW production, associated to an increased contribution of the Southern-sourced water masses. However, the role of the intermediate water masses during these events still remain unclear. Indeed, contrasted results have emerged in the Atlantic ocean, with some areas showing an extension of the Antarctic Intermediate Water (AAIW) in all ocean basins, whereas there is no evidence of southern-sourced water masses in other areas. The reconstruction of the extension and contribution of the intermediate water masses is thus a key to better understand past changes in the relationships between the Atlantic and the Southern oceans, especially in relation with variations in the global Carbon cycle.

The objectives of the RIAD project are thus to reconstruct past changes in the source and ventilation of the intermediate water masses in the North-Eastern Atlantic ocean by applying a multi-proxy study to two marine sediment cores at intermediate water depth.

Key words : North-Eastern Atlantic ocean; intermediate water masses; Benthic foraminifera; Last Glacial Maximum (LGM); Stable isotopes (δ18O, δ13C) ; Elemental ratios (Mg/Ca, Sr/Ca, Li/Ca, Ba/Ca, Cd/Ca, U/Ca); Nd isotopes (εNd).

Mediterranean thermohaline circulation sensitivity : lessens from the past for future – MedSens


MedSens (2020-2023)

Project leader

K. Tachikawa (CEREGE, Aix-Marseille)

C. Colin (PI – GEOPS)


C. Colin (GEOPS), G. Siani (GEOPS), S. Sepulcre (GEOPS), F. Haurine (GEOPS), G. Wei (GEOPS), M. Revel (Géoazur, Nice), K. Tachikawa (CEREGE, Aix-Marseille), L. Vidal (CEREGE), T. de Garidel- Thoron (CEREGE), L. Beaufort (CEREGE), J.C. Dutay (LSCE), G. Ramstein (LSCE), L. Li (LMD).

The objective of MedSens project is to evaluate the Mediterranean Sea circulation sensitivity to hydrological/thermal perturbation under warm and strong seasonality condition which could be an analogue of future climatic conditions. To tackle this issue, we will combine (1) the reconstruction of Mediterranean Sea state during the past perturbation events of strong amplitude using a series of proxies including Nd isotopic compositions recorded in authigenic phases with (2) numerical simulation based on highly-resolved regional (1/8º) proxy-enabled models that can simulate localized convection in the Mediterranean Sea. Our target is organic-rich layers called sapropels that were deposited in stagnant circulation state, in particular sapropel S5 formed during the last interglacial period, the penultimate warm period comparable with near future. We will apply multi-proxy approach (geochemistry and micropaleontology, including new potential proxies) to a series of sediment cores along a large zonal transect in the Mediterranean Sea. The MedSens project is based on consortium of partners with complementary expertise: proxy reconstruction (CEREGE/GEOAZUR and GEOPS) and numerical modelling (LSCE/LMD).

Associated thesis

Amélie Plautre

Gao Guohui

« Exploring paleo-hydrology and its impact on sedimentary dynamic processes in the South China Sea » / MD 215



Project leader


Mission leaders

C. COLIN (GEOPS, France), Z. LIU (Tongji University, China) and A. Tien-Shun LIN (National Central University, Taiwan),

On-board scientific team

Thirty-five researchers and students from France (GEOPS, LSCE, IFREMER, and LOG laboratories), China (Key State Laboratory of Marine Geology, Tongji University) and Taiwan (Department of Earth Sciences du National Central University, National Sun Yat-sen University, Institute of Oceanography of the National Taiwan University).

Mission Hydrosed

The MD215 HYDROSED oceanographic campaign, conducted on board the Marion Dufresne, has allowed us to collect long marine sediment cores at sea water samples in the northern part of the South China Sea. The main scientific objective of the mission is to reconstruct the past hydrology of intermediate and deep water masses and also the climate of South East Asia and thus to estimate the impact on the dynamics of sediment transport to the ocean floor and earth-sea transfers.

The samples collected during the HYDROSED oceanographic campaign will allow us to:

1- Better constrain the origins and past variations of the intermediate and deep water masses in the northern part of the South China Sea and existing relationships with glacio-eustatic changes, the evolution of global thermohaline circulation (the Great Conveyor Belt) and regional climatic modifications;

2- Reconstruct past variability in the south-east Asian climate (the East Asian monsoon and the ENSO system) at a very high temporal resolution and to identify the potential impacts on deep sedimentation in the northern part of the South China Sea;

3- Reconstruct the past dynamics of sediment transfer from the continent (Taiwanese rivers) to the northern part of the South China Sea using a “source to sink” approach and to identify the climatic controls (paleo-typhoons, paleo-monsoons and changes in sea level);

4- Develop and/or improve geochemical tracers used for paleooceanographic reconstructions and increase our understanding of the distribution of neodymium isotopes *Nd) and concentrations of rare earth elements (REE) in a marginal sea that is greatly influenced by enormous discharges of freshwater and sediments from several Asiatic rivers.


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The objective of the Mingulay-Rockall mission (June 2016), conducted on board the Atalante, was to retrieve water samples and sediment cores in areas rich in deposits of deep coral with a view to using these records for paleooceanographic reconstructions.

The mission focused on two sample sites in particular:

1) The Mingulay site (in the Sea of Hebrides) characterized by the presence of cold water coral reefs (L. pertusa) which currently proliferate between depths of 100 and 150 m.

2) The Logachev site (SW of the Rockall Trough) also characterized by abundant coral colonies (L. pertusa and M. oculata) but at depths of about 750 m.

Mission Mingulay-Rockall

The project thus aims to conduct a multidisciplinary study based on these two sites (sedimentology, biology and geochemistry of corals) in order to reconstruct the growth history of these reefs as well as environmental changes (temperature, circulation of intermediate and sub-surface waters) over the course of the Holocene. We will this thus obtain reconstructions of the hydrology of the sub-surface and intermediate waters with unprecedented temporal resolutions at two sites located at different depths.

The project brings together research teams from Britain, Ireland and France and forms part of a national research effort which aims to study deep water coral ecosystems and to use fossil corals as natural archives that can provide high resolution reconstructions of past paleoclimatic changes (ANR HAMOC PI C. Colin).

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Monopol (Indian MONsOon PaleO-variabiLity) (2012-2016) & DIPOMOUSS (2019-2020)


ANR (2012-2016) / IFREMER (2019-2020)

Project leader

F. Bassinot (LSCE)

Partner Laboratories

GEOPS (Univ. Paris Saclay, campus Paris Sud Orsay)
CEREGE (CNRS-Univ. Aix-Marseille)
EPOC (CNRS – Univ. Bordeaux I)
IPGP (Univ. Paris-Diderot)
MNHN (Paris)
Tongji University (Shanghai)
China University of Geosciences (Pékin)
Peking University (Pékin)

The Indo-Asiatic monsoon is a major climatic phenomenon due to its economic and social impacts on one of the most densely populated regions of the world, and because of the scale of the heat and humidity transfers involved; in short, it is an essential element of the planet’s climate. The natural variability of the Indo-Asiatic monsoon, is however, not fully understood and its future evolution is difficult to model because of the complexity of the processes and the interactions involved (i.e. ocean dynamics, vegetation response, teleconnections with middle and high latitudes, monsoon/ENSO/IOD/ITF coupling).

The MONOPOL and DIPOMOUSS projects aim to study the water and sediments of the Tropical Indian Ocean (East and Central) in order to reconstruct the past variability of the Indo-Asiatic monsoon and its sensitivity to various types of forcing over the course of the Quaternary. They are based on the study of water samples and sedimentary cores taken in 2012 during the MONOPOL oceanographic expedition (on board the N/O Marion Dufresne II) and on further samples that will be taken in 2020 during the DIPOMOUSS campaign; the latter will employ rosettes, CASQ and CALYPSO corers and an interface (multi-tube) corer. The projects involve six laboratories – CEREGE, EPOC, GEOPS, IPGP, LSCE and MNHN- and are part of an international collaboration undertaken within the IGBP/PAGES – IMAGES programme (International Marine Global Changes Study).

Mission Monopol

Photograph of the Marion Dufresne taken during the MONOPOL oceanographic mission (Gulf of Bengal). Photo credit: Stéphanie Duchamp-Alphonse

In concrete terms, the paleooceanographic and paleoclimatic reconstructions are based on a multi-tracer approach which includes biological tracers (e.g. studies of calcareous nanofossil and pollen assemblages), sedimentary tracers and geochemical tracers (e.g. Ti/Al, δ18O, Mg/Ca). Past changes in alteration in the Himalayas linked to variations in the monsoon are identified on the basis of analysis of sedimentary tracers (clays, laser granulometry) and geochemical tracers (major and trace elements combined with Nd, Sr and Pb isotopes).
Our team focuses in particular on the Indian monsoon and its impact on the following dynamics: (i) Himalayan erosion and the transfer of sediments to the ocean as well as the distribution of Nd isotopes in the Bay of Bengal and their past evolution (the impact of erosion); (ii) Surface waters and thermocline/nutricline depth, which have a considerable impact on primary producers (particularly coccolithophores); and iii) the hydrology of subsurface and intermediate waters at the scale of glacial-interglacial cycles.

Mission Monopol

Photograph of the multi-corer used on board the Marion Dufresne, during the MONOPOL oceanographic mission: it allows samples to be taken from the water-sediment interface in the Gulf of Bengal. Photo credit: Stéphanie Duchamp-Alphonse


CHIli – COccolithes: The Regime of Westerlies and Oceanic Fronts in the South Pacific Ocean since the Last Glacial Maximum


INSU-LEFE-IMAGO 2013 (2013-2016)

Project leader

S. Duchamp-Alphonse (GEOPS)


L. Beaufort (CEREGE), G. Siani (GEOPS), E. Michel (LSCE), N. Durand (LMC14), et C. Kissel (LSCE).

Measurements of CO2 trapped in Antarctic ice reveal that the pCO2 of the atmosphere during the Last Glacial Maximum (LGM) was 80 to 110 ppmv lower than the pCO2 value recorded for the interglacial period, before any anthropic activity. It turns out that significant changes in the position and intensity of oceanic fronts and of winds from the west (westerlies) in the high latitudes of the Southern Hemisphere, could on their own explain these major changes in atmospheric pCO2   by impacting on (i) the physical pump (ventilation of intermediate and deep ocean water masses); (ii) the effectiveness of the biological pump (variations in primary production); and (iii) ice coverage. In other words, these three mechanisms impact significantly on the amplitude of CO2 exchanges between the ocean reservoir and the atmospheric reservoir. The objective of this project is to better define the impact of the ocean-atmosphere system of the southern high latitudes on global levels of pCO2 in the Last Glaciation by simultaneously considering the physical and biological pumps. In particular, it aims to tackle the following issues: (i) the impact of the regime of westerly winds and oceanic fronts on the ventilation of intermediate and deep ocean water masses in the South Pacific Ocean (water stratification v upwelling); and (ii) the effectiveness of the biological pump (variations in primary production) since the LGM through the study of coccolithic assemblages (calcareous phytoplankton) and measurement of COT and CaCO3 contents of three sedimentary cores taken from Sub Antarctic zone of the Pacific sector. Through a thesis being prepared by Elisabeth Teca (2019-2022), this project is completed by the study of diatom assemblages (siliceous phytoplankton) from sedimentary cores MD07-3088 and MD07-3082.

projet chicoFigure : Map showing the geographical locations of cores studied in this project (MD07-3100, MD07-3088 and MD07-3082); the cores follow a latitudinal transect within the sub Antarctic zone of the Pacific sector and are likely to record the dynamic of oceanic fronts in the region since the Last Glacial Maximum.

Associated thesis

Elisabeth Teca

Circulation InTeRmédiaire dans l’Océan iNdien depuis le dernier maximum GLACiairE


INSU-LEFE-IMAGO 2017 (2017-2019)

Project leader

S. Sepulcre (GEOPS


C. Colin (GEOPS), R. Ma (GEOPS), F. Bassinot (LSCE), N. Tisnérat-Laborde (LSCE), L. Licari (CEREGE)

The objectives of this research project fall within a study on the role of ocean circulation in the modalities of heat and salt transfer between low and high latitudes during the glacial-interglacial terminations. In particular, we are interested in changes that occurred between the Last Glacial Maximum and the Holocene at intermediate depths within the Bay of Bengal. In fact, while the role of intermediate water masses in the processes of teleconnection involved in the terminations is increasingly being studied for the Atlantic, Pacific and Southern Oceans, it remains little studied in the case of the Indian Ocean despite the presence of globally significant water masses. In order to meet our objectives, we propose a combined study of benthic foraminifera assemblages, which are sensitive to geochemical variations in water masses and sediment (trophic level, oxygen concentration), and geochemical tracers for a key period of the Earth’s climate history, Termination I: 1) Oxygen  (δ18O) and Carbon (δ13C) isotopic composition; 2) element ratios measured in tests of benthic foraminifera (Cd/Ca, Mg/Ca, B/Ca, Sr/Ca et U/Ca); 3) Δ14C (the difference between the C14 of planktonic and benthic  foraminifera); 4) εNd. These different complementary records, which are unprecedented for the study zone, allow us to accurately characterize variations in circulation at intermediate depths in the Bay of Bengal. These measurements will be compared to changes occurring at the surface and at depth both at the study site and at the scale of the Indian Ocean; ultimately, this will allow us to integrate these variations at a global scale. We will thus improve our understanding of the role of intermediate water masses during Termination I and the teleconnections between high latitudes and low latitudes.

projet citron-glace

Reconstruction of the extension of Antarctic Intermediate Waters a) at present and b) during the Last Deglaciation and its relationships to ventilation in the Southern Ocean and to CO2 degassing (Yu et al., EPSL, 2018.)

Associated thesis

Riufang Ma


Project leader

G. Siani (GEOPS) and Ricardo De Pol Holz (Centro de Investigación GAIA-Antárctica (CIGA) and Center for Climate and Resilience Research Universidad de Magallanes)

Other participants

S. Duchamp-Alphonse (GEOPS), E. Michel (LSCE), C. Kissel (LSCE), C. Latorre Hidalgo (Pontificia Universidad Católica de Chile).

Project / Programme

The impact of circulation changes and the melting of the Patagonian ice sheets on the regulation of atmospheric CO2 by the Southern Ocean.

This project is based on very close cooperation between three teams from the Nucleo Milenio Paleoclima Hemisferio Sur (NMPHS) at the Universidad de Magallenes and the Universidad Católica de Chile in Chile, and the GEOPS and LSCE labs in France.


The Southern Ocean (SO) and its circulation play a fundamental role in the global climate system. In fact, a key element of thermohaline circulation is the return route of water masses from the deep ocean to the surface via the dynamic of upwelling. This return route is in part controlled by latitudinal position and the intensity of westerly winds. In recent years, the study of the Southern Ocean and its upwellings has become a priority for a better understanding of the climate system since they control the quantities of heat and carbon transferred from the deepest ocean reservoir to the surface ocean and the atmosphere.

Beagle Channel(Isla Navarino)

Up until now, most studies have considered either the role played by the physical pump, or that played by the biological pump, to explain this transfer of carbon from the ocean to the atmosphere. However, the increase in upwelling in the Southern Ocean over the last glacial transition has led to an increase in exported biological production. It is, therefore, desirable to study the interactions between the two CO2 pumps by looking at high resolution climatic records sampled in key areas of the Southern ocean. The western part of South America and the adjacent South-East Pacific, are unique regions for answering key questions regarding the evolution of the world’s climate due to their transitional position between subtropical and subarctic climate regimes. This study region features important interactions between the various components of the climate system: large scale atmospheric circulation, Southern Ocean circulation, and CO2 exchange between the atmosphere and the ocean.


Beagle Channel (Isla Navarino)



Within the framework of the ECOS Sud-CONICYT cooperative programme, we propose a multi-tracer study of marine sedimentary cores from the South-East Pacific sector of the Southern Ocean. The last Glaciation and the transition to the Holocene are the most promising climate periods for studying the evolution of biological and physical CO2 pumps because they are characterized by major changes in global-scale ocean circulation. In particular, we aim to gain a better understanding of the impacts of the melting of the Patagonian ice sheets and ocean circulation on the regulation of atmospheric CO2 by the Southern Ocean. In addition, the high sedimentation rates of our climate archives will allow us to obtain high quality data with very robust temporal control.

Associated thesis

Margaux Brandon

Holocene North Atlantic Gyres and Mediterranean Overturning dynamic through Climate Changes


ANR (2013-2018)

Project leader

C. Colin

Partner Laboratories

GEOPS (Univ. Paris Saclay, campus Paris Sud Orsay)
Laboratoire des Sciences du Climat et de l’Environnement (LSCE/IPSL, CEA-CNRS-UVSQ)
EPOC-CNRS, Université de Bordeaux
CEREGE (CNRS-Univ. Aix-Marseille)
LPGNantes (Université de Nantes)
M2C (Université de Rouen)


The North Atlantic plays a fundamental role in the European climate through its system of meridional ocean circulation, known as Atlantic Meridional Overturning Circulation (AMOC) the dynamics of which control the salt and heat budgets of the North Atlantic. The intensity of the sub-polar gyre, which is in turn principally governed by atmospheric dynamics and flows of fresh water, today controls the northern limit of the intrusion of salty Mediterranean waters and the flows of sub-tropical Atlantic water reaching northern latitudes. Its dynamics also have a primary impact on the climate of Northern Europe. In this context, changes in the thermohaline circulation of the Mediterranean over the course of sapropel deposition events and exchanges of water masses between the eastern and western basins, on the one hand, and between the North Atlantic and the Mediterranean, on the other, still remain relatively unexplored and poorly quantified. Furthermore, the impact of hydrological changes occurring on the European edge of the Mediterranean is poorly constrained even though these Mediterranean waters can have an impact on the salt budgets and on the formation of deep water in the North Atlantic.



Our research aims to improve our knowledge of the hydrology of the Mediterranean and its European margin with a view to reconstructing the AMOC and thermohaline circulation in the Mediterranean during sapropel deposition events; we also aim to identify the impact that Mediterranean thermohaline circulation might have on circulation in the North Atlantic.

Associated missions

Mingulay-Rockall, Ice-CTD

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Associated thesis

Maxence Duhamel

MAGnesium thermometer Improvement for assessing Climate Sensitivity


INSU-LEFE-IMAGO 2016 (2016-2018)

Project leader

F. Bassinot (LSCE)


S. Sepulcre (GEOPS), X. Pang (LSCE/GEOPS), H. Dang (LSCE), D. Blamart (LSCE), T. de Garidel-Thoron (CEREGE)

One of the principal approaches used to gain a better understanding of climatic sensitivity involves comparing past changes in ocean temperature with variations in greenhouse gases (GHG) recorded in ice. This type of approach requires the compilation of a database of paleotemperature information covering key periods (e.g. the Last Glacial Maximum LGM) for which we have GHG data retrieved from ice cores. But recent compilation efforts have revealed a number of challenges: (i) the difficulty involved in combining estimations from different tracers, and (ii) a certain number of problems specific to each tracer. This is the case for ocean temperatures reconstructed on the basis of Mg/Ca ratios in foraminifera where three principal problems are encountered:

(i) Uncertainty regarding the taxonomy used by geochemists;

(ii) Heterogeneity of sample preparation protocols used combined with differences in the choice of calibrations;

(iii) The absence of a common strategy concerning the taking into account (or not) of salinity as a factor that might potentially affect the Mg/Ca signal.

In order the better constrain these difficulties, the MAGICS project adopts a three-pronged approach:

  1. The development of a strategy which allows the integration of Mg/Ca data from various labs (i.e. obtained using different analysis protocols) and the application of a temperature conversion which is as robust and coherent as possible;
  2. The creation of a new dataset, subject to taxonomic controls, which will allow us to draw conclusions regarding the potential impact of salinity on the Mg/Ca thermometer and to propose a method of correction;
  3. The more precise reconstruction of differences in ocean surface temperatures between the LGM and the present, with a particular focus on the intertropical band and the Pacific Warm Pool of the western pacific, and the use of this data to fine tune estimations of climatic sensitivity.

Projet magics

Map of ocean surface temperatures showing the connection between the Pacific and Indian Oceans and the extent of the present-day Warm Pool (Temperatures greater than 28°C).

Associated thesis

X. Pang