CEREGE

Climate change: a threat to plankton

Monnier Leslie — Mon, 25 Nov 2024 14:16:48 +0000

A new international study, led by researchers from CNRS Terre & Univers, reveals that planktonic foraminifera, micro-organisms that are essential to the ocean carbon cycle, are in decline despite their migration to cooler waters. This discovery, published in Nature, highlights the urgent need to protect these sentinels of the climate in the face of global warming and ocean acidification.

Climate change is exerting increasing pressure on marine ecosystems, particularly affecting planktonic foraminifera, micro-organisms that are essential to the ocean carbon cycle.

A recent study, carried out by the CEREGE research centre in Aix-en-Provence (Aix-Marseille University, CNRS, IRD & INRAE), the Fondation pour la Recherche sur la Biodiversité (FRB) at the Centre de Synthèse et d'Analyse sur la Biodiversité (CESAB) in Montpellier, and the Max Planck Institute of Chemistry in Mainz (Germany), reveals that foraminiferal populations are declining at an unprecedented rate as a result of ocean warming and acidification. High levels of CO₂, responsible for the acidification of the waters, are complicating the formation of the shells of these single-celled organisms, threatening their survival. These climate sentinels migrate to cooler waters in an attempt to adapt, but the environmental changes are happening faster than they can adjust.

What are planktonic foraminifera?

Planktonic foraminifera are microscopic unicellular organisms found in all oceans. They have the ability to form calcium carbonate shells. Once fossilised, these well-preserved remains in marine sediments provide a valuable natural archive recording past environmental changes, enabling scientists to trace how these organisms have adapted to and survived varied climatic conditions over tens of millions of years.

The international team, made up of French, German, Dutch, Japanese and Spanish scientists, analysed almost 200,000 samples of foraminifera collected since 1910 in order to study their response to climate change. The study, recently published in the journal Natureshows that these species are migrating towards the poles, in search of cooler waters, at a rate of up to 10 kilometres per year. By examining vertical profiles, the researchers also found that some species are moving deeper into the ocean to escape warmer surface temperatures. Despite these movements, foraminifera populations have declined by 25 % over the last 80 years. Tropical species are the hardest hit, as the intense warming in these regions is probably disrupting their reproductive cycles, leading to a major decline.

Researchers estimate that by the end of the 21st century^e century, many species of planktonic foraminifera could face unprecedented environmental conditions, potentially exceeding their survival thresholds. This could lead to further extinctions in tropical regions, with consequent repercussions for marine ecosystems and carbon storage. The increase in CO₂ levels in the ocean limits the formation of calcium carbonate, an essential component in the construction of foraminifera shells. The reduced production of planktonic foraminifera shells could therefore reduce the amount of carbon trapped on the seabed. Nevertheless, some species could migrate to the polar regions in search of cooler waters that are favourable to their development.

Key questions remain as to how these species will adapt to extreme acidification and rapidly changing environments. This highlights the need for further research into their adaptation strategies and conservation efforts to protect marine ecosystems in the face of ongoing climate change.

This research was funded by the Fondation pour la Recherche sur la Biodiversité (FRB) within the Centre de Synthèse et d'Analyse sur la Biodiversité (CESAB) and co-financed by the Max Planck Institute for Chemistry (MPIC) in Mainz, Germany, the CNRS-INSU LEFE programme and the Aix-Marseille University Initiative of Excellence - A*MIDEX.

Contacts

For more information

Chaabane, S., de Garidel-Thoron, T., Meilland, J. et al, Migrating is not enough for modern planktonic Foraminifera in a changing ocean. Nature (2024) DOI

Climate change: a proven threat to calcifying plankton, CNRS INSU, 22 Nov. 2024

Plankton are the backbone of the ocean - and may struggle with what's coming, The Washington Post, 13 Nov. 2024

50th anniversary of the discovery of Lucy - by Raymonde Bonnefille

Monnier Leslie — Fri, 01 Nov 2024 13:37:46 +0000

2024 celebrates the fiftieth anniversary of the discovery of Lucy (24/11/1974), the name given to the now-famous hominid skeleton discovered in Hadar, in the Afar region of Ethiopia.

This discovery paved the way for a wealth of research and field surveys that continue to enrich our knowledge of the evolution of our ancestors. Since then, considerable progress has been made, with new fossil remains belonging to several hominin species (including Australopithecines) having been found in the Ethiopian Rift.

Between 1966 and 1973, a fossil deposit in southern Ethiopia, in the lower Omo valley near the Kenyan border, was prospected by international multidisciplinary teams. Yves Coppens is leading the major French palaeontological expedition there, in conjunction with two British and American expeditions. Scattered fossil remains of hominids were found, including teeth, bone fragments and skulls (in East Turkana). They indicate the presence of Australopithecines in the northern tropical hemisphere from 2.5 Ma. Yves Coppens successfully publicised the Omo expedition. At the dawn of a brilliant career that began at the Musée de l'Homme in Paris, he was already famous when the first hominins were discovered in Afar, and his talent as a lecturer, communicator and author made "Lucy" a veritable myth of the origin of Humanity.

Maurice had discovered major sedimentary deposits in the lower Awash valley and needed to know their age in order to draw up a geographical and geological map for his thesis. From 1971 onwards, Maurice Taieb and Jon Kalb travelled and prospected together the immense territory of the nomads in virtually unknown regions. They discovered the extent of the sedimentary outcrops of the Rift and numerous fossil and carved tool deposits.

In 1971, Maurice Taieb brought back an elephant jawbone recognised by the palaeontologist Yves Coppens as belonging to a species, Elephas reckicharacteristic of the oldest strata in the Omo Valley palaeontological deposit, which was the subject of the first K/Ar dating.

In May 1972, Maurice invited Yves Coppens and Donald Johanson on a short tour, during which they reached Hadar. The abundance of fossil animal bones of all kinds, spread over an immense area, was breathtaking. On their return to the capital Addis Ababa, they set up the IARE (International Afar Research Expedition), which included Raymonde Bonnefille and Jon Kalb.

The first expedition to Hadar took place in autumn 1973. Motivated by the desire to find something, by the fascination of the unknown, and by a respectful understanding of each other's talents, the expedition of four doctoral students forged ahead, enthusiastic despite the difficulties. In December 1973, Donald Johanson located the bones corresponding to the knee joint of a standing Australopithecus.

From this first discovery, the scientific interest, quickly understood in the United States, and the numerous conferences enabled Donald Johanson to obtain substantial funding to continue prospecting.

In 1974, other American geologists and French prehistorians and palaeontologists joined the team. It had more equipment at its disposal, including Ethiopians from the Addis Ababa Museum. Donald Johanson and Tom Gray located the various parts of Lucy's skeleton, scattered on the surface, on the slope of a hill at locality 288. Maurice Taieb then enlisted the help of other geologists to establish Lucy's age at 3.2 Ma... and support his thesis!

This was followed by two fruitful years during which Maurice directed and organised the camps. Prospecting came to a halt in 1978, following the political and administrative changes that took place in Ethiopia with the end of the imperial regime. They were resumed in 1990, exclusively by the Americans, led by Donald Johanson, then B. Kimbel, supported and funded by the Institute of Human Origins.

They continue to this day, supplemented in neighbouring regions by those undertaken by other American and Ethiopian researchers. For half a century, the many discoveries in the Ethiopian Rift Valley have been a tribute to Maurice Taieb, the pioneer and discoverer of this Eldorado of archaeological and anthropological research.

Raymonde Bonnefille is a palaeopalynologist and CNRS research director emeritus.

Maurice Taieb, CNRS researcher and field geologist at the Quaternary Geology Laboratorywhich was later integrated into the CEREGEwas the first to discover the fossiliferous deposits of the lower Awash valley in Ethiopia.

Bold and daring, he ventured into the Afar region for his thesis in the 1970s in search of larger, older deposits.

Maurice travelled through difficult regions, with a remarkable sense of spatial awareness. He knows how to live in spartan conditions and make friendly contact with desert nomads like no one else. It was an Afar shepherd who pointed out the area where he had seen bones.

Bibliography

Taieb M. 1985 : " On the Land of the First Men "When geology becomes an adventure. Paris Robert Laffont.

Bonnefille R. 2018 : " In the footsteps of Lucy "Expeditions to Ethiopia. Paris. Odile Jacob.

Note by Raymonde Bonnefille, DR CNRS, young researchers

"By retracing this history, which for some is mythical, I hope that it will be a source of inspiration. Young researchers can always discover new things. That's the great thing about our job at the CNRS. In the geological field, following in Maurice's footsteps, there are still some unknowns to elucidate, which may be less publicised but are just as interesting. Prospecting The palaeoanthropological studies concern geographically limited territories and are not placed in the more general geological context of the temporal evolution of the Rift over the last 10 million years. We do not have an overall view as initially envisaged by M. Taieb and J. Kalb. For example, with all the volcanic ash dating now obtained, there is no geological map of the distribution of deposits over the entire Rift. At what altitude was it at the time of occupation by the first australopithecines? How did the succession of sedimentary deposits take place, with a single initial lake, later fragmented into several lakes moving from south to north? What was the respective role of tectonic movements and climatic changes? Why and how did this region remain the favourite domain of Australopithecines between 4 and 3 million years ago? These are just some of the issues that could be addressed in future hominin surveys.
Good luck to future researchers.

When tree rings reveal the age of one of Kazakhstan's most beautiful natural gems

Monnier Leslie — Thu, 24 Oct 2024 08:12:10 +0000

Located in the Tien Shan mountain range, in the Kolsai National Park and classified as a biosphere reserve by UNESCO, Lake Kaindy offers a landscape that is as mysterious as it is spectacular, as it is populated by 'ghost' trees.

From its turquoise waters emerge the trunks of spruce trees (Picea schrenkiana) submerged when the lake was formed, which has always aroused the interest of scientists and the wonder of visitors.

Until now, researchers and the local population attributed the formation of the lake to the 1911 earthquake, which caused extensive damage and numerous landslides in the region.

However, a new study by researchers at IMBE and CEREGE has recently challenged this hypothesis, thanks to innovative research based on dendrochronology. This method makes it possible to go back in time by analysing tree rings and thus date past events.

By comparing the tree-ring series of dead trees submerged in the lake with those of living trees on the surrounding slopes, the researchers were able to date the formation of the lake shortly after the autumn of 1888, thereby identifying another culprit: the Chilik earthquake that shook the same region on 11 July 1889, 22 years before the generally accepted date.

With a magnitude of 8.2, this very large earthquake produced a cascading effect, destabilising a slope, causing a landslide, damming the river flowing through the valley and causing the trees to suddenly drown as the lake formed.

The study is not limited to revising the history of this emblematic landscape of Kazakhstan. It also confirms that Lake Kaindy lies in the epicentral zone of the 1889 earthquake and suggests that the surface ruptures described nearby are very probably linked to this event.

By combining dendrochronological analyses with palaeoseismological research, this innovative work has improved our knowledge of the seismic risks in this region, which has been hit by several earthquakes since the end of the 19th century. It has added to our knowledge of the region's natural heritage and contributed to efforts to preserve a unique, fragile and threatened environment.

With the Tien Shan mountain range still seismically active, the scenario highlighted at Lake Kaindy could be repeated, with a chain of natural hazards, but this time in heavily urbanised areas: such a cascading effect would then be likely to produce the greatest material and human losses.

Publication

Miramont, C., Rizza, M., Guibal, F. et al. Tree rings reveal the correlation between the Kaindy Lake submerged forest and the historical 1889 M 8.2 Chilik earthquake (Kazakhstan).
Nat Hazards (2024).

Link to this article

Contact

Magali RIZZA
Cécile MIRAMONT

Why the water in the Cosquer cave remains below sea level

Monnier Leslie — Wed, 23 Oct 2024 11:42:37 +0000

This article studies air circulation in the Cosquer cave (Marseille - France), a semi-drowned decorated cave where some of the engravings and paintings from the Upper Palaeolithic are temporarily saved from rising sea levels. By studying air pressure variations in this cave, we can calculate the volume of connected voids and the air renewal rate. In addition, we can estimate the air permeability of the karstic rock mass, a measurement that is rarely possible in situ, and explain why the water level remains below sea level.

The conservation of decorated caves is highly dependent on the flow of air in the karstic network and through the surrounding rock. Air flows are governed by the pressure gradient and influenced by the shape of the karstic conduits and the permeability of the carbonate rock mass.

The Cosquer cave is an Upper Palaeolithic painted cave, half-submerged in coastal karst, where preservation also depends on water levels connected to the sea.

Hydroclimatic data, such as air pressure, air temperature and water level inside and outside the cave, were measured over several years in order to identify the main processes governing variations in water level, air flow and air renewal. The data show unusual behaviour for a karst: the air pressure in the karst is almost always higher than atmospheric pressure.

As a result, the water level in the cave is below sea level. Daily variations in the tide allow us to estimate the volume of the cave above water level. Although the air in the cave is confined by the rock and seawater, there are also external air intakes during short pressurisation events linked to waves, which can produce and force air bubbles to flow along the open underwater fissures or karstic conduits inside the massif.

In addition, the effective permeability of carbonate rocks to air at the scale of the massif is deduced from the decrease in air pressure in the cave during the summer season by applying Darcy's law in a partially saturated environment.

Six years of data show that permeability varies from year to year and as a function of cumulative rainfall during spring and summer. The driest years are correlated with higher permeability, a more rapid decrease in air pressure in the cave and a more rapid rise in the water level.

In the future, in the context of climate change, a disruption in the permeability of the rock is therefore expected in caves close to the surface, which will have an impact on air flows in the decorated caves and could alter their fragile hydroclimatic stability.

Pellet, H., Arfib, B., Henry, P., Touron, S., and Gassier, G.: Mesoscale permeability variations estimated from natural airflows in the decorated Cosquer Cave (southeastern France), Hydrol. Earth Syst. Sci. 28, 4035-4057, https://doi.org/10.5194/hess-28-4035-2024, 2024.

A collaboration between theAix-Marseille Universityon historical monuments research laboratory (Ministry of Culture), the CNRS and the Direction Régionale des Affaires Culturelles.

Publications

. Hydrol. Earth Syst. Sci. 28, 4035-4057, 2024.

. Infuse, AMU Webzine

FOCUS Hugo PELLET

Contact

Hugo PELLET
Bruno ARFIB
Pierre HENRY
Stéphanie TOURON

Cap Corse: the mystery of the rings

Monnier Leslie — Tue, 22 Oct 2024 15:00:07 +0000

Off Cap Corse, at a depth of more than 100 metres, mysterious formations have been discovered: more than a thousand perfectly circular rings measuring up to 20 metres in diameter.

To shed light on this unprecedented phenomenon in the Mediterranean, the Gombessa team, led by Laurent Ballesta, is conducting an in-depth investigation in collaboration with a multidisciplinary team of scientists.

Using an underwater station, a submarine and numerous experiments, the Gombessa team is seeking to understand how these strange structures are formed and to reveal the exceptional biodiversity they harbour.

Follow the expedition led by Laurent Ballesta to a depth of more than 120 m off the Mediterranean coast and understand what is at stake.

The Cap Corse and Agriate Marine Park financed this mission and decided to take concrete action to protect these jewels of the Mediterranean.

Contacts

Jérôme GATTACECCA
Edouard Bard
Minoru Uehara

Nature, October 2024, cover by J. Gattacecca

Monnier Leslie — Tue, 22 Oct 2024 13:38:30 +0000

Rock family tree

The cover shows a cross-sectional view of the interior of a meteorite recovered from the Mackay Glacier icefields during the 2005 field season of the Antarctic Search for Meteorites. To date only some 6% of meteorite falls have been reliably connected to their source. In this week's issue, two papers by Michaël Marsset and colleagues and Miroslav Brož and co-workers redress that balance, suggesting a probable origin for the majority of meteorites found on Earth. The researchers focused on the two most common types of meteorite: H and L chondrites. They determined

Cover imageJérôme Gattacceca/CNRS/CEREGE

Contact

©Jérôme GATTACECCA
DR-Research Director CEREGE
TP-Earth and Planets

The fragile future of the cradles of civilisation in the Anthropocene

Monnier Leslie — Tue, 22 Oct 2024 13:01:56 +0000

In a review published in Nature Sustainability, an international group of scientists from Europe, the United States and Asia explore how river deltas have played a central role in the development of societies over the last 7,000 years.

From the rise of the first centres of power and city-states in Mesopotamia, the Nile delta and the Asian deltas, the study reveals how the natural growth of these deltas - fed by river sediments - accompanied human progress.

Deltas have fostered innovations in water management, subsidence control and erosion mitigation, creating a profound interdependence between human civilisation and these dynamic environments.

However, while deltas continue to support megacities and vast economic activities, they are under increasing pressure in the Anthropocene.

To ensure their sustainability, deltas must withstand the rise in sea level caused by global warming. However, human pressures and reduced sediment supply are making them increasingly vulnerable, posing a major threat to their survival.

The study outlines the critical challenges facing deltas, particularly in terms of governance, management and planning, and highlights the importance of new technologies and strategies to address these issues.

Despite the potential solutions, the authors stress that without climate stabilisation, it will be extremely difficult to preserve the deltas. In scenarios of extreme sea-level rise (up to or exceeding two metres in the next two centuries), deltas could gradually sink, making human life and economic activities in these regions unsustainable.

This article, entitled " Delta Sustainability from the Holocene to the Anthropocene and Envisioning the Future The report, entitled "A future of mass migration from flooded deltas to higher ground, potentially putting an end to the long relationship between humans and deltas", looks ahead to a future marked by mass migration from flooded deltas to higher ground, potentially putting an end to the long relationship between humans and deltas.

Ultimately, the world may have to adapt to living with partially or fully submerged deltas.

Edward Anthony1, Jaia Syvitski2, Florin Zăinescu1,3, Robert J. Nicholls4, Kim M. Cohen5, Nick Marriner6, Yoshiki Saito7, John Day8, Philip S.J. Minderhoud9,10,11, Alessandro Amorosi12, Zhongyuan Chen13, Christophe Morhange1,14, Toru Tamura15,16, Alfred Vespremeanu-Stroe3, Manon Besset17, François Sabatier1, David Kaniewski18, Vittorio Maselli19

1*Aix Marseille University, CNRS, IRD, INRAE, Coll France, CEREGE, Aix-en-Provence, France.
2INSTAAR & Dept. Geol. Sci, University of Colorado, Boulder CO, 80309, USA.
3Faculty of Geography, University of Bucharest, Bucharest 010041, Romania.
4Tyndall Centre for Climate Change Research, University of East Anglia, Norwich, NR4 7TJ, UK.
5Utrecht University, PO Box 80125, 3508 TC Utrecht, The Netherlands.
6CNRS, ThéMA, Université de Franche-Comté, UMR 6049, MSHE Ledoux, 32 rue Mégevand, 25030 Besançon Cedex, France.
7Estuary Research Center, Shimane University of Matsue, 690-8504, Japan.
8Dept. of Oceanography & Coastal Sciences, College of the Coast & Environment, Louisiana State University, Baton Rouge LA, 70803, USA.
9Soil Geography and Landscape Group, Wageningen University, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands.
10University of Padova, Department of Civil, Environmental and Architectural Engineering (ICEA), Via Marzolo, 9 - 35131 Padova, Italy.
11Department of Subsurface and Groundwater Systems, Deltares Research Institute, Daltonlaan 600, 3584 BK Utrecht, the Netherlands.
12Department of Biological, Geological, and Environmental Sciences, University of Bologna, Piazza di Porta S.Donato 1, Bologna, Italy.
13State Key Laoboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China.
14Ecole Pratique des Hautes Etudes,PSL-AOROC, Paris, France.
15Geological Survey of Japan, AIST, Tsukuba, Ibaraki 305-8567, Japan.
16Graduate School of Frontier Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan.
17i-Sea, Bordeaux Technowest, 25 rue Marcel Issartier, 33700 Mérignac, France.
18Centre de Recherche sur la Biodiversité et l'Environnement (CRBE), Université de Toulouse, CNRS, IRD, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UT3), Toulouse, France

Publication

Delta sustainability from the Holocene to the Anthropocene and envisioning the future, Nature Sustainability, August 2024

INFUSE AMU, October 2024

Contact

. Edward ANTHONY
. François SABATIER

Tribute to Annie Vincens

Monnier Leslie — Mon, 21 Oct 2024 12:16:31 +0000

It was with great sadness that we learned of the death of Annie Vincens in Aix-en-Provence on 27 June 2024.

Annie Vincens was born in 1950 in Sanga Sanga, Indonesia. She worked as a researcher at the CNRS, first at the Laboratoire de Géologie du Quaternaire (LGQ) in Meudon-Bellevue from 1976, then in Marseille where she was appointed in 1984, and finally at the CEREGE in Aix-en-Provence.

Annie specialised in the study of environmental and climatic change in tropical Africa. At the start of her career, she became interested in the environment of the first humans, particularly in Kenya during the Pleistocene, on the initiative of R. Bonnefille, as part of international missions coordinated by G. Isaac and R.E.F. Leakey. Annie defended her doctoral thesis at the University of Aix-Marseille in 1982, entitled "Palynology, present-day and Plio-Pleistocene environments to the east of Lake Turkana (Kenya)". Before that, in 1977, she took part in palynological studies at the Lucy site in Ethiopia, as part of the International Afar Research Expedition led by Maurice Taieb.

Annie has been responsible for an impressive number of analyses of surface palynological samples in Kenya and Tanzania, and has taken part in work on the calibration between pollen rain, vegetation and climate, and in particular on modelling vegetation and climate through 'biomisation'. Annie has continued her work by analysing a number of more recent sites in East Africa (lakes Magadi, Natron, Rukwa and more recently Lake Masoko, an exceptional palynological series covering the last 40,000 years in Tanzania). Annie has also extended her expertise to the Congo Basin, where she took part in the ECOFIT programme, set up by M. Servant of ORSTOM (now IRD).

Finally, his exceptional expertise in pollen morphology and botany, as well as the rigour of his analyses, have made a major contribution to the African Pollen Data Bank (APD), in which she participated from the outset, and where she was responsible for standardising pollen nomenclature after verifying determinations using the reference collection of palynological slides at CEREGE and MNHN. Annie has trained many students, particularly from Africa, in palynology.

Annie's work will be remembered for the quality of the palynological analyses carried out, particularly on numerous boreholes in African lakes, data and articles whose scientific interest will remain for a long time to come.

Before retiring, Annie left all her data, carefully labelled, filed and classified. She did the same with the reference pollen collection, for which she reviewed all the slides and updated a file that not only gives the preservation status of each slide, but also updates the name of each specimen. This enormous amount of work is a testament to her dedication to the community and her relentless rigour.

Annie was passionate about botany. She published a booklet ("Le Plateau du Petit Arbois, Guide et détermination de 184 plantes par la couleur des fleurs"), illustrated with magnificent photos, listing the plant species of the Arbois plateau, near Aix-en-Provence, which she walked for years in search of ceps, chanterelles, bolets and even morels. For she was also an expert mycologist.

With a strong, uncompromising personality and undeniable intellectual honesty, Annie also wielded a caustic sense of humour that surprised and charmed at the same time. All those who worked with her had to get used to her verve of expression, which resonated throughout the LGQ and CEREGE premises. We all regretted her retirement, which deprived us of the jubilation of still hearing her speak her frank truths about Science, Research and Life...

We will remember his sincere and constant friendship.

Interdisciplinary field mission to Midelt

Monnier Leslie — Tue, 01 Oct 2024 09:40:20 +0000

Towards sustainable socio-environmental regeneration

The former mining province of Midelt in Morocco, affected by structural droughts, has been undergoing profound reorganisation for some forty years. Marked by the decline of industrial mining activities and the retreat of pastoralism, the reconversion is taking different directions: arboriculture, artisanal prospecting, mineral trading, urbanisation, etc. These forms of land use and occupation are accentuating socio-environmental tensions such as the dissemination of potentially polluting mining waste, the social insecurity of former miners and the redefinition of the agricultural sector around intensive monoculture.

The LMI AMIR has launched an interdisciplinary mission bringing together around thirty researchers in the social and environmental sciences to study socio-environmental changes in a post-industrial mining context affected by structural droughts.

Our ambition? To suggest ways of improving the situation for local people, in collaboration with local stakeholders.

Interdisciplinarity is at the heart of our approach to understanding and acting on the complexities of this dynamic region.

Contact

Clement Levard

Director of Research,

Sustainable Environment Team, CEREGE

Agri-Mine project (MITI-CNRS, 2024-2025)

History of climate since the year one conference

Monnier Leslie — Wed, 25 Sep 2024 09:38:22 +0000

Organised by Edouard Bard, Professor at the Collège de France, CEREGE Aix-en-Provence

History of the climate since the year one. A tribute to Emmanuel Le Roy Ladurie