The life of a scholar is not without a few pleasant surprises. While studying the formation of hailstones in 1968, at a time when other projectiles (of an entirely different nature) hailed down on France’s streets, Jean Jouzel, then a young chemical engineer, had no idea that he would one day become a world renowned specialist in major climatic shifts based on his analysis of Antarctic and Greenland ice, nor that he would help raise public awareness of the potential impact of human activity on changes in the earth’s climate. “At that time, I only knew that I wanted to do research,” he recalled. “Since I was from Brittany, I decided to move to Paris where I was encouraged to do my dissertation on the formation of hailstones (which would later prove very useful…). Upon my arrival at CEA, in Saclay, where I started in a laboratory that Claude Lorius had frequented for about ten years, my first surprise was to learn that I was going to be working with glaciologists… I must confess that I had no idea what a glaciologist was at that time!”

The times have certainly changed for Jouzel, who, at the age of 55, claims to be first and foremost a geochemist, and who has honored his friend and mentor Claude Lorius with the epithet “the Adventurer.” Through his work to characterize the water isotopes deuterium and oxygen 18 (most notably the variation of their concentrations in the atmosphere, in precipitations and in the cryosphere), Jean Jouzel’s vibrant productivity has made him one of the most quoted authors in his field. The existence of a link between the isotopic contents of the ice and the temperature of the site is the key to climate reconstitution in the polar regions. “At each phase change of water, the condensed phase (in other words snow) is richer in heavy isotopes than the vapor phase that created it, a phenomenon that brings about a progressive reduction in the isotopic content of the vapor and the precipitation as the air mass cools,” he explained.

"By using simple isotopic models, I was able to demonstrate the importance of the role of kinetic fractionation when crystals of snow are formed by condensation. I was also interested in the development of more complex isotopic models based on the use of models of general atmospheric circulation as well as their application in correctly interpreting the isotopic measurements obtained in polar ice.”

Another “first” credited to Jean Jouzel and his team, was the elaboration of an indicator capable of providing information about the temperature and humidity prevalent in the oceanic regions where the precipitation was collected. “This indicator, which relies on the joint use of deuterium and oxygen 18 in the ice, also enabled us to prove the rather surprising existence of more than 200 meters of ice that had formed from the water of a sub-glacial lake at Vostok, in Antarctica.” About 10,000 km2 in size, the vast lake, 200 km in length and several hundred meters in depth, may harbor primordial microorganisms that are certain to rouse the curiosity of exobiologists. It is not surprising that the Russian outpost Vostok and its tiny speck of working-class humankind, perched at 3,500 meters in altitude in eastern Antarctica (which happens to be the highest point ever inhabited by man in these latitudes) has captured Jean Jouzel’s passions: “The different sediments (marine, continental or glacial) do provide us the means of reconstituting past variations in temperature; but only polar ice can reveal the composition of the atmosphere through an analysis of the tiny bubbles of air trapped in the ice,” he stressed. "This unique property, which we uncovered following the analysis of the Vostok ice cores taken during work conducted in conjunction with an international effort between France, the U.S. and Russia in the 1980s, enabled us to establish a firm link between the temperature and the concentration of green-house gases (methane and carbon dioxide) during successive glacial and interglacial periods. The data, which now cover four climatic cycles, or about 420,000 years, point toward a remarkable correlation between the climate and green-house gases throughout the entire period”. The systematic interpretation of the ice bore samples, which led to a flood of historic publications in the journal Nature, has also show that “the warming trend associated with glacial melting began in the Southern Hemisphere, that the rise in green-house gases preceded the melting of the large polar icecaps in the Northern Hemisphere, and that the Holocene (the period we now live in) has had the longest sustained period of stable climate.”

Although Jean Jouzel has been actively involved in international research projects drilling for ice core samples in Greenland (the European project GRIP – GReenland Ice core Project) and in Antarctica for the last 20 years, it is the EPICA project (European Project for Ice Coring in Antarctica) that his name is most closely associated with. “Encouraged by the success of GRIP in 1992, the European teams turned their attention to Antarctica in 1995. The idea was to undertake two deep drilling projects, one situated in the center of eastern Antarctica (Dome C), with the hope of covering five climatic cycles, and another in the Atlantic sector (Dronning Maud Land), to provide an optimal comparison with the data recorded in Greenland. Laboratories from ten different countries participated in the project. The project was supported by a dual sponsorship from the ESF (European Science Foundation) and the European Community, and in France, from the Institut Polaire Paul-Emile Victor (IPEV).” After supervising the project’s implementation and then taking over the presidency and general direction for seven years from 1995 to 2001, Jean Jouzel has now taken over as vice president. He is justifiably pleased with its success: “Despite the loss of a core drill at Dome C during the 1998-1999 drill operation, EPICA has been a total success! The drilling operation, which reached a depth of 2,871 meters, has already enabled us to reach ice that is estimated to be more than 500,000 years old. The second drilling operation has reached a depth of 450 meters. If all goes well, the two operations should be complete within two years.”

A devoted laboratory scientist, Jean Jouzel belongs to that community of scientists who are convinced – and concerned – by the extent of the potential problem posed by the rising concentrations of green-house gases associated with human activities and the urgent need to analyze all its facets. “The unanswered questions are legion,” he stressed. “Is global warming a reality, if so at what rate? What will the future climate be like? etc.” These questions led Jouzel to help play a part in the establishment of the Past Global changEs (PAGES) project in the middle of the 1980s (a component of IGBP, the International Geosphere-Biosphere Programme) devoted to changes in the past. Later, he became involved in the CLImate VARiability and predictability program (CLIVAR) in conjunction with the International Geosphere-Biosphere Programme and the PRMC. In 1995 and in 2001, he participated as a key author of the second and third reports of the International Panel on Climate Change (the IPCC was created in 1988 under the joint auspices of the United Nations Environment Programme and the World Meteorological Organization). Since the IPCC’s recent bureau leadership reshuffling in April 2002, Jean Jouzel has taken on a more institutional role within the organization as a member of IPCC’s bureau.

Acutely aware of the “extreme complexity” of “the thermal machine that is our planet, a system controlled by a large number of interactions between various reservoirs (the atmosphere, oceans, hydrosphere, biosphere, etc.) that have an impact over a very wide range of time scales (from one day to thousands of years) and spaces (from local and regional to a global scale)", Jean Jouzel nevertheless took pains to stress “the advances and discoveries that have been achieved” in his field over the last ten years, as well as “the contributions of paleo-data” to the debate on the evolution of the future climate: “an understanding of past climates will enable us to essentially situate current variations in a broader context,” Jouzel said. “This will also allow us to “tweak” the numerical models – elaborated to put the current climate into perspective and to better predict future variations – and verify they are capable of reproducing the past.” Regardless of the doubts that continue to cloud our climate’s future, Jean Jouzel is happy to have played a role in “breaking down the barriers that until recently have separated past climates from future climates. The scientific community has, on this point, done a real about-face. Now, everyone is convinced that it is increasingly imperative to better understand the past millennium’s climate to better anticipate future climatic changes.”

Born March 5, 1947 in Janzé (Ille-et-Vilaine), Jean Jouzel, has a teaching degree in chemistry (awarded in 1967), a maîtrise in physical chemistry (1968), a diploma from the Ecole supérieure de Chimie Industrielle in Lyon (1968), a D.E.A. in physical chemistry (1969), a doctorat in physical chemistry (his thesis, “Mesures du tritium dans de faibles quantités d’eau à la teneur naturelle”, was defended at the Faculté d’Orsay in 1973), and a doctorat-ès-sciences (his dissertation, “Complémentarité des mesures de deutérium et de tritium pour l’étude de la formation des grêlons”, was defended at the Faculté d'Orsay in 1974).

His professional activities have led to his occupying a number of positions: first as a research engineer at the Laboratoire de géochimie isotopique (CEA/Saclay-IRDI/DESICP, then DSM/DPhG/SPER) from 1974; he was appointed director of the same laboratory from 1986 to 1991, then assistant director of the Laboratoire de Glaciologie et Géophysique de l’Environnement (LGGE, CNRS/Grenoble) from 1989 to 1995; he was the assistant director of the Laboratoire de Modélisation du Climat et de l’Environnement (LMCE/CEA), from 1991 to 1996 and head of the LMCE in 1997; he was the leader of the “Climate” group at the Laboratoire des Sciences du Climat et de l’Environnement (LSCE, UMR CEA/CNRS) from 1998 to 2000; and he has been the director of the Institut Pierre-Simon Laplace since 2001. He has also been the director of research at CEA since 1995.

On the national and international stage, Jean Jouzel has, or has been: a member of the PAGES (PAst Global changEs) international scientific program from 1988 to 1995; a French delegate to the first working group of the IPCC (International Panel on Climate Change) since 1994; an expert of this group (second and third reports) and is now an acting member of its bureau. He has also been a member of the French Committee on polar environment since 1994, the president and executive director of EPICA (European Project for Ice Coring in Antarctica) from 1995 to 2000, a member of the Steering Group of CLIVAR (Climate Variability and Predictability) and of the “World Climate Research Program” project from 1996 to 2001, a CEA delegate in the LESC (Life and Environmental Sciences) committee of the European Science Foundation from 1995 to 2000, a member of the CCSPE (Comité Consultatif des Sciences de la Planète) since 1999 and president of the board of trustees at the Institut Polaire Français Paul-Emile Victor (IPEV) since 2000.

Jean Jouzel is also a member of a number of academic societies (including the Geophysical Union and the International Glaciological Society), and a member of the Academia Europea since 1990. His distinctions include the Philip Morris Prize in 1992 on climatology, Chevalier de l’ordre national du Mérite (1993), Docteur Honoris Causa at the Université libre de Bruxelles (1997), Flint Lecturer (Yale University, 1996), Milankovitch Medal (European Geophysical Society, 1997), Prix de l’Académie des sciences (Prix CEA, 1999) and the Ippolito Award (Italian Academy of Sciences, 2000). Jean Jouzel has authored or co-authored more than 250 publications, of which approximately 200 were published by top level international journals (more than 30 were published by the journals Nature or Science), making him one of the most quoted authors in the field of universe sciences.