The White Planet: The Evolution and Future of Our Frozen World

by Jean Jouzel

  After the first scientific fieldwork on the ice sheets (at the beginning of the 1950s in Greenland and during the IGY in Antarctica), we became aware of the volume of that ice whose melting or extension has caused the sea level to vary by up to 120 meters during the Quaternary. Repeating the long drifting of the Norwegian explorer Fridtjof Nansen, a voluntary prisoner of the ice shelf in the Arctic in 1895, stations drifting on the ice, then submarines, have enabled us to define the very large expanse and the thinness of that ice shelf. Considerable progress was then achieved with the use of satellites, which enabled us to inventory the “White Planet” and its evolution.

  Measurements of the quantity of CO2 in the atmosphere began during the IGY, but it was in the 1980s that the ice core drilling undertaken in the heart of Antarctica enabled us to show for the first time the connection, during the last few hundred thousand years, between the climate and the amount of greenhouse gas in the atmosphere. We were also able to prove the rapid and large rise of the greenhouse effect in the last two centuries, which the IPCC concluded was likely the major cause of the climate warming of the last few decades. The increase in the concentration of greenhouse gases in our atmosphere since the beginning of the industrial era is moreover only one of the aspects of the degradation of our environment on a planetary scale.

  The use of new techniques has also been applied to life sciences. Thus after the discovery of a rookery of emperor penguins in Adélie Land at the beginning of the 1950s, ultraminiature signal receivers later enabled scientists to follow by satellite the emperor penguins in their long march over the ice shelf and their plunging into the water, and to study their collective behavior that ensures the survival of the group as well as that of individuals.

  The International Polar Year 2007–2009

  For the 2007–2009 IPY, the idea was to take the pulse of these regions and to study their role in the Earth’s system. The focus was on the current problems of society in which the polar regions play an essential role (environment, climate, biodiversity, future of local civilizations, etc.). It also opened onto fundamental research in new horizons, going from the infinitely small (microbiology) to the infinitely distant (astronomy), which will feed the discoveries of the future.

  We may of course be surprised by the need to concentrate research on an international level on a given geographic zone during a period that lasted only two years. The choice of the poles is tied to the importance of the ice there in one of the great current challenges of our society: climate warming. To better anticipate what will happen in the future, the two patrons, ICSU and WMO will simultaneously study the two polar regions during an annual cycle. Taking into account the hemispheric disconnect in the seasons and the difficulty in accessing the high latitudes in the winter, the IPY thus unfolded over two years, from March 2007 to March 2009. To be accepted, a program must lean on a large international participation, including China, the United States, Europe, South America, and Australia. In all, sixty-three countries combined their resources in researchers, observatories, oceanographic ships, ice-breakers, convoys over the ice sheets, helicopters, airplanes and satellites, and computers. More than two hundred projects were organized around major themes such as the study of climate warming and its impact on the ice, biodiversity, and populations in the Arctic, which are also subjected to great socioeconomic changes—so many societal concerns in a world in full evolution. The work of the scientists has been spread by many systems in order to inform citizens and policymakers and to attract a new generation of researchers.

  As climate warming and its impacts are very marked in the polar regions, it is logical that many IPY programs involved the role of those regions in the global climatic system. In the Arctic, the increase in temperatures is two to three times more marked than on average around the globe and, as we have mentioned, many impacts are already visible: the degradation of infrastructures with the melting of the permafrost; the threatening of the resources of the local populations whose subsistence depends on fishing and hunting; and the threatening of species, such as the emblematic white bear. In Antarctica, following the retreat of the ice shelf around the peninsula, the observation of the Southern Ocean floor has, since the beginning of the new polar year, enabled scientists to discover ecosystems of exceptional wealth, including thirty or so new species.

  Other programs involve more basic research. The “Ice Cube” project at the South Pole looks at the infinitely distant by using the perfect transparency of the deep ice to detect cosmic neutrinos from the weak bluish luminous trails they leave in their path and, from there, to attempt to determine their source in the universe. With this goal in mind, a network of detectors was implanted in a volume of ice from one cubic kilometer to a neighboring depth of two kilometers.

  The French contribution to the IPY is very significant including, among other places, in the Arctic, with the study of glaciers, the ice shelf, and pollution, and in Antarctica with the resumption of exploratory fieldwork, new ice core drilling, and the development of scientific activities at Concordia Station in the heart of the ice sheet. We cannot discuss all of these projects here, but we would like to share the approach of and the hopes for three of them, in which we are involved in various ways. We will first mention the scientific objectives in the realm of glacial ice core drilling. Then we will discuss the research on traces of life in Lake Vostok, which is under nearly four kilometers of ice; even if, for the moment, no water has been extracted from the lake, plans to do so exist, and an analysis of the deepest ice of the Vostok coring formed by the refreezing of the subglacial lake water has already opened paths in which Dominique Raynaud has, with colleagues from Grenoble and Russia, been very interested during the last few years. Finally, beyond its undeniable aesthetics, the Franco-Italian Concordia station is an ideal base for research in numerous disciplines; two of us, Claude Lorius and Jean Jouzel, have had the privilege of following its creation, as presidents of the administrative council of the French polar institute. The station’s genesis owes a great deal to the involvement of both groups’ successive directors, Roger Gendrin and Gérard Jugie, and to Mario Zuchelli, their Italian counterpart.

  Glacial Ice Coring: Ambitious Objectives

  Each core drilling in the ice provides new elements for describing and understanding the evolution of the climate. Over the next decade, the main priority of the internationanl community of glaciologists is to deepen the inquiry from data of the past. This community proposed and created the International Partnership in Ice Core Sciences (IPICS) with four targeted projects.

  The first is to obtain a complete record of the last interglacial period in Greenland or an ice core covering at least the last 140,000 years, which that of North GRIP was not able to provide, as it stopped before 125,000 years and revealed nothing of the conditions that prevailed in Greenland during the next-to-last deglaciation. The research of the optimal core site to the north of North GRIP began with the IPY in 2007. As already mentioned, this new international drilling project led by our Danish colleagues under the directorship of Dorthe Dahl-Jensen was completed during the summer of 2010. This project, for which Valérie Masson-Delmotte has taken responsibility vis-à-vis French participation, should enable a better understanding of the evolution of the ice sheet of Greenland during the preceding interglacial period; it is important because the climate, which was warmer than what we are currently experiencing, had caused a reduction in the volume of ice, but no one really knows in what proportion.

  Going back further in time enriches our knowledge, as has been shown in the extension of the time scales between the recordings at Vostok and those of Dôme C. From this perspective, the second project consists of researching one or several drilling sites in Antarctica that will enable us to gather climate archives at least 1.2 million years old. Why that objective? Quite simply because marine sediments from that era reveal a transition between glaciations that were less intense and had a periodicity close to 40,000 years and more marked climate cycles occur
ring every 100,000 years. Only the glacial archives are able to describe the evolution of Antarctic temperatures, the composition of the atmosphere, and the correlation between climate and the carbon cycle during that true climatic revolution of the middle of the Pleistocene, whose origin is far from clear. The hypothesis of a connection between that major transition in the rhythm of glaciations and a long-term change in the atmospheric concentration of carbon dioxide could finally be validated. But first we must identify the sites likely to contain ice that is that old, a priori in regions where accumulation is the smallest possible and where the thickness of the ice is great and flow rate very low. It requires considerable logistical effort to explore the coldest and driest regions in the center of Antarctica. Scientific fieldwork, in particular by IPEV, going from the great drilling sites, Dôme C and Vostok, to the region of Dôme A, a priori the most promising sites (Figure 1.2), will be carried out in that spirit of exploration. A first shallow ice core has recently been taken by our Chinese colleagues.

  To go back as far as possible in time, to break records, is fortunately not the only goal of glaciologists. Thus the last 40,000 years are the object of the third project and of the greatest attention because that period encompasses both the rapid and great variations (of which we are far from having solved all the mysteries) and the last deglaciation. This explains paleooclimatologists’ great interest in a series of ice cores covering that period both in Antarctica and in Greenland. The major challenge will be to construct the most precise chronological framework possible by using the different markers present in ice, which can be used to such a series of ice cores, such as variations in the concentrations of greenhouse gases and dust, and then—this is essential, in particular vis-à-vis the uncertainties that concern the future rise in sea level—to understand the response of the large ice sheets to a warming as great as the one that accompanied the last deglaciation. Ice core drilling in the coastal regions of Antarctica can enable us to follow the evolution of the ice cap and its flow during that period. That of Talos Dome, which ended successfully at the end of 2007, fits perfectly within these objectives.

  Finally, with the fourth project, glaciologists are interested in the last 2,000 years in view of reconstructing the climate on a very detailed temporal scale, in some cases year by year, but also for measuring the evolution of the ice mass in relation to the rise in sea level. Beyond Greenland and Antarctica, data of this type can be obtained from many glacial ice caps in Arctic regions and from high-altitude glaciers in low and mid-latitudes that are not affected by melting.

  The Microbiology of Ice and Subglacial Lakes: Life in an Extreme Environment

  We often say that biology will be the science of the twenty-first century. What if that also applied to the vast deserts of the white planet? The story begins in Paris in July 1955. Eleven nations were represented to prepare the International Geophysical Year 1957–58. The countries involved essentially were researching the coastal sites in Antarctica to establish their research stations there because they would be easier to access than more inland sites. France installed the Charcot base at 320 kilometers from the coast, but the two giants, the United States and the Soviet Union, with more ambition because they had more means, also proposed the South Pole. The United States, which had been the first to express interest in that emblematic site, established a site at the pole. The Soviet delegation, which had arrived late in Paris because at that time obtaining permission to travel to the West was not an easy task, was disappointed. And if we are to believe Igor Zotikov as he relates in his book,1 it was perhaps a bit out of spite and to show their ambition that the Soviets chose the place that is farthest from any coast: the pole of inaccessibility, close to the geomagnetic pole. Ten enormous treaded Kharkovchanka vehicles left Mirny Station on the coast in the direction of the geomagnetic pole, which they reached on December 16, 1957. Vostok Station was born. That station has offered glaciologists 420,000 years of climate archives; a wise choice indeed.

  Without the Soviet delegation’s late arrival to the meeting in Paris, the discovery and the destiny of the largest subglacial lake in Antarctica would no doubt have been different. The Soviets established their Vostok base on the high plateau of East Antarctica without knowing that under their feet and under around four kilometers of ice was a huge lake with a surface equivalent to that of Lake Ontario. At the time theoreticians could already foresee that because of the geothermal flow emitted by the rock base, the temperature of the ice could likely reach the point of fusion under several kilometers of ice, despite the extreme temperatures that existed on the surface. But from that to imagining the existence of a gigantic lake some hundreds of meters deep—no one had made that leap.

  In the 1970s subglacial lakes were discovered in Antarctica by a team from the Scott Polar Research Institute of Cambridge University directed by Gordon Robin.2 With the goal of studying the structure of the inland ice sheet, that team made a series of flights with American C130 airplanes using a new method of radiography of the ice sheet with radar equipment implanted in the plane; the radar emitted radio waves that penetrated into the ice and were reflected by the different layers encountered, including the rock base. Imagine the surprise of this team upon observing over some of the many radar images covering a large region of East Antarctica that the rock base, generally irregular, was interrupted by extremely flat zones. Because water reflects the radar waves of low frequency of a rock base more strongly, Gordon Robin attributed these horizontal echoes to the presence of subglacial lakes. During this period of intense aerial radiography of the Antarctic continent, many flights were taken in the Vostok region using the station to facilitate navigation. Many “flat echoes” were recorded, which led to the suggestion in 1977 of the presence of a huge subglacial lake in that region. That marked the discovery of Lake Vostok.

  In 1991 the launch of the European Remote Sensing satellite 1 (ERS 1) opened a new chapter in the saga of Lake Vostok. The eye of the satellite was able to describe in detail the topography of the surface of the ice sheet, and manipulating the satellite images then caused the incline of the surface to appear in different colors, thus demonstrating the zones that had almost no slope. A zone of this type, of around 230 kilometers in length by 40 kilometers in width, was drawn at the place where the existence of Lake Vostok was indicated from the observation of radar waves. It was the imprint of the surface of the lake that lay under four kilometers of ice. The existence and the position of the lake were thus firmly established by the following evidence: the basal temperature rose under four kilometers of ice—confirmed by the measurements of temperature carried out in the core hole of Vostok—and flat topographies at the ice-lake interface. At the time definitive evidence was still lacking, that is, having a sample of the water from the lake. But since 1998 biologists who work in extreme conditions have had access to the ice formed from the water of Lake Vostok, the refreezing of which is found over a span of 80 meters in the deep part of the ice cores.

  Biologists’ interest grew as the story of Lake Vostok unfolded. The pioneers were indisputably the Russians, especially the Institute of Microbiology of the Academy of Sciences in Russia, but researchers’ interest in the lake intensified when a part of the refrozen ice became accessible. Although it was difficult to extract data about the lake composition from this refrozen ice, that lake ice could provide precious information on subjects as fundamental as the development of primitive life in an extreme environment. Imagine life under 400 bars of pressure, around 0°C, and in the absence of solar energy and light! Could a living organism adapt to such conditions? The stakes go beyond the fascinating search for traces of life in those conditions when we consider the possible presence of a subglacial ocean covered with dozens of kilometers of ice on the moon Europa of the planet Jupiter. How can we not imagine Lake Vostok as a reduced, analogous model and even as a field of experimentation with a view toward the exploration of signs of life on other celestial bodies, like Mars or the Moon, on which scientists
do not exclude the presence of water? This research could also be applied to the realm of genetics.

  Within the framework of a collaborative agreement between the Russians, Americans, and French, they all have access to accreted ice samples from the lake. In the same issue of the journal Science, two international teams led by American researchers John Priscu3 and David Karl4 provide astonishing revelations demonstrating relatively high microbial concentrations in the accreted ice and conclude that Lake Vostok could contain viable microorganisms, even though it has been isolated from the atmosphere for more than a million years.

  At the same time the Russians and French combined their efforts within the framework of a consortium that brought together glaciologists and microbiologists under the direction of Jean-Robert Petit from the LGGE and Sergey Bulat, microbiologist at the Saint Petersburg Institute of Nuclear Physics. They first demonstrated the need to use specific methods of decontamination, which had already been developed by glaciologists to measure certain trace elements in the ice cores. The application of these “ultraclean” techniques indicates that the density of microorganisms revealed in earlier publications is quite likely overestimated and that the accreted ice is a biological semi-desert. However, in 2004 a work by Sergy Bulat and colleagues held a large surprise by revealing the existence in that desert of a few thermophilic bacteria (which like the heat) whose closest “cousins” have been identified only in deep ditches or hot-water sources far from Antarctica.5 It is difficult to suggest a contamination there; it is more likely that those bacteria prove the existence of hydrothermal sources in the deep crevices that could exist at the bottom of the lake, sources that have been proven thanks to the isotopic analysis of the helium trapped in the deep ice.