by Jean Jouzel
This was only the beginning of a long story and of a contribution that will certainly hold great surprises in biology, the science of the twenty-first century. The next step was to extract water from the lake. There was very strong interest among microbiologists in obtaining samples of that precious water because the accreted ice at the moment of its formation could have discriminated among the microorganisms that it accepted within its crystalline system and thus not be perfectly representative of the composition of the lake. But access to the lake raised a major problem, that of its contamination the moment it was penetrated, since the borehole was full of kerosene to prevent its closure over time. As described in chapter 6, the Russians penetrated the lake on the morning of February 6, 2012, likely with a minimal risk of contamination, as revealed by the water rise of about 600 meters above the lake surface in the drilling hole. Vladimir Lipenkov’s words bear repeating: “Such was the end of the 5G drilling, but hopefully not the end of the Vostok project.”
The Russian team plans to come back at Vostok next season (2012–13) and to start coring the 600 meters of refrozen lake ice in the hole. There is no doubt that a new step in the Vostok saga will be the discovery of the hidden world of Lake Vostok.
There are many subglacial lakes in Antarctica that are in general much smaller than Lake Vostok. So, why not try to test less risky penetration technology in one of these smaller lakes? Indeed there are new projects of penetration in such lakes, proposed by other nations (e.g., United Kingdom, United States). This is perhaps not as easy as it sounds because the limited amount of water in a small lake could be more sensitive to contamination. And above all, we now realize that there is a true subglacial hydrology that might connect several lakes.
The lake is only part of the cornucopia sleeping under the Vostok ice. Another part is what is formed by hundreds of meters of lake sediment accumulated throughout time at the bottom of the lake. This is an area of research for the next generation of scientists interested in the secrets of Antarctica.
Concordia: A Station Full of Promise
Who doesn’t recognize those two elegant cylindrical buildings connected by a passage, lost in the middle of the huge Antarctic expanse, more than 1,100 kilometers from the French base Dumont d’Urville and 1,200 kilometers from the Italian base Terra Nova Bay? Made up of two main buildings three stories tall and having a total area of 1,500 m2, the base was completed in 2005. The two buildings, constructed on stilts, were respectively dedicated to so-called calm (bedrooms, laboratories) and noisy (kitchen, restaurant, workshops) activities. The base can accommodate around fifteen people, scientific and technical personnel who must live in complete autonomy for nine months of the year; there is an annexed camp that can accommodate an additional forty people during the southern summer. The station can be reached only during a window of about ten days in the summer by ground convoy starting from Dumont d’Urville or by plane, generally from the Italian coastal base Mario Zucchelli of Terra Nova Bay.
The project took shape at the beginning of the 1990s. A Franco-Italian agreement was signed in 1993 between the polar institutes of those two countries with the objective of constructing a permanent Concordia Station at Dôme C. It was on this site that the European EPICA core drilling project, covering 800,000 years, was carried out during 1996–2005 and during the months of December and January. The deep ice core project, and that of the construction of the base, thus benefited from shared logistics largely provided by the IPEV, which, as heir to a tradition of several decades of French polar expeditions, became expert at getting material to the heart of the Antarctic continent. Thus the construction of the Franco-Italian Concordia Station and the completion of the deep ice core EPICA drilling necessitated the delivery of more than 4,000 tons of material at more than 1,100 kilometers from the coasts and at an altitude of 3,300 meters.
That heavy equipment was transported by ship from Hobart in Tasmania to Adélie Land, transferred over the continent via the ice shelf in winter, and then taken by land convoy within Antarctica. Each year three round-trips were undertaken during the southern summer between the coastal station of Dumont d’Urville and the Concordia site. Each convoy was made up of six or seven traction machines that towed some thirty hauling rigs, including trailers for personnel. All the vehicles and carts of the convoy were designed for use in Antarctica, whether they were tractors, platforms for cisterns, or containers. The average speed of the convoy was about ten kilometers per hour and a round-trip took twenty to twenty-five days. Technical improvements were continually made to increase the efficiency of the convoy while decreasing the impact on the environment (regulating the gases emitted from the motors and reducing the packing of the snow on the road).
An ideal place for glaciologists, Dôme C, which benefits from a particularly stable, pure, and dry atmosphere, was also perfect for studying the chemical composition of the low and high layers of the atmosphere. Researchers focused on the transfer of trace elements between the air and the snow, on the unleashing of katabatic winds, and on following the evolution and the reestablishment of the ozone layer. Because it is far from the coastal regions, Concordia is also ideal for observations in magnetism and seismology, while the isolated and confined living conditions in which a group of winter dwellers coexist are propitious for carrying out biomedical programs applicable to long space flights.
Astronomers and astrophysicists are also very interested in Dôme C. Thus the competition among astronomers worldwide to go ever further in the exploration of the universe’s history and to obtain ever finer details of celestial objects leads to the development of new techniques and to the discovery of new earthly sites that can improve the performance of current technology. The advent of space tools opened a new dimension in the astronomical observation, as did the perfection of the adaptable optics in earthly observatories. These two systems are, however, onerous and have their own limitations in terms of both accessibility and technological progress. An alternative has appeared with the installation of permanent continental Antarctic stations located at high altitude on the plateau. Astronomers are very interested in using these exceptional sites for several reasons: there are long polar nights that at the center of Antarctica extend over several months; there is the conjunction of very low temperatures and the remarkable stability of the lower layers of the atmosphere; and there is an absence of anthropogenic perturbations. The exceptional quality of the site of Dôme C vis-à-vis these criteria has been acknowledged; the only potential competitor is the site of Dôme A, where a permanent station has not yet been built. Thanks to Concordia Station, two great research projects could be rapidly developed at Dôme C: the detection of planets similar to ours (exo-Earths) and that of traces of the first moments of our universe in the cosmic depths.
But it is time to return to Earth and even into the ice to discuss our planet.
CHAPTER 17
Humans and the Rise of Pollution
The degradation of our environment is one of the greatest challenges facing our society. With an increase in population from 1.6 billion in 1900 to 6.6 billion at the beginning of the twenty-first century, with all of its needs and activities, the impact of humans on the planet is now more than worrisome. That impact is manifest both on a local scale, very close to sources such as the great megacities of the industrialized countries, and on a global scale. To increase our awareness of this and to evaluate the state of the health of our environment, we can examine the polar ice caps, which, despite their apparent purity, contain rich data. In those desert and distant zones, they have recorded the rise of pollution and the global nature of the impacts of our activity, a story that should lead us to serious reflection. Let’s look at a few aspects of this story.
A few centuries ago explorers and naturalists realized that the equator did not represent a border between the Northern and Southern hemispheres. Going to the high latitudes of the two ends of the planet, they observed the flight of the Arctic stern birds migrating with the seasons and
sighted the great humpback whale as far as the great South, animals guided who knows how in their flight and their swim. These observations suggested that we have only one atmosphere and one ocean.
For the glaciologist of polar regions, the first unexpected discovery came from the observation of magnificent boreal and southern lights that over the course of a few months went from the nights of the ice sheet of Greenland to those of Antarctica—a phenomenon whose study dates from the International Geophysical Year fifty-five years ago: high-energy particles from the solar wind were channeled by lines of force from the magnetic field that surrounds the Earth, and it was at the poles that they encountered the gases of our atmosphere, creating colored sheets in high altitudes. That magnetic field surrounds the Earth, protects and isolates it, and it is in that shell that life was able to develop.
In the interior, during campaigns from one pole to the other, glaciologists have been able to discover traces of human activity. Although we live in it—or rather survive in it in all of our large cities—there are glacial archives that reveal the undeniable rise in the pollution of our atmosphere on a global scale since the advent of the industrial era, which began at the beginning of the nineteenth century, well before the installation of scientific measurement networks.
Aerosols, particles suspended in the atmosphere, and gases can be natural or a result of human activity. Some pollutants, gases with long lives, and small aerosols, or those that have reached the stratosphere, travel over great distances and meet up in the polar regions and in their ice. Since most of the industrialized countries are in the Northern Hemisphere, the Arctic is more exposed to atmospheric pollution of anthropogenic origin than is Antarctica, but we will see that this continent is not totally spared. Although heavy metals such as lead, coming from mining activity or from our fuel, have above all marked the Arctic, the greenhouse gases and the ozone hole have reached Antarctica. The composition of the atmosphere has been studied in a continuous fashion for only a few decades—since the International Geophysical Year of 1957–58 for carbon dioxide and more recently for other greenhouse gases or pollutants. The archives contained in the ice are unique and thus indispensable for putting the influence of human beings on their environment into perspective.
It is not always simple to pass from concentrations measured in the snow to those that exist in the atmosphere; however, researchers have been able to decipher the memory of the ice to account for the principal changes that have occurred throughout the years (since the beginning of the industrial age and sometimes beyond) from pits or shallow ice cores. Before going to Antarctica, let’s take a final look at Greenland where researchers have reconstructed many scenarios of the state of the atmosphere.
The Story of Lead
The well-documented history of lead illustrates many facets of pollution. It was Clair Patterson of Caltech in California who was the first, in 1969, to use the archives of inland ice sheets to reconstruct the evolution of that pollutant.1 With his colleague Murozumi, he discovered an increase in concentrations of lead in the snow of Greenland that was particularly marked at the beginning of the industrial era. The extraction process required extremely clean techniques; researchers had to pass into “white rooms” before using specific ultrasensitive methods of analysis. So, in snow from the last few thousand years, 1,000 tons of ice contained only 0.1 milligrams of lead, which came from the dust of rocks or from volcanoes, whereas there was close to 200 times more for the highest recent layers. Pollution seems in this case an inappropriate term, but it is the sensitivity of detection and the global tendency that interest us here. Claude Boutron and his French and international colleagues then improved the technological developments that would advance our knowledge in this domain.2
Thus the ice of Greenland bore witness to very old traces of lead in the atmosphere of the Northern Hemisphere at the height of the Roman Empire. It was, for example, quite marked in the samples dating back 2,000 years that were connected with the exploitation of mineral resources. We then observe a decrease in concentrations that could correspond to the fall of the Roman Empire prior to the year 1000, before increasing again in the Middle Ages. As historians have shown, these evolutions are linked to the quantities of ore extracted from mines. By measuring the different isotopes that make up lead, researchers have been able to identify the major sites of production such as that of Rio Tinto in Spain. Although all of these impurities were emitted on the ground in the form of dust, traces of them have been found thousands of kilometers away in the snow of Greenland; this was no doubt the first revelation of a trace of pollution extending over a large, hemispheric scale.
But the story of lead took another turn during the last two centuries. Although not very detailed, the curve of Patterson and his colleagues, published in the 1960s, demonstrates a strong increase in the amount of lead in the snow of northwestern Greenland, with levels as much as two hundred times higher than natural concentrations. These results had enormous repercussions; they demonstrated that humans were responsible for the undeniable pollution of the atmosphere of the Northern Hemisphere and were the basis for a crusade undertaken by researchers against the addition of lead in gas to improve the performance of automobile fuel. The responsibility of that additive for an increase in concentrations observed was confirmed by the measurement of “organoleads” in the snow that do not exist in the natural environment.
The use of leaded gas began in the 1930s and increased rapidly until around 1970 (Figure 17.1). Other measurements bearing on the isotopic composition of lead enabled us to identify the guilty parties of this pollution: American cars from the 1970s are at the origin of two-thirds of the lead present in the Greenland snow, whereas Europe was the essential source in the 1980s. The United States was the first to respond to the warning of the ice. As a result of pressure from ecologists, unleaded gas gradually caught on and we have returned to more natural amounts in the snow and air of Greenland.
In the great South, the story of lead recorded in the snow of Antarctica has a completely different slant. The concentrations are much weaker than those of Greenland and thus even more difficult to measure. It was only recently that the first traces of pollution from the end of the nineteenth century were identified in the coastal ice cores. These resulted from whaling activity, from ship traffic using coal, and from mining activity in the various continents of the South—far away from the inland ice sheet. But there was nothing alarming in that data.
Other Heavy Metals, Including Copper
From extractions taken in the center of Greenland at Summit Station, French scientists3 were able to reconstruct the history of pollution of the Northern Hemisphere between 1773 and 1992 by analyzing so-called heavy metals. During the last two centuries, concentrations multiplied eight times for cadmium, five for zinc, and four for copper until the 1970s; these coefficients were reduced by about a factor of two during the following twenty years. Despite this improvement, biogeochemical atmospheric cycles were still largely dominated by emissions of human origin at thousands of kilometers from the chemical and mining industrial centers and from sources using fossil fuels such as coal.
The history of atmospheric pollution from copper revealed in the ice of Greenland has also been edifying.4 It shows that concentrations began to exceed natural levels around 4,500 years ago with the rise in the metallurgy industry in the Copper and then the Bronze Age, which combined copper with tin. During the Greco-Roman era, around the fourth century B.C.E., concentrations were on average double natural levels; they remained at that level during the Middle Ages before quickly rising after the industrial revolution. To explain these variations, researchers compiled data published on the production of copper throughout history. According to those data, production began in the Neolithic, around 7,000 years ago, but became significant only 2,000 years later. It then continued developing, culminating first at the height of the Roman Empire. Although copper production decreased in Europe during the medieval era, most of it came from China, no
tably during the Sung dynasty of the North (tenth to twelfth centuries A.D.) during which a second maximum production close to that of the Roman era was reached. Production then decreased again before undergoing yet another strong growth into the present, where it is around nine million tons per year.
Figure 17.1. The snow and ice of Greenland: the lead concentrations during the last two centuries. Measured at the Summit Station at the center of Greenland, the lead concentrations show the increase of metallurgic activity and of the burning of coal and wood since the eighteenth century. Starting in the 1930s, lead additives used in gas in industrialized countries led to concentrations more than two hundred times higher than the natural level as it existed at the beginning of the nineteenth century. A peak concentration was reached at the beginning of the 1970s. Since the introduction of “unleaded gas,” that short-life aerosol has been slowly leaving the atmosphere; it will still take several decades for the glacial archives to show a return to less contaminated air.
This simplified history coincides with the data from the ice, but beyond the raw figures of mining production, the glacial records also include the effect of the techniques used. Until the end of the eighteenth century, those were extremely polluting; 15% of copper emissions into the atmosphere were caused by production methods whereas currently they do not go beyond 0.25%. The data from the glacial archives open a possible (although difficult) path toward a quantitative approach to the history of the production of metals in ancient civilizations; this is an important socioeconomic and political parameter since it controlled in particular the minting of coins and the manufacture of weapons. Returning to recent pollution, the fallout measured in Greenland is on the same order as that in the twentieth and the nineteenth centuries even though mining activity has increased greatly; we see here the beneficial role of technological progress.
