A forge. By Fernand Cormon. 1893. Musee d'Orsay, Paris • WIKIPEDIA COMMONS Interview with Jean-Baptiste Fressoz, Historian of Science,researcher at CNRS and professor at EHESS. History &Civilizations: We now agree that we are experiencing climate change. But how does this differ from previous climate changes that the Earth has experienced? JEAN-BAPTISTE FRESSOZ: First of all, the current climate change is extremely brutal, much faster than what humans have experienced in the past. The average temperature of the Earth has already increased by almost one degree since the end of the XIX e century, and it will increase again by at least 2°C (and probably much more) by 2100. This is unheard of! The other major element that distinguishes this climate change from previous ones is that, for the first time, man is the main cause. This is what allows us to say that we have entered the Anthropocene. Can you give the definition of this term:“Anthropocene”? It means man – anthropos in ancient Greek – is now the main factor in the geological evolution of the planet. It was the Nobel Prize in Chemistry Paul Crutzen who coined the term in 2000. He considers that after the Holocene, that is to say the geological period that began 12,000 years ago, at the end of the last ice age, a new geological time opened up as a result of human activity. The main interest of this concept is that it makes it possible to avoid the expression “environmental crisis”. Indeed, a crisis defines a short time, from which it is possible to get out. Our situation is quite different:we have entered a new era in a definitive way, with no possible turning back. When should this new geological epoch begin? There is a lot of debate about this. Paul Crutzen considers that 1784, the date of the patent for the improvement of the steam engine by James Watt, is a good starting point. This date highlights the role of the industrial revolution in entering the Anthropocene. It also makes it possible to emphasize the role of fossil fuels, primarily coal, in climate change. It is indeed the consumption of these energies which is at the origin of the exponential emissions of CO2 , whose crucial importance in global warming is well known. The disadvantage of this date of 1784, on the other hand, is that it is a little too symbolic; it leaves no directly visible trace in the geological archives of the planet, which are, for example, ice cores. We have therefore tended to focus on 1945, the date of the explosion of the first atomic bombs, which led to the emission of radionuclides that can be detected in the stratigraphic analyzes of the soil. The problem is that these radionuclides do not have a central role in global warming, which is the key question... The growth of the Trente Glorieuses is causing an explosion in greenhouse gas emissions, and therefore an acceleration of climate change. But other starting points have also been proposed. But 1945 has another argument to make:it was on this date that the Trente Glorieuses began, this period of rapid growth for the economies of many countries, especially Western ones. This growth is causing an explosion in greenhouse gas emissions, and therefore an acceleration of climate change. But other starting points are also available. Some have suggested that the Anthropocene began 6,000 years ago in China, because it was at this time that rice began to spread there, a crop which, compared to other cereals, is at source of high methane emissions. In the context of the distribution of the efforts to be made between the different countries to fight against global warming, this date is obviously not insignificant. Ultimately, it is difficult to give a precise starting point for a geological evolution, even if there is consensus on one point:CO2 emissions. increase exponentially with the industrial revolution and explode after the Second World War. When did we become aware of the influence of human activity on the climate? We usually hear that it is only in recent decades that, under the aegis of scientists, we have grasped the role of man in the evolution of the climate. The first studies on global warming date back to the 1960s, the importance of the human factor on this evolution was proven in the 1970s, and the scientific consensus on the question became complete from the 1990s. a recent realization is not quite right. At the end of the 18 th century and during the first decades of the 19 th century, in Europe and North America, much attention is paid to the climate, because it is considered that the deforestation of Europe has a direct impact on temperatures and precipitation. We have to imagine that changes in the climate are crucial for societies that are still largely agricultural. From a religious point of view, we are also very afraid of altering Creation, the order of which is willed by God. More generally, the environment was a major concern at the end of the 18th th century. In the medical field, the ideas of Hippocrates are then authoritative, and close links are established between the state of health of populations and the pollution they may suffer. However, all of this fell into oblivion during the 19th th century. How can we understand that we have then ceased to be interested in the question of the links between human activity and the environment? There are several reasons for this. On the one hand, Hippocratic medicine is supplanted by other medical theories, which explain the state of health of individuals by their social situation rather than by their environment. Sociology follows suit in this evolution:it makes Montesquieu's theory of climates a foil and is based on a regime of social rather than environmental causality. Regarding the effect of human activity on the climate, scientists in the second half of the 19 th century identify the existence of ice ages in the geological history of the planet. We do not imagine that man could have been at the origin of such climatic upheavals, and we therefore come to the idea that there is no link between human activity and geology. With the Anthropocene, we now know that this last conclusion is no longer correct. The Anthropocene is the consequence of human activity. But are all men equally responsible? Obviously not, and this is one of the pitfalls of explaining climate change by human activity in general. We then tend to consider that humanity, taken as an undifferentiated whole, is collectively responsible for the state of the planet. It's totally false ! If we look at things from a historical perspective, we notice that some countries have a very large share in the current situation. This is particularly the case for the United Kingdom and the United States, since it was not until the 1980s that CO2 emissions cumulative of these two countries are exceeded by those of the rest of the planet. In truth, the Anthropocene is largely an “Anglocene”! Today, the ecological footprint of the inhabitants of the planet varies completely:between a rich person from a rich country and a poor person from a poor country, the ratio is 1 to 1,000. It is also necessary to take into account the relations that exist between the regions of the world, in particular the fact that, on a planetary scale, the industrialization of the center could only be achieved by relying on the looting peripheral resources. For example, the steam engine that launched England into the industrial revolution is mainly used in the textile sector. However, the cotton that supplies the factories is of course not English; he comes from the slave plantations of the American continent. Similarly, the development of Western economies during the Glorious Thirties required the extraction of raw materials in Third World countries, such as rubber, essential for the automotive sector. There is a tendency to consider humanity, taken as an undifferentiated whole, to be collectively responsible for the state of the planet. However, some countries, such as the United Kingdom and the United States, have a very large share in the current situation. The Anthropocene is largely an “Anglocene”! It is thus striking to note that, since the beginning of the XX th century, the forest has stopped shrinking (or has even progressed) in Western countries, while Asia, Africa or South America have experienced rapid deforestation. It is because the West has stopped degrading its own environment in order to seize the resources of its colonies and the least developed countries. It is necessary to specify here that, if the communist States, starting with the USSR, were at the origin of ecological disasters – it is enough to think of the drying up of the Aral Sea –, the functioning of their economy was mainly based on the use of their own raw materials, and not those of other countries. In developed countries, how can such a rapid increase in CO2 emissions be explained? per capita over the last two centuries? This is mainly due to the development of mass consumption. At the turn of the 19 th and XX th centuries, it becomes imperative to find outlets for a capitalist industry that produces ever more:the ordinary man is therefore transformed into a consumer. On the other hand, consumption is a very effective means of disciplining the workforce. A worker who wishes to acquire a new object will be a more obedient worker, especially if he has taken out credit. And so it was that the invention of consumer credit went hand in hand with an unprecedented boom in the automobile industry – polluting if ever there was one – in the United States of the 1920s. CO2 emissions are primarily linked to the consumption of fossil fuels. How did these energies impose themselves? Their triumph was not inexorable. When the steam engine appeared in British factories in the 1820s, coal was even more expensive than the hydraulic energy used until then. However, for two reasons, manufacturers are choosing coal. On the one hand, hydraulic energy required an arrangement between the various actors upstream and downstream to distribute the energy of a watercourse, and industrialists no longer want this collective organization:coal is an expensive way to be quiet. On the other hand, the energy of the river does not allow a sudden increase in production, whereas coal allows such an adaptation of the activity, for example in times of high prices. The development of oil is directly the result of political choices. At the end of the Second World War, European industries functioned mainly thanks to coal, present on the spot and much cheaper than oil. But it is European workers who extract it, which gives them strong bargaining power in the event of social conflict. A widely followed strike would even allow them to shut down the economy. In a context of the nascent cold war, while the communist parties of several Western European countries are very powerful, this situation frightens many people, especially the leaders of the United States. The Marshall Plan established by the United States in 1948 allows them to promote the purchase of oil by European countries, in order to considerably limit the power of trade unions. These examples make it possible to ask the right questions for the future:what are the interests that, tomorrow, could make us switch to renewable energies? Find out more The Anthropocene Event. The Earth, History and Us, C. Bonneuil and J.-B. Fressoz, Points, 2016. Does nature play a role? While current climate change is mainly linked to human activity, natural phenomena also play a role in climate variability. Major volcanic eruptions can thus slightly lower average temperatures for several months, on a regional or planetary scale. This is explained by the propulsion of aerosols (particles that limit the greenhouse effect) in the stratosphere. Variations in the intensity of solar activity also cause slight fluctuations in temperatures on Earth. Finally, the fall of a meteorite can generate debris that clogs the atmosphere and causes temperatures to drop. It was probably such an event that caused the disappearance of the dinosaurs 65 million years ago. C. M. Aerosols to the rescue? Since the sulfur aerosols emitted by volcanic eruptions can lower the greenhouse effect and, consequently, temperatures, some scientists wish to draw inspiration from this phenomenon to fight against global warming. They propose injecting large amounts of sulfur dioxide into the stratosphere to generate a climate cooling effect. It is in particular the Nobel Prize in Chemistry Paul Crutzen who promotes “geo-engineering”. Nevertheless, there is no lack of criticism against this human manipulation of the climate. Sulfur aerosols would indeed considerably reduce the thickness of the ozone layer and, since they are carcinogenic, they would cause hundreds of thousands of premature deaths.C. Mr.
