François Durand-Dastès at his home in the 17th arrondissement of Paris on November 23, 2021. © Géographie-cités
An interview with François Durand-Dastès, geographer and climatologist
François Durand-Dastès was asked by Total to write a contribution to the company’s internal magazine in 1971. In this article, entitled “Atmospheric Pollution and the Climate,” he denounced the negative impact of fossil fuel production on the climate and the prospect, in the long term, of global warming due to human activities. This article is the starting point for a study published by two historians and a sociologist in the scientific journal Global Environmental Change in November 2021, showing that Total Energies, although aware of the risks as early as 1971, questioned the scientific data that threatened its activities. In this interview, the geographer and climatologist returns to some of the fundamental concepts developed in this article and offers some lessons that can be learned from it now.
Born in 1931, François Durand-Dastès is a professor of geography at the University of Paris 7 and a recognized specialist in India and climatologist. His research work focuses on water, industrialization and the ecology of human societies. François Durand-Dastès is a member of the Géographie-Cités laboratory.
Géographie-cités: When Total asked you to contribute to this issue devoted to the environment, were you known as a specialist in climate and global warming?
François Durand-Dastès: In 1971, I was an assistant professor at the University of Paris 7, where I taught climatology and the circulation of pollutants. I had studied climatology for ten years and made my first trip to India in 1961, to Puna where the India Meteorological Department (IMD) was located, which was one of the meteorological centers specialized in tropical cyclone forecasting for the Indian Ocean and all aspects of the Indian monsoon.
At that time, there was not so much talk of global warming but mostly of pollution, the major themes being particulate matter and acid rain, which was very harmful to forests and the mechanism of which seemed very unfair, since the acid deposition was outside the region of origin. Pollution levels were often explained, particularly in the press, by the volume of pollutants discharged locally. However, other factors, sometimes largely neglected, come into play: horizontal and vertical air movements, which condition the dispersion or concentration of pollutants in the local atmosphere. The concentration of pollutants is favoured by the absence or weakness of “synoptic wind”, and/or by the stability of the air mass, which depends on its vertical thermal structure… I mention the essential role of these factors for pollution in the Total information article, and I give a lot of space to the problem of vertical stability.
Géographie-cités: You mention climates with a high pollution potential and cite the case of Los Angeles, one of the most polluted cities in the world. Can you explain the mechanisms involved in this phenomenon?
François Durand-Dastès : In the first half of the 20th century, industry developed in regions that benefited from fairly rapid air circulation. Los Angeles, often cited at the time for its high levels of pollution, was a significant but still quite rare case of a city with strong sources of pollutants (factory emissions and heavy automobile traffic),
One question remained, however, which I posed in the 1971 article: what would happen when industry and other sources of pollution, such as automobile traffic, moved into regions topped for months by anticyclones in which the air, which is very stable, creates a halo of pollution, especially over cities?
These fears have been largely confirmed since then, for example by the severe pollution episodes in Delhi or Beijing – among others.
In this article I did not use the term greenhouse effect but I describe very clearly how it works. The greenhouse effect is a condition of life on earth. The serious problem today is the “additional greenhouse effect”, that is to say the increase of this effect by the increasing emissions of “greenhouse gases”, in particular carbon dioxide, which plays a great role in the thermal balance of the atmosphere because it acts on the absorption of the long wave radiation emitted by the earth’s surface, heated by the short wave radiation coming from the sun.
We always talk about CO2, but there are other greenhouse gases. We often forget to mention a very important one, water vapor. Its role is very complex, because water changes state in the atmosphere. There is a whole set of contradictory processes. On the one hand, water vapor and clouds increase the greenhouse effect because they contribute to the blocking of outgoing long wave radiation. But on the other hand, clouds reflect the “incoming” shortwave radiation, and thus slow down the heating of the planet. Meteorologists have found it difficult to establish the balance of these opposite effects.
In addition, water vapor functions as a “fuel” for atmospheric circulation. Evaporation is conditioned by an absorption of heat; heat which remains in a latent state in the water vapor and which reappears at the time of condensation (One speaks about “release of latent heat”). This mechanism plays a big role in important meteorological phenomena. An example is the tropical cyclone: air which is heavily charged with water vapour over a warm tropical ocean moves towards a small depression; an upward movement starts, and it intensifies rapidly thanks to the release of latent heat; in its turn, the upward movement intensifies the depression, thus the arrival of humid air etc. This is how a “positive interaction loop” works, at the origin of very violent phenomena such as tropical cyclones, but also, for example, the storms of the Mediterranean fall. It is not impossible that the more strongly positive radiation balances due to the additional greenhouse effect accentuate these violent phenomena.
Géographie-cités: What was Total’s reaction to this article?
François Durand-Dastès: Total published the article without modification, I think I remember that I was paid. You have to put this publication in the context of the 1970s: at that time, the major political objective was to ensure France’s energy independence, which meant that fossil fuel production had to be handled by a French company. Environmental issues were just beginning to attract the attention of decision-makers and public opinion. The “Meadows report” dates from the summer of 1971 and the book that resulted from it, “the limts of growth” was published the following year.
Géographie-cités: How do you view the climate situation today? What urgent measures should be taken in the next few years to contain global warming due to anthropogenic actions, particularly the consumption of fossil fuels? Which energy source(s) should be favored?
François Durand-Dastès: The climate situation is undoubtedly worrying, and we cannot imagine today that the additional greenhouse effect will not modify certain balances on a global scale and have major effects. Climate scepticism” is no longer possible. However, we should avoid automatically associating the word “climate” with the word “change”, as the press tends to do. The influences of the climate, its characteristics and its fluctuations, are an ancient phenomenon.
On the other hand, it is regrettable that there is a dimension that is often neglected: the demographic growth: humanity, with seven billion people, needs energy.
However, most of the energy produced in the world is still produced by burning carbon. In particular, a large part of the electricity is produced by these combustions, sources of CO2. We forget too much that the electric car certainly reduces the emission of particles but has only a limited effect on global warming if the energy it uses comes from thermal power stations. Except in regions where the production has other sources than combustions, such as the decay of the atom or hydro-electricity. Thermal power plants should be eliminated. But what to replace them with?
The wind? Wind power is not very efficient and poses the huge problem of the raw materials used to manufacture wind turbines, in particular rare earths.
Tidal energy is very powerful but its “capture” requires complex infrastructures. Only one tidal power plant has been built in France, the one of La Rance, several decades ago.
The direct capture of solar energy requires large spaces, and is not efficient under all latitudes.
Nuclear energy poses the difficult problem of waste treatment.
As for biomass, its exploitation is possible but it takes a resource with limited renewal speed. In the past, wood heating has been the great destroyer of forests.
Doesn’t the character of Astrov, in Chekhov’s play Uncle Vanya (1896) [a doctor who plants trees and counts them (editor’s note)] already say: “When I hear my young forest rustling, planted with my own hands, I am aware that the climate, too, is in my power to some extent and that if, in a thousand years, men are happy, well, it will also be, to some extent, my fault“? An then, he advocates the opening of coal mines in Russia to save the forests…
The solution would undoubtedly be to save energy. But the population has energy needs that cannot be denied. India, in 1955, had 500 million inhabitants, it has 1.4 billion today and yet, the food situation is rather less bad, thanks to the agriculture resulting from the “green revolution” made possible by irrigation, pesticides, the use of chemical fertilizers and improved varieties, energy consuming techniques. Each of these components of the system has its drawbacks and other solutions are sought. But if it is necessary, as we often say, to “produce better”, it is impossible to produce less. We do not have the right to tell the Indians to produce less, they cannot produce less!
Géographie-cités:: You conclude your article with a call to integrate thinking on climate and pollution into urban planning solutions and industrial planning: “Research on the relationship between climate and pollution should make it possible to better understand the costs that it imposes on communities; it can also be used to suggest urban planning solutions and industrial planning solutions that are often less expensive than systematically treating sources of pollutants – and undoubtedly more effective in many cases. What would be the most effective ways of making progress in these areas?
François Durand-Dastès: Today, we place a lot of hope in urban forests, the “greening” of cities, green walls… Greening cities is certainly an urban planning solution that would help avoid extremely uncomfortable situations for city dwellers. Heating, facades that “trap” radiation in a way, everything contributes to creating urban heat islands. But vegetation reduces heating.
As far as industrial planning is concerned, there has been a lot of talk about relocating pollution sources, taking into account the direction of the prevailing winds. It seems that the development of filters and more generally the evolution of techniques has played a more important role than was imagined in the 1970s.
See also: Géographie-cités: Science Vs Lobbying: Total, Elf and Climate Change, 20 octobre 2021.
