Life on our planet in decline: in the preface to an interview with Sandra Lavorel, ecologist and director of research at CNRS (Grenoble), Audrey Boly recalls her childhood stroll through the countryside, populated by colorful butterflies. Today, for his daughters, this event is to see one passage. The grasshoppers that inhabited our lawns fifty years ago have completely disappeared along with the bugs that used to crash into our windshields while driving. These very simple daily indicators are confirmed by the alarmist data of Science causing a galloping loss of biodiversity on Earth,
in the soil and even in the seas: in one of the previous episodes, we saw that the death of corals affects half of them, threatening the entire biodiversity of the species that made them their habitat. The status of vertebrate biomass is not much better, as it has decreased by 60% over the past forty years. This episode calls into question the reasons for this collapse, the reasons for taking them seriously, and the measures that need to be taken.
If we define ecosystems as “a set of intimate relationships between different species”we understand that an imbalance in one of them can have consequences for others: bird populations are markedly affected by the disappearance of insects – an important part of their food chain – and use of pesticides in agriculture is, according to the scientist, an undeniable cause of biodiversity loss, which also affects plant life due to a decrease in the number of pollinating insects. also questionable growing effect of climate change for all biodiversity and habitat loss (forests, wetlands, agricultural areas, marine environments, soils) that cause a decline not only in insect populations, but also in the number of macro- and microscopic species. As in the marine realm, where overfishing of jellyfish by predators leads to the rapid reproduction of the latter, terrestrial space is subject to the destruction of ecosystems.
Scientists go so far as to talk about a “mass extinction” that is taking place, and Audrey questions Sandra Lavorel about the meaning of the term. The definition requires both the number of endangered species and the rate of extinction: in the evolution of biomass, there have always been species that have become extinct and others that have emerged, with a “base rate” of extinct species of about ten. thousand per century. Estimates vary greatly today, but the acceleration is recognized by all scientists, in a wide range from a hundred to a thousand per century. This will be the sixth mass extinction, the previous ones were caused by various causes, such as severe climatic events (change in the Earth’s axis of rotation) or astronomical events (collision of dinosaurs with a giant meteorite 12 million years ago). ). Today, the threat of extinction is closely linked to the Anthropocene era, when the human species possessed quantity and means (creation of new molecules, exploitation of raw materials, use of pollutants, etc.). have a massive and negative impact on the environment and biodiversity. Scientists have calculated that a million species could become extinct in the next 100 years if our trajectory remains consistent with the model described in the Meadows report.
To the 60% extinction of vertebrates in forty years, we must add that today farm animals make up more than 90% of the biomass of non-human mammals, under the combined effect of the development of industrial agriculture and the decline of wild animals. mammals. This percentage in itself is a symbol of the replacement of natural biomass by another, determined and managed by man. This “reworking” of biodiversity also reinforces conversion of forests into agricultural landdriven by growing demand for soybeans for industrial cultivation. In the Amazon, the mutation proceeds in two stages (loss of vegetation cover, then loss of soil fertility), described by Sandra Lavorel: the stability of the Amazonian forest is provided by the phenomenon of self-maintenance of its moisture with the participation of trees. After destructive deforestation, the former forest area becomes an arid zone, subject to loss of fertility, which gradually turns it into a savannah. Thus, this process represents a double ecological disaster: the loss of one of the “green lungs” of the planet, to which is added a huge reservoir of biodiversity. The trend towards deforestation will be exacerbated by the introduction of false technological solutions, such as the development of agrofuels or plant-based packaging, which will compete with food production and require the commissioning of new agricultural land, always occupied in forest areas. When compensation is introduced, as in France, where the area of forests is increasing, these are areas with only one or two species of trees, intended for quick “turning around”, but unfavorable for the richness of the habitat.
There are many other factors affecting biodiversity: “Overhunt” on wild animals kills 22 million annually in France, a third of which are endangered, despite an international agreement on the protection of species signed by France. Soil artificiality concerns every ten years an area equivalent to a French department, which cannot be reclaimed less due to technical impossibility than the staggering costs associated with restoration. We have already mentioned Pollutionwhich is not limited to the spread of pesticides, but also the spread of microparticles of human origin. Disappearance of wetlandsin addition to its important role in the qualitative and quantitative regulation of water, it is also a cause of habitat loss for species.
As Audrey notes, the best reason to strive to protect biodiversity is that we are part of it: we see it every day in the benefits that nature brings to us, not only in terms of photosynthesis, without which we would be carbon-suffocated or crushed. heat, temperature and water regulation, food production, new sources for drug production, and many other unexpected benefits, but also for reasons of psychological balance. Sandra Lavorel does not support estimating benefits solely in dollars or euros, unless it involves using the language of decision makers to balance benefits and costs for each measure: how much the technical solutions for wastewater compensation will cost. wastewater treatment plants, loss of wetlands or – through agricultural land restoration measures – compensation to achieve the stated goal of zero land acquisition by 2050?
In many cultures where the culture of the West has not yet prevailed, man’s relationship to nature is quite different: it is this idea of belonging to nature, or even of responsibility for the integrity of nature, that should be reintroduced into our thoughts. . Western societies only think about changing nature for their own benefit (an example of genetic manipulation and GMOs) or privatizing the living as well as other resources that should be considered as common goods. But, under the pressure of associations, there is a recognition of the right of Nature to self-development, accompanied by a search for solutions that hardly allow us to consider the “technocentric” approach of the living. Audrey Boly also questions Sandra Lavorel about the UN platform that is to biodiversity what the IPCC is to climate, ITPES. The recommendations of his presentations are reminiscent of the solutions mentioned in previous podcasts such as agroecology (Marc Dufumier) presented in the joint IPCC/ITPES report as an important contribution to both biodiversity and climate, the ecosystem approach to fisheries (Philip Cury) and better governance freshwater resources (Florence Habets). With regard to the goal of securing 30% of the maritime domain, Sandra Lavorel expresses her skepticism, even if in terms of surfaces the goal is within our reach. Because the areas chosen for consecration are of the least economic interest, and the measure will prevent neither overfishing nor ocean mining, an ecological disaster that would completely defeat the purpose of the fish ecosystem.
At the end of the interview, various points are randomly mentioned: from a point of view, which is certainly not the point of view of the herders, it is desirable to improve biodiversity through the reintroduction of large predator species (wolf, bear, etc.), to completely change the breeding methods so that they use fewer artificial molecules (antibiotics) to further regulate hunting practices. The COVID crisis is an illustration of the spread of epidemics due to the loss of biodiversity and natural habitats. There are all the reasons that should lead to a change in the economic paradigm, and, the scientist concludes, there is no salvation without this change.