"If we don't change, it will happen again".

"Totally predictable". This is how Serge Morand* characterizes the Covid-19 pandemic. And that's good news: it means we know how to limit the risk of future epidemics. future epidemics. Explanations from the ecologist and evolutionary biologist at theInstitut des sciences de l'évolution de Montpellier.

Savannah landscape near Tontouta. Savannah is a substitute plant formation, as it is often the result of deforestation or clearing, and is maintained by fire. IRD - Jean-Christophe Gay

How do you explain the direct link between the decline in biodiversity and the increase in epidemics?
The decline in biodiversity is often seen as an ecological crisis, but in reality it's also a health crisis. In fact, when biodiversity is high, there is a great diversity of potential pathogens such as viruses, but they circulate at a low level, which means that they are transmitted in a moderately efficient way and are unlikely to end up infecting humans. On the other hand, when biodiversity falls, contact between wildlife viruses and humans increases, raising the risk of disease transmission.

How do these contacts occur?
The decline in biodiversity is attributable to human activities: urbanization, resource exploitation and, above all, industrial agriculture and livestock farming are responsible for deforestation and the destruction of natural habitats. Predators can disappear, upsetting the balance of ecosystems and encouraging the emergence of pathogens. But above all, these activities bring together species that would never have crossed paths in the wild: wild animals and domesticated or farmed animals. We are thus creating new interfaces conducive to the spread of viruses. An emblematic example is the Nipah virus that struck Malaysia in 1998. It appeared when bats, driven out of their habitat by palm oil exploitation, came into contact with pig farms which, once infected, were consumed by humans. As for the coronavirus, we are now certain that it too comes from a bat, but the so-called "intermediate" host - the one that enabled the virus to acquire the genetic determinants needed to infect man - is not yet known.

Are there more and more new epidemics?
Yes, on a global scale, the number of epidemics has increased more than tenfold between 1940 and today. Not only are there more of them, but above all they are becoming globalized and no longer confined to the country where they first emerged. Since the 1960s, the pace of change has accelerated dramatically. The cause: the intensification of trade. In fifty years, air traffic has increased by 1,300%!

At the same time, tourism soared by 5,600%. Covid-19 is a disease spread by international travel. This pandemic was totally predictable: all the conditions were in place for an emerging infectious disease of this type to spread rapidly across the planet.

If we could predict this pandemic, how could we guard against the next?
Our entire approach to ecosystems needs to change, starting with our global agri-food system. Intensive livestock farming is a case in point: the total weight of cattle on the planet is greater than the total weight of human beings! To feed all these animals, huge areas of land are deforested to produce soya or corn, destroying natural habitats and encouraging intensive monocultures. It's precisely these unifunctional landscapes that need to be abandoned in favor of non-specialized mosaic environments. We need to recreate multifunctional territories. We need to move towards a more territorialized agro-ecology and agronomy, which also implies restoring autonomy to territories. To achieve this, the entire Common Agricultural Policy needs to be overhauled, starting with a renegotiation of the debt owed by farmers, in order to move towards agro-ecology.

So we need to radically transform our agri-food system?
Yes, but not only that. We need to deglobalize our economies, reduce mobility and relocalize economic activities. We need to move towards less tourism and more sustainable tourism, and we need to consume locally. The coronavirus crisis has created a real awareness of the need for change, and it's a really interesting time for all those involved in agronomy, forest ecology, agroecology, the local and circular economy. It's a real challenge for the new generations of students, and we need to give them a free hand to take it up and trust them. Everyone stands to gain from these changes: biodiversity, the climate, farmers, but also our health and well-being. In any case, we have no choice but to make this shift: if we don't change, it will inevitably happen again.

*Isem (UM - CNRS - IRD - EPHE)