Six out of nine. It’s the sad number of planetary boundaries which were exceeded, first in 2015, then in 2022. Established in 2009 by an international team of 26 researchers from scientific journals Nature And Ecology and Society, these nine thresholds not to be exceeded on a global scale should make it possible to assess the overall impact of human activities on the planet. Fourteen years later, the result is clear: if humanity continues on this path, the habitability of the Earth by men and women could well be called into question.
“It was when I read the Meadows report that I realized that it was not just a climate problem, but that we had a global problem of planetary boundaries,” recalls Audrey Boehly, journalist scientist and author of the podcast and the eponymous book Last limits.
Published in 1972 by researchers at the Massachusetts Institute of Technology (MIT), led by Dennis Meadows, The limits to growth is the bedside book of many researchers. And for good reason: it models different scenarios through which, depending on the trajectories of greenhouse gas emissions and consumption uses, it is possible to understand the possible worlds of tomorrow. More or less enviable depending on the trajectory chosen.
A possible collapse of the system
Population, industrial and agricultural production, pollution, state of non-renewable resources… The planetary limits are multiple and they affect all sectors of development of thermo-industrial civilisation. “What is clear is that if we continue to grow, we will arrive at a collapse of the system [d’ici 2100]. Either because we will be overwhelmed by our pollution, including CO2. Either because we risk finding ourselves facing a wall due to the use of non-renewable resources, such as oil, which today guarantee the continuation of this growth,” explains Audrey Boehly. A real headlong rush, in short.
But what are, concretely, the main issues related to going beyond planetary limits? What are the risks of crossing the tipping points associated with these limits? Are their consequences reversible? On the occasion of Earth Day on April 22, with the aim of raising awareness of the impact of human activities on the climate, but also on soils, freshwater resources, the biosphere and biochemical cycles , 20 minutes returns to the concept of planetary limits with, facing the camera, journalist Audrey Boehly.