Even if the concept of the 9 planetary boundaries still arouses debate among experts, it is more and more commonly taken up by scientists. It defines tolerance thresholds that humanity must not cross in order to avoid too sudden changes to the environment and the stability of our ecosystems.
Even if climate inaction remains glaring, it’s not just the weather who should mobilize us! The reduction of greenhouse gas emissions and the fight against global warming are only one aspect of the actions to be taken to relieve the planet so that it remains habitable. There is good other areas in which the Earth is abused by human predation: biodiversity, plastic pollution, fresh water, land use…
What is a planetary boundary?
It is in this state of mind that in 2009, a team of 29 scientists from Stockholm Resilience Center studied the processes that regulate the stability and resilience of the Earth system. They started from the idea that, for more than 10,000 yearsthroughout the Holocene, the Earth remained in a stable state, and that if certain limits were to be crossed, we could witness a change of state of the planetary ecosystem.
They then proposed a quantitative measure of the 9 planetary boundaries within which humanity can continue to grow and prosper. These planetary boundaries therefore answer this complex question: “ up to what thresholds the Earth system will be able to absorb the pressures of Man without compromising living conditions of the human species? “.
The 9 planetary boundaries have been the subject of a fascinating documentary, available on Netflix, presented by David Attenborough and titled Our planet has its limits: The science alert.
The 75-minute film explores the critical thresholds that must not be crossed if we want to ensure both the stability of the planet and the future of humanity. It offers the solutions we urgently need to put in place to protect the mechanisms of the Earth system that are essential to life.
A concept that is less and less debated
The concept of the 9 planetary boundaries still arouses a lot of debate among scientists, but it has been recognized and adopted at many national and European levels, and even internationally with the UN.
In France, it is more and more regularly taken up by authors and experts such as Arthur Keller, Pablo Servigne Where Aurelien Barbeauto show that the fight against global warming is far from being the only threat hanging over the Earth.
Thus, in 2022 alone, two of the 9 planetary boundaries have been crossed, according to the report of the Stockholm study group published in the reference journal Nature (in English). This is the limit of chemical and plastic pollution and that of the freshwater cycle.
Only 3 of the 9 planetary boundaries have not been exceeded
Of the 9 established planetary boundaries, six of them have already been crossed in 2022:
- Climate change
- The integrity of the biosphere (erosion of biodiversity)
- Biogeochemical disturbances (nitrogen and phosphorus cycles)
- Changes in terrestrial ecosystems (land use)
- Pollution by new substances (chemicals, plastics, etc.)
- The use of fresh water
Of the 9 planetary limits that humanity must not cross, on a global scale, to avoid too drastic changes in our environment, there remains today only three limitswhich are, according to the Stockholm expert group, difficult to measure precisely :
- Ocean acidification
- The reduction of the stratospheric ozone layer
- The concentration of aerosols in the atmosphere
To cross a limit is to take the risk of a “snowball” effect of irreversible transformations, which will upset the balance of the planet and the viability of the environment.
Further proof of the urgency of acting to protect the Earth by drastically reducing the resources let’s draw from it. Can we collectively give ourselves the means to ensure the stability of our ecosystem? ?