A 6th planetary limit has just been crossed, there are only 3 left!

At the very beginning of the 1970s, a report published by researchers from the Massachusetts Institute of Technology (MIT, United States) took stock, for the first time, of the impact of human activity on our Earth. The now infamous Meadows report warned: to continue on the path of ever greater consumption of our planet’s resources would lead us into the wall. A wall erected somewhere on the way to our XXI^and century. A wall that would prevent us from having free access to natural resources. The result is a dramatic deterioration in our living conditions. Which could even lead to disappearance of our civilization.

More than a wall, the Meadows report thus introduced, 50 years ago already, the concept of planetary limits. However, since then, our consumption of resources has continued to increase. So much so that before 2022, four of these planetary boundaries – more clearly defined by scientists from 2009 and more or less linked to each other – had already been crossed: that relating to the change in land use, that touching theintegrity of the biodiversitythat of the disruption of the cycles of the phosphorus and of thenitrogen and that of climate change. In January of this year, researchers from the Stockholm Resilience Center (SRC, Sweden) announced that a fifth limit had just been exceeded: that relating to the chemical pollution.

Today, the same team is back to tell us a bad new moreover. A sixth planetary limit — out of nine in total — has just been crossed. The one that touches on the cycle ofpure water. And this even though part of France is experiencing a drought period worrying and that a quarter of the world’s population does not have access to drinking water.

“Green Water” in the red zone

Why this “failover” suddenly in the red zone? Because the researchers have, for the first time, worked on what they call “green water”. The concept was developed by researchers at the Stockholm International Water Institute (Siwi, Sweden). While ” I’blue water » corresponds to that from precipitationand that human activities withdraw from natural reservoirs, the concept “green water”, enriches it with evaporation and soil moisture. In other words, water available to plants.

“Water is the blood of the biosphere . But our activities profoundly modify its cycle. This is now affecting the health of the entire Planet”explains Lan Wang-Erlandsson, lead author of the SRC study, in a press release from Siwi. The work carried out by the researchers shows that disturbances in the water cycle sweet are today such that there is a real risk ofcollapse ecosystems.

The survival of the Amazon rainforest, for example, is highly dependent on soil moisture. In addition to deforestation, a drop in this humidity — due to global warming — now directly threatens entire regions of this precious green expanse. There is reason to fear that the Amazon will reach a point of no return… and turn into savannah!

” These processes can be very difficult to stop once they have started. It is of utmost importance that we reverse this trend“, conclude the researchers. Especially since the problem does not stop at the tropical forest Amazonian. It affects the whole planet. Soil moisture now changes from boreal forests to the tropicsthrough farmland and temperate forests.

A new planetary boundary has just been crossed

A few years ago, researchers set some planetary boundaries. Thresholds not to be exceeded if we hope to maintain the good conditions in which life has developed on Earth. Some have already been crossed. And today, one more: that relating to the chemical pollution .

Article of Nathalie Mayerpublished on 20/01/2022

plastics, pesticidespaintings, antibiotics , medications. Today there are something like 350,000 different types of chemical products manufactured on the market. And according to researchers from Stockholm Resilience Center (Sweden), their production has multiplied by 50 since the beginning of the 1950s. It should even triple again by 2050.

The trouble is that volumes Not inconsiderable of these chemicals end up polluting nature every year. At a pace that researchers now describe as incompatible with the idea of ​​remaining “in a safe operating space for humanity”. We would thus have crossed what researchers call a planetary boundary.

Remember that the notion of planetary limit was defined in 2009. The researchers then set nine. They make it possible to delimit the remarkably stable state in which the Earth has settled since thedawnof our civilization. That is about 10,000 years ago. If our activities are still confined below some of them, such as that concerning the use ofpure water , some have already been overcome, such as that relating to the change in land use. The limit linked to chemical pollution still remained to be quantified.

The circular economy solution

It is now done. And the researchers’ results are not reassuring. There are indeed many ways in which manufactured chemicals in general and plasticsin particular can have negative effects on our environment. Throughout the production chain, from mining to waste management. Some of these products have even been found in Antarctica . And they can be extremely persistent.

The researchers also note that these chemicals can also affect other planetary boundaries. When resorting to fossil fuels to produce them or that the microplastics come to pollute the fresh water reserves, for example. And even though scientists believe that the speed at which these products appear today far exceeds the ability of governments both to assess the risks and to control potential problems, they call for the establishment “a ceiling on the production and discharge of chemicals”.

Among the most striking examples, that of plastic whose mass total on our planet is now double that… of all the mammalsalive! And we know that not only 80% of these plastics remain in the environment, but that in addition, their degradation produces new combinations which could represent as yet unsuspected environmental risks.

As a solution, the researchers evoke that of the circular economy. The idea, on the one hand, of designing products for their recycling . So that they can be reused and not wasted. The idea, on the other hand, of better assessing safety and sustainabilityof these products throughout their life in the Earth system.