Six ecological thresholds have now been exceeded, according to a study published on September 13, 2023 by around thirty researchers. The cause, in particular, is the exploitation of natural resources by humanity.
Climate change continues and a sixth measure, which concerns the fresh water cycle, has been reached. This is divided into two entities: blue water and green water. Green water, that which plants and vegetables absorb, and which returns to the atmosphere, was already announced as outdated last year in a study. This time, it is blue water, that which flows in rivers to the sea or which is collected in lakes and groundwater, which is threatened, according to a new study.
Humanity has just surpassed this last limit. It is in the process of exhausting it: lakes and rivers dry up in the spring, trees lose their leaves during the summer and fields of sunflowers no longer germinate.
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This is the consequence of several decades of public policies which have led to this overrun. First, so that blue water stops causing flooding. Rivers have been rectified, their trajectory modified so that they flow more quickly into the seas and oceans. Then, as there were fewer floods, we eliminated the floodplains, these wetlands along the banks of watercourses which made it possible to fill the underground reserves. Instead, we put ever-larger cornfields, which required removing trees and hedges almost everywhere, which allowed the blue water to seep into the soil and stay there.
Other planetary boundaries are already exceeded
In 2015, three limits, in other words alert thresholds, had been crossed, four in 2016, six in 2023. Climate change, erosion of biodiversity (species disappearing), chemical pollution: all limits are nevertheless necessary to keep the planet in a livable state. Only the ozone layer, the ninth boundary, continues to recover.
For the ozone layer, good political decisions were made by banning products that destroyed it. So why not act for others, for blue water, for example, an essential resource for the Earth and without which nothing is possible. Scientists say it is still possible to return below these alert thresholds: by closing the tap on the waste produced and the exploitation of raw materials and by having the political courage to set limits.