The awareness of the urgency to address environmental problems and climate change increasingly raises the question of what solutions exist for these issues.

It's evident that, being a complex problem, there are no simple solutions. The first problem is understanding how the environmental systems that make up planet Earth work. An environmental system can be defined as the spatial and temporal dimension of an ecosystem (composed of living beings and geological, chemical, and physical components that constitute a whole connected by relationships) and its environment (constituted by its surroundings, such as the atmosphere and climate). Each environmental system is thus defined by its components and relationships, and by its ability to endure over time, adapting and responding to environmental changes. Each environmental system responds to change through a system of positive and negative feedbacks.

Positive feedbacks amplify the effects of change (for example, if a nutrient-rich runoff reaches a lake, the plants present increase in number because they have more available "food"; and the more plants there are (e.g., algae), the more the animals (e.g., shrimp) that eat them increase, creating a growing effect on the quantity and type of organisms present). Negative feedbacks diminish the effects of change. For example, an increase in grass in a pasture attracts new herbivores (e.g., sheep) that eat it, reducing the amount of grass.

The other characteristic of environmental systems is the presence of thresholds or limits that, if exceeded, lead to the "death" of the system and its replacement by another. If too many nutrients reach a lake or a semi-enclosed stretch of sea and the quality of the plants grows too much, these plants, by consuming all their resources (food, technically with the phenomenon of eutrophication), die and consume oxygen. By consuming oxygen, all organisms that depend on that oxygen "can't breathe," die, and, in turn, by dying, consume more oxygen, increasing with a positive feedback the consumption of oxygen (this is called the phenomenon of dystrophy, which leads to an environment with little or no oxygen, technically to the creation of an anoxic environment). The environmental system "dies" and is replaced by a new and different environmental system.

The concept of a threshold, beyond which the system changes, is therefore fundamental. Our planet is changing rapidly, and the only way to prevent the conditions that make our civilization's survival possible is to identify which thresholds we have already crossed and which ones we are still in time not to exceed. To deal with such a complex framework, in 2009, a group of 28 scientists, led by the Swede Johan Rockström, and including Nobel Prize winner Paul Crutzen, proposed a scheme comprising nine "planetary boundaries" related to processes that are fundamental to the resilience of our civilization and that are now threatened by the development of the same.

The nine planetary boundaries are largely on the threshold, either just before or just after. We have to change quickly before we end up in the abyss. And the abyss is not the end of the planet; it is the end of the planet's habitability for our species. We are on a spaceship Earth, which is resilient as a system but fragile in terms of our lives.

Now is the time to roll up our sleeves and start not to "fix" the planet, but to build a society that is consistent with the functioning of ecosystems and does not work against us.

* Ph.D. in Environmental Sciences and External Professor of Environmental Systems and Biomimetics at IUAV University of Venice