Planetary boundaries are an important conceptual framework. These nine fundamental processes, each with a set of thresholds, represent a measure of the planet’s habitability. To celebrate Earth Day, this article explains the current status of each of these boundaries.

The nine planetary boundaries

Concern about the use of the planet’s resources led to the establishment of Earth Day and the concept of the planetary boundaries. These were proposed in 2009 by a group of scientists led by Johan Rockström and Will Steffen. The main objectives of this system are to assess the state of the planet and to take appropriate measures to reverse or prevent the most damaging effects.

Climate change

This limit, perhaps the best known, was exceeded in the 1990s. Greenhouse gas emissions (GHG), which have been increasing since the beginning of the Industrial Revolution, have been the main cause of this.

They have already caused a temperature rise of 1.1°C, but this could rise to 4°C, which would increase the frequency and strength of weather phenomena. Climate change is undoubtedly a core issue, as it affects the entire planet, which highlights the importance of extracting GHGs from the atmosphere to benefit the environment.

Stratospheric ozone depletion

This limit is in the safe zone. Although it was under threat in the late 1990s, it has now stabilised and recovered. This is due to the ban of the use of CFC products. If this layer were to be lost, the consequences would be very serious. For example, cases of skin cancer would increase considerably.

Land system change

This indicator is affected by deforestation and the destruction of natural habitats. Much of the earth’s land surface is used for agriculture. This helps to feed our planet, but leads to losses that affect biodiversity. The safe limit was exceeded in the mid-2000s.

Freshwater consumption

Freshwater consumption still remains in the safe zone. However, it is moving dangerously close to the risk zone. The planet contains only 2.5% of freshwater, so proper management is essential. Agriculture is again one of the factors that can worsen this indicator.

Nitrogen and phosphorus flows to the biosphere and oceans

Another frontier that has already been crossed (in 2009). The phosphorus and nitrogen cycle is one of the most important biochemical flows. Phosphorus is the most harmful, as it is extracted from the atmosphere to make fertilisers. As these chemical elements are used intensively, their natural behaviour has been altered.

Biodiversity

The limit for biodiversity erosion was also exceeded in 2009. Today, more than one million species are threatened with extinction. As a result, our ecosystems are becoming increasingly fragile.

In fact, many researchers go further and claim that the planet is in the midst of the sixth mass extinction in its history. If so, this would lead to irreversible environmental changes.

Atmospheric Aerosol Loading

This is an unquantified limit. It requires the knowledge of the concentration of particles in the entire atmosphere, which is impossible. However, if pollutant gases increase, air quality is affected, which is particularly noticeable in the world’s most populated cities.

Chemical pollution

Chemical pollution has reached its safe limit in 2022. The use of chemicals has increased steadily since the mid-20th century. They reach almost all ecosystems and cause serious damage. Examples of toxic compounds include plastics, heavy metals and hydrocarbons. When they enter the food chain, they find their way back to humans with serious health consequences.

Ocean acidification

The line has not been crossed, but it is close. Oceans with high acidity absorb less carbon dioxide. This gas has a major impact on the greenhouse effect. In addition, much marine life is affected, especially coral reefs. This in turn disrupts food chains, which can lead to extinction.

Earth’s life support systems

These indicators act as both boundaries and life support systems. Each plays a fundamental role in the habitability of the planet. To alter all of them would be a catastrophe with unforeseeable consequences. For this reason, appropriate measures must be taken to avoid reaching a point of no return.

Four of the nine planetary boundaries have already been exceeded. Of these, two have already reached high risk. Fortunately, it is still possible to reverse their status and keep them safe. Undoubtedly, digital solutions are a key contribution to achieving this goal.

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