The urgent need to reduce our footprints within planetary boundaries

Understanding planetary boundaries to take effective action

With the Nos Gestes Climat calculator, measuring your carbon footprint and your water footprint helps you better understand the impact of your lifestyle choices. However, these footprints represent only part of the environmental challenges we face.

Indeed, planetary boundaries are gaining increasing attention and for the right reasons! These critical limits, defined by scientists, preserve the delicate balance needed for the proper functioning of our planet. They help us understand global issues such as biodiversity conservation, water cycle stability and climate regulation. Today, six of these nine boundaries have already been crossed and a seventh is close by. This alarming reality reflects a consumption and production model that directly threatens the conditions necessary for life on Earth.

Our individual footprints alone are not enough. They must be part of a collective approach to respect these ecological limits and support the resilience of our planet.

What are planetary boundaries?

Defined in 2009 by a team of 28 international researchers led by Johan Rockström at the Stockholm Resilience Centre, the nine planetary boundaries ¹ provide a wide perspective of the major environmental challenges humanity faces today. These boundaries are designed to maintain the balance and stability of the Earth's systems.

These boundaries include climate, biodiversity, nitrogen and phosphorus cycles, land use, ocean acidification, freshwater use, forests, stratospheric ozone depletion, atmospheric aerosol loading and the introduction of novel entities into the biosphere.

Scientists identified these nine planetary boundaries, also known as ecological tipping points, to anticipate risks and prevent crossing limits that could irreversibly destabilize the environment. Each exceedance increases the risk of major disruptions to ecosystems and living beings.

These boundaries are now used as an analysis and decision-making tool by international institutions such as the United Nations and the European Commission. They connect global environmental issues and highlight the need for action before we reach critical tipping points.

Currently, six boundaries have already been breached, and a seventh is nearing its limit. This shows the urgency of taking action and identifying the most effective levers to reverse this trend.

The nine planetary boundaries are:

1. Climate change: the increase in greenhouse gases, such as carbon dioxide (CO2), disrupts the Earth's climate balance. This leads to global temperature rises, ecosystem instability and extreme weather events.
2. Biodiversity loss: the rapid extinction of animal and plant species reduces ecosystem resilience, making them more vulnerable to disruptions and compromising the essential services they provide to the planet.
3. Disruptions to nitrogen and phosphorus cycles: intensive agriculture and excessive fertilizer use cause severe water and soil pollution, leading to dead zones in oceans and freshwater systems.
4. Land-use change: the destruction of forests, wetlands, and other natural habitats for agriculture or urbanization reduces biodiversity and diminishes the ability of soils to store carbon.
5. Ocean acidification: the oceans absorb significant amounts of atmospheric carbon dioxide, lowering their pH. This threatens marine life, particularly shell-forming organisms, and reduces the ocean's ability to act as a carbon sink.
6. Freshwater use and cycle disruption: the overexploitation of freshwater resources, including rivers, groundwater, and soil moisture, threatens aquatic ecosystems and reduces water availability for humans and wildlife.
7. Stratospheric ozone depletion: the thinning of the ozone layer in the stratosphere is primarily caused by substances such as chlorofluorocarbons (CFCs), used in refrigeration, air conditioning, and aerosol sprays. Hydrochlorofluorocarbons (HCFCs), developed as CFC replacements, also contribute. Other compounds, including halons (fire extinguishers), carbon tetrachloride (industrial solvents), and methyl bromide (agricultural fumigation), further exacerbate this issue, increasing exposure to harmful UV radiation.
8. Increase in atmospheric aerosols: the rise in airborne particulates affects the climate by altering temperatures and precipitation patterns, influencing weather systems and human health.
9. Introduction of novel entities into the biosphere: microplastics, chemical pollutants, endocrine disruptors, radioactive materials, these human-made substances disrupt ecosystems and accumulate in worrying ways.

Source ²

How many planetary boundaries have been crossed?

In 2025, six out of the nine identified planetary boundaries have already been crossed.

In 2009, when the concept was first introduced, three out of the seven defined boundaries had already been crossed. By 2015, a fourth limit was exceeded. More recently, in 2023, after the addition of two new boundaries, we now observe that six boundaries have been crossed, highlighting a troubling trend.

Crossing these boundaries means that we are entering a zone of increased risk, where ecosystem resilience is compromised and the balance of the Earth systems is under threat. Each transgression raises the likelihood of abrupt or irreversible environmental changes, endangering life on Earth. Moreover, these boundaries are interconnected and interdependent, meaning that breaching one can influence others and amplify environmental disruptions.

These transgressions increase the probability of reaching tipping points, which are safe limits beyond which a system undergoes drastic and often irreversible changes. For example, the melting of Arctic ice could reach a point where positive feedback loops accelerate ice loss, altering ocean currents and climate systems. Similarly, massive deforestation could lead to the collapse of entire ecosystems causing biodiversity loss and disrupting biogeochemical cycles.

Source ¹

The planetary boundaries that have been crossed

Climate change

The climate boundary is defined by the concentration of carbon dioxide (CO2) in the atmosphere. Historically, this concentration was around 280 parts per million (ppm) during the pre-industrial era. Scientists estimate that a safe limit is between 350 and 450 ppm. Today, atmospheric CO2 levels have reached approximately 420 ppm ⁽³⁾, reflecting the direct impact of human activities, particularly the burning of fossil fuels. This situation accelerates climate change. For instance, the irreversible melting of Arctic ice and Himalayan glaciers would significantly raise sea levels, alter coastal ecosystems, and threaten millions of people living in coastal areas. Additionally, glacier loss disrupts freshwater cycles, affecting water availability for agriculture and human consumption.

Biodiversity loss

This boundary measures species extinction rates and has been severely crossed with 1 million species of animals and plants currently at risk of extinction. The current extinction rate is 10 to 100 times higher than the average over the past 10 million years ⁴. This alarming reality is driven by human activities including deforestation, intensive agriculture, pollution, and climate change. Each species loss weakens ecosystems, reducing their resilience and ability to provide essential ecosystem services.

Disruptions to nitrogen and phosphorus cycles

The nitrogen and phosphorus cycles are essential for soil fertility and agricultural productivity, but they are severely disrupted. The overuse of fertilizers in industrial agriculture has led to massive soil and water pollution, causing eutrophication in aquatic ecosystems ⁵.

Eutrophication refers to an excessive proliferation of algae and microorganisms in water bodies. These algae consume dissolved oxygen, leading to dead zones where marine life cannot survive. Eutrophication directly threatens aquatic biodiversity and can also pose health risks through contaminated drinking water or toxic algae blooms.

Land-use change

Deforestation and agricultural expansion, often at the expense of tropical and boreal forests, are dramatically altering landscapes. These critical ecosystems now cover only 62% of their original area, far below the estimated threshold of 75% needed to maintain ecological balance ⁶.

Forests play a fundamental role in regulating our planet's functions. They are not just carbon sinks, absorbing significant amounts of CO2, but also regulate water cycles, stabilize soils, and provide habitats for countless species. Trees form a powerful living network, filtering air, storing water and protecting biodiversity.

When grouped into forests, trees act as natural barriers against climate change and ecological disasters. The loss of these habitats directly threatens biodiversity and reduces Earth's ability to buffer environmental shocks. Protecting forests means safeguarding life in all its forms and ensuring the stability of our Earth system.

Introduction of novel entities into the biosphere

This newly identified boundary concerns chemical pollutants, plastics, and synthetic materials introduced by humans into ecosystems. Since 1950, the production of these substances has increased by fifty, and their global dispersion is now uncontrollable ⁷.

Few of these substances have been fully assessed for their impact on human health and the environment, increasing risks associated with their accumulation.

Freshwater use: the latest boundary to be crossed

Freshwater management has become critical marking the recent transgression of another planetary boundary. While global blue water withdrawals (from lakes, rivers and groundwater) remain below critical limits at a global scale, increasing localized stress is destabilizing aquatic ecosystems and limiting their ability to provide essential services.

Additionally, green water (soil moisture) is increasingly disrupted with some regions experiencing droughts and others facing oversaturation. These imbalances affect agricultural productivity, exacerbate food insecurity and reduce ecosystems’ ability to act as carbon sinks or provide habitats for biodiversity ⁸.

Planetary boundaries vs. Earth Overshoot Day: what's the difference?**

Often confused with planetary boundaries, Earth Overshoot Day is a date when humanity has used more resources than the Earth can regenerate in a year. In 2024, this date was reached on August 1st, setting another concerning record.

This indicator, published annually by the Global Footprint Network, shows an accelerating overconsumption: in 2024, we would need 1.7 Earths to meet our consumption demands.

Source ⁹

Unlike this annual measurement, planetary boundaries assess global systemic processes and include precautionary limits to prevent irreversible tipping points.

These two concepts complete each other: Earth Overshoot Day highlights immediate overconsumption while planetary boundaries focus on long-term ecosystem stability.

Reducing our footprints to respect planetary boundaries

Every choice we make leaves a footprint. Our carbon footprint and water footprint, while individual indicators, reflect collective pressures on planetary boundaries. Reducing these footprints means taking direct action on global challenges such as climate change, water scarcity and biodiversity loss.

Carbon footprint: a high-impact measure

Carbon is central to planetary boundary concerns. Although all boundaries are important, climate change is unique in its wide influence on other ecological processes. Greenhouse gas emissions, measured through carbon footprint assessments, directly impact multiple Earth system processes ¹⁰. Increasing CO2 levels contribute to global warming, ocean acidification and habitat destruction.

By measuring your carbon footprint and adopting low-carbon lifestyles such as choosing sustainable transportation, reducing meat consumption and minimizing consumption of goods you can help slow these trends.

Water footprint: Preserving a fragile resource

Water is indispensable yet increasingly scarce, closely linked to several planetary boundaries, including freshwater use, biodiversity loss, and climate change.

On average, an individual indirectly consumes 4,000 to 9,000 liters of water per day, primarily through food and product consumption. Reducing your water footprint by adopting plant-based diets, choosing responsible fashion and minimizing waste helps protect freshwater resources and stabilize hydrological cycles.

Measuring your footprints to take effective action

Reducing your carbon and water footprints is a *great starting point for respecting planetary boundaries. By measuring them with the Nos Gestes Climat calculator, you can understand and take action. These insights help prioritize impactful lifestyle changes and contribute to preserving our planet.