Planetary boundaries are a system used to describe the limits of human activities on Earth. If these limits are crossed, the environment may no longer be able to maintain balance. This could cause the Earth system to leave the Holocene, a stable period in Earth's history during which human societies developed.

There are nine planetary boundaries: climate change, ocean acidification, stratospheric ozone depletion, changes in nitrogen and phosphorus cycles, excessive use of freshwater, land use changes, loss of biodiversity, chemical pollution, and atmospheric aerosol loading.

This framework is based on scientific evidence showing that human actions, especially those of industrialized societies since the Industrial Revolution, have become the main cause of global environmental changes. According to the framework, crossing one or more planetary boundaries could lead to harmful or catastrophic effects because it may trigger sudden, large-scale environmental changes.

The framework suggests that human societies have thrived during the Holocene’s stable conditions. As long as Earth system boundaries are not crossed, they define a "safe zone" for human societies. Supporters of the framework argue that returning to these natural conditions is better than trying to create a more favorable climate through human technology. The concept does not explain how humans have changed ecosystems to suit their needs. The Holocene conditions considered safe by the framework do not include large-scale industrial farming, which raises questions about how to feed modern populations.

The idea of planetary boundaries has influenced international groups, including the United Nations Conference on Sustainable Development, governments, organizations, and scientists. The framework includes nine processes linked to global environmental changes. In 2009, scientists identified three boundaries already crossed: biodiversity loss, climate change, and nitrogen cycle changes. Other boundaries were close to being crossed.

In 2015, scientists updated the framework, adding new co-authors and models. They found four boundaries had been crossed: climate change, loss of biodiversity, land use changes, and altered biogeochemical cycles (phosphorus and nitrogen). They renamed the "loss of biodiversity" boundary to "change in biosphere integrity" to highlight that both species numbers and the overall function of ecosystems are important for Earth’s stability. The "chemical pollution" boundary was renamed "introduction of novel entities" to include a broader range of human-made materials that disrupt Earth’s systems.

In 2022, scientists concluded that "introduction of novel entities" was the fifth crossed boundary. In 2023, freshwater use was identified as the sixth crossed boundary. In 2025, ocean acidification was confirmed as the seventh crossed boundary.

Framework overview and principles

The Planetary Boundaries framework explains that keeping Earth's stability during the Holocene is important for long-term human progress in society and the economy. This framework helps people understand global sustainability by showing how Earth's systems work on a worldwide scale and over long periods of time.

The framework lists nine "planetary life support systems" that are needed to keep Earth in a stable state. It also tries to measure how far some of these systems have changed. Scientists set limits to create a "safe space for human development," which is better than older methods that focused only on reducing harm to the planet.

The framework is based on scientific research showing that human activities, especially those from industrialized societies since the Industrial Revolution, are the main cause of global environmental changes. According to the framework, crossing one or more of these boundaries could lead to harmful or dangerous effects because it might cause sudden and unpredictable changes in Earth's systems. The framework includes nine processes related to global changes. In 2009, two of these boundaries were already crossed, and others were close to being crossed. Later studies showed that three boundaries—climate change, loss of biodiversity, and changes in chemical cycles—had likely been crossed.

Scientists explained that breaking these boundaries increases the risk of major problems in Earth's natural systems, which could harm human well-being. While they acknowledged that some details are not fully understood, they warned that crossing these boundaries might cause feedbacks that make it harder to return to safe conditions. The boundaries are initial estimates with many uncertainties and gaps in knowledge that are not yet fully understood.

The Planetary Boundaries framework provides a new way to think about how societies should govern and manage resources. It moves away from focusing only on reducing harm in specific areas, toward creating a "safe space for human development" globally. These boundaries define the "planetary playing field" for humans to avoid large-scale environmental changes.

The framework was created in 2009 by a group of Earth system and environmental scientists led by Johan Rockström from the Stockholm Resilience Centre and Will Steffen from the Australian National University. They worked with 26 other leading scientists, including Nobel Prize winner Paul Crutzen, climate scientist James Hansen, oceanographer Katherine Richardson, geographer Diana Liverman, and Hans Joachim Schellnhuber, who advises Germany's leader on climate issues.

Most of these scientists were involved in planning for the Earth System Science Partnership, which later became the international research network Future Earth. Their goal was to define a "safe operating space for humanity" for the scientific community, which is needed for achieving sustainable development.

Nine boundaries

A 2009 study identified nine planetary boundaries with measurements for seven of them. By 2025, measurements were added for eight of these boundaries. These are:

• Climate change: Atmospheric carbon dioxide (CO₂) levels should stay below 350 parts per million (ppm), or the change in Earth’s energy balance (radiative forcing) should not exceed +1 W/m².
• Biosphere integrity: The loss of species should be less than 10 extinctions per million species each year.
• Land system change: No more than 15% of ice-free land should be used for farming.
• Freshwater use: Consumption of water from rivers and lakes should not exceed 4,000 km³ per year.
• Biogeochemical flows: Human activities should not fix more than 35 teragrams (Tg) of nitrogen (N) per year, or add more than 10 times the natural amount of phosphorus (P) to oceans annually.
• Ocean acidification: The ability of seawater to support marine life (aragonite saturation) should remain at least 80% of pre-industrial levels.
• Atmospheric aerosol loading: Scientists have not yet defined a global measurement for this boundary.
• Stratospheric ozone depletion: Ozone levels should not drop by more than 5% from pre-industrial levels (290 Dobson Units).
• Chemical pollution: Introduction of harmful substances into the environment should be limited.

Measurements for these boundaries are based on how Earth’s systems interact. Scientists chose specific variables to track how human actions move Earth away from stable conditions seen during the Holocene era.

Some Earth processes show clear thresholds. For example, during ice ages, CO₂ levels were about 180–200 ppm, but during warmer periods like the Holocene, CO₂ stayed near 280 ppm. To understand what Earth was like with CO₂ over 350 ppm, scientists must look back about 3 million years. Evidence from Earth’s history shows that small changes in variables like CO₂ can cause large, sudden shifts in Earth’s systems.

For some boundaries, it is hard to define exact thresholds because Earth’s systems are complex, and scientific data is incomplete. For example, changes in monsoon patterns may depend on both aerosol levels and freshwater use.

The planetary boundaries framework sets ranges for control variables. These ranges aim to keep Earth in a “safe operating space” similar to the Holocene. The boundary is defined as the lower end of this range. If boundaries are crossed repeatedly, Earth may enter a dangerous state.

Restoring a safe operating space is difficult because human societies often prioritize economic growth over environmental protection. Legal rules can help, but their effectiveness depends on political will.

Understanding Earth’s systems requires studying how environmental processes interact. While planetary boundaries are based on Earth’s natural conditions, scientific discussions about how boundaries relate to each other are often unclear. Clearer definitions could help.

Interactions among planetary boundaries can create both stabilizing and destabilizing effects. For example, crossing the freshwater boundary might reduce the land available for farming, lowering the land use boundary. Similarly, deforestation in the Amazon could reduce water resources in Asia. These interactions shift the focus from Earth’s natural conditions to human needs, such as agricultural land. Scientists warn that crossing any boundary could shrink the safe space for other processes.

Coral reefs and marine ecosystems are also affected. Since 1990, coral calcification (the process of forming calcium carbonate structures) in the Great Barrier Reef has decreased by 14% in less than 20 years. This decline is linked to rising ocean temperatures and lower aragonite saturation. Other stressors, like overfishing and pollution, further harm marine life. Ocean acidification may drastically change the distribution and survival of species that rely on calcium carbonate for shells or skeletons.

In 2012, a scientist proposed a tenth boundary: the annual global production of plant life, which could indicate ecosystem health.

A 2015 study updated the planetary boundaries concept, stating that four boundaries—climate change, biodiversity loss, land use, and biogeochemical cycles—had already been crossed. The study emphasized that climate change and biodiversity loss are central to the framework.

In 2017, some scientists argued that marine systems were not fully represented in the framework. They suggested including seabed changes and ocean circulation patterns.

Later research began to examine planetary boundaries at regional scales.

A 2018 study questioned whether efforts to limit global warming to 2°C above pre-industrial levels, as outlined in the Paris Agreement, would be enough to prevent serious environmental harm. Scientists noted that even with reduced emissions, some risks might remain.

Related concepts

Planetary integrity is also called Earth's life-support systems or ecological integrity. Scholars say planetary integrity must be kept to ensure long-term sustainability. In this context, "integrity" means the health of ecosystems. The idea of planetary integrity is closely connected to the concept of planetary boundaries.

In 1998, an Expert Panel on Ecological Integrity defined ecological integrity as follows: "Ecosystems have integrity when they include their natural parts, like plants, animals, and other living things, and natural processes, such as growth and reproduction, are fully present."

Human activities are causing harm to the environment, which reduces planetary integrity. For example, the loss of biodiversity is threatening ecological health worldwide. The Sustainable Development Goals may help guide efforts to address this loss.

The idea that Earth has limits to how much humans can use its resources has existed for many years. The Planetary Boundaries framework is influenced by the 1972 study The Limits to Growth, which showed how rapid population growth, industrialization, pollution, and resource use could outpace the ability to create new resources. This study was widely criticized, especially by economists and business leaders, and many claimed its predictions were wrong. In 2008, Graham Turner from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) compared the study’s predictions with 30 years of real-world data. While some argue the study’s model is flawed, others say historical data since the 1970s support its main findings. The Limits to Growth explores how the interactions between society, technology, and the economy might limit human progress and create risks of collapse. In contrast, the Planetary Boundaries framework focuses on the natural processes that shape Earth’s systems.

In 1987, Our Common Future was published by the United Nations’ World Commission on Environment and Development. It aimed to connect the ideas of development and environmental protection for future discussions. It introduced the well-known definition of sustainable development: "Development that meets the needs of the present without harming future generations’ ability to meet their own needs."

Another important idea linked to the Planetary Boundaries framework is the Gaia hypothesis. In the 1970s, scientists James Lovelock and Lynn Margulis proposed that all living things and Earth’s non-living parts form a single, self-regulating system. This system can adjust to changes, like how a living organism maintains its temperature. However, this ability has limits. For example, if an organism is exposed to temperatures outside its survival range, it can die. Similarly, Earth may not be able to recover from large changes in critical conditions. In his book The Revenge of Gaia, Lovelock suggests that the destruction of rainforests, biodiversity loss, and human-caused global warming could shift Earth’s systems from balance to a cycle that intensifies problems.

Science shows that humans are crossing planetary boundaries that have protected civilization for 10,000 years. Evidence suggests human activities are overwhelming Earth’s ability to absorb changes. Humans are now the main cause of global changes, leading Earth into a new geological era called the Anthropocene. This means humans are not just changing Earth but also causing its systems to break down, reducing their ability to recover and potentially threatening life on Earth.

The previous geological era, the Holocene, began about 10,000 years ago. It was a stable time with few major changes, allowing human societies to grow and develop agriculture, cities, and trade networks. Scientists, including Rockström et al., argue that the stability of the Holocene should guide efforts to maintain a healthy Earth. They say humans have become so reliant on Earth’s systems that we must use the Holocene’s natural balance as a model for a sustainable future.

Human actions are causing rapid changes in Earth’s systems that support its resilience. For example, species are now going extinct 100 times faster than before, and humans are altering global water flows. Continued human pressure on Earth’s systems could lead to sudden, large-scale, or irreversible changes that affect the planet and human communities.

Reception and debate

The planetary boundary concept is an important idea that should be followed by discussions about how different boundaries are connected and how they relate to other ideas, such as "limits to growth." This new idea shows the danger of reaching certain points where Earth's systems might change suddenly or in unexpected ways. It can help people work together to solve major environmental problems, like climate change.

In 2009, a report was shared with the General Assembly of the Club of Rome in Amsterdam. A shorter version of the report was published in a special edition of the journal Nature in 2009. This edition also included comments from well-known scientists, such as Nobel Prize winner Mario J. Molina and biologist Cristián Samper.

Some experts in development studies have criticized parts of the planetary boundary framework. They worry that it might place unfair limits on countries in the Global South. For example, proposals to protect forests could favor countries in Europe that already used their forests for farming and industry. Meanwhile, countries that have not yet developed are asked to make changes even though they may not have caused much environmental harm.

William Schlesinger, a scientist, questions whether setting thresholds for pollution is a good idea. He believes waiting until we near a limit might allow problems to grow until it is too late. He says that managing pollution based on thresholds, while simple, can let slow and hidden damage continue for a long time.

In a study involving students studying environmental and sustainability topics in 35 countries, researchers found that people around the world have very different views about planetary boundaries.

Subsequent developments

The Doughnut, also called Doughnut economics, is a diagram used to show how to achieve sustainable development. It looks like a doughnut or a lifebelt and combines two ideas: the limits Earth can handle (planetary boundaries) and the needs people must have to live well (social boundaries). The name comes from the shape of the diagram, which is a circle with a hole in the center. The hole shows how many people lack basic needs like healthcare, education, and fairness. The outer edge of the diagram represents the limits of Earth’s resources that must not be exceeded. The diagram was created by economist Kate Raworth in a 2012 Oxfam paper titled A Safe and Just Space for Humanity and further explained in her 2017 book Doughnut Economics: Seven Ways to Think Like a 21st-Century Economist and other papers.

Studies have examined how countries use Earth’s resources compared to planetary boundaries. These studies include Portugal, Sweden, Switzerland, the Netherlands, the European Union, India, many countries in the Belt and Road Initiative, and major global economies. Although the methods used to measure resource use varied, the results show that if wealthier nations’ resource use were extended to the entire world population, it would exceed Earth’s limits.

Human activities related to farming and eating contribute to crossing four of nine planetary boundaries. Excess nutrients (like nitrogen and phosphorus) entering land and water ecosystems are the most significant issue, followed by changes to land use and loss of biodiversity. For biodiversity loss, phosphorus cycles, and land use changes, the risk is in a range of uncertainty (shown as a yellow circle in the diagram). However, the nitrogen boundary linked to farming is more than 200% exceeded, showing a high risk (marked as a red circle). Here, "nutrition" includes food production, trade, and household food preparation. Environmental impacts from eating are not measured globally for three planetary boundaries: freshwater use, air pollution, and thinning of the ozone layer.

Methods that respect Earth’s limits include individual limits on carbon use and laws that set national limits for greenhouse gas emissions. People would have freedom to make choices within these shared limits, as long as they are informed about the collective boundaries.

Usage at international policy level

On March 16, 2012, United Nations Secretary-General Ban Ki-moon supported the idea of planetary boundaries. He shared the main ideas from the report of the High Level Panel on Global Sustainability during a meeting with the UN General Assembly. Ban said, "The Panel's goal is to end poverty, reduce inequality, make economic growth fairer, and make production and consumption more sustainable. This includes fighting climate change and respecting other limits on Earth's environment."

The concept of planetary boundaries was included in the first draft of the agreement from the United Nations Conference on Sustainable Development, which was planned for Rio de Janeiro from June 20 to June 22, 2012. However, the idea was later removed from the final agreement. Some poorer countries were worried that using the concept might slow down efforts to reduce poverty and grow economies. Others believed the idea was too new and needed more time to be tested before being officially accepted by the United Nations.

In 2011, the High Level Panel on Global Sustainability included the idea of planetary boundaries in their work. Their goal was to end poverty, reduce inequality, make growth fairer, and make production and consumption more sustainable while fighting climate change and respecting Earth's limits.

Panel members also discussed concerns about how the idea of planetary boundaries might be used politically. They said the concept is still developing and should be used carefully. Some members noted that the idea could cause disagreements, as it might be seen as a way for wealthier countries to stop poorer countries from following the same development path that caused environmental harm. Many developing countries found this idea unacceptable because they believe it could limit their economic growth.

Despite these concerns, the concept of planetary boundaries is often used in United Nations meetings and reports. For example, Achim Steiner, the head of the United Nations Environment Programme (UNEP), said agriculture must "feed a growing global population without pushing humanity's footprint beyond planetary boundaries." The UNEP Yearbook 2010 also included the idea of planetary boundaries, connecting it to managing ecosystems and environmental governance.

In their 2012 report, "Resilient People, Resilient Planet: A Future Worth Choosing," the High Level Panel on Global Sustainability called for strong global actions, including starting a major scientific effort to improve the connection between science and policy. They said scientists must clearly define terms like "planetary boundaries," "environmental thresholds," and "tipping points."

The idea of planetary boundaries is also used by the European Commission and was mentioned in the European Environment Agency's report, "The European Environment – State and Outlook 2010."