(Environmental) Planetary Boundaries: What They Are, & Which Ones We Have Crossed

There’s various concepts that have been developed to measure different aspects of resource depletion, environmental and ecological degradation, and also overall sustainability.

One example is the ecological footprint, and another is carrying capacity.

The concept of the planetary boundaries is a third.

In this guide, we outline what the 9 planetary boundaries identified by scientists are.

We also discuss the status of different boundaries, including which ones we might be close to crossing, and which ones we might have already crossed.


Summary – Planetary Boundaries

What Are The Planetary Boundaries?

Planetary boundaries is a concept developed by scientists

As a concept, planetary boundaries relate to the regulation, in terms of stability and resilience, or the different Earth systems

Said another way – they have global sustainability implications for humanity depending on how close humanity stays inside them, or how far they cross them


Potential Consequences Of Crossing The Boundaries

Staying within the boundaries might contribute to sustainable living for present and future generations

Crossing the boundaries might increase the risk of environmental change that contributes to unsustainable living

Changes might affect the state of the environment and it’s ecological systems and wildlife (whether they are thriving, or heading towards degradation and extinction), the availability of natural resources, and other key factors


Which Boundaries Have Been Crossed At This Point In Time?

As of right now, there are two boundaries that we have crossed  ‘beyond the zone of uncertainty’, and are a ‘high risk’ when looking at the stockholdresilience.org data – those are biochemical flows (of both nitrogen and phosphorus), and biosphere integrity (genetic diversity).

Nitrogen in particular is one of the boundaries that presents the highest risk right now along with generic diversity, and phosphorus slightly behind that

However, undark.org (URL in the resources list) has also put together a good article explaining how advances in processes and technology relating to increased resource production or extraction always have ecological degradation consequences.

What they note is that right now, we are exceeding the safe limit for 4 planetary boundaries – climate change, land system change, biochemical flows and biosphere integrity.


Which Boundaries Are We Potentially Close To Crossing?

There are another two boundaries we have reached the ‘zone of uncertainty’ for and have an ‘increasing risk’ rating – climate change, and land system change


Other Notes

Some boundaries may be more critical to stay within than others, and these boundaries might be referred to as core boundaries

In order to be able to assess or monitor each boundary, there might be control variables that can be tracked for each boundary/earth system process. Having said this, there can also be general factors that impact multiple boundaries, such as human overpopulation as one example

Some sources even identify an exact value or measurement for where a boundary might lie e.g. the climate change boundary might be that atmospheric concentrations of CO2 are at no more than 350ppm


Limitations Of Using Planetary Boundaries As A Concept

Like other sustainability concepts, the planetary boundaries concept may also have limitations in it’s use, and might be used as a starting point for discussion only. It’s not a definitive way to assess different sustainability indicators

Having said that, it is noted that the concept has generated interest in science, policy, and practice


What Is The Planetary Boundaries Concept?

It relates to the regulation and stability of Earth’s systems


[It’s a concept that] presents a set of nine planetary boundaries that are theorised to ‘regulate the stability and resilience of the Earth system’ (stockholmresilience.org)


What Are The Potential Consequences Of Crossing Planetary Boundaries?

Crossing the boundaries could contribute to environmental degradation, and also contribute to unsustainable or undesirable living for humanity


Crossing [the planetary boundaries] ‘increases the risk of generating large-scale abrupt or irreversible environmental changes’ (stockholmresilience.org)


The potential consequences of crossing planetary boundaries are described in a different way by scripps.ucsd.edu:

Transgressing a boundary increases the risk that human activities could inadvertently drive the earth system into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human well-being in many parts of the world, including wealthy countries


What Are The 9 Different Planetary Boundaries? 

You can read in full the 9 planetary boundaries and a description of each of them at stockholmresilience.org

As a summary though, they are:


1. Climate Change

Release of greenhouse gases like CO2 into the atmosphere, leading to Earth’s warming


2. Release of Novel Entities

Emissions of toxic and long-lived substances such as synthetic organic pollutants, heavy metal compounds and radioactive materials


3. Stratospheric Ozone Depletion

Filters out ultraviolet (UV) radiation from the sun. It’s not desirable for the ozone to be depleting


4. Atmospheric Aerosol Loading

Aerosols have an impact on the Earth’s climate system


5. Ocean Acidification

CO2 emissions are absorbed by the ocean, leading to warming, altering of the ocean’s chemistry and decreasing the pH of the surface water (amongst other impacts)


6. Biogeochemical Flows (both of nitrogen and phosphorus separately)

The flow of Nitrogen & Phosphorus into the biosphere and oceans.

This occurs heavily as a result of agriculture (and the use of synthetic fertilizers may have something to do with this), and industrial activity


7. Freshwater Use

Human consumption of freshwater and drinking water, and the impact of climate change on the natural hydrological cycle


8. Land-System Change

The change in use of land, such as forests, grasslands, wetlands and other vegetation types that have primarily been converted to agricultural land.

There’s many negative impacts to this.


9. Biosphere Integrity (both of genetic diversity, and functional diversity separately)

Involves loss of biodiversity, and also extinction.

Biodiversity loss is the extinction of species (plant or animal) worldwide, and also the local reduction or loss of species in a certain habitat.


Right Now, Which Boundaries Have We Stayed Within, & Which Ones Have We Crossed?

You can see the graphic/visual illustration of the risk ratings of each planetary boundary at stockholmresilience.org.

As a summary of the labels they are tracked with, and the status of each according to that stockholm.org resource though:


Tracking Labels

The tracking labels for each boundary can be categorised into:

Boundary not yet quantified – grey

Below boundary (safe) – green

In the zone of uncertainty (increasing risk) – yellow

Beyond the zone of uncertainty (high risk) – red


Status Of Each Boundary

As of 2015, the boundaries fitted into these categories:

– Climate Change

In the zone of uncertainty (increasing risk)


– Release Of Novel Entities

Boundary not yet quantified


– Stratospheric Ozone Depletion

Below boundary (safe)


– Atmospheric Aerosol Loading

Boundary not yet quantified


– Ocean Acidification

Below boundary (safe)


– Biogeochemical Flows

Nitrogen is beyond the zone of uncertainty (high risk), & Phosphorus is also beyond the zone of uncertainty (high risk).

Nitrogen in particular is one of the boundaries that presents the highest risk right now along with generic diversity, and phosphorus slightly behind that


– Freshwater Use

Below boundary (safe)


– Land-System Change

In the zone of uncertainty (increasing risk)


– Biosphere Integrity

Functional Diversity has no global quantification, & Genetic Diversity is beyond the zone of uncertainty (high risk)


Core Planetary Boundaries

Some boundaries might be considered more critical than others.


scripps.ucsd.edu outlines that some of these boundaries could be ‘core boundaries’ that if altered would ‘drive the earth system into a new state.’


Control Variables & Exact Boundary Value For Each Of The Planetary Boundaries

There can be different ways to track, measure or assess each boundary.


This wikipedia.org guide outlines the different control variables for each of the planetary boundaries/earth-system processes

This ideas.ted.com resource also outlines the exact boundary line measurement/value for each boundary (e.g. for climate change, atmospheric concentrations of CO2 might not be at more than 350ppm)


Planetary Limits vs Thresholds

Planetary limits might be different to planetary thresholds.


This greenbiz.com resource explains the difference between planetary limits and thresholds, and explains how the boundaries might relate to sectors and companies, and what the targets of each sector might be


Using Planetary Boundary Concepts Alongside Other Sustainability & Environmental Concepts

The planetary boundaries concepts have been used alongside the ecological footprint concept to assess the trend of land clearing and turning available land into cropland into the future.



1. https://www.stockholmresilience.org/research/planetary-boundaries/planetary-boundaries/about-the-research/the-nine-planetary-boundaries.html

2. https://undark.org/article/ted-nordhaus-carrying-capacity-ecology/ 

3. https://www.stockholmresilience.org/research/planetary-boundaries/planetary-boundaries/about-the-research.html

4. https://www.stockholmresilience.org/research/planetary-boundaries.html

5. https://scripps.ucsd.edu/news/earth-has-crossed-several-planetary-boundaries-thresholds-human-induced-environmental-changes

6. https://en.wikipedia.org/wiki/Planetary_boundaries

7. https://ideas.ted.com/the-9-limits-of-our-planet-and-how-weve-raced-past-4-of-them/

8. https://www.greenbiz.com/article/7-steps-take-if-your-company-oversteps-its-planetary-boundaries


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