The Nine Planetary Boundaries: An Introduction

Written by
Rae Lewark

The Nine Planetary Boundaries: An Introduction

Written by
Rae Lewark

Within an ecosystem, each species has its place and role within the flow of energy and matter. Ecosystems develop over thousands of years and adapt as conditions change. Human impact on the environment has surpassed any other species in natural history. Through industrialization, humans have harnessed the earth’s resources to maximize utility, perfecting the built environment to modern human design. But with increasing ecological changes we see what considerations have been left in the shadows of progress; natural resources unable to replenish to meet demand leading to dwindling and degraded supply. We must examine how we operate in relation to the environment, address the boundaries we have already crossed, and develop new methods to ensure a prosperous and sustainable future.

In 2009, the Stockholm Resilience Centre brought together 26 researchers to address the environmental changes being observed across the planet. They determined there are a total of nine planetary boundaries, categorized by biogeochemical cycles, water, circulation systems, biophysical features, and global change. (Figure 1)

Figure 1. Definition of the nine planetary boundaries. The current state of risk is identified for each boundary as well as some of the values that are considered that are used to determine the threshold levels.

Standing on the shoulders of the scientists behind the 1972 publication “Limits to Growth,” they developed a methodology for quantifying the impacts of human activity on the earth’s ecosystems.  Beyond this, they aimed to understand our current state of operation and threshold level that will cause irreversible damage to our planet (Rockstrom et al 2009, Butler 2017). (Figure 2)

Figure 2. Operating states for the planetary boundaries. In green, is the safe zone. Once the threshold limit has been reached, the planetary boundary enters into a zone of increasing risk, past that may be high risk at which humanity may not be able to be sustained. Currently, three planetary boundaries are operating beyond the threshold - two operating at high risk and one operating at increasing risk.

Each planetary boundary has a threshold at which below we are in a level of safe operation and humanity thrives, but when we breach cross the our boundary threshold limit, damage occurs, and we are at a higher risk of not being able to sustain our economy (Rockstrom 2009, Butler 2017). When we compound the categories, we see a full picture of the environmental risks we are facing (O’Neil 2018).

Scientists have quantified the boundary limits of seven of the nine boundaries, thus we understand the trigger that causes the transition from operating below the threshold limit to operating beyond the threshold. As of 2022, we have crossed beyond our safety limit in three of the nine boundaries: biogeochemical flows, biosphere integrity, and atmospheric stability. (Rockstrom et al 2022).  For example, the boundary limit for atmospheric stability is an atmospheric CO2 concentration of 350 ppm (Rockstrom et al 2022). This value has already been reached and we are currently operating beyond the threshold in the zone of uncertainty. We need to investigate the possibility of transitioning back to below the threshold and if it is possible, the triggers that cause these transitions for all the planetary boundaries.

When a boundary is crossed a cascade of negative ecological effects begin. The intricate ecological systems cannot recover or adapt to the conditions, which has the potential to disrupt the ecological viability of a resource, a bioregion, or even the planet as a whole. Some boundaries such as loss of biosphere integrity are easy to quantify as they are simple to observe and measure. More complex boundaries such as novel entity release (chemical pollution) and atmospheric aerosol loading are harder to quantify due to limited understanding and testing coverage.

Future Considerations

When faced with the complexity of nine boundaries teetering on the brink of ecological degradation it is hard to see a viable path forward. Our access to the bounties of these boundaries is not inherently harmful, but we must rethink how we are allocating and utilizing these resources. By designing systems that aim for safe operating limits within their associated boundaries we can begin to address the risk levels currently threatening the planet (Rockstrom 2009, Steffen 2015). While The Nine Planetary Boundaries give us a framework to reduce our impact, we begin to challenge the idea that humans and the environment operate in isolated systems. We should not be aiming to be “less negative” but rather cooperative within the nine planetary categories. When we design systems that don’t breach the balance in each of these categories but instead connect and harmonize, we create systems capable of long-term planetary sustainability. We have the tools at our fingertips to innovate the way humankind and the environment interface. The time has come for us to redefine what it means to live and create on this planet.  

Be on the lookout for upcoming blogs focusing on each boundary, case studies to address their impacts, and applications of MBSE to aid in their mitigation and resolution.  


Butler, D.C., (2017). Limits to growth, planetary boundaries, and planetary health. Current Opinion in Environmental Sustainability, 25,

O’Neill, D.W., et al (2018). A good life for all within planetary boundaries. Nature Sustainability 1, 88–95.

Rockstrom, J., et al, (2009). Planetary Boundaries: Exploring the Safe Operating Space for Humanity. Ecology and Society, 14(2).  

Steffen, W., et al., (2015). Planetary boundaries: Guiding human development on a changing planet. Science 347, 6223. DOI:10.1126/science.1259855.

2017 Studio SE, Ltd.