Planetary Boundaries: Explained
- AJ
- Apr 9, 2025
- 4 min read
Updated: Mar 5
In order to live sustainably, we must be aware of a safe space in which we can operate to limit our environmental impact. Our planet has boundaries for human consumption and we must stay within these boundaries to save future generations. As of 2023, there are nine boundaries that have been discovered: Climate Change, Biosphere Integrity, Land-System Change, Freshwater Change, Biogeochemical Flows, Ocean Acidification, Atmospheric Aerosol Loading, Stratosphere Ozone Depletion and Novel Entities.
(UPDATE 03/05/26: 7 planetary boundaries have now entered the danger zone. Ocean acidification boundary has now been crossed)
Crossing these boundaries increases the risk of abrupt and irreversible environmental changes. These boundaries are interdependent, meaning that when one boundary is crossed, it affects all the other planetary boundaries.
Climate Change
The changing ratio of incoming versus outgoing energy on Earth. Factors that contribute to this include greenhouse gases (CO2, CH4, N2O, H2O, HFCs, PFCs, SF6) and aerosols. Trapped radiation on Earth causes an increase in temperatures and changes climate patterns globally. This boundary has been crossed.
Biosphere Integrity
The overall decline of biodiversity. This threatens the biosphere’s ability to regulate the planet by impacting energy balance and natural chemical cycles on Earth. The loss of genetic diversity as well as the decline in the functional integrity of the biosphere have exceeded safe levels.
Land-System Change
The changing of natural landscapes through human activities like deforestation and urbanization. These activities diminish ecological functions like the carbon cycle, moisture recycling and wildlife habitats which are crucial for the planet's health.
Globally, the remaining forested areas have fallen below safe levels. We have drastically changed the land from what it used to be. Almost everything we do changes the natural landscape of the world from water usage to farming and industrial processes. We need to keep this impact in mind and limit our land use for our future.
Freshwater Change
As you can see from the diagram, freshwater is broken up into blue and green water. Green water includes soil moisture and blue water is freshwater sources such as lakes and rivers.
Humans change the natural cycle of freshwater by industrial and farming practices, taking the water from the ground, lakes and rivers. Approximately two thirds of Earth’s largest rivers are no longer free-flowing, meaning that these rivers do not follow their original paths. The biggest cause of this are human built dams and reservoirs.
We only have a certain amount of freshwater available on Earth, most of it being stored in ice caps, therefore we must treat water as a valuable asset. We are currently operating outside of the safe zone for freshwater change on this planet.
Biochemical Flows
Human disruption of natural nutrient cycles such as nitrogen and phosphorus cycles. These cycles are crucial in supporting life and maintaining our natural ecosystems on Earth. The global phosphorus flow into the ocean and the extraction of nitrogen from the atmosphere are disrupting the nutrient cycles beyond safe levels.
Ocean Acidification
Ocean acidification is just how it sounds, the ocean absorbs excess CO2 from the atmosphere (due to human reliance on fossil fuels) and becomes more acidic. This greatly harms ocean ecosystems such as coral reefs and calcifying organisms while diminishing the oceans ability to act as a carbon sink. We recently crossed this planetary boundary in 2025, sense the industrial revolution the ocean surfaces acidity has increase by 30-40% according to the Stockholm Resilience Center.
Atmospheric Aerosol Loading
This is the rise in airborne particles from human activities or natural sources that influences the climate by altering temperature and precipitation patterns. We are currently operating within the safe space of atmospheric aerosol loading on Earth.
Stratosphere Ozone Depletion
The Ozone layer protects Earth’s living organisms from the harsh rays of the sun (the reason life is able to exist on Earth). The thinning of the ozone layer is due to human-made chemicals which allows for harmful UV radiation to reach Earth’s surface. The recovery of the ozone layer is ongoing (the ozone layer can self-repair after human damage) and we are currently operating within the safe zone.
Novel Entities
This includes the introduction of synthetic chemicals and substances (microplastics and organic pollutants), radioactive materials (nuclear waste + weapons) and human interventions in evolutionary processes (GMOs). Currently, the amount of synthetic substances we create is FAR above a safe operating space.
We need to change how we do things if we want to keep Earth habitable for humans ! To see more you can go to planetaryhealthcheck.org, this was created by the Potsdam Institute for Climate Impact Research.
Action Needed
Corporations are starting to use set targets to lower their impact on the planet. Setting goals such as reducing carbon emissions in supply chains and using sustainable farming techniques. We know what we can do to cut back on exploiting our environment, this talk must be turned into action. The big corporations are to blame, as consumers, we can vote with our dollar. Do research on businesses and products before you purchase. What are they are doing to cut back their impact? Be sure your purchase is worth the environmental cost not only the dollar amount.
I know this is a lot of big words and complicated information, please let me know if you would like me to go in more depth into specific boundaries (like a post specifically about novel entities).
Thank you for reading :)
-AJ
4/9/25 - Updated 3/5/25
References:
Comments