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A sustainable future
The impact of humans on the planet is widely understood to be causing significant environmental damage, and jeopardising the ability of future generations to live a high quality of life. Most famously, the concentration of carbon dioxide in the atmosphere has risen far above that what would be expected without human influence. This has been linked to the greater occurrence of wildfires, droughts, and other ecosystems change.
Planetary Boundaries
Planetary Boundaries
It is not just climate change that threatens the wellbeing of people. Contemporary research has identified nine Planetary Boundaries that when exceeded can cause an irreversible change to vital Earth systems (Richardson et al., 2023). These Earth systems have created the habitable conditions in which humanity has prospered. The Earth can exist in one of several meta-stable conditions, and changes from one to the other as it has done in throughout its history. An ice age is a classic example. Since the last ice age, the present day Holocene epoch has provided a relatively stable environment for us. The anthropogenic influence on the Earth is now so considerable that it is feasible that the resulting change in Earth systems could be catastrophic to society (Rockström et al., 2009).
The Planetary Boundary wagon wheel infographic. Data bars represent the magnitude of each environmental impact compared to the Planetary Boundary. Impacts exceed the Planetary Boundary if they extend past the red circle.
The nine Planetary boundaries summarise the important Earth systems. Some of the Planetary Boundaries have multiple indicators. The Planetary Boundaries are quantified, providing us with a 'safe operating space' (SOS). The SOS is the limit to which human activities can put pressure on natural phenomena without causing long term or permanent changes to Earth systems. Six of the 9 Planetary Boundaries have had the SOS exceeded. This assessment changes with time as new data becomes available (Stockholm Resilience Centre, 2025).
Climate change
Climate change
SOS exceeded
Planetary Boundary: 350 ppm CO2 and 1 W/m2 radiative forcing.
Current value: 417 ppm CO2 and 2.9 W/m2 radiative forcing.
Climate change is the most reported upon Planetary Boundary. Changes to the atmospheric carbon dioxide are mostly due to fossil fuel combustion. Radiative forcing refers to excess heat building up in the atmosphere.
Biodiversity
Biodiversity
SOS exceeded
Planetary Boundary: less than 10 extinctions per million species a year and less than 10% of living matter influenced by human purposes.
Current value: over 100 extinctions per million species a year and 30% of living matter influenced by human purposes.
As with many Planetary Boundaries, biodiversity is linked to others. Species extinction is linked to deforestation and climate change interfering with food and habitat.
Ozone layer
Ozone layer
Below SOS
Planetary Boundary: ozone concentration of 276 Dobson units.
Current value: 285 Dobson units.
The ozone layer was depleted by CFC emissions. It has since recovered due to regulations and is, on average, within the SOS.
Oceans
Oceans
Below SOS (just)
Planetary Boundary: At least 80% of pre-industrial carbonate levels.
Current value: 81%.
Carbonate, a component of seashells and limestone, regulates the pH of ocean water. The oceans absorb a lot of carbon dioxide from the atmosphere, but over time this causes acidification and loss of carbonate. Then the ocean becomes less effective as a carbon sink.
Fertiliser
Fertiliser
SOS exceeded
Planetary Boundary: Global phosphorous (P) flow from freshwater to ocean of 11 million tonnes (MT)/year, regional P flow from soil to freshwater of 6.2 MT/year, nitrogen (N) fixation of 62 MT/year.
Current value: Global P of 22.6 MT/year, regional P of 17.5 MT/year and N fixation of 190 MT/year.
The use of fertiliser introduces a lot of P and N into soils, much of which is washed into freshwater sources. This then creates eutrophication which impairs water quality.
Land use
Land use
SOS exceeded
Planetary Boundary: 75% of natural forest remaining.
Current value: 60%.
Deforestation, primarily for farmland, removes trees and diverse species and replaces it with single crops (monocultures). This reduces biodiversity. Trees are also acting to remove carbon dioxide from the atmosphere and are a vital part of many ecosystems.
Freshwater
Freshwater
SOS exceeded
Planetary Boundary: Freshwater (bluewater) withdrawals no more than 10.2% of total water flow, and precipitation (greenwater) use no more than 11.1%.
Current value: 18.2% and 15.8%.
Water is removed from rivers, lakes, reservoirs and groundwater sources for agriculture, industry, and domestic uses. If too much water is used it can reduce water availability for natural environments causing the collapse of ecosystems.
Air quality
Air quality
Below SOS
Planetary Boundary: Aerosol loading of 0.1 (based on amount of light blocked by aerosols in atmosphere).
Current value: 0.076.
Aerosols are particles, solid or liquid, dispersed in the atmosphere. They have a role in regulating temperature and air quality.
Pollution
Pollution
SOS exceeded
Planetary Boundary: Zero unnatural and untested substances in the environment.
Current value: Unknown, but much higher than zero (100,000+).
This Planetary Boundary is hard to measure, but we understand that many unforeseen consequences may arise from the release of chemicals into the environment. It is a 'better safe than sorry' approach to establish this as a Planetary Boundary.
References
References
Earth beyond six of nine planetary boundaries: Richardson, K., Steffen, W., Lucht, W., Bendtsen, J., Cornell, S.E., Donges, J.F., Drüke, M., Fetzer, I., Bala, G., von Bloh, W., Feulner, G., Fiedler, S., Gerten, D., Gleeson, T., Hofmann, M., Huiskamp, W., Kummu, M., Mohan, C., Nogués-Bravo, D., Petri, S., Porkka, M., Rahmstorf, S., Schaphoff, S., Thonicke, K., Tobian, A., Virkki, V., Wang-Erlandsson, L., Weber, L. and Rockström, J., Sci. Adv. 2023, 9, eadh2458.
A safe operating space for humanity: Rockström, J., Steffen, W., Noone, K., Persson, A., Chapin III, F.S., Lambin, E.F., Lenton, T.M., Scheffer, M., Folke, C., Schellnhuber, H.J., Nykvist, B., de Wit, C.A., Hughes, T., van der Leeuw, S., Rodhe, H., Sörlin, S., Snyder, P.K., Costanza, R., Svedin, U., Falkenmark, M., Karlberg, L., Corell, R.W., Fabry, V.J., Hansen, J., Walker, B., Liverman, D., Richardson, K., Crutzen, P. and Foley, J.A., Nature 2009, 461, 472-475.
Planetary Boundaries: Stockholm Resilience Centre, 2025.
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