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Stockholm Resilience Centre · Potsdam Institute for Climate Impact Research
Planetary Boundaries
Planetary Boundaries v3.0 (2023)
For the first time, all nine planetary boundaries have been assessed. Six planetary boundaries are found currently to be transgressed. For all of the boundaries previously identified as transgressed [climate change, biosphere integrity (genetic diversity), land system change, and biogeochemical flows (N and P)], the degree of transgression has increased since 2015 (v2.0).
Throughout our collaboration with the esteemed researchers at the Stockholm Resilience Centre and the Potsdam Institute for Climate Impact Research, we have been privileged to contribute to the visualisation and communication of planetary boundaries over the years.
Planetary boundaries are a set of key concepts related to Earth's capacity to maintain a stable and habitable environment for human life. These concepts are based on complex system science (CSS) and Earth system science (ESS), which study the interactions among various components of the Earth system. The planetary boundaries framework was first proposed in 2009 by a group of Earth system and environmental scientists led by Johan Rockström, then director of the Stockholm Resilience Centre. They identified nine critical processes that regulate the Earth's stability and resilience. Here are the key concepts:
Planetary Boundaries
These are the thresholds or limits beyond which significant, potentially irreversible changes to Earth's ecosystems and the global environment could occur, endangering the planet's habitability.
Earth System Processes
The planetary boundaries are associated with nine essential Earth system processes that help maintain the stability and resilience of the Earth system. They are:
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Climate change refers to the long-term alterations in Earth's temperature, precipitation patterns, and other meteorological phenomena, primarily driven by anthropogenic greenhouse gas emissions. The concentration of atmospheric carbon dioxide has surpassed 418 ppm, the highest level in the past 800,000 years at least. This boundary is of planetary and societal significance because it directly affects global ecosystems, weather patterns, and the frequency of extreme events, posing risks to agriculture, infrastructure, human health, and the stability of ecological systems.
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The rapid decline in global biodiversity, driven by habitat destruction, overexploitation, pollution, and climate change, has led to what is now recognized as the Earth's sixth mass extinction. Species are currently going extinct at a rate 1,000 times higher than the background rate. Biodiversity loss is of planetary and societal significance because it weakens the resilience of ecosystems, reduces the availability of natural resources, and compromises the essential services
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The biogeochemical flows of nitrogen and phosphorus have been dramatically altered by human activities, such as fertilizer application and fossil fuel combustion. Approximately 80% of nitrogen and 75% of phosphorus applied to croplands end up in the environment. Disruptions to these elemental cycles are of planetary and societal significance because they can lead to eutrophication, biodiversity loss, and the creation of oxygen-depleted "dead zones" in aquatic ecosystems, undermining water quality and fisheries.
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Novel entities encompass new substances, organisms, and technologies introduced into the environment by human activities, such as synthetic chemicals, genetically modified organisms, and nanomaterials. Over 350,000 different chemicals and mixtures are commercially available, with many having unknown long-term impacts. This boundary is of planetary and societal significance because novel entities can disrupt ecosystems, bioaccumulate in food chains, and pose risks to human health and the environment, often with unpredictable and far-reaching consequences. Addressing this boundary is essential for preserving the integrity of Earth's systems and safeguarding the well-being of present and future generations.
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Land-system change encompasses the conversion of natural landscapes, such as forests and wetlands, into agricultural and urban areas. Since the 1960s, the world has lost approximately 20% of its forest cover. This boundary is crucial because land-system change can result in habitat loss, biodiversity decline, soil degradation, and disruptions to the global carbon cycle, undermining ecosystem services and exacerbating climate change.
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The unsustainable extraction and consumption of freshwater resources have led to the depletion of rivers, lakes, and aquifers. Agriculture accounts for about 70% of global freshwater withdrawals. This boundary is critical because water scarcity threatens food security, human health, and economic development, exacerbating social tensions and heightening the risk of geopolitical conflicts over access to water resources.
2022 Update -
The depletion of stratospheric ozone, primarily caused by the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances, reduces the protective barrier against harmful ultraviolet (UV) radiation. The 1987 Montreal Protocol led to a nearly 99% reduction in controlled ozone-depleting substances. This boundary is of planetary and societal importance because increased UV radiation can cause skin cancer, cataracts, and immune system suppression in humans, as well as damage to ecosystems and agricultural productivity.
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As oceans absorb anthropogenic carbon dioxide emissions, their pH levels decrease, resulting in a more acidic environment. Since the beginning of the Industrial Revolution, the global oceanic pH has dropped by 0.1 units. This planetary boundary is crucial because ocean acidification negatively impacts marine life, particularly calcifying organisms such as coral reefs and shellfish, threatening biodiversity, food security, and the livelihoods of millions of people dependent on ocean resources.
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Aerosols, tiny solid or liquid particles suspended in the atmosphere, influence air quality, human health, and climate. Fine particulate matter (PM2.5) is responsible for an estimated 4.2 million premature deaths globally each year. Addressing this boundary is vital because aerosols can cause respiratory and cardiovascular diseases, disrupt regional weather patterns, and impact global climate through their interaction with sunlight and cloud formation.
Planetary Boundaries v3.0 (09.2023)
What’s new?
For the first time, the boundary for novel entities has been quantified, revealing that we have exceeded it. This includes the build-up of human-made chemicals like micro-plastics, pesticides, and nuclear waste. Additionally, scientific data is now available to measure the limit for atmospheric aerosol loading. While this limit hasn't been globally surpassed, regional oversteps have been identified, such as in South Asia. The boundary concerning freshwater now encompasses both green water (found in soil and plants in areas like farms and forests) and blue water (found in rivers and lakes), and both these limits have been breached. Another groundbreaking addition is a control variable for biosphere integrity, which shows that we've been exceeding this limit since the late 1800s, a period marked by significant growth in global agriculture and forestry. This study emphasises that planetary resilience encompasses much more than just climate change.
Reference:
Katherine Richardson et al., Earth beyond six of nine planetary boundaries. Science Advances. 9, eadh2458 (2023). DOI:10.1126/sciadv.adh2458
Planetary Boundaries v3.0 (2023)
This new visualisation of planetary boundaries was created in collaboration with the scientists from the Potsdam Institute for Climate Impact Research. It differs from Figure 1 in the paper because it uses a different normalised baseline. In Figure 1, the values from control variables are normalised such that the origin (the centre) represents mean Holocene conditions, and the planetary boundary (from green to yellow) has the same radius for all boundaries. In this visualisation, however, it is normalised so that the planetary boundary and the transition from the Increasing Risk Zone to the High Risk Zone are consistent for all boundaries. This approach was adopted in versions 1 (2009) and 2 (2015).
Related concepts
Safe Operating Space (SOS)
The "Safe Operating Space" refers to the collective range defined by scientifically-set boundary levels for nine critical biophysical systems and processes that govern Earth's life support systems. Transgressing these boundaries jeopardises the conditions vital for human development and well-being.
Planetary Resilience
Planetary resilience refers to the Earth's capacity to maintain its vital biophysical systems and processes within safe boundaries, ensuring stability and support for life. This concept is anchored in the understanding of planetary boundaries. Transgressing these boundaries poses risks to the stability and resilience of the Earth system, potentially resulting in significant environmental damage. The objective is to maintain the Earth in a "Holocene-like" state, the only known planetary condition that has reliably supported modern human civilisation.
Holocene-like
Modern humans have thrived on Earth for about 200,000 years, enduring through Ice Ages and warm periods, predominantly as hunter-gatherers. The Holocene, which began around 12,000 years ago, marked a stable Earth state, paving the way for agriculture and modern civilisations. The Planetary Boundary framework uses this "Holocene-like" state as a reference to understand how much planetary change can be tolerated without jeopardising conditions similar to those of the Holocene, which are known to support our current world. This approach is exemplified by the climate planetary boundary being set at 350 ppm CO2, instead of the original Holocene level of 280 ppm.
Tipping Points 🌍⚖️
Tipping points refer to thresholds where critical components of the Earth system can shift into a drastically different state, whereas planetary boundaries are limits beyond which risks to the Earth's systems become unsafe. While crossing a planetary boundary doesn't necessarily mean surpassing a tipping point, the concept of tipping points informs the establishment of these boundaries to ensure the Earth's systems remain stable and interlinked processes are considered.
Our dedicated page: globaia.org/tipping
Safe and Just Earth System Boundaries 🌍🕊️
The recent Earth system boundaries (ESB) assessment expands upon the planetary boundaries framework by integrating concepts like climate justice, doughnut economics and the Sustainable Development Goals. The ESBs emphasise a safe and just operating space and prioritise scaling quantitative boundaries across local to global levels. Developed by the Earth Commission, the ESBs aim to prevent significant harm to individuals by identifying eight specific control variables for five core planetary processes, serving as the foundation for actionable, science-based targets at regional and local scales.
Our dedicated page: globaia.org/safeandjust
References:
PB v1.0 · Seminal 2009 Nature paper: A safe operating space for humanity
PB v2.0 · 2015 Science paper: Planetary boundaries: Guiding human development on a changing planet
PB v3.0 · 2023 Science Advances paper: Earth beyond six of nine planetary boundaries
Newly assessed Novel Entities boundary: Outside the Safe Operating Space of the Planetary Boundary for Novel Entities
New assessed Green Water boundary: A planetary boundary for green water
Other relevant project: Breaking Boundaries — The Science of Our Planet
Same data but two ways of visualising it. In the left-hand side figure, the values for control variables are normalised to the mean Holocene conditions (centre) and the upper limit of the Safe Operating Space. In the right-hand side one, values for control variables are normalised to the upper limit of the Safe Operating Space and the transition from the Increasing Risk Zone to the High Risk Zone.
Pre-2023 Work on Planetary Boundaries
The updated Planetary Boundaries framework (2022), showing the newly assessed boundary for ‘novel entities’ (aka chemical pollution), as well as the distinction between ‘blue water’ (freshwater use of rivers, lakes, reservoirs and renewable groundwater stores) and ‘green water’ (terrestrial precipitation, evaporation and soil moisture). For simplicity, this version does not show the ‘zone of uncertainty’.
REF: https://pubs.acs.org/doi/10.1021/acs.est.1c04158 & https://www.nature.com/articles/s43017-022-00287-8
Planetary Boundaries 2009-2022 | From 3 to 6 boundaries crossed — The evolution of this influential scientific framework over time.
Professor Johan Rockström discussing the planetary boundaries
The updated Planetary Boundaries framework (2022), showing the new assessed boundary for ‘novel entities’ (aka chemical pollution). REF: https://pubs.acs.org/doi/10.1021/acs.est.1c04158
Planetary Boundaries over time
Planetary Arteries & Human Interventions
Red lines correspond to non-free-flowing rivers, that is rivers or sections of rivers that do not have a continuous and unobstructed flow of water.
These rivers may have been altered by humans through damming, diversion, or other modifications, which can result in changes to the river's natural flow regime.
Ocean pH in 2100
According to projections based on current trends in greenhouse gas emissions and ocean acidification, by 2100, the global average ocean pH is expected to decrease by 0.3-0.4 units, resulting in a more acidic marine environment. This significant shift in ocean chemistry, driven primarily by increased absorption of anthropogenic carbon dioxide, will have profound impacts on marine ecosystems, biodiversity, and the overall health of the world's oceans, posing significant challenges to the sustainability of our planet's marine life and resources
Aragonite saturation in 2100
Aragonite saturation is a key parameter in ocean chemistry that reflects the concentration of aragonite, a form of calcium carbonate, in seawater. It is an essential measure of the ability of marine organisms, such as shellfish, corals, and some plankton, to build and maintain their shells or skeletons. Projections for 2100, based on various emission scenarios, suggest that the global average aragonite saturation state will continue to decline.
A collage of additional versions created in the early 2010s.