Stockholm planetary boundaries are a set of nine global environmental systems that define what the originators call a” safe operating space for human development “for planet Earth.
The purpose of developing the Stockholm planetary boundaries was to identify areas or systems critical to survival on Earth, quantify the current state of these systems, estimate the tipping points or thresholds at which these systems are on the verge of catastrophic, irreversible change detrimental to human life, and to use demonstrated changes in these systems as a guide to promote environmental policy that keeps these systems below the tipping point.
The Stockholm planetary boundaries were developed by a group of 26 environmental scientists, climate scientists, and academics led by Johan Röckstrom of the Stockholm Resilience Centre and Will Steffen of the Australian National University. The first report on the Stockholm planetary boundaries was presented in 2009. In 2015, a paper presented at the World Economic Forum in Davos, Switzerland, updated the planetary boundaries concept.
The Stockholm planetary boundaries are based on the concept that hundreds of years of human technological and industrial changes have substantially altered various earth systems. The boundaries are an attempt to quantify this change and define a safe space in which human development can proceed without endangering human survival.
The Stockholm Resilience Center, associated with Stockholm University in Sweden, has identified, quantified, and is monitoring nine systems scholars at the center believe must be kept within certain limits for humans to survive. These systems are climate change, biosphere integrity (biodiversity loss), biogeochemical cycles of nitrogen and phosphorous, ocean acidification, land use, freshwater, ozone depletion, atmospheric aerosols, and chemical pollution. Each system is given a numerical boundary value, a current value, and for comparison, a pre-industrial value. In 2015 in a paper in Science, a group of 18 researchers associated with the Stockholm Resilience Centre declared that four of these boundaries—climate change, biosphere integrity, land use, and biogeochemical cycles—have been crossed.
Biosphere integrity refers to the maintenance of biodiversity. Studies have shown that loss of biodiversity, including species extinction due to human activity, is more rapid in the past 50 years than at any other time in human history. Causes for the loss of biodiversity include increased demand for food (high agricultural production), water, and natural resources. This boundary has also been crossed.
Agricultural and industrial activities have disrupted the natural levels of nitrogen and phosphorous in air and water. Millions of tons of nitrogen are withdrawn from the atmosphere and converted into fertilizer. Some of this nitrogen is taken up by plants, but much of it is washed away and accumulates in bodies of water. Likewise, excessive amounts of phosphorous end up in rivers and oceans, causing disruption in the aquatic ecosystem. For example, aquatic algal blooms are caused by excessive amounts of nitrogen and phosphorous in combination with specific environmental conditions. As the algae grow, they release toxins that, which are taken up by shellfish. Consuming these shellfish make humans sick. The toxins also harm fish and other aquatic species, altering the aquatic ecosystem. This threshold has also been passed.
About 25% of CO2 released into the atmosphere ends up in oceans. As CO2 dissolves in water it creates carbonic acid. This changes the acidity of the water and the availability of the form of carbon used by many marine animals. The effects of increased acidification can be seen in the death of coral reefs. The coral reefs provide habitat for many species, leading to a reduction in biodiversity. Coral reef death has a ripple effect on the ocean's ecosystem and illustrates the close connection between different planetary boundaries. Data suggests that the ocean acidification is near its boundary level.
Pressure to produce more food and build more houses causes changes in land use. Converting forests, jungles, and prairies to cropland, building on wetlands, and covering large acreage with solar panels cause changes in the terrestrial ecosystem, reduce biodiversity, and affect the freshwater system. Increasing crop acreage increases biogeochemical run-off. Irrigation increases water usage. The threshold for land use change has already been passed.
Water is essential to life, and it is estimated that by 2050, 500 million people will experience water stress. A preview of this stress occurred in Cape Town, South Africa, in 2018 when prolonged drought caused severe water rationing. The freshwater cycle is linked to climate change. It also is affected directly by human activity such as irrigation of cropland, altering the course of rivers with dams and flood control construction, and changes in the pattern of water vapor flow related to land use, deforestation and atmospheric aerosols.
The ozone layer is a blanket of gas with a high concentration of ozone gas that exists in the stratosphere about 6.2 miles (10 km) above Earth. The ozone in this layer absorbs most of the harmful ultraviolet (UV) radiation from the sun. Exposure to UV radiation causes skin cancer in humans and damage to marine and terrestrial ecosystems. The effects of the ozone hole over Antarctica are measurable. The Montreal Protocol of 1987 is a global agreement to protect the stratospheric ozone layer by phasing out the use of ozone-depleting substances. This agreement, if adhered to, is likely to keep ozone depletion below the threshold boundary.
Atmospheric aerosols are tiny particles suspended in the air. These particles affect climate and interact with water vapor flow, altering the freshwater cycle. In addition, inhaling these particles negatively affects human and animal health. Over 4 million people die prematurely each year from the effects of inhaled pollution. Because of their diverse nature and complex interactions, a boundary value for atmospheric aerosols has not yet been defined.
Responses to the concept of Stockholm planetary boundaries presented in 2009 continue to be expressed and the the concept continues to evolve. There is also debate about which boundaries are the most important and deserve the most effort to maintain.
In general, the concept of planetary boundaries has met with three responses. One group of scientists, including several Nobel Prize winners, believes the concept is an important one that should be embraced globally. This group cites its concept of growth within defined limits as an improvement over the current approach to environmental threats. The United Nations has acknowledged the concept of planetary boundaries in several of its policies.
A second group has reservations about the usefulness of the boundary concept unless there is political will to implement it globally. This group suggests that the concept of boundaries to growth pits already developed countries against developing countries, making global implementation highly unlikely.
A third group objects to the idea of a threshold and a safe zone. This group claims governments will feel the need to make few if any changes before they reach the boundary value. They point out that the boundary values are estimated and that the tipping point could be easily be exceeded if action is delayed by a false sense of security the boundary provides.
See also Acid rain ; Air pollution ; Climate change ; Ozone ; Water pollution .
Norman, Barbara. Sustainable Pathways for Our Cities and Regions: Planning within Planetary Boundaries. New York: Routledge, 2018.
Röckstrom, Johan, and Mattias Klum. Big World, Small Planet: Abundance within Planetary Boundaries. New Haven, CT: Yale University Press, 2015.
O'Neil, Daniel W., et al. “A Good Life for All Within Planetary Boundaries.” Nature Sustainability 1 (2018): 88–95. https://www.nature.com/articles/s41893-0180021-4 (accessed April 12, 2018).
Steffen, Will, Johan Röckstrom, and Robert Costanza. “How Defining Planetary Boundaries Can Transform Our Approach to Growth.” Solutions 2, no. 3 (May 2011): 59–65. https://www.thesolutionsjournal.com/article/how-defining-planetary-boundaries-cantransform-our-approach-to-growth (accessed April 12, 2018).
Planetary Boundaries Research Network. “Planetary Boundaries.” http://www.pb-net.org (accessed April 12, 2018).
Stockholm University. “Four of Nine Planetary Boundaries Now Crossed.” https://www.su.se/english/about/news-and-events/press/press-releases/four-of-nine-planetary-boundaries-now-crossed-1.218003 (accessed April 12, 2018).
Stockholm Resilience Centre, Stockholm University, Kräftriket 2B, Stockholm, SE-10691, Sweden, +46 8 674 70 70, info@stockhol,resilience.su.se, http://www.stockholmresilience.org .
Revised by Tish Davidson, AM