1.2.7 Planetary boundaries
Helpful prior knowledge and learning objectives:
Helpful prior learning:
Section 1.1.1 The economy and you, which explains what an economy is and how it is relevant to students’ lives
Section 1.1.2 The embedded economy, which explains the relationship between the economy and society and Earth’s systems.
Section 1.1.3 Degenerative economies, which explain the problems for people and planet with the way our current economies operate.
Section 1.2.5 Ecosystems: Interactions, energy and the importance of biodiversity, which explains the role of energy, biotic interactions, and biodiversity in an ecosystem
Section 1.2.6 Biogeochemical cycles, which explains how the water and carbon cycles support all life on Earth.
Section S.1 Systems thinking, which explains what a system is and why systems thinking is useful. (coming soon)
Section S.x Stocks and flows, which explains a type of system with accumulations of energy, matter, information and other things that increase or decrease over time through inflows and outflows. (coming soon)
Section S.x Feedback loops and tipping points, which explains the roles of reinforcing and balancing feedback loops in amplifying or dampening change. (coming soon)
Learning objectives:
discuss the impact of economic activities on ecosystem function, with reference to planetary boundaries
You might think that we have only recently started to understand the risks of climate change and other ecological damage. But more than 50 years ago, a group of scientists from MIT used computer models to research how population and economic growth were affecting Earth’s resources. They published their research in 1972 in a best-selling book called The Limits to Growth.
The scientists concluded that if economic growth continued, even with slowing population growth and improved technologies, we could face a collapse of our economic and social systems within 100 years (from 1970) due to damage to Earth’s ecosystems. The scientists recommended significant changes to the economy to limit growth and protect Earth’s life-support systems.
Unfortunately many economists, business leaders and politicians dismissed the research. The scientists' conclusions and recommendations went against economic theories that assume that endless economic growth is possible and necessary. After huge initial interest in the Limits to Growth report, it was pushed aside as countries continued to blindly use energy and matter to grow their economies.
Recent research shows that many of the predictions of The Limits to Growth were correct, and new computer models are now being used to determine what we can still do to avoid the catastrophes predicted in the report. The models used in the MIT research and current research are enormously valuable, but only if we pay attention to what they tell us.
Figure 1. Warnings about ecological crises from more than 50 years ago
(Credit: Amazon/Wikipedia)
What are planetary boundaries?
Since the 1970s, scientists have continued research to understand how much damage human economic activity is doing to Earth’s systems. Scientists have identified nine interconnected Earth systems that are critical to maintaining stable conditions for life on Earth.
With the help of new computer models, scientists have identified probable limits to human disturbance of each of Earth’s systems. If we cross these limits, some planetary systems may reach a tipping point (Section S.x) where conditions change very rapidly with widespread risks for life on Earth.
The planetary boundaries model illustrates these nine Earth systems and their limits (Figure 2). The “safe operating space” for human economic activity is the green area within the dotted line. Research shows that we have crossed the safe operating space in six of nine Earth systems, with ocean acidification rapidly approaching the boundary.
Figure 2. Planetary boundaries model
(Credit: Stockholm Resilience Centre CC BY-NC-ND 3.0)
Climate change
This boundary measures levels of global warming.
Current global warming is +1.2-1.5°C from the pre-industrial period. The
main driver is greenhouse gas emissions from burning fossil fuels for energy.
Novel entities
(Chemical pollution)
Industries release hundreds of thousands of chemicals into the environment. Many chemicals are untested for ecosystem impacts, but can remain in ecosystems for very long periods causing irreversible damage to the way they function.
Stratospheric ozone depletion
Stratospheric ozone filters out harmful ultraviolet (UV) radiation from the sun. Man-made chemical emissions in the atmosphere have damaged the ozone layer. The Montreal Protocol, a global agreement, limited these damaging emissions, keeping us inside the planetary boundary.
Atmospheric aerosol loading
(air pollution)
Humans emit microparticles or aerosols, like soot from burning waste, into the atmosphere through industrial production and transportation. These particles are often toxic to plants and animals and affect cloud formation and rainfall patterns that disrupt ecosystems.
Ocean acidification
Carbon dioxide (CO2) dissolves in ocean water, forming carbonic acid that damages the exoskeletons of some animals and threatens corals and the habitats they provide for fish and other marine organisms.
Biogeochemical flows
(phosphorus and nitrogen)
Agriculture uses fertilisers with phosphorus and nitrogen that run off into rivers, lakes and oceans. They support excessive toxic algae growth that blocks light to other organisms, and depletes oxygen from water bodies when they die and decay.
Freshwater change
Excessive use of surface water (blue water) and groundwater (green water) for agriculture, industry and households depletes water stocks and flows, interfering with the water cycle which supports the transfer and transformation of energy and matter in ecosystems.
Land-use change
Humans convert land, such as forest and wetlands, for human uses such as agriculture, material extraction, and the built environment. Land conversion depletes soil carbon, destroys ecosystem habitats and harms the land’s ability to cycle water, nitrogen and phosphorus.
Biosphere integrity
(biodiversity)
Biodiversity is critical for ecosystem function and resilience. We have lost about 69% of Earth’s species since 1970 due to land use, pollution, and climate change.
You may have noticed that the same human economic activities - farming, overconsumption and the related industrial production, urbanisation - are causing us to cross multiple planetary boundaries. This is because of the wide ecological impacts of human transfers and transformations of energy and matter to meet our needs and wants. The multiple planetary boundary crossings also occur because these Earth systems are deeply connected to one another. For example, climate change amplifies biodiversity loss as habitats change. Land use amplifies climate change due to loss of forests and soils that sequester and store carbon.
Johan Rockström, one of the original creators of the planetary boundary model, briefly explains the model in the short video below. He then focuses on climate change to explain the multiple, interconnected tipping points we face in Earth’s climate system.
Activity 1.2.7
Concept: Systems
Skills: Thinking skills (critical thinking)
Time: 30 minutes
Type: Individual or pairs, then group
Connecting planetary boundaries
All Earth systems are interconnected, so the good news is that when we tackle one problem, we are likely to have positive impacts on the others.
With a partner, choose two of the planetary boundaries in Figure 2 and try to explain how they are connected. If you are working in a larger class group, make sure that each pair chooses a different set of planetary boundaries to work with.
When you have some ideas, join together with another student pair, and discuss your ideas and listen to theirs.
Figure 2. Planetary boundaries model
(Credit: Stockholm Resilience Centre CC BY-NC-ND 3.0)
Now, consider Figure 4. This illustration conveys an important message about so-called ‘carbon tunnel-vision’. What is the message of this illustration?
Discuss in your group, or with the entire class.
Figure 3. Carbon tunnel-vision
(Credit: Deivanayagam and Osborne)
Ideas for longer activities, deeper engagement, and projects are listed in Subtopic 1.5 Taking action
Checking for understanding
Further exploration
Breaking Boundaries - a documentary about planetary boundaries on Netflix. Difficulty level: easy
Tipping Points: The true story of the Limits to Growth - a fascinating 3-episode podcast about the original research behind Limits to Growth and how the research was undermined by economists, business and politics. Difficulty level: medium
Earth for All - A book that explores a number of scenarios for our collective future on the planet. The book uses research from new computer models about the impact of different actions and policies on human and ecological wellbeing. The scientist-authors present five big impact changes we can make to meet the needs all within planetary limits in a single generation. Difficulty level: medium
Institute for New Economic Thinking Lectures on[ECO]nomics
Planetary Boundaries - [ECO]NOMICS Part 3 - In this video lecture, Professor Juliet Schor explains planetary boundaries and why we need to live within them. She counters arguments often put forward by mainstream economics that there is a tradeoff between protecting the environment and our ability to consume goods and services. Difficulty level: medium
System Change - [ECO]NOMICS Part 4 - In this video lecture, Professor Juliet Schor argues that reducing working hours reduces CO2 emissions and other negative ecological impacts, while improving human wellbeing by freeing up time for relationships, leisure, learning and other low-carbon activities. Difficulty level: medium
Sources
Deivanayagam TA, Osborne RE (2023). Breaking free from tunnel vision for climate change and health. PLOS Glob Public Health 3(3). https://doi.org/10.1371/journal.pgph.0001684.
Earth for All. https://earth4all.life/
Meadows, D. H., & Randers, J. (2013). Limits to growth. Chelsea Green Publishing.
Raworth, K. (2017). Doughnut economics: seven ways to think like a 21st century economist. London: Penguin Random House
Richardson, K. et al. (2023). Earth beyond six of nine planetary boundaries. Science Advances, 9(37). DOI:10.1126/sciadv.adh2458
Shields, K. (Host). (2022). Tipping Point: The True Story of The Limits to Growth. https://tippingpoint-podcast.com/.
Terminology (in order of appearance)
Link to Quizlet interactive flashcards and terminology games for Section 1.2.7 Planetary boundaries
climate change: a change in the temperature and precipitation patterns in an area, in recent times due to human economic activities
economic growth: an increase in the total value of goods and services produced in a period of time
system: a set of interdependent parts that organise to create a functional whole
ecosystem: the interaction of a community of organisms with their physical environment
economy: all the human-made systems that transfer and transform energy and matter to meet human needs and wants
tipping point: a condition where even a small further change can push a system into a different state
planetary boundaries model: a model that illustrates these nine Earth systems and their limits
ocean acidification: a reduction in the pH of the ocean over time, caused primarily by absorption of carbon dioxide
global warming: the rise in the average temperature of Earth's air and oceans (due to human activities)
novel entities: things (mainly chemicals) created and introduced into the environment by human beings that could have disruptive effects on the earth system
stratospheric ozone: a naturally-occurring gas in the atmosphere that filters the sun's ultraviolet (UV) radiation
ultraviolet (UV) radiation: electromagnetic radiation from the sun with wavelengths of 10–400 nanometers
Montreal Protocol: an international agreement that protects the ozone layer by reducing ozone-depleting substances
aerosols: small solid particles or liquid droplets suspended in air
carbon dioxide (CO2): gas produced by burning carbon or organic compounds and through respiration, naturally present in the atmosphere and absorbed by plants in photosynthesis
carbonic acid: an acid formed when carbon dioxide dissolves in water
exoskeleton: a rigid external covering for the body in some animals
habitat: the natural home or environment of an animal, plant, or other organism
fertiliser: a chemical or natural substance added to soil or land to increase its fertility
phosphorus: an important element for living organisms as a component of adenosine triphosphate (ATP) which is the primary energy source for organisms' cells
nitrogen: an element that occurs as a gas which makes up 78 percent of the atmosphere and that forms a part of all living tissues
algae: a diverse group of aquatic organisms that conduct photosynthesis
surface water: water that collects on the surface of the ground, like lakes and rivers; also known as blue water
groundwater: water that collects underground in soil or in rock crevices and pores
stock: an accumulation of something, such as energy, matter, information, or money
flow: movement of something such as energy, matter, information or money between stocks
water cycle: the stocks and flows of all water on Earth
transfer: to move something from one place to another
transform: a change in the state, energy or chemical nature of something
energy: the ability to do work or cause change
matter: anything that takes up space and has mass
wetland: a distinct ecosystem flooded or saturated by water, either permanently or seasonally
extraction: taking something away from somewhere else, especially using effort or force
built environment: human-made structures or conditions in an area
biodiversity: the variety of living organisms on Earth
pollution: the presence of a substance that has harmful effects on the environment
sequester: to remove and store something