Core idea: sustainability

• Sustainability = the extent to which practices allow the long-term viability of a system.

• In ESS, it usually means maintaining socio-ecological systems so there is no diminishment of conditions for future generations.

• A system is more sustainable when it has greater resilience: it can resist disturbance, avoid tipping points, and recover more effectively.

The three pillars of sustainability

• Environmental sustainability = using and managing natural resources so they can be replaced, while ecosystems can recover and regenerate.

• Focus on resource depletion, pollution, biodiversity conservation, and ecosystem regeneration.

• Social sustainability = building structures that support human well-being, such as health, education, equity, community, and cultural continuity.

• Also includes survival of societies and cultures, including language, belief systems, and spiritual practices.

• Economic sustainability = creating systems of production and consumption that can support human needs into the future.

• Key ESS point: there is no true economic sustainability without environmental sustainability.

• Be able to contrast weak sustainability (3 overlapping pillars) with strong sustainability (the economy embedded in society, and both embedded in the environment).

This diagram compares weak sustainability with strong sustainability. It is useful for ESS because it shows why the environment is the foundation for society and the economy, not just an equal partner. Source

Sustainable development

• Sustainable development = development that meets present needs without compromising future generations’ ability to meet their own needs.

• It applies sustainability to social and economic development.

• It aims to balance economic stability, social equity, and ecological integrity.

• The Brundtland Report (1987) is the classic source of this definition and introduced the strong link between environmental, social, and economic dimensions.

Unsustainable resource use and ecosystem collapse

• Unsustainable use of natural resources can push systems beyond recovery and cause ecosystem collapse.

• You need one named example of collapse caused by human overexploitation.

• Classic example: Newfoundland cod fisheries collapsed because of overfishing, showing that resource extraction above sustainable limits can destroy livelihoods and ecosystem structure.

• Exam link: connect this to tragedy of the commons, loss of resilience, and failure to manage maximum sustainable yield.

Measuring development: GDP vs sustainability

• GDP (gross domestic product) measures the monetary value of final goods and services produced and sold in a country over a given period.

• ESS criticism: GDP ignores the value of natural systems and environmental damage, so it can encourage unsustainable development.

• Growth in GDP can occur while natural capital declines.

• Green GDP attempts to correct this by subtracting environmental costs from GDP.

• Be ready to explain why a country can appear to develop economically while becoming less sustainable environmentally.

Environmental justice

• Environmental justice = the right of all people to live in a pollution-free environment and have equitable access to natural resources, regardless of race, gender, income, or nationality.

• Sustainable development problems are often also justice problems.

• In ESS, use one local and one global example of environmental injustice.

• Possible examples named in the syllabus include landfills in low-income areas, Bhopal (1984), Deepwater Horizon (2010), plastic waste exported from developed to developing countries, and Maasai land-rights issues.

• Exam focus: identify who benefits, who bears the costs, and whether access to water, food, energy, or land is equitable.

Inequality and access to resources

• Inequalities in income, race, gender, and cultural identity create disparities in access to water, food, and energy.

• These disparities occur within societies and between societies.

• Examples include inability to afford electricity, or privatization of water sources that excludes poorer groups.

• This means that sustainability must be judged not only by total resource supply, but also by fair distribution.

Operating scales of sustainability and justice

• Sustainability and environmental justice can be applied at different operating scales.

• ESS scales include: individual, business, community, city, country, and global.

• Examples:

  • Individual: transport, diet, consumption choices.

  • Business: supply chains, waste, resource efficiency.

  • Community: indigenous rights, shared land/water use.

  • Country: laws, taxes, energy policy.

  • Global: UN Sustainable Development Goals (SDGs) and climate agreements.

• Exam skill: be able to suggest how the same issue looks different at different scales.

Sustainability indicators

• Sustainability indicators are measurable variables used to assess whether a system is being used sustainably.

• Examples include biodiversity, pollution levels, human population trends, climate indicators, material footprints, and carbon footprints.

• These can be used from local to global scales.

• You may be asked to discuss one named environmental indicator and explain how it helps assess sustainability.

• Strong answers explain both usefulness and limitations.

Ecological footprint, carbon footprint, water footprint, biocapacity

• Ecological footprint = the area of land and water required to provide resources and absorb wastes for a given population at its current rate of consumption.

• If a population’s ecological footprint is greater than the area/resources available, this indicates unsustainability.

• Carbon footprint = total greenhouse gas emissions, usually measured in carbon dioxide equivalents.

• Water footprint = total water use, often expressed in cubic metres per year.

• Biocapacity = the ability of a biologically productive area to generate an ongoing supply of renewable resources and absorb wastes.

• Key relationship: unsustainability occurs when ecological footprint exceeds biocapacity.

• Students do not need calculation details, but must know what each footprint measures and how they are used in sustainability assessments.

Citizen science

• Citizen science helps monitor Earth systems and whether resources are being used sustainably.

• It contributes data relevant to local problems and can also feed into research on global issues such as climate change.

• ESS angle: citizen science increases participation, awareness, and data collection across large areas.

• Limitation: data quality can vary, so methods and protocols matter.

Sustainability frameworks and models: big picture

• ESS requires understanding that sustainability models are frameworks: they simplify reality to make complex issues easier to analyse.

• Because they are simplified, every model has both uses and limitations.

• For 1.3, the key models are:

  • UN Sustainable Development Goals (SDGs)

  • Planetary boundaries model

  • Doughnut economics model

  • Circular economy model

• Exam tip: for every model, be ready to explain what it helps us see and what it leaves out.

UN Sustainable Development Goals (SDGs)

• The SDGs are a set of global social and environmental goals and targets designed to guide action on sustainability and environmental justice.

• They address issues such as poverty, inequality, climate, environmental degradation, prosperity, peace, and justice.

• Uses:

  • provide a common global framework

  • support policy-making

  • apply to both developed and developing countries

  • encourage action on economic and social inequality

• Limitations:

  • may not go far enough

  • can be seen as top-down and bureaucratic

  • may ignore local context

  • depend on the quality of available data

Planetary boundaries model

• The planetary boundaries model identifies nine Earth-system processes that regulate the stability and resilience of the Earth system.

• It proposes that there are limits to human disturbance, and crossing them increases the risk of abrupt and irreversible change.

• Core idea: humanity should stay within a safe operating space.

• In exams, know that this model expands the conversation beyond climate change alone.

• Uses:

  • gives science-based limits for human pressure on Earth systems

  • highlights multiple Earth-system risks, not just climate

  • warns policymakers and the public about urgent action needed

• Limitations:

  • focuses mainly on ecological systems, not the human justice dimension

  • boundaries are a work in progress and may change with new data

  • global thresholds may be less useful for local decision-making

• You should be able to discuss which boundaries appear crossed and why.

This diagram maps the planetary boundaries and highlights which ones have been crossed. It is valuable for ESS because it visualizes the idea of a safe operating space for humanity and the risk of thresholds/tipping points. Source

Doughnut economics model

• The doughnut economics model aims for a regenerative and distributive economy that meets the needs of all people within the means of the planet.

• The inner ring = social foundation: below it, people lack essential needs.

• The outer ring = ecological ceiling: beyond it, humanity overshoots planetary limits.

• The goal is the safe and just space for humanity between the two rings.

• Regenerative = the economy works with and within living systems and helps restore them.

• Distributive = value and opportunity are shared more equitably among stakeholders.

• Uses:

  • includes both ecological and social dimensions

  • strongly supports environmental justice

  • can be applied at different scales: cities, countries, businesses, neighbourhoods

• Limitations:

  • still a developing model in practice

  • gives broad principles more than exact policies

Circular economy

• The circular economy aims to decouple economic activity from the consumption of finite resources.

• It contrasts with the linear economy: take–make–waste.

• Three core principles:

  • eliminate waste and pollution

  • circulate products and materials

  • regenerate nature

• ESS examples of benefits:

  • reduced waste

  • lower greenhouse gas emissions

  • longer product life cycles

  • stronger local food networks and communities

  • changing consumer habits

• Limitations:

  • low awareness among consumers and companies

  • weak regulation

  • some waste is not technically recyclable

  • implementation may be limited by finance

The butterfly diagram shows how biological and technical materials can circulate in a circular economy instead of becoming waste. It helps ESS students contrast linear and circular systems and identify where regeneration, reuse, repair, and recycling fit. Source

Fast exam links and common mistakes

• Link sustainability to resilience, tipping points, and long-term viability.

• Do not describe sustainability as only environmental: ESS always expects environmental + social + economic dimensions.

• Do not treat GDP as a sustainability indicator without criticism.

• Distinguish ecological footprint (human demand) from biocapacity (nature’s supply).

• For model-evaluation questions, always give both uses and limitations.

• For justice questions, always identify unequal impacts and unequal access to resources.

• When discussing sustainability, stronger answers refer to scale: local, national, and global.