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How a person sees an issue, shaped by their values and experiences.
Environmental value system (EVS)
A worldview that shapes how an individual or society perceives and evaluates environmental issues.
Ecocentric
Nature-centred: nature has intrinsic value; favours self-restraint and small-scale, local solutions.
Anthropocentric
Human-centred: humans manage the environment sustainably through policy, taxes and regulation.
Technocentric
Technology-centred: human ingenuity and technology will solve environmental problems.
An EVS is a system: inputs (education, culture, religion, media, family, economics) are processed into outputs (decisions, actions, lifestyle).
The spectrum runs from deep ecologists and self-reliance soft ecologists (ecocentric) through environmental managers (anthropocentric) to cornucopians (technocentric).
Historical events shaped environmental thinking: Rachel Carson's Silent Spring (1962, pesticides), the Minamata disease case, the Chernobyl disaster (1986), the Rio Earth Summit (1992), the Paris Agreement (2015).
Perspectives differ between individuals, societies and generations: indigenous societies, for example, often see people as part of nature rather than its managers.
Compare how an ecocentrist and a technocentrist might respond to a shortage of fresh water.
Ecocentrist: reduce demand by using less water, protect rivers and wetlands, use local small-scale solutions such as rainwater harvesting.
Technocentrist: increase supply with desalination plants, large dams and water recycling technology.
An anthropocentrist would mix the two through regulation and water pricing.
Exam tip: In evaluation questions, show how different EVSs lead to different responses to the same issue, then justify which is most appropriate in context.
1.2Systems
Key terms
System
A set of interrelated parts (storages) connected by flows of energy and matter.
Open / closed / isolated system
Exchanges energy and matter / energy only / neither.
Transfer vs. transformation
A flow that changes location / a flow that changes form or state.
Negative feedback
Counteracts change and brings the system back to equilibrium (stabilising).
Positive feedback
Amplifies change and pushes the system away from equilibrium (destabilising).
Tipping point
A critical threshold beyond which a system shifts to a new state, often irreversibly.
Models simplify reality (diagrams, equations, computer simulations). They help to understand and predict, but leave out detail and may give unreliable predictions.
Transfers: e.g. water flowing in a river. Transformations: e.g. evaporation (liquid → gas), photosynthesis (light → chemical energy).
Equilibrium: steady-state (fluctuates around a constant average, e.g. a mature forest) or static (no change). Systems are resilient if they can absorb disturbance.
Negative feedback example: more prey → more predators → fewer prey. Positive feedback example: warming melts ice → lower albedo → more warming.
Systems can be studied at many scales, from a drop of pond water to the whole biosphere (the Gaia hypothesis treats Earth as one self-regulating system).
HLResilience depends on diversity, size of storages, rate of reproduction and the scale of disturbance. Crossing a tipping point can cause a regime shift, e.g. coral reef → algae-dominated reef.
Worked example
Explain how melting Arctic sea ice is an example of positive feedback.
Environmental Impact Assessment (EIA): studies the likely effects of a development before it is approved, and proposes mitigation.
The UN Sustainable Development Goals (SDGs, 2015) set 17 global targets for 2030.
EF vs. biocapacity: if a population's footprint is larger than the biocapacity of its area, it is living unsustainably (ecological deficit).
Planetary boundaries include climate change, biosphere integrity, land-system change, freshwater use, biogeochemical flows (N and P), ocean acidification, atmospheric aerosols, ozone depletion and novel entities. Several have already been crossed.
HLCircular economy: design out waste, keep products and materials in use, regenerate natural systems. Contrast with the linear “take–make–dispose” economy.
Worked example
A country's ecological footprint is 5.2 global hectares per person and its biocapacity is 2.1 gha per person. Comment.
EF > biocapacity, so there is an ecological deficit of 3.1 gha per person.
The country uses more resources and produces more waste than its land and water can sustainably support.
It depends on imports and on the global commons (e.g. the atmosphere absorbing its CO₂).
Exam tip: Define sustainability in terms of rates: using natural capital no faster than it regenerates. Vague answers like “protecting nature” score little.
HL.aHL lens: environmental law HL
Key terms
Environmental law
Rules that regulate human interaction with the environment.
International agreement
A treaty between countries, e.g. the Montreal Protocol or the Paris Agreement.
Polluter pays principle
Those who cause pollution should bear the cost of managing it.
Rights of nature
Legal recognition that ecosystems (e.g. rivers) have rights.
Law operates at different levels: international (treaties, conventions), national (legislation), local (planning regulations) and through courts.
International law depends on agreement and enforcement: countries can refuse to sign or withdraw, and enforcement is often weak.
Successful example: the Montreal Protocol (1987) phased out most ozone-depleting substances. Less successful: early climate agreements without binding targets.
Rights of nature: e.g. the Whanganui River in New Zealand was given legal personhood (2017).
Laws reflect the EVS of the society that makes them.
Worked example
Why was the Montreal Protocol more successful than many climate agreements?
Few substances and industries were involved, and substitutes were available.
The risk (ozone hole, skin cancer) was clear and measurable.
Climate change involves almost every economic activity, so agreement and enforcement are much harder.
Exam tip: Use real treaties as evidence and evaluate them: who signed, what was binding, and whether targets were met.
HL.bHL lens: environmental economics HL
Key terms
Externality
A cost or benefit that affects a third party not involved in a transaction.
Market failure
When markets fail to allocate resources efficiently, e.g. by ignoring environmental damage.
Tragedy of the commons
Overuse of a shared resource because each individual benefits from using more.
Carbon tax / cap-and-trade
A tax per tonne of CO₂ / a limit on total emissions with tradable permits.
Natural capital valuation
Putting a monetary value on ecosystem services.
Pollution is a negative externality: the market price does not include the environmental cost.
Market-based tools: carbon taxes, cap-and-trade (emissions trading), subsidies for green technology, payments for ecosystem services.
Regulation: standards, bans, quotas.
Valuing ecosystem services helps decision-makers compare options, but many values (cultural, intrinsic) are hard to price.
GDP ignores environmental damage; alternatives include “green GDP” and wellbeing indicators.
Worked example
Explain how a carbon tax could reduce emissions.
It raises the price of fossil fuels in proportion to their CO₂ emissions.
Firms and consumers switch to cleaner options or use less energy.
The polluter pays, and revenue can fund green investment; but it may hit low-income households hardest.
Exam tip: Compare market tools with regulation: which is more effective, fairer and easier to enforce in the case given?
HL.cHL lens: environmental ethics HL
Key terms
Environmental ethics
The study of the moral relationship between humans and the environment.
Intrinsic value
Value in itself, regardless of usefulness to humans.
Instrumental value
Value because it is useful to humans.
Environmental justice
Fair distribution of environmental benefits and harms between people.
Intergenerational equity
Fairness between present and future generations.
Ethical frameworks: anthropocentric (only humans have moral status), biocentric (all living things), ecocentric (whole ecosystems).
Approaches: consequentialist (judge by outcomes), deontological (duties and rights), virtue ethics (what a good person would do).
Environmental justice: poorer and marginalised communities often suffer most from pollution and climate change, while contributing least.
Ethical questions: Should we save species with no economic value? Who should pay for climate adaptation? Do future generations have rights?
Worked example
Use an ethical argument to discuss whether high-income countries should pay for climate adaptation in low-income countries.
Justice: high-income countries emitted most historical CO₂, while low-income countries suffer many of the impacts.
Counter-argument: present citizens did not cause past emissions; emerging economies now emit a lot too.
Judgment: a shared but differentiated responsibility, as in the Paris Agreement.
Exam tip: Name the ethical position you are using; it makes your evaluation explicit and earns analysis marks.