IB^® Environmental Systems & Societies HL/SL

Environmental Systems & Societies (ESS) straddles the boundary between natural sciences (Group 4) and individuals & societies (Group 3). It studies how environmental systems work AND how human societies interact with, depend on, and impact them. Unlike pure biology or pure geography, ESS demands you weigh scientific evidence alongside values, perspectives, and ethics: exactly the kind of judgement examiners reward in evaluation questions.

A perspective is how an individual sees and understands a situation, shaped by values, beliefs, and assumptions. Perspectives:

• Are informed by sociocultural norms, scientific understanding, religion, economic conditions, lived experience, and global events.
• Drive choices and actions on environmental issues.
• Are not the same as arguments: arguments support or counter a perspective.

Worldviews are perspectives shared across groups, shaped by culture, philosophy, ideology, religion, and politics. With internet/social media, individuals are increasingly exposed to many worldviews at once.

Values are qualities or principles people consider important: honesty, freedom, security, equity, the intrinsic worth of nature, etc. They

• Shape priorities and judgements.
• Are individual but shared and shaped by community.
• Reveal themselves in communication and actions: what an organisation values shows up in its advertisements, policies, and practices.

Tension between values explains many environmental disputes: a logging company values economic gain; an indigenous community values ancestral land.

An EVS is a model showing the inputs that shape our perspectives (media, education, worldviews, lived experience) and the outputs that flow from them (judgements, choices, actions, advocacy). The IB groups EVS into three broad categories:

• Technocentric: believes technology and human ingenuity can solve environmental problems. Pro-growth, pro-innovation; favours geoengineering, nuclear, GM crops.
• Anthropocentric: places humans at the centre; nature has instrumental value (useful to us). Supports conservation when it serves human well-being. Often a "managerial" or "stewardship" stance.
• Ecocentric: sees nature as having intrinsic value independent of human use. Deep ecology, rewilding, land-ethic traditions. Some Indigenous and relational worldviews align with ecocentric or relational framings, but Indigenous perspectives are diverse and should not be treated as automatically ecocentric. May oppose any development in protected areas.

Real people are mixes of these, varying with context: categories are useful but imperfect.

The modern environmental movement has been shaped by:

• Individual activists: Wangari Maathai (Green Belt Movement), Greta Thunberg, Vandana Shiva.
• Authors / books: Rachel Carson, Silent Spring ($1962$); Aldo Leopold, A Sand County Almanac ($1949$).
• Media: An Inconvenient Truth ($2006$), Breaking Boundaries ($2021$), David Attenborough documentaries.
• Disasters: Minamata mercury poisoning ($1956$), Chernobyl ($1986$), Bhopal ($1984$), Deepwater Horizon ($2010$), Fukushima ($2011$).
• International agreements: Stockholm Conference ($1972$), Earth Summit/Rio ($1992$), Kyoto Protocol ($1997$), Paris Agreement ($2015$).
• Scientific discoveries: ozone hole ($1985$, Farman et al.), IPCC reports.
• New technologies: solar PV cost collapse, satellite earth observation.

A system is a set of interrelated components that function as a whole. Systems thinking is the foundational lens of ESS: environmental problems arise from interactions, not isolated parts.

• Storages (stocks): quantities of material/energy at a location (e.g., carbon in a forest, water in a lake).
• Flows (transfers / transformations): movement of material/energy between storages. Transfers keep matter the same form (water flowing in a river); transformations change it (photosynthesis: CO$_2 +$ H$_2$O → glucose).
• Inputs enter the system; outputs leave it.
• Boundaries are chosen by the analyst: drawing them differently changes the system.

• Open system: exchanges both matter and energy with surroundings. Most ecosystems (rainforest, lake) are open.
• Closed system: exchanges energy but not matter. The IB guide stresses that almost all systems are open: only the global biogeochemical cycles approximate closed systems, and Biosphere 2 is its example of a closed system. Earth as a whole is often described as approximately closed for matter (energy from the Sun in, infrared out; very little matter gained or lost).
• Isolated system: exchanges neither. Only theoretical (cannot exist on Earth).

Application: a Biosphere 2 experiment ($1991$) tried to be closed (matter) but allowed light in: failed when oxygen, food, and CO$_2$ went out of balance.

Steady-state equilibrium: stocks remain roughly constant despite continuous flows in and out (e.g., a mature forest). Most ecosystems sit in dynamic steady-states.

Feedback loops

• Negative feedback: a change triggers a process that counteracts it → stabilising. Example: predator–prey cycles; thermostat; sweat cooling the body.
• Positive feedback: a change triggers a process that amplifies it → destabilising. Example: ice-albedo feedback (warming melts ice → darker surface → absorbs more heat → more warming); permafrost thaw releasing CH$_4$.

Tipping points = thresholds beyond which positive feedback drives the system to a new state. Examples in climate: Amazon rainforest dieback (forest → savanna), West Antarctic ice sheet collapse, Atlantic Meridional Overturning Circulation (AMOC) shutdown.

A model is a simplified representation of a system used to understand it and predict behaviour. Examples: climate models, population models, food-web diagrams. Strengths: focus on key variables; can run "what-if" experiments; communicate complex ideas; cheap (vs real-world experiment).

Limitations

• Simplification: variables are omitted; assumptions may break down.
• Garbage in, garbage out: only as good as input data.
• Cannot fully capture emergent properties or chaotic behaviour.
• Models can give different answers: uncertainty is real (climate models project a range of warming).
• Difficult to validate for systems we have only one of (Earth's climate).

Sustainability = a measure of the extent to which practices allow for the long-term viability of a system: the responsible maintenance of socio-ecological systems so that there is no diminishment of conditions for future generations (guide 1.3.1). Environmental sustainability is the use and management of natural resources that allows their replacement and the recovery and regeneration of ecosystems (1.3.3). Sustainable development is a related but separate idea: development that meets the needs of the present without compromising the ability of future generations to meet their own needs (Brundtland Report, Our Common Future, $1987$; guide 1.3.6). Three pillars (the "triple bottom line"):

• Environmental: ecosystem health, biodiversity, climate stability.
• Social: human well-being, equity, education, health.
• Economic: long-run prosperity, livelihoods, fair distribution.

Sustainable yield: the rate at which a renewable resource can be harvested without depleting the stock: e.g., a forest harvested at the rate of regrowth.

$17$ goals adopted in $2015$, target year $2030$. Cover poverty, hunger, health, education, gender equality, water, energy, climate, life below water, life on land, peace and partnerships. Strengths: broad consensus; universal (rich and poor countries); integrated (recognises interlinkages: e.g., tackling poverty requires education AND climate action). Criticisms: $169$ targets are very ambitious; weakly enforced; some goals can conflict (rapid economic growth vs environmental targets). Progress is mixed and was set back by COVID-$19$ and conflict.

Ecological footprint = the area of land and water (in global hectares, gha) needed to provide the resources a population consumes and absorb the waste it produces. Biocapacity = what the planet can renewably supply. Earth Overshoot Day marks when humanity's demand exceeds Earth's annual biocapacity: the long-term trend is earlier (the date fluctuates year to year but has fallen from ~late December in the early 1970s to late July in recent years), signalling that we are using roughly 1.8 Earths of biocapacity each year (Global Footprint Network estimate for 2025, when Earth Overshoot Day fell on 24 July; the figure varies by year). National differences: USA $\sim 8$ gha/person; UK $\sim 4$; Bangladesh $\sim 0.8$; world fair share ≈ $1.6$ gha. Footprints reveal inequity in resource use.

Framework (Rockström et al., $2009$) identifying 9 Earth-system boundaries within which humanity can safely operate:

• Climate change.
• Biosphere integrity (biodiversity loss).
• Land-system change.
• Freshwater use.
• Biogeochemical flows (nitrogen and phosphorus).
• Ocean acidification.
• Atmospheric aerosol loading.
• Stratospheric ozone depletion.
• Novel entities (synthetic chemicals, plastics, persistent pollutants, and other human-created substances new to Earth systems; GMOs are sometimes discussed under this heading, but the core concern is novel chemicals and materials at scale).

Status (as of the 2023 update): 6 of 9 boundaries assessed as already crossed: climate, biosphere integrity, land-system change, biogeochemical flows, freshwater, and novel entities. The exact count depends on the assessment year and methodology, so cite "as of 2023" rather than presenting it as fixed.

Pollution = the addition of substances or energy to the environment at rates that exceed natural breakdown, causing harm.

Classifications

• Source: point (single identifiable, a factory pipe) vs non-point (diffuse, agricultural runoff).
• Form: organic (sewage) vs inorganic (heavy metals); biodegradable (food waste) vs persistent (plastics, DDT, PCBs).
• Persistence: Persistent Organic Pollutants (POPs): bioaccumulate (build up in organisms) and biomagnify (concentrate up food chains). Listed under the Stockholm Convention.

Pollution management strategies sit at three levels: prevent at the source, clean up during release, or restore ecosystems after damage. Prevention is cheapest; restoration is hardest.