30 Sep Sustainable Practices in IB ESS: Systems and Trade-offs
Sustainable practices in IB ESS should be evaluated through their environmental, social and economic consequences. A label such as “natural”, “traditional” or “green” does not establish that a practice is sustainable. Ask what changes, who benefits, who bears costs and over what timescale.
Environmental systems are dynamic
Ecosystems exchange matter and energy with their surroundings and respond to disturbances. Nutrients can cycle, but energy flows through the system and is dissipated as heat. Ecosystems are not always in a fixed balance, and resilience has limits.
Use a system diagram to identify relevant stores, inputs, outputs and interactions. State the boundary: a farm-level improvement may still involve impacts elsewhere through fertilizer production or land-use change.
Manage nutrients rather than assuming compost is harmless
Compost can return organic material and nutrients to soil, but application must suit soil conditions and crop needs. Excess nitrogen and phosphorus can reach waterways from organic materials as well as synthetic fertilizers. The US EPA identifies manure and chemical fertilizers as potential sources of nutrient pollution when nutrients are not fully used by plants.
Evaluate application rates, timing, runoff pathways and water-quality evidence. Pesticide toxicity and nutrient enrichment are different pollution mechanisms; do not describe every agricultural chemical as causing eutrophication.
Biodiversity can support resilience, but cannot guarantee it
Different species and genetic variation can support ecosystem functions and responses to changing conditions. However, a diverse ecosystem can still be damaged by severe drought, disease, warming or habitat loss. The CBD review of forest resilience, biodiversity and climate change examines these relationships and their limits.
A mixed-crop system may offer benefits, but assess actual yields, soil conditions, pest pressure, water use and labour. No single design is best for every location.
Traditional agriculture is not automatically emission-free
Using less machinery may reduce fuel-related emissions, but food production can still release greenhouse gases through biological processes and land-use changes. For example, flooded rice cultivation can produce methane, and nitrogen inputs can contribute to nitrous oxide emissions. These processes are covered in the IPCC assessment of agriculture and land use.
Circular economy: check the whole system
Reducing unnecessary consumption, maintaining products, reusing materials and recycling can reduce resource demand and waste. Circular systems still require energy and can involve material losses. Compare repairability, collection, processing and what happens at the end of a product’s life rather than claiming that waste disappears.
Original evaluation exercise
This is an original practice task, not a marked IB response. Compare two nutrient-management plans for a farm. What information would you need about runoff, crop yield, costs and farmers’ constraints? Explain one potential benefit, one limitation and how the conclusion depends on local evidence.
Continue with environmental management strategies and practise a balanced judgment relevant to your SL or HL question.
Practise with individual ESS support
In Marija’s online IB ESS SL and HL lessons, you can work on concepts, data interpretation and clear explanations. Request a free 20-minute trial lesson to discuss your priorities. For IA work, the investigation and submitted writing remain your own.
Course reference: Official IB ESS guide, first assessment 2026 and IB course updates. Reviewed 7 October 2026.
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