Unit 4: How Can We Live Sustainably?
Core concepts
Unit 4 applies ecological understanding to human use of resources and sustainability. You must understand renewable and non-renewable resources, energy sources and their environmental impacts, waste management (reduce, reuse, recycle, recovery, disposal), pollution (air, water, soil, including eutrophication and acid deposition), and sustainable development. Study ecological footprints, carrying capacity for human populations, life-cycle analysis, and environmental management tools such as legislation, market mechanisms, education and treaties. Understand how to evaluate trade-offs between economic, social and environmental factors, and how to interpret data on resource use, emissions and pollution trends.
Traps
Students often treat renewable as automatically sustainable; a renewable resource can be overharvested. Another trap is confusing pollution with waste, or assuming dilution solves pollution. In evaluation questions, weak answers list impacts without weighing trade-offs or considering scale and time. Be careful with units and percentage-change calculations.
Worked example / rule of thumb
Percentage change = ((new − old) / old) × 100. If emissions fall from 80 to 60 units, change = ((60 − 80) / 80) × 100 = −25%. Rule of thumb: for any sustainability question, address environmental, economic and social dimensions and identify who bears the costs and benefits.