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IB DP ESS — Topic 8: Human Populations and Urban Systems | SL & HL | Paper 1 & Paper 2
🎯 Learning Intentions By the end of this note, you will be able to:
- Define sustainable urban planning and ecological urban design using IB-aligned ESS terminology.
- Explain how urban systems function as socio-ecological systems and how urban growth generates environmental pressures at local, regional, and global scales.
- Describe the key features of sustainable urban design strategies, including green infrastructure, compact city design, transit-oriented development, and urban biodiversity corridors.
- Analyse the environmental, social, and economic trade-offs of different urban planning approaches using ESS analysis parameters: scale, sustainability, perspectives, and trade-offs.
- Evaluate the effectiveness of named case studies in achieving ecological and social sustainability goals in urban environments.
- Discuss contrasting worldviews — ecocentric, technocentric, and anthropocentric — in relation to urban planning decisions and the concept of the sustainable city.
- Construct a systems diagram showing feedback loops between urban growth, resource consumption, and environmental degradation.
Real-World Context & Relevance
In 2007, for the first time in human history, more than half of the world's population lived in urban areas. By 2023, that figure had risen to approximately 57%, and the United Nations projects that by 2050, nearly 70% of humanity — some 6.7 billion people — will be city dwellers (United Nations, Department of Economic and Social Affairs). This is not merely a demographic statistic. Cities currently consume roughly 75% of global primary energy, generate approximately 70% of global greenhouse gas emissions, and cover only about 3% of Earth's land surface. The concentration of people, energy flows, and material consumption in cities makes urban systems one of the most powerful levers — for better or worse — in the global sustainability transition.
The consequences of poorly planned urban growth are visible across the world. Jakarta, Indonesia, is sinking at rates of up to 25 centimetres per year in some districts, partly due to groundwater extraction driven by inadequate urban water infrastructure, while simultaneously facing increased flood risk from sea-level rise. In contrast, Curitiba, Brazil, developed in the 1970s under urban planner Jaime Lerner, pioneered a bus rapid transit system and integrated green space network that became a global model for sustainable urban design. The difference between these two trajectories is not simply wealth — it is planning philosophy, governance, and the degree to which ecological systems are treated as infrastructure rather than obstacles.
🌍 Why This Matters Urban planning decisions made today will lock in infrastructure, land use patterns, and energy systems for decades. Cities designed with ecological principles — permeable surfaces, urban forests, biodiversity corridors, and low-carbon transit — can simultaneously reduce greenhouse gas emissions, improve human health, enhance biodiversity, and build resilience to climate change. Cities designed without these principles amplify every major environmental crisis: climate change, biodiversity loss, freshwater scarcity, and air pollution.
Core Concepts & Definitions
To understand sustainable urban planning, we must first recognise what conventional urban development does to environmental systems. When natural land is converted to urban use, the landscape undergoes a fundamental transformation: permeable, biologically active surfaces are replaced by concrete, asphalt, and buildings.