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Sustainability Overview

Oct 19, 2025

Overview

This lecture introduces the concept of sustainability, its core definition, and frameworks for understanding how resource use impacts current and future generations.

Definition of Sustainability

  • Sustainability is meeting present needs without compromising future generations' ability to meet their needs.
  • The U.N. Brundtland Commission popularized this definition of sustainable development.
  • Sustainability focuses on living today so that future generations can thrive.

Resource Use and Equilibrium

  • Many planet resources (e.g., trees, fish) can replenish if used at the right rate (replacement rate).
  • Replacement rate is the pace at which resources can naturally recover after use.
  • Using resources at the same rate they replenish keeps them at equilibrium.
  • Overusing resources depletes them, leading to issues such as disappearing fisheries and forests.
  • Excessive consumption causes problems like climate change and ocean plastics.

Systems Thinking in Sustainability

  • Sustainability requires understanding how individual actions affect global systems.
  • Every decision, like buying a smartphone, has worldwide impacts, including on resource extraction and people.

The Three E’s Framework (Triple Bottom Line)

  • Sustainability involves three interconnected pillars: environment, economy, and equity.
  • Focusing only on short-term economic profit undermines long-term economic health.
  • Protecting the environment without considering livelihoods can harm society.
  • Ignoring equity leads to unequal resource distribution and social problems.
  • Successful sustainability requires balancing and connecting all three E’s.

Key Terms & Definitions

  • Sustainability — using resources in a way that does not harm future generations’ ability to do the same.
  • Replacement Rate — the rate at which a resource can naturally replenish after being used.
  • Equilibrium — a state where resource use matches the rate of resource replenishment.
  • Triple Bottom Line (Three E’s) — framework emphasizing environment, economy, and equity in sustainable decision-making.
  • Systems Thinking — analyzing the complex connections between decisions, resources, and global impacts.

Action Items / Next Steps

  • Review the definition of sustainability and the three E’s framework.
  • Reflect on personal consumption habits and their global impacts.