In-Depth Notes on Environmental Systems and Societies

Enivronmental Systems and Societies Introduction

  • Environmental Systems and Societies SL: A guide designed for International Baccalaureate students, consolidating topics of environmental science into an accessible format.
  • Purpose: Provide revision material that is easy to follow and useful for students and teachers.
  • Approach: Step-by-step methodology to enhance understanding and skill development in environmental studies.

Systems and Models

  • Components of Systems:
    • Storages: Areas storing matter or energy (often represented as boxes).
    • Flows: Transfers or transformations between storages (indicated by arrows in diagrams).
    • Inputs and Outputs: Flows entering (inputs) or exiting (outputs) a system or storage.
    • Boundaries: Dividing lines that indicate the limits of a system.
  • Types of Systems:
    • Open System: Energy and matter flow in and out (e.g., ecosystems).
    • Closed System: Only energy flows in and out, matter remains constant (e.g., Earth as a whole).
    • Isolated System: Nothing flows in or out (theoretical concept).
  • Energy within Systems:
    • Governed by laws of thermodynamics:
    • 1st Law: Energy cannot be created or destroyed, only transformed.
    • 2nd Law: Entropy increases over time, meaning energy becomes less available.
    • Equilibrium: Systems often move towards stable equilibrium after disturbances, leading to new equilibria after tipping points.

Systems in the Natural World

  • Energy and Matter Flows:
    • Solar energy enters Earth (1400 W/m²) as short-wave radiation, re-radiated as long-wave radiation.
    • Much energy absorbed or reflected; only small percentage used by ecosystems (0.06% by plants via photosynthesis).
  • Biogeochemical Cycles:
    • Carbon Cycle: Movement of carbon through organisms, the atmosphere, and geological formations. Key transfers include photosynthesis and respiration.
    • Nitrogen Cycle: Involves nitrogen fixation and denitrification processes that shape ecosystem dynamics.
  • Biomes:
    • Defined by climatic conditions (temperature, precipitation), grouped in five major types (forests, grasslands, deserts, aquatic systems).
  • Ecosystems and Zonation:
    • Ecosystem Definition: Communities of organisms interacting with their environment.
    • Zonation: Variation in ecosystems along environmental gradients (latitude, altitude).

Investigating Ecosystems

  • Data Collection and Sampling Techniques:
    • General rules: Naming, extrapolation, and understanding limits of measurements.
    • Measuring Abiotic Factors: Using specific tools for temperature, salinity, and other variables.
    • Collecting and Identifying Organisms: Quadrats for non-motile organisms, traps for motile species, species abundance calculations based on capture methods.
  • Indices for Measuring Diversity:
    • Simpson Index: Assesses species diversity within a habitat.
  • Productivity Measures:
    • Gross primary productivity (GPP) and net primary productivity (NPP) represent energy captured by producers and energy available after losses.

Human Impact on the Biotic World

  • Biodiversity Value: Generally defined by habitat diversity, species richness, and genetic diversity. Higher diversity often indicates healthier ecosystems.
  • Human Activities Impacting Biodiversity: Habitat destruction, introduction of invasive species, pollution, and overharvesting significantly impact species extinction rates.

Water, Soil, and Food Production

  • Water Cycle: Describes concepts such as water storage, flows (evapotranspiration, runoff), and the impact of human activities on water availability.
  • Soil Importance: Essential for supporting ecosystems through nutrient cycling and supporting plant growth.
  • Sustainable Agricultural Practices: Addressing issues of soil erosion, conservation methods, and the need for sustainable food production systems.

Energy and the Atmosphere

  • Atmospheric Composition: Primarily nitrogen, oxygen, carbon dioxide, which influence climate and ecosystems. Changes can result from human activities (e.g., fossil fuel burning).
  • Pollution Effects: Photochemical smog, acid rain, and greenhouse gas emissions significantly affect ecosystems and human health.

Climate Change and Sustainability

  • Climate Change Drivers: Human activities, notably fossil fuel burning, contribute to disturbances in natural systems, leading to global warming and extreme weather events.
  • Mitigation and Adaptation Strategies: Necessary to combat impacts, including reducing emissions and promoting sustainable practices.
  • Sustainability Frameworks: Understanding how to manage energy resources and minimize human environmental impact through sustainable development practices.