Understanding the Anthropocene Epoch

Jan 24, 2025

Lecture Notes: The Anthropocene Epoch

Introduction to the Anthropocene

  • Definition: Proposed new epoch in geologic time where human activities rival or exceed natural forces in affecting Earth's systems.
    • Coined by Will Steffen.
    • "Anthro" = human, "scene" = epic.
  • Reflects significant human impact on the environment.
  • Focus of the course: How humans have altered major Earth systems (biosphere, hydrosphere, atmosphere, lithosphere, cryosphere).

Timing and Definition of the Anthropocene

  • Debate on when the Anthropocene began.
  • Geologic Time Measurements:
    • Hierarchy: Eons > Eras > Periods > Epochs.
    • Current placement: Cenozoic era, Quaternary Period.
    • Quaternary includes Pleistocene, Holocene, and debated Anthropocene.
  • Global Boundary Stratotype Section and Point (GSSP):
    • System to define geologic time since 1977.
    • Determined by International Commission on Stratigraphy and the Anthropocene Working Group (AWG).
    • Uses primary and secondary markers, well-preserved sections, and key events.

Human History and Environmental Impact

  • Human Evolution:
    • Hominids: First appeared ~6 million years ago.
    • Tool Making: Evidence in Kenya ~3.3 million years ago.
    • Homo habilis: Evolved ~2.5-2.8 million years ago during Pleistocene ice ages.
  • Human Colonization:
    • Spread across nearly all land surfaces.
    • Uncertainty in some regions like the Americas.
  • Animal Domestication and Agriculture:
    • Transition from hunters/gatherers to cultivators/keepers.
    • Allowed permanent settlements, increased population density, and cultural advancements.

Major Milestones in Human Development

  • Cultural and Economic Stages:
    • Paleolithic (hunters/gatherers), Neolithic Revolution, Bronze Age, Iron Age, Middle Ages.
  • Technological and Social Changes:
    • Early globalization (~1492).
    • Industrial Revolution ("Great Acceleration") began late 18th century.
    • 20th century population growth (1.5 to 6 billion).

Measuring Human Impact

  • Stratigraphic Markers:
    • Primary: E.g., fly ash from coal burning (Industrial Revolution).
    • Secondary: E.g., radionuclides from nuclear detonations starting 1945.
  • Proxy Data: Ice cores, fossil crop pollen, carbon isotopes, etc.
  • Percentage of Change: Rapid environmental changes post-Great Acceleration.

Anthropocene Working Group (AWG) Decision

  • Voted in May 2019 to formalize Anthropocene starting in 1950.
  • Awaiting ratification by International Union of Geological Sciences.

Discussion and Assignment

  • Discussion Points:
    • Agree or disagree with 1950 start date?
    • Consideration of human bias in determining epoch start.
    • Major debates within AWG.
  • Assignment:
    • Readings on eCampus.
    • One to two page paper due next Wednesday.
    • Use peer-reviewed articles, charts, graphs, and tables.
    • Citation styles: APA or MLA.
  • Podcast Recommendation: "Generation Anthropocene" episode "Earth in Human Hands" available on eCampus.