Lecture on the Anthropocene

Introduction to the Anthropocene

• Definition: A proposed epoch in geologic time highlighting significant human impact on the natural environment.
• Coined by Will Steffen, "Anthropocene" stems from "anthro" (human) and "scene" (epoch).
• Describes human activities as profound drivers of change in Earth's systems.

Key Earth Systems Affected by Humans

• Biosphere
• Hydrosphere
• Atmosphere
• Lithosphere
• Cryosphere

Determining the Start of the Anthropocene

• Current Debate: Scientists are trying to pinpoint when human impact became significant enough to define a new epoch.
• Geologic Time Scale:
  • Humans are relatively recent, appearing in the Quaternary Period of the Cenozoic Era.
  • The Holocene Epoch and potentially the Anthropocene follow the Pleistocene Epoch.

Geologic Time Classification

• Global Boundary Status Type Section (GSSP):
  • Established in 1977 for consistent classification of geologic stages.
  • Defined by the International Commission on Stratigraphy, including the Anthropocene Working Group (AWG).
  • Utilizes primary and secondary markers to classify geological changes.

Human History and Environmental Impact

• Human Colonization:

  • Hominids appeared ~6 million years ago; Homo habilis around 2.5-2.8 million years ago.
  • Human spread across the Earth, with debated colonization dates for the Americas.

• Animal Domestication and Agriculture:

  • Transition from hunting-gathering to agriculture allowed permanent settlements.
  • Agricultural practices and animal domestication reduced the spatial needs for human sustenance.
  • Led to population density increases and cultural advancements.

Major Milestones in Human Advancement

• Technological and Social Developments:
  • Paleolithic (hunters-gatherers), Neolithic Revolution, Bronze Age, Iron Age.
  • Middle Ages marked significant human population expansion.

Measuring Human Impact

• World Population Growth: Logarithmic scale highlights rapid expansion through technological innovation.
• Stages: Agricultural revolution, early globalization (post-1492), Industrial Revolution ("Great Acceleration").
• Indicators:
  • Stratigraphic markers measure human impact.
  • Coal burning fly ash for Industrial Revolution; radionuclides for nuclear detonations.

Scientific Measurement Tools

• Proxy Data: Ice cores, fossil crop pollen, temperature changes, CO2 levels, methane, radioactive isotopes, industrial chemicals.
• Impact Representation: Changes in biosphere, hydrosphere, atmosphere since assumed zero human impact 10,000 years ago.

Recent Developments

• May 2019: AWG voted to formalize the Anthropocene, suggesting a start in 1950.
• Next Steps: Awaiting ratification by the International Union of Geological Sciences' Executive Committee.

Discussion Points

• Is 1950 the correct starting point for the Anthropocene?
• Role of human bias in epoch determination.
• Key debates within the Anthropocene Working Group.

Assignment 1 Instructions

• Due: Next Wednesday.
• Requirements:
  • One to two-page paper, single-spaced, 12-point Arial font.
  • Use APA or MLA citation style.
  • Include scientific charts, graphs, and tables.
• Resources: Readings on eCampus and the podcast "Generation Anthropocene".