Earth's Atmosphere Evolution

Introduction

• Video Topic: Evolution of Earth's atmosphere
• Current Composition: ~80% Nitrogen, ~20% Oxygen, <1% other gases (CO2, water vapor, noble gases)
• Theory Basis: Supported by evidence, evolutionary process over 4.6 billion years

Early Earth's Atmosphere

• First Billion Years: Dry Earth with intense volcanic activity
  • Produced gases: Carbon Dioxide (CO2), Water Vapor, Nitrogen, Methane, Ammonia
  • Early atmosphere primarily CO2, similar to Mars and Venus today
• Water Condensation: Formation of oceans
  • CO2 dissolved in oceans
  • Formation of carbon precipitates and sediments on seabed

Photosynthesis and Atmospheric Shift

• 2.7 Billion Years Ago: Emergence of algae
• Evolution of Green Plants: Facilitated rapid changes
• Photosynthesis: Crucial process
  • Equation: Consumes CO2, produces Oxygen (O2)
  • Result: Decline in CO2, rise in O2 over billions of years
  • Enabled evolution of complex life (e.g., animals)

Carbon Sequestration

• Algae and Plant Death: Deposits of organic material on seabed
• Formation of Sedimentary Rock: Compression over millions of years
  • Types of Formations:
    • Crude Oil & Natural Gas: From dead plankton
    • Coal: From thick deposits of dead plant material
    • Limestone: Comprised mainly of calcium carbonate from marine organisms

Recap Summary

• Volcanic Activity: Produced a CO2-rich atmosphere
• Ocean Formation: CO2 dissolved, formed sediments
• Algae and Plants: Photosynthesis decreased CO2, increased O2
• Present Atmosphere: Mainly oxygen and nitrogen
• Sedimentary Rock & Fossil Fuels: Result of dead organic matter

Conclusion

• Overall Understanding: Evolution from a CO2-rich atmosphere to a balanced one with nitrogen and oxygen
• Video End Note: Recap of major events leading to current atmospheric conditions