Great Oxidation Event

Definition

The Great Oxidation Event (GOE) was a significant increase in Earth's atmospheric oxygen levels, occurring approximately 2.4 billion years ago, which marked a turning point in Earth's history and influenced the emergence of complex life. This event transformed the planet's environment, allowing for new forms of life to evolve and thrive, and was largely driven by the photosynthetic activity of cyanobacteria, which released oxygen as a byproduct.

5 Must Know Facts For Your Next Test

1. The Great Oxidation Event led to atmospheric oxygen levels rising from less than 0.1% to about 1% and eventually to over 20% over billions of years.
2. Prior to the GOE, most life on Earth was anaerobic, meaning it did not require oxygen, and was primarily unicellular.
3. The accumulation of oxygen during this period resulted in the formation of ozone (O3), which protects the Earth from harmful ultraviolet radiation.
4. Banded Iron Formations provide geological evidence of the Great Oxidation Event, showcasing how iron oxides precipitated out as oxygen levels increased.
5. The GOE set the stage for future evolutionary developments, including the emergence of multicellular organisms and complex ecosystems.

Review Questions

• How did the Great Oxidation Event influence the types of life that could exist on Earth?
  • The Great Oxidation Event dramatically changed Earth's atmosphere by increasing oxygen levels, which allowed for aerobic organisms to thrive. Before this event, anaerobic organisms dominated due to the lack of oxygen. As oxygen became more abundant, it enabled the evolution of more complex life forms that rely on aerobic respiration, leading to diverse ecosystems and paving the way for multicellular life.
• What role did cyanobacteria play during the Great Oxidation Event and how did their activity impact Earth's geology?
  • Cyanobacteria were essential during the Great Oxidation Event as they performed photosynthesis, releasing oxygen as a byproduct into the atmosphere and oceans. Their proliferation increased atmospheric oxygen levels significantly, which led to geological changes such as the formation of Banded Iron Formations. These formations indicate periods when free oxygen was present in water, illustrating how cyanobacteria fundamentally altered Earth's chemistry.
• Evaluate the long-term implications of the Great Oxidation Event on Earth's biosphere and how it contributed to subsequent evolutionary milestones.
  • The long-term implications of the Great Oxidation Event were profound, as it not only transformed Earth's atmosphere but also set in motion critical evolutionary milestones. The rise in oxygen levels allowed for aerobic metabolism to become prevalent, enabling complex multicellular organisms to evolve. This shift laid the foundation for future biodiversity and ecological complexity, ultimately shaping the course of evolution on Earth and leading to significant life forms such as plants, animals, and fungi.

Related terms

Cyanobacteria: Microorganisms that are capable of photosynthesis and played a crucial role in producing oxygen during the Great Oxidation Event.

Anaerobic organisms: Organisms that thrive in environments devoid of oxygen, which were prevalent before the Great Oxidation Event.

Banded Iron Formations:

Sedimentary rocks that formed from iron-rich sediments during the GOE, indicating the presence of free oxygen in the oceans.