Snowball earth

Definition

Snowball Earth refers to a hypothesis that suggests the Earth was once entirely or nearly entirely frozen over, covering the planet in ice during periods in the late Proterozoic Eon, particularly around 720 to 635 million years ago. This event is significant as it highlights dramatic shifts in Earth's climate and has implications for the evolution of life and geological processes during this period.

5 Must Know Facts For Your Next Test

1. The Snowball Earth hypothesis suggests that the planet was covered in ice from pole to pole, potentially reaching temperatures as low as -50 degrees Celsius in some regions.
2. This global glaciation is believed to have been interrupted by volcanic activity, which released greenhouse gases like CO2, leading to a gradual warming and eventual thawing of the planet.
3. Evidence for Snowball Earth includes glacial deposits found in tropical regions, indicating that ice sheets extended far beyond current polar areas.
4. The Snowball Earth events are thought to have had profound effects on the evolution of life, paving the way for the emergence of complex multicellular organisms in the subsequent Ediacaran Period.
5. The duration of these extreme glacial periods is debated, but they may have lasted millions of years, significantly impacting Earth's climate and biosphere.

Review Questions

• How did the Snowball Earth hypothesis contribute to our understanding of Earth's climatic history?
  • The Snowball Earth hypothesis has played a crucial role in understanding Earth's climatic history by illustrating extreme climate variations that have occurred over geological time. It reveals how global cooling can lead to widespread glaciation and how such events can dramatically alter the environment. Additionally, it highlights the potential for volcanic activity to contribute to climate change by releasing greenhouse gases, allowing scientists to better comprehend feedback mechanisms within Earth's climate system.
• Discuss the relationship between Snowball Earth and the evolution of early multicellular life during the Ediacaran Period.
  • Snowball Earth is believed to have set the stage for significant evolutionary changes leading into the Ediacaran Period. As the planet thawed from its icy state, new ecological niches were created, allowing for greater biodiversity and the emergence of complex multicellular organisms. This transition likely facilitated interactions among species and sparked evolutionary innovations, laying the groundwork for life forms that would dominate during the Cambrian explosion.
• Evaluate the evidence supporting the Snowball Earth hypothesis and its implications for understanding modern climate change.
  • The evidence supporting the Snowball Earth hypothesis includes geological records such as tillites and glacial striations found in tropical locations, suggesting extensive glaciation. The implications for understanding modern climate change are profound; they highlight how quickly climate can shift under certain conditions and stress the importance of greenhouse gas concentrations. By studying past extreme climate events like Snowball Earth, scientists can gain insights into potential future scenarios under human-induced climate change, emphasizing the interconnectedness of Earth's systems.

Related terms

Cryogenian Period: The Cryogenian Period is a geological time frame that lasted from about 720 to 635 million years ago, marked by extensive glaciation events, including the Snowball Earth hypothesis.

Glacial Intervals: Glacial intervals are periods in Earth's history characterized by significant cooling and the expansion of ice sheets and glaciers, often correlating with mass extinction events.

Ediacaran Biota: The Ediacaran biota refers to an assemblage of early multicellular organisms that lived before the Cambrian explosion, possibly influenced by climatic changes during Snowball Earth.