Glacial/Interglacial Periods and Volcanic Eruptions

Sea Level- Glacial/Interglacial Periods

• more glaciers = lower sea level
  • water that makes snow and eventually glaciers come from oceans
  • example:
  • 7.6 million miles of glaciers exist today → 230 foot rise in sea level if all of it melted
• Ice Age was 20,000 years ago
  • 3 times the amount of ice that is present today
  • sea level is 460 feet lower than it is today

Physical Earth-Based Factors: Volcanic Eruption

• flood basalts = largest eruptions on Earth
• erupts huge amount of lava over a “brief” )geologically speaking) time period
• bury large areas in lava
• gases emitted into the atmosphere
  • SO2 causes global cooling
  • CO2 causes global warming (longer term)
• ocean also absorb a lot of gases
  • change acidity and oxygen concentration
• example:
  • Siberian traps = 800,000 miles of lava covering 1.5 million miles in Siberia
  • coincides with the Permo-Triassic extinction (a major mass extinction)

Extraterrestrial-Based Factors

• Earth is constantly being bombarded with asteroids and (to a lesser extent) comets
• a meteoroid with a diameter of 6 miles could cause wildfires, acid rain, tsunami, and a dust cloud that could block out the sun for weeks to months