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