Ecosystem Disturbances

Types of Ecosystem Disturbances

Periodic Events

  • Occur with regularity.
  • Examples: rainy seasons, dry seasons.

Episodic Events

  • Occur less regularly but with some regularity based on environmental conditions.
  • Examples: hurricanes, forest fires.
  • More likely to occur when environmental conditions are right.

Random Events

  • Occur with no predictable pattern or reason.
  • Examples: asteroid strikes, volcanic eruptions.

Gradual Changes in Earth's Climate

  • Ecosystems can also be disrupted by slow, gradual changes in Earth's climate over time.
  • These climate changes are a result of the orbit that the Earth takes around the sun changing naturally over time.

Milankovitch Cycles

  • Variations in Earth's orbit.
  • These cycles happen with a regular frequency, they produce regular changes in Earth's climate as a result.
  • Unfold over tens of thousands of years.
  • Cause gradual climate change.
  • Important Note: Do not need to understand the intricacies of the Milankovitch cycles, but recognize how Earth’s climate changes naturally over time.

Three Types of Orbital Variations:

  1. Eccentricity: The shape of Earth's orbit around the Sun.
    • Sometimes brings Earth closer to the Sun, sometimes further away.
  2. Axial Precession: Wobbling of the Earth on its axis.
  3. Obliquity: Change in Earth's tilt.

Impact on Climate

  • Lining up the timing of Milankovitch cycles with ice core temperature data shows: Impact the temperature of Earth's climate by bringing it closer or further away from the sun or tilting the Northern Hemisphere closer or further away from the sun.
  • Earth's orbit brings Earth either closer or further away from the sun or tilts the Northern hemisphere closer or further away from the sun.

Sea Level Changes

  • Natural gradual cycling of climate change causes a change in sea level.
  • Data from the last 400,000 years shows a clear link between global temperature and sea level.
  • Warmer climates lead to sea level rise due to:
    • Melting of glacial and polar ice sheets.
    • Thermal expansion of water molecules in the ocean.

Ecosystem Disturbances

  • Low-lying coastal ecosystems (e.g., estuaries): May be completely flooded and disappear during periods of high sea level.
  • Shallow ocean waters (e.g., coral reef ecosystems): May become deeper; light may not penetrate to the bottom, changing the ecosystem.