APES 9.6 Ocean Warming

Relationship Between Atmospheric and Oceanic Warming

  • Two-way Relationship:

  • The atmosphere warms the ocean.

  • The ocean radiates heat back to the atmosphere.

  • Greenhouse Effect:

  • Greenhouse gases capture heat from Earth's surface, leading to ocean heating.

  • Heat Absorption:

  • Oceans absorb up to 90% of excess heat resulting from greenhouse gases.

  • Specific Heat of Water:

  • Water has a high specific heat, allowing it to store excess heat effectively.

  • Important for regulating Earth's climate.

Thermohaline Circulation

  • Heat Distribution:

  • Thermohaline circulation mixes heat throughout the ocean.

  • Example: Gulf Stream distributes heat to Europe.

  • Long-term Heat Release:

  • Oceans hold heat for decades; if greenhouse gas concentrations stop increasing, atmospheric warming continues due to ocean heat release.

Effects of Ocean Warming on Marine Life

  • Dissolved Oxygen Levels:

  • Warmer water holds less oxygen, affecting fish and marine mammals.

  • Can lead to respiratory stress or suffocation.

  • Altered Migratory Patterns:

  • Ocean temperature changes can disrupt migratory routes and breeding seasons.

  • Earlier migration can lead to mismatches in food sources.

  • Habitat Loss:

  • Coral bleaching due to increased temperatures and water depth changes.

  • Melting polar ice reduces shallow, warm waters crucial for coral ecosystems.

  • Algae Blooms:

  • Warmer waters lead to toxic blue-green algae growth.

  • Algae can choke aquatic plants and deplete oxygen, causing hypoxic conditions.

  • Algae blooms reduce sunlight penetration, impacting photosynthesis.

Coral Reef Ecosystems

  • Biodiversity Importance:

  • Coral reefs are rich in biodiversity, providing habitat and food sources.

  • They are also significant for eco-tourism.

  • Climate Change Effects:

    • Thermal Stress: Causes stress to coral and associated organisms.

    • Coral Bleaching: Loss of mutualistic algae (zooxanthellae) results in coral losing color and energy.

    • Sedimentation: Increased sedimentation can smother corals and block sunlight.

    • Altered Storm Patterns: Stronger storms physically damage reefs and disrupt the ecosystem.

    • Changes in Precipitation: Can affect salinity levels, impacting marine life.

    • Altered Ocean Currents: Changes in currents can disrupt nutrient flow and habitat.

  • Ocean Acidification:

    • Decreased pH threatens coral structure and survival.

Coral Bleaching

  • Definition of Coral Ecosystem:

  • Characterized by symbiotic relationship between coral polyps and zooxanthellae algae.

  • Bleaching Process:

    • Coral expels zooxanthellae due to temperature rise; leads to loss of color.

    • Bleached corals are not dead but are severely stressed and vulnerable.

  • Impact of Pollutants:

    • Land-based pollutants can also cause algae to leave the coral.

    • Remember: bleached corals remain alive but have a reduced energy source.

  • Possibility of Recovery:

    • If conditions improve, zooxanthellae can return, allowing corals a chance to recover.