APES Unit 9.6 (Ocean Warming)

Atmospheric Warming ←→Ocean Warming

• As the atmosphere warms, heat is transferred to the ocean

  • Ocean absorbs heat radiated back to earth by greenhouse gases

  • Oceans absorb much of earth’s heat due to high specific heat of water (est. 90% of earth’s warming from past 50 yrs. occurred in oceans)

  • Thermohaline circ. distributes heat absorbed at surface to depths & other areas of earth

  • Heat absorbed by ocean can transfer back to atmosphere for decades

Effects on Marine Species

• Warmer water holds less O₂ causing resp. stress or suffocation

• Migratory routes and mating seasons can be altered, especially for whales

  • Reproduction timing, often tied to temp. change can be disrupted (fish esp.)

• Habitat loss: coral bleaching with heating ocean; shallow, sunny waters ideal for algae & coral become deper from ice melt

• Toxic algae blooms; toxic blue-green algae prefer warmer waters & warm temperature prevents mixing of water, enabling algae blooms

• Blue-green algae release toxins into the water that can kill marine species

  • Can also block sunlight & lead to hypoxia

Climate Change & Coral Reef

Coral Bleaching

• Coral reef = mutualistic relationship between coral & photosynthetic algae called zooxanthellae; algae supply sugar & coral supply CO₂ + detritus (nutrient containing org. matter)

  • Algae have narrow temp. tolerance and leave the reef when temp. rises 

  • Pollutants from runoff (sediment, pesticides, sunscreen) can also force algae from reef

  • Coral lose color & become stressed and vulnerable to disease without algae (main food source)