13   effects on oceans - updated
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13 effects on oceans - updated

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13   effects on oceans - updated 13 effects on oceans - updated Presentation Transcript

  • Climate Change Effects on Marine Systems
  • Effects on Marine Systems - Circulation
    • The “Achilles’ Heel” of the climate system.
  • Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
    • The Gulf Stream brings warm, salty water to the north – it’s an oceanic heat pump.
    • The loss of this heat would cool the North Atlantic region by 3-5° C.
    • A critical component of this is the sinking limb of the conveyor which is driven by density.
  • Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
    • The scientific community does not expect the conveyor to shut off as a result of global warming!
    • What is more likely is that existing Arctic ice will melt at a rate that buffers the warming at high latitudes.
    • But once that ice is gone …
  • Effects on Marine Systems - Circulation
    • Another circulation system that could be affected by global change is the El Niño – Southern Oscillation.
  • Effects on Marine Systems - Circulation
    • A typical El Niño event causes between 2 and 7 billion dollars in economic damage.
    • Usually due to some combination of drought, flooding, and storm damage.
  • Effects on Marine Systems - Circulation
    • Trade winds blowing from east to west pile up warm water in the western Pacific (Western Warm Pool). Pool of warm water generates a lot of precipitation for this region (Indonesia, Philippines, etc. )
  • Effects on Marine Systems - Circulation
    • Trade winds greatly weaken or even reverse direction allowing Warm Pool waters to “slosh” back towards the east.
  • Effects on Marine Systems - Circulation
    • First observed by South American fishermen – the anchovies would vanish around December.
  • Normal El Niño Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
    • Less intense hurricane season in the Atlantic.
    • More intense hurricane season in the Pacific.
  • Effects on Marine Systems - Circulation
    • Essentially an enhancement of “normal” conditions. Results in weather anomalies that are basically the opposite of those caused by El Niño.
  • La Ni ña Normal El Niño Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
  • Effects on Marine Systems - Circulation
    • El Niños used to occur every 4-7 years.
    • But since the early-1970’s they have occurred every 2-5 years.
    • A lot of research on whether that change in frequency is related to human impact on climate.
  • Effects on Marine Systems - Ecosystems
    • El Niños also have a strong effect on ecosystems.
    • Warm water where they are normally cooler cause organisms to move deeper to cooler temperatures.
    El Niño
  • Effects on Marine Systems - Ecosystems
    • Many fish move deeper, resulting in massive sea bird mortality during El Niño events due to starvation.
  • Effects on Marine Systems - Ecosystems http://video.nationalgeographic.com/video/player/environment/environment-natural-disasters/landslides-and-more/el-nino.html
  • Effects on Marine Systems - Ecosystems
    • Increased temperature (not just due to El Niño) a problem for many marine ecosystems.
    • Similar to freshwater ecosystems, warmer temperatures impact organism distribution, metabolism, and gender ratios.
    Effects on Marine Systems - Ecosystems
    • Temperature and coral reefs - “coral bleaching.”
    Effects on Marine Systems - Ecosystems
    • Temperature and coral reefs - “coral bleaching.”
    Effects on Marine Systems - Ecosystems
  • Effects on Marine Systems - Ecosystems
    • Corals are small animals that secrete a calcium carbonate skeleton.
    • Many coral species have symbiotic algae living in their tissue called zooxanthellae.
    Effects on Marine Systems - Ecosystems
    • Corals are small animals that secrete a calcium carbonate skeleton.
    • Many coral species have symbiotic algae living in their tissue called zooxanthellae.
  • Effects on Marine Systems - Ecosystems
    • Zooxanthellae produce organic compounds that the coral relies on for food.
    • When temperatures rise, the corals expel the zooxanthellae – makes them look white, or “bleached.”
  • Effects on Marine Systems - Ecosystems
    • Without the symbiotic zooxanthellae, the coral loses 90-95% of its food supply, and usually dies within months.
    • Once the coral is dead macro algae takes over, smothering the reef.
    Effects on Marine Systems - Ecosystems
  • Effects on Marine Systems - Ecosystems (green – no bleaching , blue – low bleaching , yellow – medium bleaching , red – high bleaching )
  • Effects on Marine Systems - Ecosystems
    • Temperature effects are expected to be greater for the Arctic.
  • Effects on Marine Systems - Ecosystems
    • Less sea ice means less area for seals to reproduce, less area for polar bears to hunt.
    • The other big concern is ocean acidification.
    • When CO 2 dissolves in water it produces carbonic acid – makes the oceans more acidic.
    Effects on Marine Systems - Ecosystems
    • Lots of organisms make their skeletons out of calcium carbonate.
    Effects on Marine Systems - Ecosystems
  • Effects on Marine Systems - Ecosystems
    • Will have drastic consequences not just on the carbonate organisms themselves, but all the way up the food chain that feeds on those organisms.
    Effects on Marine Systems - Ecosystems