Ocean Salinity & Density Currents Class Copy Ocean Salinity Oceans are salty



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E. The now-warmed surface waters continue circulating around the globe. They eventually return to the North Atlantic where the cycle begins again.

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How much water moves because of the Global Conveyor Belt?

The conveyor belt moves at much slower speeds (a few centimeters per second) than wind-driven or tidal currents (tens to hundreds of centimeters per second). It is estimated that any given cubic meter of water takes about 1,000 years to complete the journey along the global conveyor belt. In addition, the conveyor moves an immense volume of water—more than 100 times the flow of the Amazon River .



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Climate and the Global Conveyor Belt

The global conveyor belt is a strong, but easily disrupted process. If global warming results in increased rainfall in the North Atlantic, and the melting of glaciers and sea ice, the influx of warm freshwater onto the sea surface could block the formation of sea ice, disrupting the sinking of cold, salty water. This sequence of events could slow or even stop the conveyor belt, which could result in potentially drastic temperature changes in Europe.


Phytoplankton and the Global Conveyor Belt

The conveyor belt is also an extremely important component of the global ocean nutrient cycle and carbon dioxide cycle. Warm surface waters have their nutrients and carbon dioxide used up by microscopic plants, phytoplankton. These waters are “recharged” (enriched again) as they travel through the conveyor belt’s deep or bottom layers. The world’s food chain depends on the cool, nutrient-rich waters that support the growth of algae and seaweed.



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Adapted from

DataStreme Ocean

American Meteorological Society.

Mark Schwartz. Stanford Report, April 24, 2002

NASA (National Aeronautics and Space Administration)


2000 Case Study from NOAA (National Oceanic and Atmospheric Administration)
This reading highlights the how on oceans interact globally!
Sea ice forms, grows, and melts in the ocean. It forms in the polar oceans, the Arctic the Antarctic Oceans. In the Arctic, there is a permanent mass of ice covering the region. Nearly all of the Southern Ocean or Antarctic sea ice is "seasonal ice," or it melts away and reforms annually. Arctic and Antarctic ice is of vital importance to the marine mammals and birds for which it is a habitat.
Even though sea ice occurs primarily in the polar regions, it influences the climate of the entire globe. Sea ice is important because it regulates exchanges of heat, moisture and salinity in the polar oceans. It also can influence the success of an ecosystem.
In March 2000 (the summer season in the Antarctic), the largest iceberg ever recorded broke off Antarctica's Ross Ice Shelf. Roughly the size of Connecticut, the massive berg eventually fractured into smaller pieces which blocked the normal flow of pack ice out of the Ross Sea.
As a result, large stretches of normally open ocean were covered with pack ice from November 2000 to March 2001. During these crucial spring and summer months, the Ross Sea usually teems with life, as tons of microscopic marine algae -- called phytoplankton -- undergo reproductive blooms.
Phytoplankton need open water to reproduce, but the abnormally high levels of pack ice caused a 40 percent decline in plankton productivity. Sea ice is very effective at blocking light, so the phytoplankton couldn't grow -- there was just too much ice around.
The Ross Sea ecosystem depends on phytoplankton -- a primary food source for shrimp-like krill, which in turn are consumed by fish, seals, whales and penguins.

The 40 percent drop in phytoplankton, affected the entire food chain -- from krill to penguins. Penguins suffered breeding losses because of the lack of food; they had to go much farther to feed and their nests were exposed for longer periods of time to predators.

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