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Ocean Circulation

When you drop your message in a bottle in the ocean in San Francisco Bay, do you think it will ever reach your grand aunt in Oslo, Norway? The answer is yes, maybe, but it could take a few thousand years, so you?d be better off sending a postcard! The worlds oceans are all interconnected through several complicated processes that drive the planets winds and ocean currents. The global ocean circulation was simplified by scientists into what they call ?the great ocean conveyor?. The conveyor starts in the northern North-Atlantic of the coast of Greenland and northern Norway, where the water cools down so much that sea ice (link) forms in the winter. The ice formation leads to an increase in the surface waters density which causes them to sink all the way to the bottom. Now we track these waters on their journey when they first move southward through the entire Atlantic along the bottom all the way down to Antarctica. There the water might circle around Antarctica once or take a more direct path to the Pacific Ocean. On their way through the warm Pacific the waters get lighter until they rise to the surface in the North Pacific. Our mass of water already traveled a long way from the beginning of the trip from the sinking to the bottom of the cold and dark North-Atlantic until the rise to the surface in the Pacific. From there the journey continues to the Indian Ocean through a passage between the Asian and Australian continent. Next our water mass is likely to round the Cape of Good Hope in order to return as a surface current to the North Atlantic where the journey began around 10,000 years ago. So, if you were a fish that could live for thousands of years you could see the entire world by just floating along with the oceans currents. Luckily, if we want to see the world today we can get on an airplane and step off onto another continent within a few hours.