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Aired: 5/12/2006
So you think global warming won't affect you? Wait until the great Atlantic Conveyor shuts down. And find out what's already happening in Alaska. In the last couple of decades, oceanographers have come to understand the central role the Gulf Stream plays in the enormous ocean currents that circle the globe. It brings a third of all the sun's heat that falls on the North Atlantic up to northern latitudes and, in the process, warms the northeast U.S., Europe and Scandinavia. Researchers at the Woods Hole Oceanographic Institution have found that in recent decades significant amounts of freshwater have been flowing into the Nordic Seas from the Arctic Ocean to the north that could potentially disrupt the operation of the Ocean Conveyor's recirculation pump, in turn reducing or even shutting down the flow of the Gulf Stream. Another group of researchers have found that the Russian Arctic rivers, which contribute two-thirds of all the freshwater that flows into the Ocean, have significantly increased their flow rates in recent decades -- the result of the higher precipitation that goes along with global warming. In Fairbanks, Alaska, the large glaciers in the mountain region that runs between southern Alaska and Canada have been melting and receding at an increasing pace, also in recent decades. Scientists have discovered several abrupt cooling events in the 12,000 years since the last Ice Age. One such event happened 8,200 years ago and may have been triggered when a huge lake of fresh water burst through the remains of ice sheets bordering Hudson Bay. The surge flooded down Hudson Strait and out into the path of the Gulf Stream. Ocean sediments show a cooling at the same time, all around the north Atlantic.