Reduction in Deep Sea Current
This is the VOA Special English SCIENCE REPORT.
Scientists say there has been a reduction in the flow of a deep sea current during the past fifty years. The current of extremely cold water comes from the Arctic Ocean. It enters the Atlantic Ocean between Iceland and Greenland.
Bogi Hansen is a scientist for the Faroese Fisheries Laboratory in the city of Torshavn in the Faroe Islands. He led a team of researchers from Norway, Scotland and the Faroe Islands. They measured the current in an area of sea between the Faroe Islands and Scotland. There is a large piece of earth about five-hundred meters below the surface there. The coldest, saltiest water does not flow over this ridge. The water is too heavy. It sinks to deeper levels along the side of the ridge.
However, there is a place on the ridge that drops to more than eight-hundred meters below the surface. Cold, heavy, deep water flows through the ridge and into the Atlantic Ocean. Then the water drops thousands of meters to the sea bottom.
The researchers began measuring the flow through the opening in the ridge in Nineteen-Ninety-Five. They found the water flow decreased by two to four percent each year. They used other methods of measurement to estimate the decrease since Nineteen-Fifty. The researchers say there has been a twenty percent decrease in the amount of water in the past fifty years.
Mr. Hansen also says there is an increase in the speed at which the area is losing its cold deep water. He says the flow has decreased faster in the last five years than it did over the forty-five years before.
The current is part of a flow of water that travels thousands of kilometers. Scientists say there is much they still do not understand about this flow of water. They say it can change greatly in different areas over different periods of time. Mr. Hansen's study gathered measurements over a longer period of time than any other study of the flow through the ridge. However, he says the measurements must continue before scientists can learn what is causing the decreased flow through the ridge. He says there is not enough information to decide whether the change is linked to warming of the atmosphere caused by human activity.
This VOA Special English SCIENCE REPORT was written by Caty Weaver.