Amount of Antarctic Bottom Water decreasing for decades

Image by Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany

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Two oceanographers from NOAA and the University of Washington find that Antarctic Bottom Water has been disappearing at an average rate of about eight million metric tons per second over the past few decades, equivalent to about fifty times the average flow of the Mississippi River or about a quarter of the flow of the Gulf Stream in the Florida Straits.

"Because of its high density, Antarctic Bottom Water fills most of the deep ocean basins around the world, but we found that the amount of this water has been decreasing at a surprisingly fast rate over the last few decades," said lead author Sarah Purkey, graduate student at the School of Oceanography at the University of Washington in Seattle. "In every oceanographic survey repeated around the Southern Ocean since about the 1980s, Antarctic Bottom Water has been shrinking at a similar mean rate, giving us confidence that this surprisingly large contraction is robust."

Read the full article in the Journal of the American Meteorological Society.