Since the greenhouse effect could alter the amount of Antarctic bottom water
supplied to the world's oceans, expedition researchers will also try to determine the rate at which bottom water leaves the Weddell.
They found that Antarctic Bottom Water has been disappearing at an average rate of about 8 million metric tons per second over the past few decades, equivalent to about 50 times the average flow of the Mississippi River, according to statement from the National Oceanic and Atmospheric Administration (NOAA), which helped fund the data collection.
"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," said lead author of the study Sarah Purkey, a graduate student at the University of Washington in Seattle.
We know that Antarctic Bottom Water is formed at very high latitudes in the southern oceans and spreads northward, passing through the Brazil Basin into the North Atlantic.
The schematic below shows the mean flow of Antarctic Bottom Water in the deep basin with a steady deep western boundary current.
Oceanographers have noticed that Antarctic Bottom Waters, a massive current of cold, salty and dense water that flows 2,000 meters under the ocean's surface from near the Antarctic coast toward the equator has been shrinking in recent decades.
Along with colleagues, Marinov used models to discern whether the shrinking of the Antarctic Bottom Waters could be attributed to anthropogenic climate change.