Latest Southern Ocean research shows continuing deep ocean change
Latest Southern Ocean research shows continuing deep ocean change
Comparing detailed measurements taken during the Australian Antarctic program's 2012 Southern Ocean marine science voyage to historical data dating back to 1970, scientists estimate there has been as much as a 60 per cent reduction in the volume of Antarctic Bottom Water, the cold dense water that drives global ocean currents.
In an intensive and arduous 25-day observing program, temperature and salinity samples were collected at 77 sites between Antarctica and Fremantle. Such ship transects provide the only means to detect changes in the deep ocean.
The new measurements, which have not yet been published, suggest the densest waters in the world ocean are gradually disappearing and being replaced by less dense waters.
"The amount of dense Antarctic Bottom Water has contracted each time we've measured it since the 1970s," said Dr Steve Rintoul, of CSIRO and the Antarctic Climate and Ecosystems CRC. "There is now only about 40 per cent as much dense water present as observed in 1970."
