Either their mechanism is wrong or this sporadic sampling is giving the wrong impression (I wonder if the circumpolar wave is skewing their measurements?). Satellite measures tell us unequivocally that Antarctic sea ice has been slowly increasing for many decades, so production of super-cold dense brine should also be increasing but:
AUSTRALIAN historian and lyrical Antarctic observer Tom Griffiths once likened Antarctica to a giant, breathing organism clamped to the base of the globe, a ”billowing creature rhythmically expanding and contracting” from winter to summer.
”When the surface of the sea turns to ice, it releases a dense brine that plunges to the ocean depths, and that thrust of salty water to the sea floor is the piston-stroke that drives the engine of ocean circulation, sending cold Antarctic bottom-water northwards, even infiltrating the northern hemisphere,” he wrote in his award-winning book documenting a voyage through the southern ice, Slicing the Silence.
Last summer, scientists on another voyage into the high latitudes – one coinciding with the centenary of Sir Douglas Mawson’s Australian Antarctic Expedition – continued in Mawson’s footsteps, collecting measurements and observations across a route from Hobart due south to the end of the earth, then north to Fremantle.
A particular preoccupation was reaching deep into the Southern Ocean abyss to collect and analyse samples of Antarctic bottom-water, the density of which is determined by coldness and salinity.
Preliminary analysis of the material that the team hauled back on board the icebreaker Aurora Australis over 25 arduous days – working round-the-clock shifts to collect measurements from the ocean floor at 77 sites – indicates that the character of the deep ocean is changing profoundly. The densest waters in the world are gradually disappearing and being replaced by less dense waters.
Yesterday the chief scientist of this latest expedition, Dr Steve Rintoul of CSIRO and the Antarctic Climate and Ecosystems CRC, reported his team’s findings back to a meeting of the Australian Academy of Science convened in Canberra to mark 100 years of Antarctic science.
“It’s a clear signal to us that the oceans are responding rapidly to variations in climate in polar regions. The sinking of dense water around Antarctica is part of a global pattern of ocean currents that has a strong influence on climate, so evidence that these waters are changing is important,” Rintoul says.