While NASA said many scientists were sceptical, it quoted Dr Robert Gagosian, director of the private Woods Hole Oceanographic Institution, Massachusetts, as saying such a change in ocean currents could happen within 20 years.
Yesterday Dr Matear explained that if global warming continued melting Arctic ice and increasing evaporation, boosting rainfall in the North Atlantic, 'the North Atlantic could be flooded with fresh water. The flood of fresh water reduces the density of the surface and prevents the water from sinking deep into ocean,' he said, adding that the vertical sinking of sea water helped drive ocean circulation.
Officially called the thermo-haline circulation, the pattern is sometimes dubbed the Great Conveyer Belt.
Dr Matear said the decline in oxygen levels in deep water of the Southern Ocean was exactly what computer modelling suggested would be seen if global warming slowed this circulation, reducing the cold water flowing south of Australia. 'Cold water is high in oxygen,' he said.
Dr Matear said although it was too early to say what impact a shutdown of ocean currents would have on Australian temperatures, he agreed Europe could be sent into a severe chill.
'A decline of five degrees by end of this century . . . that wouldn't be unrealistic.'
Dr Matear said a decline in oxygen levels would be particularly serious for sea life in the tropics, where the warmer water is already oxygen-poor.
I'm not sure who the Herald gets to subedit this stuff but 'Ocean Conveyor' is a much more common term for the thermohaline circualtion than 'Great Conveyor Belt'. It's bad news because the abrupt climate change model predicted certain behaviours in Antarctic waters, behaviours that have now been detected. Abrupt climate change within 20 years is a terrifying prospect.