Freshening of deep Antarctic waters could throw Earth’s climate into chaos
April 19th, 2008 by Jim JustA team of Australian scientists have found that the salty, dense water that sinks near the edge of Antarctica to the bottom of the ocean about 5 km (3 miles) down is becoming fresher and more buoyant.
This Antarctic deep water helps power the great ocean conveyor belt, a system of currents spanning the Southern, Pacific, Indian and Atlantic Oceans that shifts heat around the globe. If thet freshening trend continues, eventually the water near Antarctica would be too light and buoyant to sink and that limb of the global-scale circulation would shut down.
This is one of the switches in the climate system – and scientists are trying to find out if we are about to flip that switch or not. If these currents were to slow or stop, the world’s climate would eventually be thrown into chaos.
The leading hypothesis at the moment for why it’s freshening is that the floating ice around Antarctica is melting more rapidly than in the past. Studies show winds around Antarctica are changing because of global warming and the ozone hole, causing more upwelling of relatively warm water from below and melting the ice around Antarctica.