Torrents of Antarctic meltwater are slowing the currents that drive our vital ocean ‘overturning’ – and threaten its collapse

[Eric]

Torrents of Antarctic meltwater are slowing the currents that drive our vital ocean 'overturning' – and threaten its collapse

In a plot reminiscent of the 2004 movie The Day After Tomorrow?, Australian scientists are warning that the Southern Ocean’s deep “overturning” circulation is slowing and headed for collapse.

theconversation.com

Off the coast of Antarctica, trillions of tonnes of cold salty water sink to great depths. As the water sinks, it drives the deepest flows of the “overturning” circulation – a network of strong currents spanning the world’s oceans. The overturning circulation carries heat, carbon, oxygen and nutrients around the globe, and fundamentally influences climate, sea level and the productivity of marine ecosystems.

But there are worrying signs these currents are slowing down. They may even collapse. If this happens, it would deprive the deep ocean of oxygen, limit the return of nutrients back to the sea surface, and potentially cause further melt back of ice as water near the ice shelves warms in response. There would be major global ramifications for ocean ecosystems, climate, and sea-level rise.