World Oceans Day 2019
Southern Ocean - ice and awe
Dr Dirk Welsford (Program Leader, Antarctic Conservation and Management, Australian Antarctic Division)
The Southern Ocean is awesome for lots of different reasons. I mean it’s awesome to look at. Some of the biggest waves in the world come from the Southern Ocean. Waves over 10 metres high. It joins all of the world’s oceans. So, it joins the Pacific, the Indian and the Atlantic Oceans. It’s down there at the bottom of the world.
But it’s full of amazing things as well. That’s where the largest animals in the world live. So, the Antarctic blue whale lives in the Southern Ocean. It’s where a lot of the penguins and seals and things that we think about as being Antarctic, often live near or in the Southern Ocean. The other amazing thing is that one of the world’s most abundant organisms, the Antarctic krill lives in the Southern Ocean and it’s a key part of how that whole system works. It’s food for nearly everything that lives down there. It’s superabundant so there’s lots of things that can grow, happy and fat, eating krill.
And one of the amazing things about the Southern Ocean is that food web is very efficient. It’s quite short. So, you can go from sunlight to microbes, the krill eat the microbes and then you’ve got whales eating those krill. So, very efficient transfer of energy. And you can basically go from sunlight to the world’s largest organism in a very short space.
The whole process of freezing and thawing every year so the sea ice that grows and then melts every year, drives the world’s circulation as well. So, as that ice forms, it sheds the salt out of the saltwater; that salt sinks and that whole process then drives the entire circulation of the world’s oceans.
The Southern Ocean is critical to the world’s climate. So, all of our weather in Australia comes from the Southern Ocean. If you look at the weather map each day, when they do the forecast, you can actually see that these frontal systems are coming across the Southern part of Australia. They all are generated by Antarctica and then are transported across the Southern Ocean to us.