So the ocean affects climate by storing and transporting huge amounts of heat and carbon dioxide, and so if we want to understand how the climate’s going to evolve in the future we need to know what’s happening in the oceans. About 90% of the extra heat energy that’s been stored by the Earth’s system over the last 50 years is in the ocean, so when we talk about global warming we’re really talking about ocean warming in a real sense. So one of the main goals of our work in the Southern Ocean is to measure exactly that, how is the ocean changing and to learn how ocean changes might affect things like climate, sea level rise and biological productivity. The Southern Ocean’s a really important part of the ocean to study because it’s really unique in a number of ways. First of all, it’s only in the Southern Ocean that there’s a band of ocean that circles around the Antarctica that’s totally unbroken by land, it’s a continuous channel of water, and it turns out that the dynamics of the ocean currents that circulate in that channel are very different from the rest of the globe. It’s the home to the world’s largest ocean current, it carries about 150 million cubic metres of water every second from west to east south of Australia, between Australian and Antarctica, and that connection between the ocean basins that’s formed by that current transforms the whole global pattern of ocean circulation and also affects global climate, not just the climate of the Southern Ocean region.
That strong current, one of things it does is prevent heat from spreading from the relatively warm northern latitudes further south, and so it helps contribute to the icy glacial climate that Antarctica experiences today. It also has a big impact on Australian climate because it affects the weather systems that come across the continent from the south, so our weather in Australia is largely determined by what happens in the oceans around us, either the Pacific, the Indian and the Southern Ocean for the southern part of the continent. Another thing that makes the Southern Ocean very different from the rest of the ocean is that it’s one of the few places, or the only place where water that’s at depth in the ocean, three or four thousand metres below the surface in most of the ocean, rises all the way to the sea surface in the Southern Ocean.
And so it’s the only place where the atmosphere connects to the deep ocean and that has a lot to do with how much CO2 remains in the atmosphere..