4500m deep: remote observatory expands climate knowledge

Why that part of the ocean important?

Why specifically south of Tasmania?

Yeah.

Well, so, I mean, Australia has a vast marine estate, I guess, as most people would know.

And part of that marine estate comprises parts of the Southern Ocean, right? And the Southern Ocean is incredibly important because of the role that it plays in the Earth's climate.

And so we want to be in that location specifically because we know this is a region of global significance for uptake of excess or extra if you want heat that's in the atmosphere because of human activities and also for the uptake and storage, which is important.

of extra or anthropogenic CO2.

So CO2 that ends up in the ocean as a result of our human activities on land, burning of fossil fuels.

There are specific areas in the ocean where those signals are, where that CO2 is stored and kept away from the atmosphere over long timescales.

And this region in the sub-Antarctic, south of Tasmania, is one of these regions that has global importance.

So that's why we want to be there.

In addition to some practical constraints, it's being accessible from Hobart by ship, for example.

Okay, so let's go step by step on that actual process of how the ocean takes the CO2 out of the atmosphere and the service it's actually doing for us.

So what is actually happening when carbon dioxide moves from the air into the ocean? How does that work?

So gas has become dissolved in seawater.

So it's a little bit like bubbles in a carbonated drink, but different because we're dealing with seawater.

So the atmosphere and the ocean talk to each other, right? They are in contact.

And when CO2 moves from the atmosphere into seawater, it undergoes a series of chemical reactions and becomes what we refer to as a dissolved gas.

It ends up mostly in a chemical form called bicarbonate, which is very stable and long-lived in the ocean.

And so once the CO2 is dissolved in seawater, it's kind of at the mercy of the currents.

It gets moved around with the physical oceanographic circulation.

So some water will move from the surface into the deep ocean interior where it won't anymore have contact with the atmosphere for centuries or longer.

And in other areas of the ocean, some of that water is moved from the interior ocean up to the atmosphere where it could interact again and possibly some of that CO2 quit out gas, back to the fizzy drink, a bit like when the soda that you're drinking becomes flat, right? The gases are coming out of solution.

So we've done a podcast on ocean currents.

And so understanding those ocean currents, we understood from the lost ducks that the currents can take the ducks around the world in like 100 years or something.