Robot boats set sail around the Southern Ocean on 9-month journey

We want to know how much carbon dioxide is making its way from the atmosphere into the ocean.

And because the Southern Ocean is so vast, and because, as I said, defining it as 30 degrees south, if you think about the map on your wall, most of the land masses are in the Northern Hemisphere, right? So in terms of the whole global carbon budget, the Southern Ocean is just more and more important because there's so little land around.

So I guess taking a little step back, We're trying to understand where the CO2 from our human emissions ends up.

So we know about a third of it stays in the atmosphere.

That's how come the atmospheric concentration just keeps going up with time as we do more burning of fossil fuels.

We know about a third of it gets taken up by what we call the terrestrial biosphere.

So that's plants on land.

So growing trees and soils and the remaining third goes into the ocean.

Of that third, the Southern Ocean is doing the heavy lifting because it's just so much of the planet in the Southern Hemisphere.

But we have really high uncertainty about how much actually ends up there because we have so few observations to use to generate those numbers.

So when it does end up there, are you also able to see where it goes and how deep and all those sort of things and see what happens to it eventually?

Yes, we are.

We know that the Southern Ocean in particular is important because it's a place where you have waters that are in contact with the current atmosphere that then get sequestered or shoved down deep into the ocean interior and they carry that signal of CO2 with them.

Thinking back way to the pre-industrial, before humans were emitting lots of CO2 into the atmosphere, the Southern Ocean was actually a source of CO2 through the atmosphere.

There were times when the ocean was releasing CO2 to the atmosphere.

That was part of the balance that the planet was in several hundred years ago.

We're currently in a different state.

We know that we're increasing the concentration in the atmosphere and the ocean is largely keeping up with that.

It's taking up about a third of our emissions every year.

But we don't know exactly where.

We don't know exactly how.

And I guess I mean by that the balance of the physics and biology that needs to be in place to move that CO2 from the surface into the ocean interior and stuff it away where we can rely on it staying for hundreds of thousands of years.

So

we're

interested in having a better handle on how much CO2 goes in and where it ends up and how long it might stay there for.