A massive iceberg breaks free from Antarctica

Dave Mosher is a science reporter who has written for Scientific American, popular mechanics, National Geographic News and Discovery.com. Throughout his career, he has watched humans and robots launch into space, toured a cutting-edge nuclear reactor and flown over the north pole to catch a total solar eclipse. He joins Hari Sreenivasan to discuss the massive iceberg that broke free in Antarctica.

TRANSCRIPT

Dave Mosher is a science reporter who has written for Scientific American, popular mechanics, National Geographic news and Discovery.com.

Throughout his career he has watched humans and robots launch into space, toured a cutting-edge nuclear reactor and flown over the north pole to catch a total solar eclipse.

He joins me now to talk about the massive iceberg that broke free in Antarctica.

Give us a sense of the scale.

The scale is really hard to fathom as a human being because we just live in our own space here.

But imagine walking across Delaware, that's how, that's the surface area, volume wise it could fill up Lake Erie twice and then some.

And it's starting to break into bigger chunks and those trunks are even then still sort of unimaginable in size like you cannot really fathom how big this thing is.

It's enormous.

Suffice it to say.

And pieces of it have been breaking off for a while, been studying it for quite some time?

Yeah.

So the pieces started to break off almost immediately after it began calving, which is around July 10th, July 12th, that's when the satellite images showed us.

Yes, it had indeed broken free from this ice shelf and was now going into the Whitall sea and starting to move north.

But it's kind of stuck there right now.

But even then it's sort of banging and sloshing around and there are some meltwater on the surface that's helping cut and break the iceberg apart further.

So this is going to happen and keep happening and scientists will keep naming these chunks after the main one.

The main iceberg by the way is called iceberg A68.

So it'll be, A68A, A68B, A68B and so on and so forth.

Well I mean there's Larsen has had the ice shelf A and Ice Shelf B, those broke off.

I mean unfortunately this is not slowing down.

Yeah, so this is the main concern about about Larson C.

Most scientists are pretty confident that Larsen C is intact.

It was the fourth largest ice shelf in Antarctica and now the fifth since this iceberg capped off.

But the problem is are there more fractures they're going to happen that are going to sort of weaken the stability of that ice shelf and is it going to shed into the sea much like larcen A and Larsen B did at the turn of the 2000s.

So that is an act of concern, it's not totally worrisome at this point, but there is a new fracture, which I just learned about that is heading toward a point of stability and this ice ridge kind of keeps a lot of the ice shelves cemented together.

So if the crack reaches there then we could see the rest of the ice shelf go out in a matter of months.

What causes these cracks in the first place?

Most of the time as far as interviews, I've had it's meltwater on the surface.

That melt water is dense, denser than ice and it acts almost like a knife.

It's sort of like pushes its way and pushes apart these ice shelves.

So if you have a warming globe and on average Antarctic temperatures are much higher than the global average that we're seeing, rising temperatures you're going to have a lot of meltwater and that melt water is gonna start cutting through your ice shelf and it's going to start leading to these cracks.

So what's going to happen to this massive iceberg that just broke off.

It's going to melt.

I mean the question is how long will it take to melt: will it take a year, two years, four years, five years.

We don't know, but it's going to start moving north into the southern ocean.

And there are some experts who think it could go all the way to the Falkland Islands, the South Georgia islands, but along the way it's going to start breaking up in little tiny pieces and eventually there will be no main iceberg as we know it.

But just all of its little children melting as smaller pieces.

So is this the type of an iceberg that will impact our global sea level because it's been sitting on top or as a huge chunk of it already been underwater already and it's just now going to take a different form?

It's already sitting in the water.

So it's already displaced the water, sort of like an ice cube in your in your cocktail or your soda, whatever you prefer.

That ice cubes already displaced the liquid.

The problem that climate scientists see is all the ice behind it.

This is about 10 percent of the ice shelf.

So 90 percent of it remains, if that goes in the ocean then we will see a sea level rise maybe a centimeter, maybe two, maybe more than that.

Not totally certain, but that is, that is the concern is what all the ice behind this ice that's part of the glacier that could suddenly go into the ocean.

Dave Mosher, Thanks for joining us.

My pleasure.

Thanks for having me.