What Antarctica’s Massive Iceberg Could Mean for the Future

Boston University Antarctica researcher Sean Mackay explains the implications of last week’s events.

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Scientists have been monitoring the accelerating crack in Antarctic ice for more than a year. Earlier this week, the crack caused a massive iceberg to break from the Larsen C ice shelf. Photo by John Sonntag/NASA

BU Research: What happens to the iceberg now? Is it going to float up to Boston?

Mackay: We don’t really know for sure, but Antarctica has this huge circumpolar sea current, and if the iceberg can reach that current, it will most likely break up into smaller chunks and start flowing north and east. Some estimates say it could reach the Falkland Islands. But when I say “it,” I mean a piece of it, not the whole shebang. So it’s not going to float up to North America.

That’s too bad.

I know. Wouldn’t that be cool? It would be pretty awesome.

So why does it matter if a piece of Antarctica breaks off? Will the iceberg contribute to sea-level rise?

Ice shelves are floating. That’s the definition of an ice shelf: it’s floating on the ocean. So the ice shelf itself, whether or not it’s attached to the Antarctic Peninsula, won’t contribute to any kind of sea-level rise.

Wow. And that increased flow would contribute to sea-level rise?

Yes. Once the grounded ice that’s above sea level starts flowing and accelerating and getting into the global inventory of seawater, then it absolutely contributes to sea-level rise. To put it in perspective, if all of the glaciers situated above the entire Larsen ice shelf were to flow down into the ocean, we’re looking at maybe 8 to 10 cm of sea-level rise. But that’s if the entire ice shelf and the glaciers above it were to disintegrate. Nobody is saying right now that that’s imminent.

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Sure, it’s not imminent, but it could potentially happen, right?

Yes, for sure. One of the things that’s significant about this current event is, it’s a huge chunk of ice. We’re not talking about a little iceberg that just popped off and bobbed away. It’s 12 percent or so of the entire Larsen ice shelf. And the question is whether or not this may destabilize the entire system, so suddenly the entire ice shelf becomes more dynamic and may undergo a rapid disintegration. But then again, it may not. We still don’t know whether this particular area is going to “regrow” or whether it will start to disintegrate.

I know that scientists are reluctant to tie specific events to climate change. Do you feel confident saying that this iceberg is a result of climate change?

In the context of all the other things going on in the region, my gut feeling is that climate change certainly contributed to it. However, as you said, it is not possible to draw a direct connection between climate change and this exact specific event. Ice shelves naturally shed ice from time to time. But yes, my gut tells me that something is up.

You have a personal relationship with Antarctica, and also a stake in it as a scientist. How does this event make you feel?

It’s almost theatrical, right? As a human, I see an event like this and it’s awe-inspiring and beautiful and fascinating to watch. It’s a huge symbol — the breakup of ice — which is connected to all kinds of other social and global issues that we’re facing these days. But then I have to temper that by recognizing that things happen on time scales which are not always easy to grasp as human beings, and that this could be a once-every-so-many-thousand-year event that occurs, and then the ice shelf replenishes itself. My gut feeling is that it’s not, is that it is a harbinger of more changes to come. But it’s just simply too difficult for me to make a call right now.

And what about the penguins. Are there penguins on the chunk now, floating away? Separated, parent from child?

As far as I know, the penguins didn’t particularly like this ice shelf anyway. Penguins tend to like places where they can get in and out of water pretty easily, and there’s no known major penguin rookery on the ice shelf. So the penguins aren’t floating away. There are other threats on penguins, don’t get me wrong, but not this one.

Cutting-edge research and commentary out of Boston University, home to Nobel laureates, Pulitzer winners and Guggenheim Scholars. Find an expert: bu.edu/experts

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