![]() ![]() We still don’t know whether this particular area is going to “regrow” or whether it will start to disintegrate. 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. It’s 12 percent or so of the entire Larsen ice shelf. We’re not talking about a little iceberg that just popped off and bobbed away. One of the things that’s significant about this current event is, it’s a huge chunk of ice. Photo courtesy of NASA Sure, it’s not imminent, but it could potentially happen, right? Collapsing ice shelves allow inland glaciers to flow more easily. Antarctica holds a huge amount of frozen fresh water. Portions of Larsen A and B ice shelves have previously collapsed. The July 2017 iceberg broke off from the Larsen C ice shelf. Nobody is saying right now that that’s imminent. But that’s if the entire ice shelf and the glaciers above it were to disintegrate. 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. 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. And that increased flow would contribute to sea-level rise? And from the previous collapse of the Larsen A and the Larsen B ice shelves, we’ve been able to see firsthand-and directly measure-how quickly the upstream glaciers have accelerated. And the Antarctic continent holds a huge amount of equivalent sea-level rise in the form of frozen fresh water, so when these ice shelves start to disintegrate, and especially if they disintegrate beyond kind of a point of no return, then those glaciers can flow more easily. The reason ice shelves are significant, though, is because they form, essentially, a cork that helps stem the outward flow of ice from the inland areas. 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. That’s the definition of an ice shelf: it’s floating on the ocean. So why does it matter if a piece of Antarctica breaks off? Will the iceberg contribute to sea-level rise? Wouldn’t that be cool? It would be pretty awesome. So it’s not going to float up to North America. But when I say “it,” I mean a piece of it, not the whole shebang. Some estimates say it could reach the Falkland Islands. 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. BU Research: What happens to the iceberg now? Is it going to float up to Boston? The interview has been condensed and edited for clarity. “It’s not hyperbole to say that some maps of Antarctica will need to be re-drawn,” says Sean Mackay, a glaciologist and member of BU’s Antarctic Research Group, above. “Sometimes it takes the giant events to get people’s attention,” he says. He spoke to BU Research about what the iceberg calving could mean for the future, and what role it might play in rising sea levels. Sean Mackay, a postdoctoral research associate at Boston University and a member of BU’s Antarctic Research Group, has an intimate relationship with Antarctica and its ice, having travelled to the continent six times over the past nine years to collect information on ancient climate change from buried glaciers and other sources of old ice. The event seemed to many an awesome-and terrifying-warning of climate change. ![]() This wasn’t the first time that a chunk of the Larsen shelf had severed, and it probably wasn’t the biggest iceberg ever, but the massive break, and dramatic photos of the 120-mile-long crack that formed it, captured the public’s imagination and made headlines worldwide. In July 2017, an iceberg the size of Delaware broke off Antarctica’s Larsen C ice shelf and floated into the sea. ![]()
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