On July 12, a giant iceberg was born as a chunk some 6,000 km2 (2,300 mi2) broke away from the Larsen C ice shelf in Antarctica. The breakup was the result of an 18-month suspense story, as scientists watched the crack extend across the ice. But with the berg now adrift and satellites continuing to monitor the site, it seems the saga isn't over yet: the remaining cracks are spreading towards a feature that's integral to the stability of the rest of the ice shelf.
Several satellites have been watching the site for months to study the effects of climate change on the region, and now that there's a huge new iceberg floating around, they're tracking its movements to keep any shipping lane chaos to a minimum. So far, the berg, which has been officially named A68, has drifted about 5 km (3.1 mi) away from the remaining shelf.
Larsen C lost about 10 percent of its area after the calving, with the event also creating at least 11 smaller icebergs up to 13 km (8 mi) long, splintering off from both A68 and the mainland. But that number could be set to rise as a network of cracks creeps across the ice towards a key part of the landscape.
"The satellite images reveal a lot of continuing action on Larsen C Ice Shelf," says Anna Hogg, a researcher at the University of Leeds. "We can see that the remaining cracks continue to grow towards a feature called Bawden Ice Rise, which provides important structural support for the remaining ice shelf. If an ice shelf loses contact with the ice rise, either through sustained thinning or a large iceberg calving event, it can prompt a significant acceleration in ice speed, and possibly further destabilization. It looks like the Larsen C story might not be over yet."
The researchers are careful not to claim that the breakaway was a direct result of climate change, since the rate of collapse isn't entirely unprecedented. This kind of thing happens naturally during the life cycle of ice shelves, but it may have been accelerated by changing environmental conditions. Satellites will continue to monitor the area to learn about the processes at work.
"Although floating ice shelves have only a modest impact on of sea-level rise, ice from Antarctica's interior can discharge into the ocean when they collapse," says Hilmar Gudmundsson, a researcher from the British Antarctic Survey. "Consequently we will see increase in the ice-sheet contribution to global sea-level rise. With this large calving event, and the availability of satellite technology, we have a fantastic opportunity to watch this natural experiment unfolding before our eyes. We can expect to learn a lot about how ice shelves break up and how the loss of a section of an ice shelf affects the flow of the remaining parts."
A paper on the calving event was published in the journal Nature Climate Change, and the speed of the breakup can be seen in the video below.
Source: University of Leeds