Image: NASA Earth Observatory

A Trillion-Ton Iceberg Just Broke Off Antarctica

Now what?

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Jul 12 2017, 12:46pm

Image: NASA Earth Observatory

A trillion-ton iceberg that scientists have been closely monitoring for years has broken off of the Larsen C ice shelf in Antarctica, according to Project Midas, a UK-based research group that has been monitoring it. The iceberg, which Project Midas says is likely to be named "A68," has a volume equal to double that of Lake Erie in the Great Lakes. Its long-anticipated calving was also confirmed by the European Space Agency.

The break-off happened sometime between Monday and Wednesday of this week, when a 5,800 square km section broke off the ice shelf. It's hard to say what will happen to the iceberg, although scientists say it will probably gradually break up into fragments, with some of the ice staying in the region for decades.

Though icebergs breaking off of ice shelves is a normal, natural phenomenon, the sheer size of this one has attracted worldwide attention. If your gut reaction is to blame climate change, you're not alone. But the fact is we still have very little understanding of Antarctica, because it's so remote—to study it, scientists largely rely on satellites—and the question of whether or not climate change is a factor here and to what extent is a topic of intense debate for researchers. Even so, this event could potentially worsen some of the effects of climate change.

Floating ice shelves buttress glaciers on land, and their break-up can cause a rapid flow of glacial ice into the sea, potentially triggering sea level rise. There has been some concern that this large break-off could destabilize the Larsen C ice shelf—one of multiple floating sheets of ice attached to Antarctica. When two nearby ice shelves, Larsen A and Larsen B, collapsed in 1995 and 2002, glaciers flowed with increasing speed into the ocean.

Because the iceberg was already floating before breaking away, it hasn't had an immediate impact on sea levels, Project Midas notes.

It's impossible to say for now how this will play out on the Larsen C ice shelf. What's left of the ice shelf is expected to regrow, although it could potentially be less stable as a result of the calving, Project Midas notes. This represents the first time scientists have been able to monitor a calving like this, via satellite, in near real time, so researchers are saying it's a rare opportunity to study these processes as they occur and get a better understanding.

"To be clear, the remaining floating glacial ice in the shelf does not appear to be showing signs of further rifting, but it is also the middle of the austral (southern hemisphere) winter, so we'll need to keep watch in subsequent warmer weather, possibly for many years," Christopher A. Shuman, a research scientist within the Cryospheric Sciences Laboratory at NASA Goddard Space Flight Center, told Motherboard in an email.

Larsen C is one of the largest ice shelves on the continent, and this calving reduced its area by more than 12 percent, according to Project Midas, which notes that the event has left "the landscape of the Antarctic Peninsula changed forever."

Larsen C ice shelf crack on March 8, 2017. Image: O.V.E.R.V.I.E.W./Flickr

Mark Drinkwater, the head of the Mission Science Division at ESA-ESTEC, the research arm of the European Space Agency, said ice calvings in general shouldn't be cause for concern.

"These events have been a regularity over the last 40 years, but now we have tools that can watch this stuff happening from one day to the next," Drinkwater said in a phone call. "It's focused attention to how Antarctica is changing due to climate, although there's no indication this [calving] has anything to do with climate."

Read More: These Stunning Photos Document a Changing Climate in Antarctica

Drinkwater clarified that there's no question that climate change, which has caused warmer ocean temperatures, has had an impact on some ice calving events, but that this particular event just isn't conclusive. In the wider glacial science community, multiple researchers told me there is an ongoing debate about whether or not climate change played a role in this ice calving, and to what extent, as well as what the larger implications of this event may be.

Swansea University glaciologist Martin O'Leary noted in the Project Midas release that, while his team isn't aware of a link to human-induced climate change, it leaves Larsen C in a vulnerable position. "This is the furthest back that the ice front has been in recorded history," he said. "We're going to be watching very carefully for signs that the rest of the shelf is becoming unstable."

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