This Towering Iceberg That Broke Free of Antarctica Last Year Doesn't Want to Leave
This time series of Sentinel-1 satellite radar imagery shows that Iceberg A-68 hasn't traveled far since it broke off July 12, 2017.
Credit: Adrian Luckman/Swansea University

An entire year has passed since a Delaware-size iceberg broke away, in dramatic fashion, from the Larsen C Ice Shelf in Antarctica. But it hasn't traveled far. Instead, dense sea ice in the Weddell Sea has kept the iceberg close to its former home, according to newly acquired satellite imagery.

But even though this icy giant — dubbed A-68 — is a homebody, it's still taken a beating since it calved from the ice shelf on July 12, 2017. Ocean currents have pushed the gigantic iceberg around, as have tides and winds.

Moreover, the iceberg's north end has repeatedly grounded in shallow waters near Bawden Ice Rise, and these groundings splintered off pieces of A-68 in May 2018, according to a blog post from the British Antarctic Survey's research group Project MIDAS. [In Photos: Antarctica's Larsen C Ice Shelf Through Time]

These shattered pieces aren't large enough to be considered separate icebergs, but the total area of the slivers lost in May is equal to the size of a small city, according to the MIDAS blog. Adrian Luckman, a professor of geology at Swansea University in the United Kingdom who is part of Project MIDAS, tweeted a GIF of the splintering iceberg shortly after it happened.

The combined size of these slivers may sound large, but it's nothing compared with the girth of A-68. The beast weighs more than a trillion tons and contains enough ice to cover all 50 U.S. states (including Hawaii and Alaska) with 4.6 inches (11.6 centimeters) of ice, according to Climate Central. At 2,240 square miles (5,800 square kilometers), it's the sixth largest known iceberg since record keeping began, the MIDAS blog reported.

However, none of this activity is unexpected, said the European Space Agency (ESA), which operates the Sentinel-1 satellite that's monitoring the iceberg. After A-68 broke off last year, the agency noted that "The iceberg's progress is difficult to predict. It may remain in the area for decades, but if it breaks up, parts may drift north into warmer waters."

The ESA added that "since the ice shelf is already floating, this giant iceberg does not influence sea level." However, when an iceberg breaks off, "it promotes faster discharge of grounded ice [in Antarctica], which increases sea level," a group of scientists who study changes in Antarctic ice shelves wrote on The Conversation in June.

A-68's existence has sparked a debate among scientists. A 2018 study in the journal Geophysical Research Letters showed that the remaining Antarctic Peninsula ice shelves across the region have gotten taller since 2009, according to study's researchers, who also wrote The Conversation piece.  

"Using atmospheric models backed up by field observations, we connected this height recovery to a regional cooling that persisted for several years and reduced summertime surface melting," the scientists said. "The large calving event was likely a normal mass-loss process, similar to a larger event in 1986."

In other words, "there is so far no clear indication that Larsen C is on the brink of collapse," the scientists noted.

But not everyone agrees. [Icy Images: Antarctica Will Amaze You in Incredible Aerial Views]

"To me, it's an unequivocal signature of the impact of climate change on Larsen C," Eric Rignot, a glaciologist at NASA's Jet Propulsion Laboratory, told CNN last year. "This is not a natural cycle. This is the response of the system to a warmer climate from the top and from the bottom. Nothing else can cause this."

Scientists do agree, however, that melting Antarctic ice from climate change does lead to increased sea levels, which can impact people living in coastal areas. Antarctica is losing land ice at an accelerating rate, and it could become the "largest contributor to sea-level rise by the middle of this century," the scientists wrote in The Conversation.

Project MIDAS will continue to monitor A-68. For updates, check its blog.

Original article on Live Science.