An iceberg’s uncertain future
Scientists have been waiting for months for the piece to fall
One of the largest icebergs ever recorded breaks off from an ice shelf in Antarctica.
One of the largest icebergs ever recorded broke off from an ice shelf in Antarctica, British scientists announced Wednesday.
The 1-trillion-ton iceberg, with twice of the volume of Lake Erie, broke off from the Larsen C ice shelf between Monday and Wednesday, according to Project MIDAS, which has been monitoring the shelf. At 2,200 square miles, the chunk of floating ice is nearly the size of Delaware.
The iceberg is likely to be named A68.
Over the past several months, an ever-lengthening and widening crack in the ice shelf captivated the world. Now, the 120-mile crack first spotted in 2011 finally made its way back to the sea, “calving ” off the massive berg.
“The iceberg is one of the largest recorded and its future progress is difficult to predict,” said Adrian Luckman, a professor of Swansea University and the lead investigator of Project MIDAS. “It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.”
Previously, he said the iceberg breaking off “will fundamentally change the landscape of the Antarctic Peninsula.” The calving reduced the size of the ice shelf by some 12%.
“We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few (miles) of ice,” Luckman said. “We will continue to monitor both the impact of this calving event on the Larsen C ice shelf, and the fate of this huge iceberg.”
Unfortunately, there are no public websites allowing a live view of the iceberg or ice shelf. The development of the rift over the past year was monitored using data from the European Space Agency Sentinel-1 satellites, a radar-imaging system capable of acquiring images regardless of cloud cover, and throughout the current winter period of polar darkness.
“It’s the Antarctic winter now, and lack of sunlight means that no optical satellite data is being collected,” Luckman said in June.
Scientists obtain images from orbiting European satellites using microwave energy. But the images themselves reveal nothing, and it is only by special processing of the data that scientists can track the iceberg, Luckman said.
As for how long the iceberg will stick around, it depends on how quickly it moves to a warmer climate, and how quickly it breaks into smaller pieces.
The iceberg — or icebergs if it breaks up ever further — may remain in the region, where the ocean is quite cold, sticking around for years or even decades. Or it could move with ocean currents and winds in a northward direction, where it will be eroded more quickly.
A similar event happened 15 years ago with the dramatic breakup of part of the nearby Larsen B ice shelf.
Ice shelves are permanent floating sheets of ice connected to a land mass, according to the National Snow and Ice Data Center. Since the ice is already floating, the newly created iceberg won’t contribute to rising sea levels.
Project MIDAS said there is no evidence to directly link the calving of the iceberg to climate change. However, it is widely accepted that warming ocean and atmospheric temperatures have been a factor in earlier disintegrations of ice shelves elsewhere on the Antarctic Peninsula, most notably Larsen A in 1995 and Larsen B in 2002.
Global warming has pushed temperatures up to 5 degrees higher in the region since the 1950s and could increase up to 7 degrees more by the end of the century, putting more stress on the ice, according to Climate Central.
Regardless of whether climate change is a factor, calving is a natural part of the cycle of ice shelves. Ice flows gradually into the shelf, the shelf expands until stresses become too much, and then icebergs are formed.
Scientists think there is a possibility the remaining shelf is now too fragile to grow back to its former size.