Giant Iceberg Spotted By NASA Satellite In Antarctica Drifting Out To Sea [VIDEO]
An antarctic iceberg six times the size of Manhattan is drifting toward the Southern Ocean, soon to be swept into its brisk currents, NASA announced this week. The space agency's Earth-trained satellites have been tracking the iceberg since it broke off, or "calved," from the Pine Island Glacier in September 2013.
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"Iceberg calving is a very normal process," said Kelly Brunt, a glaciologist at NASA's Goddard Space Flight Center, in the NASA statement. "However, the detachment rift, or crack, that created this iceberg was well upstream of the 30-year average calving front of Pine Island Glacier, so this a region that warrants monitoring."
This portion of Western Antarctica has already been the subject of intense scrutiny by ocean and climate scientists. In 1981, Pine Island Glacier and the other ice shelves around the Amundsen Sea were dubbed "the weak underbelly" of the antarctic ice sheet. There have been several international expeditions to the area to drill ice cores, but satellite images have offered some of the strongest evidence that the glaciers have been melting at an accelerating rate since the 1970s.
More urgently, the drifting of this new ice island, known as B31, could become an obstacle for cargo ships traveling off the southern tip of Chile. With the onset of winter in the southern hemisphere, and its six months of polar darkness, NASA worries that it will be more difficult to track B31. Already, its view has been obscured at times by cloud cover.
But there's more than one way to track an iceberg. The British Antarctic Survey, in January 2013, flew over B31 and speared it with 37 javeline-length tracking darts called ADIOS, Aircraft Deployable Ice Observation Systems. "B31 has been well-tracked," said David Jones of the Survey. "We have been able to study its dynamics from early on in its lifecycle."
The calving of icebergs is not an indication of climate change. It's been happening for thousands of years — long before the Industrial Revolution tipped off an era of increased greenhouse gas emissions. The antarctic ice sheet is covered with ice, which is replenished by snowfall, which then spreads outward toward the ice shelves, or glaciers, on the fringes. When the glaciers interact with the warmer ocean water, the tips break off as icebergs. What worries climate scientists is the question of whether the balance is off: Is ice breaking off faster than snowfall can replace it? A shrinking ice sheet would cause worldwide coastal flooding.
As the iceberg travels out of the Amundsen Sea, scientists will continue to monitor it for melting and any noticeable contribution to sea-level rise. When it broke off it was eight times the size of Manhattan, about 252 square miles, and one-third of a mile thick. "While some mass was lost very early on in the life of B31, it has remained pretty much the same shape since early December and is still about six times the size of Manhattan," says Grant Bigg, of the University of Sheffield, in the NASA release.
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