Iceberg bigger than the city of Toronto floats away from Antarctica

Back in November of 2013, NASA's Terra and Aqua satellites spotted a massive iceberg calving off from Antarctica's Pine Island Glacier. It's taken roughly five months to do it, but this city-sized block of ice has slowly migrated away from the continent, and is now floating out to sea.

According to NASA's Earth Observatory, the estimated size of this iceberg, named B-31, is around 660 square kilometres (33 km long by 20 km wide).

"While some mass was lost very early on in the life of B-31, it has remained pretty much the same shape since early December and is still about six times the size of Manhattan," Grant Bigg of the University of Sheffield, told NASA's Earth Observatory. "Going on measurements of Pine Island glacier before the calving — and hints of partial grounding in the history of the iceberg movement — we think it is possibly 500 meters thick."

That makes B-31 so big that it would completely encase the city of Toronto, with room to spare, and only the last 50 or so metres of the CN Tower's antenna would be left sticking out of the top to give any hint about where the city was located.

This time-lapse video shows B-31's movements over the past five months, as the sea ice in Pine Island Bay melted away during the Antarctic spring and summer, clearing the way for B-31 to be swept out to sea:

This represents an amazing opportunity for scientists to study iceberg migration. Both before and after the iceberg broke off, scientists dropped javelin-shaped GPS trackers — Aircraft Deployable Ice Observation Systems (ADIOS) — onto its surface, allowing them to gather accurate readings on its location to supplement the satellite data.

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Although there are concerns about Antarctic ice melting due to climate change, it's not clear yet whether or not the calving off of B-31 is something to be specifically concerned about.

"Iceberg calving is a very normal process," Kelly Brunt, a glaciologist at NASA’s Goddard Space Flight Center, said on the Earth Observatory page. "However, the detachment rift, or crack, that created this iceberg was well upstream of the 30-year average calving front of Pine Island Glacier (PIG), so this a region that warrants monitoring."

(Image courtesy: NASA's Earth Observatory)

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