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OUT OF THIS WORLD | Earth, Space and Everything In-Between - a daily journey through weather, space and science with meteorologist/science writer Scott Sutherland

Iceberg 5x bigger than Manhattan broke off Antarctic glacier


Scott Sutherland
Meteorologist/Science Writer

Thursday, November 1, 2018, 9:18 PM - The fastest shrinking glacier in the world just lost another massive piece this week, as an iceberg roughly five times bigger than Manhattan broke off and floated away.

Scientists have been closely watching the Pine Island Glacier.

Not only is this glacier, which is located along the coast of West Antarctica, shrinking faster than any other glacier known, as a result, it is also contributing more to sea level rise than any other glacier in the world.

This week, yet another massive chunk was spotted breaking free from the glacier's leading edge. Measured at around 300 square kilometres in area, it is roughly five times the size of the island of Manhattan.

Stef Lhermitte, a remote sensing scientist with the Delft University of Technology, in the Netherlands, posted images of this new iceberg, dubbed B-46, as it calved off at the end of October.



This sequence of images, taken by the ESA's Sentinel 1 satellite at the end of September and throughout the month of October, shows the rapid spreading of a large crack across the glacier, and then the new iceberg peeling away over just the last few days in October. Since the 300 sq km iceberg broke off, it has since split into several pieces, the largest - which Lhermitte estimates at around 226 sq km - is now named B-46.

According to further posts by Lhermitte, while the leading edge of the glacier went through many small retreats and advances as scientists monitored it between 1972 and 2000, afterwards it began a series of much larger changes, with a large calving event every six years or so (2001, 2007 and 2013), and then three large calving events in just the past five years (2015, 2017 and 2018). The largest of these, according to the UK's Project iSTAR, was an iceberg 720 square kilometres in size, which calved in 2013.




This increased rate of calving is of great concern to scientists studying Antarctica, especially in the context of studying the response of West Antarctica to global warming and climate change.

The Pine Island Glacier is not only losing ice from its leading edge during these calving events, but according to Project iSTAR, the 2 km thick glacier is also thinning by around 1 metre per year, and its grounding line - the point where the glacier starts to float on water - is retreating inland by 1 kilometre each year.

All of these factors point to the increasing instability of this glacier, and from what Sentinel 1's cameras are showing us, we apparently don't have too much longer to wait until we see the next calving event.



This activity we are seeing with the Pine Island Glacier, and with the Larsen-C ice shelves along the Antarctic Peninsula, are highlighting just how much of an impact Antarctica is seeing from global warming, where warm ocean waters appear to be having the largest effect, whittling away at the stability of these glaciers and ice shelves from underneath.

Sources: Stef Lhermitte | Project iSTAR

RELATED: BIZARRE, PERFECTLY RECTANGULAR ICEBERG ACTUALLY HAS REALLY SIMPLE EXPLANATION



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