Tuesday January 24, 2017 Q&A

What will happen after the breakup of the Larsen C ice shelf in Antarctica?

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1 A significant rise in global sea levels

2 A massive shockwave that will kill whales

3 A tsunami on Cape Horn

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Answer: A significant rise in global sea level A massive slab of ice – more than one and a half times the area of the Canton of Vaud – is on the brink of falling off the western side of the Antarctic ice shelf. This 5000 km2 slab of ice, 350 m thick, first started to detach from the great Larsen C ice shelf in 2010. The fissure has widened regularly over the years, until December 2016 when the process accelerated quickly, progressing 20 km in only 2 weeks. Today, only 20 km remain until the slab of ice completely breaks off (“calves”) from the shelf and floats off into the ocean. The event is inevitable in the coming weeks or months – we are just at the beginning of the southern summer. These huge ice shelves have a critical function: they act as a barrier to the vast glaciers covering the continent. When shelves like this break up, as was observed in the rupture of Larsen B (3250 km2) in 2002, the continental glaciers can accelerate their slide into the sea. Larsen C covers an area of 50,000 km2. Scientists think that when this ice slab calves, it will lead to a weakening of the entire shelf — exactly what happened to Larsen B. After that rupture, Larsen B broke apart in only three days. This opens up a pathway for the glaciers to rapidly “flow” into the ocean. According to estimates, this could result in a rapid elevation of global sea levels by 10 cm. The scientific vessel Akademik Treshnikov has just left Tasmania for the second stage in its expedition around the Atlantic, and it will encounter Larsen C at the end of February. Will the scientists on board see an ice slab or an iceberg? We’ll find out in several weeks. http://www.projectmidas.org/blog/larsen-c-ice-shelf-poised-to-calve/