viernes, 24 de febrero de 2017

Giant Antarctic iceberg set to break away

An iceberg expected to be one of the 10 largest ever recorded is ready to break away from Antarctica, scientists say. A long-running rift in the Larsen C ice shelf grew suddenly in December and now just 20km of ice is keeping the 5,000 sq km piece from floating away.

Self-study activity:
Watch the video and answer the questions below.

1 How long is the Larsen C ice shell?
2 What has surprised the team of British researchers in Antarctica?
3 How big will the new iceberg be if it breaks off?
4 How long did it take Larsen B to disintegrate when icebergs broke off in 2002?
5 What are the consequences for the environment when ice shelf loses so much ice?
Stretching for around 100 miles in length, the hundred-yard wide rift in the Larsen C ice shell has grown rapidly in recent weeks. Just 12 miles of frozen material is keeping this enormous iceberg from drifting away into the sea. Collapsing ice shelves are not uncommon in Antarctica. As these picture show, these fragmentations can dramatically affect the life, creating icebergs of all shapes and sizes.
A team of British researchers have been travelling down to Antarctica to monitor the growing crack in the in the Larsen sea ice shelf for several years, but they have been surprised by the dramatic expansion in the rift that’s taken place in just two weeks in December.
What we’ve found is that the rift that’s been in there in this ice shelf for a number of years has broken through another 18 kilometres and is now at risk of giving birth to an iceberg about a quarter of the size of Wales. And the significance of that is that it’s a very large iceberg that will go out into the open ocean, but also that the remaining ice shelf, we believe, will be less stable than before the rift was there.
When large icebergs break off the edge of an ice shelf, like the Larsen B in 2002, it can have a dramatic effect on the stability of the entire structure, and Larsen B most of the remaining shelf disintegrated in less than a month.
Experts at the British Arctic Survey are worried that any new iceberg formation could have long-term consequences.
When the ice shelf loses this ice, it may then start to collapse and if that were to occur then the glasses that feed the ice shelf could flow faster and contribute more to sea levels rise over the next few decades.
When it sheers away, the new iceberg will be one of the biggest ever recorded, about 50 times the size of Manhattan Island. But despite concerns over the impacts on global warming, researchers say they have no evidence that climate change is playing any significant role in the new icebergs formation.
Matt McGrath, BBC News.

1 around 100 miles
2 how quickly the crack is growing
3 a quarter the size of Wales
4 less than a month
5 it contributes more to sea levels rise