LARSEN ICE CRACK CONTINUES TO OPEN UP...

 

The crack that looks set to spawn a giant iceberg in the Antarctic has continued to spread...

The rift in the Larsen C Ice Shelf has grown a further 10km since 1 January.

If the fissure propagates just 20km more, it will free a tabular berg one-quarter the size of Wales.

That would make it one of the biggest icebergs ever recorded, according to researchers at Swansea and Aberystwyth universities, and the British Antarctic Survey.

News of the lengthening crack in the 350m-thick floating ice shelf on the eastern side of the Antarctic Peninsula comes from the EU’s Sentinel-1 satellite system.

Comprising two spacecraft, this orbiting capability can continuously monitor Larsen C no matter what the weather is doing because its radar sensors see through cloud.

Their data indicates the fissure now extends for some 175km. But just how long it will take before the 5,000 sq km block finally breaks free is anyone’s guess, says Swansea's Prof Adrian Luckman.

"The rift tip has just entered a new area of softer ice, which will slow its progress," he told BBC News.

"Although you might expect any extension to hasten the point of calving, it actually remains impossible to predict when it will break because the fracture process is so complex.

"My feeling is that this new development suggests something will happen within weeks to months, but there is an outside chance that further growth will be slow for longer than that.

"Sometimes rift growth is triggered by ocean swell originating elsewhere, which is also hard to predict."

 Images taken in November last year illustrate the scale of the rift. Image copyright NASA

When the berg splits away, interest will centre on how the breakage will affect the remaining shelf structure.

The Larsen B Ice Shelf further to the north famously shattered following a similar large calving event in 2002.

The issue is important because floating ice shelves ordinarily act as a buttress to the glaciers flowing off the land behind them.

In the case of Larsen B, those glaciers subsequently sped up in the absence of the shelf. And it is the land ice - not the floating ice in a shelf - that adds to sea level rise.

If Larsen C were to go the same way it would continue a trend across the Antarctic Peninsula.

In recent decades, a dozen major ice shelves have disintegrated, significantly retreated or lost substantial volume - including Prince Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie, Muller, Jones Channel, and Wilkins.

How the rift appeared to Sentinel-1 at the beginning of the month. Image copyright ESA/EU/Copernicus 

Another development to watch will be the behaviour of the free floating berg, and its progress away from the Antarctic.

"Sea ice in the region circulates clockwise with the Weddell Gyre, rather than remaining in one place, and icebergs can be carried with this, sometimes out into the Southern Ocean," explained Prof Luckman.

"It all rather depends on how soon the iceberg breaks up, and how the iceberg draft compares with ocean depths.

"Ocean depths are not perfectly known in the region precisely because the near continuous ice cover makes ship operations difficult."

Many of the big tabular bergs produced in this region of the Antarctic get swept up in currents that eventually take them north towards the British overseas territory of South Georgia.

There, they can be caught in shallow waters to gradually wither away.

This ocean conveyor is the same one exploited by Ernest Shackleton to get his crew to safety when their ship, the Endurance, was crushed in thick sea-ice in the Weddell Sea in 1916.

The remnants of many such bergs end up at South Georgia. Image copyright Thinkstock 

 

The mighty A-38 berg reached South Georgia after six years of drifting.  Image copyright NASA

  • 20 January 2017

Jonathan.Amos-INTERNET@bbc.co.uk 

Twitter: @BBCAmos

source: http://www.bbc.com/

original story HERE

 

If you would like to share this blog story on Facebook with one easy click, scroll down to the very bottom of this page and look for the SHARE button along with the Facebook LIKE button under the "Sign up to Learn About & Help End Global Warming” boxed area where people enter their email address. You do not need to enter any email address to use the one click Facebook SHARE button.

Get more of The Global Warming Blog. Bookmark this page and signup for the blog’s free RSS Feed. Sign up for free Global Warming Blog by clicking here. You will automatically be emailed a regular summary of the latest global warming headlines.

To learn about more about global warming, climate change or greenhouse gases as well as the causes, consequences, solutions, definitions, facts and tipping points related to these subjects, click here.
 
To see our most current positions, opinions, comments, agreement or disagreement with this article, and/or possible criticisms related to the subjects or facts raised in the above article, click here.  Then look for those subjects in the navigation links at the top the page.

To sign a critical petition for declaring an international global warming State of Emergency, click  here!

 

Sign Up for Our Free Global Warming Blog RSS feed by clicking here. About once a week you will automatically get all the best blog stories of the week. (The blog now has thousands of articles.)

Share This Blog Post: If you would like to share this blog post, go to the original shorter version of this post and look to lower right for the large green Share button. Ask them to sign up too for the Global Warming Blog.

Click here for information on the groundbreaking and disruptive new Climageddon book. It is about the global warming emergency and what you can do to help end it!
To View Our: current positions, opinions, agreement or disagreement with this blog article or its facts, click here.

Be the first to comment

Please check your e-mail for a link to activate your account.
Sign Up For Newsletter Take Action Donate

David Pike, Editor