Friday, June 02, 2017

200 Kms Down, 13 Kms to Go.

In Canada we're used to icebergs calved off Arctic ice sheets, especially the Greenland Ice Sheet. They're seen migrating past Newfoundland every year and have a certain reputation for sinking large ships.

There's a new iceberg in the making, one that could dwarf anything we've seen in the northern hemisphere. It's part of the Antarctic Larsen B ice shelf and it's roughly 5,000 sq km in size. A crack about 200 km long has developed but that crack has now headed toward the sea just 13 km away. Scientists describe that giant iceberg as "hanging on by a thread."

Here's what that "crack" looks like from the air.

“The rift is nearly 200km long now, and it has turned towards the ice front, suggesting that it has only got that last piece to go – and that last section is only 13km,” said Professor Adrian Luckman, a scientist at Swansea University and leader of the UK’s Midas project – an endeavour that has been monitoring the situation at the Larsen C ice shelf.

“Like any fracture in something, the longer the fracture becomes the more pressure there is on the remaining part of it. So it is really only hanging by a thread here,” he told the Guardian.

While the iceberg will not be the biggest ever recorded – the title is held by Iceberg B-15, a mass that broke off the Ross Ice Shelf in the year 2000 and had an area the size of Jamaica – it is expected to be among the top 10.

The significance of this is not immediate. What matters is that this shows that the Antarctic ice sheet may have reached a tipping point, a point of no return, that will gradually (we hope) trigger massive sea level rise.  Closer to home, scientists concluded some time ago that the Greenland ice sheet may have passed its tipping point 20 years ago.


Anonymous said...

That gradual sea level rise may not be so gradual:

[Ohio State glaciologist John] Mercer argued that this whole system [Larsen ice shelves] was more unstable than even Weertman had realized. "I contend that a major disaster – a rapid [16-foot] rise in sea level, caused by the deglaciation of West Antarctica – may be imminent," he wrote, predicting it would lead to the "submergence of low-lying areas such as much of Florida and the Netherlands." Mercer didn't know how soon this might happen, but when he made his calculations in the mid-1970s, he predicted that if fossil-fuel consumption continued to accelerate, it could begin in 50 years. That is, right about now.

More here. (Warning: lengthy but fascinating article).

Toby said...

"Half the world's population lives within 50 miles of a coastline." (From the link provided by Anonymous above)

Just imagine three and a quarter billion people trying to escape that! We think we have an immigration problem now. 3,250,000,000 will sink the lifeboat.