When we looked at the collapse of the Wilkins ice bridge the experts thought it could make the remaining ice unstable. My own expectation since we are heading into winter was that things would ice over for the period.
Well, since last Friday some 270 square miles (700 square kilometers) of ice have dropped into the sea, according to satellite imagery.
The ice shelf which is as big as Jamaica is now expected to lose more.
Over the next several weeks, scientists estimate the Wilkins shelf will lose some 1,300 square miles (3,370 square kilometers) — a piece larger than the state of Rhode Island, or two-thirds the size of Luxembourg.
Almost certainly, this is not just a canary in the coal mine. More like the preamble to the routine melting of the West Antarctic ice sheet as has happened 60 times before in the past few million years.
Anyway, here are the pictures. The first two are from the previous post:
Figure 1: Wilkins ice bridge 31 March, 2009
Figure 2: Collapsed ice bridge 6 April, 2009
This is what it looked like on 27 April:
Figure 3: Wilkins ice shelf 27 April, 2009
Even though it must be dark down there by now, with the European Space Agency satellite we have a ring-side view.
Update: Here’s a zoom in on the Wilkins area from the map at Wikipedia:
For a proper orientation, look at Dorsey Island in Figure 3 above. On this map it must be the island just to the right of the words “WILKINS SOUND”.
OK, for us dummies – is that sea or land-based (sea level rise) ice?
Thanks for keeping it real, Brian!
Ice shelves are by definition floating on the sea but joined to the land. That is they are solid and continouos with land ice, but in the case of Wilkins the 20 metres (60 feet) or so you see above water is the same proportion to the underwater part as for an iceberg. From memory it’s a ninth that you see above water. So they are very thick, normally solid sheets of ice.
Ice shelves buttress land ice, so when they go completely the movement of ice from land to sea speeds up. In the case of Wilkins, I understand there is nothing much behind the ice shelf on land, so this one means nothing directly for sea level rise.
However it is the southernmost ice shelf that has been significantly breaking up and research shows historically that the breakup of ice shelves in Antarctica is in fact the prelude to ice sheet decay if it’s going to happen.
Subject to correction, as always, by people who really know about these things!
It’s already afloat, so it does not matter and it has happened before (as you’ll know, Charcot was circumnavigated in the 19th century by whaling ships). This may be just another impact of the series of major volcanic sub-sea and sub-icecap eruptions from Bryan Coast to Graham Land over the last 2 years.
IT
IT, have a look for the volcanic activity in Figure 14 in this post. from people who would know I understand that the maths on the heat involved doesn’t even come close.
I wasn’t aware of what happened in the 19th century, if indeed it did. But there is a difference between a regional anomaly and a worldwide pattern of warming.
While Wikipedia isn’t necessarily always right, it’s saying Charcot island was discovered in 1910.
Circumnavigation would have been achieved by one of those submarine nineteenth-century whaling ships, no doubt.
I think to get a proper orientation, look at Dorsey Island in the third image above and match it with the island shown well to the right of Charcot on Figure 2 of the previous post.
It’s not unreasonable to say that the whole ice sheet is seriously compromised.
I’ve added a zoomed in map of the Wilkins area from Wikipedia as an update at the end of the post.
LE, further to comment 2, I should have added that when an ice sheet goes any glaciers on the adjacent land speed up. See this image. According to Wikipedia that’s what happened at Larsen B.