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Antarctic Ice Shelf Split – Global Warming Or Volcanic Activity?

Another day, another breathless  “Antarctica is melting” report:

An ice bridge linking a shelf of ice the size of Jamaica to two islands in Antarctica has snapped.

Scientists say the collapse could mean the Wilkins Ice Shelf is on the brink of breaking away, and provides further evidence of rapid change in the region.

Sited on the western side of the Antarctic Peninsula, the Wilkins shelf has been retreating since the 1990s.

The BBC report seems to consciously avoid blaming it on global warming, but does imply the change is recent (and leaves it to you to decide what that means):

“The fact that it’s retreating and now has lost connection with one of its islands is really a strong indication that the warming on the Antarctic is having an effect on yet another ice shelf.”

Since this is a floating ice shelf, its breakaway will have zero effect on sea levels.

The NYT, of course, is not so careful with its coverage:

An ice bridge holding a vast Antarctic ice shelf in place has shattered and may herald a wider collapse caused by global warming, a scientist said Saturday.

While citing both articles, Think Progress naturally choses the more dire pronouncement as its lede.

Of course we’ve been through this before. You may remember the discussion when it first came up almost a year ago to the day, we did some research and discovered, low and behold, that the area where the Wilkins Ice Sheet is located also happens to be the location of some active undersea volcanoes.
wilkins
Notice the ice shelf is on the western side of the peninsula and south of its tip. Now, look at this:

volcano

Well I’ll be – an active volcano very near the shelf which also vents further up the peninsula. I wonder – could that cause a bit of warming in the area?

Last year, the Ice Cap provided a little sanity to the discussion.  Then it was an MSNBC report.  It is essentially no different than thes reports.  In fact it is more of what they don’t say than what they do say the make the news reports suspect. Here’s what Ice Cap said last year:

The [MSNBC] account may be misinterpreted by some as the ice cap or a significant (vast) portion is collapsing. In reality it and all the former shelves that collapsed are small and most near the Antarctic peninsula which sticks well out from Antarctica into the currents and winds of the South Atlantic and lies in a tectonically active region with surface and subsurface active volcanic activity. The vast continent has actually cooled since 1979.

The full Wilkins 6,000 square mile ice shelf is just 0.39% of the current ice sheet (just 0.1% of the extent last September). Only a small portion of it between 1/10th-1/20th of Wilkins has separated so far, like an icicle falling off a snow and ice covered house. And this winter is coming on quickly. In fact the ice is returning so fast, it is running an amazing 60% ahead (4.0 vs 2.5 million square km extent) of last year when it set a new record. The ice extent is already approaching the second highest level for extent since the measurements began by satellite in 1979 and just a few days into the Southern Hemisphere winter and 6 months ahead of the peak. Wilkins like all the others that temporarily broke up will refreeze soon. We are very likely going to exceed last year’s record. Yet the world is left with the false impression Antarctica’s ice sheet is also starting to disappear.

In other words, it is tiny portion of Antarctica which is located in a part of the continent which is most exposed to South Pacific currents and also has “surface and subsurface volcanic activity” to add to any warming. Graphically it looks like this:

temps

So, other than it finally looks like Wilkins may split away, the situation isn’t any more dire than it was last year at this time and seems, instead, to be the work of natural forces that certainly would have a warming effect without the assistance of any sort of “global warming”.

~McQ

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