Thursday, August 13, 2015

Peak Sea Level - 3

Fig. 1 Ice sheet & its ice shelf
I have been working on the SLC software, but I ran into a hard place surrounded by rocks, so I thought I would come up for air to rest.

And to do today's post before it becomes tomorrow.

I am putting this post in this series because I ran across an article by one of Professor Mitrovica's associates who worked on several peer reviewed papers concerning gravity loss as ice sheets melt.

And its impact on sea level rise (SLR) and sea level fall (SLF).

I think I found a flaw in their hypothesis, albeit perhaps a minor one.

The specific assertion they make is that if the W. Antarctica ice sheet melts it will cause SLF near the coast of Antarctica, and outward from there.

So far, so good.

My concern was that they followed that up with "that will stabilize the ice sheet."

That will move the warm water away from contact with the bottom of the ice sheet was perhaps what they were thinking.

Their particular hypothesis is set forth in an article as follows:
"Scientists have long been concerned that the melting of the massive West Antarctic Ice Sheet could become a self-reinforcing process, with the released water raising sea levels, leading to more melting, and so on.

Their concern stems from the fact that much of the land on which the ice rests is actually below sea level, forming a bowl sealed from the ocean by the immense weight of the ice above it. Should seawater infiltrate that bowl, scientists are worried it could float the ice at its edge, starting a runaway collapse that could raise the global sea level as much as 16 feet.

Now, however, Harvard researchers have a rare bit of what passes for good news on the global warming front: If the West Antarctic ice sheet melts, it will have the seemingly contradictory effect of lowering sea levels nearby, actually stabilizing the sheet."
(Harvard Gazette, emphasis added). I thought that might be a misunderstanding on the part of the person who wrote the article, because Natalya Gomez is quoted in the last sentence as also having said:
The gravity-sea level interaction “is not going to halt the collapse of the ice sheet, but it’s going to slow the rate of collapse,” Gomez said.
(ibid). I do also remember Professor Mitrovica saying, in the video in the previous post of
Fig. 2  Undermined ice shelf
this series, that he had good news--the drop in sea level around W. Antarctica would slow down or halt the ice sheet collapse.

But I don't think that is the case.

Notice Fig. 1, a typical graphic which depicts an ice sheet with its ice shelf extended over the ocean water near the coast (that graphic is taken from the second video below which shows "grounding drift").

Now notice Fig. 2 which is a modified version of Fig. 1, showing that if the sea drops in response to a loss of gravity as a result of loss of ice sheet mass, then the ice shelf is likely to lose its support and therefore break away from the ice sheet.

Since the ice shelf is a buttress against the ice sheet flow towards the sea, IMO the glaciers will speed up, not slow down or stop, once the ice shelf buttress is damaged and calved.

The two videos below are concerned with the area of W. Antarctica being discussed today.

Anyway, gotta get back to developing the SLC software now.

The next post in this series is here, the previous post in this series is here.

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