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Arthur T Knackerbracket has found the following story:
Storm-driven ocean swells have triggered the catastrophic disintegration of Antarctic ice shelves in recent decades, according to new research published in Nature today.
Lead author Dr Rob Massom, of the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Centre, said that reduced sea ice coverage since the late 1980s led to increased exposure of ice shelves on the Antarctic Peninsula to ocean swells, causing them to flex and break. "Sea ice acts as a protective buffer to ice shelves, by dampening destructive ocean swells before they reach the ice shelf edge," Dr Massom said. "But where there is loss of sea ice, storm-generated ocean swells can easily reach the exposed ice shelf, causing the first few kilometres of its outer margin to flex."
"Over time, this flexing enlarges pre-existing fractures until long thin 'sliver' icebergs break away or 'calve' from the shelf front. This is like the 'straw that broke the camel's back', triggering the runaway collapse of large areas of ice shelves weakened by pre-existing fracturing and decades of surface flooding."
Study co-author Dr Luke Bennetts, from the University of Adelaide's School of Mathematical Sciences, said the finding highlights the need for sea ice and ocean waves to be included in ice sheet modelling. This will allow scientists to more accurately forecast the fate of the remaining ice shelves and better predict the contribution of Antarctica's ice sheet to sea level rise, as climate changes. "The contribution of the Antarctic Ice Sheet is currently the greatest source of uncertainty in projections of global mean sea level rise," Dr Bennetts said.
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(Score: 0) by Anonymous Coward on Saturday June 16 2018, @06:01PM (9 children)
And the timing of the rat in the maze isn't measured via pictures either. Here is a picture of a swell:
https://swelllinesmagdotcom.files.wordpress.com/2014/07/inside-aliso-marble.jpg [wordpress.com]
Heres another one:
https://upload.wikimedia.org/wikipedia/commons/e/e0/Easterly_swell%2C_Lyttelton_Harbour%2C_29_July_2008.jpg [wikimedia.org]
There is quite a bit of variation there. I just wanted to see a picture of these swells to understand what they are talking about.
(Score: 2) by janrinok on Saturday June 16 2018, @06:29PM (8 children)
In which case you need to read the research paper that is mentioned in TFS and look at the data there. The data is published so with a bit of judicious searching you should be able to find it.
(Score: 0) by Anonymous Coward on Saturday June 16 2018, @06:41PM (2 children)
I looked at the paper. The closest they come is a couple plots of "significant wave height" and "peak wave period" in the supplements. Not a single picture of a swell.
(Score: 3, Informative) by dry on Sunday June 17 2018, @01:57AM
In deep water, a swell is pretty boring and I'd think, hard to do justice in a picture. Think of a long low amplitude wave.
(Score: 2) by janrinok on Sunday June 17 2018, @07:52AM
As I said, they don't need to photograph the swell as the data collection is automated. However, if you just want to see pictures of swell then Google (Images) has plenty, and the original research paper will usually either contain the actual data that was analysed, or tell you where the data can be found. For the paper to be credible the data has to be available for others to analyse independently.
(Score: 2) by Hawkwind on Sunday June 17 2018, @03:28AM (4 children)
Placing this here as deniers are jumping all threads, but you seem to be familiar with the topic. What is the new part here? I recently saw a talk by a prof from U of W (sorry, only cell phone right now), and he mentioned how increased temperatures below the surface are accelerating calving, and that it was worse in Antartica. This paper seems a modest step regarding the mechanics of an issue already recognized.
(Score: 3, Interesting) by janrinok on Sunday June 17 2018, @08:20AM (2 children)
I'm afraid my knowledge is now somewhat out of date. My take on the paper is that in the past the swell effect was dampened by the sea ice. The sea ice is now significantly less than it was a decade or two back and so the dampening effect is not occurring. As a result, the swell is also reaching further under the glacial ice with sufficient energy to cause the ice to crack and calve more easily and extensively than it used to.
There is nothing new in the actual mechanics of the event, as you correctly point out, but the extent to which it is occurring is increasing over the period of time that measurements have been taking place. Glacial ice can sometimes take millennia to form and the detached ice flows follow the sea currents to warmer climes where they melt. Also, scientists are noting a small but significant increase in the strength of storms and other meteorological conditions that create the swell often thousands of kilometres from where the damage is taking place. Together there is a change which is why the conditions that are being measured today are noteworthy.
I am not claiming that the cause of this combination of conditions is down to any specific factor. It might be something that has occurred many times in the past before we started measuring and recording such phenomena. However, that does not mean it is not occurring now. Denial of the event seems to be pointless as the evidence is there for all to see. As the rise in ocean levels is measurable and there has been no catastrophic flooding recorded over the last few hundred years, it suggests to me that the event is not one that occurs frequently and what we are witnessing today is significant - if only from a position of rarity or uniqueness. Perhaps it will correct itself over time, perhaps it won't. My knowledge of the matter is at a very superficial level and I will leave it to those with significantly more expertise in the subject to identify the causes and possible outcomes of the events we are now seeing.
(Score: 2) by janrinok on Sunday June 17 2018, @08:22AM
s/ice flows/ice floes/
I should have spotted that one!
(Score: 2) by Hawkwind on Monday June 18 2018, @04:31AM
Thanks for the answes! I do have to say number of buoys now measuring the water is pretty impressive, and this article is a good update from those measurements.
Good stuff
(Score: 3, Interesting) by janrinok on Sunday June 17 2018, @08:46AM
An alternative answer to your question - which perhaps puts it more clearly into perspective. It is not the actual mechanics that have changed but the fact that 11,500 years of glacial build has been lost in a relatively short period of time with additional knock-on effects as a result.