Around July 11th a trillion tonne chunk of Larson C ice shelf broke off and become the roughly 2,200 sq mile Iceberg A-68. The news was reported by scientists observing the growing crack through the Project Midas website.
Martin O’Leary a Research Officer at Swansea University and expert in ice flow modeling was quoted and has been re-quoted ad nauseum saying:
“Although this is a natural event and we’re not aware of any link to human-induced climate change, this puts the ice shelf in a very vulnerable position.”
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Larsen C Ice Shelf - February 21, 2017
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Huge Antarctic iceberg finally breaks free - Larsen Ice Shelf, Antarctica
July 12, 2017
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I understand there’s valid reasons for scientists being ultra-conservative in making connections, but that "no link" suggestion is simply weird, pollyannaish even. Reads like it was penned by a Trump team member rather than a dedicated researcher. Or, perhaps it was penned by someone deeply frightened by the Trump Administration and funding concerns.
Before labeling me a scientist basher understand my years worth of blogging has been all about defending the solid integrity of scientists, and the work they have been sharing with a public that has a right to know the unvarnished truth without constantly being deluged by lies, slander and disingenuous distractions into irrelevance.
{PS. Check out the latest news, once again exposing how all this 'Seepage' started:
Utilities Knew: Documenting Electric Utilities’ Early Knowledge and Ongoing Deception on
Climate Change From 1968-2017 http://www.energyandpolicy.org/utilities-knew-about-climate-change/
It’s true, I’m only a high school grad, class of ’73, but I’ve been actively keeping up on climate science developments and global observations ever since. Does that give me the right to lecture experienced professionals on communicating science?
Well if they continue spinning reality into an intellectual parlor game that ignores the existential crisis we have collectively created for ourselves, … if their message sidesteps common sense geophysical interconnections. You bet !
So long as I can support my indictment with rational arguments and valid evidence.
This post will be about the mountain of evidence pointing to this recent calving event being part and parcel of an interconnected global climate engine that is being warmed by society’s fossil fuel burning emissions! It will also spotlight other examples of gratuitous misleading words injected into reports purely for their soothing value and political cover.
Not having every single detail of every dynamic interconnection mapped out in it’s entirety is no justification for ignoring obvious dynamics and cascading consequences.
There is no known mechanism other than current warming that can explain the drum beat of significant ice degradation and calving events being observed along the Antarctic Peninsula. Suggesting that Larson C may be independent of that overall reality, makes no sense.
The rest of this post is a collection of articles and quotes from experts that give an overview of Larson C, A68 and what’s unfolding on Antarctic's cryosphere. However it’s couched, this overview leaves little doubt of what’s happening and that the cause is clearly the cascading consequence of manmade global warming.
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I’m switching to blue {and red} Georgia font for clarity and will start with the July 13th BusinessInsider.com because of it’s splendid wide ranging pictures, maps and schematics put together by Dave Mosher. Opening that link in another tab will help with visualizing the rest of this.
“Antarctica's colossal new iceberg is doomed — here's what will happen next”
Though even here, near the end there’s this gratuitous disclaimer:
“A68's birth is most likely not tied to climate change. But there's a lot of melting ice around the world that researchers have connected to human activity — and that's cause for alarm.”
{Why would the thinning and weakening of Larson C enabling a stress crack to evolve into a major fault line not be related to global warming?
Sure there’s a sequence of mechanical stress, a cascade of dynamic events that may not be directly driven by weather events, still in the end it’s increasing heat driving the show.}
Or this one:
“Our work has highlighted significant similarities between the previous behaviour of Larsen B and current developments at Larsen C, and we have shown that stability may be compromised.” "Others, however, are confident that Larsen C will remain stable.""
The first link is a fascinating and informative early 2014 paper on ice shelf structure and stresses: “Marine ice regulates the future stability of a large Antarctic ice shelf” https://www.nature.com/articles/ncomms4707. Very informative, but:
“We hypothesize that Larsen C ice shelf may suffer a similar fate (to A and B) if it were not stabilized by warm and mechanically soft marine ice, entrained within narrow suture zones.”
Following a brief introduction to marine ice-bearing suture zones and their anomalous physical properties, we argue, third, that such zones presently prevent the loss of Larsen C’s frontal portion and by implication, therefore, stabilize the whole ice shelf.” {That didn’t work out.}
The second link “The safety band of Antarctic ice shelves” https://www.nature.com/nclimate/journal/v6/n5/full/nclimate2912.html finished their introduction with:
“In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large ‘passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg8 will be unlikely to instantly produce much dynamic change.”
“Instantly”? Okay, sure probably not instantly. But, the weeks and seasons speed by. Why can’t we face that in our warming world this massive ice shelf is not going to be stabilizing.
In struggling to understand the scientists wording I’m getting the impression that they’ve divorced internal ice sheet stress fields and stress-flow angles from the warming from above, below and within as the entire ice mass slowly distributes the absorbed heat throughout its structure. At least until they can map every vector and gradient.
But that doesn't make any sense. What’s going on?
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Now I want to look back to 1995, a time when I know that we already knew that our profligate fossils fuels burning was going to have serious consequences. We knew it would add ‘insulation’ to our atmosphere and thus warm up our global heat and moisture distribution engine and that this warming was going to inevitably permeate all crevasses and increasingly alter our Earth’s biosphere and weather patterns. Simple physics, no getting around it.
The Devil’s Bargain was that it would take a few decades for the impacts to really become harmful thus obviously noticeable and by then the die would be cast. A few decades, half century, no one could say for sure - thus it was easy to set it aside and love the good times constantly striving to consume more, more, more.
I was over twenty years out of high school when things started getting noticeable and was laughed at for being concerned about this:
January 5, 1995
Events in the Northern Larsen Ice Shelf and Their Importance
Dr. Ted Scambos and Christina Hulbe
… Field expeditions conducted in the 1990's have routinely found extensive surface melting (1), summer melt ponds were observed in satellite images for several years prior to the breakup (see figure), and retreat of the far northern shelf front is well-documented in satellite images (2). It is probable that thinning and weakening due to extreme summer surface melting led to the disintegration of the far northern part of the shelf. …
… For example, the Miller Ice Shelf has been receding since about 1974 (3) and the Wordie Ice Shelf broke apart in the 1980's (4). Both ice shelves are on the western side of the Peninsula, where local warming has been documented at British Antarctic Survey bases (4). Temperatures have increased an average of 2.5 C (4.5 degrees Fahrenheit) since the 1940's. In all likelihood, these events are linked.
In the late 1970's, Mercer (5) noted the correspondence between the distribution of ice shelves and mean annual air temperature isotherms around Antarctica. He suggested that the -4 degrees Celsius (25 degrees Fahrenheit) isotherm provides an upper limit for ice shelf survival. Both the Northern Larsen and Wordie ice shelves were near this limit. …
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Speaking of Dr. Mercer, here’s a relevant paper published three years after the above.
Followed by a few other informative papers for further background.
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West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster
J. H. MERCER
Institute of Polar Studies, The Ohio State University, Columbus, Ohio 43210
Nature 271, 321 - 325 (26 January 1978); doi:10.1038/271321a0
“If the global consumption of fossil fuels continues to grow at its present rate, atmospheric CO2 content will double in about 50 years. Climatic models suggest that the resultant greenhouse-warming effect will be greatly magnified in high latitudes. The computed temperature rise at lat 80° S could start rapid deglaciation of West Antarctica, leading to a 5 m rise in sea level.”
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Changes in ice-shelf buttressing following the collapse of Larsen A Ice Shelf, Antarctica, and the resulting impact on tributaries
Sam Royston, G. Hilmar Gudmundsson
British Antarctic Survey, Cambridge, UK
Journal of Glaciology (2016), 62(235) 905–911
ABSTRACT. The dominant mass-loss process on the Antarctic Peninsula has been ice-shelf collapse, including the Larsen A Ice Shelf in early 1995. Following this collapse, there was rapid speed up and thinning of its tributary glaciers. …
The model results show an instantaneous twofold increase in flux across the grounding line, caused solely from the reduction in backstress through ice shelf removal. This demonstrates the importance of ice-shelf buttressing for flow upstream of the grounding line and highlights the need to explicitly include lateral stresses when modeling real-world settings.
We hypothesis that further increases in velocity and flux observed since the ice-shelf collapse result from transient mass redistribution effects. Reproducing these effects poses the next, more stringent test of glacier and ice-sheet modeling studies.
1. INTRODUCTION
The Larsen Ice Shelf, located to the east of the Antarctic Peninsula, has exhibited a persistent, stepped retreat since aerial observations began in the 1950s, {Yes the warming was already happening} with significant retreat since 1986 …
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The Larsen C Ice Shelf growing rift
Posted on 19/06/2017 - AntarcticGlaciers.org
Throughout the last few decades, it has shown little evidence of climate-driven retreat, with variations in the ice front following normal fluctuations.
However, the ice shelf has been thinning, with surface lowering observed by analysis of satellite images, likely due to basal melting and enhanced melting of snow on the ice-shelf surface. {What’s up with that? Like the thinning isn’t caused by climate-driven warming? Why the implied distinction?} A large and growing rift at its front suggests it will soon calve the largest ever recorded iceberg.
Ice shelf collapse on the Antarctic Peninsula
This seemingly stable behaviour contrasts with the ice shelves to the north, the Prince Gustav, Larsen A and Larsen B ice shelves, which have disintegrated over the last few decades. Prince Gustav Ice Shelf retreated throughout the second half of the 20th Century, before rapidly disintegrating in 1995. Larsen A disintegrated in 1995, following a previous period of stability from the 1980s. 2000 km2 of ice were lost in just a few weeks, breaking up into thousands of ice bergs that were discharged into the Weddell Sea. {Why not a word about the structural details that explain the contrasts between those ice shelves?}
Larsen B collapsed even more dramatically in 2002, with only 2400 km2 of its original (in 1963) 12000 km2 remaining. This ice shelf was likely present for the entire last 10,000 years, and this is probably the first time it has collapsed. …
Ice shelves buttress and support glaciers on land …
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Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning
P. R. Holland, A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming
Published: 13 May 2015
Abstract. The catastrophic collapses of Larsen A and B ice shelves on the eastern Antarctic Peninsula have caused their tributary glaciers to accelerate, contributing to sea-level rise and freshening the Antarctic Bottom Water formed nearby.
The surface of Larsen C Ice Shelf (LCIS), the largest ice shelf on the peninsula, is lowering. This could be caused by unbalanced ocean melting (ice loss) or enhanced firn melting and compaction (englacial air loss). Using a novel method to analyse eight radar surveys, this study derives separate estimates of ice and air thickness changes during a 15-year period.
… The ice loss is much larger than the air loss, but both contribute approximately equally to the lowering because the ice is floating.
The ice loss could be explained by high basal melting and/or ice divergence, and the air loss by low surface accumulation or high surface melting and/or compaction. The primary estimate therefore requires that at least two {Ultimately AGW related} forcings caused the surveyed lowering.
Mechanisms are discussed by which LCIS stability could be compromised in the future. The most rapid pathways to collapse are offered by the ungrounding of LCIS from Bawden Ice Rise or ice-front retreat past a "compressive arch" in strain rates. Recent evidence suggests that either mechanism could pose an imminent risk. …
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Here’s a report I found poorly presented
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An Ice Shelf Is Cracking In Antarctica, But Not For The Reason You Think
January 16, 2017 - NPR
"A lot of things are going on deep inside the ice,” {including migration of heat} says Adrian Luckman, a glaciologist at Swansea University in the U.K. He's also leading a project to track changes in the ice shelf.
He says climate change is certainly influencing this region. Larsen C used to have two neighbors to the north, Larsen A and Larsen B. As the air and water warmed, those ice shelves started melting and then splintered into shards in 1995 and 2002.
But the crack in Larsen C seems to have happened on its own, for different reasons. {For different reasons than A and B that is.
But the implication is "different reasons" other than global warming. Okay B was hit by extreme heat wave so the AGW was more ‘in your face’ - but the slower absorption and stress transformations are every bit as much driven by the overall impact of relentless warming of the Antarctic Peninsula these past decades.}
"This is probably not directly attributable to any warming in the region, although of course the warming won't have helped," says Luckman. "It's probably just simply a natural event that's just been waiting around to happen.” {I am sorry but that’s inane. “Not directly”? “Simply a natural event”?
What the hell is that supposed to tell us?
Waiting around for what to make it happen?
Perhaps some warming to loosen things up?}
The wording implies wind and ocean currents are the same as they ever were. Not true.
Think about it, every aspect of Antartica Peninsula is being influenced by the warming. Simply because Larson B was a surface warmed slush disintegration of sorts and A68 was a clean stress crack cleaving event, doesn’t mean warming wasn’t the driver. Distal perhaps, but still the cause of the chain of events leading up to this calving.
Larsen C has a bunch of cracks. All ice shelves do. This particular crack has been around since at least the 1960s. The unusual part is that in 2014, this crack — and only this crack — started growing in spurts. Why?
"Well, that is a little bit of a mystery and that's why it drew itself to our attention,"
Basically these sentences leave the impression of removing heat from equation. They imply that structural weakness, strains, stress and cracks are independent of warming from above, below, and within.
They also sidestep the mechanical stresses of AGW driven changes in wind and ocean currents and intensity, all of which is driven by global warming.
The only mystery is why the stresses and strains choose that particular pathway!
Warming ocean current melting away at the base of the ice shelf and surface warming transforming the surface and probably a bit of softening in the interior of the ice shelf. To categorize that as: “it’s just been waiting around to happen” is bizarre in the extreme.
For me minimizing the obvious warming connections is an act of dishonesty.
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Scientists report large-scale surface melting event in Antarctica during 2015-16 El Niño
June 15, 2017 - University of California - San Diego
The science team conducting the ARM West Antarctic Radiation Experiment (AWARE) led by researchers at Scripps Institution of Oceanography at the University of California San Diego reports that the melting caused by warm air bearing moisture and extensive cloud cover was likely delivered by El Niño over the ice sheet. Melted snow was spotted over most of the Ross Ice Shelf, a thick platform of floating ice that channels about a third of the ice flowing from the West Antarctic Ice Sheet into the ocean.
The study, "January 2016 extensive summer melt in West Antarctica favoured by strong El Niño," was led by AWARE scientist Julien Nicolas of Ohio State University and appears in the June 15 issue of the journal Nature Communications.
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Warm winds: New insight into what weakens Antarctic ice shelves
April 25, 2017 - British Antarctic Survey
New research describes for the first time the role that warm, dry winds play in influencing the behaviour of Antarctic ice shelves. Presenting this week at a European conference scientists from British Antarctic Survey (BAS) explain how spring and summer winds, known as föhn winds, are prevalent on the Larsen C Ice Shelf, West Antarctica and creating melt pools. The Larsen C Ice Shelf is of particular interest to scientists because it of the collapse of Larsen A in 1995 and Larsen B in 2002. …
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Stronger winds heat up West Antarctic ice melt
July 17, 2017 - University of New South Wales
New research published today in Nature Climate Change has revealed how strengthening winds on the opposite side of Antarctica, up to 6000kms away, drive the high rate of ice melt along the West Antarctic Peninsula.
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The ABCs of Antarctic Ice Shelf Melting
But on the Antarctic Peninsula — the arm that stretches northward from the continent toward South America — rising air temperatures are impacting the ice.
The region is a global hotspot for warming, with temperatures that have risen by about 5°F in the past 50 years, while the globe as a whole has warmed by about 1.3°F.
A study published last year pointed the finger at this warming as the reason for the Larsen B collapse, arguing that the elevated temperatures caused excessive surface melt that led to significant cracks in the ice.
When it comes to the Larsen C shelf, both warming air and melting ice are potential culprits. The surface of the ice shelf has been getting lower and lower in recent decades, but it was unclear what the source of that lowering was. It could be that the layer of compacted snow at the surface, called firn, was melting and compacting further still, or it could be that ice from the bottom of the shelf was melting, causing the height of the glacier to adjust. Or it could be some combination of the two. …
What exactly is causing the ice loss and firn compaction is still not fully known. {Maybe we don’t know the exact details of specific mechanisms, but we know warming is what’s providing the energy for the transformations that are occurring and we know where that warming is coming from!}
It’s possible the firn is melting and compacting because of warmer air, or it could simply be that less snow is falling to build it up. For the ice loss, which is the larger force affecting the shelf, it could {What’s with the “could”?
How much does it require before you can say THIS IS HAPPENING?} be that the ocean waters are melting the ice, or that the flow of the ice is changing.
How much does it require before you can say THIS IS HAPPENING?} be that the ocean waters are melting the ice, or that the flow of the ice is changing.
“There’s all kinds of wacky possibilities,” Holland said. “It’s really tough to figure out what it is.” … {Why aren’t we allowed to assume it’s because of warming?
Why invoke “wacky possibilities”?}
I get so depressed reading stuff like that coming from such an expert, another one whom I’ve been learning from for years. It’s so disheartening it literally churns my stomach. But jezz, what are these “wacky possibilities” being entertained?
How many of those “wacky possibilities” remove AGW as the ultimate cause and driver?
If as I suspect those “wacky possibilities” are about specific mechanisms and surprising interconnections, then say so, but acknowledge the overall reality we are dealing with.
I just realized it’s as if scientists are like the salesman that’s never learned how to close the deal. Is that why so many keep circling closer and closer to the answer without ever clearly declaring it.
Isn’t there a place for pragmatic declarations?
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The 1-2 punch to the Larsen C makes the ice shelf more vulnerable, particularly with some other worrying signs. The biggest threats to the ice shelf’s stability, Holland thinks, come from indications it could unpin itself from an island that helps slow its flow, as well as a rift that has formed across the ice. If that rift reaches more vulnerable parts of the ice sheet, it could seriously destabilize it.
Here’s another example. For what rational reason was “could” injected into that sentence?
If another rift reaches more vulnerable parts of the ice sheet it damned well will destabilize another sizable section of the ice sheet, which will lead to further degradation of the ice sheet. Try it out with a block of ice and a warm day, there’s only one direction it’s going.
If it lifts off it’s island mooring and becomes a floater, of course it’s going start breaking up, what possible other source of stability could step in to protect it from ocean and wind currents?
The certainty of the direction and it’s cascading impacts is simply unavoidable physics - even if it remains politically deniable.
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John Abraham a scientist and communicator of the highest caliber, also a personal hero for his thoughtful takedown of the fraud “Lord” Monckton
( http://www.stthomas.edu/engineering/jpabraham/ ) and his subsequent excellent articles at the UK Guardian.
( http://www.stthomas.edu/engineering/jpabraham/ ) and his subsequent excellent articles at the UK Guardian.
He wrote an illuminating article a month before A-68 complete separation:
Imminent collapse of a portion of Larsen C ice shelf hammers home reality of climate change
… Perhaps a quotation from a seminal work on Antarctic ice sheets best sums up the situation. In a 1978 paper, John Mercer from the Institute of Polar studies concluded:
“One of the warning signs that a dangerous warming trend is under way in Antarctica will be the breakup of ice shelves on both coasts of the Antarctic Peninsula, starting with the northernmost and extending gradually southward. These ice shelves should be regularly monitored by Landsat imagery.”
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“Why is part of the ice shelf going to break off and collapse into the ocean? Since large calving events are so rare, and since our measurements in and around ice shelves don’t go back in time far enough, it’s hard to say whether this is a natural progression, variability, or a result of human activity (or more likely a mixture of both).
One reason may be human-caused warming, which has led to melting from both above and below in nearby areas and is widely accepted to have contributed to the disintegration of nearby Larsen A and Larsen B. {Is injecting “MAY” into this paragraph justified? Where is the maybe in extra heat soften and melting ice? } The Western Antarctic (the parts south of the US) is warming quite quickly, faster than most of the planet. In addition, warmer waters can reach underneath the ice shelf and can melt it from below.”
That being said, there are vigorous discussions within the scientific community about how much, if any {?}, of this can be attributed to humans. {If not AGW what’s that leave?} Some scientists think there is strong connection; others are much less sure and see little or no evidence that humans are the cause. {How’s that possible when all the studies reflect warming and warming induced alteration of previous patterns?}
From my vantage point, part of this relates to our limited ability to measure what’s going on, and part of this is a common sticking point of whether an absence of evidence is evidence of an absence. {It’s also a map vs. territory question.}
{What about acknowledging that other biggest possibility: Pure Fear of the inevitable Right Wing attack dogs?}
I’ve heard from multiple differing views on this very topic while preparing this post. From my research and experience in climate science as well as in many other areas of research where risk analysis and evidence are weighed, we should assume that human-caused warming is having an effect. {Amen.}
We can measure the incredible amount of heat that is being stored in the oceans as well as the increase in temperatures that have occurred over the Western Antarctica and changes to the ocean currents in the region – there must be some implications to the health of the ice. {My point exactly.
The question is, why do so many who know better continue dancing around that with contrived avoidance of the obvious?}
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Trouble at Totten
Can we please wake up! How can a warming planet not impact every aspect of its geophysical systems and that heat and moisture distribution engine we call weather?
3 comments:
Oh the silence, how well I know it.
I wonder if any of this makes sense to anyone out there? I know a few are looking in.
If it's totally gibberish, wish someone could describe to me why - in a constructive manner.
I finally got around to emailing John Abraham to let him know that I quoted from his UK Guardian article and critiqued some of his wording. I'll admit after the derision, and angry slammed doors, I've received these past months, I was worried that I was about to pissed of yet another hero of mine. Boy was I in for a surprise. He's even given me permission to share his words.
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From: Abraham, John P.
Mail to: citizenschallenge at gmail.com
Sent: Wednesday, July 26, 2017 1:13 PM
Subject: Hello, fyi quote from your 6/14/17 A-68 article.
Peter
Thanks. You should know that after I drafted that article, folks from the MIDAS project got quite upset and asked me to change it (inappropriately in my mind).
I softened some of the language to try to satisfy them (they were not satisfied). Anyways, I believe there is a connection to climate change and they believe, without justification there is not.
Their view is not supported and is contradicted by others with more expertise than they. Nevertheless this is a sore spot for me because they tried to bully me to eliminate the connection to human warming.
Long story short, please feel free to quote me and don’t worry if you think I should use stronger language.
John P. Abraham
I added the bold highlights and paragraph breaks for clarity.
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"Imminent collapse of a portion of Larsen C ice shelf hammers home reality of climate change"
John Abraham - June 12, 2017
https://www.theguardian.com/environment/climate-consensus-97-per-cent/2017/jun/12/the-larsen-c-ice-shelf-collapse-hammers-home-the-reality-of-climate-change
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