2nd Highest Subantarctic Glacier Advance
Of Last 1,000 Years Occurred 50 Years Ago
Yesterday we learned that a giant iceberg just split off from the Antarctic Peninsula.
Most media outlets were uncharacteristically mild with their declarations of concern. Even The Guardian pointed out that the breakup of the ice is naturally occurring, glaciologists are “not unduly concerned about it“, and while the event “might look dramatic, experts say it will not itself result in sea level rises.”
Rolling Stone‘s Jeff Goodell, on the other hand, was not quite so apt to dismiss the importance of the Antarctic ice “crack-up“. He insisted that there is a certain big-deal connection between the calving of the Larsen C ice shelf and both catastrophic sea level rise…
“Given that Antarctica contains enough ice to raise sea levels about 220 feet … the break-up for Larsen C is certainly a big deal.”
…and human-caused “cooking the planet”.
“It is also well-timed politically. Larsen C has broken off just a month or so after President Trump withdrew the U.S. from the Paris climate agreement, when people around the world are wondering just how much time we have left before the climate spins out of control – and what to do about it. A story in New York magazine about how climate change is cooking the planet kicked up a lot of debate about the usefulness of fear in inspiring political change. Meanwhile, the responsibility for the Larsen C crack-up is already being doled out: Climate activists have launched a campaign to rename the now-liberated Larsen C ice shelf as the Exxon Knew 1 iceberg.”
Scientists: The Antarctic Peninsula Has Been Rapidly Cooling Since 1999
Apparently Jeff Goodell hasn’t been keeping up with the latest cryosphere science.
It is now well established in the scientific literature that the Antarctic Peninsula – the location of the Larsen C ice break-up – has been cooling since the 21st century began. In fact, the Antarctic Peninsula as a whole is cooler now than it was in 1979 (+0.32 °C per decade for 1979-1997, but -0.47 °C per decade during 1999-2014).
Glacier retreat in the region has begun to slow down or shift to surface mass gains.
And the ocean surrounding Antarctica as a whole (the Southern Ocean) has also been cooling since 1979, consistent with the overall trend of sea ice growth during this time period.
Turner et al., 2016
“Here we use a stacked temperature record to show an absence of regional [Antarctic Peninsula] warming since the late 1990s. The annual mean temperature has decreased at a statistically significant rate, with the most rapid cooling during the Austral summer.”
Oliva et al., 2017
“However, a recent analysis (Turner et al., 2016) has shown that the regionally stacked temperature record for the last three decades has shifted from a warming trend of 0.32 °C/decade during 1979–1997 to a cooling trend of −0.47 °C/decade during 1999–2014. … This recent cooling has already impacted the cryosphere in the northern AP [Antarctic Peninsula], including slow-down of glacier recession, a shift to surface mass gains of the peripheral glacier and a thinning of the active layer of permafrost in northern AP islands.”
Fan et al., 2014
“Cooling is evident over most of the Southern Ocean in all seasons and the annual mean, with magnitudes approximately 0.2–0.4°C per decade or 0.7–1.3°C over the 33 year period [1979-2011].”
Comiso et al., 2017
“The Antarctic sea ice extent has been slowly increasing contrary to expected trends due to global warming and results from coupled climate models. After a record high extent in 2012 the extent was even higher in 2014 when the magnitude exceeded 20 × 106 km2 for the first time during the satellite era. … [T]he trend in sea ice cover is strongly influenced by the trend in surface temperature [cooling].”
New Paper Indicates Subantarctic Glacier Retreat Higher In Late 1700s, 1100-1550 AD
A new scientific paper reveals that modern rates of glacier recession – including the recent fate of the Larsen C ice shelf – are well within the range of natural variability.
Van der Bilt et al. (2017) have produced a glacier reconstruction for Southern Ocean islands near Antarctica (South Georgia) indicating glacier recession was more pronounced than today during the late 18th century, and that the second highest glacier advance of the last 1,000 years occurred in the 1960s and 1970s. Only the peak glacier advances of the late 1600s were more extensive than the advances of ~50 years ago.
Similar to the recent Antarctic Peninsula and Southern Ocean cooling and nearly 4 decades of sea ice growth described above, this millennial-scale record of glacier retreat and advance supports the position that humans and variations in carbon dioxide concentrations do not play an influential role in determining the fate of polar ice.
Van der Bilt et al., 2017
Late Holocene glacier reconstruction reveals retreat behind present limits…
“Regional palaeoclimate evidence from the adjoining Southern Ocean region also reveal contemporaneous shifts. For example, reconstructed sea surface temperatures (SSTs) west of the Antarctic Peninsular rose 3 °C in less than a century (Shevenell et al., 2011). … Following the termination of a Late Holocene glacier maximum around 1250 cal a BP, warming created conditions unfavourable for glacier growth during the regional expression of an MCA [Medieval Climate Anomaly] between 950 and 700 cal a BP (Villalba, 1994). From 500 cal a BP [years before present], the Hamberg overspill glacier rapidly retreated behind its present-day position, possibly driven by local warming and/or major shifts in regional atmospheric and oceanic circulation patterns (Moy et al., 2008; Shevenell et al., 2011; Abram et al., 2014; Foster et al., 2016).”
To further put yesterday’s ice “crack-up” news into a long-term context, scientists have found there was a widespread (∼280,000 km2 ) collapse of the “world’s largest” ice shelf that occurred between 4,000 and 1,500 years ago. Retreat rates averaged about 10 kilometers per century during this period.
Of course, this ice sheet collapse occurred while CO2 concentrations hovered near a stable 275 parts per million (ppm), which is about 130 ppm lower than today’s CO2 levels.
Succinctly, the Larsen C ice shelf calving event is not unusual, unprecedented, or even remarkable in the context of Antarctica’s long-term natural variability.
Yokoyama et al., 2016
Widespread collapse of the Ross Ice Shelf during the late Holocene
“The Ross Sea is a major drainage basin for the Antarctic Ice Sheet and contains the world’s largest ice shelf. Newly acquired swath bathymetry data and sediment cores provide evidence for two episodes of ice-shelf collapse. Two novel geochemical proxies, compound specific radiocarbon dating and radiogenic beryllium (10Be), constrain the timing of the most recent and widespread (∼280,000 km2) breakup as having occurred in the late Holocene. … Breakup initiated around 5 ka, with the ice shelf reaching its current configuration ∼1.5 ka. In the eastern Ross Sea, the ice shelf retreated up to 100 km in about a thousand years. Three-dimensional thermodynamic ice-shelf/ocean modeling results and comparison with ice-core records indicate that ice-shelf breakup resulted from combined atmospheric warming and warm ocean currents impinging onto the continental shelf.”
I suppose it would do no good to point out that if floating ice melts then the sea level does not rise at all. Some people do enjoy a disaster tale.
No, it would do no good to point that out. These people actually believe that humans are the cause of catastrophic sea level rise, and we can decide how much or how little glaciers melt or sea levels rise by burning more or less fossil fuels.
I am amazed to hear that Mr. Trump has the power to cause the ice shelf to calve (according to Rolling Stone) just by the the political act of withdrawing from the Paris accords. I bet he did not know he had that power.
Especially since the crack that started the calving started about 100 years ago, ie., well before he was born.
Jun 15, 2017 HAHA!!! GLOBAL WARMING STUDY CANCELED, THE REASON WILL HAVE YOU ROLLING ON THE FLOOR LAUGHING!!!
American Lookout reports, In a perfect example of irony, a scientific research study that intended to study global warming was cancelled after encountering large amounts of ice.
https://youtu.be/MNn7lkO_dkM
Calving is caused by Increasing Ice Mass and nothing to do with temperatures, Goodell knows nothing.
Ice gets pushed down and outwards over the sea. Ice being pushed exerts pressure on the ice flowing behind. Increased calving removes that ice, lowering the pressure, causing increased flow rate. This mechanism stops when no more ice is floating on the sea (max flow rate achieved). It largely depends on the temperature of the water.
On the contrary, it largely depends upon snow fall in the interior; this is the force that you describe in the first sentence of your comment.
The greater the snow fall, the more calving that has to take place. One sees this process very clearly in Greenland.
That’s true, but the less ice that needs to be pushed the greater the speed at which ice will be pushed into the sea by the snow/ice masses behind it. Thus calving of large ice fragments causes acceleration of the ice behind it.
Except the ice shelf broke AWAY from the glacier, it was not pushed. That is very obvious from the fact that the crack has been forming for ages. Pulling away, NOT being pushed.
I take it you flunked basic mechanics, as well as science and physic, hey, seb.
Or do you just INVENT contrary anti-science nonsense on purpose, as part of your child-minded trolling?
The Western Antarctic Peninsula is today several degrees cooler than it was during the Medieval Warm Period:
https://i2.wp.com/notrickszone.com/wp-content/uploads/2017/05/Holocene-Cooling-Western-Antarctic-Peninsula-Browne-17-1.jpg
https://notrickszone.com/wp-content/uploads/2017/03/Holocene-Cooling-West-Antarctica-Shevenell-2011.jpg
So why do you believe that events like this (calving) are caused by human CO2 emissions?
You two … always good for some strange arguments 😉
AndyG55,
what are you even talking about? Of course, the ice gets pushed by the ice behind it. Once a larger than usual iceberg calves it makes room for the ice behind it … which accelerates into the “gap”.
You’ll see.
Kenneth,
don’t distract! Just talking about what happens after an icebergs calves. Nobody is saying anything about human CO2 causing any calving.
SebastianH, I am quite capable of deciding for myself what I can write about…especially in a reply to someone else in a comment thread on an article that I authored. “Don’t distract!” is condescending and rude. A little more humility would be welcome. You are a guest here; perhaps you should act like one.
They’re calling it the Exxon Knew 1 iceberg…and tying it to the U.S. withdrawal from the Paris Agreement. And they believe calving will cause sea levels to rise. Perhaps you should actually read the articles before you begin commenting on them.
Stop distracting with your anti-science fantasies, seb-t.
Gravity pulls.
Are you really so mechanically illiterate that you can’t see that this recent glacier was not pushed, but cracked from the forces of gravity.
Its bizarre that you just keep making up your own anti-science interpretations of everything, regardless of reality.. !!
Oh, and for those that don’t know, Here is a graph of the Total Antarctic Ice Mass since 1900.
https://s19.postimg.org/fqrsmq8oj/Antarctic_ice_mass2.png
“You’ll see”
In a vain attempt to educate seb-t,
the Larson C is not a glacier, its an extremely thick ice shelf.
http://inspimundo.com/wp-content/uploads/2017/02/5060238_6_6cc5_la-progression-de-la-faille-dans-la-barriere_99a8598b6daf87c0f1c241bc18070d2c.png
Oh come on you two …
“Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf”:
http://web.ist.utl.pt/~nuno.j.aniceto/documents/stuff/documents/RignotetalGRLPeninsulaAccel.pdf
@Kenneth specifically: distracting is rude, especially towards a guest. You do this all the time … and suddenly the discussion turns into a completely different one and goes back and forth with no progress and the original point gets lost.
Iceberg calving causes the ice behind it to accelerate. Ice that wasn’t floating before enters the sea at a greater speed than before. While this causes a short term sea level rise it would only cause a permanent rise if the land ice mass permanently decreases. The end.
Do you agree or disagree with that mechanic? Has that anything to do with how “they” (who cares?) named the iceberg?
This is just asinine. As I’ve now written twice, I wasn’t even directing my comment at you.
My original comment about the 260 feet of ice growth between 1942 and 1988 (WWII planes) was directly in response to this comment:
Snowfall on the interior of Greenland was what prompted my comment about…snowfall on the interior of Greenland (where the WWII planes emergency-landed). I was supporting Richard Verney’s comment about calving significantly resulting from ice mass gains, of which there was plenty in Greenland during the 1940s to 1980s. Calving on Greenland occurs routinely and in large part due to the massive growth on the interior.
So your entire complaint about me “rudely” distracting you from the topic at hand is based on your own erroneous assumption that I was directing my comment at you.
The arrogance and rudeness that you exhibit here is breathtaking.
According to real scientists, iceberg calving is significantly caused by thickening ice, as thicker ice shelves are heavier and more prone to fissure and break off. This would seem to support the original comment here (as well as the ice sheet thickening comment I was originally supporting with the “Glacier Girl” example). Will you allow me to provide scientific support for what he wrote, or will you again complain that I am engaging in rude distractions?
—
Christman et al., 2016
https://epic.awi.de/40947/1/viscous-and-viscoelastic-stress-states-at-the-calving-front-of-antarctic-ice-shelves.pdf
Wesche and others (2013) provided a classification of the surface types of calving fronts in Antarctica. They found that 7.4% of the ice-shelf fronts have no surface structures as for example, crevasses. For these ice shelves, calving presumably happens due to bending stresses based on the boundary disturbances or the formation of giant tabular icebergs. Larour and others (2004) discussed calving events near Hemmen Ice Rise on the Ronne Ice Shelf, Antarctica. Some of these events could also be explained by bending due to the boundary disturbance at the ice front. This bending leads to longitudinal surface stresses and results in the fracture of ice and the calving of icebergs. … [T]he stress maximum directly depends on the size of the freeboard and increases linearly with the thickness of the ice shelf. Twice the thickness leads to a doubling of the maximum stress value. … [T]he stresses increase with the thickness, i.e. thicker ice shelves are more prone to calving by bending than thinner ice shelves.”
—
I actually do care that journalists on your side actually believe that fossil fuels (Exxon) caused the ice shelf to calve. This is alarmist misinformation that too often gets passed off as real science. Would you agree it is irresponsible for the Rolling Stone to link fossil fuels and catastrophic sea level rise to this naturally-occurring calving event? Or do you support this tactic?
See, they were PULLED, not pushed.
seb-t’s make believe science, yet again proven WRONG by real science.
Struggling to remember one tiny thing this little trollette has ever managed to get correct ?? !!!!
Your comment is a reply to my comment, not the one above. And you ask me at the end “So why do you believe that events like this (calving) are caused by human CO2 emissions?”
How is that not directed to me? It’s you trying to steer the discussion in another direction and that’s rude.
… that thread is below this one. Here you are trying to distract from the topic at hand: calving affecting the ice behind it.
What happens when ice shelfs collapse: http://web.ist.utl.pt/~nuno.j.aniceto/documents/stuff/documents/RignotetalGRLPeninsulaAccel.pdf
Alarmist misinformation like that “peer reviewed paper” that attributed all global warming to data adjustment? Turns out that it’s false … but you skeptics praised it as if all your dreams have come true at once … http://www.snopes.com/climatology-fraud-global-warming/
Nope, I don’t think the Rolling Stone is correct on this one. But it doesn’t really matter to the topic at hand, does it?
The original statement and reply was:
To which you added: “The Western Antarctic Peninsula is today several degrees cooler than it was during the Medieval Warm Period: [Links]
So why do you believe that events like this (calving) are caused by human CO2 emissions?”
How is that not distracting?
@AndyG55:
Have you ever played Jenga? The lower blocks are pushing up against the blocks from above. What would happen if you could pull all blocks on the bottom level at once (calving)? Gravity accelerates the upper blocks downwards (ice behind accelerating) until the tower is resting on the table again. And so on.
SebastianH, the original post in the thread was this:
AC Osborn: “Calving is caused by Increasing Ice Mass and nothing to do with temperatures, Goodell [who wrote that the calving could be linked to fossil fuels] knows nothing.”
So the original poster wrote that the mechanism has nothing to do with temperatures. You wrote that the mechanism “largely depends on the temperature of the water”.
In response to those comments, I wrote that if (warmer) temperatures (caused by fossil fuel emissions) are the determining factor in ice shelf fissure and break off, why is the AP several degrees cooler now than during the MWP? That was the context of that on-topic comment. (I read messages from the queue in WordPress, which are not in the order in which they appear in comment threads that you see. Therefore, I assumed you were referring to my Greenland WWII planes comment.)
After apparently not having even read the article before commenting, you wrote: “Nobody is saying anything about human CO2 causing any calving.”
Jeff Goodell thought it correct to link human CO2 to calving (and catastrophic sea level rise).
My comments regarding ice thickening on the interior of Greenland leading to calving (the Glacier Girl reference) was in response to Richard Verney’s comment.
The topic at hand is the subject of this article (that you apparently didn’t read) and the original comment in this thread: the extent to which temperatures/human activity affect calving vs. increasing ice mass affects calving. My replies were both to the temperature factor–>calving and ice mass gains factor–>calving.
As demonstrated by scientists discussing mechanisms, the original poster would appear to be correct about “Increasing Ice Mass” as a significant cause of calving.
—
Christman et al., 2016
https://epic.awi.de/40947/1/viscous-and-viscoelastic-stress-states-at-the-calving-front-of-antarctic-ice-shelves.pdf
“[T]he stress maximum directly depends on the size of the freeboard and increases linearly with the thickness of the ice shelf. Twice the thickness leads to a doubling of the maximum stress value. … [T]he stresses increase with the thickness, i.e. thicker ice shelves are more prone to calving by bending than thinner ice shelves.”
—
I actually do care that journalists on your side actually believe that fossil fuels (Exxon) caused the ice shelf to calve. This is alarmist misinformation that too often gets passed off as real science.
So can you explain why you think data manipulation, peer-reviewed vs. not peer-reviewed, and snopes (!) has something (anything) to do with the substance of this article: that journalists on your side deceptively link Exxon, the U.S. exit from the Paris accord, human-caused climate change, and catastrophic sea level rise to ice shelf fissures in Antarctica? How is this not a “distraction”?
Oooh, Jenga. Now that’s an on-topic analogy.
Yet another numb-minded analogy from seb-t.
Why do you always resort to those irrelevant idiocies when you run out of your other farcical arguments?
The Larson C shelf broke from mechanical bending.. It was PULLED, not pushed from behind.
The mechanics of the formation of the crack show that to be the case.
You FAILURE to comprehend ANY sort of basic physics makes me wonder if you ever attended even junior high.
I just wanted to point out that you then just clicked on the wrong reply link. That also explains why your comments sometimes appear in between older comments (which makes it difficult to notice them outside the comment RSS feed) and why you switch the topic or write about unrelated things in a thread sometimes.
I’ll try to remember that next time and don’t assume you are distracting on purpose 😉
Most scientists attribute the nearly 4 decades of an increasing trend in Southern Hemisphere sea ice to the cooling sea surface temperatures in the Southern Ocean.
Fan et al., 2014
“Cooling is evident over most of the Southern Ocean in all seasons and the annual mean, with magnitudes approximately 0.2–0.4°C per decade or 0.7–1.3°C over the 33 year period [1979-2011].”
—
Gouretski et al., 2012
“[A] rather abrupt cooling since the end of 1990s both in the East Pacific (connected to the weakening of El Nino and the shift to the negative phase of the Pacific Decadal Oscillation) and in the Southern Ocean [see also Knight et al., 2009] may have contributed to a flattening of the global temperature anomaly series after about 2000.”
Of course there is “some effect” from a change in temperature, whether warming or cooling. The cooling of the Southern Ocean has led to increases in sea ice extent, which is in violation of nearly all climate models.
If CO2 is the main cause of shifts in Antarctic sea ice and ice sheet behavior, as you presumably believe, why is it that (a) Antarctica hasn’t warmed to any significant degree since human CO2 emissions began rising rapidly in the 1950s, and (b) why was Western Antarctica and the Peninsula so much warmer than now during the MWP, when CO2 levels were so much lower?
This was the question I asked you that you failed to answer because you thought it was a distraction to talk about temperature as it relates to ice shelf fissures…even though you responded to a comment about the Larsen C breakoff having “nothing to do with temperature” by saying the mechanism is very much related to temperature (warming). And, of course, you still have refused to answer this cogent, on-topic question. I understand why, of course.
You are WRONG as always, seb-t.
The Larson shelf has been there of a long time.. There was nothing “pushing” from behind.
The break is purely the action of its own weight and the cantilever effect PULLING the ice apart at the surface, and the crack eventually letting the berg loose.
You would have to be TOTALLY IGNORANT in basic mechanics not to see this fact.
Your CONTINUED DELIBERATE IGNORANCE in the face of massive SCIENTIFIC proof from K, is just what we have come to expect of you.
It is tantamount to DELIBERATELY DISHONESTY and is the mark of a low-life troll, who’s only intent is to distract others from serious, rational discussion.
Every post from you points out the fact that you are here for ONE purpose and one purpose only…
… being a LOW-LIFE TROLL.
Can you clarify that, please?
On New Zealand television news we had an interview with the glaciologists who had been observing for 16 years the crack which completed recently and allowed a piece of an ice shelf to float away. It was not an iceberg calving off a glacier. They were careful to point out that the glaciers on land would not accelerate into the sea as the ice shelf was not connected to them. So this time the text book example of the glacier speeding up when a large piece breaks up did not apply, they said.
I’m sure you will realise that reality is often not at all like textbook illustrations or demonstrations.
Correct. WWII planes that emergency-landed on Greenland in the early 1940s were found 46 years later in the late 1980s buried under 260 feet of ice.
http://www.nytimes.com/1988/08/04/us/world-war-ii-planes-found-in-greenland-in-ice-260-feet-deep.html
“Given that Antarctica contains enough ice to raise sea levels about 220 feet … the break-up for Larsen C is certainly a big deal.”
Non Sequitur
(also known as: derailment, “that does not follow”, irrelevant reason, invalid inference, non-support, argument by scenario [form of], false premise [form of], questionable premise [form of], non-sequitur)
Description: When the conclusion does not follow from the premises. In more informal reasoning, it can be when what is presented as evidence or reason is irrelevant or adds very little support to the conclusion.
https://www.logicallyfallacious.com/tools/lp/Bo/LogicalFallacies/136/Non-Sequitur
In 1956, and iceberg FIVE TIMES THE SIZE broke off, and it was the second calving that year.
https://realclimatescience.com/wp-content/uploads/2017/07/Image1581_shadow.png
Seems to me that “claimate change” is making smaller chunks break off.
Hint.. Glacier is literally a “river of ice”
What would happen if it didn’t calve occasionally !
[…] New Paper Indicates Subantarctic Glacier Retreat More Extensive In 1700s Than Now […]
In fact, calving icebergs of this kind, borne by ocean currents, will help cooling the oceans a little.