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wili

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Holy Sh!t: Year-Round Arctic BOE Imminent
« on: August 30, 2018, 10:05:30 PM »
OK, I went for the dramatic title!  ;D

Replace "imminent" with "could happen at any time" if you wish...

And add 'nearly' before year-round...but it's still a stunning finding.

But  I don't think the very important "Archived Heat" study that just came out has gotten the attention it deserves here yet.

https://phys.org/news/2018-08-archived-deep-arctic-interior.html

The crucial bit is here:

Presently this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year.

We've had a lot of discussions about when a BOE could occur, but not too many people have argued that we could see it last the full year starting...any time, basically, given the right conditions.

Basically as I understand it, the (relatively) super-heated surface waters warmed by endless summer sun have sunk (due to increased salinity from evaporation) and migrated under the ice pack. Now that hot, salty water is just 'waiting' for a new GAC or something similar to churn it up toward the surface and melt all the ice it comes into contact with, and keep it melted nearly throughout the year.

Robertscribbler has a video on it here: https://robertscribbler.com/2018/08/29/heat-building-beneath-the-sea-ice-hints-at-tipping-points/#comment-148812

I'm gobsmacked, personally. Would love to hear others' reactions.

Here's the link to the original study: advances.sciencemag.org/content/4/8/eaat6773

 "Warming of the interior Arctic Ocean linked to sea ice losses at the basin margins" Science Advances (2018)
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Dharma Rupa

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #1 on: August 30, 2018, 10:20:41 PM »
I think I will wait and see.  I won't deny that BOE could happen at any time, but I do deny that anyone knows when.

bbr2314

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #2 on: August 30, 2018, 10:25:55 PM »
I think it will come about very soon. As 2018 has shown, we are now entering "snowball continents" territory, particularly across North America. When we reach a point where continental extent is greater than sea ice extent, which is most likely to happen in September or October (of what year, we do not know just yet), the inertia of cold continents is (IMO) likely to advect the latent oceanic heat anomalies deeper than ever before into the High Arctic. Simultaneously, a BOE in the CAB will allow prolific snowfalls across the continents due to +++available moisture.

GoSouthYoungins

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #3 on: August 30, 2018, 10:37:31 PM »
I think that it could happen any year now. Next year wouldn't surprise me. Longer than a decade without many months of effectively ice free arctic WOULD surprise me.

If 2019 is an outlier like 2007 or 2012, the arctic goes KABOOM. Since 2007 there has been lots of open water, able to soak up heat, and apparently it is hanging out in the arctic ocean beneath a lighter/less-salty layer.  If there is serious mixing, humpy dumpy will fall off the wall and will not be able to be put back together again.

The very hot Laptev is worrying. The Atlantic ice edge, hundreds of kilometers north of Svalbard/FJL/Severnaya Zemlya is worrying. The unfreezable Bering is worrying. NO old, thick ice is worrying.  And now, we learn that there is heat under the ice pack....VERY WORRYING.

EDIT: This is boring...somebody needs to post that it obviously wont happen for centuries, cuz da models!
big time oops

bbr2314

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #4 on: August 30, 2018, 10:40:28 PM »
It should also be noted that simultaneous to this year's worst-ever ATL front has been the ridiculously resilient CAA.

As the CAB goes BO, we will see the halocline confined to the peripherals, particularly the CAA. BOE doesn't mean ENTIRELY ice free Arctic, it means a reversal of the current state, where the periphery melts prior to the center.

When you flip the equation, you end up with a heat engine that is actually much more robust (as in, despite +GHG, the distribution of heat into space actually increases, leaving temps the same / only slightly higher or lower than today). When this occurs, ultimately the CAB will freeze over again after a decade or two, but by then, the continents above 40N will be iced over and oceanic heat will be depleted.

AbruptSLR

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #5 on: August 30, 2018, 10:51:19 PM »
Note that the warm deep 'archived' water is capped by a cool-fresh layer of water, and the first article indicates that ice mass loss from Greenland has been contributing to feedback mechanisms that has caused the Beaufort Gyre to progressively stockpile more freshwater than all of the great lakes combined (see the first image).  While some consensus scientists will undoubtable emphasize that an eventual release of this freshwater in coming years will result in a temporary cooling of the North Atlantic and Europe, which may decrease GMSTA; I note that such a release of freshwater from the Beaufort Gyre would also slow down the MOC; which in turn would increase climate sensitivity:

Title: "How a Wayward Arctic Current Could Cool the Climate in Europe"

http://e360.yale.edu/features/how-a-wayward-arctic-current-could-cool-the-climate-in-europe

Extract: "The Beaufort Gyre, a key Arctic Ocean current, is acting strangely. Scientists say it may be on the verge of discharging a huge amount of ice and cold freshwater that could kick off a period of lower temperatures in northern Europe.

…something is amiss with this vital plumbing system in the Arctic, a region warming faster than any other on the planet. Thanks in part to rising air temperatures, steadily disappearing sea ice, and the annual melting of 270 billion tons of ice from Greenland’s ice cap, the gyre is no longer functioning as it has predictably done for more than a half century. And now, scientists are anticipating that a sudden change in the Beaufort Gyre could set in motion events that — in a steadily warming world — would actually lead to a temporary but significant cooling of the North Atlantic region.

During the second half of the 20th century — and, most likely, earlier — the gyre adhered to a cyclical pattern in which it would shift gears every five to seven years and temporarily spin in a counter-clockwise direction, expelling ice and freshwater into the eastern Arctic Ocean and the North Atlantic. But for more than a dozen years, this carousel of ice and, increasingly, freshwater has been spinning faster in its usual clockwise direction, all the while collecting more and more freshwater from three sources: melting sea ice, huge volumes of runoff flowing into the Arctic Ocean from Russian and North American rivers, and the relatively fresh water streaming in from the Bering Sea….

The gyre’s strange behavior is likely linked, at least in part, to the profound warming of the Arctic, and it demonstrates how disruptions in one rapidly changing region of the world can affect ecosystems hundreds, even thousands, of miles away. In a recent paper, Krishfield, Proshutinsky, and other scientists suggest that frigid freshwater pouring into the north Atlantic Ocean from the rapidly melting Greenland ice sheet is forming a cap on the North Atlantic that results in stratification that prevents storm-triggering heat from the northern end of the Gulf Stream from rising to the surface. The scientists say this may be inhibiting the formation of cyclones that would cause the motion of the gyre to weaken or temporarily reverse.

If that is the case, it may mean the gyre will continue to grow and spin clockwise for years to come."

See also:

Andrey Proshutinsky, Dmitry Dukhovskoy, Mary-Louise Timmermans, Richard Krishfield, Jonathan L. Bamber (2015), "Arctic circulation regimes", Philosophical Transactions of the Royal Society A, DOI: 10.1098/rsta.2014.0160

http://rsta.royalsocietypublishing.org/content/373/2052/20140160

Abstract: "Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability."

&

The third linked Marino & Zahn (2015) reference (and second attached image) shows how a cooling of the North Atlantic can cause warming around Antarctica and an increase of Agulhas Leakage which can interact with the AMOC to strengthen Arctic Amplification and the bipolar seesaw:

Gianluca Marino and Rainer Zahn (January 2015), "The Agulhas Leakage: the missing link in the interhemispheric climate seesaw?", Past Global Changes Magazine, SCIENCE HIGHLIGHTS: Glacial terminations and interglacials

http://www.pages-igbp.org/download/docs/magazine/2015-1/PAGESmagazine_2015(1)_22-23_Marino.pdf

&

With continued global warming one can expect more Agulhas leakage (see the third image); which per the fourth linked reference means that one can expect the AMOC to continue slowing; which should work synergistically with Hansen's ice-climate feedback, particularly if the WAIS collapses in coming decades:

Kathryn A. Kelly, Kyla Drushka, LuAnne Thompson, Dewi Le Bars & Elaine L. McDonagh (25 July 2016), "Impact of slowdown of Atlantic overturning circulation on heat and freshwater transports", Geophysical Research Letters, DOI: 10.1002/2016GL069789

http://onlinelibrary.wiley.com/doi/10.1002/2016GL069789/abstract

&

The fifth linked reference about the influence of the recent increased Agulhas leakage on tropical Atlantic warming and the response of the AMOC:

Joke F. Lübbecke, Jonathan V. Durgadoo, and Arne Biastoch (2015), "Contribution of increased Agulhas leakage to tropical Atlantic warming", Journal of Climate, doi: http://dx.doi.org/10.1175/JCLI-D-15-0258.1


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0258.1

&

The sixth linked reference (with a free access pdf) indicates that the leakage of warm saline water from the Agulhas Current into the Atlantic Ocean, caused a positive feedback mechanism contributing to polar amplification during the Eemian; and that this mechanism could become increasingly important with increasing global warming today:

Turney, C. S.M. and Jones, R. T. (2010), Does the Agulhas Current amplify global temperatures during super-interglacials?. J. Quaternary Sci., 25: 839–843. doi: 10.1002/jqs.1423

http://onlinelibrary.wiley.com/doi/10.1002/jqs.1423/full
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GoSouthYoungins

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #6 on: August 30, 2018, 11:07:02 PM »
It should also be noted that simultaneous to this year's worst-ever ATL front has been the ridiculously resilient CAA.


When this occurs, ultimately the CAB will freeze over again after a decade or two, but by then, the continents above 40N will be iced over and oceanic heat will be depleted.

The CAA is not all frozen with meters of thick ice. It is simply not abnormally bad.


This is highly speculative, and I personally doubt it will turn out like that. The theory does make sense, but it requires many things to happen which are far from locked in.
big time oops

gerontocrat

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #7 on: August 30, 2018, 11:09:32 PM »
Alarmist nonsense..
If I was one of the authors of this study I would be seriously hacked off.

The Study did NOT say this...
Quote
this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year.

Below I quote the discussion part of the study. There are two threads in that discussion (it seems to me)..

Heat will continue to accumulate at depth especially with more open water in the Chukchi during the high insolation period in summer As a result, there will be more heat coming up all year round, reducing winter ice growth. The study does not suggest a sudden event when 30 years worth of accumulated heat suddenly burps to the surface and poof, no ice. (See the last sentence in the extract below).

If surface water temperature in the Chukchi reaches, say, 13 celsius, the density of this salty water will drop and subduction under the cooler fresher water would stop.

It adds to my and others speculation that it is winter sea ice that is going to be strongly reduced as in the last 2 years. But if subduction stops, the study is silent on this?

_____________________________________________________________
EXTRACT FROM THE STUDY
DISCUSSION
Implications and outlook

The doubling of BG halocline heat content over the past three decades
appears attributable to a warming of the source waters that ventilate the
layer, where this warming is due to sea ice losses in the Chukchi Sea that
leave the surface ocean more exposed to incoming solar radiation in
summer. The effects of an efficient local ice-albedo feedback are thus
not confined to the surface ocean/sea ice heat budget but, in addition,
lead to increased heat accumulation in the ocean interior that has
consequences far beyond the summer season. Strong stratification and weak mechanical mixing in the BG halocline ensure that significant
summertime heat remains in the halocline through the winter.

With continued sea ice losses in the Chukchi Sea, additional heat may continue to be archived in the warm halocline. This underscores the far-reaching implications of changes to the dynamical ice-ocean system in the Chukchi Sea region.

However, there is a limit to this: Once the source waters for the halocline become warm enough that their buoyancy is affected, ventilation can be shut off. Efficient summertime subduction relies on the lateral surface front in the NCS region between warm, salty water that is denser to the south and cooler, fresher water that is less dense to the north. For longer-duration solar warming (that is, longer-duration ice-free conditions in the region), SSTs on the south side of the front may become warm enough (around 13°C, under the assumption of a 1.5-month ice-free period dominated by solar absorption) that the lateral density gradient is eliminated.

It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics of the Arctic halocline. In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.
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bbr2314

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #8 on: August 31, 2018, 12:46:39 AM »
It should also be noted that simultaneous to this year's worst-ever ATL front has been the ridiculously resilient CAA.


When this occurs, ultimately the CAB will freeze over again after a decade or two, but by then, the continents above 40N will be iced over and oceanic heat will be depleted.

The CAA is not all frozen with meters of thick ice. It is simply not abnormally bad.


This is highly speculative, and I personally doubt it will turn out like that. The theory does make sense, but it requires many things to happen which are far from locked in.
It is not all frozen with meters of thick ice, but it is above any year since the 1980s, looking at the data posted elsewhere. Fairly incredible, IMO. Probably also due to the Beaufort Gyre rejecting its FW cap through the CAA this summer?

https://forum.arctic-sea-ice.net/index.php/topic,2223.msg170360.html#msg170360

wili

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #9 on: August 31, 2018, 12:53:13 AM »
Thanks all for a good discussion so far.

Ger said, "If I was one of the authors of this study..."

Well, here is what the lead author of the study had to say:

Quote
"We document a striking ocean warming in one of the main basins of the interior Arctic Ocean, the Canadian Basin," said lead author Mary-Louise Timmermans, a professor of geology and geophysics at Yale University....

"This means the effects of sea-ice loss are not limited to the ice-free regions themselves, but also lead to increased heat accumulation in the interior of the Arctic Ocean that can have climate effects well beyond the summer season," Timmermans said.

"Presently this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year."

Read more at: https://phys.org/news/2018-08-archived-deep-arctic-interior.html#jCp

(I will also point out that there are parallel conversations of this going on in the melt thread, the ice apocalypse thread, and the what's new thread. I dunno if these should be merged, or if it's ok to just have four discussion about the same paper going on in four threads. Mods, whadayathink?)
« Last Edit: August 31, 2018, 01:50:48 AM by wili »
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AbruptSLR

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #10 on: August 31, 2018, 01:00:16 AM »
Alarmist nonsense..
If I was one of the authors of this study I would be seriously hacked off.

The Study did NOT say this...
Quote
this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year.

Below I quote the discussion part of the study. There are two threads in that discussion (it seems to me)..

Heat will continue to accumulate at depth especially with more open water in the Chukchi during the high insolation period in summer As a result, there will be more heat coming up all year round, reducing winter ice growth. The study does not suggest a sudden event when 30 years worth of accumulated heat suddenly burps to the surface and poof, no ice. (See the last sentence in the extract below).


The one consideration that you are ignoring is that per the research that I reference in Reply #5, the relatively freshwater layer immediately above the deeper warm layer of water, is unstable.  So it is not that the deeper and denser warm water will magically float up through less dense cooler water, but rather that the upper cooler/fresher lay may well some day flow laterally away (into the North Atlantic) which would then leave the warm water closer to the surface.
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wili

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #11 on: August 31, 2018, 01:09:30 AM »
I have another question. If all this extra heat is accumulating at depth in the interior of the Arctic, won't some of that heat make its way up to the surface over the winter, even if the heavier salty water itself doesn't? Could this be contributing to thinner ice over the winter, with some bottom melt happening? Has any such extra warming of the sub-ice water been detected?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

FishOutofWater

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #12 on: August 31, 2018, 01:16:26 AM »
One thing I know for sure about that article which I discussed over in the melting season thread is that it does not say or imply in any way that an Arctic blue ocean event is imminent. As has often been the case in the past, Robert lacks the scientific background to analyze a research report accurately. He's a skilled writer but he makes many mistakes in scientific interpretation.

If there is a BOE it won't be caused by the modest heat build up in the Beaufort sea from the Chukchi summer water injection. It will be from "Atlantification" of the Arctic.

wili

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #13 on: August 31, 2018, 01:21:18 AM »
FOOW, thanks for that perspective, and for the section of the article you quoted in the melting season thread that pretty well answers the question I posed, so I'll copy it again here:

Quote
While vertical heat fluxes from the warm halocline are inhibited by the halocline stratification (that is, diapycnal diffusion is weak), reasonable estimates for heat lost vertically from the warm halocline may be obtained by considering the range of turbulent diffusivities estimated from observations in the central Canada Basin halocline: ~10−7 to 10−6 m2 s−1 (20). Heat loss is only considered across the top boundary of the layer. The range of diffusivities acting on the vertical temperature gradient centered around S = 31 (the top of the warm halocline) gives rise to upward heat fluxes in the range of 0.03 to 0.3 W m−2.

 Taking the heat content in the layer to be ~4 × 108 J m−2, these fluxes suggest a time scale for diffusive removal of the anomalous layer heat of between 40 and 400 years.

 Therefore, we cannot rule out that some fraction of the subducted summer heat is lost from the layer by vertical diffusion. Note that eddy fluxes may also be responsible for transporting heat laterally out of the BG region in a dynamical response to the wind-energy input

What do you make of the statement from the lead author:

"Presently this heat is trapped below the surface layer. Should it be mixed up to the surface, there is enough heat to entirely melt the sea-ice pack that covers this region for most of the year."

Is that merely meant to be a hypothetical to indicate how much extra heat we're talking about?

I do appreciate your point about Atlantification. It looks to me, though, as if ASI is being attacked from two (or more?) fronts. But certainly right now the Atlantic side is much more dramatic and visible.

I would also like to point to the last paragraph of the section of the paper that ger so kindly copied for us:

Quote
It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics of the Arctic halocline.

In other words, though they don't know exactly how or when, they expect the layer structure to go through some kind of major "fundamental" change. What else could that mean except that they think the lower, saltier layer will not remain below. So there's that.

Quote
In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

So even before the current layered structure of the Arctic has undergone the expected 'fundamental change,' the effects of this heat will be felt very soon, not decades or centuries, but in 'coming years.'

Am I misinterpreting something here? I do admit that given prevailing scientific reticence, it's kind of the rest of our job to try to re-state the bland academic language in something closer to what average people can understand and in a tone that reflects the importance of the information, while keeping as true as possible to the basic facts being presented.

Thanks one and all for help in digesting this important study.
« Last Edit: August 31, 2018, 01:46:39 AM by wili »
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Rod

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #14 on: August 31, 2018, 01:57:45 AM »
wili - Assuming Professor Timmermans was accurately quoted in the news article, she limited her statement to "the sea ice pack that covers this region."

The paper looked at 30 years of data from the Beaufort Gyre region.  I can't quote the paper because I'm on my phone, but look at the last full sentence in the second full paragraph in the introduction.  The authors are clear about the data they are using. 

Saying there is enough heat trapped below the surface layer to melt the sea ice pack in "this region [the Beaufort Gyre]" is very different than saying a blue ocean event for the entire arctic is imminent.   

Dharma Rupa

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #15 on: August 31, 2018, 02:10:10 AM »
The one consideration that you are ignoring is that per the research that I reference in Reply #5, the relatively freshwater layer immediately above the deeper warm layer of water, is unstable.  So it is not that the deeper and denser warm water will magically float up through less dense cooler water, but rather that the upper cooler/fresher lay may well some day flow laterally away (into the North Atlantic) which would then leave the warm water closer to the surface.

One thing I have wondered about is that if enough of the fresh water lens is removed first would it be possible for the rest of the fresh water to simply freeze?  Can the halocline collapse due to the onset of Winter some year?

FishOutofWater

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #16 on: August 31, 2018, 02:53:07 AM »
This summer the fresh water has poured into the Arctic from Siberian rivers at an above average rate because of last winter's heavy Siberian snow pack. The fresh water layer is restored to some extent every summer when warm fresh light water flows in from Siberian rivers. However, at some point in the future climate warming and ice loss may cause more ocean mixing as Siberia cools in the fall while storms rack the Siberian seas.

Wherestheice

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #17 on: August 31, 2018, 04:35:07 AM »
All i know is the BOE is coming soon. Many factors contribute, but most here know that
"When the ice goes..... F***

Rod

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #18 on: August 31, 2018, 05:08:01 AM »
All i know is the BOE is coming soon. Many factors contribute, but most here know that

I won't quibble with this.  All you need to do is look at worldview today.  There is an usually large area of clear skies close to the North Pole and the ice looks terrible. 

As many people on this forum have noted, this melting season has been really bad for the future of the ice.  There is no way to know when the first BOE will occur, but there are many factors that continue to move us in that direction. 

However, I don't think it is helpful to take a very good research paper and claim that it reports findings that it clearly does not. 

I understand some of the confusion likely arose from the news articles quoting the lead author.  But, even the quote does not in any way support the title of this thread. 
« Last Edit: August 31, 2018, 05:17:33 AM by Rod »

wili

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #19 on: August 31, 2018, 05:37:52 AM »
Rod said: "there is enough heat trapped below the surface layer to melt the sea ice pack in "this region [the Beaufort Gyre]" "

Thanks, that makes sense. I had assumed that 'region' meant the whole of the Arctic, but in the context of the rest of the study, you're probably right that she just meant the BG.

But that is a pretty big area.

And combined with what FOOW is saying about Atlantification, that would indeed mean the end of most ice throughout the Arctic, wouldn't it?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

miki

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #20 on: August 31, 2018, 05:51:40 AM »
Rod said: "there is enough heat trapped below the surface layer to melt the sea ice pack in "this region [the Beaufort Gyre]" "

Thanks, that makes sense. I had assumed that 'region' meant the whole of the Arctic, but in the context of the rest of the study, you're probably right that she just meant the BG.

But that is a pretty big area.

And combined with what FOOW is saying about Atlantification, that would indeed mean the end of most ice throughout the Arctic, wouldn't it?

Indeed.

Rod

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #21 on: August 31, 2018, 06:00:50 AM »
I would add that it could eventually, but a lot needs to happen to get us there.

First, you need a mechanism to get all the heat that is currently at 50m and lower up to the surface.  That would require a breakdown of halocline.  The changing arctic seas might be leading us in that direction, but there is no evidence I have seen indicating that it is happening now. 

I agree completely with Fish on the importance of Atlantification on the other side of the CAB.  I think we have seen strong evidence this year that it is progressing much faster than the models predicted.   But again, there is no current evidence I have seen that would demonstrate we are on the verge of collapse.   

The ice is in bad shape, but a lot still needs to happen before we see a BOE, and a whole lot more would need to happen before it would be year round! 

Things are changing fast in the arctic.  I would not want to venture a guess on when the first BOE will be.  I don't disagree it could be soon, but I seriously doubt that it is "imminent." 

Wherestheice

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #22 on: August 31, 2018, 06:11:26 AM »
I would add that it could eventually, but a lot needs to happen to get us there.

First, you need a mechanism to get all the heat that is currently at 50m and lower up to the surface.  That would require a breakdown of halocline.  The changing arctic seas might be leading us in that direction, but there is no evidence I have seen indicating that it is happening now. 

I agree completely with Fish on the importance of Atlantification on the other side of the CAB.  I think we have seen strong evidence this year that it is progressing much faster than the models predicted.   But again, there is no current evidence I have seen that would demonstrate we are on the verge of collapse.   

The ice is in bad shape, but a lot still needs to happen before we see a BOE, and a whole lot more would need to happen before it would be year round! 

Things are changing fast in the arctic.  I would not want to venture a guess on when the first BOE will be.  I don't disagree it could be soon, but I seriously doubt that it is "imminent."

I also don't think it will be imminent or (about to happen), but based off trends in volume alone. It is very possible in the next handfull of years. If we get the right weather and a bad refreeze before hand.... Definitely possible!
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johnm33

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #23 on: August 31, 2018, 10:59:22 AM »
If we lose the freshwater lens we should see increased sea levels on Americas east coast, that water is relatively inert and will be hard pressed along the coast all the way to the Carolinas. Then we have to watch highs and lows entering the Arctic and moving across the bathymetry generating internal waves stirring the deep. Whilst it looks too late this season for a BOE the ice certainly looks too weak to suppress wave action. Pity there's not an ice opening gif on Hycom that covers the whole arctic.

gerontocrat

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #24 on: August 31, 2018, 11:26:39 AM »
I have another question. If all this extra heat is accumulating at depth in the interior of the Arctic, won't some of that heat make its way up to the surface over the winter, even if the heavier salty water itself doesn't? Could this be contributing to thinner ice over the winter, with some bottom melt happening? Has any such extra warming of the sub-ice water been detected?

That is exactly what the study says...
Quote
In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

Herewith a table of winter max km2 and max vol in km3 for the last few years for the total Arctic. Finding data for just that part of the Arctic considered by the study might be difficult to impossible.

Year   Jaxa Extent Km2   Piomas Volume Km3 '000
2012    14,709,086    23.365
2013    14,523,635    23.332
2014    14,448,416    23.118
2015    13,942,060    24.394
2016    13,942,507    22.715
2017    13,878,287    20.782
2018    13,891,190    22.380

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crandles

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #25 on: August 31, 2018, 01:43:33 PM »

Quote
In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

So even before the current layered structure of the Arctic has undergone the expected 'fundamental change,' the effects of this heat will be felt very soon, not decades or centuries, but in 'coming years.'

Am I misinterpreting something here?

What proportion of folks thinks this is new and/or only in 'coming years' as opposed to thinking this has contributed to upward heat flux over the last few years (or decades) and therefore already included in the trend of observations?

Just because this is being talked about in this way for the first time doesn't mean it hasn't been there in the observations.

Shared Humanity

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #26 on: August 31, 2018, 01:56:15 PM »

Quote
In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

So even before the current layered structure of the Arctic has undergone the expected 'fundamental change,' the effects of this heat will be felt very soon, not decades or centuries, but in 'coming years.'

Am I misinterpreting something here?

What proportion of folks thinks this is new and/or only in 'coming years' as opposed to thinking this has contributed to upward heat flux over the last few years (or decades) and therefore already included in the trend of observations?

Just because this is being talked about in this way for the first time doesn't mean it hasn't been there in the observations.

It is absolutely already coming into play. It is not as if there is an on/off switch. This is a process of transitioning from the stable Arctic we knew to something completely different.

There is more open water, soaking up sunlight.
There is more ocean heat at depth.
There are increasingly stormy open seas with waves as high as 6 meters, mixing surface waters.

(Feel free to add your own items to this list.)

All of this is already eating at the ice, slowing freeze and accelerating melt. We have been watching a fascinating event unfold north of Greenland this year. Could ocean heat at depth, upwelling along the CAA and coast of Greenland, be contributing to this?

FishOutofWater

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #27 on: August 31, 2018, 02:22:44 PM »
The specific process discussed in the recent paper has had a minimal impact on the sea ice heat budget and thickness so far. Heat has been building up in the halocline and only in the last few years has it reached the continental shelf margins where some of it might be welled up by Ekman divergence.

There's been a massive amount of heat added to the north Atlantic by GHG driven global warming and that heat has pushed into the Barents sea increasing the ice free area in the far north. Atlantic water has heated the north shores of western Siberia and some heat is being subducted to the 1000m layer. I don't have numerical values at my fingertips but I'm sure that the heat content added on the Atlantic side of the Arctic is much larger than the heat added by subduction of Chukchi sea summer water.

Here's an article I just looked at about the "Great Salinity Anomaly" which was apparently caused by a jump in transport of sea ice and fresh water out of the Arctic through the Fram strait in the late 1960s and early 1970s. This fresh water pulse evidently caused a brief cooling of the whole northern hemisphere by slowing down the AMOC. Right now, Fram strait transport is at a minimum so don't expect that to be repeated any time soon.

https://epic.awi.de/31231/1/InTech-Causes_and_consequences_of_the_late_1960s_great_salinity_anomaly.pdf


Richard Rathbone

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #28 on: August 31, 2018, 02:34:56 PM »

Quote
In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.

So even before the current layered structure of the Arctic has undergone the expected 'fundamental change,' the effects of this heat will be felt very soon, not decades or centuries, but in 'coming years.'

Am I misinterpreting something here?

What proportion of folks thinks this is new and/or only in 'coming years' as opposed to thinking this has contributed to upward heat flux over the last few years (or decades) and therefore already included in the trend of observations?

Just because this is being talked about in this way for the first time doesn't mean it hasn't been there in the observations.

There was about 0.2m of avoided winter growth in the 2000s from heat pumped down in summer coming back up in winter. I haven't seen a more recent calculation but its been going on a long time already.

GoSouthYoungins

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #29 on: August 31, 2018, 03:02:07 PM »
There is more open water, soaking up sunlight.
There is more ocean heat at depth.
There are increasingly stormy open seas with waves as high as 6 meters, mixing surface waters.

(Feel free to add your own items to this list.)

All of this is already eating at the ice, slowing freeze and accelerating melt. We have been watching a fascinating event unfold north of Greenland this year. Could ocean heat at depth, upwelling along the CAA and coast of Greenland, be contributing to this?

There is more open water, soaking up sunlight.
There is more ocean heat at depth.
There are increasingly stormy open seas with waves as high as 6 meters, mixing surface waters.
There is a warmer atmosphere, particularly in winter.

(Feel free to add your own items to this list.)

I believe heat from below is the only explanation for the melting in the Lincoln Sea. It was been shown quite well on this forum that it was not only drift, but genuine melt occurring. And there was not the sunshine or air temps necessary for melts, so ocean heat rising appears the sole candidate. Scary stuff.
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binntho

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #30 on: August 31, 2018, 03:57:20 PM »
It somehow seems logical that the heat from below will rise, even without mixing. But then again, mixing (waves or Ekman pumping or what have you) will certainly allow heat to rise much faster.

But the deep "archive" of ever warmer waters is not insulated from the upper, colder, layers - so an increase in deep heat must affect the ice.
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FishOutofWater

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #31 on: August 31, 2018, 04:41:45 PM »
Without dynamic mixing such as Ekman divergence, eddies, waves and tidal interactions with continental shelves heat flow from subsurface layers is quite slow. The paper estimates times of 40 to 400 years for heat to diffuse into the upper layer. However, rates along continental margins are much faster because Ekman divergence, tides and eddies all increase mixing.

AbruptSLR

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #32 on: August 31, 2018, 05:08:32 PM »
What proportion of folks thinks this is new and/or only in 'coming years' as opposed to thinking this has contributed to upward heat flux over the last few years (or decades) and therefore already included in the trend of observations?

Just because this is being talked about in this way for the first time doesn't mean it hasn't been there in the observations.

It is pleasant to assume that the Beaufort Gyre has been behaving normally for the past decades, but measurements present a different picture:

Title: "How a Wayward Arctic Current Could Cool the Climate in Europe"

http://e360.yale.edu/features/how-a-wayward-arctic-current-could-cool-the-climate-in-europe

Extract: "The Beaufort Gyre, a key Arctic Ocean current, is acting strangely. Scientists say it may be on the verge of discharging a huge amount of ice and cold freshwater ...
...
The gyre’s strange behavior is likely linked, at least in part, to the profound warming of the Arctic, and it demonstrates how disruptions in one rapidly changing region of the world can affect ecosystems hundreds, even thousands, of miles away. In a recent paper, Krishfield, Proshutinsky, and other scientists suggest that frigid freshwater pouring into the north Atlantic Ocean from the rapidly melting Greenland ice sheet is forming a cap on the North Atlantic that results in stratification that prevents storm-triggering heat from the northern end of the Gulf Stream from rising to the surface. The scientists say this may be inhibiting the formation of cyclones that would cause the motion of the gyre to weaken or temporarily reverse.

If that is the case, it may mean the gyre will continue to grow and spin clockwise for years to come.""
« Last Edit: August 31, 2018, 05:14:21 PM by AbruptSLR »
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bluesky

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #33 on: August 31, 2018, 07:18:34 PM »
Would it be possible that the extreme melt in 2012 was enhanced by the GAC churning up some of this warm halocline layer in Beaufort sea, and spreading it to the surface and more widely? Maybe it would be interesting to get the March and September 2012 vertical temperature and salinity in Beaufort and other part of the Arctic sea? What about the possibility of heat accumulation in other part e.g. Laptev sea and North Kara/Barents seas heat accumulation creating a warm halocline in Nansen/ Fram basin, the same for ESS and Makarov basin, let alone "atlantification"?

Niall Dollard

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #34 on: August 31, 2018, 07:58:01 PM »
I believe heat from below is the only explanation for the melting in the Lincoln Sea. It was been shown quite well on this forum that it was not only drift, but genuine melt occurring. And there was not the sunshine or air temps necessary for melts, so ocean heat rising appears the sole candidate.

Not the only explanation. The NSIDC's recent comment on this region:
"The region normally consists of thick, consolidated ice from a general pattern of on-shore ice motion. Even when winds blow offshore, the strength of the thick ice would hold in place along the coast. However, current ice conditions appear more broken up and likely thinner, and over the past couple of weeks, offshore winds have succeeded in pushing ice off of the coast."

A combination of lack of multi year ice (thinner ice) combined with high temperatures and offshore southerly winds sounds plausible to me.

The ice began to move around the 4th of August, when winds turned to a SSW direction at Alert. Then followed several days of southerly winds and temps over 15 C.  It wasn't until the 12th before the winds swung around the north.

Perhaps with more multi year ice the pack could survive such a strong week-long attack like this in August But clearly not this year.   

In the period 18th July to 20th August Alert had 12 days with max above 10C.

wili

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #35 on: August 31, 2018, 09:00:56 PM »
Bluesky wrote: "Would it be possible that the extreme melt in 2012 was enhanced by the GAC churning up some of this warm halocline layer in Beaufort sea, and spreading it to the surface and more widely?"

I wondered about that at the time. There were still big enough chunks of ice/icebergs around that a high level of wind pushing a little on the top would make a largish stir at the base, possibly bringing up some of the salty, warm water from below. I've never heard anyone else (besides you now) even speculate on it, that I recall.
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Dharma Rupa

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #36 on: August 31, 2018, 09:56:26 PM »
Looking at the title of this thread...I don't know about it being imminent, however, I do think that when DMI 80N in Summer is no longer pinned at about 0 degrees then the majority of the CAB will fail to freeze over the following Winter.

I think the biggest single thing will be the failure of the halocline, but I also think it will be a plurality of the causes, not the majority.


jdallen

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #37 on: August 31, 2018, 10:36:53 PM »
OK, first off, there has always been enough heat in the Arctic ocean to melt the ice, and keep it of, even during winter.  What saves the ices is the fact the heat is isolated below thermoclines and haloclines.

What I consider the real take-away of the paper is that it confirms my sense of how the system is changing, and how a BOE will eventually take place.

That enthalpy has doubled does not instantly mean the event is imminent.  This process is more like something out of Poe's "Pit and the Pendulum".

Our swinging blade - "pendulum" is the annual swing in insolation and heat transported into the Arctic.  Each swing varies slightly from the last, but falls predictably within a given envelope which encompasses the observed range annual heat uptake; heat uptake which is reflected in a combination of SST's and ice coverage.  Some years are 2012.  Others are 2013.   But, each year the heat is enough to melt between 16,000 and 20,000+ KM3 of ice.  (it used to be ~15-18, but over the last 20 or so Arctic Amplification has pushed the number up - see Jim Pettit's graphs).

Like Poe's "Pendulum" that swing cuts a little more deeply each swing because of increased available heat, but even with that the process of it finally whittling down the Arctic pack to a BOE will be very slow - like centuries - unless it gets help.

So our heat in the water is the wildcard that will accelerate that.  Unlike Poe's "pit", where the table our victim - the ice - is strapped to is fixed to the floor, the Arctic's is "moveable".  Namely this - that increasing enthalpy effectively raises the surface under the blade, making increasing areas of ice vulnerable to full melt out.  The practical way it performs this is by limiting how much ice can form, and how fast, rather than melting the ice directly.

So far we've seen this play out in the Barents and Greenland seas, neither of which typically fully melted out in the past, but now do.

I think this will become more apparent in the Chukchi and the Bering, and to a lesser degree the Kara.  Eventually it will be apparent in the Laptev, Beaufort and lagging behind those, the ESS.

I think reduced ice creation over time in these seas will eventually, over a much shorter timescale make the entire arctic vulnerable to a BOE happening through completely mundane seasonal variation in captured heat.

I will start expecting it imminently when the winter max volume drops under 20,000KM3.  When we hit that threshold, I think we will have a 1 in 10 chance that year of a BOE with relatively normal melt.  When the max drops below 19,000KM3, I think it will rise to a 1 in 4 chance.  At 18,000KM3 I think it will be 1 in 2.

So that's what I'll be watching for - decreasing end of freeze season volume.

As a last comment, I'll add that increasing ocean heat has a strong self-reinforcing feedback attached to it.  As we lose ice off of the peripheral seas, we will greatly increase heat uptake because of decreased albedo.  There are other factors here which are self-reinforcing, but the key take away is the warmer the water gets, the greater potential exists for increased heat capture.
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Dharma Rupa

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #38 on: August 31, 2018, 11:41:20 PM »
I will start expecting it imminently when the winter max volume drops under 20,000KM3.  When we hit that threshold, I think we will have a 1 in 10 chance that year of a BOE with relatively normal melt.  When the max drops below 19,000KM3, I think it will rise to a 1 in 4 chance.  At 18,000KM3 I think it will be 1 in 2.

Since I am expecting warm Winters and cold Summers I am unable to fully evaluate what you are saying here.

wili

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #39 on: September 01, 2018, 12:51:33 AM »
Nice post, jda.

And here I thought I was being dramatic. Poe makes it much more so!  :)

Perfect "Pit in the Pendulum" metaphor:

"the Arctic's is "moveable".  Namely this - that increasing enthalpy effectively raises the surface under the blade, making increasing areas of ice vulnerable to full melt out. "

I hate to be the one putting it in a less dramatic way, but basically, we know now that the ice is increasingly being attacked from all sides!

And that all those attacks will inevitably be increasing over time (though with the variability in any particular year that you so ably articulate).
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

jdallen

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #40 on: September 01, 2018, 04:26:00 AM »
I will start expecting it imminently when the winter max volume drops under 20,000KM3.  When we hit that threshold, I think we will have a 1 in 10 chance that year of a BOE with relatively normal melt.  When the max drops below 19,000KM3, I think it will rise to a 1 in 4 chance.  At 18,000KM3 I think it will be 1 in 2.

Since I am expecting warm Winters and cold Summers I am unable to fully evaluate what you are saying here.

Pure statistical prediction - let me put one of Jim Pettit's graphs up for reference:

https://sites.google.com/site/pettitclimategraphs/sea-ice-volume#asivamlir

I'm basing my thinking off of year over year fluctuations in volume.  Your "warm winters" factor into this in as much as over the last two decades, the volume regrowth has steadily declined.  I'm thinking our increasing Arctic oceanic enthalpy is a not-insignificant contributor here.

Annual loss has stayed surprisingly flat.  It's only over the last 20 years or so it ticked up - from a range of about 16,000KM3 +/- about 2000 to somewhere around 18,000KM2 +/- 2000KM3.  Two of those most recent years with melt out of 20,000KM3 are actually outliers - 2010 & 2012, so it might be safer to say the loss is closer to 17,000KM3 +/- 2500KM3.

So back to your cold summers.  Even if we presume they stay low - under 17,000KM3 lost during the season, our decreasing end-of-refreeze season volume is on the threshold of entering the envelope within which a serious melt year - like 2010/12 - could push us into a BOE event - which I'm defining as 1000KM3 of remaining ice or less - which at an average 1M thickness would be about 1,000,000KM2 of area.

As that end of season volume continues to trend downwards, the threat increases as a BOE could result from a larger portion the variability in our annual melt season volume loss.

It's pretty wild-assed guesswork at this stage, as the sample we have for season over season melt losses is both small, and the underlying conditions are not static, which makes any kind of deviation probability predictions pretty meaningless.

So, our two values - end of season maximum volume, and annual volume loss - are on intersecting trajectories.  I don't think ice loss is going to change radically.  However, increasing ocean heat and related knock-on positive feedbacks I think will increasingly erode the numbers we see for our annual maximum, and may have been key factors we hadn't previously understood, as until the last couple years, we've been far more focused on what happens in summer.

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Dharma Rupa

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #41 on: September 01, 2018, 02:50:23 PM »
...
So, our two values - end of season maximum volume, and annual volume loss - are on intersecting trajectories.  I don't think ice loss is going to change radically.  However, increasing ocean heat and related knock-on positive feedbacks I think will increasingly erode the numbers we see for our annual maximum, and may have been key factors we hadn't previously understood, as until the last couple years, we've been far more focused on what happens in summer.

Seems reasonable to me.

Klondike Kat

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #42 on: September 01, 2018, 05:47:00 PM »
While the winter maximum has certainly declined in result years, the decline in summer minimum appears to have stalled.  I will reserve my endorsement until the summer minimum begins another descent.

Archimid

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #43 on: September 03, 2018, 02:51:55 AM »
By then it might be too late to do anything about it.
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jdallen

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #44 on: September 03, 2018, 06:04:20 AM »
While the winter maximum has certainly declined in result years, the decline in summer minimum appears to have stalled.  I will reserve my endorsement until the summer minimum begins another descent.
I have to disagree with you here, the decline in summer minimum really hasn't stalled.

Year/ End of Season in KM3 (Numbers c/o Jim Pettit)
   
1997 - 13178
1998 - 11512
1999 - 10916
2000 - 10954
2001 - 12179
2002 - 10792
2003 - 10240
2004 -  9881
2005 -  9159
2006 -  8993
2007 -  6458
2008 -  7072
2009 -  6839
2010 -  4582
2011 -  4302
2012 -  3673
2013 -  5392
2014 -  6812
2015 -  5684
2016 -  4402
2017 -  4539

If you consider this trend in context to year-over-year melt season weather, its definitely trending down.  The 2010-2012 blip up was characterized by melt seasons where 19-20,000 KM3 of ice melted - at the high end of what's typical.  If you look at 2013-2015, those melt years had 1000-2000KM3 less melt, thus the bump back up.

If you look at just the seasonal maximums, the trend down is even more clear.
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Klondike Kat

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #45 on: September 04, 2018, 04:02:57 AM »
While the winter maximum has certainly declined in result years, the decline in summer minimum appears to have stalled.  I will reserve my endorsement until the summer minimum begins another descent.
I have to disagree with you here, the decline in summer minimum really hasn't stalled.

Year/ End of Season in KM3 (Numbers c/o Jim Pettit)
   
1997 - 13178
1998 - 11512
1999 - 10916
2000 - 10954
2001 - 12179
2002 - 10792
2003 - 10240
2004 -  9881
2005 -  9159
2006 -  8993
2007 -  6458
2008 -  7072
2009 -  6839
2010 -  4582
2011 -  4302
2012 -  3673
2013 -  5392
2014 -  6812
2015 -  5684
2016 -  4402
2017 -  4539

If you consider this trend in context to year-over-year melt season weather, its definitely trending down.  The 2010-2012 blip up was characterized by melt seasons where 19-20,000 KM3 of ice melted - at the high end of what's typical.  If you look at 2013-2015, those melt years had 1000-2000KM3 less melt, thus the bump back up.

If you look at just the seasonal maximums, the trend down is even more clear.

Actually your data supports my point.  In your data, the Arctic sea ice minimum was in a slow decline for the the five years, but then accelerated from 2001-2010.  The sea ice minimum declined an average of 741 km3 / year.  Since then, the decline has stalled.  From 2010-2018, the minimum has not declined, but actually increased at a slight rate of 91 km3 / year.  As mentioned previously, I will reserve endorsement until the minimum starts to decline again.

Wherestheice

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #46 on: September 04, 2018, 04:15:56 AM »
While the winter maximum has certainly declined in result years, the decline in summer minimum appears to have stalled.  I will reserve my endorsement until the summer minimum begins another descent.
I have to disagree with you here, the decline in summer minimum really hasn't stalled.

Year/ End of Season in KM3 (Numbers c/o Jim Pettit)
   
1997 - 13178
1998 - 11512
1999 - 10916
2000 - 10954
2001 - 12179
2002 - 10792
2003 - 10240
2004 -  9881
2005 -  9159
2006 -  8993
2007 -  6458
2008 -  7072
2009 -  6839
2010 -  4582
2011 -  4302
2012 -  3673
2013 -  5392
2014 -  6812
2015 -  5684
2016 -  4402
2017 -  4539

If you consider this trend in context to year-over-year melt season weather, its definitely trending down.  The 2010-2012 blip up was characterized by melt seasons where 19-20,000 KM3 of ice melted - at the high end of what's typical.  If you look at 2013-2015, those melt years had 1000-2000KM3 less melt, thus the bump back up.

If you look at just the seasonal maximums, the trend down is even more clear.

Actually your data supports my point.  In your data, the Arctic sea ice minimum was in a slow decline for the the five years, but then accelerated from 2001-2010.  The sea ice minimum declined an average of 741 km3 / year.  Since then, the decline has stalled.  From 2010-2018, the minimum has not declined, but actually increased at a slight rate of 91 km3 / year.  As mentioned previously, I will reserve endorsement until the minimum starts to decline again.

This all seems like pointless chatter to me. The trend is down, the ice is going away. The rate in decline of extent has slowed, but theres less ice. 2012 was the lowest on record, 2016 second lowest. Next year is probably gonna set some new record. Volume and thickness is still the most important factor here. So to me at least it seems like a waste of time to argue about rates in decline of extent.
"When the ice goes..... F***

Human Habitat Index

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #47 on: September 04, 2018, 05:20:20 AM »
The trend is not our friend.
There is a principle which is a bar against all information, which cannot fail to keep a man in everlasting ignorance. That principle is contempt prior to investigation. - Herbert Spencer

Wherestheice

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #48 on: September 04, 2018, 05:37:00 AM »
The trend is not our friend.

Egg xactly. The trend is down, the trend points to an ice free arctic in the summer in the 2020's.
"When the ice goes..... F***

Wherestheice

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Re: Holy Sh!t: Year-Round Arctic BOE Imminent
« Reply #49 on: September 04, 2018, 05:41:39 AM »
We all need to remember that there is a lot of noise in the arctic system. We are marching towards a BOE. Its to hard to tell what year it will be, but it could be any year at this point.
"When the ice goes..... F***