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Messages - Glen Koehler

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1
Arctic sea ice / Re: "Stupid" Questions :o
« on: December 07, 2019, 06:00:04 PM »
Edited quotes
I see that you have all been having a lot of fun debunking my claims. And perhaps they needed debunking, who knows.
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So global warming. Yes, it's a disaster. No, we are not going to stop it. So how much of a disaster is it going to be?
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The only true threat to global civlisation would be a large and consistent disruption in food production. And I'm not seeing anybody predicting such an outcome (although it does seem to me to be at least a possibility).
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Another of the papers he links to makes some properly dystopian claims, e.g. that CO2 "... is rapidly heading towards levels last seen some 50 million years ago — in the Eocene — when temperatures were up to 14 °C higher than they were in pre-industrial times."
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Yes I know that end-of-world prophecies are exciting and lot's of people seem to wish for some sort of apocalypse. I don't
binntho - Disagreement is not opprobrium or personal attack.  You are well known in this forum for providing thoughtful opinion and insight.  If some nut job jumped onto the forum and wrote that disrupting the planetary climate would have minor effect on well being, people would just dismiss it and not bother to respond with forceful argument.  It is exactly because you do seem intelligent, informed, and curious that folks weigh in to redirect what I (and I presume others too) see as a colleague who is engaging in delusional thinking.  We argue with you because we care and trust that you have the ability to change your mind.  That requires the same of us.  I submit that the facts do not support your position. 

RE: "No, we are not going to stop it." 
     It is not a yes/no situation.  Significant damage has already been done.  Dorian/Great Barrier Reef/2003 Eur. heat wave, etc etc ad nauseum.  I personally don't see how there is ANY chance of not breeching 1.5 C, so I wish IPCC would stop paying it lip service.  But we still have the ability to halt the destruction, pain, and loss caused at 2C or 3C vs. 4C.  By numerous analyses by people who dedicate their professional lives to understand this stuff, getting to 4C could result in a runaway situation where human action is overwhelmed by natural reinforcing feedback mechanisms.

RE My #3 citation quoting Lenton et al. Nov. 2019 article in Nature --
     The list of authors for that piece includes many widely recognized top-tier experts (published in the 1st or 2nd most respected peer-reviewed journal).  "Trust the experts" has fallen out of favor now that with the internet anybody can "publish" any thought that bubbles up through their brain (self included). 

     But facts and expertise still matter.  I still trust the experts when I have a toothache or when the relevant experts tell me that the global ecosystem on which I and my children are utterly and entirely dependent is being irrevocably altered.  You misunderstand and misrepresent their statement about potential for a runaway temperature increase.  They did not say that human emissions alone would drive CO2 to 2500ppm.  But there are powerful feedbacks that can and have done exactly that.  That scenario is not merely hypothetical, it has happened before and can happen again.  It is an engineering analysis of physical properties, not a prophecy based on philosophy.  To ignore factual warnings by experts is self-destructive.

     Heeding warnings of impending destruction and attempting to avert it by spreading the alarm is not wishing for it.  The scale of response needed to reinvent and replace our energy system on a global scale is daunting and difficult.  To succeed will require unprecedented concerted action across political, ethnic, economic and other boundaries.  Humanity faces a sink or swim crisis. 

RE:  Not finding scientific evidence for climate change impact on agriculture
     All I can say is look again. It's there.  Lots of it.  Reduced crop yields as cropping areas exceed tolerances for plants already near their thermal maximum.  A CO2 fertilization effect that only allows crop plants more vegetative growth if water, temperature stability and other needs that are threatened by climate change are controlled.  And even if that vegetative growth does occur, it largely acts to dilute food nutrient density instead of increasing it.  As for, "we'll just move cropping areas north with the shifting isotherm", it isn't that simple.  The solar radiation supply required for photosynthesis is not moving north, nor are the soil resources farther north the same as current ag production zones.  Add in altered, and more likely more erratic, precipitation patterns and the prospects for simply shifting north become even more challenging.  As for that CO2 fertilization effect, here is some more bad news -- weeds are better adapted to benefit from it than crops.  Weeds already outpace insect and disease pests for crop production losses.

     There may be localized benefits for a few cool ag production areas where water supply is not reduced.  I happen to live and work in one such area.  But even here the cost-benefit ratio is not necessarily positive.  For the planet overall, the studies show net negative impacts that increase with additional warming.  The result  is stalled or reversed productivity when we need the opposite to feed a larger population.  = Supply-Demand Train wreck.

     Any "ism" taken to an extreme becomes destructive.  Capitalism run amok becomes Nazi fascism.  Socialism run amok becomes Animal Farm Big Brother 1984 totalitarian communism.   Religious isms run amok become the Crusades,the Jonestown massacre, or ISIS.  Maybe Humanism run amok becomes a sterile, isolated, solopsistic, empty narcissism, where the feelings and dignity of other creatures has zero value.  Utlimately that could include other people.  I wonder if the shrinking circle of that logic ends up as Meism.  That seems like the definition of hell.  I prefer a world of other beings that can delight, surprise, and teach me expressly because they are different from me, yet we share a common existence.

     Enough of my self-published internet philosophizing.  To bring it all all back to GDP, we could have a glorious world and a massive economic boon by taking the actions needed to prevent climate catastrophe.   I wish the big business interests would pull their heads out of their asses long enough to see that opportunity.   The money we spend on military budgets would probably be enough to pull it off.

2
Arctic sea ice / Re: "Stupid" Questions :o
« on: December 07, 2019, 12:29:07 AM »
     No, "life on Earth" is not at risk.
The cockroaches love this stuff.  They've seen it before.  Millions of years before the first human walked on two legs. Cockroaches just need some warmth, some organic matter to feed on, and a rock to hide under.  So they will be fine.

     It is this complicated set of brittle, tinker toy supply-chain connections that we call "society" that is vulnerable to catastrophic failure.
     It is the "organized (human) global community" that is at stake, i.e. "civilization".  Things like "cities" (esp. the many large coastal ones), "grocery stores", "phones", & "hospitals".

     My guess is that not all humans would die from hunger, increased health risks with broken sanitation and medical services, or war violence by other humans competing for reduced resources. I think there will be survivors.  Some. 
     How many, living how and where, I am less sure about.
     I wouldn't count on one-day Amazon delivery, an internet connection, or an electricity grid.
     "Do it yourself" would evolve from an interesting hobby to a survival skill.

     At least the obesity epidemic is likely to be reduced, if only because there are several billion fewer people to count.

     And if you think this view is pessimistic, ask yourself if you too have considered some dire projection for 2050, 2070, or 2100; did the math in your head; and concluded "Well, i'll be dead by then anyway".  Is "Better dead than alive" not the ultimate pessimism?  What does that view of the future say about our honor, our legacy, and our responsibility to people younger than ourselves?

     Remember/imagine a time when you looked FORWARD to the future with anticipation for all the cool stuff that was/is being invented by truly awesome human ingenuity.  I want to get back to that.  I think/hope (depends on the day) we can get back to that.  We better. 

    Sorry for preaching, but there is nothing more important than this topic.  Nothing.  Because it affects everything.

3
Arctic sea ice / Re: "Stupid" Questions :o
« on: December 07, 2019, 12:21:12 AM »
1. From The brutal logic of climate change
By David Roberts on Dec 6, 2011
https://grist.org/climate-change/2011-12-05-the-brutal-logic-of-climate-change/

Kevin Anderson, former Director, U.K. Tyndall Energy Program.
“...a 4 degrees C future is incompatible with an organized global community,
is likely to be beyond ‘adaptation’,
is devastating to the majority of ecosystems,
and has a high probability of not being stable.”


**************************
2. From:  Turn Down the Heat - Why a 4°C Warmer World Must be Avoided, A Report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics.  2012
http://documents.worldbank.org/curated/en/865571468149107611/pdf/NonAsciiFileName0.pdf

"The 4°C scenarios are devastating: the inundation of coastal cities; increasing risks for food production potentially leading to higher malnutrition rates; many dry regions becoming dryer, wet regions wetter; unprecedented heat waves in many regions, especially in the tropics; substantially exacerbated water scarcity in many regions; increased frequency of high-intensity tropical cyclones; and irreversible loss of biodiversity, including coral reef systems. 
     And most importantly, a 4°C world is so different from the current one that it comes with high uncertainty and new risks that threaten our ability to anticipate and plan for future adaptation needs."

"It would be so dramatically different from today’s world that it is hard to describe accurately; much relies on complex projections and interpretations."

"We are well aware of the uncertainty that surrounds these scenarios and we know that different scholars and studies sometimes disagree on the degree of risk."

"Finding ways to avoid that scenario is vital for the health and welfare of communities around the world. While every region of the world will be affected, the poor and most vulnerable would be hit hardest.  A 4°C world can, and must, be avoided.

"Warming would not stop there. Because of the slow response of  the  climate  system,  the  greenhouse  gas  emissions  and  concentrations  that  would  lead  to  warming  of  4°C  by  2100  would  actually commit the world to much higher warming, exceeding 6°C or more, in the long term, ..."

********************
3.  From Climate tipping points — too risky to bet against
Timothy M. Lenton, Johan Rockström, Owen Gaffney, Stefan Rahmstorf, Katherine Richardson,
Will Steffen & Hans Joachim Schellnhuber, Nature.  27 November 2019
https://www.nature.com/articles/d41586-019-03595-0

"We argue that cascading effects might be common. Research last year analysed 30 types of regime shift spanning physical climate and ecological systems, from collapse of the West Antarctic ice sheet to a switch from rainforest to savanna. This indicated that exceeding tipping points in one system can increase the risk of crossing them in others. Such links were found for 45% of possible interactions.

In our view, examples are starting to be observed. For example, Arctic sea-ice loss is amplifying regional warming, and Arctic warming and Greenland melting are driving an influx of fresh water into the North Atlantic. This could have contributed to a 15% slowdown since the mid-twentieth century of the Atlantic Meridional Overturning Circulation (AMOC), a key part of global heat and salt transport by the ocean. Rapid melting of the Greenland ice sheet and further slowdown of the AMOC could destabilize the West African monsoon, triggering drought in Africa’s Sahel region. A slowdown in the AMOC could also dry the Amazon, disrupt the East Asian monsoon and cause heat to build up in the Southern Ocean, which could accelerate Antarctic ice loss."

 "...the Earth system has been unstable across multiple timescales before, under relatively weak forcing caused by changes in Earth’s orbit. Now we are strongly forcing the system, with atmospheric CO2 concentration and global temperature increasing at rates that are an order of magnitude higher than those during the most recent deglaciation."

Atmospheric CO2 "... is rapidly heading towards levels last seen some 50 million years ago — in the Eocene — when temperatures were up to 14 °C higher than they were in pre-industrial times."

"If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization. No amount of economic cost–benefit analysis is going to help us. We need to change our approach to the climate problem.
     Act now
In our view, the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute "

4
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 06, 2019, 01:10:47 AM »
Remember, all those MTs of CO2 are actually CO2e. We may emit that much sooner than you might think.
Agreed Tom. Though I am often not sure if people actually mean CO2e when they throw out cumulative emissions values.  But unless they specify CO2e one has to assume they mean what they say, i.e. CO2. 

Thus, as you point out, the real situation with CO2e increasing even faster makes the siutation... more worser?  Climate change trajectories are so bad they require new language. 

5
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 06, 2019, 12:31:56 AM »
Correction
   N&S 2018 correlation of ASI Extent with cumulative CO2 emissions puts the cumulative chance of 1st Aug. and Sept. as 'largely ice free' (which from my guesswork seems to line up with ca. < 2M km2 Extent, details later) at >50% chance by 2033, and regularly (individual year chance > 50%) by 2036.
     Finally, N&S 2018 give correlation of CO2 with July - October being "largely ice free" (which as above, I interpret as ca. < 2M km2 Extent).  For that I used observed emissions through 2019, and Intl Energy Agency emissions trend forecast of 1.1% continued emissions growth out to 2040, then reducing subsequent global emissions as per the observed US and EU combined downward trend since their recent peak.  With those CO2 assumptions, the cumulative 50% chance for a 1st July-Oct  that is "largely ice free" is by 2045, and regularly (individual year chance > 50%) by 2048. 
   -- Rereading Strove and Notz 2018 (which is a 19-page textbook on Arctic sea ice situation as of Sept. 2018, and serves as a background info for the more applied Notz and Stroeve 2018 companion article), I find this statement:
"Extrapolating the linear relationships into the future, we find that the Arctic Ocean completely loses its ice cover (emphasis mine) throughout August and September for an additional roughly 800 ± 300 Gt of anthropogenic CO2 emissions. For an additional 1400 ± 300 Gt of anthropogenic CO2 emissions, we estimate the Arctic to become sea-ice free from July throughout October ..."

    Those are the CO2-ASI correlations I used for that prior post, and it seems I was far too lukewarmist in my interpretation of what was meant by "largely ice free" in the companion Notz and Stroeve article.  Thus, instead of those projected dates being when Aug-Sept, or July-Oct could get below 2M km2 Extent, they may actually be estimates for when those months can have virtually Zero Extent.   Ouch.  I keep thinking climate projections can't get worse, then they do.

     But just to keep things confusing, I settled on the meaning of Aug-Sept being "largely ice free" as < 2M km2 Extent because the extrapolated dates for N&S Aug-Sept "largely ice free" almost match the N&S extrapolated dates for Sept. <1M km2, and the fact that Aug Extent runs about 0.8M km2 higher than Sept Extent.  So my original interpretation still makes more sense to me, but hard to argue against statement by same two authors writing about the same topic at the same time.  So take your pick, and 'Caveat emptor'.  Either way, it doesn't give the Arctic sea ice much time.

   What remains the same is that the timing depends upon the future emissions trend.  The CO2 regime I used assumes that global emissions do not peak until 2040 (as per 2019 IEA estimate).  Unfortunately, that seems to be a plausible scenario.  As suggested by S&N and N&S papers, that emission scenario obliterates ASI in Aug-Sept by the mid 2030s, and for July-Oct by the late 2040s.  That is not a good prospect for human civilization.  But it does not have to be that way.
 

6
Arctic sea ice / Re: Global sea ice area and extent data
« on: November 15, 2019, 11:15:37 PM »
I compared the actual JAXA extent data with the averages from 1980s to 2010s.
Arctic sea ice extent of 2019 is 4 days behind schedule if compared with the 2010s average. In the Antarctic 2019 is ahead by 7 days, which sums up to 11 days of difference.
These differences are bigger in comparison with earlier decades:
2019 vs 2000s: 15 days Arctic, 8 days Antarctic = 23 days
2019 vs 1990s: 25 days Arctic, 8 days Antarctic = 33 days
2019 vs 1980s: 29 days Arctic, 9 days Antarctic = 38 days
This is a difference of more than a month!

    That is an interesting way to capture the trend Stephan.  Perhaps we can compare the invidual decadal rates by subtracting each one from the previous decade.  (I think but not sure this is kosher.)
     Thus 1990s vs. 1980s:    5 more days
             2000s vs. 1990s:  10 more days
            2010s vs. 2000s:   23 more days
            2020s vs. 2010s:   46 more?? more days (since there a doubling for each previous step)
     Just a wild guess.  There may be constraints on continued growth at a doubling every decade.

The Arctic-only version:
            1990s vs. 1980s:    4 more days
             2000s vs. 1990s:  10 more days
            2010s vs. 2000s:   15 more days
            2020s vs. 2010s:   20 more??  (since each prior step added about 5 days)

The Antarctic-only version:
            1990s vs. 1980s:    1 more day
             2000s vs. 1990s:   0 more days
            2010s vs. 2000s:    8 more days
            2020s vs. 2010s:    8 more??  (since previous step added 8 days)

     At first glance, you might think that the big difference in the Arctic vs. Antarctic trends shows a problem with using this method.  But I think it reflects an actual characteristic of the data.  In the 1980s and 1990s, the Antarctic sea ice was not showing a trend from global warming. 

     I'm surprised that the Antarctic 2010s vs 2000s even showed an increase because I thought it was only in the last few years that Antarctic sea ice Extent was declining.  (or am I completely misunderstanding the dates Stephan is citing for Antarctic sea ice?)

     That possible rapid acceleration for the Arctic looks worrisome.  Good thing we have smart and wise political leadership at the helm to steer us through what could be a time of difficult choices and profound but necessary changes to reduce the harm.
      What... we don't have that?   Uh oh. 


7
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 15, 2019, 10:03:16 PM »
After looking at graphs of individual seas and making comments on them, this is the quote that seems valid, and  even more so, for many of the individual seas.

Changing state of Arctic sea ice across all seasons
Julienne Stroeve and  Dirk Notz

Quote
5. Accelerated sea ice loss during all months of the year is additionally driven by a lengthening of the melt season. As assessed for the Arctic as a whole through April 2018, melt onset is occurring 3 days earlier per decade, and freeze-up is happening 7 days later per decade (figure 3). Over the 40 year long satellite record, this amounts to a 12 day earlier melt onset and a 28 day later freeze-up.
[/size]

The summer melt turns from a V shape  into a U shape

     Interesting graphical insight gerontocrat.  Seeing those V curves turn into flat bottomed U shapes is a useful visualization of the concept of individual Arctic seas reaching cumulative losses to the point of having temporary ice extinctions.

      Another insight arises from reading your quoting item 5 about the Arctic as a whole gaining 10 days of melt season per decade (starts 3 days earlier, ends 7 days later per decade).  That trend gives a shorthand way of projecting dates for when additional BOE landmarks will occur.  If that rate continued, then once we have September regularly going below the 1M km2 BOE threshold, then every 3 decades after that, at the 1979-2018 melt season expansion rate, the duration of the BOE period would expand by another 30-days.

      I suppose the added low ice/BOE period would be an additional 9 days before and 21 days after the date of annual minimum.  Seems to me that the low ice period would continue to expand forward and backward from the current mid-Septemberish date for annual minimum at the same ratio as before.  Or will that the ratio change as the ice-free period runs into the darkening days of October vs. the sunny dog days of August?  Why is the observed ratio not not the same on either side of the annual minimum, i.e. why 3 days earlier start but 7 days later finish instead of 5 & 5?

     Correlation of global average surface temperature and cumulative CO2 emissions with Arctic sea ice decline stated in the Notz and Stroeve 2018 article at  .....
https://forum.arctic-sea-ice.net/index.php/topic,2348.msg236344.html#msg236344
   ( Oy, citing my own ASIF posts - all I need now is the ability to Like them and my little bubble of narcissism would be complete.  Maybe we should give Trump a special ASIF member privilege to do that in hopes that it would provide a relief valve for his apparently bottomless need for affirmation, and cut back on his Twitterbation.  By now he must be developing the apocryphal hairy thumbs. 
Double oy - I usually discover later than what I criticize in others is often a reflection of some aspect of myself!  So I am ending this digression right now.)

..... suggest a much faster expansion of melt season for the Arctic as a whole than a new month every 30 years.   I suspect that is because the 3 days earlier - 7 days later per decade trend, being based on the 1979-2018 record, is slower than the rate of melt season advancement more recently.  I'll take a second look at Notz and Stroeve to see what date estimates can be extracted for when BOE for Aug, Oct, and July might be expected based on current trends. 

8
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 15, 2019, 01:12:12 PM »
      Yeah that one kind of stuck out to me too.   But in my haste I didn't think about it long enough to realize that by removing it from its surrounding context it wasn't adding value. I think the larger point was that the transition of the Arctic seas, and the Arctic as a whole, from one mode and system state to a new condition happens gradually for a long time, then all of sudden it's done.  Similar to thin edge ice hanging on for a long time until it seemingly goes poof. 

       But you are right, the statement standing alone just looks dumb due to my editing, not the author's original intent.  I have taken it out since by itself it doesn't add value.   

         My editing glitches aside, the Stroeve and Notz, and the Notz and Stroeve 2018 papers together serve as a good comprehensive and fairly up to date (changes every day!) primer to the ASI story.  It addressed a lot of the questions I had in an understandable plain language way, and the authors are recognized experts in that arena.  Both articles are free online with open access (no paywall). 

9
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 14, 2019, 11:32:42 PM »
      Neven has said he does not like long wordy posts, which this certainly is.  If it violates some ASIF code I am unaware of and it gets snipped, no offense taken.  I wanted to make these excerpts for my own use anyway.

     This post consists of some of the best sentences from the paper cited below.  The whole paper is well worth reading and is written in understandable language.  They do dig into the details of various sensors in the methods section, but you can gloss over that stuff. 

     By the way, if you are not used to reading science journal articles, here is a little secret.  Almost nobody completely understands every sentence.  Sometimes not even the authors.  You learn how to read to get what you can get and when it gets obscure you just move on.  Always good to start with the abstract, then it is fair game to skip to the conclusions, and look at some graphs along the way to decide if you to read the whole thing.  Sorry if this comes across as patronizing.  I just figure a lot of people are not used to professional "science culture", I know I certainly had no clue about it through 7 years of on-again off-again undergrad.  Once you realize it is just people, it becomes less intimidating and more fun.

     As for protocol and rightful use of such extensive quoting, the source article has a license statement that looks favorable. "Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.  Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI."

     These topics arise repeatedly in the forum and Stroeve and Notz do a nice job of laying it on the table.  My guess is that as the paper is over a year old and as they are passengers on this planet too, Stroeve and Notz would approve of using the forum to spread their findings.

Source for all of the excepts below:
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and  Dirk Notz
2018 Environ. Res. Lett.13 103001
https://iopscience.iop.org/article/10.1088/1748-9326/aade56

        Placement of "-------" indicates larger than usual amount of text was skipped prior to following quote.  All right, here we go.
--------------------

    “There are two ways in which the climate system can reduce the amount of sea ice within the Arctic Ocean:  first by local melting within the Arctic Ocean, and second by export of sea ice through outward sea ice drift. As outlined in the following sections, a number of studies have found the local melting of sea ice to be by far the main contributor to the observed loss, and we hence need to identify the main driver for increased sea ice melting if we are to identify the main driver for the substantial sea ice loss in recent decades.”
--------------

"4.2. Stability of the ice cover
    In addition to changes in the external forcing and internal variability, a self-amplification of the ongoing ice-loss could in principle have contributed to the rapid ice loss in recent years. Such self-amplification is usually discussed in the context of so-called tipping points or nonlinear threshold, which are often defined as processes in the climate system that show substantial hysteresis in response to changed forcing.

     The best known example for such possible hysteresis behavior is related to the ice-albedo feedback  mechanism: a reduced ice cover in a given summer will cause increased absorption of solar radiation by the ocean, contributing to further reductions in the ice cover.  Such positive feedback loop can cause the irreversible loss of Arctic sea ice in idealized studies based for example on energy-balance models (see review by North 1984), and have hence been suggested to possibly  be relevant also for the real world.

     However, an analysis of the existing observational record and a substantial number of respective modeling studies with complex ESMs all agree that such a ‘tipping point’ does not exist for the loss of Arctic summer sea ice. For example, Notz and Marotzke (2012) found a negative auto-correlation of the year-to-year changes in observed September SIE. Hence, whenever SIE was substantially reduced in a given summer, the next summer usually showed some recovery of the ice cover. This was further supported by Serreze and Stroeve (2015). Such behavior suggests that the sea-ice  cover is at least currently in a stable region of the phase space, as otherwise one would then expect that any year with a really low ice coverage should be followed by a year with an even lower ice coverage, driven by the ice-albedo feedback mechanism. As shown by Tietsche et al (2011), the contrasting behavior of the real ice cover can be explained by compensating negative feedbacks that stabilize the ice cover despite the amplifying ice-albedo feedback. The most important of these stabilizing feedbacks relates to the fact that during winter the ocean very effectively releases heat from those areas that became ice free during summer, thus over-compensating for any extreme ice loss in a preceding summer. Ice that is formed later in the season also carries a thinner snow cover and can hence grow more effectively during winter (e.g., Notz 2009).  Stroeve et al (2018) suggest, however, that this stabilizing feedback mechanism is becoming weaker and weaker as Arctic winters become warmer and warmer.  Increased winter cloud cover after summer sea ice loss as found by Liu et al 2012 also weakens the stabilizing
feedback, as it reduces the loss of heat from the ocean surface."


10
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 14, 2019, 03:22:00 AM »
This situation is getting worse fast

From today
The Arctic's Most Stable Sea Ice Is Vanishing Alarmingly Fast
By Mindy Weisberger
https://www.livescience.com/arctic-ice-refuge-vanishing.html
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2019GL083722

From August 2018.
'Archived' heat has reached deep into the Arctic interior, researchers say
By Yale University.
https://phys.org/news/2018-08-archived-deep-arctic-interior.html
https://advances.sciencemag.org/content/advances/4/8/eaat6773.full.pdf
Thanks to ArcticMelt2 for bringing attention to this one with post at
https://forum.arctic-sea-ice.net/index.php/topic,2888.msg236503.html#msg236503

"The upper ocean in the Canadian Basin has seen a two-fold increase in heat content over the past 30 years, the researchers said. They traced the source to waters hundreds of miles to the south, where reduced sea ice has left the surface ocean more exposed to summer solar warming. In turn, Arctic winds are driving the warmer water north, but below the surface waters.

"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." "

The region discussed in the second article abuts the area described in the first article, i.e. the wedge of thickest overwintering that runs from the north coast of Greenland along the northern edge of the CAA. Not a good place to store a reservoir of warm water.


11
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 12, 2019, 04:50:20 PM »
Edited quote
Since the third term is a calculated average (and not a finite measure as the other two) then flipping them around makes no sense.

At least we have identified where we disagree,
I submit that mathematically all are true.
E*T=V
E = V/T
T = V/E

It does not matter to their mathematical relationship which one you solve for, the relation stays the same.  In your examples you solve for T based on set values for E and V, and you get a T that is greater than E.  But that is not an inherent requirement.  It is simply an artifact of the values you set for E and V.  You could set E and V to different values and find that the resulting T is less than E.

For example:  As you found
 If E = 0.99 and V = 0.98
then T = V/E = 0.9898
T decline (=1 - 0.9898) is greater than E (1-0.99).

 But
 If E = 0.9898 and V = 0.98
then T = V/E = 0.99
T decline (=1 - 0.99) is greater less than E (1-0.9898)

It does not matter which is directly measured and which is inferred.  Mathematically they are all equally real.  (And BTW, Thickness IS measured.  Volume is calculated from Extent and Thickness).
But if you want to define E and V and then calculate T, that is fine.  Doing so does not require T to be smaller or larger than E.  All that matters is the relative sizes of the E and V values you choose.  Specifically, if E - V is larger or smaller than 1 - E 

For example, if E = 0.9 and V = 0.85,
T = V/E
T = 0.94
T is larger than E
 E - V = 0.05
1 - E = 0.1
E-V is less than 1-E, so T is greater than E

 if E = 0.95 and V = 0.85,
T = V/E
T = 0.89
T is less than E
E - V = 0.10
1 - E = 0.05
E-V is larger than 1-E, so T is less than E


RE:  Oren.  Close but no cigar.  You are using E + T = V. 
It is  E * T =V.
Multiplication vs. Addition.

Addendum to the end game scenario.  Extent losses are largely due to the loss of thin ice at the edge of the pack.
As the pack shrinks, that edge area becomes an increasing proportion of the total pack area.  Circumference to area ratio gets larger.
 
(This is analogous to the surface to volume ratio that lets insects do things we can't, and also why insects have to be small to do what they do, but I digress)

So, as the percentage of the total ice pack subject to edge area losses gets larger, the percentage rate of Extent losses will increase. 

***Not sure about this next statement.  Math fatigue setting in.***
The straight line trend for Extent losses will begin to curve downward unless it is counteracted by a decline in rate of thickness loss around that edge, which does not seem likely.

*** Then again, the absolute amount edge = Extent loss would not increase, and in fact with smaller absolute edge area, absolute Extent losses would decrease.  But the amount of extent loss would be higher ratio relative to the amount of previous year Extent.  So it may just come down to whether you report Extent losses as absolute number of km2 or % of previous year.  Math fatigue now math exhaustion.  This is becoming a "how many angels fit on the head of a pin discussion".  Who cares.  It does not matter. 

    What matters is that the ASI is nosediving.  Because of albedo and other effects, how the Extent trend will evolve is of interest.  Thanks to Notz and Stroeve and their colleagues, we have insight on how the ASI situation will dramatically evolve over the next 10-30 years.  It is a scary, ominous story.  Maybe if the immediacy of ASI collapse is better understood it will help us make difficult decisions to reduce the damage we are doing to ourselves.




12
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 12, 2019, 06:54:21 AM »
Edited quote
As an example, if extent is falling by 1% per year, and volume by 2%, then thickness falls by very close to, but ever so slightly above, 1%. If extent is at 1% and volume at 3%, thickness clocks in at slightly above 2%.

Try one more cup of coffee and you may reach a level of caffeine induced enlightenment where this becomes obvious. ;D

Using your example, but merely flipping Thickness and Exent:
If Thickness is falling by 1% per year, and volume by 2%, then Extent falls by very close to, but ever so slightly above, 1%.
If Thickness loss is at 1% and volume at 3%, then Extent clocks in at slightly above 2%.

In your example, Thickness loss is always a bit greater than Extent loss.  In my flipped version, Extent loss is always a bit greater than Thickness loss.  You say TomAto, I say ToMAHto! :o

The point being that either the Thickness term or the Extent term can be the larger of the two.  It does not matter.  Either way, when they are both are negative, the resulting product of their multiplication (i.e. Volume) is smaller than either of them individually.  So when Extent trend is negative, AND the Thickness trend is also negative, then the Volume loss has to be more negative than either the Extent or Thickness trend individually.  But as for Extent and Thickness, either one of them could more more negative than the other.

13
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 12, 2019, 06:11:30 AM »
Well if binntho agrees with me, he must be right! 

    But here is another perspective about a possible Extent pause.  I am (almost) sure that if Tamino bit into the Extent numbers he would, as he did with global average surface temperature faux pause, show that there is no statistical justification for the relatively small number of yearly data points in the presumed Extent hiatus period to be called a significant violation of the long term linear trend that is derived from a much larger set of of data points with considerable year to year variability.  (BTW Tamino's wife announced on his blog that he had surgery recently.  Sending him wishes for healing and good health.) 

    But I submit to the jury that even if Extent did have a statistically valid hiatus, it would not matter.  There could be a scenario where Volume losses continue their inexorable decline, yet a prolonged series of years with conditions favorable for greater ice dispersion resulted in Extent value flat-lining for enough years in sequence to pass a statistical test for truly being a hiatus.   

     But so what?  In terms of progressive ice decline, that would not change the underlying fact that Volume losses were still proceeding toward zero.  A hiatus in Exent would only temporarily increase the discordance between the Extent and Volume trends.  The increased difference would have to be compensated for at the end.  The only consequence of an Extent hiatus would be that the Extent trend would have to fall that much farther faster when the zero Volume-Thickness-Extent day of no ice reckoning finally arrived. 

    The 10-30 year lag for the majority of global warming impact from elevated greenhouse gas levels to be expressed means that the warming and ice melt trends for the next 10-30 years have already largely been set by our previous emissions.  The fact that the trend-projected date for the first zero ASI Volume event is now within the next 20 years means that it is probably unavoidable at this point even if we sharply reduced further GHG additions.  Then again, Notz and Stroeve point to an 800 Gt CO2 of additional emissions needed after 2018 for the total GHG load to be enough to result in Volume reaching zero.  So in theory at least, keeping total emissions below that amount could presumably prevent the Volume losses from reaching the zero point. 

     (On the other other hand, --- running out of hands ---, I suspect that even if emissions ceased immediately, with enough time and the slow depletion of existing CO2 from the atmosphere, even the GHG emissions already made thus far, bolstered by some permafrost thaw and other feedbacks, would eventually result in ASI Volume-Thickness-Extent reaching zero.)

     That is a moot point for the real world situation.  It does not seem at all likely that humans will cut emissions sharply enough and soon enough to prevent exceeding the 800 additional Gt CO2 after late 2018 threshold.  And therefore, assuming the Notz and Stroeve relationship between total CO2 emissions and ASI Volume is correct, the Extent trend will meet up with the Volume trend at the zero point.  Which year that happens depends on how fast we move towards that 800 Gt CO2 post 2018 threshold.  This being the end of 2019, we have probably reduced the remaining budget to 760 already. 

     Extent can go where it will prior to the zero day of reckoning, but when the Volume trend reaches the point where there is no ice to spread around, Extent will also be at zero.

   Edited quote
And we already know that volume is falling faster than extent, which means that thickness is falling faster than extent.
    I don't agree with the second part, "... which means that thickness is falling faster than extent. " 
    Yes, we know that Volume is falling faster than Extent.  Because Volume is the product of Extent x Thickness, Volume has to fall faster than Extent unless there is either Thickness gain or zero loss.  But Thickness does not have to fall faster than Extent for Volume loss to be less than Extent loss.  It does not matter which of two (Extent or Thickness loss) is greater, or if they are exactly equal, all that matters is the product of Extent x Thickness, because that is what defines Volume.

   

14
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 11, 2019, 11:53:08 PM »
Edited quote
... this short video of ice melting explains why I think it will look basically okay in terms of area and extent right up until it isnt.



Nice.  Exactly!  Watch the footprint of that ice cube as it melts.  The area covered declines at a much slower rate than volume as the thickness declines.  Until the thickness gets so small that continued losses come at the expense of the area covered (Extent).  Then it rapidly declines at the very end as Extent loss (footprint) finally catches up the Volume loss (shrinking ice cube).

15
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 11, 2019, 11:17:09 PM »
Conversely, volume cannot be zero, if extent and thickness are not.  Volume, being three-dimensional, will always change faster than thickness (one-dimensional) or extent/area (two-dimensional).  At some point, they must converge.  What is your reasoning to believe that volume is the key metric over the others?

I agree that "At some point, they must converge."  That was the reason for my quest -- (cue Man of La Mancha music): How/when will the Extent trend and Volume trends meet?

I suppose you can frame the same question as "When will the Volume trend flatten out so that it can meet the Extent trend?"  I don't see reason for that to happen.  The linear volume trend looks pretty inexorable.  And while, as gerontoacrat noted, Volume measurement has its problems, Extent is not so pristine either.  A pixel with 16% ice counts as 1, with 14% counts as 0; melt ponds misidentified as open water etc. 

     And even if measured perfectly, Extent in the real world is subject to being altered by wind patterns, compaction vs. dispersal.  That is also why I think 2012, while certainly an important event as we watch the ASI go down the tubes, is overrated.  It was hyuge (new American English spelling, as in 'our politics and planet are hyugely screwed up') Extent event, but a less cataclysmic Volume event, and thus less of an informative marker for progressive ASI decline.  Thus Extent is the more mercurial hare, subject to temporary conditions, while good ole Volume is the sober implacable tortoise plodding its way towards cryospheric Armageddon. 

Maybe it is arbitrary that I start with the presumption that you can't have Extent of ice without any Volume of ice to create it.  But that makes more sense to me than the other way around.  Stuff has to exist before you deal with how it is spread around.

I am more likely to buy into gerontocrat's argument that the Volume measures are more subject to error, so this discordance between the Extent and Volume trends (that I repeat, we all agree have to meet up in the end) could be due to spurious Volume measurements.
.... But not really.  Because it makes perfect sense that what we see (Extent loss) is multiplied by what we can't see (simultaneous Thickness loss) to create Volume losses that are bigger than Extent losses.  In fact, the only way Extent losses could keep up with Volume losses is if there was NO Thickness loss. So of course Extent losses lag behind Volume losses.  How could it be otherwise? 

    And it makes sense to me that Thickness is being affected by the same forces that are depleting Extent and Volume.  And it makes no sense to think that Thickness is not being depleted.  And regardless of what you or I think, hard working scientists and other folks take measurements that show that Thickness is indeed going down.

I defer to the great Juan C. Garcia.  His message tag line points to Volume losses being a more important indicator than Extent because Extent, as you noted, is missing a dimension, the key dimension of concurrent thickness losses. 
"Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost."

16
Arctic sea ice / Re: Latest PIOMAS update (November 2019)
« on: November 11, 2019, 10:27:01 PM »
Not that I remember the math that well, but an X2 curve will ALWAYS give a better fit than a linear X curve.  And an X3 curve will ALWAYS give a better fit than an X2 curve.

 I will always treasure the moment when some new grad students showed results from a class lab experiment with six data points on an XY curve all over the place like a sneeze and got a perfect correlation with a wiggly X5 curve!  Which is what has to happen when you use up every last degree of freedom.

17
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 11, 2019, 09:04:51 PM »
Also from Notz and Stroeve 2018
“Also for the future, no substantial self amplification of the summer ice loss is expected. In particular, in all models that participated in CMIP5, the linear relationship between Arctic sea-ice cover and global-mean temperature holds until all sea ice is lost. This behavior already takes into account that in many regions, the ice-free duration during summer is becoming longer and longer, and that the ice cover as a whole is getting thinner. These factors are apparently not sufficient to overcome the stabilizing feedbacks and do not cause an acceleration of the summer sea-ice loss.”

    This seems to put to rest hope for a slowdown in ASI losses due to the final ice being at higher latitude.  Notz and Stroeve discuss and dismiss the opposite potential for reinforcing feedbacks to accelerate the rate of decline.  That does not leave much room for a slow down.
   
Stroeve & Notz papers
To state that the linear relationship between sea ice loss and Arctic Global-mean(?) temperatures will hold until there is no more ice is heroic indeed.

How do they deal with September sea ice loss 1979 to 2019 of around 50% and volume loss of around 75% ? If both continue at the same linear rate then an arithmetical impossibility looms.

     What got me started on all this was the discrepancy between the Extent and Volume trends.  Since Extent has to reach zero at the same time as Volume, my query was how much longer before the Extent curve bends down to a necessary eventual reckoning with zero Volume?  Shared Humanity's comment about ice going poof is worth more than what he supposes is its current market value!  It got me to realize that the Extent curve does NOT have to bend down to meet the Volume trend, at least not until the last day.

     Volume is a product of Extent x Thickness.  We've lost about 76% of Volume (based on PIOMAS Sept. Volume trend for 2019 vs.1979), but only about 42% of Extent (based on NSIDC Sept. Extent trend line for 2019 vs. 1979). 

     The Extent value gets multiplied by the Thickness value to get Volume.  So Extent can keep on floating down at a less steep slope until the point at which Thickness gets so thin that it falls prey to a warming event that takes Thickness down to zero.  That is the "poof" moment when Extent suddenly catches up to Volume, i.e. they both reach zero.   

    Figure 6 in the Strove and Notz, 2018 cited in previous post shows that 10-day Extent losses of 1M km2 have occurred, and that losses of at least 0.5M km2 are not that rare.  Thus, once Extent  gets into the range of less than 2.0M to 1.5 km2, there is a possible and increasingly likely chance of a "poof" event of 0.5 to 1.0km2 scale that takes Extent below the arbitrary 1.0M km2 BOE threshold.  That provides an indicator for how much longer Extent losses can continue at a slower pace than Volume losses before a fluctuation in Thickness creates a first time BOE.   

    The Sept. 2019 NSIDC Exent was 4.32M km2.  As per NSIDC "The linear rate of sea ice decline for September extent from 1979 to 2019 is 82,400 square kilometers per year."

    To reach the 2.0M Extent when a poof Event becomes possible, would require losing another 2.3M km2 of Sept Extent below the 2019 value of 4.3 (which is pretty much on the Trend line).  By this reasoning, at 82k per year losses, losing 2.3M km2 would take another 28 years, i.e. 2047 before Extent in 50% of years would be within plausible range of a poof event. 

    This is later than I had expected, since Notz and Stroeve put the 50% chance of any single year going below 1.0M km2 as 2038.  By 2047, Notz and Strove estimate that >95% of individual years will go below 1M km2.

    Hmmm?  So Extent trend alone does not end up at the expected date for 50% chance of BOE.  That leaves Thickness losses as the missing factor that aligns the NSIDC Extent trend with the Notz and Stroeve BOE dates.  And that makes sense. 

     Stroeve and Notz Fig. 5 show the decline of April ASI Thickness, and they cite the PIOMAS April Thickness trend as -0.28M per decade.  Looking at PIOMAS Sept. thickness linear trend, I get a very similar -0.27M/decade trend.  So by 2038, absent any acceleration or deceleration of Thickness losses, the average Sept. ice Thickness is likely to be near 0.51M.  As Thickness declines from 1.022 (Sept. 2019) to 0.51M, the frequency of 0.5 to 1.0 km2 Extent losses in a 10-day period will certainly increase, and the magnitude of infrequent large scale Extent losses will also increase. 

    That is why extrapolation of the Extent loss curve alone yields BOE dates that are artificially late.  Combine the continued Extent loss curve with an increasing (instead of static) scale for 10-day Extent losses (due to declining Thickness), then you can get dates to fit with the Notz and Stroeve estimate of 2038 for when 50% of years could reach BOE status of <1.0M km2.

     In 20 years, the Extent trend goes to 4.32M - (0.084M x 20) = 2.67M km2.  That is way too high to be taken down to 1.0 km2 by a 10-day Extent loss event if the September Thickness remained at the current ca. 1.02M.  But much more likely when the average September Thickness is down to 0.51M.

   So here we have the most likely poof moment scenario for when ASI goes below 1.0m km2.  Around 2038, with Sept. Extent at ca. 2.7M km2 and Thickness is down to 0.5M, a 10-day event removes enough ice to take Extent below 1.0M km2.  (This scenario also fits well enough with Archimid's April max vs. summer losses crossing trendlines.)

    Of course, this is an event of arbitrary significance.  The ice will begin refreezing and our long march to a hot Earth destiny will continue with ups and downs in ASI.  Deniers will cite the fact that Arctic ice coverage in October increased over September to show that there is nothing to worry about.

    As for thin ice melt acceleration, which is also where this adventure started, I stand corrected and have to yield to more educated minds that reversing the Thorndike curve is not legitimate in terms of thickness alone and thermodynamics.  But as Shared Humanity noted, my gut still says that in a real world setting, younger, saltier, highest-surface-to-volume-ratio, more fractured, dispersed, thinner ice has a higher chance in a rolling ocean exposed to currents to get melted by export or to go poof due to flash melt, and that the chances for rapid Extent loss increases faster than the linear change in thickness.  But now I'm just being stubborn. ;D

     I don't know if this convinces anybody else, and there remains the chance of some bonehead error that makes this all wrong, but thanks to the Stroeve and Notz articles I feel like I have some understanding for how the Extent, Thickness, and Volume trends will evolve over the next 20 years.  The Emperors are well dressed indeed, and I retract my arrogant and ignorant allegations to the contrary. 

     

18
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 11, 2019, 06:52:12 PM »
     Having flaunted my ignorance in public in this thread, I am chagrined and pleased to report that the experts have in fact already spoken.  I just wasn't listening.  "Ask and ye shall find that ye have already received, ye just weren't paying attention!"
     Two excellent September 2018 articles, both online with open access:

Changing state of Arctic sea ice across all seasons
Julienne Stroeve and  Dirk Notz
2018 Environ. Res. Lett.13 103001
https://iopscience.iop.org/article/10.1088/1748-9326/aade56

The Trajectory Towards a Seasonally Ice-Free Arctic Ocean. 
Dirk Notz and Julienne Stroeve.
Current Climate Change Reports (2018) 4:407–416
https://doi.org/10.1007/s40641-018-0113-2
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6411203/pdf/40641_2018_Article_113.pdf

Excerpts from Notz and Stroeve, 2018.

“…we find that the temperature at which the Arctic first becomes ice free will have a 95% uncertainty range from internal variability of ±0.2 to 0.4◦C. These values are in line with results from large-ensemble model simulations. Combined with the temperature threshold of less than +2◦C for a near ice-free ocean during summer, this then implies low, but above zero chances for a near-ice free Arctic ocean at + 1.5◦C global warming.”

“….the 95% uncertainty range for cumulative future emissions of CO2 leading to an ice free Arctic Ocean during summer becomes 500 to 1100 Gt based on the average value of 800 Gt established above. For a given emission per year, this uncertainty range can be translated to an uncertainty range of the year when the Arctic first becomes ice free.  For today’s emission of about 40 Gt CO2per year, we get an uncertainty range of about 15 years,…”

“Based on this approach, we identify the following statements to be very likely true for the future evolution of the Arctic sea-ice cover.
1. The Arctic sea-ice cover has been and will remain linearly related to global-mean air temperature in all months. Global-mean air temperature can hence be interpreted as the most important control variable on future Arctic sea-ice evolution.

2. The observed linear relationship between Arctic sea-ice coverage and global-mean air temperature suggests Arctic sea-ice coverage to drop below 1 million km2 in more than 50% of all years for a global warming of less than 2◦C compared to pre-industrial levels.

3. The observed linear relationship between Arctic sea-ice coverage and cumulative anthropogenic emissions of CO2 suggests Arctic sea-ice coverage to below 1 million km2 for more than 50% of all years for total future anthropogenic CO2 emissions of less than 800 Gt.

4. From internal variability, September sea-ice coverage can vary by a maximum of ±1 million km2for a given global-mean air temperature.

5. This year-to-year fluctuation can directly be translated into an uncertainty of ±0.2 to 0.4C for the global warming at which the Arctic Ocean loses its summer sea ice for the first time. For CO2 emissions, the uncertainty is about ±300 Gt CO2 emissions. Hence, the Arctic Ocean can be expected to be nearly ice-free in 5% of all years for 500-Gt future CO2 emissions and in 95% of all years for 1100-Gt future CO2 emissions.

6. As the observed linear relationship between Arctic sea-ice coverage and global-mean temperature currently hold for all months, they allow us to estimate the future seasonal cycle directly from the observational record.  This is also true for the observed linear relationship between Arctic sea-ice coverage and cumulative CO2 emissions. 

Based on current emission rates of about 40-Gt CO2 per year, these findings imply a substantial likelihood of an ice-free Arctic Ocean during summer before mid-century.  The time window to prevent the loss of the Arctic summer sea-ice cover hence closes very rapidly.”

**********************
My summary of some take home messages:

    The article was written in September 2018.  At 40 GtCO2 per year, the average estimate of “less than 800” Gt CO2 for 50% chance for any single year going below 1m km2, is 20 years after 2018.  Thus, by September 2038

     Due to uncertainty in the estimate and fluctuations between individual melt years, by 2031 (500/40 = 12.5.  2018 +13 = 2031) there is at least a 5% chance for any single year going below 1m km2 Arctic sea ice cover.  With the single year chance increasing for each subsquent year.
 
     By 2046 (1100/40 = 27.5.  2018 +28 = 2046) (if emissions continue at 40 GtCO2 per year) each individual year would have at least a 95% chance of going below 1m km2.

    The Notz and Stroeve dates based on CO2 emissions also fit with dates derived from the Notz and Stroeve global average temperature - sea ice relationship (e.g. <1M km2 in more than 50% of all years at <+2◦C; 1st year <1M km2 possible at ca. +1.5C) when compared to my projection of NASS GISS global surface temperature anomalies:

Year   Projected NASA GISS vs. 1850-1900
          (Obs, ENSO and solar cycle for 2019; ENSO & solar for 2020; Solar & RCP8.5 emissions after 2020)
2019   1.20
2020   1.16
2021   1.14
2022   1.14
2023   1.19
2024   1.25
2025   1.31
2026   1.37
2027   1.42
2028   1.42
2029   1.43
2030   1.44
2031  1.45
2032   1.46
2033   1.48
2034   1.53
2035   1.59
2036   1.65
2037   1.71
2038   1.77
2039   1.78
2040   1.80
2041   1.82
2042   1.83
2043   1.85
2044   1.87
2045   1.94
2046  2.00



19
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 09, 2019, 06:46:53 PM »
http://psc.apl.washington.edu/zhang/IDAO/multi.html
Animation of ASI Thickness out to 2050 by Dr. Zhang at Polar Science Center.  Shows first BOE by the 1m km2 definition around 2032 (eyeball estimate) with some recovery years in mid-2030s.  By 2040 September min is essentially a BOE every every year and August almost as low.  By 2046 August is at or near BOE every year.  Still plenty of Extent into July even by 2050.

The page and animations are not dated.  Because they use an older emissions-warming scenario (B2) and start future projections in 2005  I assume they were created before the most recent full IPCC reports in 2013-14 (which used RCP scenarios), and probably been created ca. 2004.  A lot has happened since then.  But the animations are still interesting to watch if only too see what state of the art was at that time.

    The files ran on Windows Media Player when viewed through Google Chrome browser over home wifi.  For unknown reasons I could not view  with Firefox. First time through it had some long pauses.  Playing through 2nd time is smoother.  If you are quick with the mouse you can stop and view any single month as freeze frame.

20
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 08, 2019, 09:54:44 PM »
Ditto that request Tor.
 
RE: 
Gerontocrat, your graphs has gotten me thinking.  What if the open water in the peripheral seas is contributing to larger heat losses, resulting in faster refreeze of the CAB?  Widespread ice cover in the past may have kept more heat bottled up beneath the ice.

Uh oh, another possible Achilles heel.  And maybe that was part of the Chris Reynolds 'Slow Transition' hypothesis that I missed.  I can see how ASI refreeze declines could slow as diminishing ice cover allows more ocean heat to escape to the atmosphere during the winter.  That would stall declines in April Maximum.  But even with a semi-stabilized April max, increasing warming of the summer melt seasons would still progress toward a September minimum reaching the BOE threshold of 1M km2 Extent.

    Just to clarify, my proposition that the final meter would melt out faster is not saying that the Arctic is going to ice free year round anytime soon.  It would apply sequentially to each month as its monthly average thickness got to and below 1 meter.  Thus, September Volume and Extent losses would transition from a straight line trend down to a downward bending curve as average thickness declines.  If that is true, then it should start becoming apparent pretty soon (i.e in next 5 years) because Sept. average thickness is getting close to 1 meter.   

      See the Wipneus average montlhly Volume graph at
https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png?attachauth=ANoY7coD8qak1Y1OxDoPDEijpxlR44NBQbsfo1c5i4-Bk1Zvmt1qUiw2vkca4klldt_5e_ZfGwzmI0esENnfeDW9sXTTdna3Brr9mvGsVbPuI1oD5uyzvq7Z3D8zf2EfMCy9nnbKl45gFjfDbj6kZwFDFybvy9yhahjUNE5xVFrB84O_dzfeIEwDQDZXZVbi5nZDn9-9IBKLLbEeSE4eAnkpqcVVwWYWMVXq9QGC-BVCpuGpLMcrTZJ1srgqcr6Ut-8eYoiJQg0L&attredirects=0

      As shown on the Wipneus graph - August and October volumes only trail September by a few years.   But then there is a big jump to July and November, another big jump to December, and another to January and June.  So those later months would still have large amounts of ice for many years to come even if the fast-final-meter hypothesis is correct.

     The Wipneus graph provides some evidence to evaluate the notion that as a month reaches and goes below 1m average thickness, its losses accelerate.   The graph applies X2 curves to monthly average ASI volumes.  According to my reasoning, September should have the steepest downward curve since it is the closest to crossing the 1 meter average thickness threshold (not that there is a discrete threshold to cross). 

     And lo, the Sept. curve does bend down at a steeper rate than the July or June curves.  (August and October curves have essentially same curvature as September, Nov and Dec curves not posted for 2019 yet).  I measured curvature by comparing the left axis 1975 amount vs. the 2020 right axis amount for September vs. June or July curves.  The Sept curve is farther below June or July in 2020 than it was in 1975, so it is bending downward at a steeper rate. This is hardly a Nobel prize winning observation, but at least it fits with my hypothesis.

     But it is also true that while I am not ready throw in the towel quite yet, the more I think about this, the more I realize I am dabbling in concepts I know too little about to make meaningful conclusions.  There are books and articles to explain things like this.  We don't have to figure it out by ourselves because other people have thought about it in a lot more depth. 

      I read through the recent IPCC Cryosphere report looking for a mechanistic explanation and found surprisingly little exposition on this critically important issue.   If you know of a good summary that addresses how ASI loss trends are likely to evolve in the coming 20 years please share citation or link.  Here is one I read a while back, but need to re-read:
    Overland, J. E., and M. Wang (2013), When will the summer Arctic be nearly sea ice free?, Geophys. Res. Lett., 40, 2097–2101, doi:10.1002/grl.50316.  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/grl.50316
   
     Even though it is getting a bit dated now, it was written right after the 2012 minimum at which time ASI declines were greatly exceeding expectations.  Thus, awareness was high that the Arctic was not behaving as had been predicted.

    I wonder how many of the experts at NSIDC, NASA etc. read the ASIF.  Maybe professional etiquette prevents them from zooming in and correcting the half baked-theories posted by non-experts like me.  (Some of the folks that do post here give the appearance of being professional ASI scientists.  There is tremendous knowledge embedded in ASIF.  If the experts aren't reading it, they should because they could learn a lot too.)  But just saying "Wrong" isn't enough.  What I would like is for somebody with expertise to provide a summary of how ASI loss dynamics are likely to behave over the coming 10-30 years. 

    Specifically, I would like to read an expert opinion on whether the Wipneus volume straight line trend is expected to continue.  And if not, why not.  Because if it continues, we will reach zero average ASI in September 2032, and rapidly declining Sept. average Extent over the next 10 years as Extent losses catch up to Volume losses.  With August and October not far behind September.  That scenario has consequences for the habitability of our planet.  So it is not simply an intellectual exercise.  We really need to understand this stuff.

    Sorry for another long post.  Just trying to get it down in words.  Guess I wasn't born for Twitter times.

   

21
Arctic sea ice / Re: The 2019/2020 freezing season
« on: November 07, 2019, 09:21:11 PM »
      This might belong in the Stupid Questions thread, but can somebody explain how/why Laptev and ESS had such above average Extent and Area refreeze gains when the GFS temperature forecasts over the past two weeks have shown substantial above average temperature anomalies?

     In addition to the anomalies, some of the absolute temperature values were at or just below 0 C.  And if I remember correctly, not just 2m air temps., but also SST temps. were above normal.  So how does that turn into above average refreezing?

     I realize that those seas were starting from below average ice amount, were bound to catch up and by starting late, caught up faster than normal, and that the lack of ice cover may have allowed greater export of ocean water heat into the atmosphere.  But all of that doesn't seem to be enough to explain how such a burst of new freezing happened. 

     My guess is that the GFS air temperatures at 2 meters above the surface were reading high because of ice formation.  Thus in opposition to my assumption that elevated surface air temperatures would retard ice formation, it was the exact opposite, energy released by ice formation was warming the air.

    Regardless of my confusion based on expecting the opposite to have occurred, what explanation is there for the recent rapid ice accumulation at far above the normal rate?

22
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: November 07, 2019, 12:50:22 AM »
Apologies for taking so long to reply... I'll spare you my usual excuses, though I don't doubt they would impress you with their earnest sincerity and momentous import of the ways I manage to waste time ...

   Here is the reasoning why I proposed that the last 1 meter of ASI from 1m average thickness would melt to 0m faster than from 2m to 1m average thickness:
    -- As we lose the older thicker MYI, the remaining ice has higher percentage of younger, and thus saltier and easier to melt FYI.  Everybody seems to agree on that.

e.g. As interstitial noted at
https://forum.arctic-sea-ice.net/index.php/topic,2709.msg201895.html#msg201895
       Thinner ice, presumably with higher portion of First year Ice...
"has pockets with high salt concentrations in it. Some of the pockets even most may not of frozen solid.
   ...When the temperature climbs above -21C the pockets of high salt concentration melt first. The temperature is still too low to melt the pure ice.
   ... This is how multiyear ice is formed each freeze and thaw cycle of salty water can more and more salts out until it is pure ice with no salts. That makes the multiyear ice fresher and more melt resistant."

   -- But here is the main reason - the Thorndike (1975?) chart showing the differential rate at which ice of different thicknesses increases thickness, that Chris Reynolds posted to explain the Slow Transition hypothesis.  To me it says that unless there is some hysteresis effect, then that curve in reverse shows that thin ice also melts MUCH faster for the same amount of heat input.  For a given amount of heating energy, e.g. melting degree days in summer, more ice is lost per unit of energy in summer by thin vs. thick ice, just as more ice is gained by thinner ice for the same amount of freezing degree days during the winter.

      Here is the Thorndike chart

(And you know its good because it is Neven's account icon!)

     Here is my reversed version, with zoom into the last 2 meters.


     Seems to me that the Thorndike chart, when reversed, shows the amount of ice lost for the same amount of heat added to ice of different thicknesses.  Just as the original chart shows the amount of ice gained for the same amount of heat lost from ice of different thicknesses. 

     Thus, I am using Chris Reynolds' Slow Transition evidence to reach an opposite conclusion.

     This is a simple case of Teslacle's Deviant ("What comes in, must go out") to Fudd's First Law of Opposition ("If you push something hard enough, it will fall over") -- for you Firesign Theatre fans.  Seriously though, as a thermodynamic equation, what works in one direction should work in the reverse unless there is some hysteric effect at work.  (e.g. Teslacle was right!  This could be Vulvaire's Correlate to Teslacle - "What went out, comes back in.")

     Another chart adapted from an ASIF post by Jim Hunt
https://forum.arctic-sea-ice.net/index.php/topic,2709.msg201631.html#msg201631
shows the same phenomenon. I didn't reverse this one, but you can do that in your head.

   
     The only argument against a quicker final meter melt notion is that the because the CAB is at higher latitude, the melting process will stall as the Arctic ice melt reaches the high latitude end game.  And I might buy that idea if humanity was intelligent enough to stop pumping greenhouse gases into the atmosphere at an increasing rate, but not seeing evidence that we will, one can only suppose that warming will continue, and in fact that the rate of warming is increasing.

     I admit that gerontocrat's open water chart (up thread at https://forum.arctic-sea-ice.net/index.php/topic,2348.msg235525.html#msg235525) requires a huge rate increase in CAB September open water to have a BOE anytime soon.

      But the cumulative evidence argues that that is indeed what will happen.  While gerontocrat's CAB volume trend chart shows it reaches zero a few years later (ca. 2040?) than the whole-Arctic Wipneus volume chart (2032), it is not that much later.  That suggests that the CAB does not have enough extra resistance against melt to combat the inexorable warming and Arctic amplification underway. 

   As Tor Bejnar noted at
https://forum.arctic-sea-ice.net/index.php/topic,933.msg113144.html#msg113144
"I have also long considered the 'quick' loss of summer ice in the non-CAB regions over the past 30 years (e.g., the Beaufort going, in August, from 2/5th coverage to none between 2013 and 2016) not to be predictive of how fast CAB ice will be lost.  I think this discussion of bathymetry adds some geophysical creds to Chris's theses.  This doesn't mean, however, that I'm 'now' convinced Chris is right.  I think other issues like CO2-equivalent, mobility and storminess (emphasis added GK) may well 'over' compensate for the bathymetry-related suppression of warm water currents remaining near the ocean surface."

     As Bruce noted at
https://forum.arctic-sea-ice.net/index.php/topic,778.msg32178.html#msg32178
"Chris, I don't see any reason for the rate of summer melt increase to flatline, slow down, or even be linear. As the ice thins, the surface/volume ratio increases, which should increase the rate of melt. The thick MYI held off major assaults in 2017 and 2012, but that ice is nearly gone. What we have now is this "mesh ice" that spreads out as the edges melt (which, though it is a negative feedback (because it keeps more of the ocean covered with ice), is a short-lived one). That spreading increases the surface (both top and bottom) that can melt."

    In a second instance of using Chris Reynolds' evidence to reach an opposite conclusion, I will reinterpret a chart he posted at at https://forum.arctic-sea-ice.net/index.php/topic,933.0.html


   Read his post to see how he uses that to argue for the slow transition.  To me it shows that  September ASI volume hits zero ca. 2027, even earlier than the Wipneus chart.

   As for the hiatus, I think we've beat that to death.  I'll just repeat that 10 yearly data points is simply not long enough to make statistically valid conclusions for data with high interannual variability.  I will go out on a limb and bet that the 2012 minimum volume record has a 50% chance of being replaced in 2020, likely won't last beyond September 2021, and almost certainly won't last  beyond Sept. 2022. 

    That said by the guy who expected the October slow refreeze to continue based on GFS forecast showing continued high Arctic temperature anomalies over the last 10 days, when just the opposite happened.  I guess I was confusing the tail and the dog - my new guess is that the air temp. anomalies were high because the water transitioning to ice was giving off heat to warm the air above it. 



23
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: October 12, 2019, 06:33:47 AM »
All good points philopek, but here is an alternate view:

1) If the 80N+ circle is so much less susceptible to melt then why does that straight line downward trend in ASI volume give such a good fit, with 2019 exactly on target?
https://forum.arctic-sea-ice.net/index.php/topic,119.msg232085.html#msg232085 
        If the remaining most northerly areas are going to decline at a slower rate then that effect bettter kick in soon, because the straight line September minimum volume trend hits zero in 2032, and the August and October volumes only trail September by a few years.  If the 80N+ CAB ice is to be a long term survivor, I would expect that straight line trend to be bending upward by now.  But so far at least, the data do not indicate a rate change in volume decline.
   Similarly, there is no apparent rate change to justify other than a continued straight line trend in the September monthly average volume as charted by Jim Hunt  https://forum.arctic-sea-ice.net/index.php/topic,119.msg232040.html#msg232040

2)  Yes, water temperatures are lower in the icey CAB vs. peripheral seas, but those peripheral sea water temperature anomalies are large and encroaching at an unprecedented rate (as far as I know), e.g. https://forum.arctic-sea-ice.net/index.php/topic,2888.msg232462.html#msg232462
    And with declines in ice coverage of the peripheral seas, the effect of albedo decline to warm surface water during the brief summer edges ever closer to the North Pole.

3)  Observations of jet stream weakening and unusual if not freakish warm fronts crossing the North Pole do not bode well for the future of Arctic thermal isolation.  I confess to not understanding the details of Sark's analysis, e.g.  https://forum.arctic-sea-ice.net/index.php/topic,2692.msg232323.html#msg232323 but his scenario seems include loss of Arctic thermal isolation, and thus even greater polar amplification of warming.  Altered, equable weather patterns could also lead to increased ocean heat transport into the Arctic, which seems to already be happening.  What I understand better is the analysis of Jennifer Francis et al. that Arctic air spillage over my head in eastern North America appears to be increasing.  Which bolsters Sark's view in that if cold air is spilling out of the Arctic, then warmer air from the south must be migrating in to take its place.
     And the Arctic is of course part of the bigger picture.  CO2 & CH4 and other GHG emissions, levels in the atmosphere, and surface warming all continue to increase at essentially the RCP8.5 trajectory.  If the global system temperature was static, then the factors working against melt at 80+N might show up in the ice volume data.  But the global heat reservoir continues to increase, and at an increasing rate.  And the vast majority of that heat ends up in the ocean surface layer, where it can be carried to the high Arctic. 

4) As for average ice age, the Wipneus images at  https://forum.arctic-sea-ice.net/index.php/topic,119.msg232086.html#msg232086
https://forum.arctic-sea-ice.net/index.php/topic,119.msg232040.html#msg232040 show that the CAB ice fortress isn't what it used to be, i.e. it is no longer composed of thick, melt-resistant multi-year ice.  I suspect that the reduction of ice quality and "communal integrity" does not get enough attention.  That may be the factor that tips the balance to overcome lesser insolation at the North Pole. 

     So contrary to a long asymptotic stabilization, I can see just the opposite happening -- an accelerated chaotic ASI system breakdown.  With thinner fractured fresher ice replacing the previous thicker saltier MYI, loss of the Beaufort gyre nursery to replace MYI, currents and wind patterns to which the CAB was previously resistant may be able to cause accelerated CAB pack rotation.  That increased mobility could greatly accelerate export to lower latitude melt zones or out of the Arctic entirely through the Fram Strait.  And now the Nares may be a smaller secondary doorway that also allows greater ice pack mobility. Continued Arctic albedo decline moving northward.  Warm humid air fronts reaching the NP.  Continued Atlantification and Pacification of the Arctic Ocean with escalated SST moving closer to the NP.   

    If this view of the situation is correct, then we could be close to a systemic breakdown of the ASI, or at least a continuation of current trend despite higher latitude for the remaining ice.  We may get insight soon enough - if the the straight-line trend continues, that suggests that the 2012 minimum Sept. volume record has a > 50% chance of being superseded in the next two years.

     There are people much smarter than me who study this for entire careers and their understanding as shown in the IPCC reports etc. does not call for such radical change in the next 13 years. With my superficial understanding, I don't hold too much faith in my own opinion.  I may be spinning a few facts into conceptual storytelling. I really would love to be wrong.

    But I keep coming back to that linear ASI volume graph.  Until I see that trend change, my gut says trust the observations.

     

 

24
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: October 09, 2019, 03:57:32 PM »
     Thanks Stephan.  A zero Arctic sea ice volume date for September, and shortly thereafter for August and October has been on my radar for a long time from the Wipneus and your earlier graphs. 
 
      But zero ASI volume-in-July estimates of 2034 (linear) or 2038 (log) are shocking to even my jaded eyes.  Yikes.  The albedo impact of losing ice coverage in July is much greater than August and very much greater than September.  Actually, the whole situation is shocking, but we just get used to the evolving catastrophic trends as a new abnormal.  If that zero Arctic sea ice estimate in July date is anywhere near accurate then we are in big trouble sooner than previously realized.  Remember, you can't have Extent or Area without Volume, so 0 Vol in 2034/2038 also = 0 Ext. 

     FWIW, the September 2019 IPCC cryosphere report shows Extent becoming asymptotic at about 10% of the 2000 level around 2070. 
https://report.ipcc.ch/srocc/pdf/SROCC_FinalDraft_FullReport.pdf
     
     Given the length and detail of the IPCC cryosphere report, there is a surprisingly brief discussion of Arctic sea ice trends.  ASIF is a better source than IPCC! (seriously). After a quick search, I found nothing in the IPCC report about ASI volume projections.  Figure 3.3 on page 3-13 is the closest information.  It charts ASI Extent under the RCP scenarios.  In those projections, even the RCP8.5 scenario retains 10% September Extent for 2070-2100. 

      The scientists who donate their hard work to IPCC reports are the experts and I feel like an ungrateful flea telling the dog what to do in critiquing their work.  But my small fevered brain is unable to reconcile the trends charted by Wipneus and Stephan, or that I can see for myself in the data from PIOMAS, with the IPCC statements shown below from page 3-25.  To be blunt, I suspect that the IPCC is under-estimating the severity of the ASI trends.  If that were in fact the case, it would almost certainly be due to the political (in addition to scientific) consensus required before IPCC reports are released.  But let me not digress into conspiracy theory.  Here is the gist of what the IPCC Cryosphere report has to say about the expected future ASI:

      "There is a large spread in the timing of when the Arctic may become ice free in the summer, and for how long during the season (Massonnet et al., 2012; Stroeve et al., 2012a; Overland and Wang, 2013) as a result of natural climate variability (Notz, 2015; Swart et al., 2015b; Screen and Deser, 2019), scenario uncertainty (Stroeve et al., 2012a; Liu et al., 2013), and model uncertainties related to sea ice dynamics (Rampal et al., 2011; Tandon et al., 2018) and thermodynamics (Massonnet et al., 2018). Internal climate variability results in an uncertainty of approximately 20 years in the timing of seasonally ice-free conditions (Notz, 2015; Jahn, 2018), but the clear link between summer sea ice extent and cumulative CO2 emissions provide a basis for when consistent ice-free conditions may be expected. For stabilized global warming of 1.5°C, sea ice in September is likely to be present at end of century with an approximately 1% chance of individual ice-free years (emphasis mine) (Notz and Stroeve, 2016; Sanderson et al., 2017; Jahn, 2018; Sigmond et al., 2018); after 10 years of stabilized warming at a 2°C increase, more frequent occurrence of an ice-free summer Arctic is expected (around 10-35%) (Mahlstein and Knutti, 2012; Jahn et al., 2016; Notz and Stroeve, 2016)."

    They do say elsewhere in the report that CMIP5 models have relatively poor ability to recreate Arctic sea ice behavior.  The new generation of CMIP6 models are coming out and have improved capabilities.  It will be interesting to see what they have to say about ASI projections.  So far the only statements I have seen on output from the few CMIP6 model results being reported is that they (i.e. the multiple new component models of the new CMIP6 set) are consistently showing greater sensitivity of global surface temperature to rising CO2 levels than the CMIP5 estimates. 

       None of this bodes well for the ASI, or for human civilization unless we finally take heed and respond to the crisis with the intensity and commitment it requires.  Make your support for any politician explicitly contingent on their climate policy.  Talk about it even if you annoy people by doing so.  Vote climate as if your life depended on it.  Because it does.

25
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 09, 2019, 11:21:43 PM »
      And since I am pontificating on statistics, here are some take away messages from the recent graphical posts by Oren, binntho, Archimid and El Cid (and thanks to all).

RE binntho's Extent and Area straight line trend
https://forum.arctic-sea-ice.net/index.php/topic,2348.msg227604.html#msg227604
     While it certainly looks like a significant downward trend, you can't say the slope is different from zero without doing the stats.  It probably is, but your use of the visual assessment method is no more valid than it is for the folks arguing that the process has stalled because it looks that way in the last 10-13 years (again I am shameless, the same applies to me too, my sinful nature was noted in previous post.  We are all fallen creatures.)

RE Oren's CAB volume trend and thickness graph
https://forum.arctic-sea-ice.net/index.php/topic,2348.msg227570.html#msg227570
    That's almost the chart I was hoping for, but it would be even better with a straight line regression trendline, tested for difference from zero, and then extended out 20 years to 2040.  FWIW, if you squint and draw a straight line through the CAB volume trend for Day 243, aka end of melt season, the slope of that line will indicate about 4 million km3 decline from 2000 to 2019, i.e. 19 years.  If that trend continues, then take another 4M km3 over next 19 years and it reaches zero in ca. 2038.  That's only a few years later than the Wipneus straight line projection of sea ice volume trend for the entire Arctic.

    The key characteristic about Oren's chart is that it is limited to ice volume in the CAB.  Thus, it presumably removes possible inflation of losses by peripheral seas that are melting out sooner than the CAB.  What started this phase of the discussion was the notion that future loss rate would decline because the CAB would be more resistant to melting.  I think the Oren chart refutes that. 

     I was surprised how strongly negative the CAB end-of-melt-season (i.e. annual minimum, day 243 data) volume is.  The CAB may look like it's been hanging on, but apparently that is the deceptive Extent curve at work.  The CAB has been rotting out from the inside.  As for the future, the presence of ice in the peripheral seas late into the summer might have reduced past losses in CAB.  Their presence has kept Arctic Ocean albedo high and almost certainly reduced pack rotation and transport out through the Farm Strait (and thanks to Tor for insight on importance of  export losses).  With less protection from ice in those peripheral seas as they melt out earlier in the year, the rate of CAB losses could markedly increase in the future. 

   Archimd's graph shows that CAB volume losses appear to already be increasing https://forum.arctic-sea-ice.net/index.php/topic,2348.msg227455.html#msg227455.

     In addition,  the wider amplitude of the fluctuations in El Cid's graph
https://forum.arctic-sea-ice.net/index.php/topic,2348.msg227470.html#msg227470 gives me a bit of the willies because one of the predictors for a nonlinear chaotic system reaching a tipping point is higher variability.  I may be misapplying that concept because max to min amplitude is not the same as variability between years, but I allow myself my own superstitions.

    But 2038 as the projected zero year for CAB sea ice volume is over a century earlier than binntho's trend extension showing Extent not reaching zero until 2187. How can that be?   Extent is not declining as fast as volume because the remaining volume is being contained in thinner and thinner ice, and thus the Extent does not decline as much as it would if thickness remained constant.  But as the thinnest ice contributing to Extent reaches zero thickness, it stops contributing to the Extent number.  In the end, the Extent curve and the Volume curves have to meet because zero volume provides zero ice for Extent.

    Which brings me back to Oren's thickness graph.  Total conjecture, but my guess is that once average thickness gets below 1 meter we will start to see the end-of-melt-season Extent curve start catching up with its parent Volume curve.  Ice melting comments elsewhere on ASIF point to the much lower melt resistance of thin vs thick ice.  Regardless of my conjecture, the Extent curve HAS to catch up to the Volume curve eventually.

    Stay tuned.  I think there are wild times ahead for ASI in the very near future because it is on the edge of the precipice.  It will be entertaining for those of us who like to watch numerical systems evolve.  Too bad it isn't just a horse race or some other innocuous event, but is instead the loss of a crucial component for meteorological and climatic stability on the only planet in the universe known to host self-aware, so-called "intelligent" life (actually any life, but I think we will soon see that microbes are just about as common as water).  As my brother, a conservative who bought into the climate hoax BS for a while, but who is too smart to stay ignorant, said when he came to see the big picture: "This story does not end well".

   

26
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 09, 2019, 11:12:32 PM »
    Folks - we don't need to go around the wheel again about whether the recent apparent flat lining in annual minimum Extent and Area is real or not. (I don't think anyone is arguing that volume has flat lined).  Yes it looks like the trend has flattened out in recent years, and maybe it has.  The point is that given the degree of inter-annual variability between individual data points (i.e. years), the paucity of data points does not provide support for the assertion of a change in long term trend with any acceptable degree of statistical certainty (i.e. less than 5% or even 20% chance of a Type I false assertion error). 

     That said, just drawing a straight line trend through the 1979-2018 Extent data that looks like it points down is not a statistically based conclusion either.  But just from an eyeball view I bet it is significant.  (I know, I know, the hypocrisy is astounding!)  I admit I didn't actually run the tests, I'm too lazy and not enough time to do so, but Tamino has already covered this ground with far more skill than I could.
   
    Tamino has addressed the parallel issue of the so-called pause in global surface temperature warming after the El Nino driven high value in 1998.  I think that controversy is exactly analogous to this discussion about a possible flattening of the ASI Extent trend.
https://tamino.wordpress.com/?s=pause

    One of the best of those blog articles also discuss the same phenomenon at play with ASI https://tamino.wordpress.com/2019/01/07/fooled-by-noise/

   Appearances can be deceiving with noisy data.  As for rolling the dice 13 times, I think that is a false analogy due to the multiple testing problem. Again, see Tamino.

   The ice doesn't care what any of us think it's doing anyway, so let's just wait and see.  But that takes years, and inquiring minds want to know now, so here is a pseudo-answer. 

   I will bet the price of a lifetime subscription to the ASIF that the average of the 2019-2021 ASI Extent, Area, and Volume will each be less than the average of their respective values in 2016-2018.  Even with a statistically significant downward long-term trend, short term noise could lose that bet for me, but I don't think so.  I think too much damage has already been done, with more on the way. I agree with others who have noted that the remaining ice "doesn't look good".

   

27
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 08, 2019, 06:53:57 PM »
     Thanks El Cid and Archimid.  What I want to see is annual minimum volume (not loss from max, though that too is interesting) with straight line trend extended out 20 years.  (I know, extending trendlines past data range is fraught with potential error, but less so for straight line and certainly worth looking at.)

      To harp further on the Wipneus annual volume graphs (they are not written on a stone tablet from Mt. Sinai, but are worth attention as predictors IMHO):

1.  The annual minimum graph is lowest single day volume.   The Wipneus average volume chart for all the months shows average monthly volume, not single day min. for each month.
(also at https://sites.google.com/site/arctischepinguin/home/piomas
       For September the volume is nearly flat across the month, so the average monthly value is  almost the same as lowest single day annual minimum.  Thus, going below 1M km3 could be a multi-day event, not just a single day.   

2.  But the day after refreeze begins, some idiot will say the ASI is recovering.  The all-months volume graph shows August and October reaching the September value about 3 years later.
 Thus (combining this with the straight line graph for annual minimum), August and October could reach 50% chance of going below 1M km3  by around 2035, and 84% chance by 2039.  Open water in September won't change ocean water heating much, (and may even allow faster cooling) because solar radiation is so low after August 15.  But having the average August volume below 1M km3 would be a much bigger effect on insolation and SST, at least for the first half of August.
   {Wipneus - if your'e listening, can we have the all-months graph with straight line trends?}

3.  Torturing the data a little more shows that July and November track behind September by about 12 (Nov.) and 13 (July) years.  Adding 13 years to the Sept. values gives 50% of less than 1M km3 in JULY and November around 2045, and 84% chance around 2049.  Now that really gets us into hot water.  Literally, at least in comparison to pre-warming Arctic SST.  There is plenty of sunlight in the Arctic in July at a pretty decent impingement angle for solar warming.

4.  Extending my ignorance one more step, there is already talk that more open water in fall is affecting winter weather patterns.  If so, then if/when the Arctic is essentially ice free (i.e. < 1M km3) in November, the effect on winter weather patterns would seem to be much stronger.  Even though polar air masses should be a warmer by then, having the North Pole send its cold air over me in eastern U.S. is not a happy thought.  I had pipes freeze last year that cost me serious $.  Ironic to pay a bill like that because of global warming. 

5.  More important is the effect that such swings (if in fact they increase with Arctic warming as per Jennifer Francis et al.) can have on agriculture and other sensitive systems.  When the jet stream pattern lands to the east or west of the eastern U.S., instead of pulling polar air down, it can pull tropical air much farther north than usual, giving a freakishly warm extended period in winter or spring.  This happened in 2012.  Apple budbreak is remarkably stable between years despite big swings between cold and warm winters and springs, varying within no more than +/- 7 days between years.  That was until 2012 when we not only broke the previous earliest budbreak record, we broke it by 3 WEEKS.  Absolutely unprecedented in records as far back as anyone had.  Then after the early start, the last frost occurred at a relatively normal time, by which time the buds were far advanced and thus much more susceptible to frost.  As a result, growers in New England, PA, NY, and esp. MI lost their crop.  And not for first time in recent years. 

     So all this ice volume number crunching eventually turns into effects on the food we eat and other tangibles.  That's why we should let our politicians know in no uncertain terms that no climate change mitigation policy = no money and no vote for them.  And annoy our family, friends, neighbors by harping on the climate crisis.  it took all of us to screw this up and it will take all of us to turn it around.  That requires it being a topic of regular conversation, not just the latest altered weather report by Trump.  (By the way, what gets lost in that fiasco is that his misreprensentation of the hurricane track could have lulled people on the U.S. east coast into thinking that the danger was not heading towards them when indeed it was.  Though by now I think even the red-hat gang knows not to put much credence in the factual reality of his ramblings.)


28
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 08, 2019, 07:21:13 AM »
      FWIW, the Wipneus linear PIOMAS volume trend chart at
https://sites.google.com/site/arctischepinguin/home/piomas
suggests that by 2029 any individual year would have a 50% chance, by 2032 an 84% chance, and by 2036 a 97.5% chance, of going below 1 million km3 by the end of melt season.

     Given the argument that last phase of CAB will be the toughest to melt out, it would be interesting to graph CAB minimum volume over the years (or is such a graph already posted here and I missed it?).  That eliminates the influence of the peripheral sea contributions that could inflate loss rate relative to rate when the remaining late season ice is limited to CAB.  But it would also remove the effect of that ice in those peripheral seas has provided to protect CAB ice from open water melting effect (I think, not too sure about that).  Therefore, CAB rate of loss could increase once it loses that surrounding ice earlier in the melt season.

     The argument that the final CAB ice is at higher latitude does not seem to completely apply because the end of season CAB ice is not centered around North Pole, but is centered at lower latitude of triangle between NP, northern Greenland and northern edge of CAA. 

     Way above my knowledge, but my gut says that reinforcing feedbacks of wave action, open water albedo decline, fractured ice, increased exposure of remaining ice to transport currents, winter cloudiness or other factors giving weaker refreeze seasons, increasing SST (and with it increasing chance of GAC), and of course the ever increasing GHG levels in the atmosphere and monotonic warming-- esp. as 2 year lag in currently bottomed-out solar cycle starts to push temperatures up starting around 2023 -- will take a toll on the ice.  And by the late 2020s ENSO cycle could be trending towards El Nino phase adding even more push to surface warming (though I have no idea how surface air temperature effects from ENSO relate to SST and impact on ASI.  But at least it gave me an excuse to use 3 acronyms in the space of 8 words).   The point is, all those feedbacks working together seem likely to be more than enough to overwhelm any increased resistance of the final CAB core to melt. 

     And I suspect that measurement errors introduced by higher percentage of "rotten ice" are inflating reported extent values and thus suppressing the more recent rate of decline.  The remaining CAB doesn't look like a resistant pack, just a bunch of aggregated chunks.  All pure conjecture of course.

   The NASA animation up thread shows the Pacific side of ASI being an overwintering stronghold of MYI before 2007, taking a big hit in 2007 but recovering, taking another big hit in 2012, but coming back a bit in 2013-2015, then taking a third big hit in 2016 and not coming back after that.  Of course 3 years may be too short to say it won't come back, but with the one way trend of lessening ASI I doubt it will.  The loss of the Beaufort nursery seems to be a functional system change with major impact.  The MYI chart updated next spring could bring dramatic news on the MYI story, showing the virtual extinction of the oldest categories.

   Extent is declining less rapidly than Volume, but eventually will have to catch up it as both get closer to zero for September minimum (because 0 Volume forces 0 Extent).  Given the difference in trends between Ext. and Vol., it is important to specify which is being referred by BOE, though I guess the "official" definition is Extent.  By the time Volume gets close to 1 million km3, Extent should have mostly caught up, though I can also imagine a future with almost all FYI that by end of melt season still has large Extent but is approaching zero thickness and thus zero volume. 

    Even though 2019 is falling into 3rd or maybe 4th place for Extent, it is a solid second place for volume and will likely finish only about 200 km3 and about 5% above 2012 (and slightly below the Wipneus straight line trend).   As for 2019 Extent minimum, it is not over until the fat lady sings, and while she is standing close to the exit, she is still on stage. Given high SST and recent/forecast weather, a late finish such as 2007 looks very possible.   

29
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 03, 2019, 09:33:24 PM »
Another look at what I would describe as a new floor which supports a minimum threshold that will prove difficult to breach but looking at ice age instead of volume.

Good discussion.  And nice chart of early March Arctic sea ice portions by age of ice SH.
The chart shows 1st-year ice percentage increased from ca. 38.3% in 1984 to 65.8% in 2018, which summarizes to an average gain of 0.8% per year.  If that rate continued for another 48 years then 1st-year ice would account for nearly 100% of early March Arctic sea ice. 

    My understanding is that in one melt season, about 2 meters of ice thickness is lost.  And that the average thickness of 1st-year ice is also about 2 meters. 

   So... once we get to ca. 100% 1st-year ice at start of the melt season in March, then that ice would be thin enough to all melt out by the end of what is now an average melt season.
 
    Of course, with current and accelerating warming of global average surface temperature, by 2067, i.e. 48 years from now, the typical melt season will be much warmer so the scenario i'm creating here may arrive by 2050.

  There would still be refreezing in winter.  But progressively less on average each year.  So that's another trend to throw into the blender.  With a lower starting volume each year, the year when all, or nearly all, the Arctic sea ice melts out by end of melt season gets even earlier.

   And I end up back with what I consider the simplest and most convincing predictor of when Arctic sea ice annual minimum.  That being the Wipneus graph showing linear trend of annual minimum volume reaching zero around 2030. 
https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd7.png?attachauth=ANoY7co-JT1jjQGvpGxNEvrl0OaSjsV--ZIsZkJxM9mAn3liTvPonGye-SIwYIoMrdz3WhCjzTF-7eO1y4xjVMqo4Mqe6Py4I4KqkaHO97Qm_F7_j-0wn7hmI_ipG2OPbsk-eONQXLct1Ze62owhGmvWbQvdKVz21eBmKeJaoqz_EeC_3JYndbm6NHkkBDxQHAohuZUi9NrYqBUZ105uBQF7giHXXIyLZiC9G_kb1PqxmVgYs8y-q-WkPdR-VoZitgO_CypQuuTS&attredirects=0

     So no need for my layers of speculation and assumptions, just look at the numbers as graphed by Wipneus!  Also interesting to note that 2019 September minimum volume is going to land just about exactly on the linear trend in the Wipneus graph. 

30
Arctic sea ice / Re: Basic questions about melting physics
« on: August 31, 2019, 08:06:09 PM »
  The Arctic sea ice minimum has not decreased recently.  If you refuse to see that from the data, there is nothing more that I can say.

KK - depends on what you mean by "recently."  Given the internal variability of the system, a 7-year or 10-year window (i.e. since 2012, 2008) is too short to draw conclusions.  To protect against cherry picking and our innate human tendency for "pattern matching" where there is none, a longer interval of at least 20 years is required. 

     The 20-year downward trend in annual minimum Arctic sea ice volume appears to be much larger than year-to-year variation, and thus appears to be statistically significant.  Maybe somebody with more time and skill will run the stats on 1998-2018 annual min. volume data.  Moreover, 2019 is likely to end up with less the 4M km3, and thus land right on and thus reinforce the PIOMAS trend shown at
http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAprSepCurrent.png

    I think focusing so much on Extent leads us to false conclusions on both the high and low side.  2012 was bad for volume, but not nearly as extreme as it was for Extent.  To a substantial degree, Extent reflects temporary wind and current conditions, not the true status of the Arctic sea ice.  By focusing on Extent we can under-represent the cumulative progressive effects on overall condition of the ice. 

     The ice year this year has looked weaker more fractured than in past years.  A subjective measure to be sure, but not to be fully discounted either.  It will be interesting to see how the MYI numbers look after the 2019 melt season.  My guess is that they took another downward hit such that we are getting very close to only 1st and 2nd year ice that is more vulnerable than the tough old 5- and even 10-year old ice of the recent past.  The final phase of decline in ASI Extent is slowed by the much more rapid regrowth of 1st year ice.  But the flip side of that is that 1st year ice also melts out faster.   In retrospect, the functional loss of the Beaufort Sea ice nursery may be seen as a crucial event marking the beginning of the end of ASI in Aug-Sept.   I suspect with only 1st-year ice to get rid of at the start of future melt seasons, it won't last much beyond July 31.

     That's how it looks to me anyway.  No formal training in Arctic or ice, just a little experience analyzing numbers and interpreting science added to lurking in the ASIF.  Thanks to those who provide interesting info and speculation to ASIF.  Esp. thanks to Neven, Gero, JCG, uniquorn, Alphabet and others. Less gratitude for those who engage in extended ego-defensive debates.  To those folks I say, let others disagree with you and get over it.  Nobody else cares if somebody insults you.  Now you can disagree with me! 

31
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: August 17, 2019, 03:53:39 PM »
Is there anything about 2019 that is exceptional? If I understand, 2012 was exceptional because of a big cyclone in the Arctic (am I right)? Is 2019 just a near "normal" year?

     Seems to me that 2019 stands out for the overall poor quality of the ice (thickness, concentration).  Extent and Area do not necessarily reflect that poor condition  so even though it seems unlikely that 2019 will set new low Extent record, it represents another step down the path of arctic Sea Ice degradation, and all that that implies for the climate system as a whole. 

    One aspect the current situation that stands out to me is that the largest chuck of highest concentration CAB ice is on the Atlantic edge.  Very doubtful it will happen in the dwindling melt season, but a cyclone to export that chunk out of the CAB would make a big dent in the Extent/Area/Volume stats.  Though it probably won't happen, just the fact that it could is ominous.  And that IMO is the ASI headline for 2019 -- the ice is in worse shape and more vulnerable than ever. 
 
   As somebody commented above, this degraded state is occurring at/near minimum of a weak solar cycle.  Our friendly star is remarkably stable but the slight variation in energy received from the sun across solar cycle can nudge annual average global surface temperature up and down by ca. 0.1C.  So with ASI in this shape in 2019, what happens at peak of next cycle (albeit also expected to be relatively weak amplitude cycle relative to past 100 years)?  And of course with GHG emissions roaring along, and 93% of the extra retained energy going into the ocean waters, add that to next solar peak in 5-6 years and 2012's freak low Extent/Volume could start to look like the good old days when there were still millions of km2 MYI sea ice that carried over between years.

   So I guess the 2019 headline could be the beginning of the end for the ASI functioning over the last 12,000 years as a climatic anchor and stabilizer during the Holocene period.  That's the period during which so-called  "wise apes", aka Homo sapiens, learned how to do things like agriculture, science, literature and all the rest.  All just my lurker opinion of course.

     Climate sanity should be a requirement for any policy and politician to even be considered.  As the World Bank put it in back in 2012 (before the last 7 years of sooner/more severe climate study results) - the continuity of an "organized global community" depends on it.  I confess that I find it numerically fascinating to learn about the complex interactions of the ASI as it falls apart.  So a preliminary thanks to Neven, gerontocrat and others for hosting this soiree again this year.  But I don't want to see what "disorganized" global community looks like.  It would be nice if there was no reason to enjoy this forum.     


32
Arctic sea ice / Re: 2019 vs 2012
« on: August 14, 2019, 07:26:01 AM »
Post 2 of 2





The 2019 average index calculated by current melt season anomalies is marked with * and is shaded green.  The projected 2019 minimum Extent, Area, Volume, and Thickness values based on current melt season anomalies appear to less reliable predictors than the 2011-2018 average remaining losses.  The average ratio for based on the 2019 melt season anomaly estimates is included in the table to show relative position, but to avoid assigning two ordinal ranks to a single year, only the 2019 minimums based on 2011-2018 average remaining losses are assigned a rank vs. other years.  Likewise, the color coding for 1st, 2nd, etc. lowest values does not include the 2019 melt season anomaly values.

EDIT -- Dang part 2.  Away from computer and can,t fix right now.  Forgot to edit the yellow shaded 2019 values based on 2011-2018 average remaining losses in table below.  Extent ratio should be 1.14 and Area ratio should 1.17.  COMBINED AVERAGE stayed at 1.08. 


The index value for each year is based on its average of ratios to the minimum value observed in 1979-2019 for each measure, not by the average ordinal ranking.

Observations/Speculation: 
-- 2012 stands alone as the lowest overall with 1st place ordinal rankings for all four measures.  (Technically, 2019 minimum thickness was lower, but only by insignificant margin.) 

-- 2019 is second to lowest, with one 1st, and three 2nd place rankings.  The estimated 2019 minimums for Extent and Area are substantially larger than for 2012.  The 2019 and 2012 minimums for Volume and Thickness are similar.
      The *2019 minimum Extent, Volume, and Thickness estimates based on the current season anomaly are lower than the estimate based on 2011-2018 average losses from latest observation date to minimum.  But the Area estimate is higher.  While 2019 still finishes second to 2012 for the average ratio, the gap is much narrower. 

-- 2016 and 2011 are close to each other for 3nd lowest overall ranking, followed by 2010 and 2017 in a tie for 4th place. 

-- The sequential rankings of 2010 (#5), 2011 (#4), and 2012 (#1) suggest that the 2012 minimum record may have been the culmination of a three year sequence of predisposing bad melt years vs. being entirely due to conditions in 2012. 
 
-- Except for 2007, there is a high degree of congruence between the 2D measures (Extent, Area) and the 3D measures (Volume, Thickness). 

-- Nine of the 10 lowest ranking years have been in the last decade.  All of the top ten ranks, except 2007 at #9, have occurred in 2010-2019.  At rank #12, 2014 is the only year in the most recent decade to not be in the top ten for lowest index overall value. 

33
Arctic sea ice / Re: 2019 vs 2012
« on: August 14, 2019, 07:20:43 AM »
Post 1 of 2
     As per request I added an alternate version of the 2019 projected minimum based on extending the melt season to date anomaly vs. 2011-2018 average.  Thus if 2019 reduction in that measure to date was 5% higher than in 2011-2018, then the remaining projected losses to minimum would also be 5% higher instead of using the 2011-2018 average losses from latest observation date to annual minimum.









FWIW - August  12,  2019 has more ice on the Russian side which is surprising with the persistent high temperatures in coastal Siberia earlier this summer.  But 2019 has less ice in core of what used vto the MYI triangular fortress from norther Greenland  to North Pole and Down to Ellesmere Island.  Even though 2019 does not look to break the 2012 records for Extent and Area, it seems that the condition of the CAB is substantially weaker.  Also the high concentration/low spread CAB ice in 2019 is perched closer to the Fram Strait exit ramp.  I guess too late this year for it to get shuttled out of the Arctic and who knows where that ice will be next June.   But that location seems to be more bad news for ASI.



EDIT -- Dang - forgot to update 2019 projected min Extent and Areas based on 2011-2018 remaining losses in the tables.  Can't fix right now, away from computer.  Values in text section above tables are the correct ones.  The yellow shaded Extent in table should be 3.80 & 114%.  Yellow shaded AREA should 2.60 & 117%.
   Thus, since August 4 Extent got closer to 2012, but Area fell farther behind.


 







34
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: August 06, 2019, 08:53:47 PM »
X2 curvilinear regression.  R2 = 99.99% 
"1985" = midyear of 1979-1988, etc.

Year          Model estimate of Arctic Sea Ice volume at September minimum.
1985   21.41
1995   19.10
2005   15.34
2015   10.14
2025   3.49
2029   0.42
2030   "-0.37"

Conclusion:  If current volume loss trend continues, then around 2030-32, the September minimum will have virtually no Arctic Sea Ice.  Thus, all ice in following spring will be FYI from preceding winter.

But a regression curve extended beyond the data range can give overly aggressive prediction for rate of change.  A straight line regression has fewer assumptions, is more conservative and robust, Occams Razor etc.  Wipneus' straight line trend shows ASI volume hitting zero in 2032.

https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd7.png?attachauth=ANoY7crKtav-HYAq4lRVrck3FefppueqqYumZJyyPRWqKeDnVn1i8vijnas0L9wGuj90u1IgAAvG2UeObcryXJ77z5qU9jM1uHAoHO1XyoMAE8O49bSCo6hk-I7e-Z9KtLVBcMeJ_CBthasCWK-XUOGsyZEHNPREv6-IYzu2jSl9DWNUa2dqU71ccpWI5fz9YjX1PLecXkAIY2goroSLvb6G3JYTZ8hN837VDsLhctORifdxsAQxnjD8wAJ-C8ENPMFbXVsgh03e&attredirects=0

(Requires second click to download graph)

    The Wipneus graph shows 2019 being just about matching the midline estimate, slightly higher  than 2012.  By 2020 the midline estimate matches 2012, then trend reaches zero in 2032.  Lots of variation around the midline estimate of course, but seeing 2019 land right about where projected lends credence to regression validity and to the idea that very soon every year is likely to have less ice at minimum than 2012.   

Curved regression applied to Thickness shows zero at 2033. 
Extent curved regression does not reach zero until 2070. 
But no volume = no ice for Extent.

Thus on current trajectory in about 11-13 years (2030-32) human-caused climate change may have so altered the Arctic Sea Ice as to cause fundamental functional change to a keystone physical component of the Earth's climate system.

Meanwhile -- pundits, politicians and economists discuss the fine points of other issues as if they matter more than the planetary life support system.  Other issues are important, but human civilization relies on a supportive climate system, so not destroying that must take precedence.

35
Arctic sea ice / Re: 2019 vs 2012
« on: August 06, 2019, 09:59:09 AM »
Arctic Sea Ice Scorecard
Post 3 of 3.



Observations/Speculation: 
-- 2012 stands alone as the lowest overall with 1st place ordinal rankings for all four measures.  (Technically, 2019 minimum thickness was lower, but only by insignificant margin.) 
The index value for each year is based on its average of ratios to the minimum value observed in 1979-2019 for each measure, not by the average ordinal ranking.

-- 2019 is second to lowest, with one 1st, and three 2nd place rankings.  The estimated 2019 minimums for Extent and Area are substantially larger than for 2012.  The 2019 and 2012 minimums for Volume and Thickness are similar. 

-- 2016 and 2011 are close to each other for 3nd lowest overall ranking, followed by 2010 and 2017 in a virtual tie for 4th place. 

-- Heading into 2012, the prior two years -- 2010 and 2011  -- were ranked #2 and #1 (now 5 and 4), which suggests that the 2012 minimum records may have been the culmination of a three year sequence of predisposing bad melt years vs. being entirely due to conditions in 2012. 
 
-- Except for 2007, there is a high degree of congruence between the 2D measures (Extent, Area) and the the 3D measures (Volume, Thickness). 

-- Nine of the 10 lowest ranking years have been in the last decade (all except 2007 at #9).



This report is not sanctioned by the National Snow and Ice Date Center, the Polar Science Center, or any other institution.  This report is a personal effort to make the situation of Arctic sea ice decline easier to understand as an indicator for the rapidly progressing and accelerating planetary climate crisis. 

Perspectives:


---------------------

The following image shows Arctic albedo loss across 7 years. 
But it is outdated now because it only includes 3 of the top ten smallest minimum Extent years.  Current albedo reductions relative to a 2000-2004 baseline must be much higher.




36
Arctic sea ice / Re: 2019 vs 2012
« on: August 06, 2019, 09:07:50 AM »
Arctic Sea Ice Scorecard --  Volume and Thickness* values updated through July 31.
Post 2 of 3.
  (* There was an error in Thickness values in the first scorecard posted on July 26.  Thickness values corrected in this edition.)





37
Arctic sea ice / Re: 2019 vs 2012
« on: August 06, 2019, 09:01:21 AM »
    Arctic Sea Ice Scorecard updated for Extent and Area through August 4.
Part 1 of 3 posts. 
     Still using 2011-2018 average losses from current date to September minimum as baseline for predicting 2019 minimums. 
    Post by Klondike Kat indicated that season to date anomaly vs. average loss rate was not a good predictor for remainder of year losses.  KK data also indicated that due to variability between years, using a more recent but smaller set of years would not give a reliable average.











38
Arctic sea ice / Re: The caa-greenland mega crack
« on: July 30, 2019, 08:39:26 PM »
"Sodium Flerovium"
   Could be a spell from Hogwarts to desalinate seawater.

39
Arctic sea ice / Re: The 2019 melting season
« on: July 30, 2019, 12:23:55 AM »

Shocking. Huge areas on the Pacific and Asian sides look increasingly vulnerable.

Not just the Pacific and Asian.  Am I the only one shocked by seeing less than 90% concentration in the heart of what used to be the MYI overwintering zone just north of Greenland and Ellesmere Island?   Is that as weird as I think it is?

40
Arctic sea ice / Re: The 2019 melting season
« on: July 29, 2019, 11:36:29 PM »
IMHO the one thing 2019 was missing to get real low
I have some issues with that wording because:
Why WAS missing, the melting season and it's outcome are not yet over
Why "to get real low" after all we ARE in fact LOWEST on record for quite some time now
and in total this year.
I suggest to wait another 30-40 days for such kind of verdict. Once 2019 should be behind 2012 so much that only a miracle could do a turnaround, your reasoning could become valid IMHO :D

Fair critique of my imprecise wording.  By "get real low" I meant "go lower than the 2012 record-breaking September minimum Extent." 

Part of the 2012 blowout was the Great Arctic Cyclone in August 2012 which I have always assumed was a big part of why 2012 was so much lower than all previous years.  Recent comments in ASIF have me questioning that somewhat, but it still seems like a major contributing factor.  Since it seems unlikely that there will be repeat of the 2012 GAC in 2019, that was a missing factor that could keep 2019 Extent from going lower than 2012. 

The point I was making was that with this week's:
1) widespread Arctic air temperature heat wave,
2) very warm SST anomaly forecast north of Greenland in what used to be the heart of the thickest overwintering MYI,
3) that photo post by subgeometer showing Beaufort destroying ice moving in from the CAB,
and
4) the Oren post on return of wind patterns that could move Atlantic-side ice out of the Arctic to melt in the Barents or Greenland seas
  --- something seemed to snap in place that wasn't there before.

Looking at Killian's stats on daily average losses required for Sept. 2019 minimum to end up below 2012, prior to today it seemed unlikely to get those losses because they are quite high and we are already on the downhill side for daily melt rate.

What snapped was, with #1-4 above, it might not require a GAC in 2019 to keep up with what happened in August 2012.  Those four factors (#1-4 above) acting in concert could provide a similar negative impact on remaining sea ice even without another GAC uin 2019. 

Just a notion, not a verdict.  Obviously we won't know until September.   But that's what we do here right?  -- Track what's going on, look at weather forecasts, speculate about how it all works, and guess at where it's going to end up (primarily for Sept. minimum but other markers too) based on current observations and our evolving understanding of driving factors and patterns.  It is a fascinating puzzle and process to watch. 

41
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 28, 2019, 05:45:06 AM »
Would anybody be able to tell me what the current consensus is on the degree of global dimming we currently have? My understanding was that it was somewhere between .8c and 1.2c but somebody in the 2019 melting thread said that it is now considered to be much lower than previously thought.

Charts from James Hansen and others indicate that aerosol blocking of incoming solar energy creates a negative forcing of about 0.5C.  Thus if we had current GHG levels without aerosols, global average surface temperature would be more like 1.65 C over 1850-1900 average (using NASA GISTEMP data) than the current 1.15 C.   So we are already doing inadvertent, ignorant geoengineering / solar energy management. 

42
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 04:08:00 AM »
Last of 3 posts (and a half dozen updates to fix glitches).
   Yearly average ratios across Extent-Area-Volume-Thickness
...and the winner (so far) is.... (but you already knew)

 
Observations/Speculation: 
   -- 2012 stands alone as the lowest overall with two 1st place and two 2nd place rankings among the four categories.
   -- 2019 is second to lowest, with two 1st, one 2nd, and one 3rd place rankings.  2019 would require a lot of catching up in Extent and Area in the remaining weeks of melt season to take 1st place away from 2012.
   -- 2016 and 2011 are close to each other for 3nd lowest overall ranking, followed by 2017 and 2010 in a virtual tie. 
   -- The sequential rankings of 2010 (#6), 2011 (#4), and 2012 (#1) suggest that the 2012 minimum record was the culmination of a three year sequence of predisposing bad melt years vs. being entirely due to conditions in 2012 alone.
   -- Volume rankings are closely correlated with Extent and Area.  Thickness rankings less so.
   -- Nine of the 10 lowest ranking years have been in the last decade (all except 2007 at #9). 

Definition of terms, caveats, top 20 rankings for each category, and a few other things in the full PDF. Including a still photo from great video of what ice looks like at the edge of the Extent line.
Figure 2.  Ice condition near edge of the Extent limit.  Photo taken at 75N, 150W on October 29, 2016.  Credit: “Waves propagating through Arctic sea ice.”  By IBWOvids. 





Lots of calcs involved and done in a hurry, so errors possible.  Corrections and suggestions appreciated.  Now that the spreadsheet is set up, occasional updates should be pretty easy if folks are interested.


43
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:55:56 AM »
4 more screenshots - Area, Concentration (opposite of Dispersion), Volume, Thickness


 




44
Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 03:41:39 AM »
Screenshots from
"Arctic Sea Ice Score Card: Extent, Area, Concentration, Volume, & Thickness - 2019 vs. 2012"
17-page PDF at http://204.197.0.54/MEmodel/NSIDC-PIOMAS2012vs2019-July26.pdf
(but that server is misbehaving 7/27/2019, should be fixed by Monday).





2012vs2019 NSIDC concentration images

45
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 14, 2019, 11:18:11 PM »
    IPCC is made of humans.  From what I understand the scientists (mostly unpaid for the extra work) give their best effort at corralling and summarizing vast amounts of information, then the politicians get to edit the language used to communicate it.  The IPCC reports are essential and immensely useful, imagine if we did NOT have them.  But they are imperfect. 

     Short report well worth reading --
"What Lies Beneath: The scientific understatement of climate risks"
   excerpt: 
    "What were lower-probability, higher-impact events are now becoming more likely. This is a particular concern with potential climatic “tipping points” — passing critical thresholds which result in step changes in the system — such as the polar ice sheets (and hence sea levels), and permafrost and other carbon stores, where the impacts of global warming are non-linear and difficult to model at present. Under-reporting on these issues contributes to the “failure of imagination” that is occurring today in our understanding of, and response to, climate change. If climate policymaking is to be soundly based, a reframing of scientific research within an existential risk-management framework is now urgently required. "

https://www.researchgate.net/profile/David_Spratt3/publication/324528571_What_Lies_Beneath_The_scientific_understatement_of_climate_risks/links/5ad2e4120f7e9b2859343e58/What-Lies-Beneath-The-scientific-understatement-of-climate-risks.pdf

46
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 11, 2019, 08:18:52 PM »
BOE-year: "aaaah, blue ocean" "oh, nothing happens, it just refreezes"
BOE-year+1: "oh, again blue ocean" and we will have some weird weather, but those are just 'incidents'
BOE-year+2: "that's weird, 3rd BOE in a row and too early" and weather patterns become unpredictable in northern hemisphere with lots of extreme weather and reality finally sinks in

 :) Yup, human adaptability is huge with both good and bad consequences.

    Wipneus monthly volume chart ...
 https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png?attachauth=ANoY7crjDWOoXxuYh--3XZJMMEyECWySrgq9Q6TOUN13dC9ljMI_ZkqhIWoNNcgTFYxBjLxvMe3STZLbt3k6bd0GwBpqzGkzohemPAA3GvfzG6SssxfZyFH-g31mVYUi2ry5mVuUDXgqskqLyP-DxntNev3GJXMUYPhCqQkciQp6wMWdg2ZwozcLhLTUP5cobWGW4oqexYFgcc5c_0LIY1S59DGxmZW-Fjn61fUNUVGaZPJ2bmTzGpCSJLsnGmLbSmB9feyuhBT_&attredirects=0

    ... shows that August (and October) only trail September by about 2 years.  Since September is pretty flat on the volume curve, it doesn't seem like it would take too many years for a BOE day in September to lead to a full month September BOE.  Then, with the usual annual variations adding a few years of noise, we might have a BOE for much of August.  And that would create some serious albedo change and create a new "melting momentum" that might not be polite enough to stop by the time we notice. 

     In recent interview Peter Wadhams threw out a concept I hadn't heard before.  With continued loss of ASI there could be a tipping point where polar jet stream doesn't just weaken and wobble, but just goes away completely.  I don't know if that is at all realistic, but if it did happen it would seem to be like Jennifer Francis thesis on steroids, with potential drastic changes in weather patterns, or just weather chaos until new patterns emerged.  I guess there's always a pattern, but if there was a complete loss of polar jet stream steering of weather systems that just seems like crazy town.

47
Arctic sea ice / Re: The 2019 melting season
« on: July 10, 2019, 03:16:41 PM »
One question about this graph on Karsten Haustein's website.
Does this mean the GFS model is underestimating temperatures, or is it the other way around?
See chart at https://forum.arctic-sea-ice.net/index.php/topic,2591.msg212351.html#msg212351

    Non-expert talking, but I've been tracking GFS prediction vs. GISTEMP finalized values for several years.  Looking at the chart and my monthly comparisons indicates that the chart is saying that for Jan, Feb, Mar and Apr the GFS forecast turned out to be lower than the subsequent GISTEMP observations (by 0.06 C averaged across those 4 months).  For May, the GFS forecast turned out to be slightly (0.01 C) above the reported GISTEMP observation. 
   
    June forecasts were running above verification until mid-June.  On June 12 NOAA switched to new FV3-GFS model that so far has been underestimating global surface temperature when compared to verification.

      As of July 10, based on observed GISTEMP for Jan-May, and GFS forecasts for June and July 1-17, the estimate for end of year 2019 average is ca. 1.17 C above 1850-1900.  2019 will be first or second place (85% chance) relative to all other years in 1880-2019 GISTEMP record.  2019 is near record warm with only moderate El Nino effect, and on downward side of solar cycle which has a real but smaller influence.

    Bottom line: The planet continues to warm.  IPCC projections are based on straight line 30-year average projection of  0.2 (+/- 0.1) C per decade.  But a closer look shows that the rate of increase is increasing, e.g. 2009-2019 (11 years to includes a full solar cycle) change in GISTEMP is 0.36 C per decade.  We will be lucky not to pass 1.5C by 2032.  God bless the folks who AFAIK mostly donate their time to create IPCC reports.  But any report that requires consensus of 1500 scientists and 200 governments is bound to be conservative.  If you think IPCC is alarmist, read https://www.researchgate.net/publication/324528571_What_Lies_Beneath_The_scientific_understatement_of_climate_risks
     

     OK, done preaching to the choir.  Not completely on topic for 2019 melting thread, but obviously related.  The energy that is melting the ASI is relentlessly increasing because of our choices.  Being aware means being alarmed, and better yet activated in pursuing solutions that are already available. 

48
Arctic sea ice / Re: 2019 vs 2012
« on: July 09, 2019, 09:55:06 PM »

From NSIDC archive of daily Arctic sea ice concentration images

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/images/2012/07_Jul/N_20120708_conc_v3.0.png
vs.
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/images/2019/07_Jul/N_20190708_conc_v3.0.png

FWIW - Some amateur opinions for consideration and feedback:
1) to my eye July 8 2019 ASI concentration looks more vulnerable than same date 2012.  The few areas where 2019 has more ice are doomed by Sept. anyway.

2) I don't think the extent and area metrics we use to compare between years fully reflect the degraded ice condition in 2019.  Volume has a better chance of reflecting actual situation, but of course it has its own issues.

3) There is still a lot of melt season weather left to go, and as reported in the forum, late July-August 2012 weather was conducive to melt.  While June 2019 was blistering, it remains to be seen what remainder of 2019 melt weather will be like, but it will be hard for 2019 to match late-season 2012.  So that's gives an edge to 2012 in terms of the Sept. minimum extent/area/volume.

4)  And 2012 had the Great Arctic Cyclone. I have to assume that an event of that impact is unlikely in 2019.  But 2019 may bring its own events -- perhaps a couple of less intense events will have cumulatively equal impact as the 2012 GAC.  A return of an Arctic dipole hinted at in the 10-12 day forecast yesterday is an example of hits 2019 could yet deliver to the weakened ice fortress.
   
 5) Of greatest importance -- 2019 includes 7 additional years of a) continued decline of anchoring multi-year sea ice, b) what appears to be qualitative functional changes in ocean heat incursion, c) increased ice pack mobility, d) polar vortex weakening, e) higher atmospheric CO2e, and f) higher global SAT -- by about 0.3C increase between 2012 to 2019.  That's a huge amount of extra energy in the surface layer of the climate system (not even counting the energy buried in the ocean, some of which could affect Arctic sea ice melting this year).  There is a lot of additional heat embedded in the Arctic and surrounding system in 2019 vs. 2012.
   
   6)  Because of #5, I think we really can't know how close to the cliff we are.  But we can be sure that we are getting closer to that cliff every subsequent year of not only persistent elevated GHG level, and not just year-on-year additions, but increases in the rate of increase of GHG loading. 
 
   7) So... 2019 vs. 2012?  A toss up for Sept minimum only because 2012 was such a blow out.  But on the current trajectory it's just a question of when, not if, cumulative progression will push the system below 2012 and make every year below 2012. 

  8) It's natural to focus on  landmarks like Sept. minimum extent/area/volume, but in case you missed it, see the 365-day running average extent the industrious and appreciated gerontocrat posted at https://forum.arctic-sea-ice.net/index.php/topic,2533.msg211770.html#msg211770.  And the even more dramatic 365-day running average volume posted at https://forum.arctic-sea-ice.net/index.php/topic,119.msg211798.html#msg211798.
     More than the ASI status on a single September day, those trends show the larger story of what we are doing to a critical part of our climate system. 

     The world needs the people informed by this forum to spread the news of this existential threat to family, friends, neighbors, colleagues, and politicians.  Please talk about it, that is the essential first step.       


49
Arctic sea ice / Re: The 2019 melting season
« on: July 06, 2019, 04:55:15 AM »
Even if 2019 does not end up below 2012, the SIPN estimates all hovering just above 4 million km2 are historically low

Walsh, J. E., W. L. Chapman, and F. Fetterer. 2015, updated 2016. Gridded monthly sea ice extent and concentration, 1850 onwards, Version 1.1. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media. http://dx.doi.org/10.7265/N5833PZ5.

As for the horse race with 2012, am I the only one thinking that most of the SiPN estimates, with average of 4.2 km2 extent at minimum, are too high?  Possibly because they are based on historical correlations that no longer apply to a new Arctic sea ice regime where all the ice older than 2 years may be virtually extinct by the end of 2019 (except for nooks and crannies in CAA).

   Perhaps I am overreacting to latest NSIDC Arctic sea ice concentration image.  To me it looks like a pile of slush that could be flushed out through the Fram Strait with the right combination of warmth, clear skies and a couple of storms.  It does not look like an ice pack with enough resistance to withstand the remaining 45% of melt season.


50
RE post #2751 about albedo in the 2019 Melt Season thread

Radiative Heating of an Ice‐free Arctic Ocean
Kristina Pistone Ian Eisenman V. Ramanathan
First published: 20 June 2019
https://doi.org/10.1029/2019GL082914

"During recent decades, there has been dramatic Arctic sea ice retreat. This has reduced the top‐of‐atmosphere albedo, adding more solar energy to the climate system. There is substantial uncertainty regarding how much ice retreat and associated solar heating will occur in the future. This is relevant to future climate projections, including the timescale for reaching global warming stabilization targets. Here we use satellite observations to estimate the amount of solar energy that would be added in the worst‐case scenario of a complete disappearance of Arctic sea ice throughout the sunlit part of the year. Assuming constant cloudiness, we calculate a global radiative heating of 0.71 W/m2 relative to the 1979 baseline state. This is equivalent to the effect of one trillion tons of CO2 emissions. These results suggest that the additional heating due to complete Arctic sea ice loss would hasten global warming by an estimated 25 years."

Trillion tons CO2, i.e. about 25 years of current annual global emissions.  That's just a theoretical benchmark number of course, we are a long way from Arctic being ice free all summer.  But every portion thereof adds another slice of warming energy. 

Same authors did an earlier, more practical study:
Observational determination of albedo decrease caused by vanishing Arctic sea ice
Kristina Pistone, Ian Eisenman1, and V. Ramanathan
322–3326 | PNAS | March 4, 2014 | vol. 111 | no. 9
www.pnas.org/cgi/doi/10.1073/pnas.1318201111


"The decline of Arctic sea ice has been documented in over 30 y of
satellite passive microwave observations. The resulting darkening
of the Arctic and its amplification of global warming was hypothesized
almost 50 y ago but has yet to be verified with direct
observations. This study uses satellite radiation budget measurements
along with satellite microwave sea ice data to document
the Arctic-wide decrease in planetary albedo and its amplifying
effect on the warming. The analysis reveals a striking relationship
between planetary albedo and sea ice cover, quantities inferred
from two independent satellite instruments. We find that the Arctic
planetary albedo has decreased from 0.52 to 0.48 between 1979
and 2011, corresponding to an additional 6.4 ± 0.9 W/m2 of solar
energy input into the Arctic Ocean region since 1979. Averaged
over the globe, this albedo decrease corresponds to a forcing that
is 25% as large as that due to the change in CO2 during this period,
considerably larger than expectations from models and other less
direct recent estimates. Changes in cloudiness appear to play
a negligible role in observed Arctic darkening, thus reducing
the possibility of Arctic cloud albedo feedbacks mitigating future
Arctic warming."

Note that study period ended in 2011.  After 2019 easy to think that 25% could be up to 30%.


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