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Messages - Glen Koehler

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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
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.   

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.

     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. 

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

    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! 

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.     

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.

-- 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. 

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.


Arctic sea ice / Re: 2019 vs 2012
« on: August 10, 2019, 07:59:49 PM »
Thanks Random, very interesting views

Arctic sea ice / Re: 2019 vs 2012
« on: August 07, 2019, 04:11:21 PM »
No analysis.  I simply used 2011-2018 because 8 years is enough to get a reasonably defined average.  And those are the most recent years, so the best we have to reflect any functional changes in the system.  I wanted 2012 in the mix because it happened once so it can, and likely will, happen again.  But by being mixed in with 7 other years, 2012 is only a partial influence.

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.

(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.

Arctic sea ice / Re: 2019 vs 2012
« on: August 06, 2019, 08:21:34 PM »
Right dnem. 
I used the 2011-2018 average reduction from latest observation date to the value at Sept. minimum Extent/Area/Volume/Thickness for those years and subtracted it from the value 2019 had on latest observation date.

Prior posts discussed idea of extending currently season anomaly above (or below, if that were the case) the 2011-2018 losses until the end of the melt season.  Thus, if 2019 losses were 5% greater than average losses from start of melt season to latest 2019 observation date, then the average 2011-2018 losses until minimum would be multiplied x 105%.

That seemded like a good idea until Klondike Kat showed an analysis that the anomaly above average melt rates in early season was NOT a good predictor of higher melt rates for remainder of season.  So I stuck with the original method.  That makes sense in that just because June was above average warmth/sunshine etc., that does not mean August will be too.  Just because a stock went up Tue. doesn't mean it will keep going up Wed, Thur, Fri.

But as is often discussed in the ASIF, "melting momentum" is a real thing.  Once ice gets preconditioned by strong melting forces, accelerated melt rate can continue for a long time afterward.

I am going to stick with the simple 2011-2018 average remaining losses as the most reliable predictor for remainder of current year (just my guess), and it is simple to understand.  But I can add a second 2019 estimated Sept. minimum value for Extent/Area/Volume/Thickness that pays heed to melting momentum.  I can do that by dividing the year to date 2019 losses for each measure by the 2011-2018 average for those dates to get the anomaly percentage for 2019 Ext/Ar/Vol/Thick losses up to current date.  Then use those anomaly percentages to multiply x the 2011-2018 average losses for remainder of year to create another estimate for 2019 that assumes continued ice loss anomaly.  I can add them to table without an ordinal number so as not to mess up the rankings by having two ordinal ranks for a single year.  But it's location in the table would show all that anybody wants to know -- how does 2019 compare to 2012 and other years.

Can't do it now, out of time.  But after August 14 which marked the end of GAC in 2012, another update comparing 2019 to 2012 and other years would be interesting and I can show estimates for 2019 minimums using both methods.

Sorry that the 2012 vs 2019 NSIDC conc. map posted so large.  First time I saved it, the size was normal, as is the 1980 vs 2012 Sept. min. image.  I don't know how to control size of the image when added to forum post.

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

-- 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. 



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.

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.)

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.

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.

Arctic sea ice / Re: The 2019 melting season
« on: July 30, 2019, 06:31:45 PM »
Climate Reanalyzer / GFS forecast for precipitable water shows low pressure system movement swiping from west to east (looking from North American side) just south of the North Pole on days 1-10.

  In addition, a low pressure system over NW Russia goes below the 980mb Category 1 hurricane pressure threshold at times but weakens and dissipates by the time it moves over to FJL/Barents Sea at end of the 10 day forecast.  If that all happens it would contribute to the air flow to move less than solid CAB ice towards Atlantic side and eventual export to melt in the Barents and Greenland seas.  Not a repeat of 2012 GAC by any stretch, but another potential contributing weather factor to move ice and possibly stir up water enough to bring up subsurface heat.

   As PETM said upthread, the destruction is interesting to watch, but this is getting scary. 
Yes, there will be overwintering ice from which to rebuild over what is likely going to be another wimpy (relative to pre-2015) Arctic winter.  But it will be thinner, less volume, younger and less melt resistant at start of 2020 melt season than in the past.  Nothing new in that I guess, it's been following that trajectory for decades now.  If more of the same can be called news, the news is that the progressive disruption of the Arctic sea ice, and interference with the roles it plays in the climate system, isn't turning around or slowing down.

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?

Arctic sea ice / Re: 2019 vs 2012
« on: July 30, 2019, 12:10:47 AM »
Consequently, melt to date is a poor indicator of additional melt.  Hence, assuming a continued melt rate through minimum is no better than assuming average melt.

Thanks Klondike.  I think I'll stick with using past average remaining losses from previous years and retract adding the complication of also showing estimates based on this year's anomaly vs. that average. 

Richard Rathbone comment about negative skill by using years from too far back in the average to estimate remaining losses from current date to minimum has me thinking why not just use most recent years as they must be the most relevant in a rapidly and monotonically evolving system.  So instead of 8 prior years, I might go down to the previous 5 years.  Should still be a large enough set to smooth out any single year outlier effect.  I don't really need a small standard deviation for the average.  I'm not doing probability distribution,  just a simple guess at final annual minimum based on average of remaining losses from current date to end of melt season in previous years.

I even thought of using just the most recent 3 years, but that would allow values from flukey conditions in a single year to have too much influence vs. having the average provide a good estimate of what is most likely to occur in the current year. 

I'm just guessing at all of this of course.  Not enough time or expertise to really suss out the best method, but open to suggestions.

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,
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. 

Arctic sea ice / Re: The 2019 melting season
« on: July 29, 2019, 03:06:47 PM »
oren, subgeometer - Thanks for info on transport.  IMHO the one thing 2019 was missing to get real low was continued Atlantic transport.  Now that it appears to be coming back, the 2012 record may be in reach even without a 2019 cyclone (which with so much open water and high SSTs seems like that also becomes more likely).  Those warm SSTs just north of Greenland are striking at the heart of the ASI fortress.  And seeing Beaufort melting ice as soon as it arrives from CAB is another piece (esp. when Beaufort used to be the nursery for MYI).  Killiian's required loss per day stats seemed hard to reach until reading all these recent posts.  The combination of these assaults looks like a multifaceted equivalent of the 2012 GAC.  Continued decline of MYI seems like a sure thing, leaving 2020 with little ice over 3 years old, most of it 2 or less, and much of it as less resistant 1st year ice.   

    As for new record min in 2019, still a ways to go.  But all the talk in May-July about 2019 ice looking weak seems to be taking effect.  Predictions based on past patterns may not hold because it seems likely that the 2019 fractured thin ice will behave differently as end of melt season nears than it did in past years with thicker more contiguous ice.   

Arctic sea ice / Re: 2019 vs 2012
« on: July 29, 2019, 02:29:03 PM »
Hi Richard - I chose 2011-2018 simply because those are the most recent years with enough years in the set  - 8 - to get a reasonably well defined (low StdDev) average.  Zero testing.  I did want the epic 2012 in the set.  I now think that it would be good to include 2010 in the recent avg because it was also a big loss year -- #6.

Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 11:37:59 PM »
If 2019 melt season to date has been above average, then why project the 2019 end of season as being just average rather than projecting it to be equally above average? Gerontocrat's post for today identifies extent loss for 2019 as 6.9% greater than average from the 2019 maximum. Would it not be more reasonable to use that same 6.9% greater than average loss for the rest of the year.
It is all projection and as they say in investing past performance is no guarantee of future performance but it would make more sense to base the projections on the current year than on an average of past years wouldn't it? There is some validity to the current year building momentum and to the current condition of ice compared to ice from what ice was on average over the past 8 years.

I third that idea.  Would be interesting to add to the 2011-2018 avg remaining losses to minimum for parallel projections.  Gets at the issue that Arctic behavior could be in new functional state such that even recent past averages are not the best or at least not the only reasonable expectation for current situation. 

This stuff is certainly interesting, I just wish it did not bring with it such dread.  Great to have community to collectively chew on tthe details and the scary prospects for my kids and all of of us.  Would be even more disturbing to watch this train wreck unfold alone, would be maddening actually. 

mini-speech (again) - I work in the natural sciences (ag & biology), and if people think that the general scientist community is fully aware of the pace and prospects of what's happening our spaceship Earth, my observation is that they would be wrong.  Heck even some of the people I do climate adaptation work with do not fully get the urgency.  The scientists and other smart people I interact with know the basic trajectories, but like like all of us, our  rains focus on the day to day issues.  Hard to save the world between breakfast and dinner.

 The climate crisis is so big that it is hard to react to in specific ways. But we have to take any steps we can to push a survival agenda.  In case it's news, we are heading for deep doo doo friends.

 I'm off topic for this thread and becoming a pain in the butt with yet another iteration of this speech.  Sorry, I just can't help preaching to the choir.  I just hope all us who visit the ASIF will become irritants even if it makes us irritating and predictable to our family, friends and our larger social network.   If not those of us who watch the unfolding epic changes in minute detail, then who else? Thanks for considering this request.  I will try to stick to the data hereafter -- for a while at least.

Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 05:55:32 PM »
Perhaps the value rather than the ranking is more relevant.

2D ratios = f(Ra, Re)
3D ratios = f(Rv, Rt)

Fitness Ranking --> f(f(Ra, Re), f(Rv,  Rt))

   Let f(Ra, Re) = avg(Ra, Re)
   Let f(Rv, Rt) = avg(Rv, Rt)
   Let f(f(Ra, Re), f(Rv,  Rt)) = avg(Ra, Re) * avg(Rv, Rt)

2012: 1.035
2019: 1.185
2016: 1.175*1.19 =  1.398

Hi cognitive
   I just took the simple average of the 4 ratios for each year.  Those ratios are based on values not ranks.

   I can see utility in separating out the 2D and 3D combined ratios.  I don't see advantage of multiplying the 2D * 3D vs. to get the overall combined score vs. just taking the average of the 2D and 3D scores.  They each have two components so every measure gets the same weight by using simple average.  Same is true for multiplying.  I don't think multiplying would change the combined rankings and the final value would be less intuitive, i.e. more difficult to relate to the individual component values.  But if there is an advantage to multiplying 2D * 3D I will consider an explanation for what that advantage is and use if it makes sense to me.

   I thought about differential weighting since Volume seems to me to be the best overall indicator for health of the ice.  But every measure has its pros and cons.

    Extent gets blown up and down by the wind, so in some sense isn't a strong indicator.  But it is the only one that is directly lmeasured.

    Area has more info, but in the full document I repeat cautions from NSIDC about Area getting fooled by melt ponds.

    Volume would be the best if we had a direct measure, but we don't.  We have the PIOMAS model which is an estimate subject to errors as are all model estimates.

    Thickness as I understand it is extrapolated from a relatively small number of direct measures so also has estimate error.

     If I sound like I know what I'm talking about, don't be fooled.  This is just how it all looks to me from reading at NSIDC and PIOMAS sites and ASIF of course.

    By the way, full document did not get the final corrections.  Will try to get the finalized PDF version posted tonight.  The tables shown in the post above have all the corrections I could find. 
     I hope to update all the estimates when the July PIOMAS Volume and Thickness data come out in early August.  I wish there was daily update of PIOMAS Vol and Thick, or even weekly. Great to have Wipneus providing mid month Vol.  Did not see his mid month Thickness value, so most recent I had was from way back in June 30.

    One thing that jumps out to me is the notion that 2012 had help from 2010 and 2011 softening up the ice.  Heading into 2012, 2011 and 2010 were #1 and #2 in the all time combined ranking.  Heading into 2020, it looks like 2018 and 2019 will be #7 and #2 (and 2017 at #5).  Less of a setup than 2012 had. 

    But apart from all the number crunching the big picture is obvious and alarming.  The ship is taking on water, the house is on fire.  Pick your favorite metaphor and talk about what you see in Neven's most excellent ASIF with people you interact with.  Political action requires people talking about it as  the necessary first step. Research shows most people never talk about the climate crisis. Politicians tell me they don't hear much about it from their constituents, and that only the squeaky wheel gets attention and action.  As the AIDS activists realized, silence is death.  It is already too late to prevent bad consequences, but we can prevent worse consequences.  We have to try.
 What else ya gonna do? (end of sermon).

Arctic sea ice / Re: 2019 vs 2012
« on: July 28, 2019, 05:18:28 PM »
Now are those numbers on the scorecard rankings?

Hi Eric
  Left column of each table is ordinal rank.  Ratio is each year's minimum relative to the all time minimum for that measure.  The projected 2019 volume is the all time low volume, so its ratio for volume is 1.00 (i.e it matches itself).  The 2012 min volume was 5% larger than that so it has a ratio of 1.05 for volume.

Arctic sea ice / Re: "Stupid" Questions :o
« on: July 28, 2019, 08:43:44 AM »
Unless people are burning furniture as cooking fuel! 
But this isn't funny really.  We've really got to get the politicians to wake up.
Who ever thought thermometer readings would become a matter of ideological distortion?

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. 

Arctic sea ice / Re: The 2019 melting season
« on: July 28, 2019, 05:06:20 AM »
Since it is time sensitive (i.e. going out of date as we speak), just a heads up for those who like numbers that I posted 2019 vs 2012 Extent, Area, Volume and Thickness values to most recent observation date over in the "2019 vs 2012" thread:,2792.msg216777.html#msg216777

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)

   -- 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.

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


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
(but that server is misbehaving 7/27/2019, should be fixed by Monday).

2012vs2019 NSIDC concentration images

Some people have use for the updated regional data files:

Dear Wipneus
Truly and thanks.  I can get the daily PIOMAS volumes by adding up the regional values from the file you post at

Can you also share the mid-month update for daily Thickness values?  The latest Thickness I can find on the PIOMAS site are from June 30. 

Or if not, what was the PIOMAS thickness on July 15, 2019?

Thanks much.  I have a detailed summary of 2019 vs. previous years I'd like to post that uses the latest available PIOMAS values.  I have NSIDC Extent and Area (thanks to you) up through July 26, and Volume up to July 15, but Thickness stops at June 30.

(Sorry if I am missing something blatantly obvious, wouldn't be the first time.)

Arctic sea ice / Re: 2019 vs 2012
« on: July 15, 2019, 06:46:19 PM »

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 15, 2019, 06:20:00 PM »
the conclusion seems to repeatedly be that it isn't as bad as we feared.

Whichever "we" said that, they would be wrong.  Measurements and projections of both the ASI loss trajectory and impacts have shown increase over time more often than decrease.  (This also applies to climate disruption in general.)

Check out the 16 minute "A World Without Ice" author interview Neven posted the other day at the ASIB.

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 15, 2019, 05:17:58 PM »
Watching the ice flow back toward the AO from the Nares also illustrates this,

AO = Arctic Oscillation atmospheric pattern, not a place.  I don't understand what AO means here.

Tealight's High Arctic analyses also use the same 7 seas. That is really useful- being able to match extent, area and volume, to AWP.

What is AWP?  It is not in the glossary.

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"
    "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. "

Arctic sea ice / Re: Glossary ... for newbies and others
« on: July 14, 2019, 04:02:22 AM »
NP North Pole

Arctic sea ice / Re: The 2019 melting season
« on: July 14, 2019, 03:57:33 AM »
     The "percent of melt season completed by this date" values shown by gerontocrat in the Data thread are almost certainly still applicable in 2019.  Those values include prior years when there was a lot of ice above 80N, so that's not really a new factor this year.  And the daily Extent and Area average loss curves he shows also indicate that we are just past the peak of daily melt values, and that there is a solid month of high melt potential before things start slowing down after August 16. 

    Above my skill set, but my hunch is that there opportunity for more surprises in 2019 -- perhaps another Arctic dipole, a "stuck" system with high air, reinvigorated Fram transport, GAC II, or something I can't even think of.  All bets are off with a less tethered polar jet no longer keeping things organized.

     I learn from and enjoy the speculation about the current situation and what is left to occur between now and September, and beyond.  For predictive ability it seems that the simple extrapolations of cumulative remaining melt from this date to the minimum in previous years shown by gerontocrat are as good a predictor as we have, especially now that we are about 2/3 of the way through the melt season. 
     ...But now I'll contradict what I just said...  The thing that spooks me about 2019 is the terrible condition of the ice and the cumulative loss of MYI.  At some point, that has to have a compelling impact on September minimum.  Maybe not this year, but my guess is that there are not many years left before the cumulative damage reaches a tipping point whereby functional changes allow a big Arctic-wide cliff from a single driving cause, or a synergism of events.

     One other factor this year is a lot more Alaskan wild fires than usual.  With the persistent torching heat in Siberia in May and June, I would guess that fire activity is increased on that side in 2019 too.  Not surprisingly (though not necessary due to the fires) the Arctic albedo in 2019 is very low this year (=higher albedo warming potential), one more factor that affect the next month of high melt potential.

PS -- Does anybody know why the NSIDC ASI concentration image says "No Data"? I hope the beyond-its-rated-lifetime satellite isn't blinking out.  They still have the daily extent data up to date, so I don't think that is the problem. 

Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: July 13, 2019, 03:54:47 PM »
Thanks Ardeus.  Yes that is the one.  The jet stream part starts aroud 12:00.
(And thanks for doing the interview.)

 "Just Have A Think" also did a 4-part interview with Wadhams.  In part 1 he briefly discusses jet stream impact (starting at about 8:30). 

Arctic sea ice / Re: 2019 vs 2012
« on: July 11, 2019, 08:51:18 PM »
absotively true, but everytime I bring this up, I see eyes rolling up. People just don't want to hear about catastrophe unless it's on their doorstep...

Agreed, but it still needs to be said.  And I bet your bringing it up makes a difference to those people (like kids who don't seem like they listen  then 10 years later they remind of something you said that shows they really were hearing you all along).

The AIDS campaigners pegged it - Silence is death.  Politicians have told me they'd do more on climate crisis but they just don't hear about it from constituents.  I think the tide is changing on that in U.S.   With 2020 election ramping up, climate is getting some respect for the first time.  Still only 14 minutes in first 4 hours of Dem candidate debates.  But that 14 minutes is more than TOTAL discussion of climate during all of the 2016 debates. 

Social change studies show that things don't change, and don't change, and don't change, until... seemingly in a flash, for no obvious reason, they do change very quickly.  But that slow incremental process from 1 to 2 to 3% etc. was what made it possible.  Gay marriage in the U.S. is a striking example.

Studies also show that only 10% of population needs to adopt an idea before it catches like wildfire.   While much more than 10% are already aware and concerned about climate, we need to get over the 10% hump of population ready to take on the large scale systemic change needed -- that WWII type mobilization often cited as the model for what needs to happen.  So yes, 95% may act like they aren't listening, but having it in conversation over and over is the way we get to that 10% threshold IMHO.  We gotta try. 

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 ...

    ... 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.

Arctic sea ice / Re: The 2019 melting season
« on: July 11, 2019, 07:41:03 PM »
But it seems that after Slater's death in 2016, someone else has taken over, and the Slater map has been oversimplified.  The map is now lumping together grid points with the same concentration and does NOT take into account the location of the grid points (e.g. whether they are in Hudson Bay or rather in the Central Arctic).

This was discussed last year too:,2278.msg158317.html#msg158317

Wow, if that is the case, they should pull the plug on the Slater model, or at least take his name off of it.  Failing to differentiate between Hudson Bay and CAB grid points seems like malpractice and an insult to Slater's legacy. 

Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 11, 2019, 07:35:06 PM »
A cautionary tale
So I had a look to see if ESS area was lowest in the satellite record. It is not.
So I had a look to see in which year on this day was area lowest.
The answer?1990, 29 years ago.[/i]

Thanks for all the great number crunching gerontocrat, Juan C. Garcia, Alphabet Hotel, Killian, uniquorn, Aluminum and others. 

gerontocrat --  any insight on what caused the ESS crash in 1990?  That was a tremendous anomaly esp. for its time (oh no, I'm starting to talk like Trump).  Was there a storm, a heat wave, or did the USSR get rid of leftover nukes over the ESS?

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,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

     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. 

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

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,2533.msg211770.html#msg211770.  And the even more dramatic 365-day running average volume posted at,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.       

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.

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.

Arctic sea ice / Re: The 2019 melting season
« on: June 28, 2019, 08:59:17 PM »
RE Pagphilus post #2776 on Albedo

   - At Reply #55  in "Atmospheric connections, structure, and long range weather forecasting" you can see abstracts of two recent studies on the effect of current (as 2011) and future (ice free summer Arctic Ocean in ?) albedo change from Arctic sea ice decline on global energy balance. 

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

"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

"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%.

Arctic sea ice / Re: The 2019 melting season
« on: June 26, 2019, 12:39:02 AM »
+1 Steerpike.

   No need for arguments about the 2019 minimum, having a different opinion doesn't make you a denier.  We will all have our hunches confirmed or refuted soon enough. 

    The next 6 weeks will be interesting no matter what happens.
For those of you keeping score at home.

Arctic sea ice / Re: "Stupid" Questions :o
« on: June 25, 2019, 11:41:54 PM »
     Has anyone come up with a numerical relationship between Arctic sea ice compactness and average pack rotation speed, or amount of export out the Fram Strait? 

     I'm spooked by the idea that decades of  cumulative thinning and removal of old ice as anchors has led to a functionally new state in the CAB ice pack making it more vulnerable to wind or current driven transport. 

   During the GAC in 2012 there were comments that if the ice had been thicker the cyclone damage to the ice would have been much less, but the average thickness by then had been reduced enough to allow much more wave damage.  Since 2012 the trend towards thinner and more rotten ice has had another 7 years to make the remaining ice even more vulnerable today.  Any observations about average pack rotation 2019 vs. earlier years much appreciated. 

   Wipneus's Farm Strait export chart doesn't show increasing export trend, so my logic may be missing key factor.  And I don't know of any other measure of export loss or pack mobility.  It just seems to be rotating more this year.  If there was a correlation of mobility or transport with compactness that would at least provide a measure to track this issue and indicate I'm not making all this up in my head. 

Arctic sea ice / Re: The 2019 melting season
« on: June 24, 2019, 06:30:58 PM »
I don't have the experience to be convinced of my hunches.  Looking at cavitycreep's animation post #2393, makes me wonder what others think about two observations:

1.  It seems that multi-year trend towards thinning and rotten ice has reached a tipping point.  The effect being that when combined with the destructive current and near term weather forecast, the indicator measures (Extent, Area, Volume) are primed to go off a cliff in the next week, are likely to reach 2012 level even without an August cyclone, and below it if there is one.  Of course it all depends on July weather, but from what the weather gurus on this forum are saying there is no apparent weather relief for the ice in sight.  The persistence of the northern Siberia roasting for week after week is searing my memory as well as the permafrost.   

Except for nooks and crannies left in the CAA, it looks like by October 2019 the extinction of 4- and 5- year old ice could be largely complete. 

2.  Is the CAB pack rotation more mobile this year?  Wind speeds do not seem abnormal which makes me wonder if enhanced mobility of weaker, fractured ice  is another reinforcing feedback driving the 2019 melt season.  Or (if mobility is indeed higher) is the positioning of the High and Low cells and resultant wind orientation the only factor that really matters?   

Fish - Is there precedent for Atlantic ocean heat intrusion meeting up with Pacific side?  Any chance of that happening this year?

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