A Few Things Ill Considered

Arctic sea ice headed for a new record?

Posted by coby on June 23, 2010
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No too long ago the usual suspects were all a-twitter about arctic sea ice, which was tracking very close to the long term average.

i-ca8b6d42f30d51a74c516f3df9976347-nsidc_n_stddev_timeseries_033110-thumb-500x400-51631.png

This was in late March, and though you would think a weather man would understand what weather is, this temporary upwards tic prompted the remarkable vapidity of this lead: “We’ve all seen that Arctic Sea ice area and extent has expanded and is back to normal”.

Well, that was then, and this is now:

i-7b1bc6ef55513ba3c5b4f9f9e0e805bb-nsidc_n_stddev_timeseries_062310-thumb-500x400-51635.png

Now, not only have we left the long term average behind, the current seasonal extent has dipped below one standard deviation less than normal and is even well below the record low of 2007. (It is worth noting that an actual return to normal levels would mean an equal amount of time spent above the normal line as spent below, not a brief one month visit)

This is noisy data, you have to sift through it mathematically to find the real signal. One single “normal” reading does not mean arctic ice decline has ceased.

If Anthony Watts does not know that, he is not qualified to draw any conclusions about climate change and is barely qualified to read the teleprompter for a local weather report. If he does not know that and does not publish the conclusion that today Arctic sea ice is disappearing faster than ever he is a hypocrite. If he does know that, he is a liar. I have my own opinion.

If we want to know what is happening to long term trends in arctic sea ice we have to look at the last several decades.

i-3cbdbfcb9fdf9f9650be238ed1bcde99-20091005_Figure3-thumb-500x369-51639.png
(source)

The trend is unequivocally down and a new record this year will lend weight to the view that it is accelerating. The so called “recovery” of the last two years does not even get us above this trajectory, and certainly does not reverse it. If this year is a new record, I would hope that particular turd can be laid to rest.

It is further worth noting that this discussion is all about ice extent, ice volume is arguabley a much better quantity to monitor. That trend looks like this:

i-0d9bf9f3f35bc0a2c875d9e6c35f3d87-20100608_volume_trend-thumb-500x359-51642.png
(source)

Note that the recovery in extent from the 2007 low is not matched by a recovery in volume. This is because once old, thick ice melts it can only be replaced by young, thin ice. 5 year sea ice can not recover in one, two or even four years.

Arctic sea ice is shrinking rapidly. Denying this is about as reasonable as denying that CO2 is increasing.

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Comments

  1. #1 James Hrynyshyn
    June 23, 2010

    Probably would be wise to anticipate the objection that the sea ice volume graph was generated by a computer model, and does not represent actual measurements. It’s still valid, but always best to not appear that you’re hiding an incline….

  2. #2 GFW
    June 23, 2010

    Maybe it’s just confusing wording, or maybe you’re underselling the truth, but “dipped below one standard deviation less than normal” doesn’t describe the current situation. We’re more than 3, almost 4 standard deviations below the “normal” line right now. The grey area on the NSIDC chart is 2 std dev.

  3. #3 Scott A Mandia
    June 23, 2010

    Well done, Coby. WUWT has no clue or is intentionally misleading (probably both).

    James, the PIOMAS is the nicest visual but there are plenty of “real” images that Watts et al. cannot object to.

    See: Modern Day Climate Change – Ice

  4. #4 crakar24
    June 23, 2010

    I thought you were away in Europe somewhere Coby?

    A quick (serious, non denialist) question, is the ice melting because of an increase in air temp or water temp or a combination of both?

    Cheers

  5. #5 marktime
    June 24, 2010

    Here’s a link to a temporary sea-ice blog that I think Coby’s readers will enjoy. (Nothing to do with me, I just think it’s great :-) ).

    http://neven1.typepad.com/blog/

  6. #6 t_p_hamilton
    June 24, 2010

    crakar asks:”A quick (serious, non denialist) question, is the ice melting because of an increase in air temp or water temp or a combination of both?”

    It is increased heat, not temperature. Take a glass of ice at 0 degrees C. Melt the ice to water by adding heat. It is still zero degrees C. THEN adding heat will raise the temperature.

    As arctic ice shrinks during the summer, arctic temperatures where all ice/snow is melted will increase. The primary effect of thwe greenhouse effect is not so only the ice melting, but delay in refreezing (which of course means less ice to melt next year).

  7. #7 Tony Sidaway
    June 24, 2010

    Thanks for a very clear exposition. Some blog posts had noted the dip below the 2007 line a few weeks ago but I didn’t attach much significance to it because that was just a snapshot. This now looks quite unusual. I’ll be watching in September to see what becomes of it.

  8. #8 Steve L
    June 25, 2010

    In as much as thickness affects rate of melt and therefore extent when days are longest, I would agree that thickness is as important as extent or maybe more. But in terms of feedbacks, I think extent or area are more important than thickness. The case for such thinking is even stronger considering that first year ice tends to be brighter (more reflective) than multi-year ice (bluer).
    Correct?
    If so, then the fact that extent was below the record for the weeks nearest the summer solstice is of much more consequence than either the September minimum (which is what folks tend to point to) or the feb/march maximum (which Watts pointed to and is probably one of the least important).
    It doesn’t matter what I think, but I’m curious to see if others agree.

  9. #9 coby
    June 25, 2010

    That same point occured to me as I was writing, extent is what determines the albedo impact. When deciding what is more important, I guess it just depends on what you are interested in, climatic impact or rate of ice loss.

  10. #10 Tony Sidaway
    June 25, 2010

    The higher albedo of new ice could be expected to hamper the effect of direct radiation during the summer melt, and we can expect to learn a lot about that in the near future.

    But that way of looking at things seems to understate the magnitude of the changes to a climate that once was fairly self-contained, locked in by deep layers of consolidated sea ice. The future climate of the arctic seems quite likely to interact much more with ocean currents which, with the diminishing extent and influence of the old heavy, multi-year pack, will exercise a much stronger influence on the life cycle of arctic ice.

  11. #11 crakar24
    June 27, 2010

    TP @6,

    Not sure i follow exactly, is the increased heat found in the water or in the air?

  12. #12 adelady
    June 27, 2010

    Where’s the heat?

    Short term it’s the same as every other year. Direct sunlight on the water and the surface of the ice.

    Long term? As a non-scientific lurker around here, I like to use analogies whenever I can to make things clearer. (This strategy fails completely of course when I’m faced with maths or physics of any complexity.) Long term it’s warming both in water and atmosphere that drives the whole system to be weaker when challenged by routine physical stress – summer.

    In a human body, osteoporosis has the same effect. The skeleton gets progressively weaker but people can walk and climb stairs until, one day, getting out of a chair breaks a hip. A routine physical demand on the body is suddenly catastrophic.

    A poor analogy but vivid nevertheless.

  13. #13 t_p_hamilton
    June 28, 2010

    Crakar,

    Almost all of the heat absorption goes into 1) melting ice (heat of fusion) and 2) warming the water

    Heat emission occurs mostly at night (winter) and is slowed by the greenhouse effect.

  14. #14 Jack Savage
    July 26, 2010

    Arctic sea ice extent seems to have staged a recovery, now we are at the 26th July, or should I now be looking at a different graph? Oh right… I should only look at Piomas,now?
    In any event,regarding extent, surely the yearly high and low points are what actually matter?

    “If he does not know that and does not publish the conclusion that today Arctic sea ice is disappearing faster than ever he is a hypocrite. If he does know that, he is a liar. I have my own opinion.”

    Bold words. Should there not be a third choice? That a further recovery from the 2007 low might suggest it was not disappearing faster than ever? When we only have decent data for a few decades? How far into the past does “ever” reach?
    I shall watch with interest.

  15. #15 coby
    July 26, 2010

    Jack, it is ludicrous to call a return to the downward trend line a “recovery”. No single data point can lead to the conclusion that the steep downward trend has reversed.

    Yes, I agree the more significant data points are the maximums and minimums. The hypocrisy of sites like WUWT is that they trumpet single data points when it suits their false narrative (arctic ice is recovering) and remain silent when it does not.

    If you are inclined to level that charge at me, I only request that you quote me drawing any conclusion from any short term fluctuation.

  16. #16 mandas
    July 26, 2010

    Jack

    Ummmm – what is the source of your claim that “Arctic sea ice extent seems to have staged a recovery”?? It would make interesting reading, because it is the complete opposite to every other piece of data on the subject. (or maybe you use a different definition of the word ‘recovery’ to the rest of the world).

    Please explain.

  17. #17 Jack Savage
    July 27, 2010

    A recovery from the low point illustrated in the Artic Sea Ice Extent graph in this post.
    The same graph now shows the extent to lie between the so-called lowest ever 2007 record and the average.
    This would mean that the ice is (at present) NOT “disappearing faster than ever”.Can this not legitimately be called a recovery?
    As I have said before, I give this no particular significance ( as I would have thought the final position when the melt stops is the main point of interest) except as an illustration that the incontinent language was not only rude, but presently inaccurate. When and if the final resting point for the 2010 melt is below that of the 2007 one, then and only then is surely the time for “I told you so”?

  18. #18 Dappledwater
    July 27, 2010

    Mandas, by Jack Savage’s definition, a terminal cancer patient can have multiple “recoveries” before they die.

  19. #19 Jack Savage
    July 27, 2010

    Dappled water:

    Hilarious,but I think you will find that Coby uses the term recovery to describe just the same effect in this very article. Did you bother to actually read the article?
    Don’t you lot ever get bored with the cheap shot?
    If all you want to read in these comments is sycophantic agreement, why do you not go over to RealClimate, where the moderators will oblige.
    Any chance of you addressing the argument?

  20. #20 Chris S.
    July 27, 2010

    Jack:

    If you want sycophancy surely Climate Audit or WUWT are the place?

    Regarding your claim: “I think you will find that Coby uses the term recovery to describe just the same effect in this very article”.

    Is this a prime example of selective reading that seems a common trait among the WUWT crowd?

    Do you mean here?: “The trend is unequivocally down and a new record this year will lend weight to the view that it is accelerating. The so called “recovery” of the last two years does not even get us above this trajectory, and certainly does not reverse it. If this year is a new record, I would hope that particular turd can be laid to rest.” (Note the quotation marks around the word recovery and the appellation “this particular turd”).

    Take a close look at Figure 3 above and show me where there is even a hint of recovery.

  21. #21 mandas
    July 27, 2010

    Chris

    The definition of a recovery that Jack is suggesting seems to be that, while things are still getting worse, they are not getting bad as fast as they were before. And that has to be the funniest definition I have ever read in my life. And to be fair, I don’t think that even Jack believes it. I mean, no-one in their right mind would define ‘recovery’ as ‘a slower rate of decline’.

    We all know the ice in the Arctic is not declining as fast as it was in May/June. You only have to read the NSIDC data and comments to realise that. But we all know that is meaningless in the context of climate change. The long term trend clearly shows a decline. The extent is more than two standard deviations below the long term average. And while the extent is not the worst it has ever been in the instrumental record (2007), it is the second worst it has ever been (worse than 2006).

    So don’t be too hard on Jack. He knows he is wrong, but he is just being human and doesn’t want to admit it and lose face.

  22. #22 Robert Grumbine
    July 27, 2010

    Coby (9) —
    You’re a bit wrong there. Extent as such isn’t what is important to albedo effects. Neither is area as such. Rather, it is the albedo change (between ice and ocean) times area times solar input, summed over all areas of the Arctic.

    The thing is, it really is an area of ice that is reflecting sunlight, rather than an extent. But it also matters where that reflecting ice is. If we’re talking the high Arctic in winter, there’s no sun, so no albedo effect. This time of year, there is a lot of sun (more in some places than others), so you then have to examine whether the changed area/extent is occurring in places that have more sun or less.

    Then there are clouds. Replacing ocean for ice, or vice versa, is one thing. But if they’re both under highly reflective clouds, there’s not much albedo effect regardless of what you do at the surface. … except it isn’t always cloudy, and … all sorts of chickens and eggs and feedbacks.

    Anyhow a quickie on what matters for albedo. Remind me to make it a full length post at my place.

  23. #23 Chris S.
    July 27, 2010

    Dr. Grumbine. A quick question: Does the age of the ice have any affect on the albedo? Intuitively I would expect older ice to be ‘dirtier’ and thus less reflective.

  24. #24 Jack Savage
    July 28, 2010

    At Chris S.

    “Note that the recovery in extent from the 2007 low is not matched by a recovery in volume. This is because once old, thick ice melts it can only be replaced by young, thin ice. 5 year sea ice can not recover in one, two or even four years.”

    Note the absence of quotation marks around the word “recovery” and tell me again about the phenomenon of “selected reading”.

    Mandas

    “So don’t be too hard on Jack. He knows he is wrong, but he is just being human and doesn’t want to admit it and lose face.”

    What is one to do in the face of intellectual argument like this? I use the word “recovery”…everyone knows what I mean but seem to think it is in some way an argument to misinterpret it. Say it how you will, the position now is that extent is tracking above the 2007 low. I chose to use the same word as Coby did. I am deeply sorry, and I apologise on both my and his behalf .If you do not like the word “recovery” then use “hypocrite” or “liar”.

    “I mean, no-one in their right mind would define ‘recovery’ as ‘a slower rate of decline’.”

    Coby! Take your meds!

    I am wasting no more time here, either mine or yours, for the present. ( Except maybe to sneak a peek later to see what other gems of humour at my expense have crystallised) I do not mind having my leg pulled and I have a thick skin. I have learned a lot from this site, but very little from the likes of mandas.
    One more point….on the subject of hypocrisy…you guys have all given up flying in airplanes, hav’nt you?
    Byee!

  25. #25 Dappledwater
    July 28, 2010

    Jack Savage “One more point….on the subject of hypocrisy…you guys have all given up flying in airplanes, hav’nt you?”

    Yes, and much more too. Will it make a difference if the rest of the world doesn’t pull their heads out of their backsides?. Nope.

  26. #26 Chris S.
    July 28, 2010

    Jack, which came first – your quote or mine?

    Had another look at figure 3 yet?

  27. #27 coby
    July 28, 2010

    I don’t think we can blame Jack for using the term “recovery” as he did, he’s right I did it first. It is a poor word choice but mostly because of the disengenous ways it is spun by WUWT et al. I think among reasonable people context should be enough so that we know when using that word to describe a higher minimum this year than the year before it does not imply anything about long term trends.

    I don’t think Jack is that mislead either.

    I do think that 30 years of direct measurements is enough to recognize what is normal annual variation, what the decadal trends are and a bit about how those trends are changing.

    I am pretty sure there is a longer record of arctic sea ice out there somewhere, anyone have a link?

  28. #28 Robert Grumbine
    July 28, 2010

    Chris S.
    (aside: I only use the ‘Dr.’ title in very unusual circumstances. Going straight to ‘Robert’ is fine on the web.)

    Your intuition is entirely correct for snow. It’s actually a large enough effect that numerical weather prediction models make some efforts to include it.

    For the sea ice, I’m not sure how it works out in practice. Dirty ice will tend to melt sooner, leaving behind cleaner (higher albedo?) ice. On the other hand, after melting out the saltier and dirtier parts, the ice should be clearer (my intuition speaking), which means that less energy would be reflected (lower albedo). It’d pass through the ice and in to the water column. Let me encourage you to pursue the question on google scholar (scholar.google.com) and see what the observations have to say. I know that they do exist.

    coby (28):
    I took up your question of longer records of arctic ice in http://moregrumbinescience.blogspot.com/2009/01/ice-before-1979.html
    (Some snark involved in the post. I’d recently encountered a batch of silliness claiming that we knew nothing about ice before 1979.)
    In short: yes, there are longer records. Depending on what you want, back to 1750.