By Steve Goddard
In my previous PIOMAS verification piece I noted that PIOMAS volume trends don’t correlate with extent trends over the last three years. PIOMAS has gone down since 2007, while extents have increased.
The diverging trends themselves prove nothing, because it possible (but unlikely) for it to occur. This time I directly compared calculated volume measurements, which should be more definitive.
In their current graph (below) PIOMAS shows a record negative volume anomaly.
This appears to be incorrect, because we can see from the PIPS blink maps (below) that thicknesses were generally lower on this date in 2008. If the visual impression is correct, it would be impossible for the current anomaly to be greater in magnitude than the 2008 anomaly.
Quantifying this further, I numerically integrated May 31 pixel count vs. thickness since 2000.
As you can see, May 31, 2010 volume is currently higher than any year since 2006. It is also higher than 2003. Remember that 2003 had the highest minimum of any year in the JAXA record.
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent.png
So why does PIOMAS show a record volume anomaly at present? Something is wrong either with PIPS maps or published PIOMAS volume data. PIOMAS trends are widely quoted and it is important for them to be correct.
Willis has also made some interesting observations.
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geo says:
June 2, 2010 at 6:40 am
Yeah, a change in algorithm, even a small one, starting May 20th might have given 2010 the edge against 2006.
05,31,2010 11,086,250 km²
05,31,2006 11,102,344 km²
It’s a difference of only 16,094²
But the interesting facet of the 2010 drop was not the final point in May – it was the fact that it cut across the curves from 2009, 2008, 2003, 2005, 2007, 2004 and 2006 (the 2002 curve did not start till mid-June 2002).
Cutting across all the other curves means it was the fastest rate of decline in the fast-melt 21st century data of IARC-JAXA. Of course, if it now tracks 2006, I will lose my next bet, that 2010 will have a lower minimum than 2009.
Anu says:
June 2, 2010 at 8:21 am
Cutting across all the other curves means it was the fastest rate of decline in the fast-melt 21st century data of IARC-JAXA. Of course, if it now tracks 2006, I will lose my next bet, that 2010 will have a lower minimum than 2009.
++++
I think you have to put that decline in the context of what happened in late March, which was an unusual “late spurt” in extent growth. IMO, what we’ve seen since is how ephemeral that kind of late season spurt is. Coming that late, it could not have had much thickness at all –forget “multi-year ice”, this was barely “multi-week” ice!
It will be very interesting to see if 2010 can hold the 2006 line for the rest of the melt season, particularly when we get into August. 2010 has more multi-year ice than 2008 or 2009, but unlikely it has as much as 2006 did at this point in the melt season.
Anu
I did a post a few weeks ago correlating monthly extent with minimum extent. Prior to August, the correlation is essentially zero. Speculating on the summer minimum based on current extent has no scientific merit.
Anu,
The fastest rate of decline based on what comparison? Every May in the record? What about July, when every year has a faster rate of decline than this year did?
If you are going to use the term “fastest” you need to qualify “fastest compared to WHAT”.
Also, if it crossed the 2006 line, why would it now start “tracking” 2006. Why would it not start tracking some other year? Why would it not continue on at a faster rate now that it has crossed all other lines? Or is it possible that May was an anomolous month and has no real significance? I do not know which it is personally, but your “bet” that the line starts “tracking” 2006 has no real basis, at least as far as I can tell from your post.
Anyway, here is MY prediction. The arctic will NOT be “ice free in summer” now, in 2013, or during ANY summer between now and 2040. In fact, Arctic sea ice will not fall below 3.2 X 10^6 sq. km. at any time in the next 30 years. How’s THAT for a long-term prediction?
I should have been more clear in that post… the rate of decline every July is greater than the rate of decline every May, including this May. That isn’t quite how it came out the first time 🙂
blackswhitewash.com said on June 2, 2010 at 3:05 am:
Hits. Page views. This stuff sure seems popular. Look at the comment counts!
Plus it provides some wonderful examples of how web-reviewed science can work. In just the past few weeks of examining temperature and Arctic records, etc, the equivalent investigative work of several years worth of dueling peer-reviewed papers has been performed. We’re doing it for the science, man! Can you dig it?
Models per se are not bad, the issue is accepting and understanding the simplifications and limitations of these miniature versions of reality, like with the not-quite-anatomically-correct Ken doll.
Plus when dealing with data and concepts from one side of an argument, showing that two or more sets have a lack of consistency and coherence between them shows weakness on the whole side. For example Willis is showing how Shepherd et al 2010 does not match up with PIOMAS, so if you support Shepherd you’re tearing down PIOMAS, and the Arctic Ice Death Spiral proponents love PIOMAS. It’s been somewhat entertaining to watch people claim Willis has it all completely totally wrong while, with the somewhat-questionable data provided by Shepherd and PIOMAS, he’s been showing that PIOMAS is likely correct, or at least more correct. Willis’ numbers are (somewhat) agreeing with PIOMAS’ numbers thus (somewhat) verifying PIOMAS, his opponents say Willis’ numbers are (totally) wrong, therefore they are effectively saying… 🙂
Things that-of-course-are-not-amusing you just suddenly realize:
The acronym of “Arctic Ice Death Spiral” is AIDS. This could explain the lack of mentions about AIDS supporters and proponents on the ice threads.
The arctic sea ice volume hindcast was compared with IPCC projections in a JGR paper published in 2007.
http://www.agu.org/pubs/crossref/2007/2006JC003616.shtml
The authors report :
” In lieu of actually observed sea ice thickness, this model result under realistic atmospheric forcing serves as a benchmark for the coupled climate models. The hindcast exhibits virtually no trend in Arctic ice volume over its integration period 1948–2000. Most of the coupled climate models show a negative trend over the 20th century that accelerates towards the end of that century. “
OT understood if not posted but this veteran has had enough of Tamino.
In the middle of his whine fest about being asked a question about flying a flag you find this gem of a post by a Craig Allen:
“As an Australian, to me one of the scariest thing about the US (along with the propensity for ritious vengence) is the extreme patriotism. It seems to be taken for granted by most of you. But to outsiders (and I’ve discussed this with many people of many nationalities) frankly it seems pathological. It’s one of the key characteristics that allows/causes peoples to commit atrocities against other peoples, and to otherwise subjugate them. And Americans who don’t exhibit extreme patriotism increasingly seem fearful of admitting it. It’s scary to watch.”
So I as a patriotic American and veteran I am a pathological person who tends to commit atrocities and I want to subjugate others.
On the other hand if I ask them if they fly a flag on Memorial Day well that is just over the line! Please take a moment to think about who is over the line crazy!
Excerpt from: Jon P on June 2, 2010 at 10:06 am
Out of respect for the site I won’t “go political” and contribute to getting a political thread derailing these ice comments. I will drop off this link showing an egregious example of such distasteful views that readers may choose to examine.
Tom P:
June 2, 2010 at 8:08 am
sure Tom, i’ll humor you in your rationale there under the bridge. You’re doing good. the trolls must look to you.
Tom P:
June 2, 2010 at 8:08 am
Funny how you play with numbers Tom. Lots of “tricks” up those global warming sleeves.
Tom P
My comment was that Arctic ice has increased in volume since 2007.
http://wattsupwiththat.com/2010/06/01/piomas-non-verification-ii/#comment-401984
In reply you post a graph showing volume has decreased since 1980. You tried to prove me wrong by changing the time frame. Maybe you thought no one would notice. That’s how the global warming game goes.
Which shell is the pea under, hey Tom. I had the pea out in the open. You brought in the shells. You changed it into a “trick”. You learned that from Michael Mann?
There is the famous global warming prediction that Arctic ice is in a death spiral. Al Gore said in December 2008 that Arctic ice could be gone in “5 years”. But that ice is heading in the opposite direction. You can throw curves at people trying to distract them from looking at that. But it’s all so lame of you.
Tom P,
You did know this post is about what’s been happening in Arctic ice since 2007 and how the PIOMAS graph is flawed? Maybe my expectations that you understood that were incorrect.
stevengoddard,
While we await Cryosat data or PIPS 3.0 maps, you can rubbish the PIOMAS volume numbers all you like but at least they try to validate their numbers by presenting a comparison to ICESAT volume data. Where’s your validation of your volume calculations based on PIPS 2.0 data against ICESAT? Or anything else? Merely saying the PIPS data must be good because it comes from the navy sounds a great deal like an appeal to authority