2011-09-08 15:21:50Arctic Sea Ice
Robert Way

robert_way19@hotmail...
142.162.11.164

Lost in all the confusion with the Spencer and Dessler papers is that the Arctic Sea Ice is about to hit the minimum extent on record according to NSIDC.



2011-09-08 19:51:17
Tom Curtis

t.r.curtis@gmail...
112.213.162.57

Still 200,000 Km^2 shy of the mark by my reckoning.  Obviously the arctic sea ice extent is continuting its strong recovery from the 2007 low ;)

2011-09-08 22:51:48Obsession with extent obscures the real problem
John Cook

john@skepticalscience...
123.211.208.191

The *total amount* of Arctic sea ice hit record low levels in 2010 and again in 2011. So regardless of what extent does, Arctic sea ice is ALREADY at record low levels. That should always be stressed in any blog posts about Arctic sea ice.

2011-09-08 22:57:18Comment
Robert Way

robert_way19@hotmail...
142.162.19.186

John,
Yes there is an obsession with extent and area but there are good justifications for that. At the end of the day it is the extent that is important for the energy balance more so than volume. That being said the volume is linked to the extent obviously in that less volume will lead to lesser extents. On the flip side the other issue is that a lot of people don't like relying on a model like that of Piomas to calculate the volume. I don't have any criticisms of them but at the end of the day the results that piomas are giving is likely a good representation but is not the actual measured values across the entire arctic. Cryosat 2 will alleviate some of the issues undoubtedly.

2011-09-08 23:23:55The "Death Spiral" continues...unabated
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Actual on-the-ice measurements of thicknesses (from the Polarstern):

"Initial measurements of the ice thickness confirm this: in 2011 as well as in 2007 the most frequently occurring ice thickness was 0.9 metres. As a comparison, the most frequently measured ice thickness in 2001 was around 2 metres. In that year the extent of the ice cover at the end of the melting period corresponded roughly to the long-term mean."

Thickness lost is correlating well to volume losses, as calculated by Piomas.  And following right on the trend line from Maslowski:

Arctic Ice Volume

[Source]

2011-09-08 23:29:52The times they are a changin'
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Area just hit rock-bottom (all-time low):

Arctic Sea Ice Area

[Source]

 

Apropos:

http://www.youtube.com/watch?v=p8UNvO4QDx8&feature=player_detailpage

2011-09-08 23:38:58Cryosphere Today Animation
Sphaerica

Bob@Lacatena...
76.28.5.93

I personally get the most out of watching (regularly) the 30 day animation at Cryosphere Today, as it's far more multidimensional (in space, time and concentration, lacking only the vertical depth of the ice) than any of the extent, area or volume linear graphs.  It can also be compared, through their Archive, to images from previous years at the same date, or to find the date in a previous year which had a near equivalent image and so look forward from there.

By doing that this entire melt season, it's been pretty obvious where we've been headed, and where there are some major differences (such as the ice melting/pulling well away from Zemlya, which only seems to have happened before in 2005).  Things have slowed some lately... the increase in density as well as the North Pole Cam both show that things are refreezing substantially within the 80N circle.  Now it appears to be a "game" of how much melting will continue at the edges, and how currents will push ice out of the cooler regions and into warmer areas (which increases the extent on all of the graphs, but actually causes more ice to melt).  The other thing I can't see is how warm the water still might be, continuing to melt things from underneath even as they freeze above.

We're in uncharted territory, though, so trying to imagine how things will go in the next two weeks is tough.

2011-09-09 02:21:47
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

I agree with John, it is all about volume now becasue the ice is so thin and rotten, metrics like sea ice exctent do not mean much anymore.

Another aspect of this is look how much the oceans are warming in those ice free areas...yikes!

Update: reduced image size 

2011-09-09 02:46:57
Riccardo

riccardoreitano@tiscali...
93.147.82.143

In the end it doesn't matter. Extent, area, volume or whatever are and will keep going down more or less together.

P.S. please limit image width

2011-09-09 02:47:23
Sphaerica

Bob@Lacatena...
76.28.5.93

Albatross... interesting and scary.  I wonder if that means that this year's peripheral melt season will last days or even a week longer than it has in even the recent past.  At a minimum, this implies thatanything that is blue below may be gone by the time we hit this year's minimum.

CT Image 09 07 2011

2011-09-09 03:03:40
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Sphaerica, I fear that you may be right.  To be honest though, this is so outside the old conceptual models  that I dare not even hazard a guess how this will pan out.

2011-09-09 03:22:51Fodder for series?
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

There's enough material already posted on this comment thread for an article or two. Perhaps a new series (Arctic Sea Ice in Decline: 2011) should be generated?     

2011-09-09 03:32:43
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Badger, indeed.  But let us wait until the final numbers are in-- I wonder when that will be if the melt season is prolonged?

2011-09-09 04:14:25comment
Robert Way

robert_way19@hotmail...
134.153.162.53

I do agree with all of you that volume is of course a more important diagnosis tool but I still think the extent reaching a minimum is a very important event...

We certainly have plenty for a few articles but I suggest we wait a bit on that.

Back when the Piomas data first came out I was looking at doing a post, never got around to it though it is summarized here:

http://www.skepticalscience.com/pics/SeaIceVolume.pdf

2011-09-09 05:40:15
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Neven will have a new post out tonight dealing with ice thicknesses found by the Polarstern.