Cryosphere Today 2015 Arctic SIA daily minimum: June poll

[Neven]

ATTENTION: There are two polls on the ASIF. One is for NSIDC sea ice extent monthly/September average minimum, the other is for Cryosphere Today sea ice area daily minimum. Make sure you are aware of the difference before voting. You can discuss various extent/area data sets in this dedicated thread.

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This CT SIA poll will run for 10 days (until June 14th). Until then you can change your vote. There will be a new poll next month.

Here's how things are currently looking based on data up to June 3rd:



These are the daily minimums for the last 7 years (in millions km2):

    2005: 4.092
    2006: 4.030
    2007: 2.919
    2008: 3.004
    2009: 3.425
    2010: 3.072
    2011: 2.905
    2012: 2.234
    2013: 3.554
    2014: 3.483

You can use the comment thread below to motivate your choice, but discuss various SIE/SIA data sets in this dedicated thread.

[Neven]

Oh, and there's a meta-vote going on too: I'll only open a next vote in July if at least 100 people vote. EROEI and all that. 

[Neven]

Based on my interpretation so far, as just posted on the ASIB, I'm going to go for something just below the last two rebound melting seasons: Between 3.0 and 3.25 million km2. I'd go one bin higher, but that's no fun. 

[Peter Ellis]

Wild-ass guess, somewhere around 2007 /2010 / 2011

[Nightvid Cole]

I say 1.75-2.0, because I said extent-wise we should come out like 2012; however area-wise I think we will be lower because there will be a lot of "slush" of very low concentration around the North Pole, like we saw in 2010 and 2013. This is also based on snow retreat.

[icefisher]

I am guessing that area will be between 3.08-3.19.  It could go higher if we get cyclone spreading of fringe ice areas during September.  Volume 5000-5500?

[Paddy]

I'm going with "similar territory to 3rd highest previous year" rough forecasting here as for extent.  Based on PIOMAS data, I think there's still too much volume for another record... but then I know very little

[Pmt111500]

I took the highest bucket so the possible denialists on the site won't need to.

[Lord M Vader]

Like the majority of voters I believe we'll be in the range of 3,0-3,25 million km²..

//LMV

[jai mitchell]

Tropospheric sulfates are significantly reduced, no snow in Alaska in May???

we just fractured the entire CAB. . . I think 2.4 is a high-end estimate.

[plinius]

fractures are not melt. If you rip up 5% it looks pretty impressive, but it is just 5%, i.e. brings down your average albedo by about 2-3 percentage points.

[LRC1962]

fractures are not melt. If you rip up 5% it looks pretty impressive, but it is just 5%, i.e. brings down your average albedo by about 2-3 percentage points.

True, but fractures can make export easier, which count as melt. Also, fractures gives more exposure to water, which this time of year can lead to more melt. In conclusion, fractures can in the end result in more melt and therefore the more fractures at this time of year can end in greater melt by the end of the season.
Granted it did not happen the last two seasons, because everything that could go right for retaining ice happened. With higher and higher global temps do you really think that that situation will continue?

[epiphyte]

I went for 3.25 - 3.0, which is the same as I voted for extent. I think that in contrast with the past, in the era of uniform, relatively thin ice, where area/extent is concerned it will be very much all or nothing in any given region. Seems to have been the way it's gone so far, BTW...

[plinius]

The export I kind of buy, though it doesn't matter at all for the Beaufort...
Concerning contact with water, I cannot see how this is significant, since a) the surface area of an ice floe will hardly increase if you chop it into 50m size pieces, and b) the surface layer of the water is anyway cooled down to the ice temperature. Only way would be to drive up heat conduction to the depth, which is a secondary term in summer, isn't it?

fractures are not melt. If you rip up 5% it looks pretty impressive, but it is just 5%, i.e. brings down your average albedo by about 2-3 percentage points.

True, but fractures can make export easier, which count as melt. Also, fractures gives more exposure to water, which this time of year can lead to more melt. In conclusion, fractures can in the end result in more melt and therefore the more fractures at this time of year can end in greater melt by the end of the season.
Granted it did not happen the last two seasons, because everything that could go right for retaining ice happened. With higher and higher global temps do you really think that that situation will continue?

[Nick_Naylor]

I wonder whether fractured ice is more exposed to the impact of storms, by creating a better mechanism for winds to perform mechanical work on the ice and adjacent water? I have no idea how material that might be though.

[Michael Hauber]

The export I kind of buy, though it doesn't matter at all for the Beaufort...
Concerning contact with water, I cannot see how this is significant, since a) the surface area of an ice floe will hardly increase if you chop it into 50m size pieces, and b) the surface layer of the water is anyway cooled down to the ice temperature. Only way would be to drive up heat conduction to the depth, which is a secondary term in summer, isn't it?

I'm surprised that someone smart enough to know what geostrophic means and to insult those who don't, does not seem to know that chopping anything up into small pieces increases the surface area.  Chopping up an ice sheet at 2 meters thick into floes 50 meters across will increase the amount of surface area in contact with the water by 20%.  Assuming 90% of floe below water, the underside has the same roughness (i.e. ratio of surface area to that of a flat plane) as edges, and that the irregular shape of ice floes means a 30% greater perimeter than if they were circles.

One point often missed about cracking events is that the bigger the crack, the bigger the ice floes, and the thicker the ice.  Another important point is that as the cracking continues the ice sheet progresses to a jumble of different size floes that are tightly packed together.  This jumble always seems to show up as 100% concentration on ice charts, but there is significant open water within the pack which will absorb solar radiation, and to transmit this heat to the ice.  I'm not sure how much open water is in tightly packed ice floes, but the dry mass of mineral soil is about 50% of the dry mass of solid quartz, implying about 50% of the volume of mineral soil is air, so I suspect the amount could be quite substantial.

[Neven]

The insults went back and forth. If y'all stop now, you're even. There really isn't that much of a problem here.

[jai mitchell]

Only way would be to drive up heat conduction to the depth, which is a secondary term in summer, isn't it?

it helps with transport to be sure but I was suggesting that the increase in surface area by 10-20% is a major part of the seasonal melt dynamics due to convective melt effects.  Having this kind of a breakup this early in the season has the potential to be quite devastating, (if we get a good series of torch events over the next 3 weeks.

for example, the impact of the great 2012 arctic cyclone that formed on Aug 3 and lasted through the 12th.  http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=78812

See what happened to sea ice after this storm on the Charctic early august went into total sea ice devastation:

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

sure, some of it was due to warming from below, but this would have been a much temporary event, contrary to this study which I believe is faulty due to oversimplification of the geometries involved.

http://www.livescience.com/26789-arctic-cyclone-sea-ice-melt.html

[Bruce Steele]

With anomalous warm water in the Bering Sea

http://www.ospo.noaa.gov/data/sst/contour/beringst.fc.gif
 
And southerly winds over the next ~ week
 
http://www.stormsurfing.com/cgi/display.cgi?a=bering_wind

Extra heat will be moving into the Chukchi + Beaufort.  Maybe similar to 2011

Melting on the multi-year ice in the Beaufort should be enhanced IMO
 
Plenty of high SST water on the Atlantic side so Arctic Ice is being caught in a pincer
and freshwater inflows should be extra warm also.

2.75-3.00

[plinius]

@Jai, I beg to differ. Even if we drive up the surface area by a factor of 10, the question is what it would do. The main issue is to get the heat to the ice. As  that swims on top of a protecting layer of cold, quite sweet water, which will be quite in equilibrium with its ice pack, more surface area will do near nothing - as the heat flux is limited at the halocline. The only chance would be to kill the surface layer by strong turbulence or Ekman pumping, i.e. strong storm overhead.  In simple words, even if you grind your icecubes in a glass to a mush, they won't melt if you do not deliver a significant heat flow.

How do you think that Schweiger et al. oversimplified? Also, if I got that right by the way, they did actually say that it was temporary and did not do so much.

The export I kind of buy, though it doesn't matter at all for the Beaufort...
Concerning contact with water, I cannot see how this is significant, since a) the surface area of an ice floe will hardly increase if you chop it into 50m size pieces, and b) the surface layer of the water is anyway cooled down to the ice temperature. Only way would be to drive up heat conduction to the depth, which is a secondary term in summer, isn't it?

I'm surprised that someone smart enough to know what geostrophic means and to insult those who don't, does not seem to know that chopping anything up into small pieces increases the surface area.  Chopping up an ice sheet at 2 meters thick into floes 50 meters across will increase the amount of surface area in contact with the water by 20%.  Assuming 90% of floe below water, the underside has the same roughness (i.e. ratio of surface area to that of a flat plane) as edges, and that the irregular shape of ice floes means a 30% greater perimeter than if they were circles.

One point often missed about cracking events is that the bigger the crack, the bigger the ice floes, and the thicker the ice.  Another important point is that as the cracking continues the ice sheet progresses to a jumble of different size floes that are tightly packed together.  This jumble always seems to show up as 100% concentration on ice charts, but there is significant open water within the pack which will absorb solar radiation, and to transmit this heat to the ice.  I'm not sure how much open water is in tightly packed ice floes, but the dry mass of mineral soil is about 50% of the dry mass of solid quartz, implying about 50% of the volume of mineral soil is air, so I suspect the amount could be quite substantial.

[Bruce Steele]

Plinius, Although i agree the halocline does protect a vast majority of the pack from bottom melt and your argument that extra surface area of broken ice doesn't change the melting potential for bottom melt I think near the edges of the pack where warm river inflow or ice exposed to Bering or Atlantic inflow are a different matter. Broken ice near the edge of the pack should melt faster than solid ice in these areas .I have watched the ITP WHOI data long enough to see how persistent the halocline is but there are regions like the area near the Bering inflow that do see enough mixing to break down the halocline , on occasion . The Taylor columns that form over the shallow shoals as the deeper waters 
around them melt indicates there is enough surface heat and mixing to infiltrate the pack at least in some places. 
   

[jai mitchell]

one cannot simply neglect surface area in an environment of wind driven convective heat as well as solar irradiation.  I agree that the cold fresh water prevents significant undermelt.  I also understand that the breaking up of the pack also allows for increased wave height and surface mixing which contributes to increased undermelt.  My expectation is that the breakup of the pack this early in the melt season contributes significant to SURFACE melt and, of course increases surface area allow for significant increases in melt rates.

[Michael Hauber]

@Jai, I beg to differ. Even if we drive up the surface area by a factor of 10, the question is what it would do. The main issue is to get the heat to the ice. As  that swims on top of a protecting layer of cold, quite sweet water, which will be quite in equilibrium with its ice pack, more surface area will do near nothing - as the heat flux is limited at the halocline. The only chance would be to kill the surface layer by strong turbulence or Ekman pumping, i.e. strong storm overhead.  In simple words, even if you grind your icecubes in a glass to a mush, they won't melt if you do not deliver a significant heat flow.

I definitely agree that a heat flux is needed for extra melt.  The question I have is how much extra heat is added by albedo reductions for all the extra open water?  You mentioned 5%, and I think you were referring to the initial cracking event, which seems reasonable.  I suspect the number might be much higher though once the ice is reduced to a collection of irregular shaped floes packed together.  Soil can have about 50% open space which is very significant.  Ice is not soil, but I'm not sure how different it is.  Soil structure is 3 dimensional which is probably important, and I'd guess that ice floes can break off more easily to allow further compaction.  Compare soil with ice.  Note that although the white spots in the soil image are much more widely separated than the ice floes, for the soil the gaps are filled with something, presumably organic matter and/or clay, water etc.  The point is that the distribution of shapes and sizes looks roughly similar

[slow wing]

For reasons given on the companion 'Extent' thread - at  http://forum.arctic-sea-ice.net/index.php/topic,1281.msg54015.html#msg54015 - I'm going for a big melt season and  with the 2012 record low value as my central value, with large uncertainties.

So 2.24 million sq km, which is the 2.00-2.25 bin.
With one sigma uncertainties, I would guesstimate about a 2/3 probability of end up in the range 1.4-3.0 million sq km.

[Juan C. García]

Well, 9 hours to make your vote (or change it if you want to...).

[Neven]

Average prediction for all 84 votes is 2.82 million km2. Thanks for voting, everyone.