Predictions

[Vergent]

This is a thread for posting specific predictions, along with supporting reasoning/evidence. If you or someone else makes a prediction in another thread copy it and post it here. Below I have quoted a prediction that I made earlier. This way it will be easier to keep track of predictions, so proper credit(or deserved raspberries) can be given.

Neven

I think this topic should be pinned.

Vergent

r04c04:



r03c04



The Eurasian side of the CAB. This is similar to how r05c03 looked June 25 a year ago.

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r05c03.2012177.terra.500m

http://www.americanwx.com/bb/index.php/topic/35176-the-pacific-side-of-the-arctic-ice-cap-has-desinigrated/

I started a topic about it at American weather. The topic was instalocked at the request of a denialist).

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r05c03.2012227.terra.500m

Fifty days later r05c03 was open water. much of this was MYI.

The Eurasian side of the CAB is mostly FYI, it will be open ocean by Aug. 1.

Vergent

I'm sticking my neck out a mile with this one, these grids have never melted out. Last year was the worst.

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r04c04.2012255.terra.1km

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c04.2012253.terra.1km

But here is what they looked like last June:

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r04c04.2012171.terra.1km

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c04.2012164.terra.1km


For my money r04c04 and r03c04 this year look worse on 6/13, than r05c03 did in 2012 on 6/25.

As usual, I hope I am wrong.

Vergent

P.S. My daughter is graduating from UC Santa Cruz this weekend: Physical Anthropology

[Neven]

Vergent, I'll sticky this topic depending on how it develops.

Myself, I believe this year will go below 2007, but I'm not sure about 2012. However, if there is no recovery in volume in coming years and each melting season starts with the same amount of ice, it is just a question of when the year will come when the melting season has a perfect start and 2007-like atmospheric conditions (if these can be maintained in the current situation, with thin ice and everything). In that case the 2012 records will be obliterated, and ice-free conditions - below 1 million km2 SIA - could be reached.

[Artful Dodger]

Congrats, Verge. You'll be the proudest man in Santa Cruz this weekend. 

My predictions?

• Sea ice-free North Pole during Summer 2013 (<15% SIC)
• Loss of 50% of remaining MYI via advection thru Fram/Nares straits.
• another major cyclone (oh too late, that's a hind-cast...) 

[Gray-Wolf]

We all know that FY ice at 2m will melt out over an average season so even without the 'crackopalypse' event we looked to drop below 07's record low area? As it is we look to be witnessing a weather year that used to actively nurture ice levels over any summer suffering such conditions?

Over the past few years we have seen other weather events that used to 'spare' ice actively destroy it and I think we will be seeing the same again with this current 'set up'?

When coastal 'open water' becomes the norm (due to land influence from the high temps there) the central basin will have more room to 'relax' into. this will just lead to further melt at the peripheries but also alter the central basin by allowing further 'swells' to develop?

The Di-pole may also provide the impetus from the Greenland north shore ice and , much like getting a massive oil tanker moveing, once underway the likes of PAC13 will keep it in motion headed for Fram?

We may not appear to be losing ice at the rate we have become accustomed to but the ice is certainly not sat pretty and is being impacted by the weather atm?

[OldLeatherneck]

Trying to sort out how all of the unusual events this year, such as the excessive fragmenting in February & March and the long-lasting cyclone (PAC13), will affect the final numbers in September may be difficult.  We have seemly well-informed and knowledgeable commenters predicting a massive collapse, while others are beginning to question whether the record years of 2007 & 2012 will be surpassed.

That being said, I'm certain that after this season's events in the arctic, every climatologist, meteorologist and glaciologist actively studying the arctic will be hard-pressed to have all of the answers as to all of the "whats & whys" of this years dramatic events.

[frankendoodle]

I'm going to be bold this year and really stick my neck out.
1) The reason PAC13 has lasted so long is due to easier access to energy from the halocline due to a much thinner,more brittle ice cap & so close to the pole that it's not subject to the coriolis effect. 
2) Open water at 90N, I'm willing to bet my right testicle on it
3) At least 500 Gt melt for Greenland and 600-800 more likely. I'll bet lefty on that one Also, a Greenland "ice quake" may occur.
4) 2013 will beat 2012 in SIA and volume.
5) Another mass algae bloom.
6) NW Passage and Northern Sea Routes open in August.
7) Virtually iceless arctic this year is still possible.
I throwing my lot in with the "cliff jumpers" because I believe we are seeing a much more homogenous melt this year as opposed to region specific melts of years past.

[John_The_Elder]

That is more than your neck you are sticking out. You may be one of the first
" artic ice singing eunuchs "

[jdallen]

Actually... I think frankendoodle is on relatively safe ground.  I'm not as familiar with what's happening with Greenland, but I think the open water at 90 North is almost a certainty.

[crandles]

I believe we are seeing a much more homogenous melt this year as opposed to region specific melts of years past.

I guess you can say Beaufort is turning a bit turquoise and therefore may have a fair bit of melt making it thinner.

Re record year:

If we are moving towards thin ice and high area, a late large cliff certainly seems a possibility. But with low temperatures having continued past end of May, I suspect the ice volume will have moved even higher compared to last two years in the last couple of weeks. High volume as well as high area doesn't sound like a recipe for a cliff. (Well Kara, Baffin and Hudson will melt out rapidly soon but I am suggesting that would be more of a catch up in those areas than a bigger cliff than previous years which would move this year ahead.)

Is there a tendency here that whatever we see we worry about it. As opposed to recognising PIOMAS volume being a bit higher than last two years as good news?
(Similarly not much mention of Beaufort high concentration for time of year.)

[crandles]

I'm going to be bold this year and really stick my neck out.
3) At least 500 Gt melt for Greenland and 600-800 more likely. I'll bet lefty on that one Also, a Greenland "ice quake" may occur.

Only 2012 has managed 500 Gt:



That can easily be a one off due to weather rather than trend.

Melt extent seems to be behind 2012:





2012 was about to shoot up to 45% melt extent imminently. That prediction seems highly dependent on weather for next two months for such a high stake!

Seems a bit bizarre to me to express such certainty.

[BornFromTheVoid]

The first ARCUS sea ice outlook of the year has been issued, with a median prediction of 4.1 million km2.

http://www.arcus.org/search/seaiceoutlook/2013/june

[weatherintel]

A prediction of sorts - last 8 global model runs and other long range forecast tools strongly point to a hemispheric pattern change at the end of June - with surface high pressure becoming the dominant' system to occupy the arctic basin.  This evolves as the primary polar low over the arctic 'splits' into 2 major vortex's, each moving south: one over Hudson Bay and one into North Russia in about 10-12 days - followed by weakening at the start of July.  FAR too early to determine if this will remain the basic pattern for all of July - but trends and seasonal forcing all support it.

[ChrisReynolds]

I go with Neven, we'll likely beat 2007, but not 2012.

[deep octopus]

Between 2007 and 2012 for area is looking like the expected range. I still think the ice's fundamentals are horrible, but a lot time has been lost, and there's not enough open water around Beaufort or Chukchi yet to really charge up the ocean, but I do expect this to change in the next week as a high moves in and begins insolation's much delayed work. Then, we may see enough Pacific melt and then ocean heating to help clear away the debris from the PAC to sharply drop the area to just above 2012.

Volume's a bit more sticky, but I suppose it could still edge out 2012 under the assumption that a higher area relative to 2012 and lower volume would imply continuation of a thinning ice pack. The data for PIOMAS goes until the end of May, which we know was when the PAC was just emerging, so its effects (through such mechanisms as mixing the thermocline and halocline) won't be reflected until the June volumes are released at the earliest.

Ice at the North Pole really doesn't seem that farfetched of a concept anymore given the state of things now. So, sure, let's bet on that as well for fun. One thing is clear is that this has been a very weird year.

As in a Stone Temple Pilots song, "And I feel so much depends on the weather."

[ChrisReynolds]

A prediction of sorts - last 8 global model runs and other long range forecast tools strongly point to a hemispheric pattern change at the end of June - with surface high pressure becoming the dominant' system to occupy the arctic basin.  This evolves as the primary polar low over the arctic 'splits' into 2 major vortex's, each moving south: one over Hudson Bay and one into North Russia in about 10-12 days - followed by weakening at the start of July.  FAR too early to determine if this will remain the basic pattern for all of July - but trends and seasonal forcing all support it.

Thanks WeatherIntel, very useful.

It seems to me that the dominant low pressure anomaly over the Arctic Ocean is the primary reason we've seen such a slow start. However by the same token it is responsible for the unusually broken ice in Laptev, and east of the Pole. A change from July onwards could still mean 2013 beats 2007.

[frankendoodle]

That is more than your neck you are sticking out. You may be one of the first " artic ice singing eunuchs "

John: Ouch,the truth hurts! I know it's a long shot but sometimes you've got to bet big or go home. In this case, very, very big

Seems a bit bizarre to me to express such certainty.

Crandles: That graph shows a percentage of the GIS under melt, not the amount of ice mass melted let alone net ice loss (which was 630 Gt for 2012). Greenland's equilibrium line has been rising by 35 meters every year plus a lot more mining is happening on the island starting this summer which will make the ice darker on the heels of the lowest albedo ever observed. But I understand your point, seeing as the weather above Greenland has been colder than usual.

I go with Neven, we'll likely beat 2007, but not 2012.

Neven and Chris: The most probable outcome yes, but too boring for what is already such an exciting melt season. 

[Vergent]

Congrats, Verge. You'll be the proudest man in Santa Cruz this weekend. 

You have no idea.

She graduated with departmental honors, university honors, and Phi Beta Kappa(the oldest honors society in America, only 1% get invited).

That is more than your neck you are sticking out. You may be one of the first " artic ice singing eunuchs"

Is that a prediction? If so, it is nice to know that I am held to a higher standard. If you are right, at least I have finished the reproduction thing.



At any rate, r04c04 is doing a good impersonation of seasonal ice.

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/Arctic_r04c04/2012170/Arctic_r04c04.2012170.terra.250m.jpg

Last year at this time it was just beginning to break up at the top.

Vergent

[Anne]

A prediction of a record minimum area this year from a group of researchers led by Hajime Yamaguchi, a professor of ocean information systems at the University of Tokyo, along with their reasoning. It's dated 31 May.

http://www.1.k.u-tokyo.ac.jp/YKWP/2013arctic_e.html

[NeilT]

Has anyone ever looked into the Indonesia forest fires and their effect on the global climate?  Whilst I understand that they are driven, in part, by El Nino, they are also driven by man too.

I find it interesting that the two largest incidents in recent history stand just behind two huge incidents in our climate calendar.  Namely that these forest fires happened in 1997 and 2006.

If they do have an effect.  And I for one do believe that the temperature spikes in the 1939 - 45 time frame were human driven.  Then the likely result is a near miss for extent this year and the swansong for Arctic summer ice in 2014.

It's something I've been waiting a while to test out.  It depends no how long the Indonesians let the fires go.  In 1997 the fires spanned more than half a year and carried on into 1998.  This year they are water bombing them, but the peat has almost certainly ignited.  During the Russian fires, when the peat ignited, they had to flood the areas again in order to put it out.  Nothing else would do.

It will be interesting to follow anyway.

[TerryM]

A prediction of a record minimum area this year from a group of researchers led by Hajime Yamaguchi, a professor of ocean information systems at the University of Tokyo, along with their reasoning. It's dated 31 May.

http://www.1.k.u-tokyo.ac.jp/YKWP/2013arctic_e.html

Very nice find Anne!


Their 'animation of particles' (fig.7) doesn't appear to be allowing for advection in either Nares Strait or the CAA. Is it possible to somehow step through the various animations?


Terry

[Stephen]

Has anyone ever looked into the Indonesia forest fires and their effect on the global climate?  Whilst I understand that they are driven, in part, by El Nino, they are also driven by man too.

I find it interesting that the two largest incidents in recent history stand just behind two huge incidents in our climate calendar.  Namely that these forest fires happened in 1997 and 2006.

If they do have an effect.  And I for one do believe that the temperature spikes in the 1939 - 45 time frame were human driven.  Then the likely result is a near miss for extent this year and the swansong for Arctic summer ice in 2014.

It's something I've been waiting a while to test out.  It depends no how long the Indonesians let the fires go.  In 1997 the fires spanned more than half a year and carried on into 1998.  This year they are water bombing them, but the peat has almost certainly ignited.  During the Russian fires, when the peat ignited, they had to flood the areas again in order to put it out.  Nothing else would do.

It will be interesting to follow anyway.

The current Indonesian fires are definitely burning peat. Its over swampy ground on the eastern central coast of the island, which is why Singapore is so badly affected.

I saw a news item last night and the reporter said there was a bed of peat about 1 metre thick which had ignited.  I cannot imagine the Indonesians have the resources to "Flood them out"

[jdallen]

Bad, very bad. That peat is their land's fertility. They are burning their food production.

For a nation with so little arable land, and such a large population, it seems a recipe for self destruction.

[slow wing]

From looking at NASA's EOSDIS Worldview graphic, e.g.

http://earthdata.nasa.gov/labs/worldview/?map=-1257600,-35200,-115840,833152&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines&time=2013-07-01&switch=arctic

and the University of Bremen AMSR2 sea ice concentration graphic

http://iup.physik.uni-bremen.de:8084/amsr2/arctic_AMSR2_nic.png

I predict a big hole in the Arctic ice, hundreds of km on a side (say, 250 km x 500 km), and extending to within about two degrees from the North Pole, to have formed by the end of this month, July.

We will find out soon enough, anyway. 

[ananthapriya]

Bleeding thing aside, this is still pretty good.

[slow wing]

From looking at NASA's EOSDIS Worldview graphic, e.g.

http://earthdata.nasa.gov/labs/worldview/?map=-1257600,-35200,-115840,833152&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines&time=2013-07-01&switch=arctic

and the University of Bremen AMSR2 sea ice concentration graphic

http://iup.physik.uni-bremen.de:8084/amsr2/arctic_AMSR2_nic.png

I predict a big hole in the Arctic ice, hundreds of km on a side (say, 250 km x 500 km), and extending to within about two degrees from the North Pole, to have formed by the end of this month, July.

We will find out soon enough, anyway. 

Time is up and I really can't claim success with that prediction. At 90 degrees East, the ice still hasn't made up its mind whether it is going to be a fully fledged hole...




Is that proto-hole part of the infamous "Laptev bite"?

[pikaia]

Some of those pixels are dark blue, ie <10%, so genuine open water, albeit in small amounts.

[ChrisReynolds]

Slow Wing,

This is a puzzle that's bugged me for years. Why don't large holes in the pack just open up? Given the fractured state at the end of every summer for years now - why doesn't the whole pack just float out to fill the whole ocean?

Why does it stick together?

Here's a WAG.

There's a phenomenon in physics motion whereby two plates can be drawn together by the 'force' of particles outside the plates being 'greater' than the force between the plates. Does wave action given the longer fetches of open water around the pack cause something similar to happen.

In short - is the pack always destined to fill in holes and stick together?

[Vergent]

Slow Wing,

This is a puzzle that's bugged me for years. Why don't large holes in the pack just open up? Given the fractured state at the end of every summer for years now - why doesn't the whole pack just float out to fill the whole ocean?

Why does it stick together?

Here's a WAG.

There's a phenomenon in physics motion whereby two plates can be drawn together by the 'force' of particles outside the plates being 'greater' than the force between the plates. Does wave action given the longer fetches of open water around the pack cause something similar to happen.

In short - is the pack always destined to fill in holes and stick together?

Chris,

It's the same reason that warm currents flow north. Because it is down hill to the pole. This is due to the rotation of the earth and the cold dense outflow from the Fram(and the restricted inflow due to the low salinity lens. When a storm spreads it out, gravity pulls it back.

Vergent

Edit: Its also attracted to Greenland. Also, ice heading South will accelerate to the West. That is why the ice clings to Greenland's east coast.

[Peter Ellis]

Inertia?  Why would it spread out without a force acting on it?  When there's a divergent wind field, it diverges.  When there's a convergent one, it converges.  When there isn't, it stays still.  Ice is heavy, and it's moving through a fluid with a lot of frictional resistance. It takes a hell of a lot of energy to move it: it's not just going to float apart for no reason.

[Vergent]

Inertia?  Why would it spread out without a force acting on it?  When there's a divergent wind field, it diverges.  When there's a convergent one, it converges.  When there isn't, it stays still.  Ice is heavy, and it's moving through a fluid with a lot of frictional resistance. It takes a hell of a lot of energy to move it: it's not just going to float apart for no reason.

Peter,

The normal arctic cell air motion would push the ice apart, if the gravitational forces pushing toward the pole were not greater. Viscosity(not friction)is the proper term for liquids. Water is a low viscosity liquid. It is quite easy to move a 10 ton boat, a sustained push with a finger is all that is needed. Jack Lalane swam pulling 70 boats carrying 70 people for a mile on his 70th birthday.

xxhttp://www.youtube.com/watch?v=skRb-oND3qAxx

Remove the xs to watch

Vergent

[Dromicosuchus]

Whoa, wait a minute.  Vergent, when you say it's "downhill to the pole," you aren't speaking literally, are you?  The geoid has long since compensated for the effects of the Earth's rotation on the local perceived gravitational strength, and even if it hadn't, the oceans would have bulged out as needed to compensate.  The circulation cells in the atmosphere and ocean are contained by gravity, sure, but their overall flow is a result of the difference in insolation between pole and equator.

...I feel like I'm massively (and insultingly) misunderstanding what you're saying.  If that's the case, I'm very sorry; no offense is meant.

[slow wing]

Chris, that is a good question about why the remaining ice doesn't just spread out to fill the whole ocean.

  My guess is that it is because there is a prevailing direction or pattern for the wind + currents that move the ice. The ice tends to pile up against the northern coast of Canada. (And some of it squirts out the Fram Strait etc.)

  From time to time the ice will locally be moved in the opposite direction to the prevailing one, and so will spread out. Also, sometimes it will be pushed apart by low pressure systems and sometimes compacted by highs. But the spatial extent and duration of these systems is not enough for the ice to be spread out all the way across the Arctic Ocean. Instead, the ice will tend to be pushed back in the prevailing direction once that local system has died away.

  Another possible reason during the melt season is that the ice at the edges is more susceptible to melt than that in the pack, so it is being eaten away even as it is spreading.

[Vergent]

Whoa, wait a minute.  Vergent, when you say it's "downhill to the pole," you aren't speaking literally, are you?  The geoid has long since compensated for the effects of the Earth's rotation on the local perceived gravitational strength, and even if it hadn't, the oceans would have bulged out as needed to compensate.  The circulation cells in the atmosphere and ocean are contained by gravity, sure, but their overall flow is a result of the difference in insolation between pole and equator.

...I feel like I'm massively (and insultingly) misunderstanding what you're saying.  If that's the case, I'm very sorry; no offense is meant.

Yes I mean it literally. It is downhill toward the pole.

Vergent

edit:SSH = Sea surface height

[Vergent]

Its true globally.

Vergent

[Artful Dodger]

Its true globally.

Hi Verge,

The first science result from CryoSat2 radar data was this map of 'ocean dynamic topography', which is the height of the water relative to the geoid, released by ESA on Jan 25, 2011:

It shows that the sea surface height is about 80 cm above that of the East Greenland sea near Svalbard. The slight downhill gradient from the Bering Strait to Fram Strait is largely responsible for the Transpolar Drift current.

[Vergent]

Lodger,

Yes, and if you look out to where the ice margin has been of late, the downward vector is toward the pole. The exceptions proves the rule. In the ESAS the ice does tend to spread out toward the coast, and older ice tends to slide into the Beaufort and melt. Both are consistent with the topography.

This is why warm currents flow poleward and cold currents toward the equator.

Vergent

[ChrisReynolds]

I don't buy the 'downhill' argument because the gradients in SSH are largely set up by the wind. For example the hump in Beaufort is due to the climatological Beaufort High. High pressure causes convergent flow.

I too have pondered the climatological winds keeping ice together, but you do get years that are the reverse of climatology. Here the issue of ice melting at the ice edge comes in, and I think this is a good point.

Inertia is also a good point, but once again you can have summers with radically different atmospheric patterns and the ice pack does move in response. Yet even with low concentration regions within the pack; they don't seem to open up to open water. Furthermore taking a region of low concentration with floes of different sizes, why doesn't the wind preferentially move the smaller floes out from the larger? Maybe it does but the smaller floes melt more quickly once in warmer open waters.

It still strikes me as an interesting oddity that the pack doesn't disperse more. I think we're all seeing parts of the mechanisms, like the proverbial blind men and the elephant.

Vergent, sorry for derailing your thread.

[helorime]

Howabout some simple chemistry.  Liquid water can make and break hydrogen bonds more easily than can occur in crystalline forms.  So perhaps the dynamic forces of liquid water nd it's resulting cohesiveness just tend to keep the liquid together and somewhat exclude the ice... not quite as severely as with hydrophobic interactions as in oil and water which causes oil to pool, but a much milder version of a somewhat similar phenomenon.

[seattlerocks]

Hi I just wanted to make some comments pertaining to Physics.
- Ice density is very close to water density, salty or not. So the inertia of a floating ice block is about the same as the water that it displaces.
- Viscosity and friction are two very different things. The first is a property of the fluid and the second is an observed force. Friction can be used for solids and fluids, allthough for this case you may hear the word 'drag' more frequently, even 'resistance'.
- Water viscosity can be considered small (well, define small) but the drag forces that halt an oceanic flow are enhanced by turbulence, the resulting forces being tens, hundred times greater than if the flow was laminar.

Said so, my feeling is that the  ice cap when it is broken in pieces just does the same as what the water surface would do in the absence of the ice, with the diference that ice is an ocean-atmosphere interface that is less affected by winds given its smooth, wave-absent solid surface. Now, given the ocean currents configuration, there are several stagnation regions in the oceans, and this may just well be one of them. A storm comes, it diverges, another thing comes, it is compacted. But overall, the thing stays there forever, maybe just some rotation. The ice just flows with it, or within it, not doing much except for slowing down action.

[johnm33]

Chris There's something true in your comment on the physics of wave motion on ice, big ships don't parallel park for this very reason.

[slow wing]

Again in the spirit of this thread, I predict record Arctic sea ice losses for August in all of NSIDC extent, Cryosphere Today area and PIOMAS volume. (Does 2012 hold the current records?)


That even takes into account the slow start to August, particularly in CT area. I just think there is a lot of ice that is ready to go, on the Eastern side in particular.

[ChrisReynolds]

Slow Wing,


That's CT Area losses over August for past years. To quote from my recent blog post:

If we take the greatest July losses as being around 1.8M km^2 then using current CT Area and assuming this year will be a high end loss the CT Area at minimum would be around 3.0M km^2, in the same ball park as 2007 or 2011. But to reach 2012's area at minimum would need a loss of around 2.6M km^2, this has never happened, not by a long way, as the above graph shows.

John,
Thanks that's a much better example.

[Nightvid Cole]

I don't buy the 'downhill' argument because the gradients in SSH are largely set up by the wind. For example the hump in Beaufort is due to the climatological Beaufort High. High pressure causes convergent flow.

I too have pondered the climatological winds keeping ice together, but you do get years that are the reverse of climatology. Here the issue of ice melting at the ice edge comes in, and I think this is a good point.

Inertia is also a good point, but once again you can have summers with radically different atmospheric patterns and the ice pack does move in response. Yet even with low concentration regions within the pack; they don't seem to open up to open water. Furthermore taking a region of low concentration with floes of different sizes, why doesn't the wind preferentially move the smaller floes out from the larger? Maybe it does but the smaller floes melt more quickly once in warmer open waters.

It still strikes me as an interesting oddity that the pack doesn't disperse more. I think we're all seeing parts of the mechanisms, like the proverbial blind men and the elephant.

Vergent, sorry for derailing your thread.

But they do open up in some cases, the most prominent example perhaps being 2006:

http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2006/sep/asi-n6250-20060902-v5_nic.png

[Vergent]

Chris,

Your argument is only valid if there is a rate constant involved in area loss. Historically, this was true. But, 2012 was a game changer. Prior to that, in situ melting was not a significant factor. Now, it is a huge factor. Ice melts out in parallel, not serially from the edge. Basically, in situ melting the following equation becomes true.

Top melt + Bottom melt = Spring thickness

Topaz4 seem to think this is about to happen over a vast area.

Vergent

[Vergent]

The Cheshire Cat comes to mind.

Vergent

edit:



2012 for comparison.

edit:



If ya aint got nothing, you go nothing to lose. - Bob Dylan



V

[Dromicosuchus]

...Oh my wocks and hoop soons, Vergent, that's terrifying.  It's like a blender was taken to the ice.  And as I recall, that model isn't generally that far off from the truth--certainly not in broad-stroke details like that.

Well.  Things should be getting extraordinarily interesting in a week or so, then.  The sea ice thickness graph, particularly, is just...Augh.  It's like pond scum swirling around in a disturbed lake surface.

[danp]

What are the dates of those two Topaz plots from 2012 (i.e., are they the model's current best guess for what the actual thickness was at the time?)  I am not familiar with Topaz and wondering if it has a tendency e.g. to be aggressive about melt predictions, in which case it would be interesting to see how the modeled predictions for those 2012 dates changed as the actual dates approached.

Basically I find that comparison as shocking as Dromicosuchus and so am looking about for some reason for skepticism.

[Vergent]

I refrained from using the changeable scale feature to hypothetically remove an additional 50cm from the thickness, or melt any ice below 50% concentration. Or, gasp, combine the two.

The raw output was alarming enough. It may have faulty temp layers at depth, but those are only effecting that polynya near the CAA.

Vergent

[Neven]

My conclusion two years ago was to not put too much trust in TOPAZ (even though one of the people behind it was nice enough to let me interview him), but I don't know what they did with the model since then.

[Vergent]

Dan,

I believe them to be analysis hindcasts. They should be bang on for extent, but still iffy for thickness. My recollection is that compared to The Healy aloft cam, they look a little too thick. But, the models count melt ponds as ice, so looks can be deceiving(a broken piece of melt pond may be 1/2 m thick but, before being broken, was counted properly as 1 1/2m).

Vergent