The 2018 melting season

[NeilT]

I must admit I don't think it was boring at all.  Incredibly interesting the way it has both melted and survived this year.

High's or not, we're past the solstice and, in August, past the strongest melting sun, if not the greatest heat.

I still feel that to suddenly turn around and make a radical move downwards, the weather is going to have to play quite a large part.

Whatever else it is going to be very interesting.  I see the Bremen concentration now showing a firm barrier on the Atlantic side right round to the Laptev.  It will be interesting to see if that really is or whether the sensors are deluded.

The NW passage is showing extensive melt again, but time will tell whether that is surface or if the ice is truly going to vanish this time.

The ESS is falling back, slowly.

The Beaufort is collapsing in the centre but still has a long way to go before it clears out.

About 6 weeks of melting left.

Now it is a clock thing.

[Frivolousz21]

The gfs is pretty nasty.

Still plenty of solar the next 2-3 weeks to really dent things. 

[gerontocrat]

A lot of comment about how this year the Arctic weather is so much like last year - cool and cloudy.

BUT - For the last 2 (2 1/2?) months there has been a big fat high over Western Europe and the Eastern Atlantic. (This did not happen in 2017). As a result for 2+ months warmish wettish air and presumably surface ocean water from the Atlantic lows have been sent up the Norwegian and Barents seas into the Arctic. As far as the UK is concerned, I think you have to go back to 1976 for such a long period of domination by a blocking high.

Surely that must have some effect? Atlantification ? the Kara cliff and Laptev persistent area loss?

ps:- Attached is NSIDC sea ice concentration image. Even if melt ponds are confusing the sensor, there is not a lot of solid stuff left.

[jdallen]

The gfs is pretty nasty.

Still plenty of solar the next 2-3 weeks to really dent things.

Yes, especially at lower latitude, like the Beaufort, CAA, Chukchi and ESS.

Especially as the forecast favors high pressure over the Pacific side.

Clear weather could strip 4CM+ a day off the top of ice, much of which is only 50-75CM thick.  And then there's the bottom melt.

Yes, there's plenty of room for some serious dents.

[bbr2314]

2018 is approaching the state of the Titanic when the stern began to rise above the water. Beforehand, the sinking was slow and steady. As momentum built, it only took another 30 minutes to split in two and sink. We are at about the two hour mark. (LINK: https://youtu.be/rs9w5bgtJC8?t=2h1m29s)

The splitting analogy is not horrible either given the situation in the ESS. HYCOM and Copernicus both show the shore ice holding fast through 8/4.

Beaufort and Chukchi are about to disappear. The Laptev is also about to begin taking huge bites out of the CAB. The ATL front is failing, slowly but surely. This will matter most because it appears that the huge oceanic heat anomalies to its south will prevent an early refreeze (which would be our only saving grace).

Everything is now happening simultaneously. The latest Copernicus output for 8/4 is very troubling. What happens if / when we get an August GAC? We are approaching 2012's state *without* needing a late July / early August +++cyclone.   

7/27 -> 8/4 concentration below. Anything under yellow will be gone in another week (8/11). The cliff we are now seeing may become even sharper.

[Thomas Barlow]

Lincoln Sea is mush.

26-07-2018 - Sentinel Playground.

[slow wing]

Wow! In the Bremen ASI false color maps, the ice seems to have taken a pounding for the second day in a row! Just look at that deterioration in the Beaufort Sea and ESS!

I expected a 'bounce back' today, but no. Still expecting one tomorrow. But once areas go green they are usually in a poor state already.

Gif will need a click to start..

[Frivolousz21]

No that is very aligned with the last cryosat reading of where the thinnest ice was.

Amsr2 also confirms this.

There was a huge area of ice that only refroze to 1-1.5M over the Pacific side of the arctic.

The weather has been no where near bad enough historically for that area to be this disintegrated this summer.

If we do see a dipole anomaly generally the next two weeks.

A huge chunk of blue ocean is opening up

[GoSouthYoungins]

The weather has been no where near bad enough historically for that area to be this disintegrated this summer.

If we do see a dipole anomaly generally the next two weeks.

A huge chunk of blue ocean is opening up

Quite the change of heart. Yes the weather has been favorable, but the progressive march of increasingly unfavorable baseline conditions is overwhelming.

[jdallen]

No that is very aligned with the last cryosat reading of where the thinnest ice was.

Amsr2 also confirms this.

There was a huge area of ice that only refroze to 1-1.5M over the Pacific side of the arctic.

The weather has been no where near bad enough historically for that area to be this disintegrated this summer.

If we do see a dipole anomaly generally the next two weeks.

A huge chunk of blue ocean is opening up

May not even need a dipole.

It maybe time to pay the piper.

The ice in the ESS previously got hit hard by heat blowing off of Siberia.  The ice now looks much like the Kara did about 3 weeks ago.  The Beaufort and what remains of the Chukchi are as bad or worse.  There's about 2 million KM2 of soup in this image.  Kara from July 4th added for contrast.

[Aluminium]

July 18-26.

[uniquorn]

Today's ecmwf weather from windy.

[F.Tnioli]

...
About 6 weeks of melting left.

Now it is a clock thing.

Don't we have the (slow) trend of melting seasons lasting longer and longer as years go by? And, don't you think that this year, which in particular is marked by high temperature records in many polar and sub-polar locations, has enough heat stored around to possibly contribute greatly to above mentioned trend? You say it's 6 weeks of melt left, but me, i wouldn't be surprised if it would turn out to be about 7 or even 8 weeks left, this time. I wonder if it's just me, though...

[gerontocrat]

Don't we have the (slow) trend of melting seasons lasting longer and longer as years go by?

Not really - graph attached (JAXA from 2004 to 2017 - Jaxa ver.1 data file hasn't got all the years back to 1979 - that shows a bit more of a trend)

[RikW]

No that is very aligned with the last cryosat reading of where the thinnest ice was.

Amsr2 also confirms this.

There was a huge area of ice that only refroze to 1-1.5M over the Pacific side of the arctic.

The weather has been no where near bad enough historically for that area to be this disintegrated this summer.

If we do see a dipole anomaly generally the next two weeks.

A huge chunk of blue ocean is opening up

May not even need a dipole.

It maybe time to pay the piper.

The ice in the ESS previously got hit hard by heat blowing off of Siberia.  The ice now looks much like the Kara did about 3 weeks ago.  The Beaufort and what remains of the Chukchi are as bad or worse.  There's about 2 million KM2 of soup in this image.  Kara from July 4th added for contrast.

I also just checked worldview and my mouth felt open at the dramatic state of the ice. The pacific side, and especially beaufort is looking far worse then a lot of the other years around september 13th.

Based on this shot I'm willing to bet that that all periferal seas except CAA will be melted out for at least 95% at the end of the melt season and that even that the area outside 85 degrees will also be mostly gone

I've just drawn a map what i think will be the region:

[uniquorn]

I suspect there will be more dispersion before extent drops significantly
(cue more century drops )

Worldview pacific side jul25-27

[pearscot]

I am as surprised as everyone else by the quick deterioration of the ice. It looks like a thin mush in a lot of parts. I had not expected this to occur, especially so late in the melting season. I wonder now if this warm summer will extend the season an extra week or even a few days. So much more to understand with it.

[uniquorn]

A comparison of clearest days of the part of the CAB close to jul26 from 2012-2018.
AMSR2-UHH ice concentration, Worldview terra/modis true color
ASCAT(many cloud/weather effects), Worldview enhanced

cropped out the amsr2 date by mistake

[jdallen]

I am as surprised as everyone else by the quick deterioration of the ice. ...

We've had hints.  Thinking back to the refreeze, the regions now disintegrating were late to freeze, and suffered heavily from persistent imports of heat through the Bering.  This was reflected in some of the thickness maps, but others consistently reported that the ice was probably a meter or more thicker than it actually was.

Roll forward to today.  Speaking in approximations, in recent years (2015 to present) volume at peak is running around 21,000 KM3 at max.  If you take the most recent maximum extent - about 14,000,000 KM2, we end up with an average ice thickness of about 1.5 meters.

Looking earlier - here I'm thinking of the old regime - 1980-89, the extent isn't particularly greater - only about 16,000,000 KM2, but typical average volume is much higher - on the order of 31,000 KM3, which gives us at that time a typical average thickness of around 1.93 - call it almost 2 meters.

The difference between the two - 50 centimeters - is very key, because the drop in thickness and volume means that we've passed a key threshold:  the typical energy taken up during the melt season in the Arctic is almost enough to melt out all volume.  The number here, approximating from Jim Pettit's graphs examining typical volume lost during the melt season, divided by max area works out to be about 1.3 meters of melt.

Obviously that melt isn't distributed evenly, nor is ice thickness.  However, it does mean that regions which do not pass that 1.3 meter thickness during the refreeze are now at serious risk.  It will take extraordinarily favorable conditions for ice retention to prevent an *average* melt from melting out the areas where this is true.

I think that's what we are seeing here, and elsewhere, such as the interior of the CAB where we've been having surprising losses in area.  Interstitial ice formed in leads during the season which did not have time to thicken sufficiently past that 1.3 meter threshold is disappearing.

We are definitely in a new regime.

[RoxTheGeologist]

I am as surprised as everyone else by the quick deterioration of the ice. It looks like a thin mush in a lot of parts. I had not expected this to occur, especially so late in the melting season. I wonder now if this warm summer will extend the season an extra week or even a few days. So much more to understand with it.

Yes, agreed. We all knew that the Bering and Chukchi had an anomalously warm winter with late freeze up and early melt. I thought that we would see a gradual reduction with anomalously low extent throughout the melting season, not for it (Chukchi extent) to stall and then for it all to go 'poof' over 10 days (and counting).

[Jontenoy]

JDAllen wrote: The difference between the two - 50 centimeters - is very key, because the drop in thickness and volume means that we've passed a key threshold:  the typical energy taken up during the melt season in the Arctic is almost enough to melt out all volume.

This suggests that volume is the key and I agree as volume is more important than area. Although, surface area is critical (a pancake melts faster than a ball for same volume). 
The calculation of ".... enough energy to melt 1.3 metres " is so important it needs to be accurately checked

[Shared Humanity]

...
Does a couple of months where it is neither melting nor freezing count as Melting Season, or as Freezing Season?

Both, because it's not "neither melting nor freezing", - in reality is "both melting and freezing". Simultaneously. So, those kinds of seasons overlap. You use either one, other, or both terms depending on which process(es), area(s) and date(s) you talk about.

I think that SIE is a poor metric for defining freeze season and melt season. Volume would be a better metric as the refreeze in the CAB would cause volume gain there outweigh the continued drop in extent as thin dispersed ice melting in the periphery has less of an impact on volume. Unfortunately, I don't think we can track volume in such a way as to see when it begins to grow.

[Shared Humanity]

Lincoln Sea is mush.

26-07-2018 - Sentinel Playground.

That image is amazing. Lincoln Sea use to be where some of the thickest ice hung out.

[bairgon]

Reviewing the ice on the Pacific side over the last week or so, it seemed to have suffered significant damage in the images from the 19th and 22nd of July. Checking back in Nullschool shows that a lot of heat was being brought through from the Pacific on those days.

Looking ahead shows some more coming through on the 29th/30th, but also predictions for a lot of heat on the Atlantic side. The image below is for August 1st, 13:00 UTC.

Given the state of the ice in the Lincoln sea (as posted up-thread) this could have a similar effect.

[Shared Humanity]

We are definitely in a new regime.

I agree. Highly fragmented and dispersed MYI glued together by relatively thin FYI due to increasingly warmer winters. The days of thick, ridged, MYI slabs that withstand heat and mechanical forces are gone forever.

[Dharma Rupa]

...
Does a couple of months where it is neither melting nor freezing count as Melting Season, or as Freezing Season?

Both, because it's not "neither melting nor freezing", - in reality is "both melting and freezing". Simultaneously. So, those kinds of seasons overlap. You use either one, other, or both terms depending on which process(es), area(s) and date(s) you talk about.

I think that SIE is a poor metric for defining freeze season and melt season. Volume would be a better metric as the refreeze in the CAB would cause volume gain there outweigh the continued drop in extent as thin dispersed ice melting in the periphery has less of an impact on volume. Unfortunately, I don't think we can track volume in such a way as to see when it begins to grow.

I agree with you both on why Volume would be a better metric and why we can't really use it.  What I don't know is that the refreeze volume in the CAB would be earlier to such a degree that it would overwhelm the periphery.  I can think of reasons you may be right and reasons you may be wrong.  In particular, thicker ice tends to thicken slower.

[FishOutofWater]

At the end of the last melting season ice was unusually thick on the Siberian side and unusually thin on the Chukchi, Alaskan and Canadian side. Although the weather has been favorable for ice retention on the American side, there was less ice to melt. Meanwhile the heat advected off of Siberia devastated the ice on the Siberian side. That's leading to a stunning late season extent loss.

[Ned W]

Here is a comparison of 2015 to 2018, during the past three days (24-26 July), in terms of the areal distribution of concentration:



It's a comparison of the histograms of the NSIDC concentration data, averaged over the three-day period, for both years.  I've grayed out the under-15% zone that doesn't count towards extent.

The median concentration for this period of 2015 was 62.4; the median concentration in 2018 was 65.8.  This slightly understates the difference, as those numbers are based on pixels with >0% ice, and 2018 has slightly more extent than 2015 did at this time.

[gerontocrat]

Unfortunately, I don't think we can track volume in such a way as to see when it begins to grow.

Yes you can. Data is made available by the Polar Science Center (daily and monthly) each month afterthey produce the monthly PIOMAS update. 
http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/data/

Wipneus also provides a link (where I forget).

I have never got around to organising it as a mirror of NSIDC Extent and Area data. Maybe next month. But I did a simple graph of daily volumes and 365 day calendar averages just for amusement.

[Frivolousz21]

Thats pretty thin going into May.

[bbr2314]

Cue the band! I have a feeling the resilience of the CAA will force more heat to its NE vs. 2012's scenario (and there is still way more ice in HB / Baffin. This will probably all melt, but it will also continue forcing more heat furthest N / into the ATL sector). That means the NE ATL quadrant will take more brunt while the CAA / CAB adjacencies will be more sheltered. The net result may be a similar outcome in overall area.

[gerontocrat]

...and there is still way more ice in HB / Baffin.

Not really much ice left in either sea. Area almost down to 2010's average.

[oren]

I am as surprised as everyone else by the quick deterioration of the ice. It looks like a thin mush in a lot of parts. I had not expected this to occur, especially so late in the melting season. I wonder now if this warm summer will extend the season an extra week or even a few days. So much more to understand with it.

Yes, agreed. We all knew that the Bering and Chukchi had an anomalously warm winter with late freeze up and early melt. I thought that we would see a gradual reduction with anomalously low extent throughout the melting season, not for it to Chukchi extent to stall and then for it all to go 'poof' over 10 days (and counting).

I remind again the line/arc of thick old ice that stretched all the way from the CAA to the Chukchi and beyond during winter and spring, as shown on many of A-Team's posts. I believe it delayed melt for quite a while, but once it broke down all the rest was slush.

[Michael Hauber]

Beaufort and Chukchi is definitely in bad shape, comparable to 2012 and about to get slaughtered.  Siberian (western half) and Laptev is much better and won't lose so much.  I don't think we will seriously challenge 2012.

[bbr2314]

I am as surprised as everyone else by the quick deterioration of the ice. It looks like a thin mush in a lot of parts. I had not expected this to occur, especially so late in the melting season. I wonder now if this warm summer will extend the season an extra week or even a few days. So much more to understand with it.

Yes, agreed. We all knew that the Bering and Chukchi had an anomalously warm winter with late freeze up and early melt. I thought that we would see a gradual reduction with anomalously low extent throughout the melting season, not for it to Chukchi extent to stall and then for it all to go 'poof' over 10 days (and counting).

I remind again the line/arc of thick old ice that stretched all the way from the CAA to the Chukchi and beyond during winter and spring, as shown on many of A-Team's posts. I believe it delayed melt for quite a while, but once it broke down all the rest was slush.

Indeed. This year the "arc" ended up stuck to Russia in the ESS. Partially why this is unfolding so quickly.

[Darvince]

Here is a comparison of 2015 to 2018, during the past three days (24-26 July),

How high is the 100% concentration bin for this year?

[jdallen]

Beaufort and Chukchi is definitely in bad shape, comparable to 2012 and about to get slaughtered.  Siberian (western half) e6and Laptev is much better and won't lose so much.  I don't think we will seriously challenge 2012.

I'm not sure I can wholeheartedly agree with the "much better" judgement.  What I can see has no structure in the extent, has lots of small area of open water which suggests it's fragmented into millions of small floes, and bears considerable resemblance to the ice in my 7.4.2018 snapshot of the Kara.  I think the best that can be said is it's more compact.

[GoSouthYoungins]

Circumnavigation of Greenland looks like in will be possible by the end of August.

The entire CAA and Greenland side could "lift off". It would take a few days of particular weather, but the underlying condition will be there. The old thick stuff finished its disintegration last year, and now all sorts of previously unthinkable things are possible.

[uniquorn]

I remind again the line/arc of thick old ice that stretched all the way from the CAA to the Chukchi and beyond during winter and spring, as shown on many of A-Team's posts. I believe it delayed melt for quite a while, but once it broke down all the rest was slush.

Indeed. This year the "arc" ended up stuck to Russia in the ESS. Partially why this is unfolding so quickly.

I am pretty sure that the 'arc' is not stuck to Russia in the ESS
edit:took out some repeat quotes

[Frivolousz21]

Bremen amsr2 images are going to be decently clear the next 3-4 days.

We will get a great snapshot of the ice pack.

It appears a similar size area of solid contiguous flows for the most part comparable to 2007, 2015, 2016, and 2017 is protected well.

Because of the inherently thin ice over the Pacific side its clear heat has penetrated above and below the ice.  Once  that large area abruptly opened up with miles and miles of open water, between large groups of floes waves and some form of convective overturning allowed solid mixing of heat into the upper ocean layer.

If heat only penetrates a few meters its all the same.

Every clear moment with the surface above -1c saw a proportionate level of warming and melting of ice comparative to the ambient temperature.

The combo of fog, sun, and high vapor content is lethal.

A surge of moisture rocked the Pacific side and it collapsed in one week.

Now waves will be overturning and crushing ice floes.

Game over.

Ice loss will slow a bit from fresh cold water around the ice.

But the sun is returning with a massive thermal seasonal peak of heat from the NA continent and NPAC.

Also



EPIC HEAT IS ROCKING THE BARENTS THEN MODELS SHOW A LONG WIND FETCH + SUN  OVER THE ATLANTIC SIDE.

THIS WILL CRIPPLE THE ICE NEAR THE LAPTEV AND LOSOMOV RIDGE UP TOWARDS THE POLE AND NE lincoln sea.

A downslope wind off GIS parallel to the east coast of gis is brutal to the ice along the Atlantic edge.


THE WIND + solar input will prevent THE WARM WATER COMING NORTH FROM NATURALLY MIXING DOWN.

THE FRICTION FROM WIND ENERGY WILL CAUSE THE SURFACE CURRENT TO BE MOVING TO FAST TO MIX UNDER THE COLD POOL.

THE HEAT WILL ESSENTIALLY ROLL OVER THE COLD POOL PUSHING IT BACK TOWARDS THE ICE PACK.

EVERY INCH OF WATER SURFACE AREA WARM WATER INTRUDES TOWARDS THE POLE WITH A BACKED LONG FETCH ALL THE WAY TO SCANDINAVIA BLOWING OVER ALREADY HISTORICALLY WARM WATER COULD BE HISTORICAL.

The shitty ice is clear on jaxa. Can't wait to see modis and amsr2-the next 6 hours.


The steady dipole brings sun but creates a dry air dome.

This volatile anomalous pattern is cloudy but brings epic moisture laden surface warmth.

WAA with fog and surface few points around 33-34C is ice ending boom.

The only other ice crippler like that is an epic direct waa scheme from land surface heating.

[Eco-Author]

Because of the inherently thin ice over the Pacific side its clear heat has penetrated above and below the ice.  Once  that large area abruptly opened up with miles and miles of open water, between large groups of floes waves and some form of convective overturning allowed solid mixing of heat into the upper ocean layer.

Sounds like you are referring to a Kelvin wave/bubble.

[Frivolousz21]

I'm fucking blown away.

But how??

[jdallen]

Bremen amsr2 images are going to be decently clear the next 3-4 days.
<snippage>
EPIC HEAT IS ROCKING THE BARENTS THEN MODELS SHOW A LONG WIND FETCH + SUN  OVER THE ATLANTIC SIDE.
<more snippage>
THE HEAT WILL ESSENTIALLY ROLL OVER THE COLD POOL PUSHING IT BACK TOWARDS THE ICE PACK.
<still more snippage>

I was just looking at those climate reanalyzer moisture forecasts wondering if I should post them.

Thanks for saving me time

We may be in for a helluva ride with those blasts of heat, latent and sensible, that are going to roar across the Barent's into the pack, combined with whats playing out on the Pacific side.

[slow wing]

Yes, the deterioration of the ice pack over the past 3 days has been jaw-dropping!

Click to animate...

[miki]

I'm fucking blown away.

But how??

I had called it the great spreading, some time ago. I guess, without real volume, it was "fake ice". A little stir, some warm water. And now the moisture / heat. Heck!

[slow wing]

Worldview visual confirmation is starting to come in for 2018-07-28.

Here is:
1) a screenshot of most of the area showing by now from TERRA satellite - roughly the Pacific side of the Arctic; and
2) a movie of the 10-day interval from 2018-07-18 to 28 for a zoomed-in region well into the ice pack but where the concentration isn't all that high - around 180 degrees longitude & latitude 80 degrees North & maybe ~180 km x 130 km (just a guess to give an idea of the scale). The approximate rectangle of the frame is also sketched roughly in the screenshot of 1 - you can use the ice features for 07-28 to compare the screenshot with the gif.

On watching the movie, it is seen that the ice in the movie region has definitely deteriorated over the 10 days. For example, identifiable larger floes seen close to the (180,80) point in the earlier frames appear to have broken up into non-identifiable smaller floes by the 27th and 28th, presumably with some melting and loss of ice surface area.
EDIT: no! On further inspection it appears that probably the largest floe in the movie started right next to the (180,80) point and ended up closer to the top RHS corner. That would be movement of a few tens of kilometers over 10 days, which is not unreasonable.

There is a lot of cloud cover. Perhaps the cloud obscured some of the changes in some regions, only revealing them in the last 3 days - giving the appearance of a more dramatic collapse.

A large part of the effect, at least in this region in the interior of the pack, appears to just be floes moving around, with gaps between adjacent floes opening or closing. With the floes not bound together, dispersion can create significant gaps without any actual melt.

So the change over the 10 day interval may have come from a combination of the above 3 effects.

Will the sun be shining on this region over the next few days and, if so, will it still be warm enough to put down some serious heat into the exposed liquid water and further melt the ice here?

[subgeometer]

a week in the pacific sector -with a higher res still of the most recent day(yesterday). That area will continue to cop a beating

[Frivolousz21]

Hell yeah solar can still wreck.

Above 400w/m2.

[oren]

Thanks to all today's posters for the images, animations and analysis. The pacific sector deep into the main basin appears so bad on all sources (and there are no clouds around to fool the satellites) so that there's no way it can survive a whole August of melting. It's a great example of the oft-repeated fact that ice can melt for a long while without much visible indication, and then over a few days goes poof when a critical thickness is reached and breached.
The big question remains whether the solidly concentrated CAB ice that seems to have been well protected from heat and movement will also reveal a vulnerability before the season is over. If it does, it's gonna be mighty interesting. If it remains solid, I guess we'll have to settle for a top-5 finish.

[Reallybigbunny]

WOW!!! What a ride. From a ho-hum beginning to the melt season to a really exciting conclusion, and, why does the melt season need to end... Volume is the key not extent. Been missing those regular PIOMAS posts.  I'm holding on to my armchair monitoring the Arctic sea ice. Much thanks to all who have posted.