IJIS

[gerontocrat]

Want to bet on that? 

In order to catch up with 2016, approximately 470,000 km2 of SIE must be lost by 9th July, which translates into roughly 95,000 km2 per day.

So, bet is on. That is all we can do now.

In order to confuse the issue, below is a little table showing the 2007-16 average daily melt 4th to 9th July. Damn close.

Below that is a graph I bashed up to try and get more of a grip on melting season progress. I am still thinking about what it shows. Definitely for 2012 the effect of the GAC in August, and perhaps to show that while the long-term average is smooth, an individual year is all over the place.

[Cid_Yama]

There seems to be a substantial number of people on here that, almost pathologically, ignore the difference in the condition of the ice, as well as the volume.  Yeah I know this thread is about extent.  But that doesn't mean you can just pretend all the rest doesn't exist.

Projections based on what happened in the past, focusing on extent exclusively, is beyond unrealistic.



 

[Shared Humanity]

Sorry to be a grump, but this whole horse race strikes me as a bit silly.  Arctic SIE is bumping bottom along with several other recent years within the error of the measurement system, no?

Yes and tracking it and comparing it to previous years is was this particular thread is about.

[Ned W]

There seems to be a substantial number of people on here that, almost pathologically, ignore the difference in the condition of the ice, as well as the volume.

I can't speak for anyone else here, but after more than a decade of "watching ice melt" I've pretty much given up on trying to infer "condition of the ice" as a meaningful predictor of September extent.  Every year people look at the satellite images and say "Wow, the ice sure looks terrible".  Then in some years the minimum ends up (relatively) higher and in other years lower.  Having gone through that cycle year after year I have learned to stop expecting that each year will be a new record low just because in some qualitative sense the ice "looks bad".

So that's why I focus so much on what's happened in the past.

If you can come up with a way of quantifying the "condition" of the ice that actually affects the results in September I'm all ears.

Volume/PIOMAS ... I'll comment on that later. Too many things happening right now.

[gerontocrat]

There seems to be a substantial number of people on here that, almost pathologically, ignore the difference in the condition of the ice, as well as the volume.  Yeah I know this thread is about extent.  But that doesn't mean you can just pretend all the rest doesn't exist.

Projections based on what happened in the past, focusing on extent exclusively, is beyond unrealistic.

Why do you assume that those who post on this thread "almost pathologically, ignore the difference in the condition of the ice, as well as the volume", and "pretend all the rest doesn't exist". The vast majority of ASIF members know that volume going down at 20% per decade but extent only at 13% is not sustainable. Sooner rather than later extent has to collapse. The question is - when?
The extraordinary weather over winter and spring and amazing loss in volume up to May made me think that perhaps this year is it. But climatic conditions in May and up to now plus the diminishing reduction in volume have made me think twice. I am convinced by Jim Pettit's postings in the PIOMAS thread that a new minimum volume is probable. I am unable to convince myself the same applies to extent. To achieve a record low, let alone the 1 million km2 minimum, requires melting conditions to be unique in the satellite record.

ps "Projections based on what happened in the past, focusing on extent exclusively, is beyond unrealistic." Once again, I wish to say that projections I have posted are not intended as forecasts in any sense of the word. They are tests of what has to happen for certain outcomes, e.g. a record low, compared with past melting seasons. That's all.

[Ned W]

The vast majority of ASIF members know that volume going down at 20% per decade but extent only at 13% is not sustainable. Sooner rather than later extent has to collapse.

To play Devil's Advocate for a moment ... why does that "have to" happen? 

Yes, they both ought to reach zero at the same time. But that could happen two ways:

* The rate of loss in extent could speed up to match volume
* The rate of loss in volume could slow down to match extent

I think there are lines of reasoning to support both of those. For now I am agnostic.

[Shared Humanity]

There seems to be a substantial number of people on here that, almost pathologically, ignore the difference in the condition of the ice, as well as the volume.

Not seeing it. Yes, we do have a few who regularly comment in ways that suggest they have denialist tendencies. Most of the regulars absolutely understand the complexities and those commenting here can be found on other threads talking about the woeful conditions of the ice.

[gerontocrat]

The vast majority of ASIF members know that volume going down at 20% per decade but extent only at 13% is not sustainable. Sooner rather than later extent has to collapse.

To play Devil's Advocate for a moment ... why does that "have to" happen? 

Yes, they both ought to reach zero at the same time. But that could happen two ways:

* The rate of loss in extent could speed up to match volume
* The rate of loss in volume could slow down to match extent

I think there are lines of reasoning to support both of those. For now I am agnostic.

Good point !! But both your possibilities demonstrate that the relationship is not sustainable.

AGW will continue for a good many years yet and therefore so will the Arctic continue to warm. With volume loss at about 75% and extent loss at around 50%, volume reduction would have to just about stop to equalize the two measures. (I feel a spreadsheet coming on and could not resist). So I put your second option firmly in the improbable (but not impossible) bracket.

An example of how to equalize volume and extent.
Reduce volume loss per annum by 75% to 0.5%, double extent loss rate to 2.5% per annum . Feasible ? - I don't think so. But here it is anyway.

[binntho]

There seems to be a substantial number of people on here that, almost pathologically, ignore the difference in the condition of the ice, as well as the volume.

I can't speak for anyone else here, but after more than a decade of "watching ice melt" I've pretty much given up on trying to infer "condition of the ice" as a meaningful predictor of September extent.  Every year people look at the satellite images and say "Wow, the ice sure looks terrible".  ...

I've only got a couple of years under my belt, and I've got the same feeling ... it seems that some people like to get all excited, which is absolutely fine, but there is no need to lambast those who don't.

[Cato]

Interesting the extremely low extension of ice in Hudson compared to the average. This could help flatten the curve in the next few days, considering also that synoptic configurations seem to be rather benign (to the ice) so far... Wait and see, as usual...

[Espen]

IJIS:

8,661,889 km²（July 4, 2017）down 80,041 km² and 3^rd lowest measured for the date.

[gregcharles]

Want to bet on that? 

In order to catch up with 2016, approximately 470,000 km2 of SIE must be lost by 9th July, which translates into roughly 95,000 km2 per day.

So, bet is on. That is all we can do now.

That I believe is possible. What I meant was do you want to bet that May 8 to July 3 isn't eight weeks. 

[Ned W]

I just posted the update from my JAXA predict-o-matic over in the July Poll thread.  Its initial prediction from June 10 has been pretty good so far, for such a naive model - observed extent loss is currently within 3.6% of predicted extent loss.

[Deeenngee]

What I find striking from Espen's extent chart is how there are six years that really close together at the moment, which then become quite widely spread out within 10 days or so. Perhaps we'll have a better idea around July 15th about 2017's trajectory, notwithstanding other metrics of course that most of us are probably watching. Or maybe not...

[magnamentis]

I'll place money on the certainty that 2017 will move below 2016 within the next eight weeks, and stay there for some time.

Ah well you would have lost ... just!

Not trying to be smart, but it does rather illustrate the folly of betting on the noise rather than the trend (sadly a much surer bet)

no matter whether it will be 9 weeks or a minor miss, what he really wanted to say is that conditions speak for an event on the negative side and it will eventually happen, no matter who says what.

thing is that the weather including temps and distribution of clouds and wind patterns cannot be predicted, neither that far out nor for a longer period of time. i will be tempted to get back to you
once we get there and last but not least.

considering the fact that we are permanently hovering around the minima, just different minima in different years while this year is almost permanently in the reach of any year's minimum for the time/day, i find the ongoing trials to say things are not as bad as they are a bit annoying, while some others, of course, how could it be otherwise, find my permanent sticking the finger into the wound annoying, LOL so be it, we shall all see and i'm sure that once things manifest themselves the tenor will, like so many times before, be unisono and everyone will speak like he had been on it all the time.

i think to quotes are necessary here to see the context

[Hyperion]

Well said magna. With the fragmented packs mobility its no surprize that extent has hung on a little. But with a large late snowmelt pulse and very large upswing in warm moist air influxes the recent plunge looks certain to accelerate. Its unfortunate that piomass seems to have departed to a parallel universe. The thickness charts are very much showing reality is much worse than either extent or the piomass model are admitting. Even stats on Area looks to be confounded by the fragmentation to levels below the size of analysis cells. But those that refuse to believe the ship is sinking and hide in their cabins until the water reaches their nostrils statistics say are 20-30% in studies of behaviours during shipwrecks. Shame these straws to cling to are being extended.

[oren]

Magna, everyone herevknows there is a chance, a risk, that this year will be a new record low extent. Some people give it low probabilty, with good reasons that they point out, others give it medium to high probabilty, with good reasons as well. You seem to give it 100% probabilty. Fine. But why constantly take offense when someone sees things differently? I fail to understand this.

Hyperion, what are the thickness charts you refer to? The only reliable ones I know of are PIOMAS and Cryosat. JAXA thickness is very unreliable AFAIK, if that's what you are refering to. And where do you find that PIOMAS has departed to a parallel universe? Why?

[greatdying2]

I must agree that extent is perhaps the worst metric one could conceive to measure the health of the ice. It will be the last one to crash and it will do so suddenly. If anyone is focussed primarily on extent, they are in for a mighty shock in not too many years (or perhaps weeks). While I do pay a little bit of attention to extent -- primarily because it is relatively easy and less error prone to measure / model than the all-important volume -- I do so with a sense of humour (dark humour).

[Feeltheburn]

I must agree that extent is perhaps the worst metric one could conceive to measure the health of the ice. It will be the last one to crash and it will do so suddenly. If anyone is focussed primarily on extent, they are in for a mighty shock in not too many years (or perhaps weeks). While I do pay a little bit of attention to extent -- primarily because it is relatively easy and less error prone to measure / model than the all-important volume -- I do so with a sense of humour (dark humour).

Worst metric, except it's the only one that can be readily observed rather than modeled. Love it or hate it, but until there is a different one that can be measured it's what we got. Not only that, it's the only metric going back to the early 1970s that can be used for comparison. No one knows really what the thickness and area were back then since they were not measured or modeled. DMI only models ice thickness back to 2003, so it's anyone's guess what it was in 1950, or even 1975 for instance. It's pretty well documented that 1979 was about the "iciest" in recorded history for arctic ice extent-it was likely lower before that but the data is sparse.

[Hyperion]

Well Oren. I guess the hycom gif posted by A-team
Re: The 2017 melting season
« Reply #2556 on: July 04, 2017, 06:03:03 PM »
Quote

The first animation simply flips back and forth between 10 July 2012 and 10 July 2017. As discussed earlier, the differences are not plausibly attributable to hycom thickness inaccuracy, model versioning or color palette transitions.

Really underlines it for me. I guess you can see a little extent sprawl in some of the peripheral areas probably due to the plasticity of the slush. But it does nit seem even close to what might bring same volume given the rest. I'M with jai when he says:

ummmm

PIOMAS says the June Avg differential between 2017 and 2012 is only about -750 km^3

This Hycom gridded data looks closer to several thousand km^3 LESS. . .

what gives?

[Espen]

IJIS:

8,572,935 km²（July 5, 2017）down 88,954 km² and 3^rd lowest measured for the date.

[Jim Pettit]

It's pretty well documented that 1979 was about the "iciest" in recorded history for arctic ice extent-it was likely lower before that but the data is sparse.

"Pretty well documented"? Huh? And why is it "likely lower" prior to 1979? The Hadley dataset (top graph) shows both that 1979 was nothing special, and that sea ice has been declining since at least the mid-1950s. An analysis of shipping records dating back to the 1700s show that there's less ice now then there has been in at least several hundred years. And the Kinnard paper (bottom graph) suggests there hasn't been so little ice in at least thousands of years.

(Of course, if you're talking about previous interglacial periods--say, 125,000 years ago, for instance--there was indeed much less ice, maybe even none. But that meltout was for far different reasons than we're seeing today.)

[Tor Bejnar]

It seems like 2017 has remained "3rd" for quite a while, even as other years 'bounce around' between 1,2,4,5 and 6.  As someone wrote recently, 'statistically, it has been a 6-way tie for a while.' 

And 2017 'wants' to be average 

[Pmt111500]

It's pretty well documented that 1979 was about the "iciest" in recorded history for arctic ice extent-it was likely lower before that but the data is sparse.

"Pretty well documented"? Huh? And why is it "likely lower" prior to 1979? The Hadley dataset (top graph) shows both that 1979 was nothing special, and that sea ice has been declining since at least the mid-1950s. An analysis of shipping records dating back to the 1700s show that there's less ice now then there has been in at least several hundred years. And the Kinnard paper (bottom graph) suggests there hasn't been so little ice in at least thousands of years.

(Of course, if you're talking about previous interglacial periods--say, 125,000 years ago, for instance--there was indeed much less ice, maybe even none. But that meltout was for far different reasons than we're seeing today.)

Hey, would the little ice age be the max as we come out of holocene maximum, or is there another period such as 14th century that would be the max ice point in the historical period? Maybe 6th century?

IJIS extent is still hanging way up, from what i expected but there's still plenty of time for the halocline to break properly.

[Jim Williams]

IJIS extent is still hanging way up, from what i expected but there's still plenty of time for the halocline to break properly.

Given recent trends (especially last winter), I'd say that the halocline has at least until late October.  I wouldn't put November out of consideration.

[Rubikscube]

@Hyperion. PIOMAS is the superior model when it comes to ice volume, so stop misleading people by pretending the accuracy of HYPCOM-thickness is even comparable. Why are you cluttering the IJIS thread with this nonsense in the first place? There are several threads dedicated to volume models. And please - this apply to multiple people - stop concern-trolling the legitimacy of the extent measurements every time extent drops fails to meet your expectations. IJIS has time and time again proven a great asset to us casual sea ice observers.

[Bill Fothergill]

It's pretty well documented that 1979 was about the "iciest" in recorded history for arctic ice extent-it was likely lower before that but the data is sparse.

"Pretty well documented"? Huh? And why is it "likely lower" prior to 1979? The Hadley dataset (top graph) shows both that 1979 was nothing special, and that sea ice has been declining since at least the mid-1950s. ...

@ Feeltheburn - As Jim P has already said, the meme that "It's pretty well documented that 1979 was about the "iciest" in recorded history for arctic ice extent" is, to say the least, highly questionable. (Except amongst those who regard the likes of Watts or Goddard as reliable sources.) It would be interesting if you could cite one, or more, of these "pretty well documented" sources.
(NB I am not in any way suggesting that you are a closet denier, merely that it would be interesting to learn how you came to that particular viewpoint.)

Here is an article on the NSIDC site which discusses pre-1979 data...
https://nsidc.org/cryosphere/icelights/2011/01/arctic-sea-ice-satellites

Here is a GRL article called "30-Year satellite record reveals contrasting Arctic and Antarctic decadal sea ice variability". As it was published in 2003, people can do the maths themselves.
https://nsidc.org/cryosphere/icelights/2011/01/arctic-sea-ice-satellites
{Oops, posted the same hyperlink twice by mistake!  }

http://onlinelibrary.wiley.com/doi/10.1029/2003GL018031/full


Part of the 1979 meme is the erroneous claim that microwave study of the Arctic only began in that year. I would suggest that it can be instructive to check out the Nimbus-5 mission, especially part of the scientific payload known as ESMR.

Additionally, there is an ongoing project to digitize the thousand of photos taken during various NASA missions from the early-60's onward. There is an article on this buried somewhere in - I think - the NSIDC Icelights pages.

[pauldry600]

A drop of around 60k in latest data.

I dont think a record is attainable

Theres about 65 days left and need around 80k a day to reach my own expected level of 3.7m

Thats reasonable I think

[Espen]

IJIS:

8,506,774 km²（July 6, 2017）down 66,161 km² and 3^rd lowest measured for the date.

[Tor Bejnar]

IJIS:

8,506,774 km²（July 6, 2017）down 66,161 km² and 3^rd lowest measured for the date.

The graph looks like 4th lowest to me.

[Hyperion]

@Hyperion. PIOMAS is the superior model when it comes to ice volume, so stop misleading people by pretending the accuracy of HYPCOM-thickness is even comparable. Why are you cluttering the IJIS thread with this nonsense in the first place? There are several threads dedicated to volume models. And please - this apply to multiple people - stop concern-trolling the legitimacy of the extent measurements every time extent drops fails to meet your expectations. IJIS has time and time again proven a great asset to us casual sea ice observers.

Point taken about the ot. But a question was asked so I answered it.
And no. Extent is doing exactly as I have been predicting and voicing reasons for the opinion. It is a far more mobile pack than we've seen before. And the extensive fragmentation and high salinity has been causing temps to be supressed as it melts in place instead of from tje edges. More hot steamhoses ate predicted. I would expect to see double or triple century drops regularly stsrting in  a few weeks.

[Peter Ellis]

Point taken about the ot. But a question was asked so I answered it.
And no. Extent is doing exactly as I have been predicting and voicing reasons for the opinion. It is a far more mobile pack than we've seen before. And the extensive fragmentation and high salinity has been causing temps to be supressed as it melts in place instead of from tje edges. More hot steamhoses ate predicted. I would expect to see double or triple century drops regularly stsrting in  a few weeks.

More than happy to bet you a hundred pounds that there won't be even a double century drop this year, let alone a triple.  Where do you get this stuff?

[greatdying2]

More than happy to bet you a hundred pounds that there won't be even a double century drop this year, let alone a triple.  Where do you get this stuff?

What odds are you offering?

[Neven]

According to my IJIS/JAXA spreadsheet covering 2005-now there has only been one double century break during July and August, on July 24th 2012: 229K.

There were near-double century breaks on July 12th 2011 (171K), July 1st 2013 (169K) and August 8th 2012 (183K).

I don't believe there has ever been a triple century break.

Don't take that bet, Hyperion. 

[magnamentis]

while such prediction come with a risk of a miss by a small fraction, i generally concur, especially to your explanation why things are as they currently are extent wise.

nevertheless we stay in touch with lowest levels despite of all that. without extremely ice-friendly weather which we can't foresee, it will be as you say, take or give a few.

the fact that there has never been a triple CB does not exclude the possibility for a first while of course it's a true fact "From The Past"

[Espen]

IJIS:

8,440,337 km²（July 7, 2017）down 66,437 km² and 4^th lowest measured for the date.

[Rubikscube]

Extent is doing exactly as I have been predicting and voicing reasons for the opinion. It is a far more mobile pack than we've seen before. And the extensive fragmentation and high salinity has been causing temps to be supressed as it melts in place instead of from tje edges. More hot steamhoses ate predicted. I would expect to see double or triple century drops regularly stsrting in  a few weeks.

Thats fair, I personally think the pack looks more fragmented on pictures from last year, but thats just my opinion, it - the pacific side - is certainly thinner than ever. Still don't think there will be double and triple century breaks though, considering that IJIS isn't prone to the same day to day fluctuations we see in CT and even Wipneus' numbers.

The odds? I'd give 2,2 for a double and 50 for a triple. No, I'm not taking any bets on that

[greatdying2]

Too bad there's no Intrade-like markets on this kind of thing -- could be fascinating. 

[Darvince]

The past two days have seen quite a slow loss rate for July...

[Hyperion]

I'll go 100 pounds of traditional pommie pork pies to 100 pounds of smoked New Zealand oysters on a double by the end of the month. 2:1 odds on the triple by the 15th of August. There's lots of steaming land vanquished of snow with plenty of hottest air of the year over the continents itching to use it. And as for ssts a little low on the Atlantic front. Floes have inertia. Every gust from the nth has been sloshing out the meltwater. Hiding the heat sliding in from the south underneath. And just wait until Veli s giant beavers shake the Siberian dirt from their fur and bob to the surface under the pole. The big late melt of the snow will make quite a hot blow.

[Neven]

I don't know about double and triple century breaks, but a series of (single) century breaks could be in the making given the current weather forecast.

[Espen]

IJIS:

8,386,935 km²（July 8, 2017）down 53,402 km² and 5^th lowest measured for the date.

[DoomInTheUK]

This is the Arctic we're talking about.
The only thing I'd bet on is that it won't do what you thought it would it the time frame you might expect in the area where you're looking.
It's a slippery little bugger.

[magnamentis]

This is the Arctic we're talking about.
The only thing I'd bet on is that it won't do what you thought it would it the time frame you might expect in the area where you're looking.
It's a slippery little bugger.

this is exactly what for the umpteenth time a had to admit to myself this morning, especially the time frame thingy, some of the events i expect to happen starting to be overdue and in another 10-15 days one has to seriously consider the possibility that they won't happen the way as expected at all

don't get me wrong, we're not there YET but the thoughts are starting to cross my mind

[pauldry600]

Bit of a slow down. Even getting to 3.7m could be perilously close now.

The thin ice that was a goner is gone n the less thin layer after that will melt slower until a lot of that gets thin and then it will be one or two century melts n then down to 50k again IMO

[Espen]

IJIS:

8,344,039 km²（July 9, 2017）down 42,896 km² and 5^th lowest measured for the date.

[DoomInTheUK]

Mag, I'll be expecting a major crash right up to the freezing season. Then it'll be an interesting freeze to watch. Being so damned unpredictable whilst at the same time knowing the direction of the trend is what makes Arctic watching so painfully addictive.

I'm sure a drug habit would be easier to handle!

[Cato]

As I expected, the decrease rate has slowed down due to an anticipated melting in the Hudson in the previous weeks. Fully agree with Neven that next few days will be conductive to melting especially on Beaufort and Chuckchi due to very warm air being sucked-in from the Pacific.

On the other hand, it seems to be a relatively quick event, as a huge LP with low gradient is going to settled down after about 72 hours, a condition relatively beneficial to the ice. Let's see what happens... I expect a few days of century declines followed by a new flattening of the curve.

[oren]

Kara, Baffin, Laptev and ESS "should" all go down sharply in the next few weeks.

[Ned W]

If I'm counting right, 2007, 2011, and 2013 each had century breaks in 6 of the next 7 days.  Wow. At the other extreme, 2010 had none, and 2008/2009/2014 only had 1 each.  Average daily losses range from 121K/day (2011) to 53K/day (2010).