Support the Arctic Sea Ice Forum and Blog

Author Topic: Arctic Summer Sea Ice transition  (Read 52898 times)

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #50 on: October 19, 2014, 04:02:34 PM »
Unfortunately, to me

In a nutshell, my argument is that «because it has in the past» isn't aggressive enough.

that sounds like nothing ever will be aggressive enough to you and this is naked environmental alarmism.

This seems to me to make attempts at debate and possibly even sharing understanding fairly pointless as nothing is good enough.

Taking a position that it doesn't matter what the evidence is, it isn't going to be aggressive enough seems to me to be very close to equivalent of saying the evidence should be ignored and the matter decided on principles of alarmist over-reaction. Thus anyone who takes such a position can easily be dismissed as having a position that is irrelevant to the argument.

If someone said 'some people have a genuine fear of spiders therefore we should treat spiders as mankind's worst enemy', would you ignore them?

Quote
(Frankly, it would be better if they gave us nothing.)
reads as if you preferred there was no climate science literature. This might give us more reason to decide on principles of alarmist environmentalism but it badly affects your credibility.
 

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #51 on: October 19, 2014, 04:31:43 PM »
Taking a position that it doesn't matter what the evidence is, it isn't going to be aggressive enough seems to me to be very close to equivalent of saying the evidence should be ignored and the matter decided on principles of alarmist over-reaction.
LOL, you truly are incredible. It seems TO YOU to be very close to equivalent of saying the evidence should be ignored and the matter decided on principles of alarmist over-reaction. And «taking a position that it doesn't matter what the evidence is, it isn't going to be aggressive enough» isn't what I am doing, but what you are thinking inside your organs for such activity that the fictional viddaloo might be thinking in a world where dismissing other views would be a lot easier for you.

Keep in mind that written sentences are also 'evidence'. Your way of reading my written sentences (that are provided for you right in front of you in a way that lets you read them as many times as you feel is necessary to grasp their meaning) tells me that «it doesn't matter to you what the evidence is, it isn't going to be anything but alarmist over-reaction anyhow», because that's your way of simplifying the world, by refusing to look at the evidence.
[]

TeaPotty

  • Frazil ice
  • Posts: 219
    • View Profile
  • Liked: 37
  • Likes Given: 71
Re: Arctic Summer Sea Ice transition
« Reply #52 on: October 20, 2014, 06:51:36 AM »
I tried following this thread, and I have yet to understand the hostility projected at Viddaloo.

It's like I mentioned in a previous thread, most mainstream scientists will better engage a climate denier in debate than "alarmists", and this thread is another great example. I think it so frustrates them that they cannot just prove to you that things can go equaly "both ways" (false equivalence), and not primarily negatively (as history and obs evidence show us). In this world, reality magically matches their ideals of moderation and objectivism. Unfortunately, this is like someone arguing with u about how *much* of your house will burn down if u just barely do anything to stop it - both frustrating and dangerous.

This also touches on the issue of hubris. No matter how many times the overly-conservative scientists are wrong, their is never a personal or public acknowledgement. They continue to retain credibility and shrug it off with a "life goes on" mentality. They are heroes in our current culture, here to tell everyone what they wanna hear, that we can shit where we eat and still have our champaigne. They are also those who best please the 1% and their cascade of money interests. Our best scientists are those who realize not only the full extent of their tools, but also their limits.
« Last Edit: October 20, 2014, 09:12:07 PM by TeaPotty »

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #53 on: October 20, 2014, 05:25:01 PM »
Well, as I said, less feelings, more numbers, that would be good.

When the Panel has been so wrong for so long, it's intriguing to see how well we can do with a simple trendline. We can also use math to determine how well the trendline approach has done in the past. That way it's not a matter of "values" whether the future is more severe than the simple trendline, but a matter of fact, numbers, math.

Huge proportions of humanity are deeply religious, and the last thing we need in climate science or in the climate debate is the borrowing of tools and methods from religious life. We'll see further with math.

In the case of the simple trendline for melt % at minimum (below), a simple control run shows that the trendline estimate for each new year 2000–2014 based on all previous years before that year, was too conservative in 9 out of 15 years.

Conclusion: The simple trendline will be too conservative, real–life more severe, 60% of the time.

qed.
« Last Edit: October 20, 2014, 06:56:11 PM by viddaloo »
[]

Laurent

  • Young ice
  • Posts: 2538
    • View Profile
  • Liked: 6
  • Likes Given: 35
Re: Arctic Summer Sea Ice transition
« Reply #54 on: October 20, 2014, 06:30:06 PM »
Some more links about news of the US military planning :
The Climate Post: U.S., Military to Plan More Strategically for Climate Change
http://www.huffingtonpost.com/tim-profeta/the-climate-post-us-milit_b_6015272.html?utm_hp_ref=green&ir=Green

ChrisReynolds

  • Nilas ice
  • Posts: 1714
    • View Profile
    • Dosbat
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #55 on: October 20, 2014, 09:02:36 PM »
Well, as I said, less feelings, more numbers, that would be good.

When the Panel has been so wrong for so long, it's intriguing to see how well we can do with a simple trendline. We can also use math to determine how well the trendline approach has done in the past. That way it's not a matter of "values" whether the future is more severe than the simple trendline, but a matter of fact, numbers, math.

Huge proportions of humanity are deeply religious, and the last thing we need in climate science or in the climate debate is the borrowing of tools and methods from religious life. We'll see further with math.

In the case of the simple trendline for melt % at minimum (below), a simple control run shows that the trendline estimate for each new year 2000–2014 based on all previous years before that year, was too conservative in 9 out of 15 years.

Conclusion: The simple trendline will be too conservative, real–life more severe, 60% of the time.

qed.



viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #56 on: October 28, 2014, 06:11:30 AM »
So 2014 starts out 6th in Yearly Average Extent and ends up 4th, yet for volume it starts up 3rd and ends up 5th. It moves two positions lower in extent and two positions higher in volume. The 'irritating' part of that is of course that I sense it may give some (unwanted) credit to Chris' slow–transition argument :)
[]

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #57 on: October 30, 2014, 07:51:12 PM »
All,

Please note:



compare:



These two graphs draw identical conclusions by utilizing different methods of analyzing the same data series.

What we have had now for about 4 (5?) years is a cultural bias within the Arctic Science community to rely on SIE data for their work.  Since this was the best data we have had for 30 years it is heavily favored.

Original opposition to the use of PIOMAS was (I believe) pretty strong, it was untested, theoretical, indefensible.  Only "fringe" researchers used it. 

Then some very capable (and clever) people over at MET were able to use Cryosat-2 data to verify it.  Sadly the top two researchers on the project died within 4 months of publishing their study due to tragic accidents.

However, their work stands, PIOMAS is verified.  The only reason we still use SIE is because of cultural inertia and bias.  (and magical thinking and intentional conservatism?)

In my understanding then, anyone who now relies on SIE as a predictive tool is not only doing themselves a disservice, they are doing science a disservice.  In failing to do going science, because of the gravity of the consequences, they are then doing a disservice to all of humanity.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #58 on: October 30, 2014, 08:22:16 PM »
I believe this was the last of Jai's graphs (above):

[]

oren

  • First-year ice
  • Posts: 6289
    • View Profile
  • Liked: 2309
  • Likes Given: 1940
Re: Arctic Summer Sea Ice transition
« Reply #59 on: October 31, 2014, 11:39:48 AM »
Putting in my two cents:
I have been convinced of the "slow transition" concept in that winter ice re-growth prevents an immediate finishing off of the ice. It's quite basic actually, even for a layman like me.
As to curve fitting, normally a very strong tool, I believe the curve we are watching mixes two different curves added together:
* The trend for the multi-year ice, the "savings bank" of the arctic, which is running out quickly.
* The trend for the first-year ice, the "annual income" of the arctic, which is coming back year after year due to winter-regrowth, slowly dropping away over the years.

You have a quickly-dropping line and a slowly-dropping line added together, and then you extrapolate the result. However, since each curve on its own cannot go below zero, you should extrapolate them separately and stop each extrapolation at zero, and then add the curves back together. This way it will be easy to understand why curve-fitting of the total curve (MYI + FYI) gives a wrong result, even if you accept trend-fitting as a valid forecast tool (I do).
If I knew how to show it graphically in this forum it might be easier to understand.

If you claim that the first-year ice curve has the same decline rate as the multi-year ice trend, then let's discuss that. (That's the physics issue).

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #60 on: October 31, 2014, 01:27:12 PM »
Nice explanation oren.

I would suggest there is still quite a lot of MYI so this fast dropping line could potentially continue for quite a while before the cannot go below zero stops it. Therefore I would suggest the split should be

MYI in excess of 2m
versus
FYI and MYI up to 2m

There is getting to be little MYI in excess of 2m so this line which was dropping fast is already having to begin to level off.

Sorry if this complicates your explanation, though I think it better explains why the levelling off ought to be imminent.

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #61 on: November 01, 2014, 02:07:51 AM »
Perhaps. Let's not hope so. The way I read the data from PIOMAS, it will be a decade tops from the first ice–free day till the first ice–free year.

[]

wili

  • Young ice
  • Posts: 3194
    • View Profile
  • Liked: 564
  • Likes Given: 385
Re: Arctic Summer Sea Ice transition
« Reply #62 on: November 01, 2014, 02:52:14 AM »
I'm not sure that graph shows what you think it shows, vid.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #63 on: November 01, 2014, 03:10:44 AM »
Oh, it shows what I think it shows, all right! Question is what YOU think it shows and what YOU think I think it shows. Unless you're willing to reveal some of this, then settling this sizzling uncertainty will be very, very difficult :p
[]

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #64 on: November 01, 2014, 01:30:37 PM »
Yearly average is an average - obviously a mix of high winter numbers and low late summer / autumn numbers.

When the low late summer numbers hit zero those cannot go any lower. This in itself is a reason for expecting the rate of decline to start to level off.

Winter regrowth is another reason to think the winter months trend will level off much more than the summer months trend.

So it is totally unrealistic to think this graph suggests 2020 for 1 day ice free*, 2030 for 6 months ice free and 2040 for year round ice free.

(2020 from https://sites.google.com/site/arctischepinguin/_/rsrc/1413370247922/home/piomas/grf/piomas-trnd6.png?height=360&width=480 )

It will take much longer than a decade to get from 1 day ice free to 6 months ice free. Then much longer again to be ice free year round.

oren

  • First-year ice
  • Posts: 6289
    • View Profile
  • Liked: 2309
  • Likes Given: 1940
Re: Arctic Summer Sea Ice transition
« Reply #65 on: November 01, 2014, 01:44:42 PM »
Perhaps. Let's not hope so. The way I read the data from PIOMAS, it will be a decade tops from the first ice–free day till the first ice–free year.



Viddaloo, since an ice-free year by definition implies an ice-free winter, let's forget physics for a minute and focus on curve-fitting. Please take a chart of the average winter volume, and do the curve-fitting to see when it might hit zero. I am highly interested in the result. (Would do it myself, but lack the data and the know-how).

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #66 on: November 01, 2014, 06:35:59 PM »

It will take much longer than a decade to get from 1 day ice free to 6 months ice free. Then much longer again to be ice free year round.

hmmm, wouldn't this depend on regional forcing?  Under which RCP scenario do you expect this result?

What if aerosols are grossly underestimated, aerosol production resumes an upward trend in the northern hemisphere and then, suddenly, stops?  This would result in an immediate (2-week) jump in the climate forcing mechanisms, potentially by 25%.


Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #67 on: November 01, 2014, 06:46:00 PM »

Viddaloo, since an ice-free year by definition implies an ice-free winter, let's forget physics for a minute and focus on curve-fitting. Please take a chart of the average winter volume, and do the curve-fitting to see when it might hit zero. I am highly interested in the result. (Would do it myself, but lack the data and the know-how).




Wipneus' maximum volume graph shows an ice free winter around 2050-2085 (eyeball estimate)



(thanks crandles, yes, that is the one)

some here (chris Reynolds) believe that the models that show an increased persistence with summer ice melt are correct and the long-range projection is much more likely.  Others (myself at least!) believe that the models fail to include regional enthalpy gains adequately and that a tipping point will occur, causing  a much more rapid arctic ice decline in summer and an accelerated Winter decline. 

My estimates of year around ice free states follow along the Wipneus projections I stated above (2050-2085)  I don't know what Chris thinks exactly  but I would guess that it is a bit longer than this.
« Last Edit: November 02, 2014, 12:01:59 AM by jai mitchell »
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #68 on: November 01, 2014, 08:10:46 PM »

It will take much longer than a decade to get from 1 day ice free to 6 months ice free. Then much longer again to be ice free year round.

hmmm, wouldn't this depend on regional forcing?  Under which RCP scenario do you expect this result?

What if aerosols are grossly underestimated, aerosol production resumes an upward trend in the northern hemisphere and then, suddenly, stops?  This would result in an immediate (2-week) jump in the climate forcing mechanisms, potentially by 25%.

Yes, if you change the scenario, then you should expect the results to change though I am not sure we are likely to see much difference in the next 20 or 30 years from CO2 emissions between scenarios and by the time we get out to 30 years there is a large range of possible situations. Yes aerosol forcing can have more effect on a shorter timescale.

It was a curve extrapolation, which I think should be taken to be as a 'if things continue as they are going' sort of BAU scenario.

I neglected this on basis that it was implicitly implied by such a graph - I should probably be more careful about what I say potentially being taken out of context. The shape of the fitted curve that Viddaloo used and the conclusions he seemed to be drawing seem a little more important to me.

Guess the wipneus graph you wanted was this updated one

otherwise winter ice free looks much sooner than 2050-2085

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #69 on: November 01, 2014, 09:05:16 PM »
So it is totally unrealistic to think this graph suggests 2020 for 1 day ice free*, 2030 for 6 months ice free and 2040 for year round ice free.
Luckily, then, no–one in the known universe has suggested that, apart from yourself.

If I were more interested in people than I am in sea ice, I might study and try and find out where those voices in people's heads come from that tell them «ohno, he doesn't say what he says and which is just in front of me, in writing, he must be saying something else, and this something else that I think he might be saying is really stupid, so I'll make a post where I tell everyone how silly that is».

But I'm certainly not THAT interested in people. And I'm not at all religious, so I don't think Satan plays a role on this board. Although some of the more excessively creative «misreadings» might suggest otherwise.  ;D
[]

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #70 on: November 01, 2014, 09:26:39 PM »
Perhaps. Let's not hope so. The way I read the data from PIOMAS, it will be a decade tops from the first ice–free day till the first ice–free year.



Viddaloo, since an ice-free year by definition implies an ice-free winter, let's forget physics for a minute and focus on curve-fitting. Please take a chart of the average winter volume, and do the curve-fitting to see when it might hit zero. I am highly interested in the result. (Would do it myself, but lack the data and the know-how).

Oren, I think Chris Reynold's already done that and found Winter will crash in the 30s.

Just found this. Chris writes in April:

Quote
If all of this seems ridiculous to you, then consider the alternative to an inflection in the trend of April volume in the Central region, continuing the trend regardless gives an ice free Arctic in April by 2037, surely nobody expects that!

I also think Jai's eyeballing of Wipneus' April graph is errant, it is outside of the chart, but it's certainly steep enough to crash in the 2030s.
« Last Edit: November 01, 2014, 10:10:15 PM by viddaloo »
[]

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #71 on: November 01, 2014, 10:02:37 PM »
Please take a chart of the average winter volume, and do the curve-fitting to see when it might hit zero. I am highly interested in the result. (Would do it myself, but lack the data and the know-how).

As today's November 1st, what better day for the launch of a practical Winter definition of November—April.
[]

oren

  • First-year ice
  • Posts: 6289
    • View Profile
  • Liked: 2309
  • Likes Given: 1940
Re: Arctic Summer Sea Ice transition
« Reply #72 on: November 01, 2014, 11:02:43 PM »
So Viddaloo, curve-fitting the annual volume gives a zero at 2030, but curve-fitting the 6-month winter volume gives a zero around 2035. Can you do the same curve-fitting for the Feb-Apr average (top ice months)? I have a feeling that it will give an even later timeframe for zero ice.

Since the average annual trend volume cannot be zero as long as winter volume has still not crashed to zero, 2030 is a wrong curve-fitting calculation. (In effect it averages positive winter volume with negative summer volume)
Bottom line - curve-fitting a trend that is a combined sum of several trends with different slopes gives a wrong result when each trend on its own cannot go below zero.

(Note I am not discussing Chris's convincing claim that the winter volume trend should slow down its slide in the coming years. I am focusing on curve-fitting the existing trends using your own methods)

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #73 on: November 01, 2014, 11:22:22 PM »
Actually, it is your method. You wanted to make a Winter volume graph, if you had the skills and data to do it. You didn't, so you asked me to do it for you.

Your logic: As Winter crash estimates give a slightly (3 years) later year than Annual crash estimates, the latter must be wrong. Assuming, of course, that the Winter crash estimate is *correct*.

This is your assumption, so let's go with that. All Arctic sea ice will be gone by 2034. Now, that's still a couple decades before the holy IPCC says we'll sea the very first *day* of no ice.

Why do you think that is, oren?
[]

oren

  • First-year ice
  • Posts: 6289
    • View Profile
  • Liked: 2309
  • Likes Given: 1940
Re: Arctic Summer Sea Ice transition
« Reply #74 on: November 01, 2014, 11:32:01 PM »
I was merely pointing out a miscalculation when using curve-fitting. Doesn't have anything to do with the IPCC (though I do believe the IPCC is very wrong)

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #75 on: November 01, 2014, 11:48:20 PM »
I was merely pointing out a miscalculation when using curve-fitting. Doesn't have anything to do with the IPCC (though I do believe the IPCC is very wrong)

So you're not using your peculiar logic to defend IPCC estimates? Good.

I assume you know what you're doing when you want to throw away first *half* the data, and then ¾ of the data. You're then expecting estimates to be better (more correct) the more data you forget about.

The reason I use Yearly Average volume instead of, say, Yearly Minimum volume, is that the latter represents one day only. The former represents 365 days. The ocean that causes the ice–melt phenomenon that we're all studying is a 365/24/7 type operation, with no sickdays or holidays.
[]

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #76 on: November 02, 2014, 12:08:45 AM »
only when the maximum day goes to zero will you have a 365/7/24 full year of ice free.

to me, looking at winter ice volumes is off base.  Albedo feedbacks are the primary concern.  The only reason winter ice volumes matter is how they impact regional temperatures during the melt phase, when and how strong.  The only thing that matters to me is regional insolation absorption by land and sea and the resulting enthalpy increases accumulating through late September when ESAS and regional permafrost degradation result in significantly increased natural sources of carbon (and significantly weaker oceanic carbon sinks).

When we get to a place where winter ice is significantly lower than the current average volume, when this lends itself to an earlier and earlier ice-free summer arctic.  Then the albedo feedback in the arctic will result in as much warming, on the global average as 2XCO2.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

oren

  • First-year ice
  • Posts: 6289
    • View Profile
  • Liked: 2309
  • Likes Given: 1940
Re: Arctic Summer Sea Ice transition
« Reply #77 on: November 02, 2014, 12:09:42 AM »
This is my last comment on the subject of curve-fitting of averages:
I am not forgetting any part of the data. I'm just separating it to components when they behave differently from each other.

Mathematically, summer ice gone by 2020 (based on summer curve) and Feb-Apr ice gone by 2040 (or whatever the Feb-Apr trend gives us), does NOT equal to all annual ice gone by 2030 (as shown by the annual average trend). You simply cannot average such data where each component separately cannot go below zero, and still expect curve-fitting to be correct.

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #78 on: November 02, 2014, 12:18:58 AM »
Mathematically, summer ice gone by 2020 (based on summer curve) and Feb-Apr ice gone by 2040 (or whatever the Feb-Apr trend gives us), does NOT equal to all annual ice gone by 2030 (as shown by the annual average trend). You simply cannot average such data where each component separately cannot go below zero, and still expect curve-fitting to be correct.

Well, you can, and should, IMO. The September crash graph is errant because it's based on one day (or month) only, forgetting about the rest of the year. The Feb–Apr crash graph is errant because it's based on 3 months only, forgetting about the rest of the year. We have no Feb–Apr planet, only an all–year one.

When using the entire year as your basis you do not make this type of error. Therefore the annual meltdown estimate has a higher probability of being correct than the shorter period estimates.

So in a nutshell: The most reliable method for prediction of an April full meltdown is to use data for the whole year, not just April average (one month) or April maximum (one day).
[]

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #79 on: November 02, 2014, 01:34:58 AM »
Quote
So in a nutshell: The most reliable method for prediction of an April full meltdown is to use data for the whole year, not just April average (one month) or April maximum (one day).

This is not a true statement. 

you are not thinking clearly on this.  You need to weight the monthly terms by how much they each affect the April minimum.  (hint: april's value is higher)

consider:  when September is first zero and then 10 years later, how much more has the new zero impacted the annual average than the first one?
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #80 on: November 02, 2014, 02:22:55 AM »
When the low late summer numbers hit zero those cannot go any lower. This in itself is a reason for expecting the rate of decline to start to level off.

This in my view is an understanding of the system that forgets about the physics, ie the ocean enthalpy. In a way you are saying that as ocean heats to the point of ice–melt, it cannot heat further. We all know that to be wrong. Water can easily heat to 100 C before it starts boiling and turns into gas (vapor).

In an Arctic context there is a continuum: Ocean continues to heat, it gets to keep that heat into the next day, and thus everything continues, it doesn't drop dead the day Summer ice melts.

You are, in other words, confused by the number zero. This implies you are looking exclusively at the ice, and not at the ocean melting it. If you look instead at the warming ocean, there is no number zero and no brick–wall to crash into. Instead steady warming continues.

Quote from: Monty Python
A year passed. Winter changed into Spring. Spring changed into Summer. Summer changed back into Winter. And Winter gave Spring and Summer a miss and went straight on into Autumn. Until one day...

The extra albedo effects of earlier and longer–lasting meltdowns will, together with energy saved (no more work needed to melt ice during that period) ensure a very aggressive expansion of the meltdown period in both directions. And that is without considering all the other strong positive feedbacks (melting onshore and offshore permafrost, snow–cover albedo, darkening from Boreal wildfires, fierce cyclones etc).

In a One Decade scenario (first open day to first open year) the open sea period will on average increase by 1.2 months per year. That gives this hypothetical timetable for the final melt:

2021: 1 day meltdown.
2022: 1.2 months meltdown.
2023: 2.4 months meltdown.
2024: 3.6 months meltdown.
2025: 4.8 months meltdown.
2026: 6 months meltdown.
2027: 7.2 months meltdown.
2028: 8.4 months meltdown.
2029: 9.6 months meltdown.
2030: 10.8 months meltdown.
2031: 12 months meltdown.

NB! With positive feedbacks and abrupt events added, things will probably move a lot faster, though.
[]

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #81 on: November 02, 2014, 02:35:38 AM »
When the low late summer numbers hit zero those cannot go any lower. This in itself is a reason for expecting the rate of decline to start to level off.

This in my view is an understanding of the system that forgets about the physics, ie the ocean enthalpy. In a way you are saying that as ocean heats to the point of ice–melt, it cannot heat further. We all know that to be wrong. Water can easily heat to 100 C before it starts boiling and turns into gas (vapor).

In an Arctic context there is a continuum: Ocean continues to heat, it gets to keep that heat into the next day, and thus everything continues, it doesn't drop dead the day Summer ice melts.

You are, in other words, confused by the number zero. This implies you are looking exclusively at the ice, and not at the ocean melting it. If you look instead at the warming ocean, there is no number zero and no brick–wall to crash into. Instead steady warming continues.

Quote from: Monty Python
A year passed. Winter changed into Spring. Spring changed into Summer. Summer changed back into Winter. And Winter gave Spring and Summer a miss and went straight on into Autumn. Until one day...

The extra albedo effects of earlier and longer–lasting meltdowns will, together with energy saved (no more work needed to melt ice during that period) ensure a very aggressive expansion of the meltdown period in both directions. And that is without considering all the other strong positive feedbacks (melting onshore and offshore permafrost, snow–cover albedo, darkening from Boreal wildfires, fierce cyclones etc).

In a One Decade scenario (first open day to first open year) the open sea period will on average increase by 1.2 months per year. That gives this hypothetical timetable for the final melt:

2021: 1 day meltdown.
2022: 1.2 months meltdown.
2023: 2.4 months meltdown.
2024: 3.6 months meltdown.
2025: 4.8 months meltdown.
2026: 6 months meltdown.
2027: 7.2 months meltdown.
2028: 8.4 months meltdown.
2029: 9.6 months meltdown.
2030: 10.8 months meltdown.
2031: 12 months meltdown.

NB! With positive feedbacks and abrupt events added, things will probably move a lot faster, though.

This is all very good, excellent I think.  However, none of this is implied by using current annual average declines as a predictive tool.  It is simply you asserting a series of tipping points and justifying non-linear behavior that is apart from the physics that is currently driving sea ice volumes down.  (well partially, I think that most of those feedbacks you listed have varying degree on current ice regimes).  You didn't include a massive methane release or catastrophic decline in anthropogenic aerosol emissions, both of which, I feel may have identical probabilities (as one may very well induce the other).
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #82 on: November 02, 2014, 02:54:33 AM »
you are not thinking clearly on this.  You need to weight the monthly terms by how much they each affect the April minimum.  (hint: april's value is higher)

I believe I am, Jai. April is a special case, and zero ice is a special case. Zero ice in April naturally coincides with a Yearly Average Volume of zero km³.

This works both ways in this special case: The year you have a Yearly Average Volume of zero km³, you will also have zero ice in April.

Quote
consider:  when September is first zero and then 10 years later, how much more has the new zero impacted the annual average than the first one?

Interesting question, and I get what you're saying, but I fear you fall into the same trap as oren when he's «separating it to components», which is where he makes a mistake, IMO. In your case you're thinking the daily volume of zero cannot go lower than zero, so YAV decline will flatten. What you should be thinking is how many other daily zeros you will have before and after this first daily zero, the next year and the following years. This increased amount of zeros will certainly bring the YAV down.

So the graph works. The same September day 10 years later will not be lower than zero, but it will deliver increasingly warmer ocean water to the following days. And as the zero ice period expands rapidly into August, July and June, with much higher insolation, this effect will be considerable.
[]

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #83 on: November 02, 2014, 03:44:24 AM »
I see a synthesis between Viddaloo and Chris Reynolds.

Viddaloo is right that the accumulation of enthalpy and other tipping point factors will continue to exacerbate annual sea ice losses after the first ice-free September.  Chris is also right that the rate of heat energy lost to the atmosphere and space in the arctic winter will increase exponentially as ice reforms after the first ice-free September.

These two basic premises are what has led me to conclude that we will see a Gompertz curve fit to arctic ice declines.  There will certainly be a rapid increase in autumnal temperatures but not enough to preclude sea ice formation in the dark boreal winter!  Not for several more decades. 

However, there are certain tipping points that these events will bring about that will lead to an ice free state as the arctic cell collapses and subtropical and even tropical moisture invades the polar region. 

For instance, when the June 1st ice melt occurs, the arctic ocean warming will basically halt the Atlantic Meridional Overturning Circulation.  This will lead to rapidly cooling sea surface temperatures in the north atlantic but the mid atlantic will begin to warm, causing massive hydrological changes, pushing the moisture envelope further northward. 

So Viddaloo says (about) 2039  I say (about) 2065 and Chris says beyond 2100 for a year-around ice free arctic. 

too bad modern civilization won't be able to coexist with an RCP 8.5 emission pathway or we could start an annuity and make a bet for the winner's grandchildren to receive.    So, in any event BAU emissions cannot possibly occur past 2050 even if we tried.  (and economics is actually pushing the renewable envelope faster than previously projected).  So we won't see BAU in even 2020.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Michael Hauber

  • Grease ice
  • Posts: 900
    • View Profile
  • Liked: 77
  • Likes Given: 14
Re: Arctic Summer Sea Ice transition
« Reply #84 on: November 02, 2014, 08:52:04 AM »
Until we know why melt has been faster than IPCC model predictions then we don't know whether it is because of some feedback factor that the typical models are not including, or whether some natural variation is causing the faster than expected melt.

I believe it is reasonable that global warming will resume in the future to match what IPCC models predict despite the fact that warming has recently been slower than predicted.  I believe it is reasonable (but not certain) that the arctic ice cover will 'recover' to follow the IPCC model predictions even though recent melt has been faster than predicted.  The gap between model and predictions does seem more extreme on arctic ice than global temperatures.  However I'd expect natural variations which can move heat from one part of the planet to the other to have a more extreme impact on a regional area than on the globe as a whole.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #85 on: November 02, 2014, 07:57:07 PM »
Michael,

it is fine to have "opinions" but if you don't state WHY you believe what you believe then you are simply trolling.

so, for the sake of integrity in the thread, what is the reason for your opinion that the arctic sea ice will "recover" and that global atmospheric temperature increase will "resume"? (by the way you realize that we are poised to overtake 1998 el nino this year without an el nino in the pacific right?)

So, what mechanism do you suggest is causing the increase in ice loss over the last 25 years and what mechanism will restore ice levels to within the IPCC prediction range?
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #86 on: November 02, 2014, 08:40:58 PM »
Here are April and September average months plotted with best fit 4 parameter gompertz fits.

PIOMASVolumemax min4parameterGompertz by crandles2011, on Flickr

Formulae
=9.378*exp(-exp((0.123*($A10-2005.14))))+22.2837
=10.235*exp(-exp((0.1587*($A10-2005.04))))+5.007

by definition of the shape of curve, the lines will go horizontal but the method is free to choose what height they are at to best fit the data.

Just to be clear I do not believe the volume will go horizontal as shown - I believe it will continue downwards.

Clearly you can have the projection going off in any sensible direction and still have a smooth curve through the data. So it is the choice of curve type that decides which way an extrapolation goes not the data.

Not really sure if the heights this method selects to level out at are interesting or not really. The minimum has probably had a high year and this will bias the height at which the curve levels out on the high side.

Also of possible interest, the method thinks the point of inflection was 2005.14 for the maximum and 2005.04 for the minimum. Surprisingly similar? Is the same date for an inflection what we should expect to see? I would suggest yes but whether these dates being close is something worth noting or not I am much less sure.

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #87 on: November 03, 2014, 01:09:49 AM »
Here are April and September average months plotted with best fit 4 parameter gompertz fits.


OK. So basically you're saying everything's OK from now on, starting tomorrow? Or is it January 1st? Please explain the physical (or perhaps spiritual) basis for thinking that.
[]

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #88 on: November 03, 2014, 01:19:51 AM »

OK. So basically you're saying everything's OK from now on, starting tomorrow? Or is it January 1st? Please explain the physical (or perhaps spiritual) basis for thinking that.

what part of

Quote
Just to be clear I do not believe the volume will go horizontal as shown - I believe it will continue downwards.

Clearly you can have the projection going off in any sensible direction and still have a smooth curve through the data. So it is the choice of curve type that decides which way an extrapolation goes not the data.

didn't you understand?

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #89 on: November 03, 2014, 01:31:40 AM »
If the nature of the data was that the curve getting ever steeper was best fit then that is what the best fit 4 parameter gompertz fit would show. But it doesn't; the best fit shows the curve getting less steep from 2005.

Please note that I do accept that this is very very weak evidence and subsequent years data could easily reverse this finding.


Apocalypse4Real

  • Frazil ice
  • Posts: 370
    • View Profile
  • Liked: 5
  • Likes Given: 1
Re: Arctic Summer Sea Ice transition
« Reply #90 on: November 03, 2014, 05:29:47 AM »
For what its worth, Peter Wadhams gave a presentation today, making his case for a an ice free month in 2020.

An excerpt follows:

"No models here," Peter Wadhams, professor of applied mathematics and theoretical physics at the University of Cambridge in England, told the Arctic Circle Assembly on Sunday. "This is data."

Wadhams has access to data not only on the extent of ice covering the Arctic, but on the thickness of that ice. The latter comes from submarines that have been beneath the ice collecting measurements every year since 1979.

This data shows ice volume "is accelerating downward," Wadhams said. "There doesn't seem to be anything to stop it from going down to zero.

"By 2020, one would expect the summer sea ice to disappear. By summer, we mean September. ... (but) not many years after, the neighboring months would also become ice-free."

See: http://www.adn.com/article/20141102/expert-predicts-ice-free-arctic-2020-un-releases-climate-report

Michael Hauber

  • Grease ice
  • Posts: 900
    • View Profile
  • Liked: 77
  • Likes Given: 14
Re: Arctic Summer Sea Ice transition
« Reply #91 on: November 03, 2014, 10:24:31 AM »
Michael,

it is fine to have "opinions" but if you don't state WHY you believe what you believe then you are simply trolling.

so, for the sake of integrity in the thread, what is the reason for your opinion that the arctic sea ice will "recover" and that global atmospheric temperature increase will "resume"? (by the way you realize that we are poised to overtake 1998 el nino this year without an el nino in the pacific right?)

So, what mechanism do you suggest is causing the increase in ice loss over the last 25 years and what mechanism will restore ice levels to within the IPCC prediction range?

I said may, not will.

And I said we don't know what the mechanism, and because we don't know what the mechanism is, we don't know whether it will continue or stop.  Maybe its AMO.  Maybe IPCC missed a feedback.  If its AMO arctic melt will return to as far above IPCC predictions as it was below when the AMO switches phase.  If its a missed feedback it won't.  Or it could be some of both, or other stuff I'm not smart enough to think of.

Do you know what mechanism caused the sea ice to melt faster than predicted?  Is there another way of knowing that the faster than predicted ice melt is guaranteed to continue?

And yes I realise we are in with a good chance of beating 1998's el nino temperature in a neutral year.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #92 on: November 03, 2014, 06:35:29 PM »
Mike,

Well, I expect that AMO will not return to a negative phase, ever.  (or at least, not unless massive anthropogenic or volcanic aerosols (or other geoengineering activities i.e. space mirrors. . . occurs) Since AMO is based on SST trends.

and SST trends are doing this



My understanding is that there are several factors driving sea ice declines.

1. increased positive forcing due to GHG emissions
2. increased injection of warming mid-latitude surface waters into the arctic via eddy currents (Maslowski models)
3. regional spring warming due to land-ocean effects, including but not limited to first-order feedbacks from negative Eurasian snow-cover anomalies


My understanding of the "recovery" potential (i.e. slowing or even temporary reversal of ice loss trends) are:

1.  increased anthropogenic aerosol abundances and/or covert geoengineering activities by private or government actors.  (this second cannot be ruled out).
2.  changes in mid-latitude heat and moisture transport regimes into arctic due to weakening jet stream resulting in cloudier arctic springs, lower spring temperatures and fewer melt-ponds.


Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #93 on: November 03, 2014, 09:54:10 PM »

OK. So basically you're saying everything's OK from now on, starting tomorrow? Or is it January 1st? Please explain the physical (or perhaps spiritual) basis for thinking that.

what part of

Quote
Just to be clear I do not believe the volume will go horizontal as shown - I believe it will continue downwards.

Clearly you can have the projection going off in any sensible direction and still have a smooth curve through the data. So it is the choice of curve type that decides which way an extrapolation goes not the data.

didn't you understand?

Guess I'm just struggling to see the motivation for posting a graph not even you believe in. If your point is graphs can be misleading, then OK, you proved it. Well done. Chris made one of those, too, where he assumed 2014 would get hotter and melt more and more ice even past Solstice and all through August. That was wrong, too. Graphs can be wrong.

[]

Michael Hauber

  • Grease ice
  • Posts: 900
    • View Profile
  • Liked: 77
  • Likes Given: 14
Re: Arctic Summer Sea Ice transition
« Reply #94 on: November 03, 2014, 10:32:51 PM »
Mike,

Well, I expect that AMO will not return to a negative phase, ever.  (or at least, not unless massive anthropogenic or volcanic aerosols (or other geoengineering activities i.e. space mirrors. . . occurs) Since AMO is based on SST trends.

and SST trends are doing this



My understanding is that there are several factors driving sea ice declines.

1. increased positive forcing due to GHG emissions
2. increased injection of warming mid-latitude surface waters into the arctic via eddy currents (Maslowski models)
3. regional spring warming due to land-ocean effects, including but not limited to first-order feedbacks from negative Eurasian snow-cover anomalies


My understanding of the "recovery" potential (i.e. slowing or even temporary reversal of ice loss trends) are:

1.  increased anthropogenic aerosol abundances and/or covert geoengineering activities by private or government actors.  (this second cannot be ruled out).
2.  changes in mid-latitude heat and moisture transport regimes into arctic due to weakening jet stream resulting in cloudier arctic springs, lower spring temperatures and fewer melt-ponds.

The AMO index will  tend to stay positive as long as global warming is faster than the long term trend, and go negative when it becomes slower than the long term trend (as we approach whatever equilibrium we end up at/near).  That does not mean there is not something that we could call the AMO which is alternating between causing the Atlantic to be warmer and cooler than it otherwise would be. 

Your three factors affecting Arctic ice would be an explanation for why ice has been melting faster than IPCC expected, and an indication that this faster than predicted melt can be expected to continue if either IPCC has not included these factors (seems unlikely), or if they have included these factors but underestimated them.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Steven

  • Grease ice
  • Posts: 633
    • View Profile
  • Liked: 198
  • Likes Given: 17
Re: Arctic Summer Sea Ice transition
« Reply #95 on: November 03, 2014, 11:18:32 PM »
I expect that AMO will not return to a negative phase, ever.  (or at least, not unless massive anthropogenic or volcanic aerosols (or other geoengineering activities i.e. space mirrors. . . occurs) Since AMO is based on SST trends.

There seems to be a discussion among climate scientists about how the AMO should be exactly defined.  A 2014 paper by Mann et al. (pdf) suggest that the "true" AMO signal has been in a cooling phase in the last few decades.  See also the Penn State news release for the Mann et al. paper:

http://news.psu.edu/story/310769/2014/04/07/research/slowdown-global-warming-fleeting

Quote
"Some researchers have in the past attributed a portion of Northern Hemispheric warming to a warm phase of the AMO," said Michael E. Mann, Distinguished Professor of Meteorology. "The true AMO signal, instead, appears likely to have been in a cooling phase in recent decades, offsetting some of the anthropogenic warming temporarily."

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #96 on: November 04, 2014, 12:19:32 AM »

Guess I'm just struggling to see the motivation for posting a graph not even you believe in. If your point is graphs can be misleading, then OK, you proved it. Well done. Chris made one of those, too, where he assumed 2014 would get hotter and melt more and more ice even past Solstice and all through August. That was wrong, too. Graphs can be wrong.

Do I have to spell it out even more clearly?

Firstly I wanted to show that you can have a smooth curve through the data with the extrapolation going off in a weird direction.

I wanted the direction to be sufficiently weird that you would realise that you could have other curves that go off in all the sensible directions.

Having envisaged multiple curves with different extrapolations, which one is correct? Simple answer we just don't know and most must be wrong.

You wrote in your signature link
"The beauty of a fact-based scatter plot with a simple trendline is that it's theory free. The graph simply tells you this is what we've got. "

Now consider what you have done. You started with choosing a curve that got ever steeper then went looking for the best fit of that type. This fit through the data has an ever steepening curve - gosh what a surprise NOT.

Instead if you choose a curve type that allows the fit to get ever steeper over the data or it can get steeper and then shallower again and go off to find the best fit with that type of curve. If you then get a curve that gets ever steeper you know that is what the data is telling you. Likewise, as is the case here, if the fit has the curve getting steeper then less steep again then we know there is a hint of that in the data.

By allowing the curves to do different things you really get to find out 'what we've got'. In comparison, by specifying one curve type you were specifying what you were going to find in advance. 'Seek and ye shall find something to back up what you wanted to find' is a truism and is not very good evidence.

I have been clear that this hint of a slowing rate of decline isn't very strong. i.e. I am criticising my own method and thoughts. I haven't seen much evidence of you doing that.

crandles

  • Young ice
  • Posts: 2749
    • View Profile
  • Liked: 163
  • Likes Given: 55
Re: Arctic Summer Sea Ice transition
« Reply #97 on: November 04, 2014, 12:41:20 AM »
PIOMASVolumemax&minExtrapolatebelievable by crandles2011, on Flickr

My expectation is more like light blue and purple lines for April and September average volumes.

Why?

The gap between those lines gets wider at a rate of 20% because this is what I found they had been doing recently. The September average hits zero when the April average is down to about 18700km^3.

There is a wide range of slopes that may be possible with little to choose between them.



I calculated averages for each band. If I dump all the thickness over 2.5 meters the rate of thinning is reduced to about 70% of the rate for 1991 to 2011. The April extrapolation has about 70% of the slope between 1991 to 2011. I am not very confident about this slope being anywhere near correct.

FWIW, the purple line hits zero at 2032 though obviously with the noise about the trend it could happen by occasionally starting about 2025. The September curve only reaches zero by 2111 but that might be too early as there is loads of time for the line could curve towards later dates.

jai mitchell

  • Nilas ice
  • Posts: 2078
    • View Profile
  • Liked: 116
  • Likes Given: 24
Re: Arctic Summer Sea Ice transition
« Reply #98 on: November 04, 2014, 04:01:25 AM »
Crandles,

in your new best fit curve for PIOMAS volume, what if 20,000 KM^3 is a winter tipping point where by winter ice formation becomes radically slower, resulting in earlier and earlier summer ice free states.  This is more akin to the tipping point effects that both Vid and I see as resulting from large scale systemic enthalpy increases.

What if, as September becomes ice free and winter volumes become sufficiently thin that a rapid winter decline occurs due to compounding summer enthalpy effects, say around 2025, where would your winter curve go then (assuming summer stays the same (I think it will plateau a bit at the end).
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

viddaloo

  • Nilas ice
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Arctic Summer Sea Ice transition
« Reply #99 on: November 04, 2014, 05:02:04 AM »
Interesting trio. Note particularly July 2014.
[]