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When will the Arctic Extent dip below 1,000,000 Km^2

2018-2019
12 (17.9%)
2020-2025
21 (31.3%)
2026-2030
13 (19.4%)
2031-2040
15 (22.4%)
2041-2060
2 (3%)
2061-2080
0 (0%)
2081-2099
1 (1.5%)
2100-beyond
3 (4.5%)

Total Members Voted: 64

Voting closed: July 27, 2018, 07:46:32 AM

Author Topic: When will the Arctic Go Ice Free?  (Read 187405 times)

oren

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Re: When will the Arctic Go Ice Free?
« Reply #1500 on: April 13, 2020, 02:48:37 PM »
My hunch is that it will take longer than most people think for the third tier to melt out and result in BOE. I don't understand the process by which sufficient heat reaches N of 85N to create a BOE. AGW is certainly moving us in that direction, but the degree of difficulty seems to be much higher for the last 4M km2 of extent.
I think the mechanism exists and is quite simple - export. A lot of the ice could one year float to the Fram and the Barents. The CAA-Greenland crack has shown that the ice does not always bunch against the islands, but can float free depending on the vagaries of wind.
Once the ice is thinned and shrunk enough by export, a GAC could arrive to finish the job. I think the first BOE will follow such a scenario.

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #1501 on: April 13, 2020, 03:55:05 PM »
I think the current distinction of a two tiered Arctic (Peripheral vs. High Arctic) is somewhat helpful, but not nearly as good as a three-tiered Arctic.

In the absence of having data available which differentiates according to likelihood of melt, it seems at least the geographic Central Basin should be seen as qualitatively different than the rest of the High Arctic and considered as a separate third tier.
At one time I wanted to have the CAB as a sort of third tier.

I also wanted to have the sea ice area, extent, and volume analysed on the same basis. This  works for my split into the two tiers. Unfotunately, due to a history that includes the late lamented "cryosphere today", the High Arctic Seas in Wipneus's volume data have different boundaries from that in the NSIDC area and extent data. The area named the Central Arctic Sea in the NSIDC data is 3.224 million km2, in the volume data the Central Arctic Basin (CAB) has an area somewhat larger. See Oren's post several posts back

NSIDC's Central Arctic Sea boundary is drawn much closer to 80 North. The CAB stretches a bit farther out (except at the boundary with the Barents / Greenland Seas).

And that's the way it is. And with my ancient laptop, rationed internet data in a place where a 4g signal is greeted with screams of joy, that's my limit.

« Last Edit: April 13, 2020, 07:12:33 PM by gerontocrat »
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The Walrus

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Re: When will the Arctic Go Ice Free?
« Reply #1502 on: April 13, 2020, 03:56:19 PM »
My hunch is that it will take longer than most people think for the third tier to melt out and result in BOE. I don't understand the process by which sufficient heat reaches N of 85N to create a BOE. AGW is certainly moving us in that direction, but the degree of difficulty seems to be much higher for the last 4M km2 of extent.

Maybe it will take longer, but a mechanism for transferring the necessary heat already exists in the form of warm water currents. As the ice retreats, the warm currents should follow the ice edge, leading to Atlantification ever further north.

As has been thrashed out, bathymetry is important, and the struggle between the ice and the halocline on the one hand and the warm ocean currents on the other turns very much in favor of the former as the bottom drops away north of 80 parallel, hence the correlation between bathymetry and ice front that is often (but not always) quite good.

But the warm surface currents keep battering the ice front - it is in the nature of warmer ocean waters to float on top, although not as strong as the tendency of the fresh water lense under the ice. But once Atlantification starts removing the fresh water lense, the surface waters should have it easier battering the ice front.

Or not. The mechanism is there (the warm ocean currents), but with support from bathymetry, perhaps the ice will hold out much longer than linear extrapolation would indicate.

The warm currents appear to be losing out to the Beaufort gyre, which has been expanding in recent years.  The gyre has been spinning faster and retaining the cold water and sea ice trapped within.  Consequently, the flow of clod water and ice out of the central arctic basin has slowed in recent years, and as a result, melt has decreased.  This "third tier" is behaving quite differently from the rest of the Arctic.

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #1503 on: April 13, 2020, 06:51:25 PM »
My hunch is that it will take longer than most people think for the third tier to melt out and result in BOE. I don't understand the process by which sufficient heat reaches N of 85N to create a BOE. AGW is certainly moving us in that direction, but the degree of difficulty seems to be much higher for the last 4M km2 of extent.

Maybe it will take longer, but a mechanism for transferring the necessary heat already exists in the form of warm water currents. As the ice retreats, the warm currents should follow the ice edge, leading to Atlantification ever further north.

As has been thrashed out, bathymetry is important, and the struggle between the ice and the halocline on the one hand and the warm ocean currents on the other turns very much in favor of the former as the bottom drops away north of 80 parallel, hence the correlation between bathymetry and ice front that is often (but not always) quite good.

But the warm surface currents keep battering the ice front - it is in the nature of warmer ocean waters to float on top, although not as strong as the tendency of the fresh water lense under the ice. But once Atlantification starts removing the fresh water lense, the surface waters should have it easier battering the ice front.

Or not. The mechanism is there (the warm ocean currents), but with support from bathymetry, perhaps the ice will hold out much longer than linear extrapolation would indicate.

The warm currents appear to be losing out to the Beaufort gyre, which has been expanding in recent years.  The gyre has been spinning faster and retaining the cold water and sea ice trapped within.  Consequently, the flow of clod water and ice out of the central arctic basin has slowed in recent years, and as a result, melt has decreased.  This "third tier" is behaving quite differently from the rest of the Arctic.
I see no slowdown in the reduction in late summer sea ice in both the Central Arctic Sea and the Beaufort as recorded in the NSIDC Area data.

It is true that there looks like a step change in the Central Arctic in 2007 making north of 80 look much more vulnerable to summer ice loss. The Beaufort looks as though, if conditions are right, it could melt out as near as dammit 100% in any year from now on.
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mitch

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Re: When will the Arctic Go Ice Free?
« Reply #1504 on: April 13, 2020, 07:11:59 PM »
Phoenix:
Removing the fresh water lens happens by mixing the deeper "warm" salty Atlantic waters upward into the fresher surface layer. This requires relatively large storms and no ice, since the density gradient is large.  Once the mixing is greater than the freshwater delivery, the surface warms up. 

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Re: When will the Arctic Go Ice Free?
« Reply #1505 on: April 13, 2020, 07:31:46 PM »

At one I wanted to have the CAB as a sort of third tier.

I also wanted to have the sea ice area, extent, and volume analysed on the same basis. This  works for my split into the two tiers. Unfotunately, due to a history that includes the late lamented "cryosphere today", the High Arctic Seas in Wipneus's volume data have different boundaries from that in the NSIDC area and extent data. The area named the Central Arctic Sea in the NSIDC data is 3.224 million km2, in the volume data the Central Arctic Basin (CAB) has an area somewhat larger.

NSIDC's Central Arctic Sea boundary is drawn much closer to 80 North. The CAB stretches a bit farther out (except at the boundary with the Barents / Greenland Seas).

And that's the way it is. And with my ancient laptop, rationed internet data in a place where a 4g signal is greeted with screams of joy, that's my limit.

Gerontocrat, thank you for your explanation of the different definitions of the Central Arctic. My comments about the desirability of a 3rd tier are not meant as a criticism of you. My OP acknowledges the limitations placed by the institutional definitions that you are stuck with.

I'm just trying to point out that there may be no utility in projecting a BOE based upon a two tiered understanding of the Arctic.

While I'm far from certain, I'm proposing the possibility that ice N of 80N which is sitting above deep water and far  from land masses (other than snow covered Greenland which doesn't supply a lot of heat advection to the CAB) is a much more resilient animal which will last much longer than the rest of the "High Arctic". I'm basing this possibility upon observation to date. In the absence of data which measures the relationship of sea ice minima to bathymetry and proximity to land, I'm just throwing out an anecdotal argument.

« Last Edit: April 13, 2020, 07:38:25 PM by Phoenix »

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Re: When will the Arctic Go Ice Free?
« Reply #1506 on: April 13, 2020, 07:41:59 PM »
Gerontocrat, your graphs appear to support my contention.  Since the step change in 2007, the trend is flat.

Phoenix

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Re: When will the Arctic Go Ice Free?
« Reply #1507 on: April 13, 2020, 07:52:44 PM »
My hunch is that it will take longer than most people think for the third tier to melt out and result in BOE. I don't understand the process by which sufficient heat reaches N of 85N to create a BOE. AGW is certainly moving us in that direction, but the degree of difficulty seems to be much higher for the last 4M km2 of extent.
I think the mechanism exists and is quite simple - export. A lot of the ice could one year float to the Fram and the Barents. The CAA-Greenland crack has shown that the ice does not always bunch against the islands, but can float free depending on the vagaries of wind.
Once the ice is thinned and shrunk enough by export, a GAC could arrive to finish the job. I think the first BOE will follow such a scenario.

Oren, I think you are certainly putting forth a plausible theory about how BOE could come about. Now the question is translating that to a prediction as this thread asks us WHEN the Arctic will go ice free. Both the unprecedented export and a GAC which has happened once represent exceptional weather events which seem to be not easily predictable. How does one even begin to predict the confluence of these two events happening together in the near future?


Hefaistos

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Re: When will the Arctic Go Ice Free?
« Reply #1508 on: April 13, 2020, 08:05:59 PM »
...
But IFF** that linear trend continues, by 2050 85% of the ice is gone, and by 2060 the Arctic would be virtually ice-free apart from some bits and pieces in winter.

Thanks Geron.
You are indulging in making projections based on historic data, that has a trend, and seasonal patterns.
it would be very helpful to also get the standard deviations of your projections revealed!
As it is now, you present one projection but we have no idea what the probability distribution looks like for different future dates. Only that it's bounded below to zero...

It's easy enough in Excel to calculate sd's.
I could add all sorts of fancy what-ifs, maybes and sensitivity analyses but this would simply distract from the message - which is - this is the road we have traveled on, are travelling on, and will travel on unless something changes not just substantially, but dramatically. If covid-19 results in a long-term Global Recession with CO2 emissions 30% lower than today, atmospheric CO2 ppm will continue to rise - just a bit less fast.

A warmer Arctic means less ice. Less ice means a warmer Arctic.

Nevertheless, I expect I will be digging around trying to find new ways of looking at & in the data for some time to come. Lock-Down Rules, OK!

What I mean, is that projections are inherently erroneous. If you curve-fit based on data at a certain point of time and then look at the projection it will give you one possible realization of the future - out of zillions of possible realizations. As time goes by, this guess-work is updated, we get new projections.

Thus, it's essential to understand how likely the various projections are to happen. What is the spread of your predictions of e.g. ice volume? Or in other words, what is the quality of the guesswork? To answer that question we use statistics, and specifically standard deviations.

What you would do concretely, is to look at the various projections at various data points and then check against the actual data of what happened in reality. From this you get the (continous) error of projection. And that in turn can be easily presented and displayed in terms of sd's, as error bands.

It would take some work in Excel to set up, but once it's done it's of course updated automatically.
« Last Edit: April 13, 2020, 08:14:27 PM by Hefaistos »

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Re: When will the Arctic Go Ice Free?
« Reply #1509 on: April 13, 2020, 08:06:33 PM »
Phoenix:
Removing the fresh water lens happens by mixing the deeper "warm" salty Atlantic waters upward into the fresher surface layer. This requires relatively large storms and no ice, since the density gradient is large.  Once the mixing is greater than the freshwater delivery, the surface warms up.

There seems to be a chicken and egg element to the discussion. We're discussing the mechanism by which the Arctic becomes relatively ice free. It doesn't make sense that there must be no ice as a precondition to the mixing which gives rise to the reduction of ice.

The 2012 GAC provides I think the best example of a storm mixing up the layers when the amount of open water was close to a peak. That's a scenario for major melt within a particular melt season. But the fresh water lens seems to be replenished during the winter when the High Arctic freezes and in the spring when the continental snow melt runs into the Arctic via river runoff.


oren

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Re: When will the Arctic Go Ice Free?
« Reply #1510 on: April 13, 2020, 08:32:33 PM »
Now the question is translating that to a prediction as this thread asks us WHEN the Arctic will go ice free. Both the unprecedented export and a GAC which has happened once represent exceptional weather events which seem to be not easily predictable. How does one even begin to predict the confluence of these two events happening together in the near future?
Unfortunately, an August GAC has happened not once but twice - 2012 and 2016. The results are clearly visible in Gero's chart above, NSIDC CAB area.
In addition to strong export, a very warm melt season is also on the menu, we had such a whole season in 2012 and in the early to middle part of 2019.
IMHO the chances of a BOE for a given year are currently somewhat less than 10% per year, maybe 5%, and growing. I would be very surprised if a BOE does not happen by 2030.

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #1511 on: April 13, 2020, 09:33:25 PM »
I'm just trying to point out that there may be no utility in projecting a BOE based upon a two tiered understanding of the Arctic.

While I'm far from certain, I'm proposing the possibility that ice N of 80N which is sitting above deep water and far from land masses (other than snow covered Greenland which doesn't supply a lot of heat advection to the CAB) is a much more resilient animal which will last much longer than the rest of the "High Arctic". I'm basing this possibility upon observation to date. In the absence of data which measures the relationship of sea ice minima to bathymetry and proximity to land, I'm just throwing out an anecdotal argument.
"no utility" ? I beg to differ. Some utility ? - my post seems to have provoked a lot of responses containing suggestions and possibilities on "what happens next".

Any projection to 2050 must have limited value, as reality must differ and that linear relationship must break down sometime or other. But my post did serve its purpose, which was to suggest that using 2100 as the end date in IPCC deliberations is, in my view, pretty dumb as far as Arctic Sea Ice is concerned.

And talking of linear relationships breaking down, perhaps covid-19 and how humanity deals with it could be the trigger that causes the breakdown, for good or ill.

That's it for crystal ball gazing from me at the moment; back to the short-term.
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Re: When will the Arctic Go Ice Free?
« Reply #1512 on: April 13, 2020, 10:12:44 PM »
I'll certainly agree with you that the IPCC looking at Arctic Sea Ice in the context of year 2100 levels is worthless.

I lean toward the doomer side of things. My position that BOE will be much later than most might be one that could superficially be interpreted as an indication of a denier. On the contrary, I think the ice loss we've already seen can be categorized as catastrophic. If we hit something near 2.0M km2 extent (double the BOE threshold), I'd characterize that as perhaps an indication of reaching an apocalyptic phase.
« Last Edit: April 14, 2020, 12:03:09 PM by Phoenix »

binntho

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Re: When will the Arctic Go Ice Free?
« Reply #1513 on: April 14, 2020, 06:44:27 AM »

.....But once Atlantification starts removing the fresh water lense.....


Perhaps you can expand on this piece. My understanding is that the fresh water is the surface layer of the Arctic because it is less dense than warmer Atlantic water because the salinity impacts density more than the temperature difference. Incoming Atlantic water does not generally displace the surface layer, it exists beneath it.

The process of removing the fresh water lens that you refer to isn't clear.

Note: Fresh water exits the Arctic all the time via Fram Strait and enters via river runoff. How would "Atlantification" accelerate the departure of fresh water?

Good points, and I won't pretend that I know more than a smidgeon of any potential answers. But I'll try anyway!

The density of water changes with salt content and temperature. So a cold fresh water layer that competes with a salty warm current is not obviously going to win. The whole AMOC concept of the warm surface currents steadily getting colder until they start to sink does not assume that it is the fresh-water lense that pushes it down. With the ongoing increase in air and ocean temperature, any sinking tendency of the warm surface waters is going to steadily decrease.

"Atlantification" is what scientists have apparently called the changes that have happened in the Barents as it has transitioned from a mostly ice covered sea to mostly ice free. As I understand it, wave and wind action mixes the waters sufficiently to remove the "fresh" water surface that can freeze rapidly.

As for the fresh water lense - in my understanding, this exists under the ice in winter and is added to by summer melt, but once the ice is gone, wave action has the potential to break up this lens and increase mixing from below. This of course is entirely dependent on there being a big enough area of open water to generate decent wave activity, and that bathymetry allows for there to be any significant deeper layers to mix with.

So if we call it "Atlantification" when wave action mixes the surface fresh waters with deeper salty (and warm) waters, then clearly this will not happen over the Siberian shelf or, in any near future, along the CAA coast. But the entire Atlantic front, as well as a decent enough part of the Pacific front, should be open to this process.

So is there a natural barrier to this process of Atlantification along the Atlantic front? Perhaps. Or perhaps it's simply a creeping ongoing change that is steadily working it's way northwards.
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Tom_Mazanec

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Re: When will the Arctic Go Ice Free?
« Reply #1514 on: April 14, 2020, 10:18:37 AM »
I'll certainly agree with you that the IPCC looking at Arctic Sea Ice in the context of year 2100 levels is worthless.

I lean toward the doomer side of things. My position that BOE will be much later than most might be one that could superficially be interpreted as an indication of a denier. On the contrary, I think the ice loss we've already seen can be categorized as catastrophic. If we hit something near 2.0M km2 extent (double the BOE threshold), I'd characterize that as perhaps an indication of reaching an apocalyptic phase.
Good point. People are too fixated on 1 M sq.km. as a binary dividing line. You get cataclysmic changes in the Arctic with substantially more than that. Catastrophe is not a yes/no function.
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Hefaistos

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Re: When will the Arctic Go Ice Free?
« Reply #1515 on: April 14, 2020, 01:36:48 PM »
I'm just trying to point out that there may be no utility in projecting a BOE based upon a two tiered understanding of the Arctic.

While I'm far from certain, I'm proposing the possibility that ice N of 80N which is sitting above deep water and far from land masses (other than snow covered Greenland which doesn't supply a lot of heat advection to the CAB) is a much more resilient animal which will last much longer than the rest of the "High Arctic". I'm basing this possibility upon observation to date. In the absence of data which measures the relationship of sea ice minima to bathymetry and proximity to land, I'm just throwing out an anecdotal argument.
"no utility" ? I beg to differ. Some utility ? - my post seems to have provoked a lot of responses containing suggestions and possibilities on "what happens next".

Any projection to 2050 must have limited value, as reality must differ and that linear relationship must break down sometime or other. But my post did serve its purpose, which was to suggest that using 2100 as the end date in IPCC deliberations is, in my view, pretty dumb as far as Arctic Sea Ice is concerned.

And talking of linear relationships breaking down, perhaps covid-19 and how humanity deals with it could be the trigger that causes the breakdown, for good or ill.

That's it for crystal ball gazing from me at the moment; back to the short-term.


Statistically speaking, any specific projection is 'worthless', as it is just one possible realization out of a zillion of possible outcomes.
In order to claim that e.g. IPCC's projection is more 'dumb' than our honoured Gerontocrat's, we need to see in which bucket of standard deviations the various projections would fall.
Easy enough, just a recursive evaluation of forecasts done compared to actual outcomes.

Example: If IPCC's projection turns out to be a 3 sigma event (1% likelihood) whereas Gerontocrat's turns out to be within 1 sigma, we can say that IPCC made a more extreme forecast than G.

The Walrus

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Re: When will the Arctic Go Ice Free?
« Reply #1516 on: April 14, 2020, 03:19:15 PM »
I'll certainly agree with you that the IPCC looking at Arctic Sea Ice in the context of year 2100 levels is worthless.

I lean toward the doomer side of things. My position that BOE will be much later than most might be one that could superficially be interpreted as an indication of a denier. On the contrary, I think the ice loss we've already seen can be categorized as catastrophic. If we hit something near 2.0M km2 extent (double the BOE threshold), I'd characterize that as perhaps an indication of reaching an apocalyptic phase.

I have been called the same, when I post that a BOE is unlikely this decade.  That does not mean that the sea ice is not shrinking.  The aforementioned two- or three-tiered approaches show that the ice most susceptible to melt has indeed been melting rapidly.  That ice confined to the CAB (and others) has been shown to be more resilient to melt.  Consequently, it has taken a more extensive event to melt large sections of this ice.  This has led to greater annual fluctuations, as Gerontocrat shows.  Any extrapolations based largely on the easily melted ice sheets are prone to failure. 

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Re: When will the Arctic Go Ice Free?
« Reply #1517 on: April 14, 2020, 06:15:26 PM »
So is there a natural barrier to this process of Atlantification along the Atlantic front? Perhaps. Or perhaps it's simply a creeping ongoing change that is steadily working it's way northwards.

I think that natural barrier is made up of Svalbard, FJI and Severnaya Zemlya as these islands serve to constrict ice from exiting the Arctic into the Barents and thus preserve the fresh water lens.

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Re: When will the Arctic Go Ice Free?
« Reply #1518 on: April 14, 2020, 10:45:11 PM »
.....People are too fixated on 1 M sq.km. as a binary dividing line. You get cataclysmic changes in the Arctic with substantially more than that.

That's my opinion as well, but I would be interested in hearing from others to ascertain the degree of agreement there is around this point.

From the perspective of the larger discussion around AGW and ecological breakdown, the focus on BOE doesn't seem to be an especially important topic. It's certainly an academically interesting topic,  but not necessarily an important one unless there are people who think that we'll have a reasonably habitable planet with say 2M km2 of sea ice at the minimum.

My personal bias would be for the discussion to orbit around the nearer term milestones and their consequences for life on earth vs. a milestone which represents a point which may be well beyond massive habitability loss.






oren

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Re: When will the Arctic Go Ice Free?
« Reply #1519 on: April 14, 2020, 11:15:49 PM »
I can't say much about planetary habitability and all that. However for me personally extent is a somewhat meaningless number. My own BOE criterion is <1M km2 of AMSR2 area. And the main physical marker should be a spike of DMI N of 80 temps to 275k and above during summer. This IMHO is more important than the arbitrary 1M criterion. It would mean that the ASI can't cool the Arctic enough.

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Re: When will the Arctic Go Ice Free?
« Reply #1520 on: April 15, 2020, 12:07:11 AM »
One million square km is largely symbolic.  Similar to 2C temperature rise.  There is no real significance to those values, except that they were chosen to represent targets in the fight against climatic change. 

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Re: When will the Arctic Go Ice Free?
« Reply #1521 on: April 15, 2020, 12:25:42 AM »
One million square km is largely symbolic.  Similar to 2C temperature rise.  There is no real significance to those values, except that they were chosen to represent targets in the fight against climatic change.

I'll agree with 1.5C or 2.0C as well established IPCC targets attached to consequences, but who thinks extent of 1M km2 is a "target" in the fight against climate change? 

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Re: When will the Arctic Go Ice Free?
« Reply #1522 on: April 15, 2020, 03:46:48 AM »
I understand we had problems even in 2012 re Hurricane Sandy from the low Arctic Sea Ice of that year.
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Re: When will the Arctic Go Ice Free?
« Reply #1523 on: April 15, 2020, 03:48:55 AM »
I suppose i'll add my two bits.

I think its good to have something to stick to, to define what a BOE is. I.e. the 1 million threshold. It obviously doesn't really mean a whole lot, however, it gives us something to refer too. I have come to the conclusion that whether or not the ice melts below that number between now and 2050 probably won't change the outcome for our civilization. What the current pandemic has shown, is the entire system is very fragile. We aren't even in the summer yet for the northern hem. once the chaotic weather comes, we are in for a true wake up.

The more the ice melts, the more screwed we are in the near term. All we can do is follow the data. I do think there is a good chance we go below 1 mil. km2 this decade though, just based off the volume data

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Re: When will the Arctic Go Ice Free?
« Reply #1524 on: April 15, 2020, 04:20:15 AM »
What the current pandemic has shown, is the entire system is very fragile

If by "system" you mean our human civilisation, then I would disagree. For me it is has been a very big surprise to see how resilient the "system" is to these extreme circumstances.
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Re: When will the Arctic Go Ice Free?
« Reply #1525 on: April 15, 2020, 04:25:05 AM »
What the current pandemic has shown, is the entire system is very fragile

If by "system" you mean our human civilisation, then I would disagree. For me it is has been a very big surprise to see how resilient the "system" is to these extreme circumstances.
Covid is straining our “system” even though it is less than what the Black Death was, or what AGW could be in another generation.
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Wherestheice

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Re: When will the Arctic Go Ice Free?
« Reply #1526 on: April 15, 2020, 04:29:46 AM »
What the current pandemic has shown, is the entire system is very fragile

If by "system" you mean our human civilisation, then I would disagree. For me it is has been a very big surprise to see how resilient the "system" is to these extreme circumstances.

The only reason it appears resilient, is because everything is shut down. Once this all blows over, there will be a lot of wounds. Just another step towards the eventual collapse. This is just my opinion though.
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Re: When will the Arctic Go Ice Free?
« Reply #1527 on: April 15, 2020, 04:42:35 AM »
There is a separate Covid-19 thread which has plenty of action. The focus on that topic these days is certainly understandable, but it's a temporary issue that will likely pass with a vaccine in a few years.

There is no vaccine for AGW tipping points and IMO, the virus adaptation isn't a great benchmark for human resiliency to AGW or more specifically, extreme Arctic amplification.

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Re: When will the Arctic Go Ice Free?
« Reply #1528 on: April 15, 2020, 04:44:19 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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Phoenix

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Re: When will the Arctic Go Ice Free?
« Reply #1529 on: April 15, 2020, 04:57:19 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.

Which is the best ASIF thread for general collapse discussion?

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Re: When will the Arctic Go Ice Free?
« Reply #1530 on: April 15, 2020, 05:17:38 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.

I agree with you binntho.  Humans are rather resilient.

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Re: When will the Arctic Go Ice Free?
« Reply #1531 on: April 15, 2020, 05:40:45 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.

I agree with you binntho.  Humans are rather resilient.

Compared to which other species? Homo sapiens have ~ 10k generations under our belts. Alligators have millions of generations of similar length. Geologically speaking, we're a flash. And our destructive power is off the charts compared to other species.


Glen Koehler

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Re: When will the Arctic Go Ice Free?
« Reply #1532 on: April 15, 2020, 06:45:07 AM »

While I'm far from certain, I'm proposing the possibility that ice N of 80N which is sitting above deep water and far  from land masses (other than snow covered Greenland which doesn't supply a lot of heat advection to the CAB) is a much more resilient animal which will last much longer than the rest of the "High Arctic". I'm basing this possibility upon observation to date. In the absence of data which measures the relationship of sea ice minima to bathymetry and proximity to land, I'm just throwing out an anecdotal argument.

     Sorry to repeat an upthread post - but there are data to address the "High Arctic will hold on longer" hypothesis:
    A linear trend line of whole-Arctic September Volume shows a decline from 11.1 to 4.2 K Km3 (edit)  a 62% decline from 2000 to 2019..

    For the CAB alone volume declined 55% , for the same time period (from 8.4 to 3.8 K km3).  So while the CAB lost volume at a slightly slower rate, it was not much slower.

     I think this argues against the idea that progression towards a largely ice-free September (followed by August, October, July) will be stalled because the final ice refuge is at too high a latitude.

      The Sept. ice is not centered around 90N anyway, but is centered south of 90N on the Greenland/Canadian side.  The location of the remaining Sept. ice does not match bathymetry very well.  So I don't see that as a saving grace either.  Protection by location matters even less when you factor in the increasing mobility of thinning ice, reduction of land-fast ice, increased open water/wind fetch, increased warm air incursion, and increased melt season storm potential as greenhouse gas loading and global heating exacerbated by Arctic amplification continue.
« Last Edit: April 15, 2020, 07:44:33 AM by Glen Koehler »

binntho

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Re: When will the Arctic Go Ice Free?
« Reply #1533 on: April 15, 2020, 07:20:32 AM »
      The Sept. ice is not centered around 90N anyway, but is centered south of 90N on the Greenland/Canadian side.  The location of the remaining Sept. ice does not match bathymetry very well.  So I don't see that as a saving grace either.  Protection by location matters even less when you factor in the increasing mobility of thinning ice, reduction of land-fast ice, increased open water/wind fetch, increased warm air incursion, and increased melt season storm potential as greenhouse gas loading and global heating exacerbated by Arctic amplification continue.

Absolutely!
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Re: When will the Arctic Go Ice Free?
« Reply #1534 on: April 15, 2020, 07:35:58 AM »

While I'm far from certain, I'm proposing the possibility that ice N of 80N which is sitting above deep water and far  from land masses (other than snow covered Greenland which doesn't supply a lot of heat advection to the CAB) is a much more resilient animal which will last much longer than the rest of the "High Arctic". I'm basing this possibility upon observation to date. In the absence of data which measures the relationship of sea ice minima to bathymetry and proximity to land, I'm just throwing out an anecdotal argument.

     Sorry to repeat an upthread post - but there are data to address the "High Arctic will hold on longer" hypothesis:
    A linear trend line of whole-Arctic September Volume shows a decline from 11.1 to 4.2 M Km3  a 62% decline from 2000 to 2019..

    For the CAB alone volume declined 55% , for the same time period (from 8.4 to 3.8 M km3).  So while the CAB lost volume at a slightly slower rate, it was not much slower.

     I think this argues against the idea that progression towards a largely ice-free September (followed by August, October, July) will be stalled because the final ice refuge is at too high a latitude.

      The Sept. ice is not centered around 90N anyway, but is centered south of 90N on the Greenland/Canadian side.  The location of the remaining Sept. ice does not match bathymetry very well.  So I don't see that as a saving grace either.  Protection by location matters even less when you factor in the increasing mobility of thinning ice, reduction of land-fast ice, increased open water/wind fetch, increased warm air incursion, and increased melt season storm potential as greenhouse gas loading and global heating exacerbated by Arctic amplification continue.

Thanks for your post. A few points in reply.

1) Do you have the CAB volume data by year from 2000 on to share?

2) You are using an upper case "M" for your volume measurements. This is generally representing millions. I think you meant to use a "k" for thousands of km3 in volume.

3) The hypothesis of the remaining ice at minima is that the more resilient ice is based upon two criteria. 1) Bathymetry AND 2) Distance from a large heat advecting land mass. The second criteria is the more dominant variable and has a tad more nuance. Greenland should not be considered a large heat advecting land mass because it is covered in snow year round and doesn't experience heat waves like Alaska and Siberia which project heat well into the ocean. 

At the September minimum, there is no ice adjacent to Alaska, Siberia, Scandinavia or the Canadian continent which bleeds heat into the southern portion of the CAA. Greenland is the only large land mass which has ice adjacent to it and the theory attributes this to Greenland being a cold land mass. Pretty self explanatory.

Bathymetry is more relevant is trying to understand how far the Atlantic and Pacific intrude into the CAB. On the Atlantic side, there seems to be a pause at ~ 82N which corresponds to the area where the bathymetry shifts from the shallow Barents Shelf to the deep Nansen Basin. The most northern areas of the Beaufort and ESS have also been more resilient due to the combination of depth and distance from land.

4) My limited understanding of the volume data is that the record low volume was set in 2012. If you are correct that the CAB volume declined by 55% from 2000 to 2019, then the decline from 2000 to 2012 would have been even greater than 55% with an increase since 2012. I don't have the numbers handy, so if you could provide that would be great.

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Re: When will the Arctic Go Ice Free?
« Reply #1535 on: April 15, 2020, 07:41:53 AM »
I agree with you binntho.  Humans are rather resilient.

    Different people in this discussion are defining the problem differently.  I agree that humans won't go extinct.  But wrecking the climate system we depend on to feed 7.5 billion people, forced migration from large areas of densely populated coastal areas, more forced migration by altered monsoon patterns, heat waves/flooding/drought etc. will lead to horrific consequences for many millions, and probably billions of human beings.  Humans will persist, but human civilization would/will suffer major involuntary evolution.

    And while I have the pulpit -- I agree that a 1 million km2 Sept. BOE definition is arbitrary, but it is not meaningless.  It serves as an important marker for when systemic change has passed an easily observable, intuitive (and thus politically significant), and functionally important milestone.  The threshold isn't zero because there will continue to a fraction of the original September Extent that hangs on much longer, but going below 1M km2 signifies a huge change from the preindustrial condition (the 1979-1984 average Sept. Extent was ca. 7.3M km2). 

     Comparing trend lines for Extent, Volume, and Thickness, and remembering that E = V/T, shows that when Extent reaches 1M km2, average Sept. Thickness will be at about 0.8 meter, and average Sept. Volume will be at about 0.8K km3.  The linear trend for volume decline indicates that there is a 50% chance of 0.8K km3 and Sept. BOE by 2029 (with a 95% confidence interval of 2024--2036), i.e. not long from now on our current trajectory.

     Extent is an incomplete measure of the status of the Arctic sea ice.  But an 87% reduction in September ice cover has major ecological and physical systemic consequences, such as the effect on subsequent ocean water insulation vs. heat exchange to the atmosphere leading into winter. 

      I suppose the albedo effect from Extent loss in September is probably minimal because the sun is so low in the Arctic sky by then, but once Sept. starts hitting "BOE", August will only be a few years behind.  And as August approaches 1M km2, that means that July is losing ice cover too.  The albedo impact from a reduction in ice cover Extent in August, and especially July, would have a strong effect on Arctic energy dynamics.

      More scary news: The current year to date global average surface temperature is running well ahead of where it "should" be, given that we are near the bottom of the solar cycle and in ENSO neutral territory.  Even accounting for incremental year-to-year warming from rising CO2e, 2020 should run a bit cooler than 2019 and well behind the current record holder for the warmest year in 2016.  But a projection for the final year-end 2020 average temperature is running just behind 2016 and ahead of 2019.  This suggests that the warming rate is accelerating.  None other than James Hansen noted the same in monthly NASA GISStemp message today. 

     As bad as the COVID pandemic is, all expectations are for it to subside within a few months (or a year or two at most).  If we disrupt the climate, the inertia of that system (ocean heat) and multi-decadal lag for surface weather impacts means we will be stuck with the damage for decades at the very least even with remedial GHG removals (for which we do not yet have scaleable methods), and more likely multiple centuries.  This is not a drill.  This is really happening.  I have to remind myself about that regularly because it is so hard to fathom. 

      It's a real morality tale. I agree with those who recognize the absolutely stunning pace of scientific knowledge acquisition and technological innovation occurring at the same time as we wreck the life support system of the only planet we have.  If we all pull in the same direction, and get rid of "leaders" who mislead, there is a chance for the disaster not to fully unfold.  But we are already too late to avoid the damage entirely as more than a little has already happened, and a lot more is coming in the next 20 years.

     
« Last Edit: April 15, 2020, 08:54:14 AM by Glen Koehler »

binntho

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Re: When will the Arctic Go Ice Free?
« Reply #1536 on: April 15, 2020, 07:55:06 AM »
2) Distance from a large heat advecting land mass. The second criteria is the more dominant variable and has a tad more nuance.

I'm not sure if being close to a landmass is better than being close to open ocean. The oceans absorb much more radiation than land, and the heat transfer of ocean currents has vastly larger potentiality than wind-driven heat transfer by air.
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Re: When will the Arctic Go Ice Free?
« Reply #1537 on: April 15, 2020, 08:02:56 AM »
<snip>
I agree with you binntho.  Humans are rather resilient.

Re: Humans are resilient.

Take away their technology and we'll see how resilient they are.
Then it's back to hunter-gatherer lifestyle in a very much degraded biosphere, with AGW accelerating and all previous knowledge of hunting-gathering and low technology lost. Physically most humans are a wreck compared to living nature animals.
They likely will start competing and use violence in stead of cooperating. Most social functions are lost and out of our cultures and languages.
Ergo: contemporary humans are not resilient at all in my opinion.

Humans have had their chance but civilisations and high technology wrecked it for good. Humanity is not an intelligent species. Slave to fantasies and went really wrong with its crazy supremacy over all other lifeforms.
It is high time this disastrous episode ends. Let Earth breath again! Let life flourish again!
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Re: When will the Arctic Go Ice Free?
« Reply #1538 on: April 15, 2020, 08:03:44 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.

It's clear we disagree here, but that is okay :)

I simply don't see civilization surviving the possible 4-6 C rise this century, I do think human societies can be rebuilt though in certain regions.
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binntho

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Re: When will the Arctic Go Ice Free?
« Reply #1539 on: April 15, 2020, 08:18:21 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.

It's clear we disagree here, but that is okay :)

I simply don't see civilization surviving the possible 4-6 C rise this century, I do think human societies can be rebuilt though in certain regions.

Well, lots of things have the capacity to totally wreck human civilisation. But I do not think it is remotely likely that it will happen this century, or that it will happen because of AGW. A rise of 4-6 degrees is not going to happen.

But a lot of people seem to have an apocalyptic deathwish on behalf of their fellow humans. Myself I find it a loathsome attitude.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Glen Koehler

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Re: When will the Arctic Go Ice Free?
« Reply #1540 on: April 15, 2020, 08:28:13 AM »
1) Do you have the CAB volume data by year from 2000 on to share?
       ***I pull Volume data from the twice monthly Wipneus PIOMAS updates.

I only have it by daily values.  Too many numbers to share and too late and not enough time to create a pivot table. 

CAB Sept. avg. Volume
2000:  8.370
2012:  3.399
2019:  3.794


2) You are using an upper case "M" for your volume measurements. This is generally representing millions. I think you meant to use a "k" for thousands of km3 in volume.
     ***ooops.    Thanks for catching that.  Now corrected.

3) The hypothesis of the remaining ice at minima is that the more resilient ice is based upon two criteria. 1) Bathymetry AND 2) Distance from a large heat advecting land mass. The second criteria is the more dominant variable and has a tad more nuance. Greenland should not be considered a large heat advecting land mass because it is covered in snow year round and doesn't experience heat waves like Alaska and Siberia which project heat well into the ocean. 

At the September minimum, there is no ice adjacent to Alaska, Siberia, Scandinavia or the Canadian continent which bleeds heat into the southern portion of the CAA. Greenland is the only large land mass which has ice adjacent to it and the theory attributes this to Greenland being a cold land mass. Pretty self explanatory.

Bathymetry is more relevant is trying to understand how far the Atlantic and Pacific intrude into the CAB. On the Atlantic side, there seems to be a pause at ~ 82N which corresponds to the area where the bathymetry shifts from the shallow Barents Shelf to the deep Nansen Basin. The most northern areas of the Beaufort and ESS have also been more resilient due to the combination of depth and distance from land.
   ***Lots of upthread discussion on bathymetry, e.g. https://forum.arctic-sea-ice.net/index.php/topic,2348.msg237718.html#msg237718.  I don't know enough to say anymore than that to my eye the pattern of current Sept. ice, and the distribution expected by experts for the last to melt ice to hug the CAA, does not appear to follow either bathymetry or distance from land

4) My limited understanding of the volume data is that the record low volume was set in 2012. If you are correct that the CAB volume declined by 55% from 2000 to 2019, then the decline from 2000 to 2012 would have been even greater than 55% with an increase since 2012. I don't have the numbers handy, so if you could provide that would be great.
***See #1.


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Re: When will the Arctic Go Ice Free?
« Reply #1541 on: April 15, 2020, 08:31:33 AM »
2) Distance from a large heat advecting land mass. The second criteria is the more dominant variable and has a tad more nuance.

I'm not sure if being close to a landmass is better than being close to open ocean. The oceans absorb much more radiation than land, and the heat transfer of ocean currents has vastly larger potentiality than wind-driven heat transfer by air.

As discussed upstream, the density gradient is a roadblock to ocean heat making it to the surface where the ice is located. The salt in the warm Atlantic ocean water makes it too dense. There's abundant heat in the Arctic Ocean lurking in the subsurface layer below the freshwater lens.

I agree that the air is a less efficient conduit for heat blowing over from a warmed earth. But there is no equivalent roadblock above the surface.

Look at the places that have ice remaining at the minima and explain what makes those places different than the locations which have no ice. I've just cobbled together a hypothesis from observation. It could all be just a coincidence, but I'm kicking the tires and willing to consider the possibility that we've run into a much more resilient layer.




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Re: When will the Arctic Go Ice Free?
« Reply #1542 on: April 15, 2020, 08:58:53 AM »

CAB Sept. avg. Volume
2000:  8.370
2012:  3.399
2019:  3.794[/b]

   ***Lots of upthread discussion on bathymetry, e.g. https://forum.arctic-sea-ice.net/index.php/topic,2348.msg237718.html#msg237718.  I don't know enough to say anymore than that to my eye the pattern of current Sept. ice, and the distribution expected by experts for the last to melt ice to hug the CAA, does not appear to follow either bathymetry or distance from land


Thanks for the data points Glen. Much appreciated.

I think if you look carefully, the projection that parts of the CAA will be the last with ice is appropriate and not inconsistent with the way my theory of things.

First, let's consider how we define "land" as a large heat advecting land mass. I'm not referring to small islands in the CAA. I'm referring to continents which are not covered in snow year round. The southern portion of the CAA which is adjacent to the N. American continent already melts out reliably each year. It's the northern portion which is 5+ degrees latitude north of the continent where the ice remains.

The ocean circulation to the northern CAA is also highly restricted for much of the year. And the impact of wind on the CAA is negligible relative to the open CAB.


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Re: When will the Arctic Go Ice Free?
« Reply #1543 on: April 15, 2020, 09:01:31 AM »
  I'll flaunt my ignorance one more time to say that I assume the current thickest September ASI, and last to melt residual ice, is along the northern edge of the CAA because the currents move the ice to pile up there.  Gerontocrat recently posted about the nooks and crannies of the CAA opening up and transitioning away from being a wall that allows ice to pile up, and into another gateway for ASI export southward into a lower latitude melting zone.  If so, yet another accelerating mechanism.  Melting begets melting.

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Re: When will the Arctic Go Ice Free?
« Reply #1544 on: April 15, 2020, 09:04:25 AM »
I guess apocoalypticists are constantly seeing signs of imminent collapse. And have been since at least Ramses' time. I on the other hand, who am absolutely certain that our human civilisation will survive both Covid-19 and AGW, see amazing resilience and innovative adaptation everywhere.

It's clear we disagree here, but that is okay :)

I simply don't see civilization surviving the possible 4-6 C rise this century, I do think human societies can be rebuilt though in certain regions.

Well, lots of things have the capacity to totally wreck human civilisation. But I do not think it is remotely likely that it will happen this century, or that it will happen because of AGW. A rise of 4-6 degrees is not going to happen.

But a lot of people seem to have an apocalyptic deathwish on behalf of their fellow humans. Myself I find it a loathsome attitude.

Nobody can predict the future, but to say a rise of 4-6 C is not going to happen...... all I can say is the science disagrees. It is most certainly in the realm of possiblity, unless some unforseen circumstance appears.
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Re: When will the Arctic Go Ice Free?
« Reply #1545 on: April 15, 2020, 09:33:57 AM »
RE:  CAB Sept. Volume data
  I think those values may be the minimum daily values, not the September average values. 
But that doesn't change the resulting inferences much.
2000:  8.370
2012:  3.399
2019:  3.794

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Re: When will the Arctic Go Ice Free?
« Reply #1546 on: April 15, 2020, 10:23:39 AM »
Here are two of my old graphs that can shed light on the CAB volume. One can see how 2010 was a major change, and 2012 coming at the end of 3 low years was possibly a semi-fluke (when examined using other metrics this becomes more pronounced). However following the correction of 2013-2014 the trend has gone lower again, with record lows being made all the way to mid-Aug.
Taking the long view, the trend is IMHO certainly still there, though possibly slower.

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Re: When will the Arctic Go Ice Free?
« Reply #1547 on: April 15, 2020, 01:57:53 PM »
Here are two of my old graphs that can shed light on the CAB volume. One can see how 2010 was a major change, and 2012 coming at the end of 3 low years was possibly a semi-fluke (when examined using other metrics this becomes more pronounced). However following the correction of 2013-2014 the trend has gone lower again, with record lows being made all the way to mid-Aug.
Taking the long view, the trend is IMHO certainly still there, though possibly slower.

That second chart is great Oren. I hadn't known 2010/11 were also such low years. Very easy to see the trend. Would be interesting to see a line for day ~ 255 (mid Sept)  if its available.

It's something of a Rorschach test. If you look from 2000-2010, it looked like it was headed to zero by 2020. If one is inclined to think we hit something of a wall around 3.5k km3, they might find support for it there as well.

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Re: When will the Arctic Go Ice Free?
« Reply #1548 on: April 15, 2020, 03:12:24 PM »
Here are two of my old graphs that can shed light on the CAB volume. One can see how 2010 was a major change, and 2012 coming at the end of 3 low years was possibly a semi-fluke (when examined using other metrics this becomes more pronounced). However following the correction of 2013-2014 the trend has gone lower again, with record lows being made all the way to mid-Aug.
Taking the long view, the trend is IMHO certainly still there, though possibly slower.

That second chart is great Oren. I hadn't known 2010/11 were also such low years. Very easy to see the trend. Would be interesting to see a line for day ~ 255 (mid Sept)  if its available.

It's something of a Rorschach test. If you look from 2000-2010, it looked like it was headed to zero by 2020. If one is inclined to think we hit something of a wall around 3.5k km3, they might find support for it there as well.

It is tempting to extrapolate from that chart.  The extrapolations will differ significantly, depending on the start and end points.  The overall linear trend is -0.26k km3/year.  Focusing on the first part yields a downward trend of -0.44k km3/yr.  The trend from 2014 forward exactly matches that trend, just offset by ~3k.  Will the trend continue for another six years, breaking through the wall around 3.5k km3, and falling below 1 km3?  Will it then bump upwards again?  Alternatively, the trend since 2010 is +0.001k km3/year.  Could the wall around that level for several years?  There are many possibilities.

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Re: When will the Arctic Go Ice Free?
« Reply #1549 on: April 15, 2020, 04:37:56 PM »
RE:  CAB Sept. Volume data
  I think those values may be the minimum daily values, not the September average values. 
But that doesn't change the resulting inferences much.
2000:  8.370
2012:  3.399
2019:  3.794

If we look at that decline on a logarithmic scale, sea ice declined about 7% per year from 2000 to 2012. [8.4k * (1-.07)^12] ~ 3.4k.

In order to get from 3.8k in 2019 to 1.0k (~BOE level) in 2030, we'll need to see a decline of 11-12% per year.

In order to hit BOE by 2030, we'd need to a substantially larger proportion of the remaining ice disappear going forward than we saw even in the accelerated 2000-2012 period.