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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 115415 times)

Peter Ellis

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Re: When will the Arctic Go Ice Free?
« Reply #550 on: July 15, 2019, 02:42:53 PM »
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.

Sam

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Re: When will the Arctic Go Ice Free?
« Reply #551 on: July 15, 2019, 02:54:47 PM »
Peter,

I disagree on several counts.

The “we” in both cases is a generic we of unassigned humanity looking at the problem.

More than that I reject flatly your assertion that members of this community are “more alarmist”.

“More alarmed” is correct. “Alarmist” as used in English today is a derogatory valuation of the state of alarm. Far from being alarmist, the vast majority of those participating in this forum are stark realists. Alarm in the context you use it is generally a statement about something the writer takes as being a wrong headed and unjustified emotional reaction.

Clearly many of us are having emotional reactions to the terrifying changes we are seeing and to the most likely consequences of those observed changes and trends. That does not make them “alarmist” statements in the pejorative sense that you seem to intend.

I find it more concerning that this sort of language use has become the stock and trade of political and financial interests hell bent on maintaining their rapacious ways without regard to the consequences.

And there’s is in my opinion no place for that in the discussion.

Sam

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #552 on: July 15, 2019, 03:16:25 PM »
23rd August 2027.
End of debate.
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Simon

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Re: When will the Arctic Go Ice Free?
« Reply #553 on: July 15, 2019, 03:24:04 PM »
When the Arctic goes very low early September looks as though it depends upon the volume at maximum. It seems that if the max volume is below 18 000km3 then there is a good chance of a BOE occurring. Then in any given season, the rate of ice loss would depend upon weather, insolation etc. So, perhaps a September virtually ice free arctic may depend on poor autumn winter recovery. Does this make sense?

Shared Humanity

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Re: When will the Arctic Go Ice Free?
« Reply #554 on: July 15, 2019, 03:33:02 PM »
On the science, if the observations are not clear enough on an effect then there may still be an effect and it will almost certainly get worse with a +1.5C world rather than a +1C world. But if it is barely measurable is it really going to grow to be anywhere near of the order of civilisation collapsing effects?


I agree with most of what you have said but why would you choose to draw a distinction between 1C and 1.5C. We are going to blow past 1.5C as BAU is still the rule of the day. Would be shocked if we do not find ourselves in a 3C warmer world, minimum, by the end of this century.

I think that some of our most pessimistic commenters here on this forum have this as the context from which they make their comments. Having said this, I think we are probably 2 decades from having perennial BOE's.

crandles

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Re: When will the Arctic Go Ice Free?
« Reply #555 on: July 15, 2019, 03:58:43 PM »

I agree with most of what you have said but why would you choose to draw a distinction between 1C and 1.5C. We are going to blow past 1.5C as BAU is still the rule of the day. Would be shocked if we do not find ourselves in a 3C warmer world, minimum, by the end of this century.

I think that some of our most pessimistic commenters here on this forum have this as the context from which they make their comments. Having said this, I think we are probably 2 decades from having perennial BOE's.

The 1C was about where we are now. The 1.5C was what the IPCC report was aimed at.

I agree we are likely to blow past 1.5C: Almost certainly .5C of committed warming as ocean thermal inertia takes some time to catch up with atmosphere. We haven't stopped emissions yet and that will take some time so avoiding 2C is likely to need substantial carbon drawdown tech. If that is not possible or not adequately funded we are likely to go past 2C. If renewables take off as I expect with them being cheaper only recently we may manage some slow down in the rate of rise at between +2C  and +3C. Further out than that it is hard to know what we will develop. Resilience may increase more from wealth than the increasing problems of more adverse weather.

Glen Koehler

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Re: When will the Arctic Go Ice Free?
« Reply #556 on: July 15, 2019, 06:20:00 PM »
the conclusion seems to repeatedly be that it isn't as bad as we feared.

Whichever "we" said that, they would be wrong.  Measurements and projections of both the ASI loss trajectory and impacts have shown increase over time more often than decrease.  (This also applies to climate disruption in general.)

Check out the 16 minute "A World Without Ice" author interview Neven posted the other day at the ASIB.



gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #557 on: July 15, 2019, 06:34:18 PM »
Someone posted on this thread, and totally correctly, that there has been only one year where extent was less than 4 million km2, and that was 2012. Not only that, but 2012 extent minimum was, at 3.2 million km2, more than 800,000 km2 less than 2nd place 2016 (JAXA data).

That triggered my memory of a post I think by Tealight, in which he mentioned how when looking at area, we are much closer to a BOE. Time to have a look.

2012 NSIDC Area minimum was 2.25 million km2.

Not only that, 2016 area minimum was not 800,000 km2 greater than that, it was just 200,000 km2 greater at 2.45 million km2.

Not only that, if 2019 remaining area loss is average, minimum will come in at or a bit below the 2016 figure.

Suddenly, the 2012 minimum does not look such an outlier. The reason for the difference between extent and area comparisons? Dispersion. In 2016 the not so much greater area was spread out over a far larger extent.

My (joke?) prediction for the BOE on 23rd August 2027 suddenly looks more possible, or even conservative.


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petm

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Re: When will the Arctic Go Ice Free?
« Reply #558 on: July 15, 2019, 06:51:38 PM »
Suddenly, the 2012 minimum does not look such an outlier.

Right and volume too. 2010-2012 were volume outliers for the time, but not anymore. 2016-2019 are at roughly the same level.

https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png

Ken Feldman

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Re: When will the Arctic Go Ice Free?
« Reply #559 on: July 15, 2019, 06:55:53 PM »
Quote
But they are better than nothing, you have to work with the tools you have got not the ones you would like, and the models show the same thing for 2020 2040 and 2060.

Let me be very clear about this. In the model that predicts a BOE by 2080, if you instantly remove the ice in 2020, 2040, or 2060 the ice immediately comes back. Well of course it does. The model is underestimating melt and/or overestimating freeze.

A wrong model is worse than nothing, if you make decisions according to the wrong model.

However, as the arctic keeps changing and showing scientist new secrets, I'm sure that better models will emerge.

Quote
You might want a newer source and better model, but basically tough: If it doesn't exist, then you are not going to get it. If there are two papers saying the same thing, then another paper is unlikely to be published unless it is saying something markedly different.

You don't think missing the first BOE by 4 decades (possibly more) is something markedly different?

Those model results are based on actual physics and include things often missing from the simplistic arguments about a BOE.  For example, the negative feedbacks, the depth of the central Arctic Ocean, and the fact that the gradual build up of the heat in the atmosphere mostly goes into the deep ocean, not the atmosphere or the ice.

Here's a good explanation of why there isn't expected to be a "tipping point" in the event of a BOE from a 2018 paper by Julienne Stroeve and Dirk Notz.

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta

Quote
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and Dirk Notz 2018 Environ. Res. Lett. 13 103001

Abstract
 

The decline in the floating sea ice cover in the Arctic is one of the most striking manifestations of climate change. In this review, we examine this ongoing loss of Arctic sea ice across all seasons. Our analysis is based on satellite retrievals, atmospheric reanalysis, climate-model simulations and a literature review. We find that relative to the 1981–2010 reference period, recent anomalies in spring and winter sea ice coverage have been more significant than any observed drop in summer sea ice extent (SIE) throughout the satellite period. For example, the SIE in May and November 2016 was almost four standard deviations below the reference SIE in these months. Decadal ice loss during winter months has accelerated from −2.4 %/decade from 1979 to 1999 to −3.4%/decade from 2000 onwards. We also examine regional ice loss and find that for any given region, the seasonal ice loss is larger the closer that region is to the seasonal outer edge of the ice cover. Finally, across all months, we identify a robust linear relationship between pan-Arctic SIE and total anthropogenic CO2 emissions. The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions.

Quote
4.2. Stability of the ice cover


In addition to changes in the external forcing and internal variability, a self-amplification of the ongoing ice-loss could in principle have contributed to the rapid ice loss in recent years. Such self-amplification is usually discussed in the context of so-called tipping points or nonlinear threshold, which are often defined as processes in the climate system that show substantial hysteresis in response to changed forcing.

The best known example for such possible hysteresis behavior is related to the ice-albedo feedback mechanism: a reduced ice cover in a given summer will cause increased absorption of solar radiation by the ocean, contributing to further reductions in the ice cover. Such positive feedback loop can cause the irreversible loss of Arctic sea ice in idealized studies based for example on energy-balance models (see review by North 1984), and have hence been suggested to possibly be relevant also for the real world.

However, an analysis of the existing observational record and a substantial number of respective modeling studies with complex ESMs all agree that such a 'tipping point' does not exist for the loss of Arctic summer sea ice. For example, Notz and Marotzke (2012) found a negative auto-correlation of the year-to-year changes in observed September SIE. Hence, whenever SIE was substantially reduced in a given summer, the next summer usually showed some recovery of the ice cover. This was further supported by Serreze and Stroeve (2015). Such behavior suggests that the sea-ice cover is at least currently in a stable region of the phase space, as otherwise one would then expect that any year with a really low ice coverage should be followed by a year with an even lower ice coverage, driven by the ice-albedo feedback mechanism. As shown by Tietsche et al (2011), the contrasting behavior of the real ice cover can be explained by compensating negative feedbacks that stabilize the ice cover despite the amplifying ice-albedo feedback. The most important of these stabilizing feedbacks relates to the fact that during winter the ocean very effectively releases heat from those areas that became ice free during summer, thus over-compensating for any extreme ice loss in a preceding summer. Ice that is formed later in the season also carries a thinner snow cover and can hence grow more effectively during winter (e.g., Notz 2009). Stroeve et al (2018) suggest, however, that this stabilizing feedback mechanism is becoming weaker and weaker as Arctic winters become warmer and warmer. Increased winter cloud cover after summer sea ice loss as found by Liu et al 2012 also weakens the stabilizing feedback, as it reduces the loss of heat from the ocean surface.

The apparent mismatch of observations and complex model studies on the one hand, which both show no emergent tipping-point behavior of the ice loss, and studies with idealized models, which show tipping-point behavior, was resolved in a dedicated study by Wagner and Eisenman (2015). They were able to extend simplified models until their behavior agreed with more complex models. In doing so, they found that both spatial communication through meridional heat transport and the annual cycle in solar radiation are important for stabilizing the ice cover's response to changes in the external forcing.

Rich

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Re: When will the Arctic Go Ice Free?
« Reply #560 on: July 15, 2019, 07:08:10 PM »
Someone posted on this thread, and totally correctly, that there has been only one year where extent was less than 4 million km2, and that was 2012. Not only that, but 2012 extent minimum was, at 3.2 million km2, more than 800,000 km2 less than 2nd place 2016 (JAXA data).

That triggered my memory of a post I think by Tealight, in which he mentioned how when looking at area, we are much closer to a BOE. Time to have a look.

2012 NSIDC Area minimum was 2.25 million km2.

Not only that, 2016 area minimum was not 800,000 km2 greater than that, it was just 200,000 km2 greater at 2.45 million km2.

Not only that, if 2019 remaining area loss is average, minimum will come in at or a bit below the 2016 figure.

Suddenly, the 2012 minimum does not look such an outlier. The reason for the difference between extent and area comparisons? Dispersion. In 2016 the not so much greater area was spread out over a far larger extent.

My (joke?) prediction for the BOE on 23rd August 2027 suddenly looks more possible, or even conservative.

Thanks for sharing that Gerontocrat. I learned something there.

It's kinda bizarre that the extent : area ratio would vary so much.

What caused the great dispersion of 2016?

Tor Bejnar

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Re: When will the Arctic Go Ice Free?
« Reply #561 on: July 16, 2019, 12:43:58 AM »
Thanks, Ken, for the link and long quotes.  I was curious how they dealt with Bering Sea winter lack-of-freezing in recent years.  It seems this parallels other peripheral seas, helping create this one (or several) conclusions:
Quote
5.  Accelerated sea ice loss during all months of the year is additionally driven by a lengthening of the melt season. As assessed for the Arctic as a whole through April 2018, melt onset is occurring 3 days earlier per decade, and freeze-up is happening 7 days later per decade (figure 3). Over the 40 year long satellite record, this amounts to a 12 day earlier melt onset and a 28 day later freeze-up.
Not a conclusion, but the paper includes:
Quote
while the amount of ice exported through Fram Strait has increased over the satellite data, the increased ice export might instead be linked to the fact that that a thinner ice pack is more mobile (e.g. Rampal et al 2009, Olason and Notz 2014).
A graph suggests a BOE about 2050, based on the final conclusion:
Quote
7.  The primary cause of the ongoing changes in all months are anthropogenic CO2 emissions, with a clear linear relationship between sea ice loss and cumulative anthropogenic CO2 emissions in all months (figure 7). ...
Arctic ice is healthy for children and other living things.

jdallen

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Re: When will the Arctic Go Ice Free?
« Reply #562 on: July 16, 2019, 03:07:44 AM »
I've been ruminating on this a bit...

For all of a BoE marking some sort of milestone in the Arctic, the impact of reduced summer (and Winter...) ice coverage is already making itself felt.  In short, the difference between 2 million km2 extent and 1 million km2 extent won't be that significant from the standpoint of its effect on climate.

We're already seeing dire changes to the ecosystem and major impacts to year-round atmospheric circulation.  I'm not seeing that changing much with a BoE, except on ramp up, in the manner of degree.
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binntho

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Re: When will the Arctic Go Ice Free?
« Reply #563 on: July 16, 2019, 06:33:11 AM »
Here's a good explanation of why there isn't expected to be a "tipping point" in the event of a BOE from a 2018 paper by Julienne Stroeve and Dirk Notz.

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta

Quote
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and Dirk Notz 2018 Environ. Res. Lett. 13 103001

... The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions.

With current CO2 release, an additional 800 Gt takes 50 years (36 Gt annual release, 44% of which is retained in the atmosphere).

A good article though, and I would tend to agree with the conclusions.
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Tony Mcleod

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Re: When will the Arctic Go Ice Free?
« Reply #564 on: July 16, 2019, 07:08:14 AM »
I've been ruminating on this a bit...

For all of a BoE marking some sort of milestone in the Arctic, the impact of reduced summer (and Winter...) ice coverage is already making itself felt.  In short, the difference between 2 million km2 extent and 1 million km2 extent won't be that significant from the standpoint of its effect on climate.

We're already seeing dire changes to the ecosystem and major impacts to year-round atmospheric circulation.  I'm not seeing that changing much with a BoE, except on ramp up, in the manner of degree.

You may be right, but there is another possibility and that is a flipping cold pole. Arctic-centred for now summer and winter, but starting to flicker to a Greenland centre in summer. That could be a whole lot flipping worse than a gradual ramp up.

jdallen

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Re: When will the Arctic Go Ice Free?
« Reply #565 on: July 16, 2019, 07:09:15 PM »
I've been ruminating on this a bit...

For all of a BoE marking some sort of milestone in the Arctic, the impact of reduced summer (and Winter...) ice coverage is already making itself felt.  In short, the difference between 2 million km2 extent and 1 million km2 extent won't be that significant from the standpoint of its effect on climate.

We're already seeing dire changes to the ecosystem and major impacts to year-round atmospheric circulation.  I'm not seeing that changing much with a BoE, except on ramp up, in the manner of degree.

You may be right, but there is another possibility and that is a flipping cold pole. Arctic-centred for now summer and winter, but starting to flicker to a Greenland centre in summer. That could be a whole lot flipping worse than a gradual ramp up.

I do not preclude wild cards showing which would make things even worse. In fact I kinda expect it...
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gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #566 on: July 16, 2019, 08:32:49 PM »
Here's a good explanation of why there isn't expected to be a "tipping point" in the event of a BOE from a 2018 paper by Julienne Stroeve and Dirk Notz.

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta

Quote
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and Dirk Notz 2018 Environ. Res. Lett. 13 103001

... The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions.

With current CO2 release, an additional 800 Gt takes 50 years (36 Gt annual release, 44% of which is retained in the atmosphere).

A good article though, and I would tend to agree with the conclusions.
Why agree with that methodology and not agree with this methodology?

VOLUME
Since 1980 the amount of CO2 in the atmosphere has risen by about 600GT
Summer volume minimum has decreased from about 17,000 GT to about 5,000 GT.

Thus 1 GT additional CO2 in the atmosphere equates to summer volume loss of 20GT.

To get to minimum therefore needs 5000 divided by 20 additional GT of CO2 in the atmosphere,. i.e. 250 GT.

Current rates of emissions of 36 GT and 44 % retained in the atmosphere gives 16 GT more CO2 in the atmosphere per annum.

That gives zero ice in 16 years, 2035.

Assuming 1 million km2 of area = 1,000 km3 of ice volume.
A BOE then requires volume to go down by 4,000 GT, which takes 13 years, i.e. 2032

But if volume continues on its current trend, minimum this year could be about 3,500 km3. That brings a BOE into the 2020's.

Looking that far in the future is a mug's game.
So I think the methodology I used is junk, and so is the one by Stroeve / Notz. I am amazed they came up with that. Linear extrapolations to 2050? C'mon.
« Last Edit: July 16, 2019, 08:39:07 PM by gerontocrat »
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crandles

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Re: When will the Arctic Go Ice Free?
« Reply #567 on: July 19, 2019, 05:13:18 PM »

Looking that far in the future is a mug's game.
So I think the methodology I used is junk, and so is the one by Stroeve / Notz. I am amazed they came up with that. Linear extrapolations to 2050? C'mon.

I have to agree to some extent, but:

Shouldn't use such a linear trend for such a long way into future, unless it looks reliable?

Looks quite good for a longish period: 1953 to 2017. (Or have they used scale to minimise look of y axis variation?)

My issues with it are:

Last 10 years doesn't look as good and prior to that we were losing MYI which doesn't grow back each winter, from 2012ish onward or so the ice melted is largely growing back each winter. So could be much later than the relationship suggests.

OTOH if we stop coal mining rapidly, aerosol might decline while CO2 emissions keep rising changing previous relationship. Even without such a change, the aerosol effect is short term while CO2 cumulative emissions keep rising. This may cause more rapid drop than the relationship suggests.

Maybe these have cancelling effects and the linear relationship continues. More likely there are more such effects and they are unlikely to cancel so linear relationship does not continue, but if you believe that, why so linear over 1953 to 2017 period?

crandles

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Re: When will the Arctic Go Ice Free?
« Reply #568 on: July 19, 2019, 05:49:35 PM »
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it.

Stroeve and Notz 2018
Changing state of Arctic sea ice across all seasons

Not sure it meets all your requirements or expectations though:

Quote
While it is understood that changes happening within the Arctic do not stay there, it is less certain whether current Arctic warming is already driving an increase in storm frequency and extreme weather events across the mid-latitudes, including extreme heat and rainfall events, and more severe winters. The possibility of a link has driven an increased number of studies to examine linkages in more detail. A host of mechanisms and processes have been proposed and some consensus has emerged; namely that amplified Arctic warming, regardless of its driver, has increased geopotential height thickness (Francis and Vavrus 2012, Cvijanovic et al 2017), which in turn has weakened the thermal wind (Francis and Vavrus 2012, Walsh 2014, Pedersen et al 2016). It is not clear, however, how much these atmospheric changes have influenced the jet stream (Barnes 2013) or the influence on storm tracks and occurrence of blocking events (Zhang et al 2012, Barnes et al 2014, Barnes and Screen 2015). It is entirely possible that such a link exists, yet its manifestation in the real world is likely only of minor importance given the substantial year-to-year variability arising from internal variability of the climate system.


Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #569 on: July 19, 2019, 06:24:12 PM »

Looking that far in the future is a mug's game.
So I think the methodology I used is junk, and so is the one by Stroeve / Notz. I am amazed they came up with that. Linear extrapolations to 2050? C'mon.

I have to agree to some extent, but:

Shouldn't use such a linear trend for such a long way into future, unless it looks reliable?

Looks quite good for a longish period: 1953 to 2017. (Or have they used scale to minimise look of y axis variation?)

My issues with it are:

Last 10 years doesn't look as good and prior to that we were losing MYI which doesn't grow back each winter, from 2012ish onward or so the ice melted is largely growing back each winter. So could be much later than the relationship suggests.

OTOH if we stop coal mining rapidly, aerosol might decline while CO2 emissions keep rising changing previous relationship. Even without such a change, the aerosol effect is short term while CO2 cumulative emissions keep rising. This may cause more rapid drop than the relationship suggests.

Maybe these have cancelling effects and the linear relationship continues. More likely there are more such effects and they are unlikely to cancel so linear relationship does not continue, but if you believe that, why so linear over 1953 to 2017 period?

I do not think a linear trend extrapolated that far into the future is reliable.  The slope appears to have changed several times over the decades.  A Gompertz fit, as posted by others, appears to be a better fit, but it looks to flatten the curve too much. 

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #570 on: July 19, 2019, 07:36:41 PM »
I do not think a linear trend extrapolated that far into the future is reliable.  The slope appears to have changed several times over the decades.  A Gompertz fit, as posted by others, appears to be a better fit, but it looks to flatten the curve too much.
I was taught that the gompertz or S curve is used to represent the way an event happens. A classic example is expenditure on a construction project. Costs are low at the beginning, (design, approvals etc,) accelerate in the middle as main construction takes off and slows down with fiddly finishing work at the end. We used it in doing budgets for capital expenditure programmes.
 
The curve is also usual when looking at the annual melt of the Arctic Ocean as a whole.  The melt speeds up as temperatures rise and slows down when temperatures cool down. The second reason for the gompertz curve being appropriate as a representation is that when looking at an individual sea, no matter how early it melts out, when sea ice drops below a certain amount, the percentage of the remaining sea ice lost each day remains very much the same, and therefore the absolute decrease in daily sea ice declines, creating the classic gompertz end of graph shape. But there is no reason to suppose that to be the case with immediate future years ice loss in the Arctic.

At the moment, the increase in CO2 atmospheric concentrations is accelerating. This is likely to accelerate the increase in atmospheric temperatures.
If, as expected, pollution decreases due to public opinion and decreased use of coal, this is also likely to accelerate the increase in atmospheric temperatures,. albeit temporarily.

Summer Sea ice extent minimum is still at 50 % of the 1979 value.
Winter Sea ice extent maximum is still at nearly 90 % of the 1979 value.

We are nowhere near the tail end of the event being progress to an BOE. So why should future years annual losses in Arctic sea ice decline in line with the tail end of a Gompertz curve?

The only thing that makes any sense to me is to start with the idea of what is going to happen to AGW in general and AGW in the Arctic in particular in the immediate future, i.e. the next 5 to 10 years. And that looks pretty grim to me. How you stick that into a curve is beyond me. I don't have a few cray computers to help me out, either.
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Threebellies

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Re: When will the Arctic Go Ice Free?
« Reply #571 on: July 20, 2019, 06:06:40 AM »
Gerontocrat said
Quote
Linear extrapolations to 2050? C'mon.

Every time I read many climate papers and projects I have this feeling. Concise and well said. This seems to be a very civil place bent on objective data.

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #572 on: July 20, 2019, 12:46:14 PM »
A lot of stuff on the thread about an article by Stroeve and Notz interpreted by people on the forum that the paper suggests an ice-free summer by around 2050.

Meanwhile, back in the day....

Arctic Sea Ice Extent Plummets in 2007 by BY J. STROEVE, M. SERREZE, S. DROBOT,
S. GEARHEARD, M. HOLLAND, J. MASLANIK, W. MEIER, AND T. SCAMBOS
Eos, Vol. 89, No. 2, 8 January 2008

Quote
While natural variability may instead stabilize the ice cover for the next few years, the long-term outlook is disturbing. All models evaluated in the Intergovernmental Panel on Climate Change Fourth Assessment Report show declining September sea ice from 1953 to 2006.

While these models point to a role of GHG forcing, as a group they significantly underrepresent the observed trend [Stroeve et al., 2007]. The reasons for this underrepresentation remain to be fully resolved, but overly thick ice in several of the models provides a partial explanation. Given these conservative model results, along with the remarkable events of 2007, our view is that a seasonally ice-free Arctic Ocean might be realized as early as 2030.

https://www.researchgate.net/profile/W_Meier/publication/248820158_Arctic_Sea_Ice_Extent_Plummets_in_2007/links/0deec535e81c7e2f09000000.pdf
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gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #573 on: July 20, 2019, 01:12:54 PM »
And from an earlier paper (2007)
Whither Arctic sea ice? A clear signal of decline regionally, seasonally and extending beyond the satellite record
Walter N. MEIER, Julienne STROEVE, Florence FETTERER
National Snow and Ice Data Center, University of Colorado, Boulder,

Highly edited extract follows:
________________________________________________________
Projections for ice-free conditions

Extrapolating the linear trend until the ice extent reaches zero is a naive method of projecting when ice-free conditions could occur (naive because it assumes that linear regression is always predictive, which it is not).

However, there is no reason to believe that the sea-ice trend is or will continue to be linear. Due to the sea-ice–albedo feedback, one would expect an accelerating trend, and in fact the recent acceleration in the downward trend is a tantalizing possible indication of this. Thus, two functions in addition to a linear fit have been used: a quadratic and an exponential (ex/3 was found to be a good fit).
Year range for fit       Function           First year ice-free
1953–2005               Linear               2106
                               Quadratic          2042
                               Exponential       2060

1979–2005               Linear               2101
                               Quadratic          2035
                               Exponential       2065
____________________________________________________
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A08934F159B0622754A63FEC6BDDCC2C/S026030550025444Xa.pdf/whither_arctic_sea_ice_a_clear_signal_of_decline_regionally_seasonally_and_extending_beyond_the_satellite_record.pdf
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Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #574 on: July 20, 2019, 02:09:42 PM »
Yes, the trend up to 2007 (linear or otherwise) showed a dramatic decline.  This lead to many predictions of an imminent ice-free Arctic.  Many of these were knee-jerk reactions Trends over the past decade tell a different story.  All these predictions can really tell us is that the ice is changing.  Physically, the thin ice further south was much easier to melt.  Consequently, once the Arctic started warming, melt accelerated.  The remaining ice is much closer to the pole, and will melt with greater difficulty.  The decline in multi-year ice has affected the extent of the sea ice.

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Re: When will the Arctic Go Ice Free?
« Reply #575 on: July 20, 2019, 02:26:09 PM »
Quote
, our view is that a seasonally ice-free Arctic Ocean might be realized as early as 2030.

New information causes new predictions to vary. What you are posting appear to show very little knee jerk reaction to new data and seems to me like a sign of good skill compared to wildly varying predictions on this forum. (Not sure if this is the message you are trying to convey.)

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #576 on: July 20, 2019, 02:56:43 PM »
Quote
, our view is that a seasonally ice-free Arctic Ocean might be realized as early as 2030.

New information causes new predictions to vary. What you are posting appear to show very little knee jerk reaction to new data and seems to me like a sign of good skill compared to wildly varying predictions on this forum. (Not sure if this is the message you are trying to convey.)

The knee-jerk to which is am referring is those claiming that scientists say the Arctic will be ice-free in the 2030s, when they actually say might.  Additionally, some choose the date they prefer among the many given, as in the posted data.  Yes, new predictions today, based on new information, are significantly different than those made after 2012 - some of which were knee-jerk.

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #577 on: July 20, 2019, 02:57:30 PM »
Quote
Trends over the past decade tell a different story.


Yeah, things are much worse, specially when looking at volume and how the Arctic changes are feeding on themselves and spreading all over the world.
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Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #578 on: July 20, 2019, 03:13:28 PM »
The trends over the last decades???

Anyone browsing the forum knows that things in the Arctic are getting progressively worse. The data says so itself ( unless you hide your head deep in the sand of denial and cherry pick data).

As evidenced by the spectacle in denial using poor science the risk assessment of a BOE is completely wrong.

The data clearly points are worsening conditions in the Arctic yet the "consensus" science  is expecting stabilization of the ice for 30 MORE YEARS????

Absolute madness.

Quote
New information causes new predictions to vary. What you are posting appear to show very little knee jerk reaction to new data and seems to me like a sign of good skill compared to wildly varying predictions on this forum. (Not sure if this is the message you are trying to convey.)

A BOE by 2080, without local arctic warming and without world wide consequences is horrible skill. Forcing the models to hit 2050 by hacking the algorithms is horrible skill.

Out of the horrible skill of this algorithm comes horrible risk assessment, after which comes the wrong reaction by mankind and the end of our civilization.

All because KkK can't handle scary news and scientist are ashamed to deliver them. Damnit.
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El Cid

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Re: When will the Arctic Go Ice Free?
« Reply #579 on: July 20, 2019, 05:09:52 PM »
The trends over the last decades???

Anyone browsing the forum knows that things in the Arctic are getting progressively worse. The data says so itself ( unless you hide your head deep in the sand of denial and cherry pick data).

I'll show you what anyone looking at what the data say can see.

I attach a chart which shows average volume (piomas) for the first 6 months of the given year. I use this because we already have this for 2019.
I also put in a polynomial forecast. I also attach (second chart) the 10 year rate of change which peaked 2007-12 and has been around the average of 1995-2005 in the past few years.
I also attach (third chart) the average volume for july-aug-sept-oct. As you can see, there has been really not much change since 2010.
Yes, volume is shrinking during winter. Yes, eventually we will lose all Arctic ice - no reason to argue with that. But looking at these pictures you could understand that the Center still holds and it is impossible to know how long it will, it might vanish in 2020 or hold out until 2050 - since summer volume hasn't changed for a decade, and there is a reason why: bathymetry. Our long-term models for forecasting ice clearly suck, so no surprise scientists also try to use various statistical projections (linear or any other they seem fit).
What we can see is that during the past 10 years winter volume and extent are shrinking and the surrounding oceans are warming, but still, the Center holds. Eventually the seas around the CAB will be strong(warm) enough to destroy it, but based on the data I believe it is impossible to say when it will happen.   

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #580 on: July 20, 2019, 11:22:53 PM »
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.

If you are not alarmed, you are in denial. The normal natural response of a person of science in the face of such monumental changes and uncertainty should be alarm.

If you are not alarmed you either don't really understand what is going on or fear psychology has taken over.

Members of this forum who peddle climate risk denial do not have the excuse of ignorance.
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Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #581 on: July 20, 2019, 11:29:38 PM »
Yes, there are those who refuse to acknowledge what the data states.  The summertime losses increased until the 2007-2012 maxima.  Since then losses have slowed dramatically.  Hence the graph showing a 2050 timeframe may even be too pessimistic.  Difficult to say though with any reliability.


Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #582 on: July 20, 2019, 11:40:06 PM »
This. Again.

This is a more elaborate version of the "no warming since 1998" BS.

Anyone keeping track of the Arctic can see that conditions continue to deteriorate, and the data clearly shows it. You can look at any metric, extent, area, volume, thickness, air temperatures, ocean temperatures and tell that things continue to deteriorate.

Global cooling is not expected. Global warming with Arctic amplification is in the books for the foreseeable future. Things will get even worse.

You all denying risk, and worse scientists, publishing overly conservative, thoroughly incomplete models to decision makers will be wise to pay attention to this years minimum volume and refreeze behavior. It is likely that further confirmation of hysteresis will make itself available.

I partly say this with the hope that my bad luck is such that I'm wrong about a record minimum and slow refreeze that follows.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #583 on: July 21, 2019, 01:37:59 PM »
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.

If you are not alarmed, you are in denial. The normal natural response of a person of science in the face of such monumental changes and uncertainty should be alarm.

If you are not alarmed you either don't really understand what is going on or fear psychology has taken over.

Members of this forum who peddle climate risk denial do not have the excuse of ignorance.

I have little tolerance for either alarmists or deniers, as both seem to be arguing from emotion rather than objective science.  Both will cherrypick the data to show exactly what their psyche wants, instead of looking at the bigger view.  The real kicker is that both of these extremists think that only they know the answers, and everyone else is of the opposite extreme.  Some even think that most scientists support their views, and those that do not have been corrupted by politics or the like.

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #584 on: July 21, 2019, 02:07:11 PM »
Quote
I have little tolerance for either alarmists or deniers, as both seem to be arguing from emotion rather than objective science.  Both will cherrypick the data to show exactly what their psyche wants, instead of looking at the bigger view.  The real kicker is that both of these extremists think that only they know the answers, and everyone else is of the opposite extreme.

Pssst. You are a denier and you just perfectly described yourself. You are in denial even about your denial. How do I know?

We should be alarmed BECAUSE of the uncertainties. The uncertainty surrounding climate change is already enough to bring the world to a screeching halt. If it wasn't for deniers like you speaking deliciously convenient poison it would've happened already.

It doesn't matter tho. It is a simple matter of time that you will be scared about climate change. It will only get worse and hit closer and closer to home.

Monuments should be erected for people like you, so that when SHTF and people are looking for scapegoats they know who to blame.

Sadly, people like you will likely just change tune and pretend you've been warning us about the dangers of climate change for years. People like you will turn to the scientists quoted by crandles and blame them for not crying wolf with wolves right in their faces.

Tough to be a climate scientist these days.
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dnem

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Re: When will the Arctic Go Ice Free?
« Reply #585 on: July 21, 2019, 02:21:23 PM »
Hey KK, you get my standard offer: Let's meet for lunch in 2030.  If you're not fully alarmed, lunch is on me.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #586 on: July 21, 2019, 02:22:36 PM »
Hey KK, you get my standard offer: Let's meet for lunch in 2030.  If you're not fully alarmed, lunch is on me.

Deal.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #587 on: July 21, 2019, 02:28:24 PM »
Quote
I have little tolerance for either alarmists or deniers, as both seem to be arguing from emotion rather than objective science.  Both will cherrypick the data to show exactly what their psyche wants, instead of looking at the bigger view.  The real kicker is that both of these extremists think that only they know the answers, and everyone else is of the opposite extreme.

Pssst. You are a denier and you just perfectly described yourself. You are in denial even about your denial. How do I know?

We should be alarmed BECAUSE of the uncertainties. The uncertainty surrounding climate change is already enough to bring the world to a screeching halt. If it wasn't for deniers like you speaking deliciously convenient poison it would've happened already.

It doesn't matter tho. It is a simple matter of time that you will be scared about climate change. It will only get worse and hit closer and closer to home.

Monuments should be erected for people like you, so that when SHTF and people are looking for scapegoats they know who to blame.

Sadly, people like you will likely just change tune and pretend you've been warning us about the dangers of climate change for years. People like you will turn to the scientists quoted by crandles and blame them for not crying wolf with wolves right in their faces.

Tough to be a climate scientist these days.

It is touch to be a climate scientists.  The deniers roast them for spreading false information, while the alarmists deride them for being soft on scaremongering.  Yes, there is much uncertainty.  But that is no reason to cower in fear.  Not everyone is a metathesiophobiac.

Rich

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Re: When will the Arctic Go Ice Free?
« Reply #588 on: July 21, 2019, 02:41:43 PM »
Climate change is deepening and the risks political leaders are taking is illogical from the perspective of the continuity of human civilization.

It's easy to demonstrate the deniers like Klondike are being disingenuous, but you have to choose the correct  issues.

The timing of an ice free Arctic could very well be deferred until the latter half of this century.

We can not extrapolate the experience of the shallow Arctic perimeter to the deep Central Basin.

If we treat the Central Basin as a separate entity as we should, there is no trend line supporting a likely BOE before 2030.

It may very well happen sooner than 2030, but it will be a function of weather variation.

The uncertainty that Archimid speaks to is indeed justification for rational fear. We would never get on a plane that had a 5% chance of crashing and killing us. There is no logic to support pushing the system to a point which has a meaningful possibility of causing global catastrophe.

We know enough to understand that the possibility of global catastrophe is real and too high.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #589 on: July 21, 2019, 02:47:43 PM »
Archimid, will you calling Rich a denier also, as he thinks a BOE is unlikely by 2030 also?

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #590 on: July 21, 2019, 02:51:00 PM »
Climate change is deepening and the risks political leaders are taking is illogical from the perspective of the continuity of human civilization.

It's easy to demonstrate the deniers like Klondike are being disingenuous, but you have to choose the correct  issues.

The timing of an ice free Arctic could very well be deferred until the latter half of this century.

We can not extrapolate the experience of the shallow Arctic perimeter to the deep Central Basin.

If we treat the Central Basin as a separate entity as we should, there is no trend line supporting a likely BOE before 2030.

It may very well happen sooner than 2030, but it will be a function of weather variation.

The uncertainty that Archimid speaks to is indeed justification for rational fear. We would never get on a plane that had a 5% chance of crashing and killing us. There is no logic to support pushing the system to a point which has a meaningful possibility of causing global catastrophe.

We know enough to understand that the possibility of global catastrophe is real and too high.

Disingenuous?  For posting facts, instead of rhetoric?  Or is it that I do not think the changes will bring about global catastrophe and mass extinction? 

Andre Koelewijn

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Re: When will the Arctic Go Ice Free?
« Reply #591 on: July 21, 2019, 03:33:22 PM »
The choice and arrangement of facts (or, alternatively, 'facts') are part of rhetoric, as the ancient Greek already knew.

Now, the terms 'global catastrophe' and 'mass extinction' are not really well defined terms and dependent on the context.
I've heard people argue that as long as this planet will continue to exist (at least as a dead piece of rock in space), you can't talk about a global catastrophe. On the other side of the spectrum, some disruptions in modern communication caused by e.g. sun flares could be classified as a global catastrophe.
Likewise, 'mass extinction' is a debatable term too. Of any species? Then it is a repititive process on this planet, of late rather frequent. Or is it only related to human beings? Then, does it refer only to (near-?)complete starvation of humans? Or a situation in which less than, say, 10% (of 7 billion) survives? Or a situation in which almost 10% dies? Or even "only" in a certain region?
In this forum, when it comes to 'mass extinction', I may have seen all these possibilities.

I do not want to start a discussion on definitions here, but please be a bit tolerant to what others might indicate by terms or words which you would use for quite a different situation.

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #592 on: July 21, 2019, 04:10:39 PM »
Quote
If we treat the Central Basin as a separate entity as we should, there is no trend line supporting a likely BOE before 2030.


Sorry dude, that's just what KkK loves to tells himself. The truth is different. If things continue as they have been, volume might set a new record, pulling the CAB BOE trend even earlier in time.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Shared Humanity

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Re: When will the Arctic Go Ice Free?
« Reply #593 on: July 21, 2019, 04:16:05 PM »
The trends over the last decades???

Anyone browsing the forum knows that things in the Arctic are getting progressively worse. The data says so itself ( unless you hide your head deep in the sand of denial and cherry pick data).

I'll show you what anyone looking at what the data say can see.

I attach a chart which shows average volume (piomas) for the first 6 months of the given year. I use this because we already have this for 2019.
I also put in a polynomial forecast. I also attach (second chart) the 10 year rate of change which peaked 2007-12 and has been around the average of 1995-2005 in the past few years.
I also attach (third chart) the average volume for july-aug-sept-oct. As you can see, there has been really not much change since 2010.
Yes, volume is shrinking during winter. Yes, eventually we will lose all Arctic ice - no reason to argue with that. But looking at these pictures you could understand that the Center still holds and it is impossible to know how long it will, it might vanish in 2020 or hold out until 2050 - since summer volume hasn't changed for a decade, and there is a reason why: bathymetry. Our long-term models for forecasting ice clearly suck, so no surprise scientists also try to use various statistical projections (linear or any other they seem fit).
What we can see is that during the past 10 years winter volume and extent are shrinking and the surrounding oceans are warming, but still, the Center holds. Eventually the seas around the CAB will be strong(warm) enough to destroy it, but based on the data I believe it is impossible to say when it will happen.

A worthy analysis...

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #594 on: July 21, 2019, 04:17:43 PM »
It is touch to be a climate scientists.  The deniers roast them for spreading false information, while the alarmists deride them for being soft on scaremongering.  Yes, there is much uncertainty.  But that is no reason to cower in fear.  Not everyone is a metathesiophobiac.

 "But that is no reason to cower in fear."  Certainly. That's why I keep advising you to stop cowering in fear, face the risk of climate change and take firm action against it. Wake up.
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El Cid

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Re: When will the Arctic Go Ice Free?
« Reply #595 on: July 21, 2019, 04:28:18 PM »
Ladies and gentlemen, welcome to the World Championship of Cherrypicking. Wonder why our good friend Archimid started his graph from 2000 and not 1979, the start of the data? Because that is the best fit for an intersection of the two lines before 2030. Whereas if you do this thing correctly, from the start of the data this is what you get (red: annual voulme loss in the CAB, blue: max volume in the CAB). Chart attached.


El Cid

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Re: When will the Arctic Go Ice Free?
« Reply #596 on: July 21, 2019, 04:29:29 PM »
Not that these linear extrapolations matter at all, because it is a nonlinear system, but anyway, if you claim to respects facts and data, you don't do things like this

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #597 on: July 21, 2019, 05:03:56 PM »
Actually, the regional PIOMAS data that Wipneus posts starts on the year 2000. I merely used the whole data set. Where did you get regional PIOMAS from 1979?

When using all of PIOMAS from 1979 the date of the first BOE is also around 2030, pending the result of this melting season. Image attached.

You are right that this is a non linear system. It has already gone through several state changes.

This can be clearly seen in your graph. From 1979 to 2006 CAB melting was steady. Then in 2007 a state change occur where annual volume loses increased significantly. During this time multiyear ice was destroyed. Such volume loses peaked in 2012 and since then have been climbing steadily again, towards the next step change.

See second graph for the trends after the old ice was gone in 2012.

The risk deniers argument is that in the second graph  the losses will remain steadily around the average, or even drop.

This is supposed to happen even after world warms, and Arctic amplification amplifies and the jet streams collapse and the ice albedo feedback pick up speed.  I find their argument unbelievable.

I find it much more likely that the melt will keep increasing like the "linear trend"  from 2013-2018 suggest. It is not a linear system and the forces working on the system are pushing towards warming.
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crandles

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Re: When will the Arctic Go Ice Free?
« Reply #598 on: July 21, 2019, 07:58:46 PM »
This can be clearly seen in your graph. From 1979 to 2006 CAB melting was steady. Then in 2007 a state change occur where annual volume loses increased significantly. During this time multiyear ice was destroyed. Such volume loses peaked in 2012 and since then have been climbing steadily again, towards the next step change.


You seem to be accepting this 'thick MYI destroyed' explanation which I have mentioned is in the scientific literature. But you don't seem to be thinking through the likely consequences.

> Such volume loses peaked in 2012 and since then have been climbing steadily again

What? Think about it! :

First the maximum volume line. So instead of one straight line we should have shallow decline, steep decline then shallow decline again. Fast rate being thick MYI disappearing and not coming back. Now this has gone there is more FYI which mainly reforms each winter so a shallower decline line for the maximum. This pushes the date of the intersection to later dates.

But this is not all, the shape of the maximum trend line also has consequences for the losses line. When there was a fast rate of max volume decline, this translates into more/faster open water formation and more albedo feedback so the losses increase at a faster rate. However, now that the fast rate of max volume decline has gone away, this effect also goes away and the rate of increase in losses should also be expected to be slower. (That isn't even considering whether losses decline as the ice shrinks to areas that are harder to melt)

Anyway shallower rate of decline for max volume and shallower rate of rise for the losses can give quite significantly longer times before regular ice free conditions are reached.



SteveMDFP

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Re: When will the Arctic Go Ice Free?
« Reply #599 on: July 21, 2019, 08:08:11 PM »


But this is not all, the shape of the maximum trend line also has consequences for the losses line. When there was a fast rate of max volume decline, this translates into more/faster open water formation and more albedo feedback so the losses increase at a faster rate. However, now that the fast rate of max volume decline has gone away, this effect also goes away and the rate of increase in losses should also be expected to be slower. (That isn't even considering whether losses decline as the ice shrinks to areas that are harder to melt)
 

I think the opposite is true.  Near record low minima, year after year, has meant more open water at the beginning of the arctic night, with vastly increased outgoing radiation to space in the arctic night.  Yet, the minimum has been trending down, despite this strong negative feedback.

By end of winter, there's still a (thinner) snow+ice cover over most of the traditionally ice-covered arctic, presenting a fairly typically low albedo for the spring high-insolation period.  And yet, losses have been trending to greater values, despite this negative feedback.

There's good reason to believe the observed trends will continue, as GHG levels continue to increase and sub-surface ocean warmth continues to increase.