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

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21 (31.3%)
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Total Members Voted: 64

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

Author Topic: When will the Arctic Go Ice Free?  (Read 121668 times)

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Re: When will the Arctic Go Ice Free?
« Reply #250 on: March 06, 2019, 10:25:28 PM »
My initial reaction was volume is more important. I was thinking more of glaciers and the cooling effect of all that ice. Ultimately they both have advantages and disadvantages. Fundamentally they are different and both are needed to fully understand the system. In gerontocrat's post #301 in 2019 sea ice area and extent data he ruminates.

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I am still wondering how much of the recent strong extent gains and losses is from freezing / melting  and how much from existing ice being spread out or pushed together due to winds and waves.
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I think one needs to consider area and volume to better understand this system. Though area/extent and volume are related they tell you different things.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #251 on: March 06, 2019, 10:44:05 PM »
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This is largely a two-dimensional system.

Really?

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I would state that volume is the aberration here.

There is no aberration here. Area, volume and thickness are all valid variables, dependent on each other, and they all reveal different aspects of the ice. It would serve us well to completely understand how they change relative to each other and  relative to the other thousand variables out there.

Considering that the area or extent varies from 4 to 15 square km annually, while the thickness varies from 2 to 3 meters, the thickness is no more than 0.1% of each of the other two dimension.  The thickness is also an estimated value based on models, compared to the other measured values.  Physically, changes in area have a dramatically greater effect on albedo than changes in thickness.  Unless this small dimension can be shown to influence the sea ice to much greater degree than the others, I tend to ignore its effect.

The energy required to melt ice doesn't differentiate between area and volume, however, area cannot decrease until all of the thickness below the surface has been melted, therefore volume is initially more responsive to increases in energy than area. As volume declines more energy is available to both melt area, and restrict its growth (ignoring potential short term negative feedbacks from melt water).

Seems pretty straight forward to me, though, geography does matter.

While it is certainly true that the energy required does not differentiate, the amount of energy absorbed is dependent on the surface area.  Solar energy will only penetrate so far, and subsurface water only contracts one side.  Ice forms and melts in sheets, not clumps.  Remember, sea ice more closely resembles a sheet of glass, rather than an ice cube. 

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Re: When will the Arctic Go Ice Free?
« Reply #252 on: March 07, 2019, 02:12:22 AM »
This is largely a two-dimensional system,

it's about energy and how much energy is needed to melt how much ice is mostly about volume.

of course area plays a role when it comes to insolation and air-flow but nevertheless it's about how much energy is needed to melt a given amount of ice and "amount" is equivalent to volume.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #253 on: March 07, 2019, 02:15:26 AM »
This is largely a two-dimensional system,

it's about energy and how much energy is needed to melt how much ice is mostly about volume.

of course area plays a role when it comes to insolation and air-flow but nevertheless it's about how much energy is needed to melt a given amount of ice and "amount" is equivalent to volume.

And greater surface area absorbs more energy.

Juan C. García

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Re: When will the Arctic Go Ice Free?
« Reply #254 on: March 07, 2019, 03:55:20 AM »
Let’s assume that on June 1st, 2022 we will have a new record of only 9.5 million km2 of ASI extent and the weather is going to promote melting for the following 2 months, with a high pressure system all around the Arctic. Then on August, we are going to have some Great Arctic Cyclones, like the one we have on 2012.

Let’s assume two settings for June 1st, 2022:

1. On the first one, we are going to have an average ice thickness of 2.6 meters, like the one we had on 1980, with 90% of the ice being 5+ years old (yes, I know it is not going to happen  ;) ).

2. On the second setting, we are going to have an average thickness of 1.5 meters, like the one that we had on 2017. Let’s assume that 80% of the ice is 1st year old.

Well, we start with the same extent on both settings, but IMHO, at the end of August we could be having something close to a BOE in the second setting, but not on the first.

So, it is important the volume and also the quality of the ice that we have.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

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Re: When will the Arctic Go Ice Free?
« Reply #255 on: March 07, 2019, 05:03:09 AM »
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about 0.3 m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.

oren

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Re: When will the Arctic Go Ice Free?
« Reply #256 on: March 07, 2019, 06:10:43 AM »
JCG's numbers were for June, so you'd get for zero in Sept much earlier than 2068. With these assumptions it should be somewhere around 2048. But an average thickness cannot capture all the required information even for a very basic extrapolation. For that you would need the distribution of thicknesses, compared to the typical melt over the season. If 90% of the April or May ice is less thick than a season's worth of top+bottom melting, you would get a BOE as traditionally defined.

Note this is regardless of trends in extent or area, which could severely lag the drops in volume until the BOE arrives by surprise. This is because winter extent is limited by the geography of the Arctic ocean, surrounded by land on most sides, while winter thickness is dictated by freezing season temperatures. So volume is much more variable (and vulnerable) than extent/area.
High/low max extent is dictated by Okhotsk, Bering, Baffin and Barents - all are external to the Arctic Ocean and completely melt every summer. High/low max volume is sensitive to thickness in the Arctic Ocean itself. So ignoring volume is very risky.

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Re: When will the Arctic Go Ice Free?
« Reply #257 on: March 07, 2019, 06:22:15 AM »
Two points is enough to define a line but it is not nearly enough to even consider defining a trend. Maybe it wasn't intentional but that is cherry picking the data and can be used to say practically anything.  :)

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Re: When will the Arctic Go Ice Free?
« Reply #258 on: March 07, 2019, 12:53:37 PM »
This is largely a two-dimensional system,

it's about energy and how much energy is needed to melt how much ice is mostly about volume.

of course area plays a role when it comes to insolation and air-flow but nevertheless it's about how much energy is needed to melt a given amount of ice and "amount" is equivalent to volume.

And greater surface area absorbs more energy.

or reflects ;)

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Re: When will the Arctic Go Ice Free?
« Reply #259 on: March 07, 2019, 07:48:24 PM »
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about 0.3 m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
If I go back to my table and define June 1st just as a 1:1 "mixture" of May and June, we'll end up with a BOE at around 2103 (log evaluation) and 2112 (lin evaluation), which shows that there is no big difference between these two ways of evaluation, which implies an acceptable assumption of linearity. Noone of us will have the chance to prove that unless BOE happens much earlier than around the start of the next century.

[PS: The loss rate per year is around 0.03 m, not 0.3 m]

Tor Bejnar

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Re: When will the Arctic Go Ice Free?
« Reply #260 on: March 07, 2019, 09:10:57 PM »
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about [edit: 0.03] m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
I have three comments about this simplistic projection.
  • Much of the larger 1980's thickness was associated with thick multi-year ice that has drifted out The Fram (mostly) over 30+ years and has been replaced with younger ice, which in turn is replaced with about the same age of young ice, so the future decline rate is likely to be less ("Slow Transition" thread).
  • I expect Arctic ice to crumple to nothingness after it gets to 10 or 20 cm thick, due to waves, etc., so the final decline may be fast.
  • I used to have an opinion about when 'ice freedom' would occur; now I don't.
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Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #261 on: March 07, 2019, 10:17:16 PM »
Nothing in th Arctic tends to proceed in a linear fashion, and once we start to think we understand the system, it changes.  Who would have thought that the summer minimum would cease to drop over the last decade?  Many recent publications have sought to explain this.  I tend to agree that I will not live long enough to witness a BOE.

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Re: When will the Arctic Go Ice Free?
« Reply #262 on: March 07, 2019, 10:42:32 PM »
Quote
Who would have thought that the summer minimum would cease to drop over the last decade?

See the Slow Transition and many threads in this forum. Half the people here were predicting a slow down of the minimum drop before it happened. I was not one of them, but it is not true that this  slowdown was not expected by many if not most. I still think it will be faster than even the Slow transition predicts and the drops will increase soon.
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Juan C. García

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Re: When will the Arctic Go Ice Free?
« Reply #263 on: March 07, 2019, 11:19:21 PM »
Who would have thought that the summer minimum would cease to drop over the last decade?  Many recent publications have sought to explain this.  I tend to agree that I will not live long enough to witness a BOE.

There has been a "cease to drop" on extent, but not necessarily is the same on volume:

On extent, the ASI has not even able to break the 2007 record, not to mention the 2012 record. So, there are some people saying that 2012 is an outlier and even 2007 will be difficult to break. But I don’t like extent! Yes, it is important to measure the effect of the Arctic Ocean albedo. But to measure the ASI drop, I am convinced that we should use volume, even if it is harder to measure than extent.

So, what do I see on volume?

First, volume on 2007 has been broken several times. On volume, [September] 2007 is the ninth lowest on record! And even that September 2012 is still the lowest, the difference between 2012 with 2010-2011 and 2016-17 is not that big.

The 39.5% ice that we have on 2010-18, versus the 1979-2000 baseline, is climate change, not just one year, not weather change.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

jai mitchell

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Re: When will the Arctic Go Ice Free?
« Reply #264 on: March 08, 2019, 02:19:15 AM »
h/t to AbruptSLR for pulling this one out.  It shows how the Arctic is being cooled by2.4 to 5.5 (median estimate 3.0) Celsius from aerosols

Title: "Arctic Clouds Highly Sensitive to Air Pollution"

https://eos.org/scientific-press/arctic-clouds-highly-sensitive-to-air-pollution


Q. Coopman et al. (09 November 2017), "High Sensitivity of Arctic Liquid Clouds to Long‐Range Anthropogenic Aerosol Transport", Geophysical Research Letters, https://doi.org/10.1002/2017GL075795

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL075795


Abstract

The rate of warming in the Arctic depends upon the response of low‐level microphysical and radiative cloud properties to aerosols advected from distant anthropogenic and biomass‐burning sources. Cloud droplet cross‐section density increases with higher concentrations of cloud condensation nuclei, leading to an increase of cloud droplet absorption and scattering radiative cross sections. The challenge of assessing the magnitude of the effect has been decoupling the aerosol impacts on clouds from how clouds change solely due to natural meteorological variability. Here we address this issue with large, multi‐year satellite, meteorological, and tracer transport model data sets to show that the response of low‐level clouds in the Arctic to anthropogenic aerosols lies close to a theoretical maximum and is between 2 and 8 times higher than has been observed elsewhere. However, a previously described response of arctic clouds to biomass‐burning plumes appears to be overstated because the interactions are rare and modification of cloud radiative properties appears better explained by coincident changes in temperature, humidity, and atmospheric stability.

image below from a different study that (apparently) underestimated the arctic cooling from aerosols.
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Dharma Rupa

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Re: When will the Arctic Go Ice Free?
« Reply #265 on: March 09, 2019, 03:15:45 PM »
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about [edit: 0.03] m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
I have three comments about this simplistic projection.
  • Much of the larger 1980's thickness was associated with thick multi-year ice that has drifted out The Fram (mostly) over 30+ years and has been replaced with younger ice, which in turn is replaced with about the same age of young ice, so the future decline rate is likely to be less ("Slow Transition" thread).
  • I expect Arctic ice to crumple to nothingness after it gets to 10 or 20 cm thick, due to waves, etc., so the final decline may be fast.
  • I used to have an opinion about when 'ice freedom' would occur; now I don't.

I've no idea on point 1, but I agree totally with points 2 and 3.  It's very unclear when the BOE will happen, but when it does the end will come suddenly.

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Re: When will the Arctic Go Ice Free?
« Reply #266 on: March 09, 2019, 10:17:55 PM »
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about [edit: 0.03] m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
I have three comments about this simplistic projection.
  • Much of the larger 1980's thickness was associated with thick multi-year ice that has drifted out The Fram (mostly) over 30+ years and has been replaced with younger ice, which in turn is replaced with about the same age of young ice, so the future decline rate is likely to be less ("Slow Transition" thread).
  • I expect Arctic ice to crumple to nothingness after it gets to 10 or 20 cm thick, due to waves, etc., so the final decline may be fast.
  • I used to have an opinion about when 'ice freedom' would occur; now I don't.

I've no idea on point 1, but I agree totally with points 2 and 3.  It's very unclear when the BOE will happen, but when it does the end will come suddenly.
Speaking to point 2 I think volume will be the driver. I think the I think the tip over point will occur at somewhere around 2000KM3 volume. When the Arctic ice reaches that threshold I think the other mechanical forces we are thinking about will come into play and will overwhelm the remaining extent very quickly.
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crandles

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Re: When will the Arctic Go Ice Free?
« Reply #267 on: March 09, 2019, 10:56:32 PM »
Is there any reason for thinking that a lot of area will suddenly go below some critical threshold whether between 10 and 20cm or some other particular thickness?

Why aren't people considering the ice to be more like a wedge as the minimum is approached with the thickest parts nearest Greenland/CAA? And there are, in any year, always some bits going below that critical thickness?

Is it just because that doesn't fit with personal beliefs that when the end comes it will happen suddenly? Can you see how this sounds like, I want this fast end collapse conclusion and therefore I am going to believe in this sudden collapse once it goes under a certain threshold rather than working with what we would expect to ultimately arrive at a conclusion?

If you have worked it the other way, considered the wedge as explained above and have reasons for dismissing it, then that is fine, you will be able to explain your reasoning as to why you reached that conclusion and won't find this post annoying. If you just find this post annoying then ....

wdmn

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Re: When will the Arctic Go Ice Free?
« Reply #268 on: March 09, 2019, 11:44:30 PM »
@Crandles,

I think the wedge point is a fair one, but all it does it is reaffirm the argument for why volume is more important than extent. Not just average volume though, since location matters.

That said, there's a clear reason for seeing how extent can lag behind volume, just by comparing the shape of the decline for both volume and extent.

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #269 on: March 10, 2019, 12:35:14 AM »
Quote
Why aren't people considering the ice to be more like a wedge as the minimum is approached with the thickest parts nearest Greenland/CAA? And there are, in any year, always some bits going below that critical thickness?

Reviving an old A-Team image. This is what extent hides:



The images above are the September minimum with ice <1.5m removed from 1978-2016. 

The thick ice is not just melting, it is being exported through the garlic press and fram (Now replaced by the kill zone north of Svalbard). That thick ice is barely being replaced.

Quote
Is there any reason for thinking that a lot of area will suddenly go below some critical threshold whether between 10 and 20cm or some other particular thickness?

Thinner ice melts faster, but usually by the time most of the thin ice is gone is August or September and the sun works in our favor. A weak freezing season with a low max volume ( like 2017, 20.782 maximum volume) coupled with a strong melting season (like 2012, 19,692 volume loss) is already enough to get us to an ice free state (20.782-19,692= 1,091, virtually ice free). No threshold needed, only bad climate luck.

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Is it just because that doesn't fit with personal beliefs that when the end comes it will happen suddenly?

In my case is because nature likes abrupt change. Systems are stable until they are sufficiently modified and then they can change to completely different states. The Arctic seems an awful lot like the kind of system that will abruptly change once sufficiently disturbed, the same for the atmospheric and oceanic currents affected by the presence of ice.

Quote
Can you see how this sounds like, I want this fast end collapse conclusion and therefore I am going to believe in this sudden collapse once it goes under a certain threshold rather than working with what we would expect to ultimately arrive at a conclusion?

Can you see the other way tho? Can you acknowledge the implication of a fast Arctic collapse on the world that we live? Can you acknowledge how difficult it would be for scientists to claim that the world might end in just a few decades? They can't. If they do they will be called crazy. Are you familiar with double blind experiments? DO you know why they do it? Do you realize that climate science there is no double blind experimentation because the science directly affects the scientist?
« Last Edit: March 10, 2019, 02:51:42 AM by Archimid »
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Re: When will the Arctic Go Ice Free?
« Reply #270 on: March 10, 2019, 01:55:17 AM »
Is there any reason for thinking that a lot of area will suddenly go below some critical threshold whether between 10 and 20cm or some other particular thickness?

Why aren't people considering the ice to be more like a wedge as the minimum is approached with the thickest parts nearest Greenland/CAA? And there are, in any year, always some bits going below that critical thickness?

Is it just because that doesn't fit with personal beliefs that when the end comes it will happen suddenly? Can you see how this sounds like, I want this fast end collapse conclusion and therefore I am going to believe in this sudden collapse once it goes under a certain threshold rather than working with what we would expect to ultimately arrive at a conclusion?

If you have worked it the other way, considered the wedge as explained above and have reasons for dismissing it, then that is fine, you will be able to explain your reasoning as to why you reached that conclusion and won't find this post annoying. If you just find this post annoying then ....
I don't *want* a fast collapse conclusion, Crandles.  My understanding of the system dynamics tends to support that kind of event.

I'm not denying that thicker ice will still make up a significant portion of that volume; in fact I expect it - exactly from some of the sources like Greenland that you're thinking of.

However comparatively that ice will make up a comparatively small extent and area - likely under  the 1 million KM2 metric a lot of people are thinking of.

That ice *will* be durable and will be around for centuries, but it won't be near enough to prevent the massive changes in system dynamics that will take place once we start loosing most of the CAB extent.  That's what I'm thinking about when I talk about a tip over point.
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Re: When will the Arctic Go Ice Free?
« Reply #271 on: March 10, 2019, 02:05:52 AM »
I recall a 'flash melting' due to a GAC (great Arctic Cyclone).  I expect more in the future.  Yes, there will be thicker ice that won't flash disappear, until there isn't.  As I don't have any of that 'magical' Chinese elixir, I may well not see that day.
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Re: When will the Arctic Go Ice Free?
« Reply #272 on: March 10, 2019, 10:09:50 AM »
Yes, I recall two GACs. 2016 showed 2012 was not a fluke, especially when looking at high-resolution metrics such as AMSR2 area, and the state of the ice around the Pole.
I expect the first BOE season to also have a GAC, which provides an extra punch right there at the end, when the sun is weak but the water is relatively warm and the surviving ice quite vulnerable.

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Re: When will the Arctic Go Ice Free?
« Reply #273 on: March 12, 2019, 03:00:25 PM »
Discussions of fast crashes when thickness gets below a given threshold always strike me as conflating two UTTERLY different things.

The first is the kinetics of how the thickness of a given piece of ice melts during the course of a season.  As it gets thinner, eventually there comes to be a point where it's too thin to maintain structural integrity, fragments and rapidly melts.

The second is the kinetics of how the average statistical distribution of ice thickness changes from year to year.

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Re: When will the Arctic Go Ice Free?
« Reply #274 on: March 13, 2019, 06:25:43 AM »
Discussions of fast crashes when thickness gets below a given threshold always strike me as conflating two UTTERLY different things.
<snippage>
(summarized: melting behavior and distribution)
Good point.

Between the two of them, I think volume is the unifying factor, rather than either one of those on its own.
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Re: When will the Arctic Go Ice Free?
« Reply #275 on: March 13, 2019, 09:34:45 AM »
I think using generalized volume is a simplification because the periphery and the central arctic behaves quite differently (probably due to bathymetry). Attached is the volume for the CAB only.

It seems to me that we currently have a new "balance" in the CAB (circled) which will probably last until Atlantic warm water intrudes and finally mixes well and then the CAB will be gone. I think it is impossible to know when this will happen  and linear/polynomial, etc. projections are not useful

uniquorn

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Re: When will the Arctic Go Ice Free?
« Reply #276 on: March 13, 2019, 10:32:43 AM »
Attached is the volume for the CAB only. <snippage>
Nice chart, are they piomas numbers?
This may not be a 'balance' but a temporary pause while MYI and 2 year ice is flushed out.

oren

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Re: When will the Arctic Go Ice Free?
« Reply #277 on: March 13, 2019, 11:04:32 AM »
Nice chart indeed.
The fact that a new lower max was set in early 2017 hints that the process is not really over, so I am not sure this is a balance. But certainly the CAB will be more resilient, with its consistent winter freezing and short melting season.

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Re: When will the Arctic Go Ice Free?
« Reply #278 on: March 13, 2019, 12:06:30 PM »
Missed the vote...by 6 months...lol.
Seeing 12 members voted for this season tells me alarm is alive and well. Sorry, don't see it in the data at all. Decent volume, extent not too bad...better than last few years. Maybe in 50-100 years. About the same time frame it will logical and feasibly take to make the complete switch...or nearly so...to renewable energy

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Re: When will the Arctic Go Ice Free?
« Reply #279 on: March 13, 2019, 12:48:47 PM »
Attached is the volume for the CAB only. <snippage>
Nice chart, are they piomas numbers?

Yes, piomas data from Wipneus' page.

I think increased ocean heat is nibbling at the CAB and eventually this will lead to a collapse. Could happen next year or in 2050 for all we know.

Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #280 on: March 13, 2019, 02:46:48 PM »
Nice chart indeed.
The fact that a new lower max was set in early 2017 hints that the process is not really over, so I am not sure this is a balance. But certainly the CAB will be more resilient, with its consistent winter freezing and short melting season.

Except that poimas volume has returned to the previous years.  I agree with El Cid (thank you for the chart, by the way), and that we are in a new balance, and impossible to say how long it will last.

Gray-Wolf

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Re: When will the Arctic Go Ice Free?
« Reply #281 on: March 13, 2019, 04:42:19 PM »
Sorry, don't see it in the data at all.

said most cryosphere scientists in Sept 2007!

I know we focus in on the Basin but there is a big old world beyond that and since the Pacific naturals flip in 2014 I believe we are seeing the rates of warming increase up and beyond that seen through the 80's/90's?

The Super Nino might have messed with the new patterns settling in but the past year has seen them look much more settled?

If the record heat from the South of the planet merely passes across the equator with the sun around the 21st then we could be in for a heck of a summer what with Yamal ready to go pop and the sea ice ground down into ever smaller individual floes glued together by younger ice and with us also in the return period for the 'perfect melt storm'............ plenty of potential for an " Oh! Shite!" moment!

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El Cid

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Re: When will the Arctic Go Ice Free?
« Reply #282 on: March 13, 2019, 05:03:37 PM »
Sorry, don't see it in the data at all.


I know we focus in on the Basin but there is a big old world beyond that and since the Pacific naturals flip in 2014 I believe we are seeing the rates of warming increase up and beyond that seen through the 80's/90's?

The Pacific might have "flipped" in 2014. I attach a picture of 2014-18  winter temp anomaly vs 2000-2010.

It is obvious that the Bering region warmed up very much and sucked in warm air from the south - probably creating string ridging and an anomalously cold Hudson region as the cold was "pushed out" into that region. The same thing happened in 2019 (not on pic), so we could call it a trend.
The consequence (other than bitter winter cold intrusions for NA) is probably a weak Bering/Chukchi which could dissipate fast come summer. Will that be enough to break the new CAB volume "balance"? I do not know.

oren

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Re: When will the Arctic Go Ice Free?
« Reply #283 on: March 29, 2019, 10:58:28 AM »
https://cryospherecomputing.tk/IceFreeDays
Parts of the arctic have already gone partially ice-free. Here is an image from a new visualization tool by Tealight (a.k.a Nico Sun) showing the anomaly of ice-free days in 2017 compared to the long term average. You can clearly see the two-pronged advance of the Atlantic and the Pacific into the Arctic.
One doesn't need a blue ocean event to have far-reaching consequences.


Note: Bear in mind the anomaly is limited by the number of ice-covered days each pixel had to begin with.

Aluminium

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Re: When will the Arctic Go Ice Free?
« Reply #284 on: April 02, 2019, 10:27:49 AM »
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).


kassy

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Re: When will the Arctic Go Ice Free?
« Reply #285 on: April 02, 2019, 01:15:14 PM »
The Transpolar Drift is faltering -- sea ice is now melting before it can leave the nursery


The dramatic loss of ice in the Arctic is influencing sea-ice transport across the Arctic Ocean. As experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research report in a new study, today only 20 percent of the sea ice that forms in the shallow Russian marginal seas of the Arctic Ocean actually reaches the Central Arctic, where it joins the Transpolar Drift; the remaining 80 percent of the young ice melts before it has a chance to leave its 'nursery'. Before 2000, that number was only 50 percent. According to the researchers, this development not only takes us one step closer to an ice-free summer in the Arctic; as the sea ice dwindles, the Arctic Ocean stands to lose an important means of transporting nutrients, algae and sediments. The new study will be released as a freely accessible Open Access article in the online journal Scientific Reports on 2 April 2019.

...

"Our study shows extreme changes in the Arctic: the melting of sea ice in the Kara Sea, Laptev Sea and East Siberian Sea is now so rapid and widespread that we're seeing a lasting reduction in the amount of new ice for the Transpolar Drift. Now, most of the ice that still reaches the Fram Strait isn't formed in the marginal seas, but comes from the Central Arctic. What we're witnessing is a major transport current faltering, which is bringing the world one major step closer to a sea-ice-free summer in the Arctic," says first author Dr Thomas Krumpen, a sea-ice physicist at the Alfred Wegener Institute.

This trend has been confirmed by the outcomes of sea-ice thickness measurements taken in the Fram Strait, which the AWI sea-ice physicists gather on a regular basis. "The ice now leaving the Arctic through the Fram Strait is, on average, 30 percent thinner than it was 15 years ago. The reasons: on the one hand, rising winter temperatures in the Arctic and a melting season that now begins much earlier; on the other, this ice is no longer formed in the shelf seas, but much farther north. As a result, it has far less time to drift through the Arctic and grow into thicker pack ice," Thomas Krumpen explains.

...

https://www.brightsurf.com/news/article/040219479881/the-transpolar-drift-is-faltering-sea-ice-is-now-melting-before-it-can-leave-the-nursery.html
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Klondike Kat

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Re: When will the Arctic Go Ice Free?
« Reply #286 on: April 02, 2019, 02:17:17 PM »
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).

Using linear regression for predictions in a non-linear system may not be the best.  Hence, I think you have over-estimated the probabilities.

oren

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Re: When will the Arctic Go Ice Free?
« Reply #287 on: April 02, 2019, 02:46:05 PM »
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).

Using linear regression for predictions in a non-linear system may not be the best.  Hence, I think you have over-estimated the probabilities.
Or under-estimated.
I think the odds of 2019 producing a minimum below 2012 are much higher than the ~7% (1:14) shown in the graph. Probably double that at 1:7. OTOH I think the odds for 2020, 2021, 2022... are not materially different, unlike the trend shown in the graph.
In essence I think the linear ice loss trend is less reliable for predictions, but that there is much greater volatility enabling any given year to set a new record minimum, with a little cooperation from the weather and maybe an August GAC. The dice are heavily loaded.

Aluminium

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Re: When will the Arctic Go Ice Free?
« Reply #288 on: April 02, 2019, 02:59:31 PM »
It was not about ice free Arctic. Results for minimum under 106 km2 see below.

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Re: When will the Arctic Go Ice Free?
« Reply #289 on: April 02, 2019, 05:45:33 PM »
Some years before a BOE becomes anything like normal, will we have to change the maps vis a vis where the Atlantic ends and the Arctic begins?

I can see an International Conference looming by about 2030 (or before?) ?
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Stephan

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Re: When will the Arctic Go Ice Free?
« Reply #290 on: April 02, 2019, 06:40:53 PM »
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).
From linear regression of the Sep averages an area of 3,50 M km² will be reached around 2030.

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Re: When will the Arctic Go Ice Free?
« Reply #291 on: April 02, 2019, 07:53:30 PM »
Some years before a BOE becomes anything like normal, will we have to change the maps vis a vis where the Atlantic ends and the Arctic begins?

I can see an International Conference looming by about 2030 (or before?) ?

Russia's about to get a NATO invite in the mail

gerontocrat

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Re: When will the Arctic Go Ice Free?
« Reply #292 on: April 02, 2019, 08:03:04 PM »
I was thinking more along the lines of that when a sea is more or less ice-free (say less than 10% area) for more than 6 months of the year, its nature is more of an open water sea than an Arctic Sea.

Then I might argue that this is Atlantification beyond the point of no return, and is more a part of the Atlantic Ocean than the Arctic Ocean.

As the graph attached shows, on the Atlantic Front the Barents Sea is on the point of no return of Atlantification, the ice-free days (less than 10 % area) increasing from about 100 days in the 1980's to around 200 days now.

Tealight and his alter ego Nico Sun shows the same thing graphically.

The opportunities for argument about defining an open water sea are no doubt tending to the infinite. "But this is my definition that belongs to me"
« Last Edit: April 02, 2019, 08:15:47 PM by gerontocrat »
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Stephan

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Re: When will the Arctic Go Ice Free?
« Reply #293 on: April 07, 2019, 10:10:41 PM »
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. March value now includes 2019.
As extent, volume and thickness in March 2019 lie all above the long-term linear trend lines it is clear that the BOE for March will take place a few years later than calculated last March. All slopes decreased slightly, and March has, together with April, the smallest slope.

Please note that this is not a forecast but a trend!
See attached table.

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #294 on: May 05, 2019, 03:23:51 PM »
It seems maximum volume was reached in day 110. I will update the model that belongs to me for when the Arctic will go ice free every tic. That is, for every minimum and maximum volume I will update the trendlines and averages and combine them into an animation.

I will do one assuming the minimum hit a new state in 2007 and another one using the whole satellite data set. Let me know what you think.
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jdallen

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Re: When will the Arctic Go Ice Free?
« Reply #295 on: May 06, 2019, 08:57:09 AM »
It seems maximum volume was reached in day 110. I will update the model that belongs to me for when the Arctic will go ice free every tic. That is, for every minimum and maximum volume I will update the trendlines and averages and combine them into an animation.

I will do one assuming the minimum hit a new state in 2007 and another one using the whole satellite data set. Let me know what you think.
The bottom trendline bothers me, for a specific reason; it's a proxy for the annual heat entering the Arctic.

That isn't decreasing, *can't* decrease past a hard limit described by that total insolation + other heat inflows.

I'd be highly surprised if it really could drop below 17,000km3/year.  I doubt it can remain consistently below 18,000km3/year.

That's the value I'm actually watching to determine when we hit "ice free".
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El Cid

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Re: When will the Arctic Go Ice Free?
« Reply #296 on: May 06, 2019, 10:20:57 AM »
Nice charts Archimid!

2030ish seems believable.

Although, who knows? Could happen even this year for all we know

crandles

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Re: When will the Arctic Go Ice Free?
« Reply #297 on: May 06, 2019, 01:30:10 PM »

The bottom trendline bothers me, for a specific reason; it's a proxy for the annual heat entering the Arctic.

That isn't decreasing, *can't* decrease past a hard limit described by that total insolation + other heat inflows.

I'd be highly surprised if it really could drop below 17,000km3/year.  I doubt it can remain consistently below 18,000km3/year.

That's the value I'm actually watching to determine when we hit "ice free".

>"*can't* decrease past a hard limit"

Alternatively, you could (more correctly?) argue it *can't* be above max volume.

Anyway there appears an issue with your version: If the ice gathers heat from the same area then "total insolation + other heat inflows" will not go down seems sensible. However if the ice shrinks to a smaller area then isn't it logical that the heat energy that the ice can gather from "total insolation + other heat inflows" is also likely to go down?

Same area but thinner and the energy gathered by the ice is likely to go up not stay steady or go down. We have had a lot of this as thick MYI disappeared. (~2000-2012?) We have reached the end of this rapid thinning and now we are getting more of the area shrinkage with volume.

So is a horizontal or straight line extrapolation appropriate?

Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #298 on: May 06, 2019, 02:16:31 PM »
The bottom trendline bothers me, for a specific reason; it's a proxy for the annual heat entering the Arctic.

That's how I like to look at it.

Quote
That isn't decreasing, *can't* decrease past a hard limit described by that total insolation + other heat inflows.

I suppose that the hard limit is the minimum value for loss in the satellite set. That value is 13.9 and happened in 1996. The graph starts at 14. So all the values that have been proven possible are present in the graph

Quote
I'd be highly surprised if it really could drop below 17,000km3/year.  I doubt it can remain consistently below 18,000km3/year.

I think clouds are the only thing that can possibly bring the value down to lower levels, but so far they haven't.

Quote
That's the value I'm actually watching to determine when we hit "ice free".

I think we will have a record loss year soon, even if the ice is harder to melt because of geometry or clouds. Next strong El Niño year will likely be the first BOE.
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Archimid

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Re: When will the Arctic Go Ice Free?
« Reply #299 on: May 06, 2019, 03:19:20 PM »
Alternatively, you could (more correctly?) argue it *can't* be above max volume.

It can't go above max volume in terms of water volume. In term of heat it can certainly go past max negative heat.

Quote
However, if the ice shrinks to a smaller area then isn't it logical that the heat energy that the ice can gather from "total insolation + other heat inflows" is also likely to go down?

It is not just likely. Direct "total insolation" will go down with area as sure as the Earth is round.  The question is, will it go down enough to offset the increase in "other heat inflows"?

Quote
Same area but thinner and the energy gathered by the ice is likely to go up not stay steady or go down. We have had a lot of this as thick MYI disappeared. (~2000-2012?) We have reached the end of this rapid thinning and now we are getting more of the area shrinkage with volume.

The graph showing losses for 2007-2018 already takes that mechanical feature of Arctic melt somewhat into account as it doesn't include the years when ice was significantly thicker. Even so, losses are greater now that the ice is thin than when the ice was thick.



Quote
So is a horizontal or straight line extrapolation appropriate?

For the Maximum volume a linear extrapolation works very well. For the minimum it doesn't. That's why I include two versions. One takes the satellite data set as the Arctic system, the other assumes there was a state change in 2007 and data before that is meaningless. Hopefully, we get to see how they change over time.

A less technical answer would be that  linear extrapolation is what it is. It assumes that exactly what happened in the past will happen in the future. It is naive because it is a fact of life that things change. But it is insightful because it is also a fact of life that things tend to repeat.

I am an energy reservoir seemingly intent on lowering entropy for self preservation.