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Paul

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Is the melt season too short to produce a BOE?
« on: September 23, 2022, 02:10:25 AM »
Something that crosses my mind quite a bit as realistically the main basin melting season starts at the end of May and finishes in early September giving just 3 months to melt roughly 10 million square miles of ice to produce a BOE. So is it actually possible to melt that much ice in a reletively short time period  even in an ever warming world?

Or is it going to be something unexpected that will produce a BOE, for example true expansive open water along the CAA and Greenland leaving in effect an island of ice?

Glen Koehler

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Re: Is the melt season too short to produce a BOE?
« Reply #1 on: September 23, 2022, 03:45:09 AM »
     That pretty well sums up the Slow Transition theory that there will continue to be enough winter refreeze to exceed the amount of melt possible during the May - September melt season.  It would be interesting to compare the volume of ASI lost during a typical modern melt season with the volume of ice contained in a thin covering of ice of the Arctic Ocean.  Of course, with each year of warming, the potential melt season loss grows.  And with Atlantification and Pacific water intrusion it gets more complicated.  I suppose that the global models account for all of those factors in projecting possible BOE dates.
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El Cid

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Re: Is the melt season too short to produce a BOE?
« Reply #2 on: September 23, 2022, 07:33:30 AM »
It's my theory that there will be no BOE until the Barents and Bering (and parts of Chukchi) are ice-free all around the year reliably. These seas need to become like the N.Atlantic and if/when that happens, the "attack" on the inner Arctic will start from a better position and will be possible. If you look at ice extent in March/April, there is almost no change at all in 30 years!!! Until this is so, a BOE is hardly possible (or you need a lot of random processes happening at the same time, eg extremely strong HP and insolation during May/June, then huge storms during July and August, very strong, continuous warm air advection into the Arctic during summer, etc)

Jim Hunt

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Re: Is the melt season too short to produce a BOE?
« Reply #3 on: September 23, 2022, 09:30:58 AM »
Mind you, there is also all that stuff about there being enough heat not too far below the surface to melt all the ice several times over:

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HapHazard

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Re: Is the melt season too short to produce a BOE?
« Reply #4 on: September 23, 2022, 10:48:59 AM »
Yeah, melt from below will do it. Also I expect the basin to become more rubble-fied as time goes on, making it more mobile/easier to export towards warmer waters & vulnerable to storms.

Richard Rathbone

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Re: Is the melt season too short to produce a BOE?
« Reply #5 on: September 23, 2022, 01:15:13 PM »
Mind you, there is also all that stuff about there being enough heat not too far below the surface to melt all the ice several times over:



That only gets to melt it once, and then next winter the ice is back and the heat is gone. It requires a mechanism that releases it in a catastrophic fashion, and at the right time of year, and it still just delivers one BoE. Even if the half the Arctic burps one year and the other half the next year, no BoE and the heat is gone. Its not renewable on an annual timescale.

To get a renewable BoE takes a mechanism that stops as much ice forming in the winter, and one that doesn't depend on a one-off melt. A few more decades of GHG BAU should do it, there's just not enough CO2 up there. Yet.

Freegrass

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Re: Is the melt season too short to produce a BOE?
« Reply #6 on: September 23, 2022, 01:51:20 PM »
That only gets to melt it once, and then next winter the ice is back and the heat is gone. It requires a mechanism that releases it in a catastrophic fashion, and at the right time of year, and it still just delivers one BoE. Even if the half the Arctic burps one year and the other half the next year, no BoE and the heat is gone. Its not renewable on an annual timescale.

To get a renewable BoE takes a mechanism that stops as much ice forming in the winter, and one that doesn't depend on a one-off melt. A few more decades of GHG BAU should do it, there's just not enough CO2 up there. Yet.
When you lose stratification, and you're not making new ice anymore in winter, you don't have fresh water from the melting season anymore to restore that stratification. From then on there's only open ocean, with warm salt water that's releasing heat to the atmosphere in winter that's keeping the atmosphere too warm to make it freeze hard enough to create enough ice.

But I think that'll take many more years before that happens. We need a catastrophic August storm to mix the entire Arctic ocean for that to happen, and I don't see that happening any time soon yet.

So for the next 20 to 30 years or so, freezing season and melting season will be at equilibrium with each other, with only the weather to dictate minimums...

But that's just my humble opinion...

Edit: and what happens when the AMOC collapses in the mean time, and doesn't transport any warm water to the arctic anymore? Will the Barents sea start freezing over again if that happens?

Who knows? So keep reading the ASIF!  ;) ::)
« Last Edit: September 23, 2022, 02:12:01 PM by Freegrass »
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oren

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Re: Is the melt season too short to produce a BOE?
« Reply #7 on: September 23, 2022, 02:13:00 PM »
I think a BOE needs a combination of strong melting weather (early snowmelt, sun, warm air advection) and strong export. The export is the wildcard, much less heat is needed in the basin when a lot of ice has gone to the Barents and Greenland seas.
Due to the geography of the Arctic, export in mass can only happen in that direction, so the basic setup is a classic dipole with continental WAA.
Yes, the average melt season is too short to produce a BOE, but a crazy one could do it, in my opinion. It probably also needs that the winter volume is rather low, so back to back strong years should be part of the recipe.
As I've written elsewhere, early 2017 volume setup, with 2007 weather, could probably produce a BOE and almost certainly a strong new record.
Probability? Unknown. But I would hazard a guess of few percent per year currently, and growing with time and AGW. 5%? 10%?

Freegrass

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Re: Is the melt season too short to produce a BOE?
« Reply #8 on: September 23, 2022, 02:25:40 PM »
I think a BOE needs a combination of strong melting weather (early snowmelt, sun, warm air advection) and strong export. The export is the wildcard, much less heat is needed in the basin when a lot of ice has gone to the Barents and Greenland seas.
Due to the geography of the Arctic, export in mass can only happen in that direction, so the basic setup is a classic dipole with continental WAA.
Yes, the average melt season is too short to produce a BOE, but a crazy one could do it, in my opinion. It probably also needs that the winter volume is rather low, so back to back strong years should be part of the recipe.
As I've written elsewhere, early 2017 volume setup, with 2007 weather, could probably produce a BOE and almost certainly a strong new record.
Probability? Unknown. But I would hazard a guess of few percent per year currently, and growing with time and AGW. 5%? 10%?
If we would have had a 2012 GAC in 2020, we could have come close to our first BOE that year. But then the 2021 and 2022 cold seasons wouldn't have given us a much different outcome IMHO...
When factual science is in conflict with our beliefs or traditions, we cuddle up in our own delusional fantasy where everything starts making sense again...

Richard Rathbone

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Re: Is the melt season too short to produce a BOE?
« Reply #9 on: September 23, 2022, 04:10:09 PM »
That only gets to melt it once, and then next winter the ice is back and the heat is gone. It requires a mechanism that releases it in a catastrophic fashion, and at the right time of year, and it still just delivers one BoE. Even if the half the Arctic burps one year and the other half the next year, no BoE and the heat is gone. Its not renewable on an annual timescale.

To get a renewable BoE takes a mechanism that stops as much ice forming in the winter, and one that doesn't depend on a one-off melt. A few more decades of GHG BAU should do it, there's just not enough CO2 up there. Yet.
When you lose stratification, and you're not making new ice anymore in winter, you don't have fresh water from the melting season anymore to restore that stratification. From then on there's only open ocean, with warm salt water that's releasing heat to the atmosphere in winter that's keeping the atmosphere too warm to make it freeze hard enough to create enough ice.

But I think that'll take many more years before that happens. We need a catastrophic August storm to mix the entire Arctic ocean for that to happen, and I don't see that happening any time soon yet.

So for the next 20 to 30 years or so, freezing season and melting season will be at equilibrium with each other, with only the weather to dictate minimums...

But that's just my humble opinion...

Edit: and what happens when the AMOC collapses in the mean time, and doesn't transport any warm water to the arctic anymore? Will the Barents sea start freezing over again if that happens?

Who knows? So keep reading the ASIF!  ;) ::)

When stratification goes, there is briefly warm water everywhere, and shortly after that there is cold water everywhere, and shortly after that there is ice everywhere. Ice is what keeps the heat in.

Take the ice away with a one off event, and it comes straight back again. A covering of ice is a superb insulator. The ocean is warm because it has ice on top of it in winter. Open water in winter loses more heat than open water gains in summer. Loss of stratification has negligible effect on ocean transport of heat into the arctic, and the impact of the loss of heat from open ocean to space dominates.

Recovery mechanisms of Arctic summer sea ice
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010GL045698

Paul

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Re: Is the melt season too short to produce a BOE?
« Reply #10 on: September 23, 2022, 06:16:42 PM »
I think a BOE needs a combination of strong melting weather (early snowmelt, sun, warm air advection) and strong export. The export is the wildcard, much less heat is needed in the basin when a lot of ice has gone to the Barents and Greenland seas.
Due to the geography of the Arctic, export in mass can only happen in that direction, so the basic setup is a classic dipole with continental WAA.
Yes, the average melt season is too short to produce a BOE, but a crazy one could do it, in my opinion. It probably also needs that the winter volume is rather low, so back to back strong years should be part of the recipe.
As I've written elsewhere, early 2017 volume setup, with 2007 weather, could probably produce a BOE and almost certainly a strong new record.
Probability? Unknown. But I would hazard a guess of few percent per year currently, and growing with time and AGW. 5%? 10%?
If we would have had a 2012 GAC in 2020, we could have come close to our first BOE that year. But then the 2021 and 2022 cold seasons wouldn't have given us a much different outcome IMHO...

You see I'm not sure that would be the case, 2020's ice pack was compact(but thin) whereas 2012's ice pack was alot more diffused and the storm hit more or less in the right spot to seperate the ice pack. I still wonder if the after affects did bring some heat up beneath the ocean as ice melt was still strong afterwards.

2007's and 2020's weather patterns would be interesting against 2017's low volume but I still don't think it would be enough for a BOE.

kassy

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Re: Is the melt season too short to produce a BOE?
« Reply #11 on: September 23, 2022, 06:36:46 PM »
It is not too short according to modelling studies you just have to wait a while.

I do think a strong start with lots of export is a good start, the trick is to get early open CAB water and mix it during summer and then see how long it takes to refreeze. 
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Tom Stedman

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Re: Is the melt season too short to produce a BOE?
« Reply #12 on: September 23, 2022, 07:26:37 PM »
I recall 2020 did have a fairly sizable storm that crossed the Beaufort at the end of July.. which did leave time for most of the ice to melt there. Maybe a larger storm crossing the North Pole would have done more damage? As we are at the moment, we would need everything to go wrong to get a BOE. Temperatures rise just above zero for barely two months north of 80°. As of yet we've only got a substantial drop in extent in the CAB a small handful of times.

nadir

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Re: Is the melt season too short to produce a BOE?
« Reply #13 on: September 24, 2022, 01:56:56 AM »
No, it is not. At least not according to the models, not even the least pessimistic projections. It is a matter of how and when what is not clear. But that it will eventually happen is just physics, given our inability to react faster against climate change.

Paul

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Re: Is the melt season too short to produce a BOE?
« Reply #14 on: September 24, 2022, 01:27:41 PM »
No, it is not. At least not according to the models, not even the least pessimistic projections. It is a matter of how and when what is not clear. But that it will eventually happen is just physics, given our inability to react faster against climate change.

But that's the thing, the models are just a prediction, it's not a fact until it happens. Factors like deep waters in the CAB, lack of warming in most of the CAB(as there is always ice there) and the fact the last ice to melt is likely to be multi year ice which does not always melt at lower latitudes and closer to landmasses could mean a BOE may not happen.

Of course regardless whether it does or not, that does not mean the predictions of the consequences of climate change can't and won't happen.

wallen

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Re: Is the melt season too short to produce a BOE?
« Reply #15 on: September 24, 2022, 02:50:59 PM »
The last 2 years have produced La Ninas and a 3rd one is in the current predictions. Historically these tend to occur every 20-25 years. I think a return to the El Nino pattern will be required to see extent minimums drop below 4million sq kms and that a BOE will amongst many other factors will require 2-3 consecutive El Nino seasons.

The Walrus

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Re: Is the melt season too short to produce a BOE?
« Reply #16 on: September 24, 2022, 04:15:23 PM »
The last 2 years have produced La Ninas and a 3rd one is in the current predictions. Historically these tend to occur every 20-25 years. I think a return to the El Nino pattern will be required to see extent minimums drop below 4million sq kms and that a BOE will amongst many other factors will require 2-3 consecutive El Nino seasons.
The last time we experienced an extended La Niña was 2010-13.  We all know what happened then.

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kassy

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Re: Is the melt season too short to produce a BOE?
« Reply #17 on: September 24, 2022, 05:19:20 PM »
Quote
Factors like deep waters in the CAB, lack of warming in most of the CAB(as there is always ice there)

The deep waters are not that important (deep part isn´t frozen anyway). Getting rid of the ice cover matters which is why early opening is important which could be caused by strong melt and export start on the Atlantic side. Did not happen yet but it could happen.

When modelling the future you are looking at things that have not happened but which are likely to happen. They will be facts some day (if the models are anywhere near correct). This does not mean they are perfect. When they say 2050 i already correct that to 2040 because everything shows up quicker then we model before.

Time shall tell.
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binntho

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Re: Is the melt season too short to produce a BOE?
« Reply #18 on: September 29, 2022, 08:39:21 AM »
Last year we had a heated (!) discussion on bottom melt - to recap, some posters hotly claimed that the central Arctic only ever experienced melt from above (insolation) with no or extremely insignificant bottom melt.

Other more (or less?) temperate posters pointed to the massive melt potential of the relatively warm deep ocean layers - and that perhaps it was only a question of time until we would start to see polynia opening up in the middle of the ice pack, caused by turbulence bringing these warm waters to the surface.

In other words, exactly what seems to have happened this year - the curiously resistent pole hole, the 10.000 km2 or so of extremely low extent close to the pole and inside the ice pack itself, that seemed to persist for a couple of months in more or less the same place in spite of the pack itself shifting back and forth.

Is this a harbinger of things to come, or a one-off fluke? Was the pole hole caused by warm waters brought to the surface by turbulence, or was it just a fluke caused by a series of lows settling over the same area, one after another?

If this was indeed caused by bottom melt brought on by turbulence of some sort bringing deep waters to the surface, then something very new has entered the Arctic, something which may well force a paradigm shift in our understanding of the Arctic and the future changes of BOE.
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Re: Is the melt season too short to produce a BOE?
« Reply #19 on: September 29, 2022, 12:21:43 PM »
It was not a fluke, it was a month-long moderate storm dispersing the ice toward the periphery of the pack. This has happened before (2013).
 
After the storm in June/July, there have been others affecting the same region since this pattern has been predominant this year.

I don’t think bottom melt had anything to do with this year’s event. I am not claiming that bottom melt is zero across the CAB or even above 80N or at the Pole. In July 2020 temperatures were persistently above zero at the Pole so much so that I am confident there was great thinning from the bottom as well as from infinity of melt ponds. The pack was thin and deteriorated at the melt-pond scale (remember the vessel that reached the Pole that year and crew found very difficult to even lay foot over the ice). But the pack didn’t show big gaps visible from space because it was being compacted by the anticyclone.

Is there any direct oceanic heat influence at and near around the Pole? I don’t know, can only speak of the atmospheric influence which is apparent.

binntho

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Re: Is the melt season too short to produce a BOE?
« Reply #20 on: September 29, 2022, 01:05:25 PM »
Nadir, you make a point that others have made before you, but did not appear to convince everybody. Whether we actually saw the same phenomenon in 2013 doesn't exclude it being caused at least partially by bottom melt.

Part of the discussion, which I did not mention above, was the possibility that hypothetical oceanic heat influxes due to oceanic turbulence have been there the whole time, but with increased temperatures and thinner ice, these phenomena may suddenly become visible as polynias. Low pressure areas hovering over the same spot could be an added factor.

Is there any direct oceanic heat influence at and near around the Pole? I don’t know, can only speak of the atmospheric influence which is apparent.

Uniqorn is the specialist here, but i seem to remember him showing how the ice-free area is coincident with bathymetric features, indicating the possibility of turbulence causing heat influx. As opposed to atmospheric turbulence which is readily visible from above, oceanic turbulence is opaque and requires direct measurement which is somewhat sparse.
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Re: Is the melt season too short to produce a BOE?
« Reply #21 on: September 29, 2022, 01:51:04 PM »
can you show one sign of melt in the open hole all summer .. I looked daily and saw none and am largely in agreement with nadir that the obvious should not be discounted .
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nadir

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Re: Is the melt season too short to produce a BOE?
« Reply #22 on: September 29, 2022, 02:15:52 PM »
can you show one sign of melt in the open hole all summer .. I looked daily and saw none and am largely in agreement with nadir that the obvious should not be discounted .

I don’t say it has to be discounted. I just say we can’t observe it like we observe the weather and its effects. If NOAA deployed an array of oceanic observations in the Arctic such as that in the Equatorial Pacific (for El Niño/La Niña predictions) then we would be having a very different conversation.

Freegrass

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Re: Is the melt season too short to produce a BOE?
« Reply #23 on: September 29, 2022, 02:23:39 PM »
can you show one sign of melt in the open hole all summer .. I looked daily and saw none and am largely in agreement with nadir that the obvious should not be discounted .
I'm pretty sure it's a combination of all of the above. Storms disperse the ice. This dispersion is movement of the ice, which causes bottom melt and movement in the water column. Open water then soaks up heat from the sun, which melts more ice. And as the hole grows, it becomes more vulnerable to wind and waves that stir up the water column, which causes even more ice to melt. Etc, etc, etc...
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binntho

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Re: Is the melt season too short to produce a BOE?
« Reply #24 on: September 30, 2022, 02:27:23 PM »
can you show one sign of melt in the open hole all summer .. I looked daily and saw none and am largely in agreement with nadir that the obvious should not be discounted .

I don’t say it has to be discounted. I just say we can’t observe it like we observe the weather and its effects. If NOAA deployed an array of oceanic observations in the Arctic such as that in the Equatorial Pacific (for El Niño/La Niña predictions) then we would be having a very different conversation.

Absolutely. Any putative bottom melt caused by turbulence-induced influx of deep oceanic heat is purely speculative. But perhaps worth looking into?
because a thing is eloquently expressed it should not be taken to be as necessarily true
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