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Messages - RoxTheGeologist

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1
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 11, 2020, 03:44:17 PM »

As we see in the Arctic, stratification prevents heat loss. Ice is an added insulator. More stratification from freshwater, colder surface waters, more ice, less heat loss and therefore warmer deep waters to melt glaciers.

2
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 10, 2020, 04:38:45 PM »

On the CO2 conversion - sadly, the amount of fuel used in a quarry generates enough CO2 to react with all the rock flour. It can be a local solution (haha). It just has to be cost-effective and fit within CARBs regulations to generate the required credits.

3
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 10, 2020, 04:35:52 PM »

At best trees store carbon, at worst they convert carbon dioxide to methane. With increased cycling of carbon and higher decay rates with increasing humidity and temperature, I would expect the latter to become more important; particularly as warm water contains less dissolved gasses.

4
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: September 09, 2020, 08:24:39 PM »
Yes, Bruce, I'm a geochemist and I've been aware for many years of the role of rock weathering and chemical buffering on global paleoclimates. Natural rock weathering is a slow process. A recent study showed that it may be practical to speed it up by using rock flour from crushed basalt as a soil amendment. This possibility has been known for a long time but the economics were not well known.

The thought is that it simply takes too much energy to crush rock in the first place. I believe total global weathering is around 0.1 GT per year, a drop in the ocean compared to the other parts of the carbon cycle.

I have a proposal on the table to work with a local construction company; they own quarries and rock flour is an issue for them. I'm looking at ways they can utilize it to soak up CO2 and produce bicarbonate and aqueous silicates.

One further complication is it's granitic, without the high number of cations one finds in more mafic rocks. The resulting absorption of CO2 is at a ratio of around 1:3. Even at $200 a ton for CO2 in California it is expensive to move the rock anywhere. A 20 ton truck costs around $500 per 100 miles.




5
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 26, 2020, 01:28:35 AM »
Is this calving unusual? It seems to have been around for a while!


6
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 05, 2020, 04:49:26 PM »

I'm in too!

7
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 10:54:59 PM »
What is the likelihood that the entire ice sheet will unfasten from the CAA and Greenland?  In the years I've been watching I don't remember seeing anything quite like this.  I did not go through every frame of every year, but it looks like it could just lift away in the not distant future.  The ice is very broken up in much of the Canadian, CAA, edge of the CAB, and it has lifted away from North Greenland. No fast ice?  The picture is today north coast of Greenland and nearby CAA.

With high winds perpendicular to the coast we can add upwelling of deeper and warmer water to the brew,

8
Arctic sea ice / Re: The 2020 melting season
« on: July 25, 2020, 06:17:40 PM »
I believe this more of a coincidence than meets the eye. In normal years the deep Beaufort is much emptier of ice, the shallower ESS often has lots of ice at this stage. And this year the deep Laptev/CAB sector is ice-free.
amsr2-uhh overlaid onto gmrt bathymetry, minimum jaxa dates, 2012-2018
must add 2019 sometime

Great post, as always.

9
Arctic sea ice / Re: The 2020 melting season
« on: July 14, 2020, 04:48:26 PM »
I have no hope for the ice in the Beaufort and the Laptev bite is already at 80N. The weather is so bad for ice that 2020 could beat 2012 without a GAC in August or September. You are right, Friv that the ECMWF forecast is brutal for the ice.

if you click this link https://clima.caltech.edu/files/2018/11/Timmermans.pdf
you will see 20 pages of images by Prof Timmermans which describe the current patterns and the build up of heat in the Chukchi and Beaufort seas. Sustained easterly winds cause upwelling that brings up some of the stored heat. The Beaufort is a death zone for late summer ice now.

And no 'recovery years' in 2021 and 2022. The GAC vented a lot of oceanic warmth.

10
Arctic sea ice / Re: The 2020 melting season
« on: July 11, 2020, 07:36:27 PM »
RE: #2478 bathymetry

Love this post blumenkraft!  Are you trying to point out the similarity in the boundary between the deep Arctic Basin and the boundary of the minimum each year, there is certainly a relationship.




There is definitely a relationship. Can be overcome, but not easy. WAA from Siberia or NAM will overcome some of it and endless compaction could do the trick on the Atlantic side.

The match-up between the ice age and the bathymetry was even more pronounced during 2016!

https://forum.arctic-sea-ice.net/index.php/topic,382.msg84085.html#msg84085


11
Arctic sea ice / Re: The 2020 melting season
« on: June 12, 2020, 05:50:24 PM »
Everything looks terrible for the ice but it has before and little melt has resulted.

I think, Armageddon's Blade is ready and possibly waited for this message. :)

earth.nullschool.net, 16.06.2020 00:00 UTC, 850 hPa.

1. A WAA near the Lena Delta. Temperature is 7.4°C. Doesn't sound outstanding. But wind speed is 90 km/h.
2. What about water vapor? 29.72 kg/m2.
3. Though it's just one point. How big is this WAA? It's everywhere.
4. Weak clouds don't provide good protection from the Sun.

Water vapour has a high enthalpy of vaporisation. That heat can melt approximately 4x it's mass of ice as it condenses. High winds blowing over warm and wet Land is an effective way of transferring heat into the ice. In this case, each 10M3 of air can melt 1M3 of ice.



12
Arctic sea ice / Re: The 2020 melting season
« on: April 20, 2020, 09:39:52 PM »

Also:

When insolation < emission, snow is bad as it insulates and prevents heat loss.
When insolation > emission, snow is good as it prevents the ice heating up.


13
Antarctica / Re: PIG has calved
« on: February 11, 2020, 07:26:06 PM »
Yes, that's what i think too.

And for how i see it, no one here thinks differently on that one.

It's going to be interesting to see if that whole 'wedge' of fractured ice clears out and we get calving along that face from both the PIG and the Ice sheet.


14
Antarctica / Re: Thwaites Glacier Discussion
« on: January 30, 2020, 10:26:27 PM »

Thanks ASLR, that makes a lot more sense now. I didn't consider the pressure changes on melting temperature.

15
Antarctica / Re: Thwaites Glacier Discussion
« on: January 30, 2020, 07:47:55 PM »
Scientists Find Record Warm Water in Antarctica, Pointing To Cause Behind Thwaites Glacier Melt
https://phys.org/news/2020-01-scientists-antarctica-glacier.html

A team of scientists has observed, for the first time, the presence of warm water at a vital point underneath a glacier in Antarctica—an alarming discovery that points to the cause behind the gradual melting of this ice shelf while also raising concerns about sea-level rise around the globe

... The recorded warm waters—more than two degrees above freezing—flow beneath the Thwaites Glacier, which is part of the Western Antarctic Ice Sheet. The discovery was made at the glacier's grounding zone—the place at which the ice transitions between resting fully on bedrock and floating on the ocean as an ice shelf and which is key to the overall rate of retreat of a glacier.

... "The fact that such warm water was just now recorded by our team along a section of Thwaites grounding zone where we have known the glacier is melting suggests that it may be undergoing an unstoppable retreat that has huge implications for global sea level rise," notes Holland, a professor at NYU's Courant Institute of Mathematical Sciences.

... Aurora Basinski, an NYU graduate student who made the turbulence measurement, said, "From our observations into the ocean cavity at the grounding zone we observed not only the presence of warm water, but also its turbulence level and thus its efficiency to melt the ice shelf base." ... "This is an important result as this is the first time turbulent dissipation measurements have been made in the critical grounding zone of the West Antarctic Ice Sheet."

https://thwaitesglacier.org/projects/melt

2°C above freezing, so that would be....? Is that 0.2°C (assuming saltwater at -1.8°C) or 2°C? The latter is scary, the former, that's not much above the melt point of the freshwater glacier. Basically an order of magnitude less energy to melt the glacier. that 10x difference may become important....

16
Science / Re: Where are we now in CO2e , which pathway are we on?
« on: January 25, 2020, 11:53:48 PM »
While writing these lines a further question came into my mind:
Is a simple addition right at all? Maybe the IR spectra of the molecules (especially CO2 and N2O) overlap and reduce each other by some interference?

The overlapping (or not) of spectra is already built into the GWP.

One think I am not sure of is if aviation emissions are counted correctly, as they are largely in the stratosphere.

17
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 15, 2020, 06:50:38 PM »
Thanks for the thread. Volume is more important than area or extant.

Well, except for aldebo and the whole Arctic amplification thing.

18
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 09, 2020, 07:07:14 PM »
I'm still wondering what has changed to increase the ice in the Barent Sea over the last year.
Perhaps the ice is more mobile. osi-saf drift sep21-jan6

Thanks for the animation! Ether more cold input or less heat or a bit of both. It could be that there is much more ice being pushed out over the Barents, that the yearly changes are just noise. We remain avid observers.

If you had to pick one visible symptom of a slowing AMOC in a warming world? For me it would be less heat in the Barents, and more ice, it's far to the North and only the AMOC's heat keeps it ice free.

19
Arctic sea ice / Re: The 2019/2020 freezing season
« on: January 08, 2020, 06:07:38 PM »
Aren't the poles the only places where the planet can lose its heat? I'm thinking that if there would be more ice, that the Arctic would be colder and able to release more heat into space, overall cooling the planet, and giving us more time before the feedback loops kick in and the climate runs out of our control.

The Arctic is heating up faster than any other place on earth, so cooling it down seems logical to me. And I don't think this would heat up the rest of the planet more.

This is entirely wrong. Hot things emit more heat than cool things. The low latitudes gain heat through insolation. The whole planet is losing heat all the time, more rapidly at the low latitudes as they are warmer. The disparity in insolation heating causes the atmosphere and oceans to operate as heat pumps, transferring heat from the low latitudes to high latitudes and increasing the overall efficiency of heat loss. If you stop the transfer of heat to the poles you reduce the ability of the earth to lose heat.

20
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: December 11, 2019, 07:25:16 PM »

Barents - will above average sea ice area continue?


Barents: I'm curious as to why we started seeing encroachment onto the Shelf. for a few years there was little ice on the shelf because of (presumably) Atlantic water effectively melting ice as it crossed the continental shelf before flowing down the slope. Why is less warm water (or more cold water) finding its way to the shelf boundary and increasing extent? Has the AMOC slowed?; Is the warm water deeper; is it finding its way around to the Nares? Should I post this on stupid questions?

21
Arctic sea ice / Re: The caa-greenland mega crack
« on: October 31, 2019, 05:32:13 PM »
Blumenkraft,

Every year in the freezing season, the volume of the Arctic sea surface expands by roughly 10 percent (due to the fact that density of sea ice is lover than that of sea water). If everything (including air pressure and sea level) remains constant, something will have to give in. . . .

I don't think that's how the physics works.  Certainly Nares and Fram surface currents are more robustly southward in winter than summer.  But not, I think, because sea water is freezing.  Sea ice displaces its *weight* and not its volume. 

Just as the water level in a glass of ice water doesn't change as the ice melts, neither does it change if ice forms in the glass.  Thus winter freezing of sea water into sea ice doesn't create any net change in forces of flow (all other changes being equal, which they never are in actuality).

I don't have an explanation for the observed seasonal flow patterns, but I'm pretty sure volume of ice formation isn't it.

If you put a piece of ice in a glass of saltwater, the freshwater from the ice flows to cover the saltwater. Freshwater/ice from the arctic is less dense and therefore there is an elevation difference. Hydrostatic stress is the same but the diviatoric stress makes the water flow (as its incompressible). its a long time since I did any continuum mechanics so my explanation may be wonky. Water flows downhill?

22
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: October 25, 2019, 06:35:24 PM »

...
But the fundamental mechanism of sea ice formation (which you seem to have forgotten here) is that sea water is densest at freezing point, which means that before any ice has time to form, the surface water starts sinking and mixing downwards, and the underlying warmer waters start to move up.

This is presumably what is happening in all the open areas of the arctic right now. Very cold air is blowing in from the south (from Siberia) and from the ice itself, but the air heats up very rapidly over the open ocean where the sea surface temperatures are above freezing.
..


Isn't the mixed layer in summer salinity stratified? Salinity has a much greater impact on density than temperature. I thought that the freshwater lens from melting ice effectively prevented any convection, maybe if the water to 10m (?) has been warmed and homogenized it will turn over as the surface cools.

Sadly we don't have enough buoy data to really get a good picture of what is happening to seas like the Chukchi, distant from rivers, and with much longer exposure to wave and current action because of the early ice loss. It might be that as the sea becomes ice free for longer, the ocean becomes homogenized to deeper levels, evaporation concentrates salt in the surface, sea ice takes longer to form and is thinner and works as a positive feedback year on year.

And no, I didn't suddenly forget the properties of salt water :) If it were freshwater, the warming and melting in the spring would cause the water column to turn over (like a temperate lake).


 

23

What? Do they not give more weight to which journals publications papers are in? That's terrifying.

Peer review is not a perfect process. A biased editor can easily send a paper to review by like minded scientists or economists, particularly as it is hard to find editors for less well respected journals.

As far as I know the IPCC is a political creation, designed to put bias onto scientific results. It gives the opportunity for a nation to weigh a paper published in EPSL as highly as one published in less renowned journals. That's particularly true when it comes to counting the cost of climate change, and exactly how to measure financial risk. Even if everyone accepts that climate change is real and anthropogenic, there is still an argument to be muddied about whether it is better to pay now or pay later.

24
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 22, 2019, 05:46:08 PM »
Quote
It is also fascinating that so little attention has been paid to this ongoing event on this forum. Nevertheless, it would appear that accumulated heat in the Arctic Ocean/system is an important factor.
Many have nothing to add and don't want to get yelled at for cluttering up the thread with their inane chatter.
Albedo, ocean heat content , decline of old ice .
Weather is the other factor.
One would suggest that weather is all that is stopping A BOE in the near term.. less than a decade.
Then it will get truly interesting.

My understanding is this: The heat lost through emission into the atmosphere is what cools the Earth. There isn't enough insolation to balance the heat loss through the year at the poles. The oceans and the Atmosphere transfer heat to the poles from the tropics where insolation is greater than the heat loss from emissions. The Arctic ocean is effectively insulated from oceanic transport by the continually refreshed halocline. The only way to create a BOE is transport of heat and water vapor by the atmosphere to north of 80 degrees, even from the surrounding peripheral seas. I'm not sure if this is what you mean by weather? If it's cold then there wont be a BOE, if it's warm and wet then there will be?



25
Snow is an insulator and a reflector. It prevents the earth losing heat and increases albedo. I foot of snow is equivalent to R15 insulation. It doesn't matter if the year was a "cold" or "warm" one, the difference is that the surface of the ground is insulated against emitting heat into space, the "ground" surface doesn't drop to -40 C or what ever the ambient temperature is. The contrast one has to consider for the analysis is the difference between winter and summer temperatures, not year on year changes.

Albedo is more important when the balance of heat loss prevented by the insulation throughout the day is less than the amount of heat added from insolation. If snow cover DOES persist into the summer then one, clearly, can make an argument that heat into the earth from insolation is going to decrease. From Shared Humanities post, the evidence is that this is not happening. Snow is melting out rapidly in the spring.

Basically we apply a nice reflective blanket in the cold of the night, to keep the heat in, then we pull it off as soon as there is enough warm sunshine to heat up the ground. My guess is its a strong positive feedback loop into warming the earth.

There will be nice deep early snowfalls from a meandering jet stream and an increasingly wet atmosphere, the latitudes that the snow will persist into spring will move north. The permafrost that relies on winter heat loss will thin and decline in extent, releasing more methane and CO2 and feeding the increasingly warm wet cycle towards an equitable climate.

The above are some of the feedbacks that amplify Milankovitch cycle variations. The cycles themselves don't change the heat input into the earth enough to cause the variations that we observe in previous interglacials. We are in a Milankovitch interglacial now and have accelerated the feedbacks by the release of gigatons of CO2.

26
Arctic sea ice / Re: The 2019/2020 freezing season
« on: October 10, 2019, 06:30:49 PM »

My opinion is this season demonstrated that there isn't enough insolation to melt the ice above 80N from a 'normal' freeze season. Too much ice is built up and it doesn't receive enough energy directly from the sun.

For that 4m km2 to melt out there has to be more heat and therefore less ice (duh!). That heat has to come from the atmosphere through the 9 months of the year that insolation isn't dominant, or from the ocean as the result of a big storm or two late in the melt season.

This part of the freeze season is critical, if the seas south of 80N are warm then there will be less Freezing Degree Days over the main pack. Increased water vapor will effect any energy transfer, such as fog over the ice edge preventing both heat loss and the vaporistation/condenstation cycle transferring a lot of energy, and perhaps from snowfall providing insulation to the ice.

It's going to be interesting to watch the next couple of months to see if the thickness of the central pack grows slowly...






27
Arctic sea ice / Re: The 2019/2020 freezing season
« on: September 27, 2019, 08:24:44 PM »

More snow = more sunlight reflected = cooling. 

Not cooling but less or later warming, that's not the same.

Cooling would happen if temps would generally be lower than before but as they are generally higher (AGW!) we have reduced/later/ warming over snow covered area than over not snow covered area.

The biggest problem with more snow is that it makes it harder for the permafrost to refreeze, and that would lead to warmer landmass during summer, and more methane in the air.

Early snow traps heat in the ground and in the ice. Instead of the surface being able to radiate heat directly to and through the atmosphere (say - 40°C) it has to conduct the heat through all those nice air pockets in the snow. On sea ice it would effectively lower the number of FDDs

Early snow = slows down heat loss (insulator)
Late snow = slows down heat gain (albedo, specific heat of melt to overcome before ice and ground heat up, insulator)

Of course and model would depend on the latitude and time of year


28
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 24, 2019, 06:32:50 PM »
When looking at the AREA graphs for the principal seas that surround the Central Arctic sea, the Laptev, ESS and Beaufort all came in well under the 2010's average.

Quite a substantial difference from the Central Arctic, the area of which is now greater than the 2010's average AND the 2000's average.

I think much of that is down to the Atlantic side of the Arctic. In the last few years before 2019 that ice age has been pushed back well over the edge of the continental slope. This year the ice remained in contact with Svalbard for the whole season. Perhaps it's correlated with the Nares strait not closing? If more Atlantic water is being diverted around Greenland that would explain less melting around Svalbard.

29
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 20, 2019, 10:53:29 PM »
Neven, are you reopening the refreezing thread today or tomorrow?  ;)

The fat lady has finally sung...

Great job Gerontocrat and Juan C. Garcia, thank you both 8) 8) You have earned a very well deserved rest now :)

Are you sure - 2018 had a big drop today, and without increases the 5 day average is still going down thanks to the century break a couple of days ago

30
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: September 20, 2019, 09:52:39 PM »

And from me too. Thank you for all the excellent data and analysis.

31
Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: September 20, 2019, 09:49:36 PM »
As kindly suggested I apply to those of you who 'get it' here: Why should there be any connection between ocean depth and surface ice. The assumption that deep water in the CAB should somehow protect the ice keeps popping up, but why should that be the case?
...
- There is a mixed layer, top 50 m. This layer is called mixed because, thanks to the action on the surface by winds, waves, etc., the mechanical input is able to mix differences in temperature and salinity by induced turbulence. It is strong enough to keep stratified layers from forming. Curiously the mixed layer has an increased salinity in most oceans except in the Arctic Ocean, which mixed layer is much fresher than at higher depths. The mixed layer ends by an abrupt salinity increase called halocline.

What makes the water of Arctic ocean mixed layer "fresh" and cold relatively? I think it's rivers, and the fact that the halocline comes before the increase of temperature, deeper under the halocline. So thanks to this strong stratification layer, the heat from beneath won't reach the mixed layer, staying relatively cold, and relatively fresh. I think there's a physical explanation for the halocline coming at lower depth than the temperature increase from deep waters, but I don't remember it. If it was not the case, there would not be Arctic ice, probably.
...
PS. Wikipedia page of the Arctic brings some interesting facts...

Thanks for that explanation. As Uniquorn points out, it is not as "idealized" as what you explain or the halocline/thermocline description in Wikipedia, but it seems THE factor: given the conditions of the Arctic Ocean, the halocline exists wherever the ocean is DEEP, inhibits mass and heat transport from the SUNK Atlantic and Pacific waters beneath, BUT the protective effect of the halocline has no room in SHALLOW shelves (peripheral seas of the Arctic proper). Temperature changes happen mostly UNDER the halocline, which helps BIG TIME the survival of the CAB in summer.

I think it is a rational explanation linking DEEP waters and SURVIVING ice.

The relationship between sea ice and bathymetry is well understood, particularly on the Atlantic side of the ocean. The warm salty waters from the Atlantic sink below the fresher Arctic waters from the Atlantic waters in under the Nansen basin. On the Pacific side the warmer Pacific waters in the Chukchi sea form the deeper waters under the Beaufort Gyre. The ice edge closely tracks the edge of the continental shelf in the summer on the Atlantic side of the Arctic.

The Freshwater cap on the Arctic is replenished by freshwater from melting ice and from the rivers, (I think about 50/50 from what I have read. The Siberian shallow seas are freshened because of the distance from the oceans and the big rivers that drain onto the shelf.

The mixed layer depth varies seasonally. In the summer it becomes shallow, there is little mixing and lots of input of freshwater causing stratification. In the winter as freezing starts the formation of ice expels dense brine that causes convection in the upper layers, and the mixed layer deepens, perhaps all the way to the halocline.

32
Arctic sea ice / Re: The 2019 melting season
« on: September 18, 2019, 06:25:46 PM »
And what is the approximate area of Arctic Ocean with depth>100m ?
That simple thought has more meat from a physics point of view than the 07 12 16 19 thing (cute signature though).
Of course the Arctic resists melting because warm water sinks at the shelves breaks. The core is not only atmospherically more protected, it does not get ocean heat at all either!
But my feeling is that a summer with a very ice-dispersive weather like 2016 will eventually melt most of it.

Although it sounds compelling, I've never really been convinced by the bathymetry argument, i.e. that deeper waters somehow protect surface ice.

The main objections I have are as follow:

1) Warm water does not sink


If the warm water is more saline it does.

33
Arctic sea ice / Re: The 2019 melting season
« on: September 17, 2019, 07:14:03 PM »
It is interesting to note that there is a pattern to the very bad years of 2007, 2012, 2016, and 2019.

The first "bad" year was 2007. It took five years for 2012 to happen. It took four years for 2016 to happen. It took three years for 2019 to happen.

Perhaps it is nonsense, but that would put 4M KM^2 minimum as "normal" come 2021 (two years after 2019, and then we are down to one year separating these instances, i.e. it becomes each and every year), with each year thereafter likely to achieve a max under 2019, 2016, and 2007.

It should also be noted the last minimum above 5M KM^2 looks to be 2009. That is potentially about 11 years between the last minimum above 5M KM^2 and the last minimum above 4M KM^2 (using the step-trend above, that year would be 2020, or it may have already occurred).

We cannot say whether the remaining decline will follow on the same gradual continuum. Below 4M KM^2, the area / volume discrepancy inherently favors massive drops in area relative to volume as 0 is approached. I would think that there will not be another 11 years between the last 4M KM^2 min and the last 3M KM^2 min.

Does that mean we are approaching an asymptote at 4 M?
Maybe temporarily but I think the volume decline means it will not hold. Maybe it is a situation of once the asymptote is breached twice consecutively it cannot recover and spirals to near 0. Until it happens two years in a row, or rather until now, there has been sufficient momentum for temporary recoveries. As we can see in the year over year charts that momentum has been fading.

I suspect the total insolation above 80°N (from observation) is too little to melt the ice that forms on a yearly basis. The ice will have to be thinner, so less FDD days or more export. That equates to warmer and wetter weather for 9 months of the year. That or some good big storms to mix the ice with the warmer water below the halocline or in the adjoining seas during the summer.

The area within 80°N is 3883031 km2 (please someone correct that math if I'm wrong!) so perhaps that is where we will asymptote, give or take a little due to land masses causing local patterns. That may persist until we build up enough imbalance between the polar and equatorial temperatures to drive additional heat into the Arctic in the form of big warm storms.



 

34
Arctic sea ice / Re: The 2019 melting season
« on: September 16, 2019, 06:37:45 PM »
JAXA/ViSHOP extent has now fallen below the 2016 minimum:

http://GreatWhiteCon.info/2019/09/the-2019-arctic-sea-ice-metric-minima/#Sep-16

Only 2012 left to beat!

That's quite a big gap. Perhaps not this season. I'm just hoping it drops another 7k so the result drops into the correct bin. By correct I mean the one I voted for.

35
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: September 15, 2019, 07:22:53 PM »

Whenever a curve or line is fitted to a graph it is to illustrate a correlation; such a correlation is the decline in sea ice volume over the last few decades. I'm no expert in sea ice modelling but, there is a fundamental need to understand how one would apply a model to be able to predict future conditions.

To understand a correlation a model is built. The model can perhaps take the starting data and then show how sea ice has changed on a year to year basis (hind casting). It can then be used to predict the future, and it's skill tested by it's ability to do so. Models are only as good as the test conditions applied. Hindcasting can be tricky as there is the temptation to model fit the data.

Obviously models based on a line fit are incorrect, they can be trivial disproved by projecting backwards in time and showing that there wasn't that much ice 10000 years ago. I hear the 'but there wasn't GHG emissions" so immediately the model has to include global warming from GHG gases. Assumptions are disproved, the model improves. If a model can effectively hind cast current sea ice from pre industrial times, then we perhaps have a chance of predicting more accurately what the future holds.

At least correlate global temperatures with sea ice volume, that seems like a better starting point than time.




36
Arctic sea ice / Re: The 2019 melting season
« on: September 12, 2019, 11:55:14 PM »

This makes a big assumption - that system behavior will be consistent as we reach that limit.

Based on the surprising end of season slowdown this year, I'm not sure that's safe. I'm still mulling hypotheses for what we are seeing and why the dynamics are not falling more in line with your assumptions. 

"Blue Ocean" is a boundary condition, and the retreat of the ice to where it stands now - post 2007 - suggests to me that the dynamics for the ice north of 80 are significantly different from those of the peripheral seas, which is were most significant visible changes in the Arctic have unfolded.


This is my thought too; that there isn't enough insolation to melt the ice N of 80°N with the current FDD thickness increase, even in a sunny year. To melt the ice there has to be less FDDs. Increased oceanic heat isn't going to effect the high Arctic sea ice while vertical mixing is prohibited by the halocline. The latter isn't likely to disappear completely because of the input of fresh water from rivers and ice melt. Mixing can occur during big storms, but they seem to be rare in the summer. If that's the case, then seeing the high Arctic ice free is likely to require a warm, cloudy winter as well as a bright summer.

Did I just state the obvious?


37
Arctic sea ice / Re: The 2019 melting season
« on: August 23, 2019, 06:49:54 PM »
At this time of the year, I'd expect calm, cloudy, and snowy weather to be the most detrimental to the longevity of ice in the Arctic. All three work to trap heat in the ocean and atmosphere.

 If the Arctic isn't losing heat as effectively then the Earth is just going to warm up faster. This melt season seems to have been particularly bad. Lots of insolation with blue skys to soak up heat, and now plenty of cloud and some snow to start trapping that heat; extra water vapor in the atmosphere from warm seas surrounding the ice providing the proverbial 'icing' on the cake. There isn't going to be a new minimum, but this is worse.

38
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: August 21, 2019, 07:35:07 PM »
Quote
Earth gravity variations will not affect anything that floats over a iso-potential surface because these variations have already been accounted for in the level variations of the iso-surface. Nothing that lies in this iso-potential surface will feel gravitational pull parallel to the iso-potential surface. BECAUSE BY DEFINITION THE GRAVITATIONAL FORCE IS PERPENTICULAR TO THIS SURFACE.
Umm the shouty bits do not make it more true.
The mass of the Greenland ice sheet is above your theoretical surface.
The ice sheet has a gravitational pull perpendicular to its mass .
When the ice is gone the gravitational effects in the local area change.
Lowering  the surface of the water nearby.
The same effect will happen in antarctic resulting  the polar sea levels falling and higher seas  the nearer you get to the equator.

http://sealevelstudy.org/sea-change-science/whats-in-a-number/attractive-ice-sheets

You are both right! SIS is correct, as are you. All things being equal water follows an equipotential surface  that is perpendicular to the gravity field. As ice melts, mass is redistributed and the shape of the surface changes, and be inference, water level. I think it's confusing as we think of things flowing up and down 'hills' but in reality, in terms of the 'hills' on the geoid, the hills are flat....

39
Arctic sea ice / Re: The 2019 melting season
« on: August 21, 2019, 07:02:32 PM »

isn't early season snow good for slowing ice loss but increases long term heat retention?

40
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: August 19, 2019, 11:23:03 PM »
Back to the problem of ice being lovely attracted to Greenland. From first principles (Newtonian):

Gravitation: a conservative force from which a potential energy field can be derived.
Ideally, water fills the oceans following a constant iso-potential surface. It will be almost horizontal, but in some places with more gravitational pull, the level will be depressed, and in others, will be higher than average.
This is a static effect. Earth gravity variations will not affect anything that floats over a iso-potential surface because these variations have already been accounted for in the level variations of the iso-surface. Nothing that lies in this iso-potential surface will feel gravitational pull parallel to the iso-potential surface. BECAUSE BY DEFINITION THE GRAVITATIONAL FORCE IS PERPENTICULAR TO THIS SURFACE. And in the case of an ice block, this is balanced by buoyancy force due to the water being denser than ice.
Same happens with earth inertial centrifugal force, proportional to the distance to the earth axis. It can be derived from a potential field, which combined, distorts a little bit the gravitational iso-potential surfaces.

Coriolis inertial force, however, is the tricky one, since this cannot be made a conservative force, it depends on the relative velocity of the ice block with respect to the Earth.

The coriolis force appears in all kinds of interesting problems of the Arctic. I would recommend to read about it rather than quantum mechanics (in the context of the Arctic). It's less attractive to discuss while smoking a joint and looking at your gin-tonic ice cubes sticking at the sides than, say, quantum mechanics paradoxes and dragons.

The geoid is a map of the equipotential surface, represented as a departure from a reference ellipsoid (the mathematical approximation for the earth). The equipotential surface includes rotational effects. It is changing slowly, from ongoing PGR and ice melt. As sis says, since it is an equipotential surface by definition gravity is always perpendicular to a tangent to the surface.

41
Arctic sea ice / Re: Freeform season chatter and light commentary
« on: August 19, 2019, 11:13:24 PM »
Oh, this should be here too...

Ups and downs from PGR

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Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 19, 2019, 11:10:01 PM »

Here's a map of the ups and downs.

43
Arctic sea ice / Re: The 2019 melting season
« on: August 19, 2019, 05:43:33 PM »
My theory is that Greenlands mass pulls the ice towards it.

I like your theory, it makes a lot of sense.

You can look at what the surface of the ocean would like like given the effects of gravity and the rotation of the earth, it's the equipotential surface - the geoid

44
Consequences / Re: Laurentide II
« on: August 13, 2019, 07:56:44 PM »

I posted a question on stupid questions noting that early and heavy snowfall is probably a good way to heat up the planet as it does a very good job of insulating against heat loss that would otherwise have been going on.

45
Arctic sea ice / Re: The 2019 melting season
« on: August 13, 2019, 06:06:22 PM »

It would be interesting to know how much ice the Barnes Ice Cap lost this yet. It seems to have been under blue sky for most of July and August.

A remnant of the last ice age. It will not survive to see the next.


Next ?


100,000 years from now

We are STILL in an ice age. What we are experiencing is the Earth's climate transitioning from a interglacial to a hothouse state. My guess is it'll take a few million years to switch back to icehouse. Go on; Prove me wrong.

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New CESM2 runs are indicating that the most likely value for ECS is 5.3C:

Oh S**t.

47
Arctic sea ice / Re: The 2019 melting season
« on: August 12, 2019, 01:37:20 AM »
I am amazed how easily the human is deceived and can "see" patterns with minimal data....

Canals on Mars.

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Arctic sea ice / Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« on: August 05, 2019, 12:43:12 AM »
Q. Can it? My response to this statement on the 2019 Melting Thread.

There is more than enough heat in the deep water to melt the ice and keep the arctic ice free year round. 

However, the heat can not move upwards through the halocline. 

The halocline is 50 meters thick (at least) and is very difficult to breach.  If it ever happens, look out!   The arctic will be a completely different place.


I've often wondered if/why the thermal conductivity of seawater is insufficient for significant melting of the ice just by thermal conduction, when the halocline is stable.

So let's see...


Consider the year-round loss of ice thickness due to thermal conduction from a 1-degree-C-warmer layer at a 50 meter depth.


ASSUMPTIONS & PROPERTIES:




CALCULATIONS:

Upwards heat flux = (temperature gradient) x (thermal conductivity) = 2e-2 K/m x 0.6W/mK = 1.2e-2 W/m^2

Thermal energy added to ice in 1 year = (Upwards heat flux) x (time in 1 year) = 1.2e-2 W/m^2  x 3.1e7 s = 3.7e5 J/m^2; multiply by 1e-4 m^2/cm^2 = 37 J/cm^2

Depth of ice melted = thermal energy added / (heat of melting x density)
= 37 J/cm^2 / (334 J/g x 0.9 g/cm^3) = 0.12 cm depth



CONCLUSIONS

So the thickness of ice melted over a year in the above scenario is only of order a millimeter.

Indeed, the thermal conductivity of seawater is insufficient to provide significant melting from deep layers of warmer, saltier water below the ice.

The layer down to the halocline is typically mixed as the ice freezes. Cold briny water is formed from expulsion, sinks and the upper layer becomes mixed.

The strong stratification in the melt season is unlikely to allow much heat to propagate by conduction. I'd expected much more heat to be transferred as ice freezes, and to stop it thickening as quickly throughout the freeze.



49
Arctic sea ice / Re: The 2019 melting season
« on: August 02, 2019, 09:05:18 PM »
My hunch is because the 2012 GAC did a lot to release heat that was entrained in deeper waters, 2013 and 2014 had less melt.

Very interesting point that I hadn't considered before.

The thin ice on the Greenland coast may also be indicative of heat building in deep waters. It's far north, and we have had plenty of Pacific to Atlantic drift this year, so why isn't it thick as usual? The only reason I can see for it being thinner is that the water is warmer! It strikes me that it's likely to be representative of the increasing heat build up in the intermediate waters. I'd say it would take a long time for extra heat to impact the surface, as it has to conduct through the halocline. If it is driven by conduction we wont be able to observe it with SST or salinity changes, so to test the theory we would have to have consistent buoy records going back a decade at least.


50
Arctic sea ice / Re: The 2019 melting season
« on: August 02, 2019, 08:35:22 PM »
I still can't make up my mind which one looks worse: 2012 or 2019, but 2019 is more fearsome.

To my eye (and most graphs), on this day 2019 looks worse. But given that the 2012 GAC was this week, it won't be for long. Unless...

My hunch is because the 2012 GAC did a lot to release heat that was entrained in deeper waters, 2013 and 2014 had less melt. 2019 looks like it is on trend, and that 'normal' conditions are getting close to 2012. I wont hold my breath for 'recovery' years in 2020 and 2021.

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