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Messages - RoxTheGeologist

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1
Arctic sea ice / Re: MOSAiC news
« on: April 12, 2021, 05:30:40 PM »

Uniquorn - that is a wonderful graphic. Wow.

On the buoy temperature profile - there isn't the same amplitude of noise in the 10 and 20m traces compared to the 20,50 and 100m. Is there an explanation besides lack of mixing?


2
Antarctica / Re: Pine Island Glacier (PIG) Calving and Discussion
« on: April 01, 2021, 08:19:54 PM »
A recent research paper for the technical guys

https://tc.copernicus.org/articles/15/1501/2021/tc-15-1501-2021.pdf

... To this end we show that early warning indicators in model simulations robustly detect the onset of the marine ice sheet instability


Honestly, from the brilliant animations from everyone on this thread, I think we have all seen this happen blow-by-blow, the glacier accelerating and thinning, the switch from a ductile to brittle rheology on the margins causing the margins to lose cohesion; the subsequent start of the break up of the NIS and SIS. The latter is worrying: It seems to be happening very rapidly. We might find out if Pollard was right back in 2015 sooner than we all hope.

3
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: March 19, 2021, 02:44:02 AM »
The latest EIA report on oil demand makes worrying reading. No paywall

https://webstore.iea.org/download/direct/4329

"However, current government policies and industry plans show that
energy transition initiatives will have only a marginal impact on oil
demand over the next six years. This report forecasts a steady rise
in liquid fuel demand over the medium term, and by 2025 it will be
3.5 mb/d above the 2019 level. By comparison, in the World Energy
Outlook (WEO) 2020 Sustainable Development Scenario (SDS),
which maps out a trajectory consistent with global net-zero
emissions by 2070, oil demand falls by 3 mb/d over the same
period. A pathway to net-zero emissions globally by 2050 would
require even sharper falls"

4
Antarctica / Re: Pine Island Glacier (PIG) Calving and Discussion
« on: January 24, 2021, 02:45:37 PM »
I have just completed the diagrams of the Along-Flow speeds with a more detailed view of the upstream speeds: between 60 and 110 km using 2 km sections. In this case to avoid abnormal data I have set minimum conditions to take into account the valuations.

 From this table I will give two presentations: in absolute values (first image) and as differences, in percentage, with the valuation of December 2014 (second image).

I will also take the opportunity to present the Along-Flow velocity diagram, already published in absolute values version, in this new version as differences, in percentage, with the valuation of December 2014 (third image).

I foresee an update in 6 months with the publication of the three diagrams: Along-Flow (20-130 km, 10 km sections), downstream (20-70 km, single section; the "thermometer") and detailed upstream (60-110 km, 2 km section) in both versions. If there are interested persons I could also publish the corresponding tables.

As soon as I have time I will complete with the Across-Flow speed diagram (in both presentations)

Click to enlarge.


Wow! Nice work.

5
“Renewables will play an increasingly important role, with their share of the overall energy mix rising to 15% in 2040,” the AMP Capital report says.

https://www.ampcapital.com/content/dam/capital/04-articles/insto-edition/2019/012020%20Energy%20Infra%20Whitepaper_Spreads.pdf

We need far more wide-reaching changes than are happening now.

6
Antarctica / Re: Pine Island Glacier (PIG) Calving and Discussion
« on: January 06, 2021, 08:14:08 PM »
I follow this thread daily and the increase in velocity is worrying: To me, it looks like the strain along the edges of the glacier can no longer be taken up using ductile flow - and is therefore undergoing brittle failure (rather like an earthquake). My guess is as this happens the resistance to flow from the edges of the glacier will be significantly reduced, leading to an increase in velocity, and propagation of the points of failure; a runaway positive feedback. It's not exactly MICI but there is a similarity: The ice can no longer support the forces that it's subject to and is failing in a brittle and catastrophic fashion.

7
Arctic sea ice / Re: The 2020/2021 freezing season
« on: November 01, 2020, 06:46:55 PM »

I don't contribute often. Kids and work keep me very busy. That being said, there are very few days when I don't look at the numbers presented here, and read through the analysis.

On the basis of that, I gave an improptu "lunch and learn" presentation at work on the slow refreeze of the Siberian seas and what it might mean. it was based on the fabulous graphics and cutting edge insight that is so often the basis for reading this forum. I gave everybody credit as due, but the usernames did raise a few eyebrows!

I think it heightened awareness, and and a few peoples faces fell.

8
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 24, 2020, 09:30:29 PM »
...
Freegrass, that's an excellent cartoon of flow off the shelf edge, but there's one thing that needs updating. All the ice will be first year ice this year. There is no multi-year ice anywhere close to Siberia.


.... and the halocline is much closer to the surface.

9
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 16, 2020, 07:51:33 PM »
There is enough heat in the Arctic Ocean to keep the surface functionally or literally ice-free, we are told, but much of this heat is stored beneath the halocline.  With an ice-free surface, winds will cause the upper part of the Arctic Ocean to mix, making more of this heat available to the lower atmosphere (and beyond).  Stronger winds will remove heat from the surface of the water faster, but these stronger winds will also mix more of the water column.  At some point, with continuous-enough and strong-enough winds, the halocline will disappear and 'all' of the ocean heat becomes available to be transferred to the air.  And if what we're told is true, the Arctic Ocean will cease to freeze over.  With climate change, the "-enoughs" become more and more achievable, as the speed of heat removal from the lower atmosphere to outer space slows due to the thickening CO2e blanket.

If the autumn winds are really just breezes that minimally mix the water, then the water column below the halocline remains out of the picture [the hot plate, with 200 mm of insulation on top of it, on which the tea cup sits has 'no' influence on the blown-on cup of tea].  Here, the surface water cools faster with the breeze - faster than if there is no breeze - with time that heat transfers to space, or is replaced with an 'endless' supply of cold dry air from 'elsewhere'.  So with cooled water and the heat removed from the air above the water, ice can now form.  I'm pretty sure a breeze coming off the continents in October will speed up the surface cooling, thus hastening the surface freezing.

There will always be a halocline in the Arctic because of the inputs of freshwater from the rivers and through the Bering Strait. It is almost an enclosed ocean (like the black sea or the baltic).  The depth and extent of the halocline will reduce as amplification of the halocline through the freeze/thaw distillation process is a lot less effective, and there is more mixing without ice cover.

10
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 16, 2020, 07:39:47 PM »

You ask about "the Arctic" and then concentrate solely on the surface of the ocean. Which is a fallacy. When heat escapes the sufarce on the ocean it raises air temperatures, but the heat is still in the Arctic. And since the ocean will only freeze if air temperatures are low enough, any process that raises air temperatures is going to delay refreeze.



Correct me if I misunderstand - the ocean and air both lose heat through emission of LWIR. Low air temperature doesn't cause the ocean to freeze; rather it is indicative of the physical conditions that cause freezing. If the ocean is warm, then the air above it will be warm as the ocean is so much more massive.

11
Antarctica / Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« on: October 16, 2020, 03:28:04 AM »
In the linked article, Hansen & Sato discuss how in the past five years, GMSTA has accelerated from the trend line from the past half century:

Title: "Accelerated Global Warming"

http://www.columbia.edu/~jeh1/mailings/2020/20201014_AcceleratedWarming.pdf

Extract: "In the past five years global temperature has jumped well above the trend which has been stable at about 0.18°C per decade for the past half century (see figure above). This deviation is too large to be explained by unforced climate variability."

They make the conclusion that the increased forcing is down to aerosols, because all other major sources of rapid forcing have been eliminated. I'm looking forward to reading chapter 33.

My initial thought is if a presumed reduction in aersols has lead to such rapid warming then the ECS has been underestimated.

12
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 14, 2020, 06:19:10 PM »

.....

An immense volume of warm water is still several degrees above the freezing point of salt water from the surface to a depth of 30+m, again out to Oct 22nd, making for some 90,000 cubic km of sea water needing to be cooled (if vertically mixed) by air having only a thousandth the specific heat capacity.

....


... And air with increased humidity to reduce emissions to space.

13
Arctic sea ice / Re: The 2020/2021 freezing season
« on: October 05, 2020, 07:26:42 PM »
Quote from: gandul link=topic=3299.msg288918#msg288918

....Laptev-ESS seas venting out their energy excess?


Right - that is my guess. No insulating ice to allow the temperature to drop.

14
Arctic sea ice / Re: The 2020/2021 freezing season
« on: September 25, 2020, 08:47:22 PM »

And the weather is totaly nuts on the russian islands. As of the 24th, the record of the most crazy anomaly is probably for Ostrov Golomnjannyj. The current mean temperature, 4.7°C, is 4° (!) above the old record of 2012, and even 2°C above the warmest month ever recorded, August 1932. Every day have broken their daily record, 15 days had a Tx above the old monthly record, and even one Tn was above the monthly record of Tx... And all of this with 71 mm of rain (and I mean, really rain, liquid water at 5°C), wich is more than three time the normal monthly precipitation amount. From Ostrov Heiss to Ostrov Kotel'Nyj, crossing Khatanga and Ostrov Vize, mean monthly temperature are going to be 2 to 4°C above previous record, and going to be more than 3 sigma above normal. Seing such and anomaly over such an area (we are speaking of something like more than 2 millions of km² or 0.5% of Earth surface) for a monthly mean is unprecedent.
I attach the snow anomaly map from Noco Sun's website @ https://cryospherecomputing.tk/index.html
and from https://ccin.ca/ccw/snow/current - Snow Cover Extent, which shows almost no new snow in Eurasia this month. (What snow exists is mostly on The Tibetan Plateau / Himalaya)

Snow is a good insulator - so not having any is a good thing as the weather cools. It allows more heat to emit into space. The fact that there is rain rather than snow and there's so much extra heat to lose - now that is very worrying.

15
Sometimes 'Click to Enlarge' doesn't do much for me.  Sometimes it does.  This is one of the "it does" times!

Seriously! That is an amazing image.

16
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: September 16, 2020, 04:43:40 PM »
Oddness in the Central Arctic Sea continues...

Just two out of 14 seas are keeping this melting season open, the Central Arctic Sea and the East Siberian Sea (ESS).
....

and, usually, area declines precede extent declines.

17
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.

18
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 11, 2020, 03:22:16 PM »

My point (somewhat) is that whenever we fit a line we are assuming a model.

In response to A-Team: From what I read I thought freshwater input into the Arctic is largely from rivers e.g.

https://people.earth.yale.edu/sites/default/files/files/Carmack_etal_Freshwater2016.pdf








19
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 10, 2020, 10:48:40 PM »

I think we are in the tail of 1/x rather than y=x. The last sea ice close to the pole doesn't receive that many days of insolation and has a lot of FDD days to thicken the ice. Even in a super hot year, like this year, with melt ponds forming early, we aren't going to break the 2012 anomalous minimum.

The Arctic freshwater lens will persist, as much of it is created by input from the rivers. Only in years like 2012 will the ocean be adequately mixed to melt more ice (and lose additional heat).

To melt that last ice there have to be fewer FDD days and more insulation during the cold months.
Or, like in 2012, mixing melts the ice. At least the latter would help in the long run with additional heat vented.

20
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.

21
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.

22
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.




23
One line in the quoted material caught my attention:
Quote
When the ice sheet shrinks, it will withdraw further and further from the coast and ice discharge into the ocean will become less important.
This phenomenon would apply to East Antarctica, but not to Greenland or West Antarctica.  The later two regions are largely iced over archipelagos, so the ice sheet won't 'withdraw from the coast', in fact, the coast will become more and more icy (less rocky) as the ice sheet retreats (until only a handful of mountain glaciers remain and there is no ice sheet).

There's a huge difference between West Antarctica, which has a great deal of exposure to the ocean and retrograde slopes beneath the ice sheet, to Greenland, which has fewer outlet glaciers to the central portion of its ice sheet.





Greenland appears to be less at risk than east Antarctica, based on the topographic maps with the ice sheets removed.

Are there maps adjusted for PGR?

24
Arctic sea ice / Re: MOSAiC news
« on: September 03, 2020, 03:12:38 PM »

Simon

May I ask what the scale on the left is?

I'm really struggling to see where the base of the ice is!

Would the winter ice be more clearly defined as the freeze causes mixing, the water convecting below the ice layer? As the ice melts the heat is transferred by conduction, leading to a much smoother gradient.



25
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: August 26, 2020, 05:46:08 AM »

Thanks Oren!

26
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!


27
Arctic sea ice / Re: MOSAiC news
« on: August 22, 2020, 07:03:11 PM »

The end result is that ice at the bottom of a melt pond has a mid range albedo, reflecting more than open water, but still transferring a lot more solar energy to the water underneath than snow covered ice.


No, as I pointed out in a response to A-team submerged ice has an albedo of about one quarter of open water.

I thought open water has an albedo around 0.1, so 90% absorption and submerged ice is around 50, so 50% absorption. Open water absorbs about twice as much energy as submerged ice.



28
Arctic sea ice / Re: The 2020 melting season
« on: August 21, 2020, 07:23:20 PM »
Thanks to Neven for kindly updating the year-to-year Bremen map comparison page.
<snip>
I think we are closer to 2012 that people realize.
Without getting too far off topic. Think about it. Even with a virtual tie with 2012 this leaves 2020 a lot worse off, considering how much other permafrost, tundra, glacier ice, Ice sheet, Ice shelf, ect. type ice that has been lost since 2012. All of which served as back up to the world's a/c system.

2012 had the GAC that had the end result of venting a lot of ocean heat, melting ice, and, my guess, is that it lead to the following 'recovery' years of 2013 and 2014. This year is a warm year on-trend. Rather like this year might be the warmest year on record, warmer than the last el-Nino year, 2016, even as we have a mild la-Nina.

29
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: August 05, 2020, 04:49:26 PM »

I'm in too!

30

How high is the snout of the glacier now - do we have any idea?


31
Arctic sea ice / Re: The 2020 melting season
« on: July 28, 2020, 10:37:18 PM »
DMI Norh of 80 Temperatures.

The 2020 high blip first is getting to be a spike. 2016 had a blip around the same date but less above the green line.

Just maybe an indication of central arctic sea ice resistance to melt crumbling? Certainly one to watch?
I'm starting to feel prophetic now... My ego is swelling to exuberant proportions... :o

That can only happen when there is open water inside 80N.

32
Arctic sea ice / Re: The 2020 melting season
« on: July 26, 2020, 06:58:12 PM »
Going back to some of the comments up thread, one of the disturbing things I see in the weather over the next 5 days is the precipitation - up to 5cm in some parts of the Beaufort and Chukchi - falling as rain.

That's a huge heat input and will devastate the thinner ice.  Won't particularly help the thicker either.  It will help with the general weakening of the pack.

A lot of rain will also wash over the CAA.  Not as much, but enough.

Id second that - I think most years you see dustings of snow that slow the melt. This year there hasn't been any.

33
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,

34
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.

35
Arctic sea ice / Re: The 2020 melting season
« on: July 15, 2020, 08:59:12 PM »
...
1.  I think the notion that energy in the open Waters that are very warm next to the ice DOESN'T contribute quite powerfully to melting adjacent ice is utter rubbish.
...

Particularly if there is a warm wind blowing out of Siberia picking up water vapour. Each gram of water vapor melts 4g of ice if it condenses.

36
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.

37
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


38
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: June 19, 2020, 06:31:32 PM »
Area Graphs for the High Arctic Seas from NSIDC Data

Chukchi - after a late start area at 2010's average.
Beaufort - also a late start & area well above 2010's averge.
CAA - also late start at close to 2010's average and about to hit the elbow (someone remind me why this happens?)

Two distinct areas of melt with very different timing?

39
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.



40
Arctic sea ice / Re: The 2020 melting season
« on: May 28, 2020, 05:14:40 PM »
Lowered albedo does increase short wave solar absorption, but also long-wave earth radiation. Since in the winter the latter predominates and in the summer the former, they must be roughly equal somewhere, probably mid-May. Likewise aerosols both cool and warm. As anyone who has had a garden knows, the first frost is on a cloudless night. People seem to be writing about only half of the effects of these phenomena.

I'm not sure I read this correctly; note that emissivity is controlled by temperature and not by colour. Just because something is dark doesn't mean it will emit more radiation. Colour is largely controlled by how the object reflects visible light (unless the object is hot enough to emit light in the visible spectrum). The two properties are unrelated.


41
Arctic sea ice / Re: The 2020 melting season
« on: May 16, 2020, 01:40:03 AM »

...
Is this normal? ...

Perhaps the reduced aerosols are contributing to the reduced cloud cover more than would be expected.  I don't know much about the specifics there but maybe the relationship between aerosol density and cloud formation isn't linear or continuous.
I would think that besides the ~1/3 reduction in global aerosols (I could be grossly off o this # but I think it is reasonable), the 90% drop in air traffic is the biggest contributor to the lack of clouds. Or, the drop in air traffic at this point may be taking primacy even over the drop in aerosols. There was a study after 9/11 that showed a major rise in temperatures when air traffic halted. This is now being replicated much more severely across the entire planet.

Contrails are thought to have a net warming effect, particularly as they form more readily at night rather than day. Clouds keep the planet warm.

https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-19-0467.1

" In contrast, the level of understanding for contrail cirrus impact has been thoroughly upgraded during the last 10 years, and it is currently considered as the largest component contributing to aircraft-induced radiative forcing (Burkhardt and Kärcher 2011; Schumann and Graf 2013; Bock and Burkhardt 2016b; Grewe et al. 2017)."

42
Science / Re: Contrails & artificial clouds
« on: April 28, 2020, 08:58:10 PM »

Contrail cirrus is an interesting problem. Soot from contrails can produce more and wider cloud, and it's particularly prevalent in cooler air.

Current LCA models do not allow for contrail cirrus. If they did they are estimated to increase the GWP 2x to 4x the amount of other emissions.

Contrails act to warm the earth, not cool it.

43
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.


44
Antarctica / Re: PIG has calved
« on: February 11, 2020, 08:02:49 PM »
The relative size of the ice to the water it needs to displace is significant.

Eureka.
The water you need to displace is one to one to the volume of ice under the water. Same mass according to Archimedes.
You would also see significant eddying around the perimeters if the forces of tension from the calving were responsible for the movement. I see mostly  uniform movement rather than the chaos you would expect from internal forces acting at different vectors.


If a 100km iceberg moves 10km, how much water is displaced relative to the size/mass of the ice?  Not 100%!

100% of the mass if the ice is floating, size wise its Volume*(density of freshwater)/(density of seawater).


45
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.


46
Arctic sea ice / Re: 2020 Sea ice area and extent data
« on: February 01, 2020, 01:03:36 AM »

That's what's meant by 'blast past'?

I'm sure he meant February...

47
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.

48
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....

49
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.

50
Antarctica / Re: PIG has calved
« on: January 25, 2020, 06:10:49 PM »
Confirmation from Sentinel-1 that the tip fell off.

That's just the tip of the iceberg from the upcoming calving.

(Sorry. I'm a Dad.)

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