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A-Team

Nevin writes: "Greenland's glaciers and ice sheet have become an integral part of this blog. Perhaps it should be renamed to ASIGIS blog? ;-)"

Ok... here is an updated header image, ;-)!? The tropical cocktail glass (with methane bubbles) looks a bit ahead to future warming.

Photobucket

Aaron Lewis

I love that clip.

It shows progressive structural collapse of big ice as I calculated it. I have been laughed at for 18 years, but now I know the process is real.

I think the data flow and flood of ideas through this blog rivals the best academic venues.

The sea ice and GIS were always related. One could say that Greenland is just an Arctic archipelago with 3 km thick sea ice
: )

David Chase

If the loss rate is accelerating (as it appears to be), there will be more of these. I'm having a bit of a "how's that supposed to work anyway?" reaction. How fast can a disintegrating glacier flow into the ocean? (Not saying it won't happen, I'm just having a hard time wrapping my had around what's possible, and what's not, and what it takes to define that limit.)

Djprice537

I do believe that the same rot that occurs with sea ice will also show up on the GIS as it warms. Just not sure that watching the leading edge of a glacier disintegrate is how this rot will manifest itself on land ice.

I remember my childhood, weeks after a huge snowfall with the snow finally melted. The only snow that remained were these mountains of snow piled up in parking lots, melting and freezing and slowly disappearing.

A-Team

A new preprint characterizing the Arctic cyclone that peaked on 6 Aug 2012 may interest people here who followed the event as it happened.

The article provides attributes for a new row (#1618) in a previously compiled database of Arctic cyclones over 1979-2012, namely the central low of pressure, the laplacian of that pressure (called intensity), storm radius to vanishing intensity, and pressure differential (called depth) from center to edge. These attributes -- notably the 966.4 hPa Z300 minimum on 6 August 6th -- proved quite out of the ordinary relative to the (rather limited) instrument record.

They began by downloading Climate Forecast System Reanalysis (CFSR) data which encompasses atmosphere-ocean coupling, sea ice concentration, miscellaneous atmospheric data, and turbulent heat flux at the surface (later shown to have little role). Since baroclinicity (non-parallelism of pressure and density isosurfaces) is important to the generation of cyclonic systems, its instability was quantitated at 500 hPa via Eady growth rate parameter to get at contributions of an upper-level tropopause polar vortex to cyclonic development and evolution.

Sea ice concentration declined during the 13 days of the event; the authors attribute that to dispersal by high winds of the storm (rather than sea ice decline intensifying storm parameters). As NSIDC notes in their comment piece, coincidence does not establish causality -- the ice was already rotten before the storm.

Where then did the strength of this storm come from? Another Arctic cyclone expert suggests it originated in the strong temperature contrast between warm waters in the East Siberian/Laptev sea with the sea ice edge at 75–80°N. In that scenario, this cyclone could be more or less the new normal.
Simmonds, I. and I. Rudeva (2012), The great arctic cyclone of August 2012, Geophys. Res. Lett., doi:10.1029/2012GL054259, in press.
http://journals.ametsoc.org/doi/abs/10.1175/2008JCLI2366.1
http://nsidc.org/arcticseaicenews/2012/08/a-summer-storm-in-the-arctic/
https://www2.ucar.edu/atmosnews/opinion/steven-cavallo-ncar

Photobucket

Neven

Thanks for the paper and the new header, A-Team!

Glacierchange.wordpress.com

An update to the Qaleraliq Glacier retreat has an animated graph, see video, of ice sheet melt extent from the Tedesco et al (2012) Figure 2a static graph.

Werther

Thanks, Neven,

For publishing my work and for relating the Sermeq Kajulleq-event to Balog's movie.
It is very illustrating!

BTW, I just found this while filing the NCEP/NCAR decade composites:
Photobucket

That is like 'frying' the GIS in december?

Jeffrey Davis

We were in Alaska while that was happening. Watching glaciers calve ice bergs! Except ours were little dinky things: the biggest was maybe 50 ft across its face. Even so, as small as they were, they all had that characteristic crack and grumble sound as they broke free of the main glacier. I can't imagine how loud the calving in that movie was -- the db limiters of the micrphone would reduce the End Times to a cricket chirp.

Aaron Lewis

A-team,
I expect the Arctic cyclone last summer is the new normal. Loss of snow cover on land facilities near shore sea ice melt. The open water absorbs sunlight and warms. Then the temperature differential between residual sea ice and sun warmed water drives a storm.

What happens when the sea ice is gone? Then the temperature differential to drive such a storm is at the edge of the GIS.

What comes to mind is the Great Red Spot on Jupiter!!?? The implications for NH Atmospheric circulation are, well, different from anything published.

Perwilainen.wordpress.com

Thanks for posting the clip of the calving event. It is amazing. However, I do not believe it is from the summer of 2012. Firstly, the movie was probably already cut by then, and secondly, very similar footage is shown in Balog's TED talk from 2009, where he also says that it is the greatest calving event ever recorded. The calving event can be found at 16:16 in the TED-talk from 2009. Well worth watching in full, at the TED website or here: http://www.youtube.com/watch?v=DjeIpjhAqsM

Perhaps some did not know this, but PBS Nova made an episode dedicated to the extreme ice survey. (Season 3/2009 episode 10.) For those with an US ip-address it can probably be watched here:
http://video.pbs.org/video/1108763899/subject/957383708/topic/957390492/tag/NOVA%20Extreme%20Ice

For those with an US iTunes account the PBS Nova episode can be bought for a small amount here:
here: https://itunes.apple.com/us/tv-season/extreme-ice/id319077172?i=336736519

The extreme ice survey website also has many nice stop-motion videos of glaciers acting like giant conveyor belts:
http://extremeicesurvey.org/

Chris Reynolds

Periwilainen,

Well spotted.

Open two windows, one with the video at issue from Neven's main post (A), one with the first Youtube link from your comment (B).

Check out:
A - 1:52.
B - 16:22.

They are clearly the same, though A runs slower than B.

A - 0:50.
B - 16:44.

Here they run the same speed.

A - 2:45.
B - 16:50.

With just one identical shot it could be argued that it was an editing mistake. With three it is clear that this video piece came from at least 2009.

So yes, the video is the same one in the 2009 lecture presentation. It is not from 2012.

marktime

Aaron Lewis: "I think the data flow and flood of ideas through this blog rivals the best academic venues."

I'll echo that: A-teams' post is a good example.

Baie dankie Neven.

GeoffBeacon

On Record dominoes 13 Bluesky posted a letter from the European Commission saying that the IPCC was the body they followed on climate change. He got a more explicit reply than a similar one I received last year.

There was something about a post I made following Bluesky's that preventing it getting posted so I have put a couple of pieces on my BrusselsBlog. The latest piece criticises the leaked draft of IPCC Chapter 9 (Evaluation of Climate Models) that Apocalypse4Real pointed us to. This says

There is very high confidence that CMIP5 models realistically simulate the annual cycle of Arctic sea-ice extent, and there is high confidence that they realistically simulate the trend in Arctic sea-ice extent over the past decades.

I did a bit of work on a part of their figure 9.24 which shows the CMIP5 estimates of Arctic sea ice decline compared with satellite measurements supplied by the NSIDC. I added in the 2012 September sea ice extent. The result has a similar message to the graph shown on this blog under Models are improving, but can they catch up?. This was more extensive and used the CMIP3 climate models.

I just can't see how the IPCC Chapter 9 can justify their claim above and I don't see how the European Commission can support their claim that

The European Commission bases its climate policies on the best available science and on the scientific consensus of experts in the field of climate change. The scientific consensus view on this subject is reflected in the IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report from 2007.

Am I missing something?

Neven

Thanks for clearing that up, Periwilainen. I'll adjust the blogpost.

And thanks to you too, Geoff, for having a look at the AR5 draft as it currently stands.

Aaron Lewis

In 1982, the Barents Sea, just never quite melted. What are the odds that ~30 years later, it will not quite freeze?

If it does not quite freeze this year, what are the odds that it will not freeze again next year? Deming is whispering in my ear that the behavior of the Barents ice over the last 6 years is cumulatively 6 sigma off its behavior from 1979 - 1989. Deming whispers that the Barents ice is going to do something different.

Apocalypse4Real

A-team and Aaron Lewis,

"I expect the Arctic cyclone last summer is the new normal."

There is a new study out on the impact of polar hurricanes. See:

Climate model is first to study climate effects of Arctic hurricanes

Now climate scientists at the University of Massachusetts Amherst and in England report the first conclusive evidence that Arctic hurricanes, also known as polar lows, play a significant role in driving ocean water circulation and climate.

http://www.eurekalert.org/pub_releases/2012-12/uoma-cmi121112.php

No time to retrieve - apologies!

Werther

G'night all,

Well noticed, Balog's film must have been cut before June '12. That leaves a remark on Jason Box's blog the one confirmation.

Nevertheless, the clip is very informative on the specific behaviour of Sermeq Kujalleq.

BTW, another 'not unusual' area anomaly uptick on CT. It may be the SoO failing to freeze, as the MODIS yesterday shows:

Photobucket

Winds are north now, look at the clouds revealing heat release.

Neven

Acronym assistant: SoO would be Sea of Okhotsk.

Werther

Close to Greenland…

AVHHR image Lincoln Sea 15 Dec 2011:

AVHHR Lincoln Sea 15122011

AVHHR image Lincoln Sea 16 Dec 2012:
AVHHR Lincoln Sea 16122012

It may be ‘weather’, it may be I’m getting frantic.
But things out there seem to be getting progressively worse in the dark polar night.

What we see doesn’t show on CT area nor on UB . The AVHRR signal reveals the leads and weaknesses through thin ice and snow.

The pattern is consistent with Nov-Dec mean southerly winds, contrasting with the ‘normal’ climo norteherlies that used to push the pack against Greenland.

The southerlies also accompany ever increasing SIE anomaly in the Barentsz Sea.

John Christensen

@ Werther:

CT is showing a reduction of 150K km2 in SIA in the Arctic Basin from Dec. 12 to 15 - isn't this reflecting the thinning of the sea ice north of Greenland?

Neven

Hmm, a couple of people (3-4) have been mailing me about that ice retreat North of Greenland for a couple of weeks now. I haven't really been paying attention to it, as these things tend to go back and forth. But maybe this is getting out of hand.

Werther

Hi John,

It probably does reflect that. The Basin also misses app. 70-80K north of Svalbard.

Werther

John,
I forgot to mention that it doesn't show on the CT/UB maps.
It does in the CT and IJIS numbers. The deplorable state is somewhat masked through near average refreeze in the Hudson Bay.

Werther

Morning Neven,
I see you're with us too... It could be related to the negative AO. Maybe 'recovery' when it flips in january?

Neven

The widespread cracking is normal, I'd say:

But I'm not sure about all that open water. Not a lot of transport going on through Fram, I surmise, but still a drop in CT SIA. Hmmm...

And what a huge change from the 15th to the 16th in those images you posted, Werther. Is that even possible?

Neven

Woops, forgot to mention that image above is from December 9th 2011.

Here's one from December 18th 2010:

I'm retrieving those images at DMI.

Espen Olsen

I just watched this BBC program, interesting!

http://www.youtube.com/watch?v=YtevF4B4RtQ

Werther

Hi Neven,

AVHHR, ASAR, MODIS...they all have different properties.
Have to take some time to compare...

Neven

Yes. I think I'm seeing it on ASCAT, but it's difficult to tell.

John Christensen

Hi Neven,

I just added a comment with references to two articles - did you remove this entry?

Neven

Hi John, I don't remove comments without reason or announcement (unless they're spam).

John Christensen

Thanks, I will try again then.

John Christensen

Regarding the retreat of the Jacobshavn Glacier:

Take a look at the retreat from 1851-1902, which represented a third of the total retreat, and how the retreat almost halted from 1964-2001, while the atmosphere was warming:

http://nsidc.org/cryosphere/sotc/iceshelves.html

Article:

Acceleration of Jakobshavn Isbræ triggered by warm subsurface ocean waters, Nature Geoscience 1, 659 - 664 (2008)

Abstract:

Observations over the past decades show a rapid acceleration of several outlet glaciers in Greenland and Antarctica1. One of the largest changes is a sudden switch of Jakobshavn Isbræ, a large outlet glacier feeding a deep-ocean fjord on Greenland's west coast, from slow thickening to rapid thinning2 in 1997, associated with a doubling in glacier velocity3. Suggested explanations for the speed-up of Jakobshavn Isbræ include increased lubrication of the ice–bedrock interface as more meltwater has drained to the glacier bed during recent warmer summers4 and weakening and break-up of the floating ice tongue that buttressed the glacier5. Here we present hydrographic data that show a sudden increase in subsurface ocean temperature in 1997 along the entire west coast of Greenland, suggesting that the changes in Jakobshavn Isbræ were instead triggered by the arrival of relatively warm water originating from the Irminger Sea near Iceland. We trace these oceanic changes back to changes in the atmospheric circulation in the North Atlantic region. We conclude that the prediction of future rapid dynamic responses of other outlet glaciers to climate change will require an improved understanding of the effect of changes in regional ocean and atmosphere circulation on the delivery of warm subsurface waters to the periphery of the ice sheets.

The change in the Irminger ocean current corresponds very well to the observed changes in the glacier front, so it would seem that multidecadal changes in ocean currents, would explain what we have observed since 1997, and also why the glacier was thickening before 1997.

Werther

Neven, I like the ASCAT thingy... but it has a low resolution (pixel size maybe 4x4 km.
Enlarging it quickly with Paint (I'm a real pro...) it still shows the 500 km long stroke of thin ice near Cape Morris Jessup, which is black in AVHRR.
On your ASCAT image I could thus trace the remains of the 'Laptev bite' and several other features dating back to last summer.

Up for grabs is what we can deduce from these pics.
I found AVHRR does temperature brightness, ASCAT moisture reflection. MODIS is visible light spectre. ASAR does surface height.

That is my amateur take on the properties.

ASAR mostly shows equal grey, mazed by an intricate crack pattern. Showing 'tight floes', not quality. AVHRR has more contrast grip on the surface. But the blacks are not necessarily open water.

Jim Hunt

Having been following the "Morris Jesup Polynia" for a while, I have noticed that the AVHRR "images" centred on Nord look somewhat different. By way of contrast, here is today's:

Those "blacks" aren't as black!

Werther

John,

The article you link is interesting, but already more than four years old. It is but one of numerous scientific reports. The ones I scan (I cannot pretend to actually read them), usually have one of many aspects in the process as main subject.
Why did you put this report forward?

Werther

Hi Jim,
Maybe the contrast is less because of GOES passages in different strokes/times. It is night out there, but there could still be some temperature 'scattering' by light in the middle/high atmosphere?
Anyway, it is thin ice. The Aari maps show it as 'young ice 0-40 cm'.

John Christensen

Hi Werther,

DMI has been researching the Arctic climate around Greenland for more than a century, and while DMI is certainly not a climate change skeptic institution, they participated in this article with the argument that the main factor (and not just one in many) explaining the behavior of the Jacobshavn Glacier, is multi-decadal changes in ocean currents.

There is another key article on change in ocean current that would explain also to an extent (what extent being unknown) the changes in Arctic sea ice:


Enhanced Modern Heat Transfer to the Arctic by Warm Atlantic Water,
28 JANUARY 2011 VOL 331 SCIENCE, 450-453

The last section of this article is very interesting for anyone caring about Arctic sea ice:

Instrumental air and AW (Atlantic Water) temperatures in the Arctic during the 20th century and beyond display quasi-synchronous multidecadal oscillations that make isolation of the industrial warming trend difficult (3, 21). Basinwide observations since the 1980s detected multiyear events of AW spreading in the Arctic Ocean that featured both a strong warming and an increased inflow to the Arctic (7, 27, 28). Although we cannot quantify from our data the variability of previous AW inflow to the Arctic by volume, our temperature data series and the above observational link suggest that the modern warm AW inflow (averaged over two to three decades) is anomalous and unique in the past 2000 years and not just the latest in a series of natural multidecadal oscillations. Both effects—a temperature rise as well as a volume transport increase—introduce a larger heat input into the Arctic Ocean. Although there is no direct contact of the AAWL with the ocean surface in the Arctic, such an increased heat input has far-reaching consequences. The strong AW warming event in the Arctic Ocean in the 1990s caused a shoaling of the AW core and an enhanced heat flux to the surface (29), concurrent with decreasing sea ice (4). Recent oceanographic data from the Laptev Sea continental margin indicate the impact of warm AW-related water masses on the shallow (<50 m) shelf (30), a feature not observed before in a >80- year time series. The data also provide evidence for a significant heat flux to the overlying shelf waters (30). Even without any modification of the vertical heat transfer processes, the enhanced temperature contrast between the AW and the surface sea water freezing point (increased from ~5 to 7 K as identified here) leads to an increase in the vertical heat flux of ~40%. Any positive feedback mechanism will magnify the effect of this flux increase on the ice cover. Complementing the strong feedback between ice and atmospheric temperatures (1), warming of the AW layer, unprecedented in the past 2000 years, is most likely another key element in the transition toward a future ice-free Arctic Ocean.


Conclusion from this article is that both warmer water and more water has entered the Arctic Ocean over the past two-three centuries, with significant temperature increases from around 1850, stressed e.g. in this part of the article:

AW temperatures since 1890 CE were 4.1° to 6.0°C (mean TSE: 5.2° T 0.22°C) and thus ~2°C higher than during the previous 2 ky. The rapid increase to an unprecedented maximum of 6°C calculated for the surface sample apparently started already around 1850 CE.

Could this be a reason why Arctic sea ice is experiencing such a continuous decline, while the Bering Sea, still with a high latitude, seems to escape the decline at least according to CT over the past decade?

GeoffBeacon

Espen Olsen

I think the BBC is terrible on climate change. (See my TweetsToTheBeeb. But the film you mention wasn't the BBC - it was Channel4. See Wikipedia The great global warming swindle

Werther

John,
As I see it, the seasonal ice cover on the peripheral seas may vary over the years, but don't illustrate a 'main process' leading to a seasonal ice free Arctic Basin.
We have given FI Arthun et al a lot of attention. I could interprete that as a specific warm pulse 2010-11 on what you describe as an enhanced Atlantic influx over the last two-three centuries.

I leave the century timescale for later musing. For now, I find that hard to rhyme with the GHG trend. You're not hinting at 'natural' processes, I hope.

The Bering Sea thing is a phenomenon of the last two-say three years. May have to do with circulation changes/PDO. It won't last. The cold trend hampered through last month, although the Alaskan side is thoroughly frozen.

To end for now, there are parallel atmospheric changes described on the blog FI by Chris Reynolds.
The whole thing is on the treshold of runaway now, completely in line with scientifically modelled consequences of anthropogenic GHG emissions. But unfortunately much earlier than supposed through surprising feedback sensitivity.

Espen Olsen

Geoff,

I was not aware of that, thanks for the info!

wayne

Neven's website is the best blog on sea ice short of the official publications.

It is important to allow some discussion go "outside the box".
As a method to get a feel for what is going on.

The seasonal moulin's on top of GIS are very interesting , having a map showing where they are with the superimposed with underlying topography might be even more revealing. For instance if a moulin pours water on a mountain slope just below, would be like a water slide for ice to slide on.

Greenland is a significant weather player for the entire South of the North Pole 0 to 90 degrees longitude weather all the way down to 60 degrees North latitude. But if it looses significant extent this may change.

Chris Reynolds

Espen,

Channel 4 have just had an interesting programme about the UK's weather extremes in 2012, it concludes a role for climate change in our increasingly weird weather, but gets away without mentioning the Arctic. Just says nobody knows why the Jetstream has been so erratic. Which is BBC Weather's take - use the proximate cause (Jetstream) and avoid talking about why it's changing.

The documentary is available on 4OD here in the UK, don't know if the link will work elsewhere.
https://www.youtube.com/watch?v=SbTc6LZ9KZ4

I'm surprised to see you say THGGWS was interesting. Durkin, the man behind it, deceived, lied, and misrepresented some of the scientists he 'interviewed'. He selectively edited Dr Carl Wunsch to make it look like he was saying the opposite of what he actually said. It's only worth watching as a tour de force of denialist technique.

What is good is that the comments are increasingly unfriendly for the denialists, and the people who post vids like that on Youtube are bona-fide fin foil hat whackos (Going on about the New World Order, and the Illuminati). From a public relations point of view I wish those type every success in getting noticed. ;)

Aaron Lewis

The cracks are the new normal. Today the ice is 3 orders of magnitude weaker than it was 30 years ago.

Given the open water (and wind) on the Barents, there will be swells, and the ice will crack. (http://stratus.ssec.wisc.edu/products/rtpolarwinds/)

In the old days, if the ice cracked, (stress from ice movement) the film of water would refreeze instantly. Now the ice is warm enough that the water in the crack drains out and the crack remains. The next swell pushed the ice apart and you can see the crack. This is ice that has been worked and reworked (http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicespddrfnowcast.gif) It is full of cracks. It just needs a little swell to open the cracks so you can see them.

bluesky

in the following link from Dr. Jason E. Box, there is an interesting update of Jakobshavn Isbræ 2011/2012 year glacier front loss which was the biggest since 2006/2007 at 12km2:
http://www.meltfactor.org/blog/?m=201209

Other interesting information from Thomas et al 2011:
"Progressive retreat of the grounding line resulting from the rapid thinning reduced the basal and lateral drag acting on the glacier [Thomas, 2004], and by 2005 the glacier was thinning by >2 m per year at a distance of 50 km from the calving front, increasing to >5 m per year between 2005 and 2007"

The article is free on Google scholar:
http://bprc.osu.edu/rsl/IST/documents/ThomasetalGRL2011.pdf
and deals also with PIG in Antarctica

Future projections for Jakobshavn are a bit gloomy as the glacier is below sea level up to 75km inland:
"Jakobshavn (and PIG) flows in deep troughs that slope upward toward the grounding line which is retreating into progressively deeper water. This will increase Hw (e.g. water depth)which increases the dynamic imbalance of the glacier, leading to even higher discharge velocities and further inland migration of the rapidly thinning zone. This process could be delayed if a floating ice-tongue were to become re-established in the fjord, but this is unlikely on Jakobshavn, where very rapid highly fractured glacier breaks into small fragment as it becomes afloat".
" Result from a simple balanced model predict a discharge velocity increase to >20 km a-1 in 2015, followed by a decreased by 20% before peaking at perhaps 50km a-1 in 2050-2060" (they also say it is a probable upper limit)
But not the case for other GIS glacier:
"However most Greenland glaciers flow along far shorter deep fjords into ocean and are unlikely to undergo sustain acceleration similar to J."

Klon Jay

Aaron, your link didn't work -- I think it was this:
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

Interesting to see the thick ice pull away from the Canadian Archipelago lately.

Aaron Lewis

Bluesky,
The model used by Thomas et al (2011) does not calculate the kind of progressive structural collapses / calving events seen in the Chasing Ice clip above. And thereby, the model likely, (substantially) understates total ice flow. What their model and discussion miss is that the breakup of the ice is a function of the local heat content of the ice and stresses within the ice.

bluesky

Aaron Lewis
Thanks for the information on what is missing in Thomas et al projections.
Is there any estimation, article, somewhere which includes the impact of break up of ice in function of local heat content? Does it mean that the other tidewater glaciers (with smaller underwater fjords) may also suffer from significant acceleration of velocity too? I thought a projections (for Jakobshavn) of 20 km/year in 2015 and 50km/year in 2050 were already quite scary compared to the current speed in 2010 and 2011, (in Bevan et al 2012)at respectively 11 and 9 km/y (although should have increased again in 2012).

Glacierchange.wordpress.com

A paper in the review stage that I am reviewing this week by Sole et al (2012) indicates that glacier runoff amount influences basal melting of the floating sections of marine terminating outlet glaciers. The more runoff the greater the estuarine circulation which brings more warm ocean water up the fjord at depth. After 2000 GIS melt increased markedly and hence runoff. Given that we have seen acceleration of basically all Greenland Glaciers we cannot attribute this simply to ocean current changes, as these would not influence all sections of the coast equally. "Along-fjord heat transport
towards KG increases significantly with both glacier runoff and coastal water temperature.
A doubling of glacier runoff produces a 29% (48 %) amplification of mean annual
20 (summer) heat transport towards the KG terminus, increasing estimated mean annual
(summer) submarine melt rates from 211 to 273 (842 to 1244)myr−1."

wayne

"The cracks are the new normal. Today the ice is 3 orders of magnitude weaker than it was 30 years ago."

Nicely put Aaron, I would also include the never ending tides since the leads are largely similar in direction with the thicker ice say 20 years ago.

"Those "blacks" aren't as black!" Yes JIm Hunt, IR satellite temperature table table settings should be included with these pictures. It is highly probable that the streamers force the setting
darker in order to see ice topography a little better. It is nevertheless thinner ice as the streamers are seen more consistently.

bluesky

In this, now a bit ancient, video (February 2010, "waking giants, ice sheet in a warming world")
http://www.youtube.com/watch?feature=player_embedded&v=hnVtjnGRyDY#!
Dr. Robert Bindschadler (at around 51 minutes) says that Jakobshavn ground bed is connected to Greenland central depression which is below sea level and that " there is no physical reason … that those outlet glaciers won’t just eat out the heart of the Greenland ice sheet". He also mentions that Helheim glacier might also have a connection with the internal Greenland depression. Although I presume all this is not new for the knowledgeable bloggers here, but I would like to know if we know more about the potential timeline and also geomorphological constraints (as the under sea level depression is mostly surrounded by above sea level mountains), to "evacuate" the ice in a worst case scenario... i know there is the pfeiffer article, but is there anything new since then? Once there is a 50km/y of glacier velocity (or higher?) would there be a kind of bottleneck of iceberg in the Jakobshavn and other fjords, meaning that part of the ice would have to melt anyway before contributing to SLR?
Are we sure that Helheim glacier is connected to the central depression?
Apologies if these questions are a bit out of the blue and have been already treated somewhere else!

Twemoran

Mauri

Will the Sole paper conflict with Christoffersen 2012?

http://www.staff.science.uu.nl/~broek112/home_files/MB_pubs_pdf/2012_Christoffersen_AnnGlac.pdf

Christoffersen seems to favor katabatic winds and warm winters (with prolonged melt season) as the primary drivers at KG - along with lots of AW at the mouth of the fjord.

It seems reasonable that air temperatures, wind velocity & resulting polynias and the melt water would all accelerate glacial melt.

Are you aware of any more detailed bathymetric charts of Kangerdlugssuaq Fjord that might be available? Christoffersen mentions a 450m sill about 10 k from the calving front, but I can't locate it on the charts they show.

Terry

Werther

Hi Bluesky,

In the 2012 Greenland records - thread my prognosis can be found. I have read several differing opinions on the blog last week, that I'll have to contemplate.
On behalf of your questions. As far as I interpreted the bedrock map, that has been published several times on the blog, the Helheim Fjord is not connected to the below sea level part of the Greenland Archipelago.
Nor is the Kangerdlugssuaq Fjord.
They do correspond with 'passages' in the mountain ridge from Cape Farvel to Scoresby Sound.

I'm going to look into the Pfeiffer article you mention.

I've read some alarming stuff in entries above, but I find my own assumptions alarming enough. Fifteen cm SLR in a ten year time frame is going to be tough on coastal management. It will enhance storm surges and saline intrusion in rivers and estuaries. It's going to cost fortunes in the rich societies and lives in the poor ones.

In line with the even worse opinions, I wonder if a part of the melt water will eventually gather in subglacial basins. I'm not sure if that is physically possible (now). In ground/earth, free water drains along pression lines, often more horizontal than vertical.In the GIS, I guess most melt water above the ablation zone stays within firn layers (up to now...).
If not, the ice dam-theory might one day surprise us, FI near the head of the Sermeq Kujalleq/Jakobshavn Fjord. The Watson River bridge collapse would be peanuts compared to such an event.

Glacierchange.wordpress.com

If you are worried about a Connection to the heart of the ice sheet look at the Zacharaiae Glacier.
The Christoffersen 2012 paper does not really conflict. That paper focuses on a single period of retreat. This is different than thinning from more subglacial melt leading to acceleration of glaciers. The mechanism is specific to one glacier and one time period. This is not a mechanism that can be used to apply to most of the retreating outlet glaciers, and thus even if true is not nearly as critical a process.

Werther

Morning all,

Mauri, you mean this paper?

‘ Calving on tidewater glaciers amplified by submarine frontal melting’
Authors: Martin O'Leary, Poul Christoffersen
(Submitted on 6 Aug 2012)

This is the link:

http://arxiv.org/pdf/1208.1296v1.pdf

Bluesky, please show the link to the Pfeiffer article you mentioned?

Mauri, that article was good, I remember.

The connection to the GIS heart should interest all. My worry for the next decade is the southern ‘lobe’ of the GIS. Having thought the central/northern part of GIS ‘safe’ for at least the next 40 years, I noticed the wide ablation zones out there last summer. It doesn’t feel good, either.

From what I superficially read, subglacial water seems to have contributed to the formation of Great Slave Lake in Canada (under the Laurentide Icesheet). It is also present in Antarctica.
It wouldn’t be unexpected to occur under the GIS too (is it found FI through the ice drilling campaigns?). I presume that these ‘lakes’ are quite old.
What would surprise is that recent melt water would have found a way to get to them (I don't think so). Not to mention ocean water reaching there.

bluesky

Werther,

the article:
Kinematic constraints on glacier contributions to 21st century sea level rise.
Science 2008
Pfeffer et al

should be free on google scholar
Chris Reynolds already reffered to this article on other thread

Twemoran

Werther

As I understand it Sole, Christoffersen and Muenchow are all working to understand the fjord dynamics that are drawing warm Atlantic water from the mouth of the fjords up to the calving face of the glacier.

Andreas is finding a strong tidal connection, Sole a strong connection to sub-surface run- off & Christoffersen a link to long melt seasons - with enhanced run off and strong katabatic winds.

I think Andreas has the most complete data from his work in Petermann Fjord. He found anomalously warm water close to the new calving front & two counter rotating gyres that have yet to be explained. If horizontal gyres are a common occurrence it seems this would increase the interaction between ice and water speeding the melt.

Katabatic winds interacting with the water surface would act similarly to winds producing polynyas, pushing cold fresh water away from the ice front to be replaced with deeper warmer water. The multi-layered model Sole uses with cold fresh water being injected from beneath the glacier as well adds another level of complexity.

I have a feeling that all of them are correct & that when they finally get all the I's dotted & the T's crossed all of the above will be found to be a part of the big picture.

Hopefully I didn't misrepresent anybody's position too much.

Terry

Espen Olsen

Terry,

"He found anomalously warm water close to the new calving front & two counter rotating gyres that have yet to be explained."

Maybe the gyres originates from the water tunnel system inside the glacier, earlier reported by ???? (Only remember it was a female)

Chris Reynolds

Werther,

Pfeffer et al, 2008, "Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise"
PDF - no paywall.

Twemoran

Espen

Here's a link to Andreas's blog where he discusses the gyres.

http://icyseas.org/2012/08/22/new-ocean-observations-in-petermann-fjord/

I think that the counter-revolution (sounds political) at different depths is what is so perplexing.

I don't pretend to understand all the factors that are driving the warm waters up the fjords, but I'd think that as sea ice retreats leaving large temperature deltas between the GIS and open water, storms following the coast of Greenland will strengthen driving warm water to the mouths of the fjords & that this will hasten melting/calving.

Terry

Chris Reynolds

Twemoran,

I don't know if you've noticed but I've done a blog post on Arctic warm periods during interglacials. It should go some way to answering the question you asked.
http://dosbat.blogspot.co.uk/2012/12/lake-elgygytgyn-and-arctic-warming.html

Colorado Bob

Re ;
Those slow deep loops in the jet stream when sea ice melts. .......

Russia is enduring its harshest winter in over 70 years, with temperatures plunging as low as -50 degrees Celsius. Dozens of people have already died, and almost 150 have been hospitalized.
The country has not witnessed such a long cold spell since 1938, meteorologists said, with temperatures 10 to 15 degrees lower than the seasonal norm all over Russia.

http://rt.com/news/russia-freeze-cold-temperature-379/

Werther

Morning all,

Bob, can't tell how this compares to the climo yet. But here's the december anomaly. Interesting pattern.
Relatively warm around the Kara Sea and in the eastern Kolyma Region (almost icefree Sea of Okhotsk). Cold in Central Siberia (the populated part near Kazakhstan) and part of European Russia.

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Could be the jetstream, yes.

Werther

On Russian cold...

I did a brief check on the negative AO period 21 Nov-17 Dec. Winter is still young, but promises to offer some interesting analysis later in the season.
Almost split Polar Vortex, tendency towards reverse of 250 Mb winds, steady anomalies. Looks like a variation on 'Warm Arctic-Cold Continent'. SIE/SIA remain on record low anomalies.
Maybe this should go to the 'Weird weather'-thread, Neven?

A-Team

Greenland meltwater ... some interesting items I came across reading 45 full-texts and 60 AGU fall meeting abstracts/posters this week. I'll put these in multiple posts since Typepad has been eating the longer ones:

Where does all that moulin water go anyway? Water on, in or below the Greenland icesheet has favorable google search terms -- supraglacial, englacial or subglacial/basal. Remember the fully instrumented lake caught emptying 45 billion liters down a 980 m crack in 90 minutes? Lots more of that plus satellite monitoring of lake drainages on the whole ice sheet.

How does moulin water get down through a km of ice to bedrock? Seemingly by hydro-fracturing, physics put forward in the 1970's by Weertman: meltwater being considerably denser than ice, it wedges its way down, overwhelming lithostasis (equal pressure in all directions), the ice often being under extensional forces to begin with. This water can exit through previously developed tunnels or more dispersively, lifting great blocks above it.

Lakes are now forming primarily at low to mid elevation on the west side, so are not poised to drain below sea level, central Greenland bedrock map below. But in the spirit of Aaron calling an open Arctic Ocean our version of the jovian Great Red Spot (ie 400 year storm), I nominate the central drainage scenario for China Syndrome (ie floating away the whole enchilada).

There is some water there already, as observed from pressure-melting at the bottom of the NGRIP core. That is, the phase diagram of water slants backwards, so adding pressure at constant temperature (down to 2.7ºC) takes ice Ih to water.

The Greenland icesheet did not melt completely during the even warmer Eemian (previous iteration of the Holocene), that's for certain from multiple ice cores. How much remained, aka how much did it contribute to sea level rise (5 m vs 2m from NEEM) is in dispute.

The image below shows bedrock elevations (no connection to the ocean) vs ice sheet surface vs glacial flow speeds.

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A-Team

Here is a screenshot of this annoying Typepad bug. Like what happened to John Christensen, it says it has posted something when in fact it has deleted it. Seems like TypePad has some secret length screening process. Let's see if it will post its bug:

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A-Team

Now I'll try a slightly shorter version of the real post:

The ice core data has many interesting aspects. The whole of the Greenland ice sheet is sliding downward, distorting ice layers, so they drill along summit ridges to minimize that. After blowing $7 million on NGRIP, they added a requirement that radio echo sounding (Kansas 150-MHz ice penetrating radar) not show liquid water. That track is not synoptic but it shows lots of bedrock overlain by liquid water along its tracks (below).

Layers are aligned across cores via 137 reference horizons: volcanic, soot, and the 25 Dansgaard-Oeschger events. The tephra almost always originates from nearby Iceland or Jan Mayen, the soot almost always from the Taklimakan Desert, carbon black from wildfires is not as evident.

I looked at the record around the fabricated1889 Greenland melt cycle. The most intriguing explanation for that is 1883 Krakatoa (rather than 1881 Beerenberg). Its impacts on climate were complex and long-lasting, including warming of the sea east of Greenland. That particular event injected massive amounts of sulfur dioxide into the stratosphere, the sulfuric acid trace in ice cores.

According to the Dec 2012 AGU presentation (no poster) of drill group leader Dorthe Dahl-Jensen:

"All the ice cores drilled though the Greenland ice sheets ... contain ice from the last interglacial, the Eemian, near the base. It is thus clear that the Greenland Ice Sheet did exist 124,000 years ago in the previous warm climate period where it was more than 5 deg C warmer over Greenland. The difference between the Eemian and the Holocene stable oxygen isotope values have been combined with an ice sheet flow model constrained by the ice core results and internal radio echo sounding layers to estimate the volume of the Greenland Ice Sheet 124.000 years ago. The results show that South Greenland has not been ice free during the Eemian period and that the sea level contribution from the Greenland Ice Sheet has been 2.0 +-0.5 m."

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A-Team

Now the other three short paragraphs of that post:

The NEEM group -- which has been exceedingly secretive -- has hinted elsewhere at even pre-Eemian ice. That would be fantastic news for northern hemisphere paleoclimatology. However there may not be more than a meter of such a core record left anywhere on Greenland.

A paper on the lower core may be hung up in peer review; another Greenland veteran RB Alley questions their figure as rather low, as it puts too much on Antarctica and thermal expansion to account for observed ~5m sea level rise during the Eemian.

In my view, the Greenland delta O18 as Eemian temperature proxy has issues. The whole complex history of that water, its origin, transport, deposition, and processing --- if variable -- could cause systematic bias in stable isotropes here but not necessarily at Vostoc. The other issue is how rapidly end-Holocene anthropogenic melt is coming on. This puts much more meltwater in the system over a much shorter time span.

Here are two oblique framegrabs of Greenland before and after total melt. The latter does not show isostatic rebound nor or the effect of sea level rise on the coast of Greenland itself. However it does a cool job with bathymetry transparency. I would guess it was based on ETOPO1 Global Relief Model bedrock from NOAA, much like the hypsometric map someone donated to wikipedia.

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A-Team

Trying a fourth time with another lost post:

Aaron likens the open Arctic Ocean situation to the jovian Great Red Spot -- a 400-year storm in the Arctic Ocean. Ok, but Great Dark Spot of Neptune toohas metaphorical appeal -- an even windier feature in the methane cloud deck at the latitude of Greenland sometimes compared to the 2011 Arctic ozone hole. The 04 Sep 2009 swell trashed the entire Arctic ice pack (after thousands of km of ineffectual viscous damping and diffraction around Ellesmere). It seems even so-so storms are sufficient for swells to force flexural failure of floes.

If floes melt from the bottom, they also melt from the sides. Those are negligible on large floes or ice packs because the bottom scales as the square of diameter (independently of thickness) but the sides only linearly (but also with thickness). The bottom may have deep channels from brine exclusion but those are protected from advective heat transfer, whereas sides have waves slapping against them. For example, a 100 km x 100 km x 2m square ice floe of MYI has 10exp10 m2 of bottom. For 2.5m of non-freeboard thickness, it has side area of 10exp6 m2, negligible. However if that big floe is now cracked, then broken up by swells and sequelae into 10exp8 small floes of 10m x 10m, the area of the bottom hasn't changed. But now the melt area of the sides is fully equal to that of the bottom.

The observed flexural failure in early Sept 2009 was attributed to two polar-vortex-coupled Siberian cyclones of 990 and 986 haP. I've plotted these below relative to the 1979-2012 Arctic cyclone compilation discussed above for the 966 haP cyclone of 06 Aug 2012. These 2009 events weren't too shabby. And here we are with 3 or more in the last 3 years. (When the multi-year ice is structurally weak and the reach of open water is long, the minimally adequate cyclone may be far milder than 990 haP.) The difference is that the 2012 cyclone arrive a month earlier, giving more time for sub-floe dispersion and subsequent melting. The Canadian observers flagged floe fracture near fall freeze-up for a frieze of first-year with multi-year ice. The former, having lesser freeboard, will accumulate spring melt ponds by gravity, accentuating structural failure as these inevitably drain.

I am experiencing difficulty grasping the scientific case for significant summer ice beyond 2015. The end game instead is very rapid unravelling.

A good prediction track record under-shoots and over-shoots reality about equally but we're not seeing that from climate modeling. In view of the precautionary principle, I wouldn't call that bias conservative but, to the contrary, reckless.

http://www.the-cryosphere.net/4/373/2010/tc-4-373-2010.pdf
http://www.nature.com/nature/journal/v478/n7370/full/nature10556.html

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Neven

Maybe this should go to the 'Weird weather'-thread, Neven?

Yes, perhaps it's time for a new one. I looked at this yesterday (extreme cold for time of year in Moscow), but didn't see any explanation, and can't figure it out myself.

A-Team, if ever you feel the urge to write a guest blog, for instance on the AGU conference, I'd be honoured (mail me and I'll give you guest author privileges). Your comments are better than my posts. :-)

Sam

A-Team - Fascinating!

Do you know where and more importantly when the pine needle is from (when and where was the tree growing)?

All -

I wonder about the slowing and broading of the Rossby waves and the meanders in the polar and continental jet streams.

After the weird late summer hurricane pulled inland over New York as a result of the blocking high over Greenland, and the current extreme cold snap in Siberia combined with abnormal warmth in other areas of Siberia, plus the amazing jet stream loop driven blizzard across the midwestern U.S. (now located near Chicago); is this the new normal for the next few years?

http://hint.fm/wind/

Sam

Chris Reynolds

A-Team,

Thanks for some interesting comments. I too have had a long post go missing recently.

Anyone,

Has anyone read anything trying to explain the substantial retreat of snowline over Eurasia, or for that matter N. America?

Chris Reynolds

Sam,

I think the current cold in Russia can be taken as part of a pattern Judah Cohen has identified. See the first graphic here. There is a larger region over Eurasia that's not been warming with the global trend over winter. I suspect that the severity of conditions at present may be connected to the rapid advance of the snowline in November.

See Rutger's Snowlab for Oct, Nov and Dec. 2009 which lead to the severe 2009/10 winter had a similarly massive dump of snow between October and November (monthly averages). I've also been watching the conditions Werther describes up thread.

However another factor may be coming into play, it's been present to varying degrees throughout December. I've described the Petoukohov/Semenov pattern on my blog here. Currently we have:

Very low sea ice in Barents.

A large high pressure anomaly over that region (well slightly landward).

And the high seems to be drawing cold air from the Arctic while moving warmer air from lower latitudes into Barents, hindering recovery of the ice there. Surface temperatures - difference from average. Note the extreme cold over southern part of the Russian Federation.

This situation has the potential to Freeze Europe in the coming weeks/months.

Chris Reynolds

POSTERS BEWARE.

Typepad is losing comments. Copy your comment text. Post. Do NOT trust the fact that it looks like your comment has been posted. Refresh your browser (normally F5) and double check that your comment has indeed appeared on the page.

PS - my question regards snow line was about May June snow.

Neven

Sorry about TypePad, I have no control over that. If it keeps up, I'll ask them what's going on.

Chris Reynolds

I know you don't, it's a minor issue, and as A Team suggests may only be affecting long posts. Which may be an advantage - enforcing brevity (long posts are a problem of mine).

Harvey Puca

Hudson's Bay has a huge influence on climate in Eastern Canada. The tree line plunges around this big mass of water. Could there be some synergetic effect between Hudson's Bay freezing later/thawing earlier and weather patterns over Greenland?

Aaron Lewis

I would also like to see A-Team as a guest author.

bluesky

Without being connected to the sea, there seems to be some "weaker" way between the central area below sea level and Zachariae, Petermann, Jakobshavn.
Is it absurd to think that a major sub glacial lake could prossively fil the central area, and even above sea level and one burst through one of the 3outlet glaciers?

A-Team

Good questions, Sam.

The needle came from the very bottom of the NGRIP hole. Frozen to the core, I don't see how it could have been contemporary surface contamination (cf the exotic weed problem in Antarctica) or a prank. The web photo is low resolution; the specimen may not be in great condition ... there was bark vs needle chatter at the time. Either way, a botanist could have id'ed it by return email in five minutes max (plant diversity is low at that latitude, the options are few). I couldn't find any further mention of it -- either it fell between the cracks, a paper is in the works, or it wasn't enough to make a paper out of (see below).

Suppose it was from a tree that grew right there at the summit ridge in the late Eemian. Barring some fluke like a wind-swept clearing or debris flow or long distance dispersal, a forest at 3000 meters at 75 N says to me that essentially all of Greenland melted, contrary to their narrative. Conceivably it could have been left over a warm early century in the Eemian or from some earlier 'super-interglacial' provided the Eemian never melted. At 124 kyr minimum, it would not be datable by C14. The date would not necessarily be those of annual layers in which the needle was frozen.

The drill hole was maybe 100 mm in width -- if they hit one needle, what other botanical residues lay within 5 meters of it? I'd say a lot. If it had been my call, I would have melted out the bottom of hole (which was done with) for a few days and pumped it out a few thousand liters for sieving. A needle could blow in from the Greenland perimeter but not branches or roots.They still have a stand-pipe at the drill site, I believe the hole was filled with glycerol for precision temperature measurements the following year.

Meanwhile, at Dye-3 borehole way down south but still at high elevation, they had only a few pollen grains, no macrofossils (eg needles). However metagenomic DNA sequencing (which raises serious contamination issues) got good results on the silty cores. They also PCR'ed bottom debris from GRIP, 3 km under the ice there at Summit. As you would expect, they looked a couple of chloroplast genes (rbcL and trnL) and invertebrate mitochondrial cytochrome oxidase subunit I because of their high multiplicity relative to nuclear DNA.

The amplicons were necessarily short so the plant and animal DNA could only be assigned at best to genus: alder (Alnus), spruce (Picea), pine (Pinus), yew (Taxaceae), yarrow (Achillea), birch (Betula), chickweed (Cerastium), fescue (Festuca), rush (Luzula), plantain (Plantago), bluegrass (Poa), saxifrage (Saxifraga), snowberry (Symphoricarpos), and aspen (Populus). For invertebrates, beetles (Coleoptera), flies (Diptera), spiders (Arachnida), brushfoots (Nymphalidae), and butterflies and moths (Lepidoptera). This wasn't any tundra but rather a northern boreal forest ecosystem.

For DNA dating, they tried beryllium10/chorine36 ratios, single grain luminescence measurements, amino acid racemization coupled with modeling of the basal ice temperature histories, and phylogenomics. These methods gave dates of 450-800Ka which seriously predates the Eemian 130-116 kyr, conflicting with an ice-free Dye 3 site then (because the DNA would not last on unfrozen ground). But they couldn't totally rule out an Eemian date with macrofossils.

That was published 6 July 2007 in Science. That's free full text now at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2694912/. It's been cited 123 times so it's truly shocking to see the way they let people carelessly handle the NGRIP and NEEM cores. There is a very cool profile of lead author Eske Willerslev at http://www.sciencemag.org/content/317/5834/36.full

Sam

A-Team,

Thanks for the great info and the link to the paper.

The results of their analysis look not too different from the boreal forests of Canada or the forests of the Pacific Northwest. The data is interesting too. One million years ago (the early end of their dating window), is about the same time that the paleoclimate shifted from 41 kyr to 105-110 kyr oscillations.

For this material to have been preserved, I imagine it must have gone into pretty much a permanent winter from which it never re-emerged. I suspect that means that most of the earliest ice was lost to compression thawing at the bottom of the sheet.

Perhaps this is a good indication for when the permanent ice sheet first formed on Greenland.

As you suggest, it's too bad they didn't attempt to slurry out more material.

Thanks again. Great stuff.

wayne

The Russian side of the Pole should be similar to the Canadian side when there was much more open water over the Beaufort sea.
Barents is still a similar influence which occurs in phases. When the difference between sea surface temperature relative to surrounding air is greater, Barents gets a steady hovering Low pressure which automatically generates a corresponding High pressure over land to the South. The size of the High is greater than the Low by sphere geography and greater expansion of cold dry air over frozen land. Central Russia colder air is not a surprise. Wide open sea water attracts Lows or maintains them steady.

A-Team Greenland land topographical map suggests the moulins
exist near the peaks or on the seaward side of mountain peaks.
High pressure ice physics is very exotic and likely misunderstood,
but one thing is certain, warmer air surrounds Greenland year round. This affects not only the weather but the temperature of the ice itself. It seems possible that the land to ice interface is finally contacting water and air with consequences which may drive speedier calving. Its difficult to say without further details.


Djprice537

plus the amazing jet stream loop driven blizzard across the midwestern U.S.

Hate to disappoint but that blizzard over Chicago today caused light snow for 4 hours with not a flake on the ground. High today was 47F and current temp is about 33F. We have had a very warm, rather dry late fall.

Artful Dodger

Merry Galactic alignment, everyone!
Maya you have a happy 14th Baktun :^)


Cheers,
Lodger

Chris Reynolds

Thanks for the laugh Dodger.

Happy New Baktun to you too!

wayne

Artful stone circle sketch, happy solstice day for all pagans especially this year to the renewed mathematically inclined Mayans. tal tin be-t-tik.

A-Team

So far, so good here -- windy but I cannot really assign it to calendar risk.

Sam, below is the plant list for the Jensen nunatuks in southern Greenland, the most remote in the northern hemisphere (30 km). Willows (Salix glaucus and S. herbacea) and bog bilberry (Vaccinium uliginosum) are shrubby. The rest are forbs, grasses, sedges, clubmoss and ferns.

No trees, soil too thin. Spruce and pine come ashore as driftwood on the beaches of northeastern Greenland; birch brush (Betula nana) was fairly abundant during the time of Eric the Red, based on Brattahlid or the Gården under Sandet site at Nuuk. That's one problem with paleobotany -> Eemian GIS didn't melt... plants can come in fairly quickly on a geological time scale, as here during the medieval warming period.

However Sonstebo et al provide a leucine tRNA intron P-loop database for 842 species -- the entire circum-arctic flora. This means that ancient DNA sequencing of the NEEM core bottom sediment could capture the overall plant ecosystems that those two layers represent. Not going to find dandelion (Taraxacum) DNA during the Eemian at 3000m if the ice sheet was still there.

http://www.ncbi.nlm.nih.gov/pubmed/21951625,21565110,21817051 opens all three abstracts.

Antennaria, Apiaceae, Arabis, Armeria, Campanula, Cardamine, Carex, Cassiope, Cerastium, Chamaenerion, Cystopteris, Draba, Erigeron, Festuca, Hierochloe, Juncus, Luzula, Lycopodium, Minuartia, Oxyria, Papaver, Phippsia, Poa, Polygonum, Potentilla, Ranunculus, Sagina, Salix, Saxifraga, Sedum, Sibbaldia, Silene, Taraxacum, Tofieldia, Trisetum, Vaccinium, Woodsia

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johnm33

Back when i used to read books i came across 2 or 3 second hand accounts of early explorers finding the remnants of what they initially thought were petrified forests on northern ellesmere, turned out they were frozen solid and once thawed a very useful fuel source.
On Greenland i find it difficult to accept that the central area has no outlet to the ocean, and wonder if since it first became icebound it went through a long period with much greater extent and depth of ice, such that its underlying geology was 'rationalised' allowing it to now, after the loss of it's ice age burden, rise above its former level.

Chuck Yokota

This is off-topic and Antarctic, but I saw this article: http://www.nature.com/news/polar-research-trouble-bares-its-claws-1.12015 about how crabs, excluded from the Antarctic seas for 30 million years by the cold, are now invading due to the incursion of warming ocean waters. The ecology had been free from crushing predators, and many species are vulnerable to being wiped out.

Aaron Lewis

As we reflect on the isotopic ratios in GIS ice we need to consider the state of the sea ice when that snow was deposited. If there was a large amount of sea ice, then there was extended water vapor transport, and the ratio of isotopes reflects the temperature of a large volume of the NH.

However, if there was little sea ice, then the source of the water vapor could have been local, and the isotope ratio only reflects conditions in local storm processes.

At this time, we cannot extrapolate from isotopic ratios in GIS cores to global atmospheric temperatures. Moreover, the cores look back on full equilibrium conditions with all feedback loops stabilized.

However, the current climate system is highly forced, and we have no way to estimate what future conditions will be as the system (with current heat content) comes to equilibrium with all feedback loops stabilized. Our models do not even include ice dynamics or carbon feedback loops, much less correctly solve such loops.

For example, there is a lot of recently acquired heat in the oceans, and we do not know where it is going, or how soon it will get there. Now, this is a highly forced system. In the time of the GIS ice cores, the system was near equilibrium, which results in very different system behavior. We do not have any way of mapping from our system to systems near equilibrium.

My estimate is that feedback loops such as sea ice albedo play a much larger effect on equilibrium temperature than the folks writing AR5 recognize. Current sea ice conditions on the Barents Sea and Disko Sea Surface Temperatures tell us that we are closer to a year round, sea ice free Arctic than the conventional wisdom of climate science had guessed.

At this point, I think that once an Arctic sea melts in the summer, feedback loops bring it to year round ice free conditions in less than 20 years. Thus, if the Arctic sea ice melts in the summer in the next 3 years, we could see year round ice free conditions by 2035.

Along the way, there would be some loss of permafrost.

Kris

Chuck Yokota wrote:

about how crabs

Now we not only know where the body snatchers are gone to, but on top of that they have disguised themselves Neolithodes yaldwyni.

Just kidding.

Anyway, a most interesting and reveiling article.
Thank you chuck!

VaughnA

bluesky, If you have ever driven through the Clark Fork River Canyon in Montana you will notice that it is a narrow downhill sloping canyon exiting the large basin that otherwise confined Lake Missoula. Sounds pretty similar to the outlet fjords in Greenland.

Ghoti Of Lod

On the topic of Greenland and Antarctic ice sheets contribution to sea level rise past and future Richard Alley's talk is well worth watching.

http://climatecrocks.com/2013/01/05/the-weekend-wonk-richard-alley-on-ice-sheet-stability/

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