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crandles

>"Sorry if I've wasted your time"

No problem. If my replies help then great. If not feel free to ignore me - I am certainly not an expert.

Apocalypse4Real

Aaron, Jim Hunt, Donald, and others,

Apologies for lack of access earlier, I reset the permissions.

You should be able to access the CH4 and CO2 pages still in construction. The link is:

https://sites.google.com/site/a4r2013metop2iasich4co2/

The top tabs will take you to the pages.

I will be adding the Jan 14 information tomorrow and more CO2 runs later.

Twemoran

Chris

The seasonal albedo chart you posted is eye opening & probably holds the answer to the changes seen since 2010. What I'm interested in is the amount of energy required to melt say a cubic meter of FYI, 2nd year ice & other ages of MYI. My hope is that we could quantify both the energy expended annually up to present assuming we could accurately age the ice that has melted, as well as make predictions regarding future ice loss.

It's well known that FYI melts easier than MYI & I'd assume that someone has quantified the differences.

Albedo changes and increases in GHG's would have to be added to whatever figure was arrived at & physical changes such as the opening of the CAA would have to be taken into consideration so I'm not sure that even if we had an accurate figure we'd be much closer to resolving the question of when the ice will be gone.

I do feel that when we've lost seasonal ice the changes will ramp up considerably due to latent heat of fusion being released as sensible heat & that a permanent loss of the polar cap won't be far behind. I'm not convinced that modern civilization can survive these changes.

Terry

wayne

Werther, other words for slush is Baffin Bay ice, which by coincidence is becoming very relevant considering that Baffin Bay has certain weather related features which may overtake the entire Arctic ocean area given that its ice may be purely seasonal as well. I make a brief dissertation on what happened and what hints are observed for what will surely follow. http://eh2r.blogspot.ca/

Werther

Morning Wayne,

Read your blogpost. Especially the buoy drift map is an eye opener. Moving strong in the Beaufort Sea and in the part of the CAB to the North. Even piece of what I call ‘structured sheet’.

It fits the ARC ice thickness chart. 16 Jan ’12 showed 1.8 m FYI in the Beaufort, with a MYI tail up to 2.5 m. Today it is largely 1.2 m.

To maybe explain what I wrote last evening; ‘I dismiss anything not in the CAB’. That was about the relevance of remaining ice come next August. Not the relevance of these regions weather wise.

The course of change in Baffin Bay and the East Greenland Sea is important for CAB weather and crucial for the GIS.

Werther

Elaborating a bit more on DMI temp over 80 dN.

At first glance the corresponding NCEP/NCAR composites dec-mar ‘10/’11/’12 do not show the same 1:1,07:1,81 correlation. It’s more like 1:0,81:1. Bottom line: all information confirms the Arctic warming shown through GISS.
For this winter: up to now it fits in on pace to 1,59 (Composite). And I think the DMI graph parallels that. It may better get cold in the second part of winter.

Another aspect is the concentration of this ‘warmth volume’ on the Svalbard-Severnaya Zemlya side. Both in ’11-’12 and this winter.

Rob Dekker


Guys, what a great discussion. I'm sorry that I've been absent for a while. It's been busy.
Chris Reynolds made a very interesting comment on the difference between FYI and MYI (from Perovich & Polashenski, 2012) :

Chris said :

Taken over the melt season a meter squared of FYI gains 1/3 more energy when it replaces MYI over the same square meter. That's from 900MJ/m^2 to 1200MJ/m^2. As this factor applies mainly from June to Sept it's an increase of about 38W/m^2

This shows the strength of summer albedo feedback, which is going to be crucial in determining what will happen when all ice is FYI (which more or less is already the current state).

Allow me to put in my reasoning :

First of all, this extra 38 W/m^2 absorbed during summer will have to be shed during winter, in order for this to be a "stable" state. Winter is longer than summer in the Arctic (by something like 210/150) so winter needs to shed 27 W/m^2 or so. Still, that means that winter needs to warm up very significantly (probably some 8-13 C increase needed depending on how much heat transfer to lower latitudes responds).

And note that winter warming will reduce winter ice volume accumulation, which means that FYI in spring will be thinner, which will make it melt out earlier the next summer.

So, in a state where most ice is FYI, the winters will be warmer, and the FYI will be thinner, and melt out faster, as compared to a state where there is a good amount of MYI still present.

If FYI is thinner, and melt out earlier, the amount of heat absorbed will increase rapidly (moving into the bulk of the COS function that isolation follows).

Thus, the transition from MYI to FYI really gets albedo feedback to kick in stronger and stronger the earlier the melt-out occurs, which is self-amplifying due to the winter warming necessary to get rid of the heat.

So, as I argued before, the state of "mostly FYI" may be (close to) unstable, and thus lead to a rapid decline to all-summer ice-free state.

Werther

Hi Rob,
Yes, that is what we fear. And what Lodger introduced some time ago from studies about 'bifurcation'.

Wipneus

Bob Wallace:

I wonder if there is a site that plots estimates of monthly ice flow through the Fram?

I have attempted to estimate this from the PIOMAS gridded data (1978-2011).

I took the shortest crossing with adjacent gridcells across the strait.

Then multiplied velocity-component in the SW direction, with ice thickness and length of the gridcell.

This gives an ice transport in m^3/sec. Taking months as 365/12 days, gives the graphic here:
https://sites.google.com/site/arctischepinguin/home/piomas/grf/fram.png

(red line is annual average of monthly transports)

crandles

Very interesting Wipneus :)

The spikes don't look quite evenly spaced. Is it possible to add 4 lines for average of each of 4 seasons?

A breakdown between speed, concentration and thickness would also be nice but I don't know if/how you can/would do that.

Apocalypse4Real

Regarding Baffin Bay:

The area has had higher CH4 readings for December and January, when the METOP 2 imagery has been available.

For a CH4 example, see the Google Earth images for January 9 am and pm (the CH4 for Jan 13 is coming):
https://sites.google.com/site/a4r2013metop2iasich4co2/home/2011-airs-ch4-359-hpa-vs-iasi-ch4-970-600-mb

For CO2 levels, see the Jan 13 am image: https://sites.google.com/site/a4r2013metop2iasich4co2/home/metop-2-iasi-daily-co2-concentration-maps

Addititionally, the area has had higher than average surface air temps.


Apocalypse4Real

A new study out concludes that black carbon - soot is the second highest contributor to global warming:

In the abstract, the 31 authors conclude:

"We estimate that black carbon, with a total climate forcing of +1.1 W m-2, is the second most important human emission in terms of its climate-forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing."

The report is 232 pages long and covers Greenland, Arctic, and other regional albedo calculations. See: http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50171/pdf


Wipneus

Per crandles suggestion, added 4 more lines, one for each season, conveniently (for me) starting with Jan-Mar.

https://sites.google.com/site/arctischepinguin/home/piomas/grf/fram.png

crandles

Thanks Wipneus. :)

Apocalypse4Real

I have added the CH4 GE maps for the Baffin, Barents and Kara sea area for Jan 13 am at 586 mb.

https://sites.google.com/site/a4r2013metop2iasich4co2/home/2011-airs-ch4-359-hpa-vs-iasi-ch4-970-600-mb

There are high CH4 concentrations (as high as 2122 PPBv) in all three areas, and in parts of the Russian Arctic.

Ron Mignery

Wipneus

Would it be correct to conclude from your Fram flow graph that the annual average volume is essentially unchanged since 1977 despite the thickness of Arctic ice at the start of the melt season having dropped by about a third since 2005 and I presume much more since 1977? If the ice is getting thinner why is the volume not dropping?

Wipneus

Ron, I am just playing with the numbers.

My guess is that the answer to your question is the increased mobility of the thinner ice.

If you haven't seen it, look at Jennifer Francis. She mentions thinning ice->increased Fram export a couple of times:
http://www.youtube.com/watch?v=RtRvcXUIyZg

Another factor maybe the AO, suspected to play a role here.

crandles

From the news sidebar:
http://www.sciencedaily.com/releases/2013/01/130114092521.htm

"Most of the sea ice that leaves the Arctic, exits through the Fram Strait. In recent years, this ice export has been higher than in any decade between the late 1950s and up to today. The area of the ice floating through the Fram Strait is now about 200 thousand km2 larger than in the late 1950s, which is similar to the total area of the United Kingdom.
...
Because the models show different outcomes for the ice export, it is possible to investigate how the Arctic sea ice responds to an increase or decrease in the export. According to the model with the largest number of simulations (10), we find that a thinning of the Arctic sea ice is associated with an increase in the ice export, whereas a decrease in the ice export is related to a smaller thinning. All simulations underestimate the thinning of the Arctic sea ice compared to observations. This means that the simulations would have been closer to the reality today if they were able to reproduce the increase in the Fram Strait ice export."

Looks like you have disproved the bit about models within 2 days of it being posted.

Wrongly propping up failing models; is this an example of modellers believing their models over reality?

Ron Mignery

I guess it makes sense that the volume of ice out the Fram would be constant since the energy to move the ice (the wind) is constant. The implication then is that there is no negative feedback foreseeable in this process (until it clips at zero, of course).

Wipneus

I am quite pleased with the next graph myself. Even if there are some rough edges that I have to look into yet.

Some one asked if the exponential fit to the PIOMAS September data could be done for the different Arctic sub regions.
I have done it better, I have calculated it for each grid-point that had some (>5cm) ice in September 2011.
The fitting algorithm failed in a couple of places: probably the decline is not exponential enough. These area's are grey, the rest is coloured as the year that the "expected" ice thickness goes below zero.

Here is the result:
https://sites.google.com/site/arctischepinguin/home/piomas/grf/zero.png

Boa05att

^ Awesome! I can see why you'd be quite proud of yourself Wipneus :-)


I thought you all might be interested in a recent review by the U.K. Government on the decline of Arctic sea ice:

http://www.publications.parliament.uk/pa/cm201213/cmselect/cmenvaud/858/85804.htm

They conclude "Based on observations and available climate model evidence, we do not anticipate a complete "collapse" of sea-ice cover in "the next few years", with the late summer Arctic Ocean being essentially free of sea-ice being the norm as early as 2015 to 2020. However, assuming greenhouse gas emissions continue without significant reductions in the near future, recent modelling experiments indicate that the Arctic may become essentially sea-ice free for some days or weeks in most summers, at some time after 2030 and before 2080, with increasing indications of an earlier, rather than later date."

It seems as though if you lot are right, they'll be in for quite a shock.

Bfraser

Just pointing out that crandles didn't disprove the paper. The paper said "increased area" and crandles demonstrated "near-constant volume".

I bet both are correct.

Chris Reynolds

Twemoran,

The albedo issue doesn't really address the volume behaviour since 2010. It has more significance when looking at CT Area, in which case the anomalies crash in early June in 2012 and 2011, less so in 2010 itself. The changes post 2010 were still ongoing in 2010, so albedo and particularly melt pond formation (which can fool satellite sensors and account for a drop in area) seem to play a role.

However the spring volume anomaly crash starts around 20 April and ends around 29 June. This is too early for the albedo changes found in the research I cited.

Rob Decker,

Your closing comment is what's consuming me right now. I too am persuaded that a FYI ice pack is not a stable state. The issue for me is how to demonstrate this strongly.

Wipneus,

Impressive work on PIOMAS, thanks. You're making far more progress than I have.

Bfraser

@Boa05att

It may not be as much of a shock as you claim, as they also say:

"The general view that the ice-cap is not at risk of a summer collapse in the next few years may need to be revisited and revised."

Kevin McKinney

"If the ice is getting thinner why is the volume not dropping?"

Mmm. Dunno, and I'm not sure I care all that intensely.

But turn the matter around. The obvious implication is that the proportion of total SI volume being exported annually is rising.

idunno

Bravo Wipneus!

I think it might make your map clearer, and sort out the problem with the palette of colours, if you changed the scale to 2012/13/14/15/16/17/2018-24, or some other cut-off point.

Also interested in when the ice extent falls below the oft-used technical definition of "ice-free" @1M km squared. Which year is this, and what does the map look like in that year?

Wipneus

idunno:

I am still working on it, colors are coming from some default still.

The graph works with ice thickness, not area.
Also going further in time, the projections become more uncertain. North East Greenland seems to have the slowest decline, but if the central basin gets seriously depeleted, those Fram exports must go down as well.

But if this graphs is any indication at all, "virtually ice free" will be well before the end of this decade.

crandles

Another Bravo to Wipneus from me too.

There is a hint that the last remaining ice is split in two with a patch by the North Pole and a patch against Greenland almost heading out the Fram strait. My first thought was this Fram Strait last refuge ice cannot get to become MYI to start a recovery and it seems unlikely location for last refuge. I suspect what is happening is that because thick MYI is being pushed towards this position in the past then the thinning trend tends to be slower than what might happen in reality: When areas that supply ice to this area lose their ice then the supply of ice is reduced and the thinning of this ice suddenly accelerates. So I suspect a last refuge nearer Greenland than in Fram Strait

Also I think it is worth noting that the heat budget balance is not maintained. When an area runs out of ice the thinning just stops. In reality the heat is available to melt other ice and speed up thinning in other nearby? areas.

I can image that some grey areas have upward trends. Those are likely to quickly become rapid thinning trends when there is less ice to move into those locations.

So lots of places where volume will crash much faster than indicated by those trends.

Although some dates are beyond 2020, a 2016ish date for all ice to melt remains more likely.

Thanks again Wipneus. :)


BFrazer, Yes paper talks of area - guess what I said was misleading and I should be more careful. Sorry. Modelers have to look somewhere for the problems and if there is a problem that speed of movement of areas isn't increasing in some models as it should then it is valid to point to this as an area that those models can improve.

Simon

Excellent map, Wipneus, deserving of a prominent home on the long-term graphs page. Many thanks for all the hard work behind it.

Bfraser


The paper said "increased area" and crandles demonstrated "near-constant volume".

I bet both are correct.

Seconded.

crandles

Has anyone already linked to top weather/climate events of 2012?

Arctic sea ice extent judged top
http://www.ncdc.noaa.gov/sotc/global/2012/13

Rank Event When Occurred
1 Arctic Sea Ice Extent Late Spring Through Fall 2012
2 Agricultural Drought Summer 2012
3 Hurricane Sandy October 2012
4 Super Typhoon Bopha/Pablo December 2012
5 Northern Hemisphere Warmth Throughout 2012
6 Greenland Ice Sheet & Glacier Calving July 2012
7 Eurasian Continent Cold Wave January/February 2012
8 Northeastern Brazil Drought First Half of 2012
9 African Floods July - October 2012
10 Antarctic Sea Ice Extent September 2012

Tommi Kyntola

Wipneus, awesome graph, but few questions. Did I get it right that you've fitted an exponential decay for each cell separately and independently?

If so, isn't that likely to underestimate the melt because the positive feedbacks from molten regions don't get fed back onto those still frozen?

Sorry if I've misunderstood it somehow, I just started wondering because (judging with an eyechromometer) it looked like a slower melt than what the typical piomas exponential fits have been.

SATire

Wipneus,

I really appreciate your picture. You know, I really love your exponential fit because it is also the result of the simple albedo-feedback rate equation. But I always thought, the area north of Greenland/Ellesmere must be cooled efficiently by wind and that ice would last longer there than 2015. So - looking at regions seperately makes things looking much more reasonable than looking to broad at the hole arctis. Thank you very much for that picture.

Bob Wallace

Great display Wipneus.

My eyeball, semi-trustworthy as it is, tells me the annual volume of ice transported out the Fram is holding roughly steady.* If that's the case then Kevin hit the nail dead center -"the proportion of total SI volume being exported annually is rising".

This,then, would be an additional accelerating event and, with the Fram being so totally opened up, should empty out a lot of the remaining ice.

--

* A 'best fit' line based on annual totals would be interesting.

Tor Bejnar

Very interesting map, Wipneus! You deserve to be proud.
As idunno inquired, when (approximately) is the 10^6 km^2 area crossed, according to these 'cell' projections?
As Tommi K noted, melted-out areas will surely accelerate neighboring ice-coverred areas, as areas next to open water are more prone to melt than are areas far from the melt edge, and much of the CAB has never been near ice-free sea.

Bob Wallace

Nothing personal Wipneus, but I don't believe that red and deep blue, 2020 to 2024 stuff.

Take a look at this video that shows 1980 to 1995 sea ice movement. You'll see the older ice which tends to get lodged against the Canadian Archipelago get shoved up away from land and then flushed out.

http://www.youtube.com/watch?feature=player_embedded&v=Co68_tod0dQ

I continue to think there is a critical threshold, when crossed, will mean that what ice is left will simply be shoved out leaving the Arctic ice free quite abruptly.

If we melt/transport all the red-orange, orange, yellow and green ice there just won't be anything left to keep the last remaining bits and pieces from getting pushed up by wind coming up from the south and then, if it clocks around some to the west, a cleansing event.

Wipneus

Thanks for the encouragements, I am glad you like it as much as I do.

- grey's have disappeared now. Note that "2024" should be interpreted as "2024 or later". Colors used may change still.

- I am curious about the area for different years as well, including "virtually ice free" limits.

- exponential decline has already considerable acceleration/feedback "built-in". I am not sure how much additional acceleration in the Arctic Basin is to be expected. There may be none.

- I am not worried about the blue's and beyond. I do notice that these are all near the "drains" of the Arctic and most of it is ice that is being flushed. When there is nothing to flush left, it will go suddenly. OTOH it is the only place where that really persistent ice refusing to melt might be lurking.

These are extrapolations. Reliability should be best for the reds and oranges, floowed by yellow and greens. For blues and beyond a lot may change yet.

PIOMAS is based on an ice model. You can expect "features" not found in the real world.

Rob Dekker

Wipneus, that graph is really scary, and makes my bet with William Connolley for 2016 extent being smaller than 3.1 M km^2 look conservative.

I know that from basic principles of feedbacks, albedo feedback is just getting warmed up (so to say), and based on simple calculations we may even conclude that September ice free state is imminent. Beyond that, we may even argue that FYI is not stable and will rapidly progress to an ice free summer, and I would be the last one to argue against that scenario, since I don't see any negative feedback strong enough to compensate for the relentless downtrend in volume that PIOMAS suggests.

But before we reach an ice free (< 1 M km^2) September, which may happen as early as 2016 in Wipneus' graph, can we all think about what we will say to the world when that happens in that timeframe ?

After all, Neven's ASI blog is referred to more and more often nowadays, because of the high quality reports from the Arctic.

I guess what I'm trying to say is, are we ready to answer the obvious questions when one of these summers ice is obliterated far beyond 2012's retreat :

- Was this caused by this storm (the "Even-Greater-Arctic-Cyclone") in August this year ?
- How come you guys predicted this while IPCC models projected this state 40 years later ?
- Is this caused by manmade GHG's or just a fluke natural variability event ?
- Will ice extent be more variable from now on, or will increased albedo feedback reduce it even faster ?
- What does this mean for NH weather ?
and
- What happened to Santa this year ?
- Who is Wipneus, and why does he seem to be spot-on all the time ? ;o)

Etc. Etc.

Bob Wallace

"it is the only place where that really persistent ice refusing to melt might be lurking"

I don't see a safe haven. We observed MYI exiting via the Canadian Archipelago this last year. The loss of snow on the land masses will mean lots of heat to melt anything that gets into the narrow channels.

And the video I posted at 7:01 shows 'top of Greenland' ice in previous years being shoved northward/away from Greenland and flushed.

I used to believe that there would be a persistent patch of ice laying against Greenland and the CA but I'd no longer bet on that.

Wipneus

work in progress:

- some colors changed to increase contrast between colors; I can surely see rabbits popping up ;)
- fixed a bug in the color legend: a shade of blue was missing; "top" color is now 2025

Area calc (Mm^2):

year area
1 2010 4.2786526
2 2011 4.0256911
3 2012 3.6955223
4 2013 3.3294841
5 2014 2.6737849
6 2015 2.1740662
7 2016 1.5691937
8 2017 0.8421968
9 2018 0.5430431
10 2019 0.4199527

The 2012 value would have been the top in the SEARCH Sea Ice Outlook predictions.

crandles

Bfraser wrote:

>"It may not be as much of a shock as you claim, as they also say:

"The general view that the ice-cap is not at risk of a summer collapse in the next few years may need to be revisited and revised." "

That is what the report says i.e. scientists saying it may need to be 'revisited and revised'.

Boa05att quoted the governments reply to that report which was 'we don't anticipate collapse ... ' which seems to me to be brushing aside the scientists saying 'revisit and revise possibility of collapse in next few years'.

That sort of brushing aside of scientists as if their high standing as politicians makes their views important enough to overrule scientific views annoys me. Of course if it was just one or two scientists with a minority view, it would make sense to brush it aside. If it is the mainsteam scientific view then it is highly inappropriate.

Mike Constable

Very impressed by Wipneus's map, but I can imagine that at the end of the year it will need revising if us "warmists" see what we expect. The past year's melt surpassed almost everyone's expectations on this site (>95%?).

Perhaps the map will become a classic, showing a "conservative warmist" assessment of the situation this winter?

When the ice disappears in a summer soon, Watts and his team should be able to answer his question (WUWT) - "No ice" - unfortunately! (Unless he says "What ice?" - then we will be able to say "Watts's ice is another name for water"?).

P-maker

Bob,
supporting your line of thinking, I just wanted to add a few thoughts on recent atmospheric circulation changes observed this past year.

If we see another year with an extended period of anticyclonic circulation centered over the Greenland ice sheet (being the only solid chunk of cold ice left in the NH), and if (during the same summer season) we see one or more persistent central Arctic cyclones, we can expect a convergence of two powerful wind fields north of Greenland, which will flush out remaining MYI before we know it.

Donald

Wipneus, a couple of naive questions --

Has anyone else built (and published) a similar sort of model or are you the first?

Am I correct that the red at the bottom of the scale represents ice lost during 2011 and that the first projection of ice to be lost according to this model is the orange color (third up from the bottom of the scale)?

Thanks

Apocalypse4Real

Wipneus, Werther, Chris, and others who have contributed to the conversation in this thread in regard to Arctic melt and modeling.

Personally, I think what has been produced here could be a peer-reviewed journal contribution.

Wipneus, thanks for sharing what you have modeled, it is a baseline for what we observe in the years to come.

Wipneus
Am I correct that the red at the bottom of the scale represents ice lost during 2011 and that the first projection of ice to be lost according to this model is the orange color (third up from the bottom of the scale)?

Yes, that is how it is calculated now. Since this is all about September thickness, the real ice line-of-extent only matches the graph in September. That line should fall somewhere in the middle of the colored band.

Ron Mignery

P-maker

...If we see another year with an extended period of anticyclonic circulation centered over the Greenland ice sheet (being the only solid chunk of cold ice left in the NH)...

Is the GIS really cold? At an average altitude of 2,135 meters, a standard lapse rate of 6.4°C/km makes the GIS at 0°C no colder than sea level at 14°C (57°F).

P-maker

Ron,
you are absolutely right!. I checked a few stations on this map:
http://jupiter.geus.dk/promiceWWW/map.seam and for all high lying stations (around 1.000 masl) during high pressure episodes last summer, the air temperature was around 5 deg C. However, I was actually referring to the ice temperatures (at 1-10 meter depth), which were still pretty cold in May in most places, but soon reached melting point, when the first high pressure episode occurred.

Ron Mignery

Nevertheless there seems to be little area of effectively cold ice to hold a stationary high over Greenland. Also does it suggest that Arctic Summer temps will rise over 57°F when the Summer sea ice is gone before the GIS has any moderating affect?

Twemoran

Wipneus

Another great graph for us to work with!

Am I correct that you're projecting average September area not minimum?

I'd have expected quite a drop when minimum = 0 and the next year all the ice is FYI with the albedo, melt point and mechanical problems that implies.

Terry

Wipneus

Terry, yes PIOMAS gridded data come as monthly values.

Wipneus

Work in progress, bug fixes:

- meaning of colors have changed: edges of the colors correspond now to September. So the outer red edge is September 2011, edge with darkest orange is September 2012 etc.

- Calculation of ice "extent" was 8 months off. "Virtual zero ice" should now happen in 2018.

- some places the curve fitting was found not to be robust (eg. resulting in negative thickness). This fixes some open water north of the Canadian Archipelago.

https://sites.google.com/site/arctischepinguin/home/piomas/grf/zero.png

Hans Kiesewetter

Nice work Wipneus!. Also nice to see that the sum of Exponential fits for all grid cells results in a Gomperz fit for the total.
The location of the blue spot is also remarkable.(Is it?) Sceptics will continue for many years: "there is still ice on the North Pole".

SATire

Hello Hans Kiesewetter,

"nice to see that the sum of Exponential fits for all grid cells results in a Gomperz fit for the total"

I would not give to much on that tail. As Wipneus put it: Long therm extrapolations are quite uncertain. As I would like to put it (and someone else did here before, if I remember right): That stable-looking Greenland-sea-ice is usually multi-year ice originating from artic basin travelling on its way south. Once there is no ice in the arctic basin, this ice has no origin anymore. And that "stable" ice north of Svalbard will probably vanish this year already - I think those fits must look really odd together with the data.
The fits can not know these things and therefore, that tail is really in some danger... But luckily, we do not need to discuss to much about which "negativ-feedback-miracle" is doing a strange job here.

Ron Mignery

Could not Wipneus' map be enhanced to account for standard ice drift to correct the anomaly of "the blue's and beyond...near the 'drains'"? That would surely chop off the Gomperz tail.

Chris Reynolds

Hans Kiesewetter,

As Crandles suggests further up thread, these long persistence ice areas probably relate to movement of ice.

Off the north east coast of Greenland and across from there towards Siberia relate to movement of ice into the Fram Strait and the transpolar drift respectively. So what is going on here is that ice thickness doesn't drop so much because they are constantly replenished (to a degree) by influx of new ice. In both cases much of the new ice being from the Siberian sector in winter. Where ice movement is away from the coast opening leads that freeze, making new ice. The ice is then entrained into the transpolar drift and driven towards the NE coast of Greenland, where some ends up off the Canadian Arctic Archipelago (CAA), some exits through Fram.


The situation off the CAA interests me greatly. In some years we have indeed seen the region's flaw lead opening up a large bite of open water here. Land warming may indeed cause such warming. However this region is still subject to much ridging and influx of new ice as outlined above. So I am initially sceptical of the projection in this region. The 2010 volume loss was largely in this region, being a massive thinning of the ice there. I wonder how much this event has biased the trend downwards giving an earlier loss date than may actually happen.

SATire

Hi Ron,

"Could not Wipneus' map be enhanced to account for standard ice drift to correct the anomaly "

I am sure, he could, but I think, he shouldn't. It is more convincing to use a straigth and clear analysis and then discuss possible effects and uncertainties. Maybe a additional map showing a possible effect of movements could be used to explain that discussion - but to many corrections based on assumptions do not really help to understand but give a lot of good reasons for critics on the hole picture. That would be really a pitty, because the picture is useful.

Rob Dekker

Regarding bifurcation of Arctic sea ice states, and specifically if a seasonally ice free state in the Arctic is stable or not, I took a much closer look at the Eisenman 2012 study that Chris Reynolds mentioned in the previous PIOMAS thread.
http://eisenman.ucsd.edu/eisenman_cv.pdf

This paper is pretty hard-core scientific, and very non-committal, but after close examination, I found that it contains a wealth of balanced reasoning and analyses on how much each of the climate variables affects the short and medium fate of Arctic sea ice.

Specifically, I found figure 9 in the paper illuminating.
For starters, it shows the default (best current estimate) state of the current perennial ice covered Arctic as green dots, in a large number of plots of variables against external climate forcing (such as from GHGs).

Note that in these plots, if GHG forcing increases, these green dots will move upward in these graphs. Note also that if the default setting of these parameters does not change much, this will lead to a bi-stable state. So these plots suggest that we are currently very close to a seasonally ice free Arctic, but that this state is bi-stable, which means that at some point it will flip through to an annually ice free state.

That would NOT be a good prospect, since it will change the Arctic and thus weather in the Northern Hemisphere completely and virtually irreversible. A true 'tipping point' so to say.

So, the question is, did Eisenman choose these default parameters correctly, and if he did not, how much did he have to be wrong to get into a state that is less shocking, such as where perennial ice cover persists, or a seasonally ice cover is stable.

This is where I analyzed the 'default' parameter settings (the green dots in figure 9) defined in Table 1.
In general, I found these parameters to be reasonably chosen, and consistent with observations over the past 3 decades.

Now the scary part is that any of the plots in figure 9 show that ANY of these parameters would have to change quite significantly before the Arctic would end up in a stable 'seasonally ice free' state.

For example, the albedo change from thick to thin ice (0.43) as well as from thin ice to open water (0.08) seem consistent with the analysis Perovich & Polashenski, 2012 mentioned (again by Chris Reynolds) above, and figure 9G and 9H suggest that these values would need to change quite significantly to get out of the bi-stable state.

Also, the Planck feedback 1/B (climate sensitivity) Eisenman chose as 2.2 (1/0.45). This number seems consistent with
observation of NCEP/NCAR surface temp changes versus TOA LW radiation (as we discussed in the previous PIOMAS thread).
What is more shocking is that in order to get to a stable 'seasonally ice free' Arctic, the Planck feedback 1/B would have to change to at less than 1, which means it would have to start to behave as a black-body (or we would need to accept the deniers rhetoric of a Lindzen-type feedback system with climate sensitivity less than 1, which we all know is fundamentally flawed :o).

Another parameter in Eisenman 2012 is Fb, which is ocean heat flux. Here, Eisenman chose 0, but for sure that is an underestimate. In fact, there are many papers discussing the increase in ocean heat flux under Arctic sea ice, due to warmer Atlantic water influx. Polyakov et al 2010 even concludes that 1/3rd of Arctic ice volume loss is caused by increased ocean heat flux over the past 3 decades. So it surely is not 0, and thus figure 9C (Fb dependence) suggests that we may actually already be in that bi-stable state that we all fear...

There are some suggestions in Eisenman 2012 that argue for a stable seasonally ice free Arctic. One of them is that models that show ice thinning due to enhanced ice export, and consequently cooler ocean surface temperatures tend to end up with more stable seasonally ice free states. Still, this may be the case around Antarctica, but the ice export in the Arctic (confined through the Fram strait corridor) is not significantly increasing and ocean surface temperatures in the Arctic are certainly high.

So, it seems to me that Eisenman 2012 makes a very strong case that the Arctic will soon enter or already is in a bi-stable state, where it could quite easily flip through to a year-around ice free state, if GHG forcing only marginally increases.

Now I'm getting really concerned.

Rob Dekker

OK. Sorry guys. That was Eisenman's CV. Here is the paper itself :
http://eisenman.ucsd.edu/reprints/Eisenman-2012.pdf

Arcticio

Wipneus, your map is definitely a highlight this winter. Could you provide an error margin for 2018? Is it more than one year?

Wipneus

Arcticio:

PIOMAS has uncertainty of about 1 [1000 km3]
(1.35 absolute, 0.75 for anomaly). I don't see how that would translate to much less than 2 years.

Only if I could make a case that the calculated "extents" match independent data (like NSIDC) extremely well, then I could lower that uncertainty.

Note that I indicated the extent between double quotes: it is an extent-like measure but I am not sure yet if it is comparable with IJIS, NSIDC or even CT-area figures. This is something I still intend to look into.
I don't use a cutoff (like 15% as extent is usually defined). Introducing one may give an earlier date.

All,

Using the exponential fits per grid point, I calculated volume. All grid points where considered, not just the points that had ice in 2011. Compare with the usual non-gridded exponential and gompertz fits here:
https://sites.google.com/site/arctischepinguin/home/piomas/grf/pgd-volsep1.png

For the years 1978-2012, the fits are comparable (but it is nice to see that the 2012 gridded exponential prediction is spot on). Extrapolating over the coming years, the gridded exponential is between exponential and gompertz fit. A "virtual ice free" state is reached in 2017, about a year before the gompertz extrapolation.

Here are the figures:

2011 4.0307256
2012 3.1846369
2013 2.4332672
2014 1.7721108
2015 1.2252544
2016 0.7878664
2017 0.4883707
2018 0.3317498
2019 0.2660769

Jim Williams

Thanks with the help on that paper Rob Dekker. It was giving me headaches, but I kind of suspected that was what it was saying. It's not to helpful about timelines, but I'd say it supports my belief that an ice free Summer will lead shortly to an ice free Arctic.

crandles

I think it will happen a lot faster than the gridded exponential. So you have put me right off the gompertz except as an allowance for possible negative feedback items to put an upper limit on the date of ice free.

Really great to see the volume plot Wipneus. I hate to suggest extra workload when you are doing such great stuff. However, if you are interested in other similar/related suggestions of what to do: I would like to see map of speed of thickness decline in April over the next three or four years following a gridded exponential fit of April thicknesses. I would also like to see the volume extrapolation at maximum over next 4 years.

I expect to see volume rapidly falling to 19K km^3 and when that happens I believe virtually all the ice will melt that year.

(Melt=22.8-.213*Max Vol formula suggests a melt figure of 18.8K Km^3 when MaxVol=18.8K Km^3. I don't rule out it happening at higher max vol if the sensitivity of open ocean area increases more rapidly with thinner ice than it has in the past which seems quite likely.)

Apocalypse4Real

Thanks again for the amaazing work on the PIOMAS and potential for an ice free Arctic. The UK Met has just released the new sea ice model outout beginning January 16.

Three facts are readily apparent:

1) The "hole" in the NCOF ice thickness model is gone.

2) The amount of thick MYI is scarily absent. Awe and amazement were my first reactions. Werther, you will appreciate this.

3) The imagery is stunning - both in visual detail - but more than that - the changes in sea ice thickness from the LIM model to to a CICE based forecast.

As much as a meter or more of current ice disappears from what they project is currently in the CAB and the Fram Strait chunk of MYI ice is visible in contrast to FYI flow.

I have placed the NCOF/UK Met and MMAB SSMIS concentration together for side-by side comparison.

https://sites.google.com/site/apocalypse4realseaice2013/home/sea-ice-concentration-and-thickness-comparison

Also, I have placed the NCOF/UK Met and HYCOM/CICE thickness maps together for comparative purposes.

https://sites.google.com/site/apocalypse4realseaice2013/arctic-sea-ice-thickness-2013

This is initial output. I plan to correspond with the folks at the UK Met this coming week on the change.

A4R

Wipneus
However, if you are interested in other similar/related suggestions of what to do: I would like to see map of speed of thickness decline in April over the next three or four years following a gridded exponential fit of April thicknesses. I would also like to see the volume extrapolation at maximum over next 4 years.

By all means do suggestions. Without someone suggesting months ago to do exponential fits for the Arctic sub-regions, I might not have had the idea to do it. First I am exploring the method, to get a grip of its strengths and weaknesses. Actually I am amazed at the results so far.

And yes, I plan to look at the other months too.
Further it should now be possible to extend the Arctic Ice thickness movie:
https://www.youtube.com/watch?feature=player_detailpage&v=G1TLzgSlGtQ

And gridded data comes only as monthly data, do you really require the maximum daily value?


Bob Wallace

I'd like to see an April-only and a September-only version.

Going back to Rob's question

- How come you guys predicted this while IPCC models projected this state 40 years later ?

I'd say it's because people like Wipineus started paying attention to the third dimension of the sea ice and not simply its surface measurements.

crandles

Thanks Wipneus.

April would be fine. (I can soon work out the daily maximum is more than April average by about 0.12 K Km^3 with this has no clear trend over time. That is a simple enough adjustment and I don't trust my function to that level of accuracy anyway.)

Chris Reynolds

Rob,

Interesting observations regards figure 9. I've just re-read the paper, I understand a lot of it, but not enough to reproduce its calculations. Which is where I was last time I read it.

Regards Perovich & Polashenski and the Eisenman paper. The albedo change implied in Eisenman is only to do with sea ice / ocean albedo changes. 'Delta-Alpha (DA)' as in equation 11, and end of sect 2.1 relates to the shift from sea ice to ocean. With ref to fig 9g - DA is albedoICE - albedoOCEAN implying an increase in DA for Perovich & Polashenski, so increasing DA would takes us further towards the dual state where perennial ice (as present) and perennial ice free co-exist, and further from seasonally ice free as a stable state.

The figure showing critical slowing at a bifurcation reminded me of the recent work of Livina and Lenton, I think you'll find it interesting. e.g. "Early warning of climate tipping points from critical slowing down: comparing methods to improve robustness" Lenton et al, 2012. Link. I say Livina and Lenton because they've done quite a few recent papers together on the issue of early warning of bifurcations.

Before my illness last year I was pondering trying their method on our sea ice data. But I never got round to figuring out how exactly to implement the procedure around equations 2.1 and 2.2. I also have concerns that what is happening now may be too fast. They have already published research arguing that the 2007 event shows bifurcatory behaviour, pdf, when I read that last year I thought similar reasoning would point to 2010 being such an event.

Chris Reynolds

Oops - should have added - Perovich & Polashenski is about changes to the albedo of sea ice itself.

Twemoran

The Eisenman paper is going to take some time, but assuming Rob's interpretation to be correct it seems a virtual certainty that we'll make a rapid transition from seasonally ice free to perennially ice free.

At present we're melting & freezing ~ 18.6K Km3 of ice on an annual basis. The energy diverted during melt season, then released during fall and winter cools Arctic summers and warms Arctic winters.

If we're looking at a scenario where latent heat of fusion is taken out of the equation & where winter Arctic temps still remain >0 doesn't this imply summer temperatures in the NH that are far above even the most extreme projections?

Terry

SATire

Rob is surely right - The Eisenman paper clearly describes the possibility for all year ice-free arctis. But it is of course very shy about when and concrete parameters...

SATire

... but hey - it is 1D and without that usual Monte-Carlo-stuff. One really can work with it.

Ron Mignery

Terry

Why would NH temps be so much higher? Heat radiates to space everywhere and every season and 18.6 Km3 of melting potential spread over half the globe might not be all that significant temperature-wise.

What I fear more than higher temps is perennial summer drought over all the continents as the driver of the westerlies, the temp delta between the Arctic and the tropics, is diminished.

Donald

This is just an aide for those who have not already laid out the Piomas data and done their own calculations --

Arctic Sea Ice Volume by PIOMAS
Year ...... Avg ...... Max ...... Min ...... Max Melt

2003 18.97 27.32 10.24 17.079
2004 18.46 25.81 9.88 15.930
2005 17.88 26.18 9.16 17.022
2006 17.22 25.19 8.99 16.198
2007 15.48 23.87 6.46 17.407
2008 16.58 25.16 7.07 18.087
2009 16.12 25.08 6.89 18.189
2010 14.03 23.40 4.43 18.974
2011 13.18 21.96 4.02 17.944
2012 12.68 21.92 3.26 18.662

Donald

My apologies for the formatting; you can copy and paste the table somewhere more useful.

Werther

Evening everybody, A4R,

If thie is what you are referring to:
 photo NCOF17January2013klein_zps247a5938.jpg

It looks pathetic...

I have to delay an opinion...while it is always lingering in my mind that even PIOMAS might be too optimistic.

Meanwhile, I've been busy on the 2009 Greenland ice/snow boundary. Filled up 10.000 km now, hell of a job.
Also had a look at 1985 compared to 2013. On Sudden Strat Warming and NCEP/NCAR composites (50/200/500 Mb Geo, SLP, 1000Mb temp etc).

There are similarities in geographic distribution ASO. The striking part may be quite simple: it's AGW, stupid...!
Obviously, 1000 Mb temps in the period 1/12 to 17/01 are much higher now. They're up to +12 dC above the climo in the central Arctic and the Barentsz-Kara region.
And compare them on CT: see FYS how sea ice bulges around Newfoundland and fills the St.Lawrence Gulf, the East Sea in Europe south of Stockholm and connects all Danish islands in the Sont-Kattegat region.

True, 1985 also showed warm anomalies in the Svalbard-Frantsa Yosefa region. The SSW pattern is the same. It is AGW enhancing it's impact.

Werther

This might be interesting on the study of SSW's:

http://journals.ametsoc.org/doi/pdf/10.1175/1520-0442%282004%29017%3C2584%3ATLCOTN%3E2.0.CO%3B2

If the present high in the Chukchi/ESAS Sea is in any way related to this SSW cycle, we're witnesseing quite a heavy one...

Bob Wallace

Ron - add in the loss of albedo - less energy reflected back into space, more sunlight converted into heat.

Also the potential for additional heat being carried forward from year to year as the Arctic Ocean stores heat?

R. Gates

Werther,

Certainly the general high pressure anomaly over the extreme NH right now is related to the SSW event that commenced in late December and continues. We see this high pressure anomaly reflected in this graphic:

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_HGT_ANOM_ALL_NH_2013.gif

With the break up of the Arctic Vortex caused by the SSW, we saw a reversal of winds and high pressure generally from north of 80 degrees with the high pressure anomaly increasing with increasing height in the stratosphere.

What I am watching with most interest now is the degree to which the vortex will reform for the remainder of the winter into February and March, or whether we might get even another smaller SSW event to occur. The nature of the reformation of the vortex will have huge implications for determining the peak NH sea ice extent this winter as well as how strongly and rapidly the melt season commences as these are so closely tied to winds and the vortex.

Werther

 photo Thasiersnowscape20012013_zps40d01b30.jpg
Just been out with my dog, Thasier.
A dark night, snow continuum Norilsk-Atlantic seaboard in Eurasia.
Maybe some comfort for our Australian friends sweltering it out...
Can understand why people just don't get what's happening.

R. Gates

Just a point of reference related to my last comment. Here's a nice view of what the polar vortex did last winter after a small SSW event in mid-January:

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_UGRD_MEAN_ALL_NH_2012.gif

The vortex (seen as red, orange, and yellow shaded areas in the graphic) broke down slightly during the 2-week period of the minor SSW in January 2012. Then we see the vortex reform for the remainder of the winter until it broke down for the spring/summer Arctic season. This year the vortex has already broken down much more severely and to greater depths in the stratosphere and upper troposphere.

In 2012, the vortex broke down for the season just about the same time as the peak in the Arctic sea ice extent. If the vortex broke down earlier for the season, or was weaker for much of February and March, this would have implications for the peak sea ice extent.

Werther

G'night R.Gates,

Appropriate... It reformed last year too, as Wayne may better describe than me, having witnessed late cold in the CAA-Baffin area.
It helped keeping +80dN temps low between day 80-120. Hope it does now too. Because 'warmth volume' has been even larger than last winter up to now (according to the DMI graph).

Werther

Nice dialogue... my rebound should have been 17 min earlier...sleep well my friends...

Kevin McKinney

"How come you guys predicted this while IPCC models projected this state 40 years later ?"

Bob, different methodologies get different results. The IPCC reports and other professional literature rely largely upon physical modeling, whereas the work Wipneus and others have done is based upon extrapolation alone.

Extrapolation is much simpler to do, but can go far astray because physical processes often result in non-linearities which change the trend. Physical modeling will (theoretically) match these changes, or can, at least. As a result, many scientists are more inclined to trust physical modeling than extrapolation of trends.

But in the present case, the physical models are apparently biassed low--a matter under intense investigation, and slowly being resolved.

Realclimate had a post on this:

http://www.realclimate.org/index.php/archives/2012/04/arctic-sea-ice-volume-piomas-prediction-and-the-perils-of-extrapolation/

Bob Wallace

From the Real Climate link -

" Clearly, linear, quadratic or exponential functions do not properly reflect the flattening of the trajectory in the next few decades seen for example in the CCSM4 (Fig 3). The characteristic flattening of this trajectory, at first order, arises from the fact that there is an increasingly negative (damping) feedback as the sea ice thins described by Bitz and Roe (2004) and Armour et al. (2011). The thick ice along the northern coast of Greenland is unusually persistent because there are on-shore winds that cause the ice to drift and pile-up there. "

An assumption that Bitz and Roe are correct when the data to date shows nothing to support a flatening of melt rate.

Earlier in this thread, we had a discussion about how the northern coast of Greenland and the CAA may well not be the safe haven assumed back in 2004.

Did Bitz and Roe include current knowledge of transport in their flattening model? That transport volume out the Fram is holding roughly constant via an increase in extent transported. Did they anticipate the openings into the CAA which let the ice escape? Did they allow for thinning ice to be shoved away from the shore where it is in the Fram exit path or did they consider it fast ice? Did they include the loss of snow cover on surrounding land and the resulting heat gains?

Then this bit...

"We believe that substantially skillful prediction can only be achieved with models, and therefore effort should be given to improving predictive modeling activities. The best role of observations in prediction is to improve, test, and initialize models.

But when will the Arctic be ice free then?

The answer will have to come from fully coupled climate models. Only they can account for the non-linear behavior of the trajectory of the sea ice evolution and put longer term changes in the context of expected natural variability."

I.e., the model we like says that the melt will be non-linear and years from now so we must look away from the actual data because it's looking damned linear and rapidly approaching zero.

Extrapolations are simple models. In theory a more complex model would do a better job of predicting future events, but at this point most of the complex models are failing.

We've spent a lot of energy on this site identifying accelerators and decelerators. We keep finding new factors which speed the melt and any forces which would slow the melt, dragging it out for several more years, just aren't making themselves known.

I think Schweiger, et al. got things turned around, just as I thought when I first read their post.

Data rules. Go with the data. If your model doesn't predict what has actually happened then keep working on your model. But don't insist that your model is what is real, especially if it's a flawed, non-predictive model.

(Actually I think what we will see is the opposite of a Gompertz curve. The year in which we reach zero for the first time will plot as a cliff when the ice simply collapses.)

Wipneus

One of the advantages of "R" that can turn into a disadvantage is that it is prefers to hold all object in memory. The virtual memory footprint of "R" on my computer is now over 13GB, no need to shut anything down as I have 16GB GB physical RAM.
That is not the case with my other project, investigation of the Sea Ice domain of the CMIP5 models. When processing those files, I regularly go beyond 30GB, forcing the OS to use large amounts of swap space and become too slow to use it for anything else than processing those files.

Anyway, I am slowly getting somewhere. Here is the state of Arctic Sea Ice in September 2046 according to a totally random picked model:

https://sites.google.com/site/arctischepinguin/home/cmip5/grf/NorESM1-ME_rcp85_r1i1p1_204609_NH.png

Steve Bloom

It'll be interesting to see the whole set, Werther. That one is entirely off the rails, and with RCP 8.5 to boot! Thanks for all your work on this.

Chris Reynolds

Bob Wallace,

Bitz & Roe area absolutely correct!

The paper concerned merely examines the time constants of first year (FYI) and multi year ice (MYI). It shows that MYI has a longer time constant than FYI. This is shown in PIOMAS where sub 2m thick ice (a proxy for FYI) volume is mainly unchanging, while the volume loss all comes from MYI. FYI can regrow in a winter, it takes four years to regrow MYI of four years old.

It is the Armour et al paper that extends Bitz & Roe to look at the implications on survival of the ice pack due to the transition to mainly FYI from mainly MYI.

Frankly I don't think anyone has the answer at present. Now that the pack has completed the transition from MYI to FYI, MYI is mainly gone after the 2010 event, we have to wait to see whether the short time constant of FYI retards the volume loss or whether the volume loss continues on trend. I think we'll see a rapid transition, but cannot make a water-tight argument that we won't!

Armour et al, 2011, "Controls on Arctic sea ice from first-year and multi-year ice survivability" PDF.

Bitz & Roe, 2004, "A Mechanism for the High Rate of Sea Ice Thinning in the Arctic Ocean." PDF.

Jim Hunt

Typepad seems to have eaten one of my posts. It was there, on my screen at least, but now it isn't! I know others have suffered a similar fate in the past. Is there any rhyme or reason to it?

The first bit was to thank Chris for those PDF links. Let's see if that message gets through, at least.

Jim Hunt

The balance has gone missing again. My apologies in advance if this results in multiple posts, but I continued....

According to Schweiger et. al.

"Fully-coupled models have biases in the mean wind field over the Arctic which may drive the sea ice into the wrong places, yielding unrealistic patterns of sea ice thickness."

According to Bitz & Roe

"One thing we know for certain is that the trends in the surface winds are much weaker in most CMIP models compared to recent observed trends"

For one recent example of some anomalous winds driving the sea ice into the wrong places see for example Weather Underground's record of the weather around the northern coast of Greenland last November

Jim Hunt

That time I got presented with a Captcha. Finally a pretty picture...

That resulted in this big hole in the MYI piled up against said coast:

It seems that in this day and age the MYI along the northern coast of Greenland is unusually non-persistent!

As you say, I don't think anyone has the answer either, but it certainly looks as though the complex models still aren't keeping up with the real world, let alone the not so complex politicians.

crandles

I think Bitz and Roe are right about

"The growth–thickness relationship is stabilizing and hence can be reckoned as a negative feedback."

However,
"The feedback is stronger for thinner ice, which is known to adjust more quickly to perturbations than thicker ice. In addition, thinner ice need not thin much to increase its growth rate a great deal, thereby establishing a new equilibrium with relatively little change in thickness."

is at best out of date and possibly misleading.

I think that although the feedback is stronger for thin ice than for thicker ice, winter is long so despite the feedback being weaker with thicker ice there is still long enough for much of the area to get close to thermal maximum thickness. So the extra strength of the feedback really doesn't do much. Also the effect of the negative feedback is limited: If the extra speed of growth means it catches up with previous years volume then the reason for the faster growth ceases. So there is no argument for more ice (unless there is less snow cover).

The final sentence I quoted

In addition, thinner ice need not thin much to increase its growth rate a great deal, thereby establishing a new equilibrium with relatively little change in thickness.

looks confused to me.

thinner ice need not thin much to increase the growth rate a great deal is true about perturbations. However, perturbations do not establish a new equilibrium.

Therefore it is something else that causes a new equilibrium each winter. In 2004 maximum volume was 25.81 K Km^3. This year looks like it will be about 21 K Km^3 at maximum. Given that maximum volume only need to decrease to about 19K Km^3, we have moved 4.8/6.8 = 70% of the way towards a seasonally ice free arctic in 9 years. So the thinning that has occurred has moved us a substantial distance towards a seasonally ice free arctic so a conclusion that we won't get much thinning looks out of date and in need of revision at best.

Kevin McKinney

Bob, I'm not arguing the case--I don't know what will happen. (Though for the record, I suspect that extrapolation may win out over modeling on this one.)

But you asked about the difference, and now you know more about its basis.

crandles

Chris Reynolds re your sub 2m thick ice as a proxy for FYI volume.

I think that gives you a silly trend which is nothing like actual FYI/MYI volume. I would suggest using: MYI (inc 1st year) Volume = Last minimum volume - 50 km^3 per month since that minimum for ice export.

This gives April 2005 9.53, April 2013 2.91

So I estimate that 30.5% of MYI (including 1st year ice) at April 2005 still remains. Using sub 2m as a proxy, I think you will get a completely different answer.

I think there is still a fair bit more albedo of FYI effect to come. The 70:30 split seems quite co-incidentally??? the same as in my post about Bitz and Roe above.
That isn't good.

crandles

By MYI (inc 1st year) I really meant MYI (including 1 to 2 year ice).

(Sometimes the split is FYI, 1-2 year ice, MYI.)

Jim Hunt

"The state of Arctic Sea Ice in September 2046 according to a totally random picked model"

A most interesting picture Wipneus! Were you using a Mersenne Twister to pick your model by any chance?

I had toyed with the idea of asking for a set of CESM credentials myself, but they insist on asking for my "institution", and I don't possess one :-(

Does the code for your selected model by any chance allow for farming out all that number crunching to other cores around the planet?

Wipneus

Jim,

No, I used the last model when alphabetically sorted by name, experiment and run.

Data output from the CMIP5 effort is available. I went to the ESGF site http://pcmdi9.llnl.gov/esgf-web-fe/ and followed the instructions there. I cannot recall "institution", unless perhaps you stumble on data that needs a commercial license. Ice thickness and concentration is all that I have downloaded (about 300GB of it), but there is plenty of other variables as well.

So I did not run models but went to analyse the output of these. Interested in:
- how do they underestimate ice decline, which regions etc;
- how about volume;
- how about Antarctic Ice;
- any models that predict decline in Arctic and growth of Antarctic Ice;

Jim Hunt

My mistake Wipneus.

I was getting over excited at the thought of "amateurs" being able to generate their own numbers by running their own climate models on distributed commodity hardware.

CESM are apparently happy to let you download the source code for their climate model, as long as you tell them the "institution" that you work for. Unfortunately I work from home!

Some freely downloadable papers on the Norwegian variant are available here.

crandles

>"I was getting over excited at the thought of "amateurs" being able to generate their own numbers by running their own climate models on distributed commodity hardware."

There is climateprediction.net Hadcm3 on PC/Mac/Linux but you get the runs the climate scientists headed by Myles Allen want you to run not what you want to run. You can keep the numbers generated and view them.

How close to seasonally ice free do we have to get before there is some pressure on the scientists to attempt to model what sort of climate we will get?

How is it best modelled? Can a run just be modified to change the volume at maximum to a little less than usually melts during a season? Might that make the model perform weidly unless further changes are made like to water temperatures?

Even if modellers prefer to believe their models rather than reality, surely there is enough risk that maximum volume might fall to 19 K Km^3 that the modelling of what happens to climate should be a priority? Even if modellers don't think it will happen within a decade, surely it is worth looking at likely effects when it does happen to allow some planning time.

Or perhaps it has already been done and there is no sign of any catastrophe?

If it hasn't happened, how would someone try to put pressure on funding bodies? / government? to try to encourage them to ensure such work was funded and done?

Bob Wallace

Yes Chris, it was Armour, et al. who pushed the idea that the last ice would linger and not Bitz and Roe. I made a bad assumption from the Real Climate article.

From Armour, et al.

"If the memory time scale and mean state sensitivity of Arctic sea ice decrease suciently(sic)quickly under a warming climate, a slowing in the rate of area and volume loss could occur.

This is consistent with the characteristic trajectory of September sea ice area decline in twenty- rst(sic)century simulations where the rate of change of Arctic sea ice area decreases late in the simulation despite a continued increase in climate forcing (e.g., Fig. 6)."

It seems that the "could" has transformed itself into "will" for some people. Let me recopy this bit which, IMO, is the important criticism of the RC paper....

"We believe that substantially skillful prediction can only be achieved with models, and therefore effort should be given to improving predictive modeling activities. The best role of observations in prediction is to improve, test, and initialize models.

But when will the Arctic be ice free then?

The answer will have to come from fully coupled climate models. Only they can account for the non-linear behavior of the trajectory of the sea ice evolution and put longer term changes in the context of expected natural variability."

When one lets their expectations supersede the facts then they are asking for trouble.

Chris Reynolds

Crandles,

2m is the thermodynamic maximum for ice growth. As you say, and as PIOMAS indicates, this is indeed typical of the maximum thickness gained during the winter from open water. i.e. the winter is long enough and cold enough to grow ice 2m thick from open water. Furthermore the use of 2m thick is commonly used as a rough proxy to divide between MYI and FYI. I have used 2m in summer as my proxy. Were I using it in winter I'd say 2.5m, as most of that ice from 2 to 2.5m is the upper tail of a distribution centred on 1.75m. I have been loose in my language. The survival of over 3k km^3 per year implies that amount of second year ice - a better term would be young and old ice, not FYI and MYI.

I have been repeatedly clear that what PIOMAS shows is insufficient thick MYI to bias the reported thickness of grid boxes to much over 2m in summer. In this sense 2010 represents a stark dividing line between the pre-2010, where there were significant numbers of grid boxes reporting over 2m thick at minimum to post 2010 when there were not. In view of this is it then just a coincidence that the seasonal cycle of PIOMAS changes after 2010?

I agree that there is a residual amount of MYI left in the pack, but I still see 2010 as the end of it being the dominant element, and the start of a largely FYI pack.

Regards Bitz & Roe. Again PIOMAS is not the only source showing a preferential thinning of thick (MYI) ice, both aircraft flights and DRA submarine data show this.

The faster growth issue, and rapid response to small perturbations will not change, unless the winter boundary conditions change, i.e. winter gets significantly warmer. The argument isn't one for more ice - just a quick recovery to winter equilibrium conditions when perturbed (by a winter or summer warming event).

I agree with your calculation. However this change was happening over a period when MYI (ice over 2m) was being lost. If we follow your argument that there is still a substantial amount of MYI, and this may be the case given that PIOMAS only tells us the average thickness of each grid box. Then this doesn't make Bitz and Roe out of date, it means that their 'time hasn't yet come'.

A consequence of Bitz and Roe is the memory of old ice (long time constant stores memory), and lack of memory of young ice (short annual scale time constant precludes memory of past perturbation). Therefore the volume loss we're still seeing may merely be the further loss of MYI, and I may have jumped the gun in concluding its removal largely complete. Indeed in March there is a large proportion of ice between 2 and 3m, but most of this is only the upper tail of a distribution peak centred on 1.75m thick.

But this would be a continuation of the past process. As the transition to an even larger fraction of FYI proceeds there will be further gains due to albedo change. But bear in mind that the change in volume anomalies since 2010 is concentrated as a drop from around 20/4 to 29/6, after which anomalies actually increase. It would take a massive increase in rate of loss over that period to take out the remaining 3.26k km^3. And knock on effects into the winter cannot be relied upon given the fast rate of growth up to 9M km^2 in area which is proportionate to the area at minimum.

Therefore if what is going on right now is the continuing removal of MYI, then the conclusion I draw is that the volume loss rate is likely to abate and a longer tail will emerge. But I really think that MYI is largely gone and that we're already at a mainly FYI pack - that the volume loss continues implies a fast demise to the pack.

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