Arctic Ice Discussion (The Melt)

[4wd]

Wasn't that 2010?

There has been some increase in multi-year ice, I don't see any need to pretend otherwise.

[songster]

Wasn't that 2010?

There has been some increase in multi-year ice, I don't see any need to pretend otherwise.

http://nsidc.org/arcticseaicenews/files/2012/04/Figure5.png

Multi-year ice (defined as 2+ year ice) is down on last year, as is perennial ice (all >1 year). There is however an increase in one specific cohort of multi-year ice, namely 3-4 year ice. This cohort is expected to be larger because of the temporary recovery in minimum extent in the summer of 2009. Ice that formed in winter 2008, and which didn't melt out in summer 2009 due to the temporary recovery, is now ~3.5 years old. Similarly, you can see that last year there was a "bulge" in the 2-3 year cohort, and so on.

However, that's one cohort, and is only a small proportion of the total ice.

[Gray-Wolf]

Wasn't that 2010?

There has been some increase in multi-year ice, I don't see any need to pretend otherwise.

and, just for Four; in case he missed BFTP's post above his? (another 'Nelson moment'?)

and just in case he missed that;

EDIT: And this from yesterday;

http://lance-modis.e...232000.250m.jpg

not a lot of 'growing' apparent but plenty of 'spreading'?

Edited April 12, 2012 by Gray-Wolf

[4wd]

I was looking for that, because it shows some recovery in older ice as I said.

You can't produce more four or five year old ice in three years.

[BornFromTheVoid]

I was looking for that, because it shows some recovery in older ice as I said.

You can't produce more four or five year old ice in three years.

Eh, but you can. 3 year old ice lasts to become 4 year old ice, 4 year old ice lasts to become 5 year old ice, all of which can happen in a single year.

[songster]

I was looking for that, because it shows some recovery in older ice as I said.

You can't produce more four or five year old ice in three years.

Yes, but the point is the only "recovery" cohort is the ice that froze during 2008 winter (and is now ~3.5 years old).

There is less 1-2 year ice this year than last, therefore next year there will very likely be a reduction in 2-3 year ice

There is less 2-3 year ice this year than last, therefore next year there will very likely be a reduction in 3-4 year ice

Overall, MYI is going down, and you can't keep looking to that one good year for salvation since we already know that the "recovery" hasn't been sustained. For MYI to increase year on year, then the summer minimum has to also increase year on year, not just blip up and then back down again.

[Gray-Wolf]

I think you need look no further than the 'ice age plots' I posted earlier ( http://polarbear.col...edu/IceAge.html ) to see just how dramatically MYI has reduced? Are you telling me to take seriously someone looking at the above plots and persuading 'recovery' is occurring whilst we all can see the type of decimation that brought the MYI to this point??? Would anyone like to take a guess at the amounts of MYI we'd need to retain each year to enable us to return to the mix of ice types we had in the early 80's (just run the animation backward if you want to see what 'recovery' would look like and then look again at the past 5 years of the changing percentages of each ice type)

Edited April 12, 2012 by pottyprof
Any need to lower the tone?

[4wd]

You appear to be talking about complete recovery, I said 'some' recovery, this seems evident to me in the graph you posted - or if you want to be picky then the steep decline seems to have paused.

What is clear is that the wild predictions of of no summer ice by next year were unfounded.

Away from the pernicious doom, there seems to be plenty of thick ice above Greenland this winter, and an exceptional if not record amount of ice in Bering at the moment

[oldsnowywizard]

Not to throw a spanner here chaps but .. You are arguing over one chart from one source ... Is it accurate ? Is it checked? Where is the data from how is it collected ? It is from the Internet so it must be accurate right ? I thought the only really accurate ( apparently) source started collecting data from 2011 so how can anyone argue over inaccurate representation from the last 30 years as if it were gospel ? Only useful as a trend and asks questions about how thin rubbish Ice has still managed to survive to increase the 3 to 4 year or whichever one is correct ?? Is it bad up there ? Yes ... But it's not as bad as some would let us believe every year

[4wd]

Quick read for the hippies

http://www.theregister.co.uk/2012/04/11/bering_sea_ice_cover/

[BornFromTheVoid]

Quick read for the hippies

http://www.theregist..._sea_ice_cover/

And yet it still isn't enough to make the Arctic even reach the average mark. Suppose that might be due to the Barents sea being lowest on record during February, and most of the Atlantic sector remaining well below average. At least you've given up on quoting Joe B, whom I must say has been very quiet the last year...

Not to throw a spanner here chaps but .. You are arguing over one chart from one source ... Is it accurate ? Is it checked? Where is the data from how is it collected ? It is from the Internet so it must be accurate right ? I thought the only really accurate ( apparently) source started collecting data from 2011 so how can anyone argue over inaccurate representation from the last 30 years as if it were gospel ? Only useful as a trend and asks questions about how thin rubbish Ice has still managed to survive to increase the 3 to 4 year or whichever one is correct ?? Is it bad up there ? Yes ... But it's not as bad as some would let us believe every year

The data is checked against actual sea ice thickness in the field. The figures aren't simply plucked out of thin air.

Can you provide some data to show that things aren't as bad as we're being led to believe?

[BornFromTheVoid]

I made an animation using MODIS images of roughly the area shown in yellow on the CT concentration map below. It includes the Bering, Chukchi, Beaufort, East Siberian sea and some of the central Arctic. It follows on from the animation I posted a few weeks ago showing the sea ice breaking up and exiting the Arctic via the Bering strait.

[oldsnowywizard]

Correct me if I am wrong but actual and probably more accurate thickness measurements of the whole arctic are only available from 2011? Surely an previous measurements won't be as accurate or actual thickness will only be measured by field visits which won't take into account vast areas .. Or sub data ? Or old satellite data ... I can't therefore post any realistic and accurate comparison of thickness .. I am not suggesting that results are plucked from the air just merely suggesting that one source should not be taken as gospel as previous posts seem to imply.. As for the animations thanks for the work .. I seem to remember chuckchi losing ice quickly 6 years ago too... I am not ignoring what is going on but I'm also not joining the doom and gloom posters here.. Another record year could be on the cards but there are so many variables involved in ice loss and retention that tbh anything could happen ? Remember the comments from after 07...even I thought it would be a long slippery slope in 08 but it was not the case despite new dirty thin ice etc etc

[BornFromTheVoid]

Correct me if I am wrong but actual and probably more accurate thickness measurements of the whole arctic are only available from 2011? Surely an previous measurements won't be as accurate or actual thickness will only be measured by field visits which won't take into account vast areas .. Or sub data ? Or old satellite data ... I can't therefore post any realistic and accurate comparison of thickness .. I am not suggesting that results are plucked from the air just merely suggesting that one source should not be taken as gospel as previous posts seem to imply.. As for the animations thanks for the work .. I seem to remember chuckchi losing ice quickly 6 years ago too... I am not ignoring what is going on but I'm also not joining the doom and gloom posters here.. Another record year could be on the cards but there are so many variables involved in ice loss and retention that tbh anything could happen ? Remember the comments from after 07...even I thought it would be a long slippery slope in 08 but it was not the case despite new dirty thin ice etc etc

Sorry if I came across as a bit harsh in my reply. Only reading it now do I realise how it seems!

I presume you're taking about Cryosat? That has been having calibration issues so they've doing a lot of testing with it lately, only having managed patchy thickness data so far.

I posted this in the last Arctic sea ice thread about the PIOMAS data, but here it is anyway

PIOMAS has been extensively validated through comparisons with observations from US-Navy submarines, oceanographic moorings, and satellites. In addition model runs were performed in which model parameters and assimilation procedures were altered. From these validation studies we arrive at conservative estimates of the uncertainty in the trend of ± 1.0 10³ km³/decade. The uncertainty of the monthly averaged ice volume anomaly is estimated as ±0.75 10³km³. Total volume uncertainties are larger than those for the anomaly because model biases are removed when calculating the anomalies. The uncertainty for October total ice volume is estimated to be ±1.35 10³ km³ . Comparison of winter total volumes with other volume estimates need to account for the fact that the PIOMAS domain currently does not extend southward far enough to cover all areas that can have winter time ice cover. Areas in the Sea of Okhotsk and in the Gulf of St. Lawrence are partially excluded from the domain. Details on model validation can be found in Schweiger et al. 2011 and (here). Additional information on PIOMAS can be found (here)

From what I've read only a handful of scientists thought we'd be down to seasonal ice within a few years but it's easy to see how a dramatic claim like that would get more attention than the more conservative views.

We haven't had a melt season dipole set up as strong as 2007, but last year almost reached the 2007 extent with the weakest dipole since 2006. But then again if we manage to go back to the -ve Dipole pattern that had been present during the winter, then there's a chance we may end up with a much higher level of ice that recent years for a while.

[Gray-Wolf]

Our current , and forecast weather, is not helping keep the older ice in the Arctic Basin;

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicespddrf_nowcast_anim30d.gif

with so much attention seemingly focused on the thin FYI extention in the bering sea folk are missing the 'real drama'

[BornFromTheVoid]

Our current , and forecast weather, is not helping keep the older ice in the Arctic Basin;

http://www7320.nrlss...ast_anim30d.gif

with so much attention seemingly focused on the thin FYI extention in the bering sea folk are missing the 'real drama'

I would appear that at least some of the ice around the Beaufort and Chukchi seas, which many were hoping had thickened up from the winter wind pattern, has been exiting through the Bering Strait over the last few weeks too. The return of the more similar Dipole Anomaly pattern is something of a concern, even though at this time of year the correlation between a +ve DIpole and sea ice extent is actually positive ( as the ice is blown south, it's still cold enough for new fresh ice to form in its place, giving the extent a temporary boost).

April SLP Anomaly

Winter SLP Anomaly

[BornFromTheVoid]

The break up of the sea ice in the Beaufort sea has really accelerated the last 4 days. Compare the last animation I posted (Apr 5th-12th) to this one (12th-15th)

[Geordiesnow]

Arctic ice looking in good shape, could be a fairly high minimum this year.

It was the 9th lowest since official records began CC! Higher than recent years granted, but in the overall picture, its still below average.

[keithlucky]

[

It waquote name=Geordiesnow' timestamp='1334604745' post='2292309]s the 9th lowe

Edited April 16, 2012 by keithlucky

[BornFromTheVoid]

Not correct Some Asian glaciers 'putting on mass' (BBC)...

...Glaciers in Asian mountain range expanding (Radio New Zealand)

This thread is about "Arctic Sea Ice", not glacial ice Keith

[Gray-Wolf]

Arctic sea ice that is , IMHO , entering the second year with the 'new' mix of ice shaped by mass loss and the growing influence of wins/drift/currents on the placement of that ice.

When we call an 'ice free Arctic Ocean' you can already see where a great chunk of that 9.5% of residual ice will live. When you look at the Greenland North shore and the edge of the Canadian Archipelago you can already see this occurring.

The rest of the basin is now 'up for Grabs' since the 'babies arm' of ice, from Beaufort across to the East Siberian Sea ,has gone and is no longer Trapping the N.Beaufort side of things from having access to Fram, Again we will see the younger ice that makes up this years 'arm' gone by late July and ice truly at the mercy of wind and current.

Funny that Mr Serezze predicted that it'd take a few years for the Can. Archipelago to get rid of it's MY ice, seems we are now at that point with the channels only able to put on FY ice. Another area to watch once it starts to melt?

Edited April 17, 2012 by Gray-Wolf

[4wd]

Keep up the spin. In the real world the sea ice seems rather keen to not do the right thing so far.

Probably best concentrate on volume estimates for a while yet.

http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png

[BornFromTheVoid]

I wonder if your doing nothing but spinning for long enough do you start to think that its everyone and everything around you that's actually spinning and not yourself...

Anyway, sea ice extent and area doing quite well lately with both getting gradually closer to average as can be seen in the link 4wd posted and here

Sea ice concentrations continue increase and may soon move above average across the Kara Sea as the very cold air that has been in place there in recent weeks looks set to remain. ice in the Bering sea remains anomalously high, while the Sea of Okhotsk is plummeting, which should continue as mild southerlies take hold for the next week. Hudson Bay has recovered from the slight loss earlier in the month back to average.

Other than the Sea of Okhotsk, most of the Arctic sea ice areas remain in relatively cold air for the next 5 or 6 so the slow start to the melt season should continue.

[Geordiesnow]

Keep up the spin. In the real world the sea ice seems rather keen to not do the right thing so far.

Probably best concentrate on volume estimates for a while yet.

http://nsidc.org/dat..._timeseries.png

Oh but that has all changed somewhat and NSIDC is coming under quite a bit of flack for it from some quarters because of the changes they made and how it seemed to affect the ice extent graphs.

http://www.real-science.com/breaking-news-nsidc-gets-in-the-data-tampering-act

http://www.real-science.com/nsidc-part-2

If I'm reading what NSIDC statement correctly, it will now mean there will be a two day lag instead of the one, apparently this is so it can erase out the possible flucturations we see on the tip of the ice extent line. It would appear they have launched this now hence todays chart on their website is still showing the 16th April.

I am aware the links I posted are from folk who have a bias of sea ice recovery but the cynical people out there could say its fairly ironic they have changed this just as the extent was approching the norm, now its been changed to show it further away. I have to admit, I do sometimes get the impression from reading those articles from NSIDC that they do have a slight bias towards wanting the sea ice to melt completely because their scientists(amongst loads of others) are predicting that what would happen.

[BornFromTheVoid]

Oh but that has all changed somewhat and NSIDC is coming under quite a bit of flack for it from some quarters because of the changes they made and how it seemed to affect the ice extent graphs.

http://www.real-scie...a-tampering-act

http://www.real-scie...om/nsidc-part-2

If I'm reading what NSIDC statement correctly, it will now mean there will be a two day lag instead of the one, apparently this is so it can erase out the possible flucturations we see on the tip of the ice extent line. It would appear they have launched this now hence todays chart on their website is still showing the 16th April.

I am aware the links I posted are from folk who have a bias of sea ice recovery but the cynical people out there could say its fairly ironic they have changed this just as the extent was approching the norm, now its been changed to show it further away. I have to admit, I do sometimes get the impression from reading those articles from NSIDC that they do have a slight bias towards wanting the sea ice to melt completely because their scientists(amongst loads of others) are predicting that what would happen.

That really is awful timing by the NSIDC, really, really awful!

Hi Anthony,

Thanks for letting us know. I have a guess at what this might be.

We’re starting to make some changes to our processing to update/improve things, including some you’ve suggested. One thing that we’ve decided to do is to change the way we calculate our 5-day average values. We’ve been doing it as a centered average – i.e., a given day’s value in the plot is actually an average of that day + 2 days before and 2 days after. This caused an issue at the end point because we’d extrapolate to get a 5-day average on the last day, which resulted in wiggles at the end that.

We’re now changing it to be a trailing 5-day average, i.e., a given day’s value in the plot is the average of that day and the 4 preceding days. This will take out the wiggle in the end of the plot (or most of it – there may be some change as sometimes we don’t get complete data and need to interpolate, and later (a day or two) we do get the data and process it.

Perhaps I'm also misinterpreting the old and new method they're using for their graphs, but I think the old one used the day in question (e.g., the 16th), the two days before (14th & 15th) and the two days after (17th and 18th). Seeing as in this example they only would have data up to the 17th, the 18th would have to be extrapolated to have a 5 day average. This means when they get the actual extent data for the day they extrapolated, the graph would change based on how much of a difference there was, causing the end to "wobble" on a daily basis.

The new method will instead use the day in question (e.g., the 16th) and the 4 preceding days (12th, 13th, 14th, 15th) so they don't require any interpolation and the line on the graph will remain consistent.

The thing is, it will make the graph more accurate, as before they were essentially "making up" one of the days to use in the average, but now they will only be using actual extent data. Despite what Goddard says though, the daily extent figures won't change at all as the numerical data will remain the same, it was only the method of creating an average for the graphs that will change. Problem is, I'm sure many people won't bother to try and understand this difference because it's easier to just follow Goddard's example and simply shout conspiracy!

Saying that, the NSIDC should really have known better and kinda shot themselves in the foot with their handling of the changeover.

EDIT: Just mixed up interpolate and extrapolate above

Edited April 18, 2012 by BornFromTheVoid