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Neven

One reason for 2007 being lower than 2012 on the MASIE graph may be explained in this 2015 paper by Walt Meier et al.: How do sea-ice concentrations from operational data compare with passive microwave estimates? Implications for improved model evaluations and forecasting (PDF)

Due to GAC-2012 some ice wasn't picked up by JAXA and other SIE products, that was picked up by MASIE.

D

Hi Neven, you might be interested in this and the comments: http://euanmearns.com/will-the-ice-in-the-arctic-ocean-disappear/

Apparently ice won't melt as the world gets warmer ;)

D

The paper linked above gives some detail about why the MASIE data may be different from other measurement products based on different grid resolution and measurement methods.
But I think your 'weight loss' comparison is also a good metaphorical explanation of the situation.

I am reminded of that frequent 'sceptical' trope that there is now MORE ice forming every winter in the Arctic than ever before. Especially after years when the summer low has been a record.

RICK BAARTMAN

Good article.

But I always feel that the non-expert deniers or confusionists... whatever, are handled with kid gloves; too politely. Any 9-year period where clearly the year-to-year fluctuations are as large or larger than the distilled "trend", does NOT show a trend. The clutz says, well, the data is the data and he cannot help that it shows a decreasing trend. No. It shows no trend. Period. This is the same issue I had (even worse) with actual climate scientists taking seriously the so-called pause between 1997 and 2013. Tamino has analyzed this too. Fluctuation is too large to say there is a trend. One needs no sophisticated statistical analysis to see this. Look at the noise. Now look at how large you say the trend is. Not larger? No trend.

Kevin McKinney

I've got to take issue with your formulation, Rick, though the overall point is correct.

Stated the way you have done, there would be 'no trend' in the UAH temperature record, for instance: its calculated value is 0.11 C/decade, but if you look at the anomaly values for 1998 (0.42 C) and 1999 (-0.05 C), you will find a 'fluctuation' of 0.47 C, or more than four times the decadal trend. Yet as you know, the reported UAH is indeed robust and statistically significant.

Neven
Hi Neven, you might be interested in this and the comments:

Well, the Walsh and Chapman historical sea ice cover graph certainly isn't perfect, but I feel the writer of the piece goes about it the wrong way. He quotes a lot of old papers that are about Nordic seas (maybe the NIPCC report was a source of inspiration), and the graphs are all about different time frames, different months of the year (not entirely clear), different areas of the Nordic Seas, etc. It's a bit of a jumble, used to arrive at a pre-determined conclusion.

I believe there are a couple of posts on Diablobanquisa's blog that are much more worthwhile when it comes to this subject.

As for the comment section. If someone mentions Steven Goddard as a reliable source and nobody counters it, it's clear that both writer and commenters don't have a very broad grasp of the issue. And there's some other nonsense in there as well.

Neven

Things are getting more embarrassing over on the blog where the annual average nonsense is posted. It seems the comment section has been closed, and my final comment hasn't appeared in it (it seems "Tamino’s (Foster’s) attack dogs" have been posting too, but we'll have to take Ron Clutz' word for it). I'm fine with deleting or not posting my comments, but how about being transparent about that?

Anyway, here's my final comment (I copied it, because I had a feeling the blogger would pull this trick) before I react to the nonsense in the blog post's update:


Neven, why is it so important that the Arctic lose ice, this year, next year, whatever year? What would that prove?

It's not important that the Arctic loses sea ice. It's the potential consequences of Arctic sea ice loss that are important.

I am looking at all 12 months, not just September, taking the lead from scientists who say the winter is when long term changes appear.

I'm looking at all 12 months too. I'm just not lumping all of them together like you do. And the changes are visible during winter, just less pronounced, mostly because the Arctic Ocean is surrounded by land masses.

I won't respond further to you. Finally, as has been pointed out to you, MASIE is a reliable, valid dataset, preferred by some researchers.

As you very well know, MASIE is reliable and valid for a look at the ice on a given day or through the week. It isn't reliable and valid when comparing trends in sea ice over time or when consistency is important.

Either way, I've put up a blog post on the Arctic Sea Ice blog, discussing the large differences between MASIE and all other daily data sets, and also a bit why claiming recovery based on annual averages is silly and misleading. You should really stop doing this.

All the best for 2016.

Neven

And now some nonsense from the update:

Warmists fail to see that having two different tracking methods for a climate phenomenon is a good thing. With temperatures they favor the land surface record and abhor the satellite temps. With Sea Ice they like the satellite reports and abhor the navigational observations.

I don't abhor operational products (or navigational observations, as Ron Clutz calls it), I just don't think that they're reliable enough for interannual comparisons. That's what my whole blog post is about (see the quotes from the MASIE product and documentation pages), and Ron Clutz has been told this many times now, but he keeps using MASIE for his interannual comparisons. First I thought it was because he was old and heavily biased, but given his behaviour I begin to suspect he does it to mislead people.

JAXA, DMI, NORSEX and NOAA (or NSIDC) are all using NASA data from passive microwave sensors on satellite to estimate ice extents.

Here again Ron Clutz shows his ignorance, and admits his previous ignorance about who is actually producing the Sea Ice Index (NSIDC, not NOAA).

JAXA puts out data from its own AMSR2 sensor on its own Shizuku (GCOM-W1) satellite.

DMI, and NORSEX too I believe, uses data (via OSI SAF)from the SSMIS sensor aboard the DSMP-F17 satellite, which is part of the US DoD's Defense Meteorological Satellite Program. The NSIDC (not NOAA) uses SSMIS data too for its Sea Ice Index.

Differences arise from differing algorithms at each center.

Different algorithms, different resolutions and different land masks. But all of this remains consistent from year to year, which is why all graphs in my blog post show the same curves and trend. MASIE, on the other hand, looks different, because it isn't consistent from year to year. And it doesn't need to be, because it isn't intended to be used for "comparing trends in sea ice over time or when consistency is important".

Ron Clutz knows this, but he persists in using MASIE data the way it isn't intended to be used. He is knowingly misleading his readers.

Neven

And if Ron Clutz (or his misled readers) don't believe me, they can read this explanation on WUWT by Walt Meier, which also tells us more about the subject of this blog post:

It [MASIE; N.] can provide better detail, particularly in some regions, e.g., the Northwest Passage.

However, it’s not as useful for looking at trends or year-to-year variations because it is produced from imagery of varying quantity and quality. So the analyses done in 2007 have different imagery sources than this year. And imagery varies even day to day. If skies are clear, MODIS can be used; if it’s cloudy then MODIS is not useful. Another thing is that the imagery is then manually analyzed by ice analysts, so there is some subjectivity in the analysis – it may depend on the amount of time an analyst has in a given day.

Our data is from passive microwave imagery. It is not affected by clouds, it obtains complete data every data (except when there may be a sensor issue), it has only consistent, automated processes. So we have much more confidence in comparing different days, years, etc. in our passive microwave data than is possible using MASIE.

Finally, MASIE’s mandate is to try to produce the best estimate they can of where there is any sea ice. So they may include even very low concentrations of ice <15%. In looking at visible imagery from MODIS, in the few cloud-free regions, there does appear to be some small concentration of ice where MASIE is mapping ice and our satellite data is not detecting ice. This is ice that is very sparse, likely quite thin. So it will probably melt out completely in the next week or two.

MASIE has tended to lag behind our data and then it catches up as the sparse ice that they map disappears. This year the difference between the two is a bit larger than we’ve seen in other years, because there is a larger area of sparse ice.

Now, if Ron Clutz is a man of honour, he will correct his blog posts and stop spreading his misleading, meaningless, MASIE-based annual average nonsense.

John Christensen

Great entry and great seeing you fighting for it Neven!

SnaggyD

MASIE, as I understand it, is a product aimed at providing digital data of the SeaIce extent as determined for use in Maritime Sector. This means that actual definition of what constitutes Sea Ice is different from that which is used in Arctic Research (afaik). For example the edge of the extent is an area that has enough Ice present that may pose a risk to people working at sea. The MASIE GIS layers do not contain any Sea Ice density data. Therefore when I use them I combined them with RTOFS Sea Ice model data to get and idea of what is going on. In short, MASIE should not be used to look at trends in Sea Ice as it is derived from data used for Sea/Arctic Safety purposes.

navegante

To be honest, Neven, none of these extent plots differ much. The anually averaged extent has not really changed in ten years.

However, the killer one is the volume variation. That is problematic evolution. And one not shown here which is the minimum extent in September and that goes on par with the loss of ice volume.
That alone is sufficient argument.

Tim

I think that the most useful plots are decadal; ten-year averaging eliminates most of the "weather" fluctuations are is more revealing as to "climate" trends. For example on the basis of these I would differ with navegante's assertion that "anually averaged extent has not really changed in ten years" :
Arctic Ice extent(IJIS2): http://i713.photobucket.com/albums/ww133/Sane_Person/Arctic%20Meltdown/Sea_Ice_Extent-IJIS2-Arctic_zpsp5xqgf4c.jpg
Arctic Ice Area(CT): http://i713.photobucket.com/albums/ww133/Sane_Person/Arctic%20Meltdown/Sea_Ice_Area-CT-Arctic_zpsobz6vtfn.jpg
Contrast the Antarctic: http://i713.photobucket.com/albums/ww133/Sane_Person/Arctic%20Meltdown/Sea_Ice_Area-CT-Antarctic_zpsxp5ognsg.jpg

The important information in all three of the above are the grey and black curves. I really think it would be more revealing for the NSIDC to use decadal averages rather than show the "standard deviations" getting ever larger. How much sense does it make when the "mean" is undergoing a systematic time-dependent decline to use all 36 years of the data to get standard deviations?

Tim

These plots take a while to load, if readers get impatient, I'll post lower-res pics!

Tim

Same plots, lower resolution:

Arctic Ice extent(IJIS2):
http://i713.photobucket.com/albums/ww133/Sane_Person/Arctic%20Meltdown/Sea_Ice_Extent-IJIS2-Arctic-lr_zpstzvapbsa.jpg
Arctic Ice Area(CT):
http://i713.photobucket.com/albums/ww133/Sane_Person/Arctic%20Meltdown/Sea_Ice_Area-CT-Arctic-lr_zpszmydhmjn.jpg
Antarctic (CT):
http://i713.photobucket.com/albums/ww133/Sane_Person/Arctic%20Meltdown/Sea_Ice_Area-CT-Antarctic-lr_zpsybrzcc4n.jpg

Kevin O'Neill

Ron Clutz obviously doesn't like people quoting facts at him with links to the actual MASIE FAQ page. My comment their (would have been comment #917) was never displayed.

2. When should I use MASIE and when should I use the Sea Ice Index?

Use the Sea Ice Index when comparing trends in sea ice over time or when consistency is important. Even then, the monthly, not the daily, Sea Ice Index views should be used to look at trends in sea ice.

Rob Dekker

Neven, I admire your restraint and patience with this guy Ron Clutz.

navegante

Good point Tim, and no doubt the negative trend decade to decade of average extent.

That guy selected the years (and the product in particular) very carefully to give a false impression. Cherry picking at its best. Probably the same kind of person that would go around saying that to extract any meaningful conclusion about climate you have to wait 100 years.

Truth is when you see the curves of ice extent evolution along the year,the last 10 years are pretty much bundled each on top of the others. 2012 had exceptional low but was way above average in March and April. 2013 had a very high max. And so. But the Winter ice is a blanket that is covering a very ugly reality. Denialists use that blanket to say "business as usual in the Arctic". But how to explain the albedo amplification, the dipole anomaly, and the loss of ice volume to someone that wants to stay on surface of things or that doesnt wanna listen. Ultimately I think myself, is it a battle worth to be fought?
Anyway the decade 2015 - 2025 is gonna be very different in terms of average, warming is unstoppable and Arctic amplification is well established.

Neven

Neven, I admire your restraint and patience with this guy Ron Clutz.

Well, on his avatar he seems friendly enough, so I thought I'd give him the benefit of the doubt. But he is knowingly lying and misleading.

I mean, here's the latest remark on his blog:

My focus is on the MASIE dataset and the story it has to tell, which I fear would be otherwise ignored.

MASIE has a day-to-day or week-to-week story to tell to people who depend on conservative estimates of where there is ice in places like the Northwest Passage or Svalbard, etc.

MASIE doesn't and cannot have a year-to-year story to tell, because of the subjective element (human analysts) and changing methods over time (see Walt Meier's explanation above).

Ron Clutz knows this by now, but he still wants to continue to tell this story, even though all MASIE documentation states that you can't do it like this. He is knowingly misleading people.

Clutz could use all the other graphs I've posted in this blog post (yes, I did all the work and had to explain to Clutz where all the data comes from) as they can be used for interannual, consistent comparisons. But of course, they paint an entirely different story. Never mind the fact that 'annual average' is a silly metric that doesn't tell the whole story.

I just hope that not too many people fall for this scam. It's a very serious issue that could cost a lot of money and lives in the not too distant future.

L. Hamilton

"I'm looking at all 12 months, not just September."

By coincidence I updated the 12-month cycle plot yesterday, following NSIDC publication of December 2015 monthly data. This shows the visible decline in both area and extent for every month of the year, 1979 to 2015.

http://img.photobucket.com/albums/v224/Chiloe/12_Climate/2015_Cycle_Arctic.png

Neven

Larry, it seems I can't copy that png. Could you send it to me (for the ASIG long-term graphs page)? Thanks.

Rob Dekker

Neven said

Ron Clutz knows this by now, but he still wants to continue to tell this story, even though all MASIE documentation states that you can't do it like this.

You can bring a horse to water, but you can't make it drink.

L. Hamilton

Sent a clean copy of the cycle plot to Neven, so hopefully that's forthcoming on the long-term graphs page. If anyone else wants the file, send me a note.
Larry

Bill Fothergill

As a complement (and as a compliment) to Larry's cycle graph, one can also look at the BIST diagrams available on the NSIDC website.

http://nsidc.org/data/bist/bist.pl?config=seaice_extent_trends

I usually have this set up with two columns, one each for the Arctic & Antarctic. With "extent trends" selected in each column, and 12 rows requested, this will then display the trend pattern for each month (i.e. Jan - Dec) in an individual row.

Bill Fothergill

In the OP, Neven makes reference to the article Tamino produced on the 28th September. In this article, he (Tamino) points out the pathetic mistake of comparing an annual average with a year-to-date average.

Now, anyone can make a silly, slap-forehead-with-palm-of-hand mistake - I should know, as I've made more than a few - but a reasonable person would acknowledge this when called upon to do so. An honest person, upon realising such an error, wouldn't even wait until they were called out on the matter. However, refusal to recognise when one has made a daft mistake smacks of either intransigent stupidity or deliberate deception.

The offending mistake was from an article written a couple of days earlier. A numerical comparison demonstrating the magnitude of the error is most illuminating, and I just happen to have a little y-t-d tracker running on the CT Arctic SIA numbers. The relevant figures are...

y-t-d average on 26th Sep 2015 .... 9.282 million sq kms
y-t-d average on 31st Dec 2015 .... 8.914 million sq kms

That's close to 370 thousand sq kms difference!

...

It is a relatively minor effect, but one must also remember that leap years are somewhat affected by this kind of problem. On a leap year, the annual average is based on 366 days, rather than the usual 365 days for other years.

For example, in 2012, the rolling 365-day average ending on 31st December, is about 4 thousand sq kms lower than the rolling 366-day average. In 2008, the difference was about 7 thousand sq kms.

Although relatively minor, if one is genuinely trying to compare like-with-like, this effect distances 2012 slightly further from other years.

viddaloo

On a sidenote, the Austrian NASI blog is celebrating the new year by throwing the baby out with the bathwater:

http://guymcpherson.com/forum/index.php?topic=3234.0

Leslie Graham

@Rob Dekker

"You can bring a horse to water, but you can't make it drink"

Alternatively;
"You can bring a denier to data, but you can't make it think"

Sorry - couldn't resist that one.

Rob Dekker

Thanks, Leslie, for making the point !

Bill Fothergill

" ... but you can't make it think"

Nice one, Leslie


And belated best wishes to all - hope you had a peaceful and prosperous (or even preposterous) perihelion.

navegante

Damn, Vid, that was a heck of a trojan troll. Still I give you the reason in the little trascendence on the sign of the graphs trends (except for the annually averaged volume which is the only metric that cant be masked by winter ice).

Another thing I wanted to point out is that ice extent started its "landslide" in 1999 after el Niño 1997/1998 if you carefully watch the NDSIC plots of each month, rather than just after the 2007 crash. That was 16 years ago! Bad prospect for the next post Niño 2015/16 years?

Andy Lee Robinson

And:

You can lead a denier to water, but you can't make it sink.

Neven

I made another effort to bring Ron Clutz to water, but I'm quite sure now he knows what he's doing. In the link to the 2012 WUWT blog post where Walt Meier explains how things work with operational products, etc, a commenter called Ron C posts several references to NIC documentation.

But anyway, he's deleting my comments again (and his own comments to wipe out traces of the fact, which is a cowardly act), so I'm just posting the comments here for reference:

Ron C: To repeat, Neven’s criticism of MASIE does not apply to the product output since 2006, which NSIDC said was reasonably consistent as their reason for releasing the dataset.

---

Neven: So, it seems there is something of a contradiction on that documentation page. On the one hand IMS (the operational analysis product on which MASIE is partly based) is described as “relatively/reasonably consistent”, as you quoted, Ron. On the other hand on the same page one can read statements such as:

MASIE may look like several other sea ice products distributed at NSIDC and elsewhere, but its source data and intended uses are different.

(…)

While operational analyses are usually the most accurate and timely representation of sea ice, they have errors and biases that change over time. If one is interested in long-term trends in sea ice or how it responds to changing climate forcing, generally, it is best not to use an operational product, but rather one that is consistently produced and retroactively quality controlled.

(…)

MASIE gives a quick picture of ice extent that is more accurate than the daily Sea Ice Index product and allows users to compare day-to-day changes in extent values. However, in general, it would not be appropriate to compare a recent MASIE extent value to one more than a few weeks old because the data sources and analysts NIC uses may have changed.

The best way to resolve this is to ask the NSIDC directly whether they think that MASIE can be used for interannual comparisons like you’re doing, Ron. I’d be willing to do this, but only on the condition that when the NSIDC says that MASIE is not the appropriate tool for interannual comparisons, you either stop doing so, or put up a clear caveat to inform people of the NSIDC’s stance on using MASIE for interannual comparisons.

Could you agree with that, Ron? If so, I’ll ask the NSIDC about this issue. Or you could do so yourself, of course.

---

Ron C: I will continue to follow the MASIE data coming out of the National Ice Center to see what it says about Arctic ice extents. No permission from Neven, Meier or anyone else is needed to analyze available data and draw conclusions. Nullius in verba.

---

[My next comment wasn't posted, but it was about how Ron C is not just following, but making his misleading chart and posting it without a caveat to inform his readers about what the NSIDC considers appropriate use of MASIE data; N.]

Neven: It seems my last comment hasn't shown up (there was no link, however). Could you please have a look to see if it got stuck somewhere, Ron?

---

Ron C: Neven, you keep saying the same thing. Enough already.

[Clutz then removed his own comment as well, and of course, my next comment hasn't shown up; N.]

---

Neven: I keep saying the same thing, because you keep refusing to acknowledge that you can't use MASIE the way you do and then claim a 'recovery' or a 'plateau', without letting your readers know that the NSIDC explicitly states in its MASIE documentation that interannual comparisons isn't an intended use. Either you stop doing it, or you put in the caveat. Anything else is misleading.

BTW, did you do anything to compensate missing dates? Or did you just divide a year's total by the total amount of days on which data was available?

Neven

So, that was the referencing, now for the interesting bit (although it is a bit of a nitpick):

BTW, did you do anything to compensate missing dates? Or did you just divide a year's total by the total amount of days on which data was available?

It turns out that MASIE data contains blanks on dates where numbers weren't reported. So, some years have 363 days, others 364, and 2009 has only 342 days. Clutz doesn't make the mistake of dividing the totals of all years by 365.

But if a year only has data for 342 days or 361 days (2014), the average is bound to change if you fill in the remaining 23 or 4 days (depending on the season). So, that's what I did. Here's an animation of the changes:

Only 2009's average changed markedly, from 10.82 to 10.95 million km2. The other changes are small. As for the trend line, R2 went down from 0.24 to 0.18, but I don't know enough about statistics to say if this really means anything.

Jim Hunt

I'm not quite sure why you expend so much energy on Mr. Clutz, who happily "moderates" out of existence comments on his blog he doesn't care for.

However when his grossly erroneous calculations for 2015 were first plastered across the Twittosphere by the usual suspects I did produce this by now fairly familiar looking graph:

which can be viewed in close proximity to the NSIDC version at:

http://GreatWhiteCon.info/resources/arctic-sea-ice-graphs/#MASIE

Can you spot the difference? Can Ron for that matter?

Neven
I'm not quite sure why you expend so much energy on Mr. Clutz

Because I'm annoyed, of course. Because he's the only source of misinformation wrt Arctic sea ice at the moment. And because the MASIE annual average graph differs so much from the annual average graphs of all other daily data products.

But as you repeat, an annual average doesn't convey the information shown in your minimum graph.

Jim Hunt

P.S. Re Ron et al. see also:

http://forum.arctic-sea-ice.net/index.php/topic,578.msg69254.html#msg69254

et seq.

Jim Hunt

He's the only source of misinformation wrt Arctic sea ice at the moment.

Actually some of the usual suspects are still up to their old tricks. Here's Rose channeling "Goddard" recently for example:

https://twitter.com/GreatWhiteCon/status/687919611539517440

Jim Hunt

Ron still hasn't published my constructive comment, and the GWPF still haven't fixed their misleading headlines, so I'm afraid that I have to admit that I got a trifle annoyed also. I'm taking your name in vain in my latest rant Neven. I hope that's OK with you?

"The Great Global Warming Policy Forum Con"

See also "Snow White's" Twitter feed:

https://twitter.com/GreatWhiteCon/status/695176179322642432

Neven

I'm not too vain for that, Jim. :-)

Neven

I mean I'm vain enough for that, Jim. ;-)

Jim Hunt

Not a lot of people know that Ron Clutz has yet to publish a single one of the numerous helpful comments I have left for him on his so called "Science Matters" blog, including one from yesterday.

Even fewer people know that I have just bumped into him somewhere else entirely:

http://archive.is/ICZib#selection-1031.0-1043.27

Bill Fothergill

@ Jim

Tee Hee

Jim Hunt

I'm having the proverbial whale of a time over there Bill. I can't type fast enough to keep up with them! By way of example see for instance:

https://archive.is/syz5k#selection-1151.0-1163.27

Bill Fothergill

Jim,

A few items you may care to point out to AndyG...

1)
The extent chart used in the First Assessment Report way back in 1990 was predicated upon 10% concentration. Therefore, all other things being equal, one would expect any anomaly swings to be greater than those seen using the current 15% threshold.

2)
On Fig 7.20 from the 1990 report, the peak of the smoothed anomaly gets down to about -0.35 or -0.4 million sq kms.

Using NSIDC figures, the average annual extent (not anomaly) for the period 1979-90 works out as 12.31 million sq kms. (That period starts from the deployment of Nimbus-7, with its SMMR instrument. The end date is set coincident with the end of the chart used in the 1st assessment.)

For the period 1991-2004, the average extent drops by a full 0.5 million sq kms to 11.81 million sq kms. (N.B. The half million drop is NOT a transient peak, but is the average across the entire period.)

For the period 2005-15, the annual average drops to 10.92 million sq kms.

In case your chum cannot work this out for himself, this means that, smoothed across the periods, there is about 1.4 million sq kms less ice during 2005-15 than there was during 1979-90.

I'll stress again that this is not a transient anomaly such as the dip at the LHS of Fig 7.20, its's effectively a horizontal line 1.4 million sq kms below the baseline.

3)
What possible bearing does ice extent during the early Holocene have upon today's situation? Does he think that, since wildfires have started naturally since the Great Oxygenation a couple of billion years ago, that the "supposed" crime of arson should be struck from the statute books?

Why stop at the Holocene? Let's jump back in time to before the Pleistocene Glaciation even began. What bearing does that have?

Jim Hunt

Thanks for all that most useful information. I wasn't previously aware of the 10% threshold. I wasn't an Arctic sea ice nutter in 1990!

However, for the moment at least, I'm waiting for him to reveal what it is he's so scared of. Pigs might fly?

Bill Fothergill

"Seekers of the truth" or "climate change sceptics", as they like to call themselves, often feel the need to refer to diagram 7.20(a) from the Working Group 1 contribution to the First Assessment Report dated way back in 1990.
https://www.ipcc.ch/ipccreports/far/wg_I/ipcc_far_wg_I_chapter_07.pdf

The reason for this love affair with that diagram is because it shows a slight downturn in Arctic Sea Ice. This graph containing the "unequivocal proof that AGW is a scam" runs from about 1973 to 1990, and does indeed have an early period which, when smoothed, (I think it's a 12 month rolling average) gets perhaps as low as 300k sq kms or so below the datum baseline.

What these "seekers of the truth" are strangely reticent to mention is the second of the paired graphs, namely 7.20(b). This pariah of the graph world relates to the Antarctic, and has the temerity to show an upward trend at the start of the measurement period. This reaches to about 1.3 million sq kms above the baseline.

I wonder why they're so silent about that one?

Anyway, for those interested in looking at the source data for these charts, it is available from the Naval Ice Centre, which is jointly run by NOAA, the US Navy and the US Coast Guard. (Obviously, the latter two organisations are well know for their subversive views, and long standing affiliation with those Commie bastards.)
http://www.natice.noaa.gov/products/ice_extent_graphs/arctic_weekly_ice_extent.html

Enjoy.

Jim Hunt

Thanks Bill. I once had a nice long chat with a senior officer from one of the subversive organisations to which you refer.

Here is a subversive recording of what he had to say for himself:

http://econnexus.org/the-economist-being-economical-with-the-truth-about-climate-change/

Diablobanquisa

Anyway, for those interested in looking at the source data for these charts, it is available from the Naval Ice Centre, which is jointly run by NOAA, the US Navy and the US Coast Guard. (Obviously, the latter two organisations are well know for their subversive views, and long standing affiliation with those Commie bastards.)
http://www.natice.noaa.gov/products/ice_extent_graphs/arctic_weekly_ice_extent.html

Enjoy.


NIC weekly sea ice charts from 1972 are available here: ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G02172/gifs_weekly/

https://nsidc.org/data/docs/noaa/g02172_nic_charts_climo_grid/

Bill Fothergill

@ Diablobanquisa

Due to the fact that I was away on a computer-free holiday late January to early February, I did not see Neven's reposting of your "September Arctic Sea Ice Extent: 1935-2014" article until my return.

You may therefore not have seen the very late comment I appended to the reposted article. (Or you may have already been aware of the data pertaining to Russian convoys during WWII.)

Diablobanquisa

I hadn't seen your comment, thank you very much, Bill.

I was aware of the convoys during WWII, although not with so much detail.

Cheers

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