2016 sea ice area and extent data

[Acts5v29]

Acts5v29, it is likely that we will get an "ice-free summer at the pole" way before we hit an "ice free Arctic" (less than 1 M km^2 left over in September).

Realize that there is a very big difference between the current (4 M km^2 minimum) and an ice free Arctic. There will be a host of other weather effects that will come into play before that.

That is why I carefully phrased it as ice-free summer **at the pole** (we have slush no more than 20 miles from there now) rather than one large Oceanic swimming pool.

In a way, it has become like sitting on a sofa watching lottery balls - transfixed on seeing the jackpot - but there are dynamics other than mere data which merit our attention now which might give us an insight into what lies further ahead then mid-September.

[CognitiveBias]

So about that ice free Arctic, Michael, can you please reference exactly where the IPCC changed their definition of ice-free to being 5years of minimums below 1m square km ?

I'd like to know who exactly initiated and executed that change in definition.

After all, it seems bizarre that IPCC would change this definition, when even a single year below 1 M km^2 is not supposed to happen for another 50 years at least, even according to the latest GCMs.

Rob,
  A single reference to 5-year 1M sq. km September Arctic ice can be found in IPCC's AR5 Synthesis Report.  See Figure 2.1(c)

http://ar5-syr.ipcc.ch/ipcc/ipcc/resources/pdf/IPCC_SynthesisReport.pdf

--CB

[charles_oil]

Found it - hidden in the notes on page (as the computer reads it) 75 of 167, page 59.  Where are we now on the actual graph which is too small to see really ?

[Tigertown]

NSIDC dropped their extent numbers back down a little. Interesting.

2016,    09,  01,      4.278,     
2016,    09,  02,      4.211,     
2016,    09,  03,      4.263,     
2016,    09,  04,      4.258,     
2016,    09,  05,      4.201,     

[Rob Dekker]

So about that ice free Arctic, Michael, can you please reference exactly where the IPCC changed their definition of ice-free to being 5years of minimums below 1m square km ?

I'd like to know who exactly initiated and executed that change in definition.

After all, it seems bizarre that IPCC would change this definition, when even a single year below 1 M km^2 is not supposed to happen for another 50 years at least, even according to the latest GCMs.

Rob,
  A single reference to 5-year 1M sq. km September Arctic ice can be found in IPCC's AR5 Synthesis Report.  See Figure 2.1(c)

http://ar5-syr.ipcc.ch/ipcc/ipcc/resources/pdf/IPCC_SynthesisReport.pdf

--CB

Thank you CognitiveBias, for digging up that reference !

I always wonder how these (climate) myths come about, and in this case I think it is clear :

Here is the exact caption to the sub panel (c) of figure 2.1 on page 59 of this report :

... (c) Change in Northern Hemisphere September sea-ice extent (5 year running mean). The dashed line represents nearly ice-free conditions (i.e., when September sea-ice extent is less than 10^6 km2 for at least five consecutive years)....

The fact that the claim in in parenthesis should have been a hint that it was intended as clarification of the previous sentences, NOT as a new definition.

The first sentence explicitly tells that the figure shows the 5 year running mean of sea ice extent as the red line.
The second sentence tells that the dashed line (at 1 M km^2) represents ice-free conditions.
The sentence in parenthesis then (over) explains that when the red line crosses the dashed line that sea ice extent has been below 1 M km^2 for 5 years.

So the IPCC did not (re)define the definition of what "ice-free Arctic" means.

They simply over-clarified what that figure 2.1, subpanel (c) on page 59 means, and by doing so opened up the text for mis-interpretation.

Now the followup question is : who first concluded that IPCC "redefined" what "ice-free" means ?

[budmantis]

Found it - hidden in the notes on page (as the computer reads it) 75 of 167, page 59.  Where are we now on the actual graph which is too small to see really ?

I would really be interested in what you found Charles_Oil. Your post seemed rather cryptic. Can you elaborate?

[Rob Dekker]

Re. Definition of "ice-free" Arctic in IPCC AR5 reports,
It is more serious than I suspected.

AR5's summary report here :
https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SummaryVolume_FINAL.pdf

quotes on page 92 :

A nearly ice-free Arctic Ocean (sea ice extent less than 10^6 km2 for at least five consecutive years) in September before mid-century is likely under RCP8.5

That is about as clear as it gets.
Somehow IPCC indeed has (re)defined "nearly ice-free Arctic Ocean" as "less than 1 M km^2 for at least five consecutive years".

I'm stunned.

Why and who did that ?

[oren]

Re. Definition of "ice-free" Arctic in IPCC AR5 reports,
It is more serious than I suspected.

AR5's summary report here :
https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SummaryVolume_FINAL.pdf

quotes on page 92 :

A nearly ice-free Arctic Ocean (sea ice extent less than 10^6 km2 for at least five consecutive years) in September before mid-century is likely under RCP8.5

That is about as clear as it gets.
Somehow IPCC indeed has (re)defined "nearly ice-free Arctic Ocean" as "less than 1 M km^2 for at least five consecutive years".

I'm stunned.

Why and who did that ?

At least the why is easy, to downplay a visible and quick consequence of AGW.

[abbottisgone]

Becoming worst (or better, depending of the person that is writing). Too early for conclusions, but impressive. 1st. lowest on record.

Does the wierd trajectory of 2012 in the early part of the year indicate a lot of trouble with the measuring process that year for some reason?

[charles_oil]

Sorry for being cryptic - I just meant that the graph is quite small - and an image rather than figures. It would be interesting to see where we are a couple of years on if the graph was available or reproduced and updated....  Though the report came out in 2015 I suspect the data was up to 2014 only.

[Rob Dekker]

Re. Definition of "ice-free" Arctic in IPCC AR5 reports,
It is more serious than I suspected.

AR5's summary report here :
https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SummaryVolume_FINAL.pdf

quotes on page 92 :

A nearly ice-free Arctic Ocean (sea ice extent less than 10^6 km2 for at least five consecutive years) in September before mid-century is likely under RCP8.5

That is about as clear as it gets.
Somehow IPCC indeed has (re)defined "nearly ice-free Arctic Ocean" as "less than 1 M km^2 for at least five consecutive years".

I'm stunned.

Why and who did that ?

At least the why is easy, to downplay a visible and quick consequence of AGW.

That is plausible, yet implies a motive.
Here are the editors of this most important report (Scientific Basis, for Policy Makers) :

Thomas F. Stocker : Working Group I Co-Chair
University of Bern

Dahe Qin : Working Group I Co-Chair
China Meteorological Administration

Gian-Kasper Plattner : Director of Science

Melinda M.B. Tignor : Director of Operations

Simon K. Allen : Senior Science Officer

Judith Boschung : Administrative Assistant

Alexander Nauels : Science Assistant

Yu Xia : Science Officer

Vincent Bex : IT Officer

Pauline M. Midgley : Head

Who has the motive to change this definition (which 'buys' at least 5 years) ?
Or may it be one of "The team of 209 Coordinating Lead Authors and Lead Authors plus 50 Review Editors " ?

Mmmm. this re-definition may be more 'anonymous' than anticipated...

[edit] However, to get a (re)definition like that pulled off in this main report likely requires sign-off at a very high level....

[Peter Ellis]

The motive seems quite clear to me - try to get people to pay attention to the 5-year mean rather than individual years.  The first individual year under 1 million will be definition be an outlier and is almost certain to be followed by a year above 1 million.  For something as important as this, there needs to be a definition where the deniers can't turn around 12 months later and pretend there's a recovery.

The "five consecutive years" seems to have spread by a comedy of errors.

First, there's a bungled attempt at clarification in the figure caption on page 21. The intent of the sentence is clear from the graph- it plots the 5-year mean and draws a dotted line to show where the 5-year mean falls below 1 million - but the caption erroneously says this means 5 consecutive years below 1 million.

That error then seems to have been propagated further down the document into a footnote on page 25 and a paragraph on page 88. This needn't have been any of the actual authors, it could even have been a copy editor inserting clarifications based on the earlier (erroneous) clarification in the figure caption.

Seeing this as a conspiracy is nuts.  You talk of "buying" 5 years.... for what purpose and to what effect?

[Rob Dekker]

The motive seems quite clear to me - try to get people to pay attention to the 5-year mean rather than individual years.  The first individual year under 1 million will be definition be an outlier and is almost certain to be followed by a year above 1 million.

Yet that year was clearly one that was "nearly ice free".

For something as important as this, there needs to be a definition where the deniers can't turn around 12 months later and pretend there's a recovery.

Deniers take every opportunity to turn a low year into a "recovery". With or without IPCC definition.

The "five consecutive years" seems to have spread by a comedy of errors.

First, there's a bungled attempt at clarification in the figure caption on page 21. The intent of the sentence is clear from the graph- it plots the 5-year mean and draws a dotted line to show where the 5-year mean falls below 1 million - but the caption erroneously says this means 5 consecutive years below 1 million.

That error then seems to have been propagated further down the document into a footnote on page 25 and a paragraph on page 88. This needn't have been any of the actual authors, it could even have been a copy editor inserting clarifications based on the earlier (erroneous) clarification in the figure caption.

Seeing this as a conspiracy is nuts. 

I did not mention anything about any "conspiracy".
But now that you mention it, it appears odd at least that the main editors failed to catch such a sequence of errors in the main report which brings a Scientific Basis to Policy Makers.
 

You talk of "buying" 5 years.... for what purpose and to what effect?

5 years is some $20 trillion in fossil fuel revenue.

[S.Pansa]

The changes made to the reports can be retraced here (under "Drafts and Review Materials").

I have done  only a quick search, so this is most probably not exact. But what I found was:
- The addition " for at least five consecutive years" first appears in the "approved Summary for Policymakers", p. 14
- It does not appear in the final draft (FD) of the "Summary for Policymakers".

- So something in between those two versions changed. Unfortunately I could not find any reasoning in the comments to the FD.

[Bill Fothergill]

The changes made to the reports can be retraced here (under "Drafts and Review Materials").

I have done  only a quick search, so this is most probably not exact...

Hats off to you for even trying to go down that forensic route.

I remember trying to do something similar with the WGII AR4 drafts in the wake of the Himalyan Glaciers nonsense. Boy was that depressing.

[S.Pansa]

...

Hats off to you for even trying to go down that forensic route.

I remember trying to do something similar with the WGII AR4 drafts in the wake of the Himalyan Glaciers nonsense. Boy was that depressing.

Thanks Bill! I agree it is a painful ride ... but sometimes I just can't help myself.  Oh dear

For what it is worth, I continued my inquiry and here is what I found:

- I searched the full AR5 WGI report for the phrase "five consecutive". The search came up with 4 hits, 2 in the SP (Summary for Policymakers), 2 in the TS (Technical summary). All 4 are linked to the definition of ice-free Arctic.
- Then I looked into the drafts of the TS. No sign of the phrase "five consecutive"   - no word in the comments.
- The only place where this changes are documented is the "List of Substantive Edits ", for instance p. 9 as "replace "(sea ice extent less than 10^6 km2)" by "(sea ice extent less than 10^6 km2 for at least five consecutive years)".
Interestingly enough there is no (scientific) reason given to why this change was made (Seems strange for the TS, that should be more "scientific" as the SP)

Summary: So for now it seems that the addendum to the ice-free definition "for at least five consecutive years" was first made in the "Approved Summary for Policymakers (IPCC-XXXVI/Doc.3)". Again no reason to why they did change it. For some reason, this definition made its way into the Technical Summary. Why remains a mystery - at least to me.

So while I generally agree with Peters sentiment this is starting to look a bit odd for a supposedly transparent report. At least I am not sure that the reason behind the change is purely scientific.
If I remember correctly, the Summary for Policymakers is the most political part of the report (as every UN-member state has to agree on the exact wording?). Now the addition to the ice-free definition, it appears, was introduced in exactly this political part. Later it was added to the more scientific TS, but without any explanation (by the looks of it).

And why "five consecutive years"? This is - at least to my understanding - a more rigid threshold as a five year running mean (a sequence of 0.9/1.5/0.9/0.5/0.8 would make the second but not the first). If it is true that in the SP all parties have to agree on every single word, a loose wording does not seem very likely ... Honi soit qui mal y pense

It would be really great if someone with more insight could clarify this for us.

[Archimid]

The first individual year under 1 million will be definition be an outlier and is almost certain to be followed by a year above 1 million

You can't say that with any sort of scientific certainty. The arctic has not been ice free for probably millions of years. What happens after the first ice free year is anyone guess. There is no way the IPCC can say that once the ice is gone it will grow back with any kind of scientific certainty. Extraordinary claims require extraordinary evidence. Since there is no data on an arctic ice free earth, then there simply can not be the extraordinary evidence required to make that claim.

Defining an ice free arctic as a 5 year average conveniently ignores the risks of the first ice free arctic. This gives politicians the room necesary to ignore the problem and "keep the economy going". Just like the fossil fuel interests want.

[Tigertown]

Looks like NSIDC SIE has about stalled out as well.

2016,    09,  05,      4.201
2016,    09,  06,      4.203

[BornFromTheVoid]

5 day NSIDC rolling average is still dropping, just about. However anything more the 4,211,000km2 tomorrow will result in the first 5 day average increase since May 16th.

2nd: 4.379
3rd: 4.322
4th: 4.280
5th: 4.242
6th: 4.227

[Lord M Vader]

Annoyingly close to 2007 number due to NSIDC, BFTV!

[BornFromTheVoid]

We might drop another bit in extent, but I'd say anything within 50k is essentially a tie.

[Rob Dekker]

...

Hats off to you for even trying to go down that forensic route.

I remember trying to do something similar with the WGII AR4 drafts in the wake of the Himalyan Glaciers nonsense. Boy was that depressing.

Thanks Bill! I agree it is a painful ride ... but sometimes I just can't help myself.  Oh dear

For what it is worth, I continued my inquiry and here is what I found:

- I searched the full AR5 WGI report for the phrase "five consecutive". The search came up with 4 hits, 2 in the SP (Summary for Policymakers), 2 in the TS (Technical summary). All 4 are linked to the definition of ice-free Arctic.
- Then I looked into the drafts of the TS. No sign of the phrase "five consecutive"   - no word in the comments.
- The only place where this changes are documented is the "List of Substantive Edits ", for instance p. 9 as "replace "(sea ice extent less than 10^6 km2)" by "(sea ice extent less than 10^6 km2 for at least five consecutive years)".
Interestingly enough there is no (scientific) reason given to why this change was made (Seems strange for the TS, that should be more "scientific" as the SP)

Summary: So for now it seems that the addendum to the ice-free definition "for at least five consecutive years" was first made in the "Approved Summary for Policymakers (IPCC-XXXVI/Doc.3)". Again no reason to why they did change it. For some reason, this definition made its way into the Technical Summary. Why remains a mystery - at least to me.

So while I generally agree with Peters sentiment this is starting to look a bit odd for a supposedly transparent report. At least I am not sure that the reason behind the change is purely scientific.
If I remember correctly, the Summary for Policymakers is the most political part of the report (as every UN-member state has to agree on the exact wording?). Now the addition to the ice-free definition, it appears, was introduced in exactly this political part. Later it was added to the more scientific TS, but without any explanation (by the looks of it).

And why "five consecutive years"? This is - at least to my understanding - a more rigid threshold as a five year running mean (a sequence of 0.9/1.5/0.9/0.5/0.8 would make the second but not the first). If it is true that in the SP all parties have to agree on every single word, a loose wording does not seem very likely ... Honi soit qui mal y pense

It would be really great if someone with more insight could clarify this for us.

S.Pansa, thank you for digging up the details on this.

From your work, it seems that the addition "for 5 consecutive years" was introduced between the "final draft for policy makers" (june 7, 2013) and the "approved Summary for Policymakers" (september 26, 2013).

And it seems that the addition "for 5 consecutive years" was inserted for political reasons, since it is decidedly NOT scientific. For example, the context in which it now stands is regarding climate simulations for RCP 8.5. As the "approved Summary for Policymakers notes :

Based on an assessment of the subset of models that most closely reproduce the
climatological mean state and 1979-2012 trend of the Arctic sea ice extent, a nearly ice-free
Arctic Ocean in September before mid-century is likely for RCP8.5

and

For completeness, the CMIP5 multi-model mean is also indicated with dotted lines. The dashed line represents nearly ice-free conditions (i.e., when sea ice extent is less than 10^6 km2 for at least five consecutive years).

But that is NOT what the simulations show. The simulations show the "5 year running mean" will dip below 1 M km^2 before mid-century. The simulations do NOT show anything about "5 consecutive years". There is a clear difference between these two metrics, as any editor with a scientific background should have noticed.

So the addition that made it into the Scientific Basis for Policy Makers is NOT sustained by scientific evidence, and appears to have made it into the final report without scientific reason, nor any indication who and why and exactly when that addition was made.

It's fishy. That's all I will say about it at this point.

[oren]

So the addition that made it into the Scientific Basis for Policy Makers is NOT sustained by scientific evidence, and appears to have made it into the final report without scientific reason, nor any indication who and why and exactly when that addition was made.

It's fishy. That's all I will say about it at this point.

Rob, I return to my comment from up-thread:

At least the why is easy, to downplay a visible and quick consequence of AGW.

I salute the research on the addition's history. But sometimes just the end result shows you the evil intention. Requiring 5 consecutive years means that even one "reverse outlier" voids the criterion, and buys a delay of 10 years or maybe more for the politico-deniers.

[Pmt111500]

So the addition that made it into the Scientific Basis for Policy Makers is NOT sustained by scientific evidence, and appears to have made it into the final report without scientific reason, nor any indication who and why and exactly when that addition was made.

It's fishy. That's all I will say about it at this point.

Rob, I return to my comment from up-thread:

At least the why is easy, to downplay a visible and quick consequence of AGW.

I salute the research on the addition's history. But sometimes just the end result shows you the evil intention. Requiring 5 consecutive years means that even one "reverse outlier" voids the criterion, and buys a delay of 10 years or maybe more for the politico-deniers.

Oh, they'll want the winters to be ice-free too? Thanks for digging this up, S.Pansa. The winters should go ice-free at some point too, no doubt, if there's no transition to solar and wind and other non-fossilic stuff, but the 10 year delay Oren estimates is way too short for this one. This should be in the news, but we do not live in a perfect world.

[binntho]

It's fishy. That's all I will say about it at this point.

Rob, I return to my comment from up-thread:

At least the why is easy, to downplay a visible and quick consequence of AGW.

I salute the research on the addition's history. But sometimes just the end result shows you the evil intention. Requiring 5 consecutive years means that even one "reverse outlier" voids the criterion, and buys a delay of 10 years or maybe more for the politico-deniers.

To me it seems to be two different questions: When will we see the Arctic without ice in summer (i.e. the first instance) and when will the Arctic be without ice in summer (a new state of the Arctic).

An outlier that dips below 1m Km2 one year is not a state-change, although it would be spectacular in its own right. What would follow is not obvious - perhaps the fact of an almost ice-free arctic causes a state-change in itself in the first year it happens, but on the other hand, perhaps we will see a growing number of such outliers over several decades until the "5 consecutive years" criteria is met.

However, does the criteria of 5 consecutive years constitute a state-change? Perhaps in a political sense, but I would think that a few decades would be needed to merit a scientific declaration of state-change if it happens slowly, with outliers dipping below the 1m Km2 mark a few times a decade.

However, the limit of 1m Km2 is in itself arbitrary - there is no reason to think that anything else changes suddenly (such as weather etc.) just because an arbitrary line on a graph is crossed.

[Rob Dekker]

So the addition that made it into the Scientific Basis for Policy Makers is NOT sustained by scientific evidence, and appears to have made it into the final report without scientific reason, nor any indication who and why and exactly when that addition was made.

It's fishy. That's all I will say about it at this point.

Rob, I return to my comment from up-thread:

At least the why is easy, to downplay a visible and quick consequence of AGW.

I salute the research on the addition's history. But sometimes just the end result shows you the evil intention. Requiring 5 consecutive years means that even one "reverse outlier" voids the criterion, and buys a delay of 10 years or maybe more for the politico-deniers.

Yes, oren. You have that right.
But it is still shocking to me to find such politically motivated statements in the main IPCC report for Policy Makers.

And I'm wondering about the IPCC integrity process now.

[P-maker]

Gents,

Allow me to remind you of a heated debate I had going last winter with Chris Reynolds in another thread, as well as my attempt at an early summary immediately after the release of the draft version of the AR5 Synthesis Report (SyR) of the Summaries for Policy-Makers (SPM) back in November 2014 in Copenhagen

(see brief description here: http://www.iiasa.ac.at/web/home/about/events/20140927-IPCC-SYR.html ).

On both these occasions, I put a big question mark on the attempted “change of definition” for a nearly ice-free Arctic Ocean.

Since I have also had the pleasure of attending a number of final IPCC plenaries (before AR5 that is), I may be able to offer some kind of explanation, as to what  happens between the final meetings and the release of the printed reports.

In the final plenary, all countries agree on the SyR/SPM text line by line. This does not necessarily include diagrams and figure captions, which may be changed by the secretariat in consultation with the scientists afterwards in order to update diagrams, correct errors, revise, filter time series, change colours and simplify diagrams.  The general rule however is that no new information must  enter the SPM unless there is a clear “line of sight” through the Technical Summary all the way to the Main Assessment Report and references to scientific papers or other evidence cited therein. Thus, when the decision was made to include the phrase “five consecutive years” in the SyR/SPM, changes would also automatically be inserted in the Technical Summary.

What I miss in all this, is the ”line of sight” all the way back to the scientific paper(s) suggesting this phrase or something similar. However, in order to trace this correctly, I assume it would require the assistance of someone - who was actually present back there in Copenhagen in October-November 2014 - to step forward and explain what happened.

[Peter Ellis]

In the final plenary, all countries agree on the SyR/SPM text line by line. This does not necessarily include diagrams and figure captions, which may be changed by the secretariat in consultation with the scientists afterwards  [...] Thus, when the decision was made to include the phrase “five consecutive years” in the SyR/SPM, changes would also automatically be inserted in the Technical Summary.

As I said above, this looks like a change to the figure caption that was intended to clarify the fact that the figure was showing five-year means (and which did so wrongly). The wrong clarification was then automatically propagated to all other mentions of "ice-free" in the document.  We can tell it's an error rather than a conspiracy because the caption is directly contradicted by the graph it refers to.

[S.Pansa]

P-maker, thank you very much for your insight! Very much appreciated.

In the final plenary, all countries agree on the SyR/SPM text line by line. This does not necessarily include diagrams and figure captions, which may be changed by the secretariat in consultation with the scientists afterwards  [...] Thus, when the decision was made to include the phrase “five consecutive years” in the SyR/SPM, changes would also automatically be inserted in the Technical Summary.

As I said above, this looks like a change to the figure caption that was intended to clarify the fact that the figure was showing five-year means (and which did so wrongly). The wrong clarification was then automatically propagated to all other mentions of "ice-free" in the document.  We can tell it's an error rather than a conspiracy because the caption is directly contradicted by the graph it refers to.

Well maybe - but I am not convinced, even more so as you, for some odd reason, keep mentioning a conspiracy here. As  far as I can see, you are the only one who is talking about a conspiracy.
Most others merely try to get a better grasp on the motives behind this change: are they purely scientific in nature? or more political ? No conspiracy needed (but if you like them, go along ...)

At least that is what I am interested in. Because if the change was politically motivated, the authority of this definition is not very strong, to say the least. Imo, of course.

Of course, in the end the reasons behind this change might very well be as simple as you say. But as I said, I am not convinced - for two reasons.

1) The figure caption reads as follows:

Figure SPM.7: ... (b) Northern Hemisphere September sea ice extent (5 year running mean) ...   The dashed line represents nearly ice-free conditions (i.e., when
sea ice extent is less than 10 6  km 2  for at least five consecutive years).  ... 

So first they say "5 year running mean" and 9 lines later (in the original caption) they all of a sudden change to "five consecutive years"? They could have simple written: "when the 5 year running man of sea ice extent is less ...". Because a "5 year running mean" & "5 consecutive years" are not really the same thing, aren't they. 

2) Nevertheless, that might be a slip. But in your quote of P-makers comment above there is another important phrase you didn't highlight.

... This does not necessarily include diagrams and figure captions, which may be changed by the secretariat in consultation with the scientists afterwards ...

Wouldn't a scientist immediately recognize that "5 year running mean" & "5 consecutive years"  are not the same thing?

Again, this might be just another slip, but then again: What is missing is

the "line of sight" all the way back to the scientific paper(s)

, as P-maker notes.

It would be really nice to hear from someone who was present back then.

But that all goes well above poor Pansas' head now. Time for a siesta!

[Peter Ellis]

Well maybe - but I am not convinced, even more so as you, for some odd reason, keep mentioning a conspiracy here.

Alleging that changes are silently being made to IPCC reports for political reasons, coupled with comments like "I'm wondering about the IPCC integrity process" look, sound and smell like conspiracy theory to me. Call it what you will.

1) The figure caption reads as follows:

Figure SPM.7: ... (b) Northern Hemisphere September sea ice extent (5 year running mean) ...   The dashed line represents nearly ice-free conditions (i.e., when
sea ice extent is less than 10 6  km 2  for at least five consecutive years).  ... 

So first they say "5 year running mean" and 9 lines later (in the original caption) they all of a sudden change to "five consecutive years"?

Exactly my point.  The first draft said  "5 year running mean", and that's what the graph shows.  In the final draft, the bracketed part "(i.e. when sea ice extent is.... etc)" was added, without changing the graph or any of the other associated text.  It's bracketed, and starts with 'i.e.' - both signs that it is simply an attempt to clarify the foregoing text, not to alter its meaning. The graph and original text were left unchanged.  There is thus very clearly no intent to change the meaning of the original text, and the fact that the two phrases mean different things is a mistake.

It looks like some copy editor has asked one of the scientists "Can you clarify what you mean by a '5 year running mean' in this caption", and been told "It means we average the values across a window of five consecutive years".  It would be quite easy for a miscommunication to lead to the bracketed phrase being wrongly inserted.

[BornFromTheVoid]

Single day NISDC extent has seen a sharp drop, down 120k, and now 64k below the 2007 minimum. That guarantees at least the 2nd lowest extent minimum on record.

The 5 day average still has a little way to go, now just 47k off 2007.

[Tigertown]

That puts NSIDC at 4.083 M for SIE for 9-07-2016. I don't know if I remember their number and  that of  JAXA (IJIS) being as close  together at any point all year as they are now.

[Lord M Vader]

Have there been any century break per NSIDC for the month of September?

Where at NSIDC did you find the number 4,083 Mn km² BFTV and Tigertown?

//LMV

[Tigertown]

Here.

ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/north/daily/data/NH_seaice_extent_nrt_v2.csv

[BornFromTheVoid]

Have there been any century break per NSIDC for the month of September?

Where at NSIDC did you find the number 4,083 Mn km² BFTV and Tigertown?

//LMV

There have been over a dozen 100k+ drops in September previously. Noise is probably a large contributor though

[Lord M Vader]

Thank you both for the quick replies!

Noise yes, and the coarse resolution NSIDC is using to have homogenity should contribute too.

[RoxTheGeologist]

So the addition that made it into the Scientific Basis for Policy Makers is NOT sustained by scientific evidence, and appears to have made it into the final report without scientific reason, nor any indication who and why and exactly when that addition was made.

Rule making is a fast and furious process in the redlines that are handed around in the last throes before a vote takes place and it becomes set. The person who can afford the best lobby will be the one most on-top of those changes. It's a great example of how money buys law. I would bet the API or someone similar got that change in. Don't underestimate how well funded, well informed and insightful the petroleum lobby is.

[S.Pansa]

Well maybe - but I am not convinced, even more so as you, for some odd reason, keep mentioning a conspiracy here.

Alleging that changes are silently being made to IPCC reports for political reasons, coupled with comments like "I'm wondering about the IPCC integrity process" look, sound and smell like conspiracy theory to me. Call it what you will.

1) The figure caption reads as follows:

Figure SPM.7: ... (b) Northern Hemisphere September sea ice extent (5 year running mean) ...   The dashed line represents nearly ice-free conditions (i.e., when
sea ice extent is less than 10 6  km 2  for at least five consecutive years).  ... 

So first they say "5 year running mean" and 9 lines later (in the original caption) they all of a sudden change to "five consecutive years"?

Exactly my point.  The first draft said  "5 year running mean", and that's what the graph shows.  In the final draft, the bracketed part "(i.e. when sea ice extent is.... etc)" was added, without changing the graph or any of the other associated text.  It's bracketed, and starts with 'i.e.' - both signs that it is simply an attempt to clarify the foregoing text, not to alter its meaning. The graph and original text were left unchanged.  There is thus very clearly no intent to change the meaning of the original text, and the fact that the two phrases mean different things is a mistake.

It looks like some copy editor has asked one of the scientists "Can you clarify what you mean by a '5 year running mean' in this caption", and been told "It means we average the values across a window of five consecutive years".  It would be quite easy for a miscommunication to lead to the bracketed phrase being wrongly inserted.

Hi Peter, I have answered your post in another thread (Ice free predictions and their uncertainty), were I tought it is more fitting. Hope nobody minds.

[Neven]

Thanks, S.Pansa. I wanted to propose the same, but couldn't find a similar thread that Juan Garcia had opened (with a poll), where we also discussed the silly 5-year ice free stuff.

Everyone, please follow S.Pansa's link. Wipneus is about to return, so let's keep his thread tidy from now on. 

[Neven]

Hold on, I found it: IPCC AR5 Definition of "Nearly ice-free conditions"

Please, continue there. Sorry for not finding it earlier.

[Niall Dollard]

Single day NISDC extent has seen a sharp drop, down 120k, and now 64k below the 2007 minimum. That guarantees at least the 2nd lowest extent minimum on record.

The 5 day average still has a little way to go, now just 47k off 2007.

The 2007 min listed on NSIDC, is 4.154 million km². Is this the 5 day trailing average min for the 5 days Sep14-Sep18?

Does anyone know the lowest single day SIE for 2007 ?

[BornFromTheVoid]

The 2007 min listed on NSIDC, is 4.154 million km². Is this the 5 day trailing average min for the 5 days Sep14-Sep18?

Does anyone know the lowest single day SIE for 2007 ?

You have the dates correct. The lowest single day value is 4.147 from the 14th.
The 5 days from the 14th to the 18th are (in millions km2):
14th: 4.147
15th: 4.167
16th: 4.153
17th: 4.149
18th: 4.156

[Bill Fothergill]

The 2007 min listed on NSIDC, is 4.154 million km². Is this the 5 day trailing average min for the 5 days Sep14-Sep18?

Does anyone know the lowest single day SIE for 2007 ?

Question 1: Yes. Please see http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
Charctic gives a trailing 5-day average, and if you click on Sep 18 2007, you will see that 4.154 value.

Question 2: The lowest single day SIE for 2007 in the NSIDC database was 4.147 million sq kms on the 14th September. If that seems too close to the 5-day value, it's because there was only a 20k spread across those 5 days.
You can find this data if you follow the Arctic Sea Ice Graphs link from the Arctic Sea Ice Blog.

[Bill Fothergill]

Ha! I see that BFTV replied whilst I was still typing.

[Niall Dollard]

Thanks for quick replies !

Interesting also to see only a 20k spread over those 5 days in 2007, unlike at present when it's still making big jumps (downwards).

Historically I wonder do the daily values tend to flatten out as we near the actual min or perhaps the greater day-to-day variability is related to different sensor being used now or perhaps the nature of the ice this year (more rubble?).

[Bill Fothergill]

... I wonder do the daily values tend to flatten out as we near the actual min  ...

Niall,
In any system that exhibits quasi-sinusoidal behaviour (or anything even approximating thereto) one would expect to see flattening of the response curve near both the maximum and the minimum.

This is clearly displayed on the Charctic site for the 1981-2010 average and the +/- 2 Stnd Dev plots. The ADS/IJIS plots for the 1980s, 1990s and 2000s exhibit exactly the same behaviour, as will any of the SIE or SIA databases.

(NB Non-sinusoidal responses - such as saw-tooth waveforms - do not demonstrate this flattening at the turning points.)

[BornFromTheVoid]

Slight increase in the single day NSIDC extent values (+21k) but the 5 day average is still dropping, now just 15.4k off the 2007 minimum. Barring a big increase in the single day values tomorrow, the 5 day average should drop below the 2007 minimum on tomorrows update.

[Lord M Vader]

In order to superseed the 2007 minimum per NSIDC 5 day average, we need a value lower than 4,179 Mn km² tomorrow. Shouldn't be an impossible task given todays value at 4,104...

[BornFromTheVoid]

It's done, the 5 day NSIDC extent average is now below the 2007 minimum, securing the title of 2nd lowest minimum on record

[Pmt111500]

It's done, the 5 day NSIDC extent average is now below the 2007 minimum, securing the title of 2nd lowest minimum on record

This could be in the news! Thanks for the info.