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"Only in April, Arctic sea ice had staged an impressive recovery and was close to the 1979-2012 average"

That was purely sea ice extent. Volumes have been steadily going down to the point that some researches refer to much of the 'recovered' ice as rotten or a slushie. That accounts somewhat for the steep decline from near average extent to record low.

Yes, and crucially very different from the Little Ice Age (which certain groups seem convinced will re occur today) when arctic ice extent increased substantially - according to past research.

We are currently in an inter-glacial period between ice ages.
During such periods, the Earth is ice-free, even at the poles.
About 12500 years ago, Britain was covered in an ice sheet, since when
the extent of the ice has been declining.
Is it surprising that the ice is still declining?
Would it be a good thing if the ice was extending?

The LIA is interesting. Some say we are still exiting from the LIA so the warming and ice loss are due to that. Others are saying we are entering a LIA and cooling has started. Both can't be right (though both could have wrong conclusions!).

A quick word on the satellite record

According to the final report of working group 1 of the intergovernment panel on climate change sea-ice extent has been measured by satellits since the early 1970s



"Especialy importantly, satellite observations have been used to map sea-ice extent routinley since the early 1970s. The American Navy Joint Ice Centre has produced weekly charts which have been digitised by NOAA"

Page 224

My 1950's encyclopedia tells me that the Russian ports along the coast of Siberia were building a roaring trade in the early part of the 20th century transporting mainly flax along the northern sea board. Arctic ice extent was lower than today and the ships sailed for many months during the year. As I personally recall, during the 1950's the ice returned with vengeance and all the ports closed and trade ceased completely by the end of the 50's.

It's only in the past few years that this sea route has become navigable again. There's also piles of other historical evidence that ice was low then than today.

So no problem just cyclic and boy I鈥檇 not like to see it going in the other direction!!

The NSIDC have good shipping/photos/naval records back to the 1950's and satellite data from the late 1970's.

Come on, you'll be mentioning submarines next...

john_cogger @7 you say:

"The NSIDC have good shipping/photos/naval records back to the 1950's"

Agreed. The 50's was when I remember the ice returned with vengence and the shipping trade decreased and the ports shut down. I was talking the previous 50 years when it was in its heyday. Check it out for yourself.

Your chart starts at the high point of last century. Makes sense.

Thanks John for the NSIDC sea ice data back to the 1950's
Ofcourse temperature data up in the Arctic has been available for much longer.
Climate4you show this graph based on hadcrut3 data



The temperatures back in 1935-45 were just as high as today
First commercial crossing of NW passage was 1942
Look at that temperature rise from 1915 to 1920's!
No rise in CO2 about then

How long has satellite information been available, more fear, false evidence appearing real. I would be more concerned about the next 30/40 years, when winters become much colder and food production slows. I wonder what caused the dip in world temperatures after the 2nd world war, when industrial production went through the roof.

Meanwhile, the HadCRUT3 anomaly figure for July has just been published at 0.446c, slightly down on last month's 0.477c, while the N.H. figure was up from 0.661c to 0.687c and the S.H. was down from 0.293c to 0.205c.
All of the major global & S.H. anomaly figures showed slight falls, while only HadCRUT3 showed an increase in the N.H.
In reality, global temperatures have been fairly stable since April and based on the latest AQUA CH5 temperature figures, should remain so in August, possibly showing slight increases over the July figures, i.e. returning to approximately the same levels as in June.

Graph here suggests sea ice extent in August 1938 was substantially greater than in August 2012

@9 Neilhamp

Not sure if the St Roch in 1942 was a commercial vessel but it took 28 months to make the journey. Many times the vessel was frozen in ice.

The ice extent was also probably much greater in 10000 b.c.

This report, from NSIDC satellites, is not unexpected given the fact that the NSIDC reported the data from their old satellites which use microwave measurements. These old satellites have a problem with detector degradation that is well documented. There was also a severe storm in early August which broke the ice into pieces and the microwave detectors on these old satellites cannot detect broken ice accurately. The data from these satellites is not reliable. The latest satellites, used by NSIDC and NASA, which do not have the same problems, show ice coverage some 30% above the 2007 ''lowest ever'' figure. But this data was not released to the media presumably to continue the alarmism of AGW.
Arctic climate cycles are approximately 80 years in length. Satellite observation has been in situ for 33 years, not even half the normal cycle, so why do we attach such importance to this iffy data set from degraded satelites?

I am wondering why, given that Antarctic ice is still expanding, that this information has not been reported? Recently reports that 25 states of the USA had record(?) temperatures again failed to note that the other 25 states experienced ''lower than average'' temperatures. I might add that the highest ever temperatures in the US were during the 1930's.

John Marshall wrote:
"I am wondering why, given that Antarctic ice is still expanding, that this information has not been reported?"

Probably because the increase in Antarctic ice is what many climate models predicted as an initial sign of global warming. Hansen mentions increased snowfall and net net ice sheet growth in a paper over 30 years ago;

John Marshall it is nice to see somebody on here with common sense. Too many have watched the day after tomorrow and believed it was true, I am sure that is where the climate modellers get their data from. The met office can't even get a daily forecast correct, they put that many different outcomes out, they have to be eventually right.

@18 Tim

The info on the arctic isn't a model. Its now, it's data, it's whats happening right now.

With cold winters being linked to the drop in ice in the arctic, I'd of thought you'd be happy. You might get the foot deep snow you so often predict.

#17. - Lazarus wrote:
Probably because the increase in Antarctic ice is what many climate models predicted as an initial sign of global warming. Hansen mentions increased snowfall and net net ice sheet growth in a paper over 30 years ago;"

He may mention it, but from this quote from the blog, he doesn't seem to be coming down one way or another.
鈥淢elting of the world鈥檚 ice sheets is another possible effect of CO2 warming.
If they melted entirely, sea level would rise ~ 70 m. However, their natural response time is thousands of years, and it is not certain whether CO2 warming will cause the ice sheets to shrink or grow.
For example, if the ocean warms but the air above the ice sheets remains below freezing, the effect could be increased snowfall, net ice sheet growth, and thus lowering of sea level.鈥�
I am not sure that this is predicting an increase in Antarctic ice at all, more outlining the possibility that global ice "could" be net (global) ice sheet growth.
Also, it associates such growth in ice sheets with lowering sea levels, which afaik isn't happening.
What we seem to be getting is a decline in sea ice in the Arctic and an incease in the Antarctic.
Is it snowing less in the Arctic and more in the Antarctic?

Antarctic is generally a much colder place. also from what the scientists are saying the decline is largely attributable to the lack of thicker multiyear ice. Conditions over the Arctic apparently have not been that different from normal but as a substantial proportion is now single year ice it is prone to break up. Associated with the Greenland melt that occurred in July there is certainly reason for concern and if this pattern is maintained will represent a very serious development.

John Marshall: "This report, from NSIDC satellites, is not unexpected given the fact that the NSIDC reported the data from their old satellites which use microwave measurements. These old satellites have a problem with detector degradation that is well documented. There was also a severe storm in early August which broke the ice into pieces and the microwave detectors on these old satellites cannot detect broken ice accurately. The data from these satellites is not reliable."

It's consistent. The satellites had the same set of problems back in 2007 yet 2007 wasn't as low. It's a record which ever way you look at it. 2007 was blamed on wind and now you want to blame 2012 on a storm. You are running out of excuses. What will you say in 2013 or 2014 if a record is broken again? Why not just accept the fact that the sea ice is depleting?


"The latest satellites, used by NSIDC and NASA, which do not have the same problems, show ice coverage some 30% above the 2007 ''lowest ever'' figure. But this data was not released to the media presumably to continue the alarmism of AGW."

That data is actually less reliable for comparing different years. It also now only shows ice about 17% above the 2007 figure, so I think it'll probably go below 2007 too within a week.

"Arctic climate cycles are approximately 80 years in length. Satellite observation has been in situ for 33 years, not even half the normal cycle, so why do we attach such importance to this iffy data set from degraded satelites?"

Because there is no such 80 year cycle and the satellites are not degraded.

Along time ago 1950/1960 I read an article in a magazine. It was about Russia building huge dams across some major rivers that flowed into the artic ocean. It went to say that this would reduce the amount of fresh water flowing into the Artic Ocean. There will be less ice formed, intime affecting the ice sheet. Is this prediction coming true?

#22 quake needs to read information about climate cycles. the Arctic cycle is approximately 80 years long. It is also true that when the Arctic sea ice area reduces there is an increase in Antarctic sea ice. This is happening-so real data from observations. The satellites do certainly degrade, a well reported problem, so that is why the new satellites were put in place. The data from NASA satellites show ice at a 28% larger area than 2007.
Arctic sea ice predictions certainly come from models not observations since a prediction is for the future. (John_Cogger please note).
But if you wish to believe old poor data sets it is up to you.

11. QuaesoVeritas:

Thanks for the HadCRUT3 updates. Can you possibly post a link to these? I did have one, but I've lost it.

I make HadCRUT3 now +0.371C for 2012 to date. If you're right about August being up slightly, then it should push 2012 inside the top ten warmest in HadCRUT3. I note that April, May, June and July were all inside the top ten warmest in their respective months. Anything above +0.42 would do the same for August.

A more comprehensive analysis of the August 2012 Arctic ice situation, and a comparison with NSIDC's own MASIE data which does not directly concur, is available here:

16. John Marshall wrote:

"Recently reports that 25 states of the USA had record(?) temperatures again failed to note that the other 25 states experienced ''lower than average'' temperatures."

That's odd. NOAA publishes a monthly map of states based on temperature averages (or 'normals'). Here's July 2012, from which you can easily navigate right back through the year. I make recent 2012 monthly temperatures state by state as follows:

July: No states below normal temp. Four states 'normal', the rest either 'above' or 'much above' normal and one one 'all-time' record high.

June: Five states 'below normal', one 'much below' normal. 13 states 'above normal', seven 'much above' normal, and one 'all-time' record high.

May: Two states 'below normal'. Three 'normal'; the rest either 'above normal' or 'much above' normal.

You can go right back to January. There are very few occasions where a US state suffered below average monthly temperatures in 2012.

So I'd be interested to know where you obtained the information that "25 states experienced ''lower than average'' temperatures"?

26.dispozest wrote:

"A more comprehensive analysis of the August 2012 Arctic ice situation, and a comparison with NSIDC's own MASIE data which does not directly concur, is available here:..."

I take it you followed the comments in that link, in which the scientist quoted by Watts, Dr. Walt Meier, makes an appearance and explains that the IMS data used by NSIDC and the MASIE data are in fact one and the same?

As Dr. Meier states: "MASIE is simply a repackaging of the IMS data in easier to use formats." He goes on to explain that the MASIE data uses higher resolution in order to identify minute details in the ocean, such as ice bergs, or narrow channels, etc.

NSIDC extent values are based on gridded areas of the Arctic in which more than 15% of the surface area is covered in sea ice. The MASIE product, having a much higher resolution, includes areas with less than 15% sea ice, hence the greater apparent surface area.

Obviously, areas with less than 15% sea ice can not reasonably be considered to be 'ice covered', and never have been historically.

Re 27.

John Marshall. Sorry, I forgot to post the link to NOAA monthly 'normals'.

]=Statewidetrank&submitted=true#maps

Use the blue

I tend to agree with newdwr54. The WUWT discussions included postings by Meier and Stroeve which were not well received by other regular posters including Watts. This was disappointing, since the sceptics seemed to be arguing over the minutiae, whereas Meier and Stroeve seemed reluctant to acknowledge the obvious effects of the recent arctic storm. I assume that they were being cautious - so as not to allow anything they said to be mis-reported in the future - I don't blame them.
The storm clearly mushed up the thin ice in rapid time and helped to set the new record low. That said, sea ice had been tracking very low anyway and could easily have set a new record without the help of the storm.
It will be interesting to see if there is another short melt season this year. A little simplistic perhaps, but it strikes me that the more arctic sea melts, the quicker it can reform as the sun approaches the horizon.

newdwr54,

Here is a link to all of the UKMO Hadley Centre datasets:



It is hard to find on the MO website.

Also loading pages and downloading can be a bit slow.

Nic Lewis has a letter in the Guardian, interesting.

#30 lateintheday

I think the most revealing quote from the WUWT Arctic sea ice thread came from Walt Meier:

"The folks at NIC do a great job at what they鈥檙e focused 鈥� navigational support. MASIE is an excellent data set and we at NSIDC find it very useful looking at specific details about the ice (e.g., is the Northwest Passage open or not), but the NIC products are not applicable to studying climate-scale changes."

You could argue the same for the whole satellite record.

Wow. I can't believe that there are actually people here who think that the ongoing loss of arctic sea ice is not happening or is just due to variations in weather. Today, it was announced that a new record was set for low Arctic sea ice volume. This means that all three major measures of Arctic sea ice have set new low records this year - area, extent (area with at least 15% sea ice coverage), and volume. Of these, volume is the most important because it is the only one that takes ice thickness into account, so it is the measurement that most accurately reflects the amount of ice present in the Arctic.

It is important to note that by volume, 9 of the past 11 years have shown record lows. That is not a temporary change due to fluctuations in the weather - that is a long term, ongoing changes - changes in climate. Also, some people want to claim that the record low sea ice extent in 2007 was due to weather, but they never mention that the sea ice extent for every year since 2007 woul be a new record low for the years prior to 2007. Once again, that is climate change, not weather.

Here is a good post showing the difference between weather and climate in terms ofArctic sea ice extent:

I forgot to include a link to the graph showing hust how rapidly the Arctic sea ice is melting:

Note that unlike the maximum area and extent ( both of which recover to typical levels each year) the maximum volume has been sharply declining over the last several years. This means that maximum area and extendt are being formed with thinner ice over time. Thinner ice requires less heat to melt, which is why we continue see record low area even though the maximum area is closer to the typical value for most years.



Taken from:

I was looking at the daily changes in ice extent, based on IARC-JAXA figures this year, compared to other years and I noticed that there have been several unusually large falls in extend, some at times of the year when they wouldn't be expected.
However, usually these have been followed fairly quickly with unusual rises in extent within a few days, and I wondered if these changes are "real" or simply "noise".
The most extreme of these are as follows (figures in km^2):
Feb. 1st -145,000
Feb. 2nd +63,438
Feb. 3rd +155,312

Feb. 14th -68,906
Feb. 15th +146,250

Feb. 21st -101406
Feb. 23rd +127,500

Feb. 29th -135,156
Mar. 1st +197,031
Mar. 2nd +231,156
Mar. 3rd +93,907

Mar. 24th -204,687
Mar. 26th +148,750

Apr. 18th -183,907
Apr. 19th +65,000
Apr. 20th +46,719

Jun. 19th -167,656
Jun. 21st +64,375

This year does seem to have seen an unusual number of large swings in extent based on these figures and I wonder if such large swings, within the space of a few days, are even possible, especially in winter. At the very least, these seem to suggest something unusual is going on this year. For example, this year has seen both the largest recorded daily fall in extent, on March 24th, and the largest increase, on March 2nd, since 2003.
Of course it is possible that the areas involved are the same "marginal" regions, which oscillate between ice and no ice.

Snowman - If I understand you correctly, then I agree - the satellite record is much too short to account for climate cycles, useful though it is. I strongly suspect that there is a natural cycle associated with arctic sea ice. This may be as simple as a lagged response to PDO or AMO alongside solar variation.
However, I'm also quite willing to accept that the long term trend in summer sea ice would be downwards. To my mind, this is what you might expect as a consequence of emerging from the LIA.
One of the comments that caught my eye was the assertion that lower summer sea ice was a net negative feedback. Again, intuitively this makes sense. As direct solar forcing at these latitudes has been on the decline since the peak in June, the additional energy reaching the ocean (due to lower extent) is marginal and decreasing during the weeks of lowest extent. However, this now open water with its increasing surface area is able to radiate freely until the ice re-forms.

#27 I was quoting the data from Joe Bastardi whose data sets do not always agree with NASA etc. but then not many in America do agree with NASA on global temperatures since it has turned out, in the past few weeks, have been correcting (inflating) their recent temperature records probably to get in agreement with their models.

31. QuaesoVeritas:

thanks for the links QV.

39. John Marshall wrote:

"I was quoting the data from Joe Bastardi whose data sets do not always agree with NASA etc."

The data I referenced are from NOAA, not NASA. I don't know where does Joe Bastardi get his data from? Let's hope it's not the same place he got the data that he based this 2010 prediction of future Arctic sea ice minimum extent from:

His "studies" showed him that it would recover to 2005 levels in 2011 and then continue to expand for 20-30 years. "I think you'll see that I'm going to be right about this."

Commiserations, Joe.

lateintheday - agreed, it seems to me that what we have with the satellite record (thus far) is a snapshot in climate terms of where we are in a cycle. It seems obvious to me that we are currently seeing some pretty dramatic changes in the Arctic, but why the changes are taking place seems less clear given that this process seems to have happened (many times) before.
I find it refreshing that there is still so much that we just don't fully understand.

42. thesnowman wrote:

"I find it refreshing that there is still so much that we just don't fully understand."

It would be really refreshing and far more productive if the heads of our scientific and political organisations admitted that "we just don't fully understand".

Closing down scientific debate is not going to improve the wellbeing of mankind or the planet. A planet which they have now asssumed they can control?

Interestingly the 2007 melt was 10 years after the powerful 1997/8 El Nino and the present melt is ten years after the 2002/3 El Ninos.

2015 would be ten years after the next sizeable El Nino around 2005 so we'll probably get another large melt then.

However the power of El Ninos relative to La Ninas has been declining of late so from now to 2015 the ice should recover a bit before the next large melt then from 2015 to 2020 it should recover quite a bit before the 2010 El Nino reaches the Arctic Ocean around 2020.

It looks like El Nino strength will now decline for a few decades due to the quiet sun, negative PDO and soon a negative AMO so I doubt we will beat the 2012 for many a year to come unless 2015 beats it by a slight margin.

Unless the sun picks up soon then cooling and ice recovery should be well under way by 2020.

44. Stephen Wilde wrote:

"Interestingly the 2007 melt was 10 years after the powerful 1997/8 El Nino and the present melt is ten years after the 2002/3 El Ninos."

I have been watching SSTs for many years and the present question is where did all the "warm" water in the NH come from and why only in the NH?



Some say changes in PDO/AMO, some say solar, some say CO2, I say I don't know other than the CO2 global predictions have not yet come to pass.

I am beginning to think that we have no concept of just how large a flywheel we are trying to observe the effects of

#41
And where does NOAA get its data? NASA since they are part of the same empire. Bastardi is correct if the data from newer satellites is used rather that from degraded older ones.
So your data comes from NASA old satellite data the same as that reported by NSIDC.
NOAA,NASA,NSIDC,NCDC, all hands in the same glove so I would expect broad agreement on a report such as spawned all this blogging.

46. 1st Sep 2012, John Marshall wrote:

"So your data comes from NASA old satellite data the same as that reported by NSIDC."

NOAA uses its own satellites, not those of NASA. In addition there are satellites used by the Japanese and Danish Met offices, and others, to track Arctic sea ice.

Every single one of them is currently showing record minimum extent and area. They must all be wrong?

Does anyone here routinely check the HadCRUT3 data files on the UEA/CRU website?
A few days ago they only went to March 2012 but after I queried this with them, they now go to June 2012, but they have implied that they haven't changed them as a result of me asking the question.

@48. QV

"Does anyone here routinely check the HadCRUT3 data files on the UEA/CRU website?"

No I used to but gave up when you explained about the difference in "averages" calculated by UKMO and CRU.

However I think your prompting may well have triggered the update. I have been wondering why Wood for Trees HadCRUT data had not been updated since March, I actually checked yesterday. Just had a look now and WfT is now up to date?

Coincidence?

Yes I noticed that too.
I don't think it's coincidence, but getting the CRU to admit it might be difficult.
Either they are deliberately trying to pretend they had already updated the figures, or they don't know what they are doing. I suspect the latter.
Note WfT figures go to June 2012, the same as CRU, but the MO have updated to July.

Yup, looks like WfT uses CRU. as for "getting CRU to admit it". Doubt I would try, not sure what could be gained in chasing them?

It's a matter of principle.
I find it annoying when such people try to pretend there wasn't a problem,
when there was, and implying that I was wrong to boot!

52. QV

"It's a matter of principle."

Point taken QV, I did not pick up that they were implying you were wrong. Maybe an official letter of complaint to the head of department?

'Unprecedented!' 'Lowest on record!' On records that don't go back very far. Wow. How about 1817 and 1922?

Dr. Tim Ball, a Canadian climatologist who has worked for years in the Arctic, has written a critique of the data on his web site. He has little confidence in satellite data of the ice due to several limitations of the detectors on the satellites.
http//:www.drtimball.com will get you there.

NOAA/NASA operate satellites under their own names but share the data. NASA launches NOAA satellites and does the management so basically they are NASA satellites.

#53. - greensand wrote:
"Point taken QV, I did not pick up that they were implying you were wrong. Maybe an official letter of complaint to the head of department?"
The exact words were:
"I just looked, and the HadCRUT3 data runs to June 2012:

I know there were delays in getting it updated, as it's now all done jointly with the Met Office."
Given that I had said the figures were not updated, I think the above implies that I was mistaken, although what he said could have been literally correct, if he had just updated the figures himself. I have had some personal experience of "covering up" errors and omissions, so I know how these things work!
The second bit, which implies that the delays were due to the figures being done jointly with the MO is a bit rich, since the MO have been updating the figures more regularly than CRU.
I would have expected something like "I have checked the files and you were correct about the missing figures, which have now been updated, thank you for letting us know."
I don't think I would go as far as making a formal complaint, I don't have the time to waste on that, apart from the fact that I can't really prove anything. Who would the head of department be, Phil Jones? I don't want to be accused of wasting his time either!

@56 QV

"I just looked, and the HadCRUT3 data runs to June 2012:

I know there were delays in getting it updated, as it's now all done jointly with the Met Office."

If I recall correctly (not always the case) CRU always reported HadCRUT data before the UKMO? That was the reason for my preference to CRU as the source of data.

I wonder if the above statement is inferring that CRU had been awaiting UKMO or if the posting at CRU is now carried out by the MO? Why would he need to check if his own web site had been updated? But hey, ho..

I agree don't think there is much to gain in complaining but it maybe interesting to watch the timing of future MO and CRU data releases.

55. John Marshall wrote:

"Dr. Tim Ball, a Canadian climatologist who has worked for years in the Arctic, has written a critique of the data on his web site."

All well and good apart from one thing; Dr Tim Ball is a retired geography professor at the University of Winnipeg. He is not now and never was a "climatologist", despite his previous claims to the contrary.

Also, I can find no reference anywhere, including his many own personal profiles, that support your claim that he "worked for years in the Arctic". He wrote or co-wrote a couple of papers about past climates in N. Canada.

That doesn't alter the value or otherwise of the opinions he expresses in the article you link to, it just places them in context.

QV & GS,

As far as I know the reason HadCRUT3 has not been updated regularly is because it is no longer considered by CRU to be a 'valid' data set. Its method for extrapolating temperatures in regions not covered by temperature stations has been acknowledged as invalid.

HadCRUT4 improves on this, and brings the CRU data into line with the other surface station providers and satellite data. CRU is engaged in updating their data to HadCRUT4, which I presume will be the standard used by IPCC AR5. HadCRUT3 will probably be maintained in conjunction for a while for historical reasons (so we can still settle our 2012 predictions competition!).

newdwr54,
Have you any hard evidence for that?
I know that HadCRUT3 is going to be replaced by HadCRUT4 *eventually* but at the moment the latter only goes to December 2010.
In all of my enquiries with the MO and CRU regarding the late update of HadCRUT3 figures, they have never stated they are not updating the figures because they consider HadCRUT3 to be invalid.

54. buythermals wrote:

"'Unprecedented!' 'Lowest on record!' On records that don't go back very far. Wow. How about 1817 and 1922?"
________________________________________

Yes, what about 1817 and 1922? What evidence is there that these years surpassed or even came anywhere close to this year's Arctic sea ice extent minimum? We have several peer reviewed reconstructions of Arctic sea ice extent going back hundreds of years based on proxy data, observations or both.

This graph shows observational summer Arctic sea ice extent data (ships' logs; regional data sets; aerial reconnaissance) between 1870-2008 [Walsh and Chapman, 2001] combined with satellite observations from 2009-2011 [NSIDC]:

You can see that 1922 was unexceptional, even for the period. So "What about 1922" indeed?

This graph shows reconstructed average annual Arctic sea ice extent (from ice cores; tree rings; lake sediments) over the past 1,450 years [Kinnard et al. 2011]:

You can see these indicate that Arctic sea ice average annual extent was probably ~ 1.5m km2 greater in 1817 than it is today. So yes, "What about" 1817?

60. QuaesoVeritas wrote:

"In all of my enquiries with the MO and CRU regarding the late update of HadCRUT3 figures, they have never stated they are not updating the figures because they consider HadCRUT3 to be invalid."

Yes, 'invalid' was a bad choice of word. HadCRUT3 is obviously valid as it stands, i.e. it does what it says on the tin.

However, as Jones et al. (2012) state in their abstract, the new CRUTEM4 database reflects updated and re-analysed data and includes new additional data (particularly from the Russian Arctic). This causes it to differ substantially from CRUTEM3, which contributes the land portion of HadCRUT3 temperatures.

As such, HadCRUT4 is clearly seen as an 'update' on HadCRUT3 (as HadCRUT3 was an update on HadCRUT2, etc). Therefore HadCRUT3 is no longer 'valid' in the sense that it is not considered to be the latest or best CRU representation of changes in the global surface temperature; not in the sense that it is 'wrong', as my terminology may have implied earlier.

Since the HadCRUT4 data were released in March, CRU has not updated its HadCRUT3 data on the official site on a regular basis. Hopefully HadCRUT4 updates will commence shortly and both will run in conjunction for a time.

@59. newdwr54 wrote:

"As far as I know the reason HadCRUT3 has not been updated regularly is because it is no longer considered by CRU to be a 'valid' data set."

Nah DW there is no evidence of that. The UKMO is still updating HadCRUT3, as confirmed by the correspondence posted by QV, and now after prompting so is CRU. Also the MO is still making and reporting their Decadal Forecasts against HadCRUT3.

Eventually HadCRUT4 will appear until then the only metric being updated by the MO is HadCRUT3.

The lack of updating of HadCRUT3 since March until now is nothing to do with HadCRUT3 as you probably correctly posit - "Hopefully HadCRUT4 updates will commence shortly and both will run in conjunction for a time."

Correction to last para in 63 above:-

should reda ..."nothing to do with HadCRUT4"...

#62. - newdwr54 wrote:
"Since the HadCRUT4 data were released in March, CRU has not updated its HadCRUT3 data on the official site on a regular basis. Hopefully HadCRUT4 updates will commence shortly and both will run in conjunction for a time."

But is there any evidence to suggest this is anything other than coincidence?
I will ask the person who replied directly to my recent e-mail directly.

GS,

I know the MO is updating HadCRUT3 since, as you point out, it is the only metric currently available. However, referring to my comments to QV above, CRU has been very lax in updating its official HadCRUT3 website since March, when the latest HadCRUT4 was issued.

In the Jones et al. paper published by CRU in March it is made clear that HadCRUT4 is effectively the CRU's latest and best attempt at a global dataset. It effectively replaces HadCRUT3; as HadCRUT3 replaced HadCRUT2.

Therefore I can understand why CRU is not rushing to update its HadCRUT3 database every month (the MO do this anyway). In this sense, HadCRUT3 is no longer the current, or 'valid' (though that's probably a poor word choice on my part) CRU 'gold standard'.

i don't see anything suspicious about this.

#66. - newdwr54 wrote:
"i don't see anything suspicious about this."
I wasn't suggesting anything suspicious, but I wouldn't be surprised if HadCRUT3 hadn't been *informally* been given a lower priority.
I think it is more likely to be lack of resources.

65. QuaesoVeritas wrote:

"But is there any evidence to suggest this is anything other than coincidence?"

I'd say it's probably *not* a coincidence.

Why would CRU urgently update their online HadCRUT3 dataset when they've already de facto admitted that it contains data that is 'wrong', i.e. that is not homogenized using the latest information and that has been independently re-analysed producing different results? It also contains less spatial coverage than CRU now currently has available to it.

It's not as if they've hidden the HadCRUT3 data. They still make it available, as you know, and it's still published (admittedly obscurely) on a monthly basis by the MO.

In short: why would CRU (or MO) make a fuss about updating and publicising a data set they've effectively already admitted they know is flawed? That's all it boils down to, as far as I can see.

#68. - newdwr54 wrote:
"In short: why would CRU (or MO) make a fuss about updating and publicising a data set they've effectively already admitted they know is flawed? That's all it boils down to, as far as I can see."
There is a difference between not "urgently" updating their dataset and not updating it for 4 months. It hasn't been replaced by HadCRUT4 yet and it remains the only official MO/CRU global temperature dataset.
In fact, by not updating it in a reasonably timely manner, they are drawing more attention to it's flaws than would otherwise be the case.
If HadCRUT4 is so "great", why hasn't it been updated beyond December 2010 yet?

What about 1922?


What about 1817?


It doesn't fit the 'unprecendented' meme so can safely be ignored. :)

@66. newdwr54 wrote:

"i don't see anything suspicious about this."

Neither do I! Never did, I actually accept what CRU said:-

"I know there were delays in getting it updated, as it's now all done jointly with the Met Office."

Nothing suspicious quite an acceptable statement.

The introduction of HadCRUT4 being the reason for the delays is purely supposition on your behalf, I happy to accept the CRU statement until they say differently