Excerpt from The Inconvenient Skeptic by John Kehr
The longer I am involved in the global warming debate the more frustrated I am getting with the CRU temperature data. This is the one of the most commonly cited sources of global temperature data, but the numbers just don’t stay put. Each and every month the past monthly temperatures are revised. Since I enter the data into a spreadsheet each month I am constantly seeing the shift in the data. If it was the third significant digit it wouldn’t bother me (very much), but it is much more than that.
For example, I have two very different values for January of 2010 since September 2010. Here are the values for January based on the date I gathered it.
Sep 10th, 2010: January 2010 anomaly was 0.707 °C
Jan 30th, 2011: January 2010 anomaly is now 0.675 °C
That is a 5% shift in the value for last January that has taken place in the past 4 months. All of the initial months of the year show a fairly significant shift in temperature.
Monthly Temperature values for global temperature change on a regular basis.
Read the entire post here
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Some of this may be related to late reporting of GHCN stations, a problem we’ve also seen with GISS. Both GISS and CRU use GHCN station data which are received via CLIMAT reports. Some countries report better than others, some update quickly, some take weeks or months to report in to NOAA/NCDC who manage GHCN.
The data trickle-in problem can have effects on determining the global temperature and making pronouncements about it. What might be a record month at the time of the announcement may not be a few months later when all of the surface data is in. It might be valuable to go back and look at such claims later to see how much monthly temperature values quoted in news reports of the past have shifted in the present.
More on CLIMAT reports here in the WMO technical manual.
UPDATE: For more on the continually shifting data issue, see this WUWT post from John Goetz on what he sees in the GISS surface temperature record:
http://wattsupwiththat.com/2008/04/08/rewriting-history-time-and-time-again/
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Am I being overly cynical in noting that:
Sep 10th, 2010: January 2010 anomaly was 0.707 °C
helps them come up with new “it’s been a record month” regularly
Jan 30th, 2011: January 2010 anomaly is now 0.675 °C
lowers the bar for the next set of figures to be “it’s been a record month”?
Maybe I am, BUT how many times do these type of things happen in reverse? In a random universe the adjustments should be 50:50 up vs down (I would guess as a layman).
I have a suggestion, perhaps it’s just me, that far more errors and corrections occur in the direction that aid the ‘panicists’ (if I am to be a denier, they get to be ‘panicists’).
Every time there is a change made in the numbers, there ought to be a just as easy to access justification of the change. The climatologists long ago forfeited the right to automatic trust in their competence or honesty.
IMHO
Surely this should be done electronically now? The recording is taken and sent to a satellite. All the attendee would have to do is ensure that the recording station has a fresh battery in it every now and then – or even run it off solar. With instant reporting we’d have a better idea of weather/climate.
Sigh.
I keep harping on about the poor quality of the data, the fact it keeps changing doesn’t exactly help their cause.
The problem with GISS and with CRU series is that, as a result of these adjustments to trailing data – whether it’s late station reporting or it’s manual manipulation, it matters not – is that we are effectively perpetually on the crest of “unprecedented high temperatures”, which always facilitate alarming reports.
That these alarming reports are nullified, month-on-month, would not be an issue except that those reports are only superseded by the next month’s “unprecedented high temperature” reports.
It is this publicity trick of press releases and retrospective adjustments that allows even a flat temperature trend to be perceived, by all but the most diligent analysts, as an ever-upward trend.
I had to visit John’s blog to figure out the graph (coffee hadn’t kicked in yet). the caption there is helpful – “Monthly Temperature values for global temperature change on a regular basis.”
Each line in the graph links the monthly anomaly as of some reporting date. Hence the September 2010 line has temps from January to July, the late January 2011 line is the only one to include December.
All in all, it’s another reason to rely on the satellite temps.
I thought this was well known.
First?
God forbid if the data for the efficacy and safety of a new drug was collected in this manner.
John,
I too worry about the ‘adjustments’, but I also worry about your ‘5%’.
5% of what?
Is the general trend up to start with and later revised down so that when comparing year on year you will always get an up in temperature? If the figures are continually adjusted up there will come a time when this will be obviously wrong so revision then has to be adjusted down to keep the rise going.
It is no surprise, they have to get the data to fit the latest AGW narative or headlines.
Surely, it is ridiculous to produce temperature figures with an implied accuracy to three decimal places? Does any one reporting these temperatures read the instrument to that level of precision?
“The future is certain; only the past is subject to revision.”
Polish Soviet adage.
Don says:
January 31, 2011 at 5:00 am
God forbid if the data for the efficacy and safety of a new drug was collected in this matter.
Good analogy. Where facts and data are vital, such as medicine and drugs, such latitude isn’t permitted, neither is propaganda. With climate *science*, such abrogation is not unsafe, since there’s nothing at stake either way, being mere voodoo as a consensus.
Like in science fiction, or even fictional novels and films, it is fine to play with the *truth* since it is done for effect. In a court case however, all facts have to be as objectively presented, otherwise cross examinations will arrive at them.
Similarly with the CRU. However, The objection is that they present it as fact and not as fiction
I can understand the data trickle point but if this is truly in play, CRU should wait until all data is in (and analysed) before making any pronouncemnets as to record warming.
Of more concern is the fact the temperature data for the 1930s has been adjusted half a dozen or so times. There can be no good excuse behind all these adjustments.
All in all, it does not lead one to have confidence in the various data sets.
I think that there are strong arguments to scrap the land data set (it is too uncertain and corrupted by unreasoned and probably incorrect adjustments to have much value) and look solely at sea temperature data (the oceans contains about 99% of the total heat energy of the system and these temperatures are most telling about whether there is or is not some form of global warming taking place) and if one must, also at satellite data.
Do CRU still use surface measured data? If so then this shows how antiquated the system is. Since the surface data system is not a complete coverage, with that 2/3 loss of stations in 1990, then these people should shift to satellite data sets. These show a slight global cooling which is not what these people need to show.
On October 4 last year I recorded the Dec 2008 and all 2009 monthly temps for the Western Australia location of Kalgoorlie-Boulder from the GISS database, and checked the figures again the following day …
Recorded Oct 4 2010:
Dec – 24.3
Jan – 27.7
Feb – 25.4
Mar – 22.7
Apr – 18.9
May – 14.3
Jun – 12
Jul – 10.7
Aug -13.8
Sep – 999.9
Oct – 20.8
Nov – 23.5
Dec – 25.8
Recorded Oct 5 2010:
Dec – 24.4
Jan – 27.8
Feb – 25.5
Mar – 22.8
Apr – 19
May – 14.4
Jun – 12.1
Jul – 10.8
Aug – 13.9
Sep – 999.9
Oct – 20.9
Nov – 23.6
Dec – 25.9
Does it really take as long as 23 months to adjust GHCN (and thus GISS) temps, and how come every month needed adjusting by .1 C? The good news is I’ve just checked again and there’s been no change since October 5!
As for that 999.9 missing data error in the GISS records for September 2009 … well, that’s another story: http://www.waclimate.net/giss-adjustments.html
But if you really want to see some fancy temperature adjustments that affected Australian data the previous month, August 2009, check http://www.waclimate.net/bom-bug-temperatures.html
There is a really simple solution to all of this – simply DON’T report the monthly values until all of the data is in! If it takes six months, so be it.
Unfortunately, we live in an era where climate scientists wish to become rock stars and publicity hounds, and never miss a chance to be first with the manic CAGW press release…
All they are saying is that the temperature record today, is not accurate.
Tomorrow, a week from now, a month from now…..
….it will be accurate
I have noticed the same with HadSST (via KNMI website).
Not speaking about GISTEMP:
http://climateaudit.org/2008/04/06/rewriting-history-time-and-time-again/
Those who read George Orwell’s “1984” will understand.
Gendeau says:
January 31, 2011 at 4:36 am
I have a suggestion, perhaps it’s just me, that far more errors and corrections occur in the direction that aid the ‘panicists’ (if I am to be a denier, they get to be ‘panicists’).
===========================
I think ‘panic mongers’ has a better ring to it!
Geoff A
Tony Hansen says:
January 31, 2011 at 5:02 am
John,
> I too worry about the ‘adjustments’, but I also worry about your ’5%’.
5% of what?
Of the anomaly.
$ python
>>> .707 * .95
0.67164999999999997
Approximately – the 5% is rounded up from:
>>> ‘%.2f’ % (100. * (1. – (.675/.707)))
‘4.53’
5% shift in the value.
(0.707-0.675)/0.675 = 4.7% (roughly 5%)
Those with kids can visualise this; you look away for a moment, when you look back the child is sitting innocently next to the wreckage, with eyes like saucers, claiming they didn’t do it.
Why can’t the reporting be automated? This is 2011 for the love off God….