This new paper by Dr. Ross McKitrick of the University of Guelph is a comprehensive review of the GHCN surface and sea temperature data set. Unlike many papers (such as the phytoplankton paper in Nature, complete code is made available right from the start, and the data is freely available.
There is a lot here that goes hand in hand with what we have been saying on WUWT and other climate science blogs for months, and this is just a preview of the entire paper.This graph below caught my eye, because it tells one part of the GHCN the story well.
1.2.3. Growing bias toward lower latitudes
The decline in sample has not been spatially uniform. GHCN has progressively lost more and more high latitude sites (e.g. towards the poles) in favour of lower-latitude sites. Other things being equal, this implies less and less data are drawn from remote, cold regions and more from inhabited, warmer regions. As shown in Figure 1-7, mean laititude declined as more stations were added during the 20th century.
Here’s another interesting paragraph:
2.4. Conclusion re. dependence on GHCN
All three major gridded global temperature anomaly products rely exclusively or nearly exclusively on the GHCN archive. Several conclusions follow.
- They are not independent as regards their input data.
- Only if their data processing methods are fundamentally independent can the three series be considered to have any independence at all. Section 4 will show that the data processing methods do not appear to change the end results by much, given the input data.
- Problems with GHCN, such as sampling discontinuities and contamination from urbanization and other forms of land use change, will therefore affect CRU, GISS, and NOAA. Decreasing quality of GHCN data over time implies decreasing quality of CRU, GISS and NOAA data products, and increased reliance on estimated adjustments to rectify climate observations.
From the summary: The quality of data over land, namely the raw temperature data in GHCN, depends on the validity of adjustments for known problems due to urbanization and land-use change. The adequacy of these adjustments has been tested in three different ways, with two of the three finding evidence that they do not suffice to remove warming biases.
The overall conclusion of this report is that there are serious quality problems in the surface temperature data sets that call into question whether the global temperature history, especially over land, can be considered both continuous and precise. Users should be aware of these limitations, especially in policy sensitive applications.
Read the entire preview paper here (PDF), it is well worth your time.
h/t to E.M. Smith
Rational Debate (August 3, 2010 at 1:25 pm)
“…since temps are measured in terms of anomalies, and supposedly the higher latitudes are warming faster than the lower latitudes, removing higher latitude sites would actually result in lower anomalies rather than higher ones…”
High latitudes show greater extremes of temperature and show greater warming or cooling (anomalies) than lower latitudes. +/-5C is usual at stations in the Arctic, but much less at lower latitudes. This shows up well in this graph of GIStemp latitude bands: http://diggingintheclay.files.wordpress.com/2010/07/latitude-bands.png
Basically in answer to this question:
http://diggingintheclay.wordpress.com/2010/07/14/are-all-anomalies-created-equal/ – no they are not – analysis and posting are still a work in progress 😉
Rational Debate (August 3, 2010 at 1:25 pm)
It is late here, I am tired and I misread your comment – yes to what you are saying, but…. and it is a big ‘but’.
Imagine that the high latitudes are present during colder times and the move to warmer times – that means large cold then warm anomalies, then they are progressively lost as we enter a period which may be starting to cool off, so the less extreme (cooler) anomalies at the lower latitudes then predominate. It is a bit tenuous, but it could matter, particularly if the lower latitude stations are biased by UHI (which ‘is worse than we thought’).
I mentioned this on a thread a few days ago and didn’t get any response. It was a bit off-topic for that thread. But, more on topic for this thread.
Has anybody seen any discussion on how the response time of modern electronic temperature sensors might affect the comparison of the modern temperature record with the past record? I seems a faster responding instrument would record higher peaks when a puff of hot air moved passed the station from some artificial source, like pavement, plowed field, jet engine exhaust, etc., compared to a slower responding instrument, like a mercury thermometer. This could be a source of significant upwards bias.
John Finn says:
August 3, 2010 at 10:38 am
Have you ever actually been to Aldergrove airport?
I have & for an airport site it’s not too bad, it’s actually quite rural
54.656422,-6.217589
DaveE.
Forgot to mention…
The measurement site is in the RAF portion of the airport which is well separated from the main airport.
DaveE.
Mike,
I feel the situation is much worse than you suggest. Read page 11 of this document
http://www.srh.noaa.gov/ohx/dad/coop/EQUIPMENT.pdf
Temperatures are now measured to 0.1 deg but recorded to 1.0 deg. What nonsense to suggest fractions of a degree in global temp changes !
[REPLY – “Oversampling” will do it. For example, a million die rolls should yield just about a 3.5 average. (Having said that, I don’t much trust the current adjustments) ~ Evan.]
Peter Stroud says:
August 3, 2010 at 4:09 am (Edit)
“An excellent paper that should be read by all IPCC sponsored scientists. One thing puzzles me though. On page 11 we see the percentage GHCN stations located at airports from 1890 – 2009. But according to WikiAnswers the first airport was built in 1909, College Park Maryland.”
Wikianswers only considers airports as those servicing heavier than air aircraft, and only considers those locations specifically built for powered aircraft operations, rather than pastureland with weatherstations that was used for aircraft prior to 1909 (since the powered aircraft was first flown in 1902, and individuals had been attempting for years prior to that). GHCN includes a number of airfields which originally belonged to the Army Signal Corps for their balloon operations, and other balloon operations run in other countries by their military organizations. A balloon is an aircraft, even if Wikianswers doesn’t think so.
Oh…
Anther point is, it’s quite close to the moderating influence of the leoch. (Lake).
DaveE.
[i]Vince Whirlwind says: ……
That’s the funniest thing I’ve read for a while. Thank god we have professors of economics to explain science to us.[/i]
Where were you when the wolf-in-sheep-coat “scientists” from CRU and Goddard tried to explain science to us?
Verity Jones says:
August 3, 2010 at 4:37 pm
……Basically in answer to this question:
http://diggingintheclay.wordpress.com/2010/07/14/are-all-anomalies-created-equal/ – no they are not – analysis and posting are still a work in progress 😉
____________________________________________________________________
Verity,
If I click on the (thread here) in this sentence it gives a no access are you lost? statement
“This was a response to a blog comment (thread here) about GIStemp and the calculation of global average temperatures, er, anomalies. “
Otherwise you make some very good points. I have looked at the GISS data for areas in my state and the shape of the trends are all over the place: straight line up trend, straight line down trend, sine waves with no trend,up trend, & down trend and two flat trend lines at different levels. So how the heck do you use the anomaly information from those different types of trends to “adjust ” anything??
—
At 10:25 AM on 3 August, Gail Combs had written:
“Dr. McKitrick may want to add a glossary. Otherwise use the WUWT glossary (on to tool bar) here.”
Not having been aware of the glossary maintained by Mr. Watts and his associates on this site, I had used a search engine to seek the meaning of “GHCN” on the Web at large.
Naturally, “Wiki-bloody-pedia” came up, and strictly to find out what the Flim-Flam squad has been doing over there, I checked out their page for the Global Historical Climatology Network.
Has anyone an opinion of when that page should be edited to incorporate the results of Dr. McKitrick’s paper? In order to give the warmists a bit more agita and to help the millions of search engine users gain a more accurate appreciation of the validity of the information provided by the GHCN (because the search engines seem very reliably to steer preferentially to that most malevolently prejudiced site), the findings of Dr. McKitrick’s study need to show up there as balancing information.
Certainly, we can’t count on the cabal of Cargo Cult Science peddlers dominating Wikipedia to provide such balance.
—
re: Gavin (not Schimidt) says: August 3, 2010 at 6:45 pm
[i]Vince Whirlwind says: ……
That’s the funniest thing I’ve read for a while. Thank god we have professors of economics to explain science to us.[/i]
:::::::::::::::::::::::::::::::::::::
Hi Gavin,
Just an aside, but you’ve got to use carets (e.g, greater than and less than symbols), not brackets to get the html code to work.
Ross,
Looking at your chart for GHCN adjustments
V2mean.adj is a Change File. It must be added to V2.mean and then you have to
replace the lines that are duplicated.
Looking through the code and comparing your results to other results it appears
you may have just assumed that GHCNV2.adj was a stand alone file. It’s not.
you basically have to search through v2mean. find a matching line in v2.mean.adj
and replace the line in v2.mean with the line from v2.mean.adj. Not clear that you did that. if you did, my bad
Further v2.mean.adj also has some anomalous records, at least by my accounting.
Some of the changes in v2.mean/adj do not have corresponding lines in v2.mean
and there are some( a handful) of duplicate records ( not the same as duplicate stations)
Just checking. I’ll double check chad’s code, but you might want to ask him how he combined v2.mean and v2.mean.adj
Bernie says:
In Ross’s paper he makes generous statements about and includes some of the contributions of well known temp mavens – what I termed Serious Amateurs with Strong Data Analysis Skills or more neutrally Independent Researchers. But he refers to them as bloggers. I feel “bloggers” diminishes the substance of their contributions and suggested that he come up with a less pejorative label. However, this is only my opinion and I would be interested in how others feel
Bernie: On my site I have specifically laid out my interests. Among them is that I felt my role was to plough the field rapidly ahead of others, and if I turned up things of interest, I would be very happy being a ‘footnote” in there published papers. In my opinion, that I’m a “link” and not just a footnote is something of “high praise”. So don’t worry about the “slight” of being called a “blogger”, for to me it is no slight. It is the truth and “The Truth just is. -E.M.Smith” and I am honored to be outside the “peer” system as the emails of “ClimateGate” have shown it to be. There can not be any higher praise than to say “He is not one of them”, at least in “my book”.
Rich Matarese says:
August 3, 2010 at 7:30 pm
Not having been aware of the glossary maintained by Mr. Watts and his associates on this site, I had used a search engine to seek the meaning of “GHCN” on the Web at large.
Naturally, “Wiki-bloody-pedia” came up,….
Has anyone an opinion of when that page should be edited to incorporate the results of Dr. McKitrick’s paper? In order to give the warmists a bit more agita and to help the millions of search engine users gain a more accurate appreciation of the validity of the information provided ….
__________________________________________________________
Unfortunately it will not “stick” thanks to Connolley who is dedicated to maintaining the CAGW propaganda at Wikipoo.
—
At 9:44 PM on 3 August, Gail Combs had replied to my query about editing the “Wiki-bloody-pedia” entry on the Global Historical Climatology Network to reflect the findings reported in the preliminary draft of Dr. McKitrick’s paper presently under discussion, writing:
“Unfortunately it will not “stick” thanks to Connolley, who is dedicated to maintaining the CAGW propaganda at Wikipoo.”
I was aware of the activities of Mr. Connolley and the rest of the Wikipedia Ministry of Truth.
I would advise all and sundry that atheromatous cardiovascular disease is, in considerable part, an inflammatory phenomenon which can be exacerbated by emotional stress.
Not that I would wish Mr. Connolley and his co-religionists to come precipitously to something fatal in the way of a cardiac arrhythmia or myocardial infarction, but every little bit of irritation that might be imposed upon these creatures would, ceteris paribus, help to occupy them with stimuli conducive to an outcome beneficial to the well-being of the human race at large.
Is the Italian slang term “agita” not fully understood?
—
@Mike G: I often use “resounding silence” to mean I’m on to something. It usually means nobody has thought about it. That was my response to your point. “Gee… that’s interesting. Probably something to it. I have no idea what to say as it’s a new idea to me. Hmmm…”
Watch for the “negative space” of things. It’s a great forensic tool…
Dr A Burns says:
I feel the situation is much worse than you suggest. Read page 11 of this document
http://www.srh.noaa.gov/ohx/dad/coop/EQUIPMENT.pdf
Temperatures are now measured to 0.1 deg but recorded to 1.0 deg. What nonsense to suggest fractions of a degree in global temp changes !
[REPLY – “Oversampling” will do it. For example, a million die rolls should yield just about a 3.5 average. (Having said that, I don’t much trust the current adjustments) ~ Evan.]
At the risk of igniting yet another precision firestorm: Oversampling of A Thing works, but sampling of many divergent things is NOT oversampling. Measruring A place at A time 10,000 times is NOT the same as measuring 10,000 time/place sets and averaging them. The first is oversampling, the latter is delusional.
@Steven Mosher:
You sure about that “add them together” angle?
From: ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/v2/v2.temperature.readme
That sure looks to me like they are stand alone versions. Also the v2.mean.Z size is 12016 KB while the v1.mean.adj.Z size is 8672 KB which implies to me a near parity, not just a few updates to be glued on.
I can download the data and look at it, but I’m pretty sure it’s a stand alone set.
I would urge all readers to send a link to this page to their elected representatives along with a strongly worded “suggestion” that they get off their duffs and kill this AGW foolishness immediately. Come to think of it, send it to your local paper too [with appropriate commentary].
Nick Stokes (August 3, 2010 at 6:42 am)
Sorry, only just spotted your comment Nick.
“Zeke showed that a reconstruction using the adjusted file gave very similar results to the GHCN unadjusted.”
That does not surprise me in the least. I have been following the analyses that you and others have been doing. Re the adjustments – they seem to be so finely balanced that the there is little change overall. At least that is what I have been seeing in GIStemp. It is not just the adjustment, but the spatial and temporal balance of the adjustments. At a local level they can have a big effect but scaled up and averaged over the globe the differences are very small ~0.1 deg of trend. I think it is to do with homogenisation tending to ‘average things’ such that in a location one station may be ‘warmed’ and another ‘cooled’ so that all have a similar trend.
I posted a version of this at tAV earlier – looking at the nightlights radiance adjustment implemented in January. http://diggingintheclay.wordpress.com/2010/07/10/gistemp-plus-ca-change-plus-cest-la-meme-chose/
It caused very little overall difference, and looking at how it affected the data by lattitude there were reasonable differences in the latitude bands, but they cancelled each other out at global level. Dig down to country level, even grid square location and individual station level and there are very major changes. This is something we all need to look into more.
Gail Combs (August 3, 2010 at 7:17 pm)
Thanks for the heads up – link now fixed. And yes the adjustment process is a source of no end of wonder to me (and others).
Peter O’Neill has done some very detailed posts explaining it: http://oneillp.wordpress.com/
In other words:
The surface temp. data sets are far too biased and limited to draw any dire conclusions about long term climate.
Now can we get back to real problems and just ignore the likes of Gore, Hansen, Schmidt and Jones?
David A. Evans says:
August 3, 2010 at 5:26 pm
John Finn says:
August 3, 2010 at 10:38 am
Have you ever actually been to Aldergrove airport?
Yes.
I have & for an airport site it’s not too bad, it’s actually quite rural
But there are still planes and tarmac. Things which weren’t around in 1880. Aldergrove should have been more affected than most other places by the UH influence over the past 50 to 100 years. If you read up on the UH response to urbanisation the effect is logarithmic, i.e. the transition from rural to semi-rural has a far bigger effect than, say, increased urbanisation in a major city.
In other words – the TREND should have been greater. The trend is actually greater at Armagh.
E.M.Smith says:
August 3, 2010 at 11:32 am
The effect varies a bit with wind speed, but one of the problems is that large airports are near large urban centers, so you often can simply have the city UHI blowing over the airport, so it’s both wind speed AND direction (and what’s nearby…) that matters most. But overall, yes, they are hot places. You can do A/B/ compares via Wunderground and see it for yourself some times.
I am not questioning the UH effect. I know UH exists. I’ve experienced it many times. I am, though, questioning it’s effect on the calculated trend(s). A major urban area will generally have higher temperatures than a nearby rural area – especially when it’s very hot or very cold. But does the urban area have a greater warming trend over time? Do airports have a greater warming trend than nearby rural locations? There doesn’t appear to be much evidence that they do.
Raw temperatures are not really relevant. It’s the trend that matters.
—
At 12:52 AM on 4 August, Jeff B. writes:
“Now can we get back to real problems and just ignore the likes of Gore, Hansen, Schmidt and Jones?”
To a considerable extent, “the likes of Gore, Hansen, Schmidt and Jones are the real problems we’re confronting today, by which I mean creatures without conscience or consequence fixated upon exerting control over their fellow human beings out of megalomania and a strange, sick sense of their own “entitlement” to rule those whom they arrogantly consider to be their inferiors.
That, by the bye, emphatically includes us “skeptics.”
Haven’t you noticed their attitude toward us? How dare we question them, dispute them, ridicule them, and treat them with the scorn they have so richly earned?
Heavens, don’t us peasants know our place?
Let us of course add to that listing of warmist charlatans their political allies in both wings of America’s sordid, permanently incumbent Boot-On-Your-Neck Party (especially the National Socialist faction, which we’re no longer calling “Democrat”).
Whenever our President-With-An-Asterisk addresses the American people, do you note that he holds his head as if somebody had smeared his upper lip with a particularly noisome dollop of fresh stool?
Call me a teabagger, but I get the impression that – despite his fervent desire to spread our wealth around – he doesn’t like us very much at all.
—
EM.
It’s a change file. Regardless, nobody uses it.