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Guest post in Guardian on microsite influences

Posted on 28 January 2010 by John Cook

After the recent post on microsite influences, I was asked to write on the subject for the Guardian Environment Blog. So here it is, Climate sceptics distract us from the scientific realities of global warming (I didn't write that headline, btw, I suggested "On measuring temperature: how data analysis trumps photographs" but apparently headlines with the phrase "data analysis" just aren't sexy enough). It's basically a less technical version of the original blog post along with an introduction to the concept of microsite influences (while studiously not using the term 'microsite influences' once). The one thing the article does do, I believe, is more succinctly explain how poorly sited weather stations produce a cooler trend:

The cause of this cooling bias appears to have been a change in instruments. In the late 1980s, many sites converted from Cotton Region Shelters (CRS, otherwise known as Stevenson Screens) to electronic Maximum/Minimum Temperature Systems (MMTS). This had two effects. Firstly, MMTS sensors record lower daily maximums compared to their CRS counterparts. So the switch from CRS to MMTS sensors caused a cooling bias in certain stations.
Secondly, the MMTS sensors were attached by cable to an indoor readout device. Limited by cable length, the MMTS weather stations were often located closer to buildings and other artificial sources of heat. This meant most of the stations with the newer MMTS sensors also happened to fall under poorly sited categories. The net result is that poor stations show an overall cooler trend compared with good stations.

Anyway, it's weird excerpting my own writing so go to the Guardian blog to read the full article. I will say one thing - I'm glad I'm not moderating comments on that website. If you consider the behaviour in most online climate discussions, Skeptical Science users are well above the bell curve as far as constructive scientific dialogue goes. Pat yourselves on the back, people!

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Comments 1 to 30:

  1. John, excellent job. Thanks for agreeing to do the article. Education on the science behind climate change is key to helping the general public come to terms with what is happening with AGW and what is expected to happen as AGW ramps up in coming decades. I hope that they ask you back to speak to other issues, and that you accept.

    I've being trying to encourage the editor of one of our provincial newspapers to have a regular column for the purpose of educating the public on climate science and meteorology but to no avail.
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  2. John - I remember reading about a construction of the temperature record using only the sites that WUWT considered "good" - and the conclusion was that the record lined up perfectly with other records. Do you happen to remember the article or have a link?
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    Response: I'm just going from memory here so anyone chime in if I get the details slightly wrong. Early in the history of the surfacestations.org project, one of the users John V took the existing ratings and compared the temperature trend from the best weather stations (rating 1 and 2) to the GISS temperature record. The expectation was that the GISS temp would show a warmer trend as it included all those poorly sited stations besetted with microsite influences. Instead, John V found the good weather stations showed a near identical trend:

    Surfacestations.org GISS Temp vs Ratings 1 and 2 weather stations

    While this result was initially met with dismay, Watts rallied and criticised the result, saying it was made with only a small percentage of stations being rated. I believe some time after this, Anthony Watts made the data on station ratings unavailable to prevent any other data analyses comparing good and bad weather stations - but I'm not sure of the timing of this.

    The next analysis was by NOAA who also published an analysis comparing only the good stations to the total record (NOAA 2009):



    Again, the trends are near identical (you expect some discrepancy as both records cover slightly different regions). Watts criticised this result as a result of homogenisation (data adjustment) of both the good data and the full dataset. That's why Menne 2010 is interesting in that it uses unadjusted data - this is where the cooling bias is revealed.
  3. Congratulations, very prestigious.
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  4. It is -7C, 9:10 in the morning (daylight "savings"), not a cloud in any direction, the sun shining bright and beautifully. I am suppose believe it is warmer than it should be. "Please Sun, do your thing."

    The thought of hundreds of bogus weather stations occupies me after seeing this theme now repeated. It would be nice to know what the measurement accuracy of these systems have on their own. If, for instance, the Earth's temperature was actually rising 0.10 degree per decade, you would need at least +-.05 degrees to even begin to substantial this. And I am not talking about termocouple specs or a thermometer's rating. I am talking about the system as a whole (its total accuracy), and how it is set up. (The graphs of figure 2 in the original article were plotting values to within a tenth of a degree, which implies an accuracy of +-.05. Spectacular, but real?)

    If a pristine mountain peak in the middle of the Pacific makes sense for monitoring CO2, why not apply similar rigor for weather stations? Instead of trying to salvage this data, maybe better to start from scratch. Dont we have 100 years or so to work on this problem? Much cheaper in the end too.

    Aside from issues of accuracy, another important system parameter is repeatability. Repeatibility that can be guaranteed over many years. If you were to simply take the sum of measurements over time from a set of reliable and repeatable instruments, (even if every sensor was buried in a 1 meter cube of cement), this global checksum would tell you something about global warming, because it is the relative change that matters, not the absolute temperature reading.

    My last remark. The continental US doesnt exactly seem like the best location on Earth for monitoring global warming.
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  5. The Australian Bureau of Meteorology has a nice little page of the requirements for Australia's Automatic Weather Stations
    , with details including where they are and site requirements.

    The site lists exactly the things a trained metrologist needs to consider when seeting up any decent temperature monitoring system:
    Resolution, Repeatability, Response time, Drift, Hysteresis, and Linearity.

    It is interesting that in all of this that Watts and the WUWT members seem to forget that America is actually not the world. Australia is of pretty comparable surface area wise to America and if the stations here report a similar warming trend...

    I wait with keen eyes for Watts full analysis!
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  6. yocta
    This is taken from the site
    "Temporal Representativeness
    In addition to difficulties with the correct exposure of instruments, thought has to be given to changes in the long-term exposure of the site. Buildings in close proximity to the instrument enclosure will result in the area of representativeness being reduced.

    For example, when the instrument enclosure at Sydney was installed in 1788, the instruments were representative of a relatively wide area around Sydney. With subsequent construction of high-rise buildings and freeways, climatic and meteorological conditions only 50m from the site are now significantly different to those at the site.

    It is important that the station be inspected regularly and any changes in the siting are properly documented."

    1788?

    Aside from the site, what about technology? Was there even a universal standard set of measurements in 1788?

    I must be going nuts, or is it the CO2?
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  7. RSVP, if its winter where you are, then why are you surprised that the temperature is -7 degrees? Here in Australia most of the country has had temperatures at least +2 to +3 degrees C above average for the last 3 months (Adelaide temperatures for November were more than 5 degrees above average), & AMSU-A shows global January 2009 temperatures to be more than +0.2 degrees above those of 2009-your little corner of the world clearly doesn't represent the world entire.
    Also, I don't believe we have 100 years to fix the problem. Satellite & surface temperatures are in agreement-+0.16 degrees per decade since 1979. As we don't know for certain just how had the impacts of future rises are going to be, I think it would be irresponsible to wait 100 years to "double check". If we don't take serious action within the next 20-30 years, I believe it will be too late to avert a truly catastrophic rise in temperatures. The fact is that, had we listened to the scientists 20 years ago, instead of letting the fossil fuel industry have its way, CO2 mitigation would have been a *hell* of a lot cheaper!
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  8. Oh get real RSVP, do you honestly think that our researchers are so thick that they haven't considered everything you've mentioned, & account for it in their calculations? What is of concern is the warming which has occurred in the last 60 years, which has been measured by suitably reliable measuring stations. Seriously, I really don't know why you're so keen to make excuses for the "head-in-the-sand" approach taken by the Denialist Cult.
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  9. Congratulations, John. I very much liked your article, sounds very natural and it's easy to follow, well fitted to the general audience. It highlights the recurrent skeptical strateggy of arguing with insinuations instead of with actual analysis. It's much quicker and they can produce many more (flawed) arguments, while real scientists spend their time in the (much more time-demanding) real analysis (to be published once the flawed conclussion has already spread out). This is the standard style of Climate Audit, for example. As Winston Churchill said, ‘A lie gets halfway around the world before the truth has a chance to get its pants on’. People must learn to discern what the real scope and implications of a discovery is. Eg. "I discovered a handful of trees crowded together in northern Siberia with a divergence problem". Does it prove that all reconstructions of global temperature over the past 1,000 years are wrong? You don't need a leading scientist doing the hard work to know that insinuations don't prove anyting. Exactly the same with poorly-sited weather stations and Anthony Watts' gratuitous insinuations.
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  10. John - thanks for the response - the NOAA article was the reference I was looking for. I'm just curious - WUWT seems to have devolved into just a load of total nonsense that is obviously nonsense. ClimateAudit.org seems to still have an air of "trying to be somewhat scientific" (when you weed through all the FOIA and BS email analysis) - I'd love to see a more through take-down of his analytical posts....anything in the works there or just too much work for too little benefit?
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  11. Good article. I'm glad the Guardian still publishes reasoned analysis. While I felt it was a fairly intuitive and complete discussion, I'm not sure it's going to satisfy the "photos don't lie" crowd who don't have the time, skill, or inclination to verify the study's conclusions for themselves. Their argument might be "how can we trust any 'analysis' when those photos clearly show urban or microsite warming influences...this just proves it's a scam." Addressing the photo argument more directly would be good - perhaps an intuitive explanation as to why such stations do not add an overall warming bias to the U.S. trend. The recent AMS USHCN version 2 study usefully addresses the Surface Stations argument.

    RSVP: "The continental US doesnt exactly seem like the best location on Earth for monitoring global warming."

    Tell that to the "global warming is a scam" crowd, who have been using relatively cooler U.S. temperatures over the last year or two to argue against global warming. Mr. Watts is a full participant in this line of spin. The U.S. surface record is unreliable, except during the times it shows cooler temperatures.
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  12. Good article John. My view of why the denialists are gaining grounds is that they don't use solid arguments in their argumentation. They make it easy for people to follow their line of "logic". Pictures of "bad" sited temperature instruments seems to do the trick in many peoples mind. We know that the arguments of the denialists are simple, so thats why it's easy for general public to follow their kind of "logic". In the sametime the science is not as easy to follow and easy to misunderstand.

    But instead of trying to stay ground and defend the science, I thing the science should be made easier to follow. The only way, in my opinion, to manage that is to make an offensive, where you make it your goal to make climate science understandable for the general public. We still haven't achieved that goal, or maybe we still haven't set that goal...

    One reason for that, is that the climate science are complicated. But I thing that it's an achievable goal with the right means. I'm not an activist, but I think that by simplifying (in words) the science somehow we're half way there. This should not be the scientists job, and in many cases I don't think that it always lies in their skills to make a simple argument ;) They should be able to continue their work.

    But in some way I know that this is an achievable goal, with the right means.

    Regards,
    Svatli
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  13. There's one thing in this subject that strikes me as obvious, but I haven't seen it so far (not that I've searched much):

    We're not talking about absolute temperatures, but instead they're temperature *anomalies*. If I had a termometer in an oven at 200ºC for the whole century, the anomaly would be zero. So having a termometer in a parking lot, while it yields of course a higher temperature, it does not produce increasingly higher temperatures over the years and decades.

    Am I oversimplifying it?
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  14. RSVP ...

    "If a pristine mountain peak in the middle of the Pacific makes sense for monitoring CO2, why not apply similar rigor for weather stations? Instead of trying to salvage this data, maybe better to start from scratch. Dont we have 100 years or so to work on this problem? Much cheaper in the end too."

    Well, actually, a new temperature monitoring system, designed from the ground up to meet climatology needs, has not only been designed, but deployed.

    It's called the US Climate Reference Network.

    In fact, it's the CRN siting criteria that Anthony Watts is using to "prove" that certain stations in the Historical Climate Network are "bad" - using standards set in the last decade to categorize stations that are decades or a hundred years old.

    One of the results of the Menne 2010 paper is that the several years of USCRN data we have matches the temperatures derived from the historical stations extremely closely. Two separate sets of stations, one set explicitly designed to meet rigorous siting standards and provide optimal spatial coverage. The other a much larger set of stations placed originally to provide data for weather forecasting.

    And they match.

    And as years go on and they continue to match, it will only increase the confidence of the accuracy of data from the historical network of stations (though within science it's already sky-high).

    The historical data has been subject to dozens of tests, and has always passed with flying colors. The only test it hasn't passed is the "I took a photo but did no analysis" test, which is bogus.

    Not only do we not have 100 years to wait, there's no reason in the world to throw out existing, perfectly good, data - except for the politics of delayed action.
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  15. John - I'm sure you are aware that the counter from Watts is that the reason that he wants a fuller sample than that used by Menne before writing it up is because the earliest returns of photos of sites were naturally urban - close to the neighbourhoods of volunteers. I think it is arguable that he and Pielke Snr will get a strikingly different result when they get their turn to use their siting scores with temp data. I guess you didn't mention that because you think it is a weak argument by Watts? I don't think we will have too long to wait to find out.
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  16. Thanks dhogaza for that clarification. Sounds good.
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  17. Mark J @ 15 - re: Watts?Pielke awaited paper, and so science goes, building, or tearing down, based upon past papers. Seems to work not bad eh?
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  18. John Congrats on your Guardian article. I think it is an excellent contribution. You also say "Anyway, it's weird excerpting my own writing" to which I reply, when referencing, always reference the best.

    John
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  19. Alexandre, your reasoning is correct. That and related issues are discussed in the post and comments in the other thread--the one having John's original post, On the reliability of the US Surface Temperature Record.
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  20. I'm curious why these discussions fail to address the US Surface Climate Reference Network?

    An outgrowth of a study conducted in the late 1990's, the USCRN went online in 2003 to address some of the concern about site based bias in measurements.

    More information is available from NOAA.

    http://www.ncdc.noaa.gov/crn/
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  21. padruig, that was just mentioned by dhogaza.
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  22. Yes, I did, but it's nice to have the pointer to the ncdc page ...

    is Menne 2010 the first paper to compare data from the new network with the old, historical weather station network?

    More important, has NOAA photographed all 100+ of the new stations, or not? If so, in color, or black-and-white?

    "John - I'm sure you are aware that the counter from Watts is that the reason that he wants a fuller sample than that used by Menne before writing it up is because the earliest returns of photos of sites were naturally urban - close to the neighbourhoods of volunteers."

    Researchers have previously compared rural with urban stations and have found no significant difference in trend.
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  23. Could anyone provide a pointer to the literature of "data homogenization" as a statistical procedure? I mean the kind of study that would discuss it on its own right, independent of Climate Science.

    I looked hard, but could come up with nothing.

    There is something called data homogenization used in data warehousing, but in the absence of metadata it relies heavily on AI technologies like pattern recognition. It is not meant to be used to produce "objective" datasets, just hints.

    In other words it is woodoo magic, not a tool for science.

    BTW, Menne at al 2010 do depend on data homogenization.

    http://www1.ncdc.noaa.gov/pub/data/ushcn/v2/monthly/menne-etal2010.pdf
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  24. Meanwhile, we are seeing just in the past week significant numbers of record high temperatures at the highest latitudes of the continental US. I guess RSVP must be living in the wrong neighborhood.

    http://mapcenter.hamweather.com/records/7day/us.html?c=maxtemp,mintemp,lowmax,highmin&s=20090913&e=20090913
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  25. RSVP: "It would be nice to know what the measurement accuracy of these systems have on their own. If, for instance, the Earth's temperature was actually rising 0.10 degree per decade, you would need at least +-.05 degrees to even begin to substantial this."

    If the results are obtained using many measurements from a each of a large number of instruments then the overall trend can be found to much higher precision than the accuracy of individual instruments (if there's no systematic bias in the errors, of course, which is the whole point of the article). You could easily see a 0.1°C/decade increase using only a few dozen thermometers which only had a resolution of 1°C using one measurement from each for each of the 3652 or so days in a decade.
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  26. Berényi Péter,
    homogenization of a temperature time serie is not a statistical procedure. If, for example, a sensor is moved downhill you correct for the lapse rate. Homogenization means to take into account all the possible sources of bias one can identify.
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  27. This is off topic but I can't find anyone discussing Susan Solomon's (NASA)new study showing that water vapour is decreasing in the stratosphere.
    She says that water vapour is acting as a negative feedback rather than amplyfiying CO2.
    http://www.guardian.co.uk/environment/2010/jan/29/water-vapour-climate-change
    says no one understands why its decreasing
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  28. Iodolite, Solomon's new stratospheric water vapor paper is discussed at RealClimate.
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  29. I didn't go through the paper accurately yet and maybe i will contradict myself later :). But there are a few things that i feel can already be stressed

    It is not on the water vapour feedback. Indeed, it focuses on the water vapour just in the lower stratosphere; it might have contributed to the slow down of the tropospheric temperature (as opposed to global warming) increse, but it's something related more to interannual/decadal variability than to the long term trend.
    The reason of the sudden drop in year 2000 is not clear. It might be related to the unusual warming of the western pacific ocean and the drop of the tropopause temperature. If this is linked to global warming or it is part of a natural cycle can not yet be assessed.
    As far as i know no one has looked at models behaviour as far as the lower stratospheric humidity is concerned. It's then hard to guess a possible physical mechanism responsible for its reduction and if it's a consequence of the already known physics. Gavin Schmidt at RealClimate promised further analysis, we'd better wait for more insights.

    As is standard practice in science, unless there are evident flaws in a paper (which seemes to be not the case here) it should be carefully evaluated taking the required time. No nails in the coffin nor smooking guns around, just one more little piece of evidence to fit in the global picture.
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  30. Thanks, I'll go do some reading. I have no science background at all so I find reading others comments often increases understanding of what I read. Other times I just get lost.
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