Another Urban Heat Island Example

I do not claim that urban heat island effects are the only cause of measured surface warming — after all, satellites are largely immune to UHI and have measured a (small) warming trend since they began measuring temperature in 1979.

But I do think that the alarmist efforts to argue that UHI has no substantial, uncorrectable effect on surface temperature measurement is just crazy.  Even if one tries to correct for it, the magnitude can be so substantial (up to 10 degrees or more F) that even a small error in correcting for the effect yields big errors in trying to detect an underlying warming signal.

Just as a quick example, let’s say the urban heat island effect in a city can be up to 10 degrees F.  And, let’s say by some miracle you came up with a reliable approach to correct for 95% of this effect  (and believe me, no one has an approach this good).  This means that there would still be a 0.5F warming bias or error from the UHI effect, an amount roughly of the order of magnitude of the underlying warming signal we are trying to detect (or falsify).

When my son and I ran a couple of transects of the Phoenix area around 10PM one winter evening, we found the city center to be 7 to 10 degrees F warmer than the outlying rural areas.  Anthony Watts did a similar experiment this week in Reno (the similarity is not surprising, since he suggested the experiment to me in the first place).  He too found about a 10 degree F variation.  This experiment was a follow-on to this very complete post showing the range of issues with surface temperature measurement, via one example in Reno.

By the way, in the latter article he had this interesting chart with the potential upward bias added by an instrumentation switch at many weather stations

climate_station_move

This kind of thing happens in the instrumentation world, and is why numbers have to be adjusted from the raw data  (though these adjustments, even if done well, add error, as described above).  What has many skeptics scratching their heads is that despite this upward bias in the instrumentation switch, and the upward bias from many measurement points being near growing urban areas, the GISS and NOAA actually have an increasingly positive adjustment factor for the last couple of decades, not a negative one  (net of red, yellow, and purple lines here).   In other words, the GISS and NOAA adjustment factors imply that there is a net growing cooling bias in the surface temperature record in the last couple of decades that needs to be corrected.  This makes little sense to anyone whose main interest is not pumping up the official numbers to try to validate past catastrophic forecasts.

Update: The NOAA’s adjustment numbers imply a net cooling bias in station locations, but they do have a UHI correction component.  That number is about 0.05C, or 0.03F.  This implies the average urban heat island effect on measurement points over the last 50 years is less than 1/300th of the UHI effect we measured in Reno and Phoenix.  This seems really low, especially once one is familiar with the “body of work” of NOAA measurement stations as surveyed at Anthony’s site.

  • stan

    you got C and F backwards in the update.

  • stan

    Question about the satellite measurements. How were they calibrated? If they used the surface temp record to start out, is there a bias introduced at the start?

  • Jennifer

    “I do not claim that urban heat island effects are the only cause of measured surface warming — after all, satellites are largely immune to UHI and have measured a (small) warming trend since they began measuring temperature in 1979.”

    Largely? I would say entirely. Also, the data from satellites agrees very closely with data from surface measurements. Also, all measurements agree that the greatest warming rate is seen not in areas with large populations but in the Arctic. Also, the oceans are warming, and mountain glaciers are retreating. All of these observations are incompatible with the idea that there is any significant ‘urban heat island’ contribution to the measured global warming.

  • hunter

    Jennifer,
    The oceans are not warming, the Arctic has been cooling, and the correlation between surface and satellite temps is actually a problem for those claiming accuracy of either.
    And by the way, Alaska glaciers added mass this year.
    The breezy way in which AGW promoters and believers blow off data that conflicts with the apocalyptic models would be entertaining if it were not leading to idiotic legislation.

  • Flanagan

    Well, unfortunately all the temperatures anomalies are up since 6 months now. I guess HadCrut, GISS, AMSU, etc. all collaborated to make us “believe” the world is actually warming…

  • Flanagan

    Well, unfortunately all the temperatures anomalies are up since 6 months now. I guess HadCrut, GISS, AMSU, etc. all collaborated to make us “believe” the world is actually warming…

  • Keith Hogan

    Stan asked, “Question about the satellite measurements. How were they calibrated? If they used the surface temp record to start out, is there a bias introduced at the start?”

    I looked this up a while back, and found that the satellites use an on-board heater monitored by redundant high-precision thermistors for a high temperature reading and then look at interstellar space for a low temperature reading. They do this routinely during operation. Unfortunately, the link I had for the document describing this no longer seems active.

  • redneck

    Flanagan,

    Below are the monthly global temperature anomalies from GISS for 2008.

    Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    2008 14 25 62 36 40 29 53 50 49***************

    The numbers indicate that 6 months ago in March the anomaly was 0.62C. For the following 6 months the temperature anomalies are all less than 0.62C. I guess you were mistaken when you included GISS in your group of collaboraters.

  • Demesure

    “Also, all measurements agree that the greatest warming rate is seen not in areas with large populations but in the Arctic. Also, the oceans are warming, and mountain glaciers are retreating. “
    ————————————–
    In “all those observations”, that’s strange you omit to mention global temperature. It must be that it is decreasing over the past 6, 7 years.
    BTW, the oceans are NOT warming, they are cooling according to the high precision Argo boueys array : http://www.npr.org/templates/story/story.php?storyId=88520025

  • Flanagan

    Well, you are right. I was in fact surprised the others temps are increasing since la nina-induced cooling typically lasts for 6 months after it’s over (this would place us in July).

    And global temperatures are increasing, as you can see by performing a least square linear fitting of the global temperatures. And this is, again, surprising as we had a combination of two la ninas and very weak solar activity for 4 years.

  • Jennifer

    hunter: The oceans are not warming, the Arctic has been cooling, and the correlation between surface and satellite temps is actually a problem for those claiming accuracy of either.. ummm… wrong, wrong and what? That last one doesn’t make any sense.

    demesure: if global average temperatures have been dropping as you claim (and 6-7 years, as I’m sure you must know, is too short a time to discern any trend from weather ‘noise’), then that is another observation that demonstrates that urban heat islands cannot be significantly biasing the surface record. If they were, then unless urban areas were shrinking, then the measured temperatures could not be dropping.

  • An Inquirer

    Sometimes I wonder if “Jennifer” reads “his” references. They often do not support “his” contention. The Nature paper referenced was a study for data ending in 2003. The Argo source for non-warming oceans occurs after that. On the second point, I am hesitant to say that the Arctic is cooling given the warming spell that Siberia has experienced in the last couple of years. However, the GHCN data referenced by “Jennifer” stops in 2007, and I imagine that “hunter” was referring to the fact that the Arctic Ocean was much cooler in the fall of 2008 than in 2007. And actually, I am surprised that “Jennifer” doesn’t understand the statement about satellite vs surface measurements. Satellite temperatures do not measure the surface, rather when we see their estimate, it is for the lower troposphere. GISS and HadCrut are largely surface temperatures. A fingerprint of AGW is that tropospheric temperatures are supposed to be rising faster than surface temperatures. (Meanwhile, stratospheric temperatures are supposed to be falling in the AGW fingerprint.)
    And of course measured temperatures could be dropping even with UHI — all that is needed is for other influences on temperatures to be greater than the UHI influence. (BTW, GISS estimated data sets for temperatures do have a slight overall adjustment for UHI. The adjustment could be described as intriguing, bizarre, inconsistent, lacking face validity, and/or creative — but there is a slight adjustment overall.)

  • Jennifer

    ‘An Inquirer’ is getting her knickers in a twist with confusion over the difference between trends and variability. She provides no evidence for ‘cooling’ of oceans since 2003, because there can be no evidence for a long term trend from such a short time scale. And in the Arctic, she thinks that if one season was cooler than one from the previous year, then you can say the Arctic is ‘cooling’? Oh dear. Given that she seems pretty sure of what ‘hunter’ was thinking, perhaps they are the same person using different pseudonyms.

    She also must not be aware that the lower troposphere is expected to be at a similar temperature to the surface, while the upper troposphere is expected to be, and is seen to be, warmer. Try reading this. At least she correctly says that there should be cooling in the stratosphere, which is indeed observed.

  • Jennifer,

    I’d love to see something peer reviewed on the “hot spot” that has also withstood some criticism. Quoting RealClimate as a source is always problematical because they are not a credible source for balanced information. (I’d also cast a jaundiced eye at the other end of the scale, if a link to a website funded by “big oil” was being quoted.) RealClimate is sort of the site you quote when you’re already a true believer and don’t want to think too hard anymore. It’s a shame, because they are very smart guys on that site.

    Further sceptical commentary on the hotspot here:

    http://www.climateaudit.org/?p=3048

  • hunter

    Jennifer,
    Arctic ice is greater this year than last.
    Period.
    Antarctic ice has been at record levels for awhile.
    Period.
    Alaska glaciers, thanks to a very cool summer, did not lose the mass they gained last year.And NASA keep s telling us, by the way, that ice melt was not drivne by warming, but by currents which fluctuate in cycles.
    And the point I made about the alleged correlation between the contaminated surface temps and satellite temps is this:
    It is obvious to any reasonable person that the surface temp data is not reliable. The photographs of a statistically significant number of badly placed weather stations is not something even AGW promoters can explain away with truth.
    So, if satellite temp sensors are in correlation, then the value of the satellite temp data is questionable. This is the GIGO effect in action.
    But GIGO is the basis for selling any apocalypse, so why should selling AGW be any different?
    And by the way, your paranoia about my name and any other poster here is only a reflection of your personal outlook.

  • Jennifer

    Will Nitschke: it’s not clear why you describe realclimate as not being a credible source. Perhaps you have some objective, scientific criterion that shows this, that you’d like to describe? And at the same time, you obviously think that Steve McIntyre is a credible source. Perhaps you could explain why. I quoted you a link to Barry Brooks’ site, anyway, not realclimate. He happened to use a figure quoted also by realclimate, which seems to offend you somehow, but the ultimate source was a peer-reviewed paper. So, if you’d only looked a little further, you could have found what you requested.

    hunter: Arctic ice is greater this year than last. – true, but irrelevant. The magnitude of the long term downward trend is greater if you include this year than if you stop at 2007.

    Antarctic ice has been at record levels for awhile.no.

  • Earle Williams

    Jennifer,

    Nice reversal there:

    Posted by: Jennifer | November 01, 2008 at 02:55 AM
    …6-7 years, as I’m sure you must know, is too short a time to discern any trend from weather ‘noise’

    Posted by: Jennifer | November 04, 2008 at 11:50 AM
    Antarctic ice has been at record levels for awhile. – no.

    So posting a 365-day plot of Antarctic ice area anomaly is sufficient to establish the trend for antarctic ice but 6 -7 years of global mean temperature is insufficient to establish a trend in global temperature? Your logical consistency isn’t even lasting as long as your pseudonym du jour!

    At least do us and your arguments a favor and post the link to the long term antarctic ice anomoly.

    I await your well-reasoned rebuttal. :rolleyes:

  • Jennifer

    Earle, dear, you’re all confused. Somebody claimed that Antarctic ice had been at record levels for a while. I posted a link to the data which shows that currently and for the last several months, Antarctic ice has been around average. No-one said anything about trends down south.

    I await further frustrated cock-waving from you and the other angry little boys.

  • Earle Williams

    Jennifer,

    The only confused one here is you, as you descend into your foul-mouthed name-calling to bolster your failed arguments. It is so reminiscent of the tired hash brought here by Scientist and its many alter egos. In your confusion you must not realize that it is dishonest to post under various pseudonyms and pretend that you are not one and the same person. That dishonesty is clear to everyone who reads these comments. Well, it would seem one person doesn’t get it.

  • Jennifer

    …?

    How about sticking to science instead of paranoid rants?

  • “it’s not clear why you describe realclimate as not being a credible source.”

    It’s a site funded by environmental activists. It’s mission is to push an agenda, unfortunately. It operates on the same level as, say, a Michael Moore documentary. Now I’m not against everything Michael Moore does, and agree with some of the points he makes, but his business is to present a point of view, not provide factual balanced information.

    RealClimate does not tolerate dissenting points of views. It’s comments areas are heavily censored, unlike a site such as this.

    I’ve done reading of the RealClimate site and in my opinion, when I have understood both sides of an issue and the complexities and nuisances involved, I’ve found the RealClimate “view point” disingenuous at best.

    “you obviously think that Steve McIntyre is a credible source.”

    I think his assessments are cautious, and generally fair and balanced. What ‘objective scientific criteria’ do you have for asserting that they are not? Obviously, it’s a judgement call one has to make, based on one’s intelligence.

    “I quoted you a link to Barry Brooks’ site, anyway, not realclimate.”

    Barry Brook’s is not a climatologist. He gets most of his information from RealClimate, just as you do. His funding (i.e., financial dependency) is based on the reality of AGW. He is not interested in being critical of the scientific debate, he would rather there was no sceptical debate, so he is a very poor source to quote.

    “He happened to use a figure quoted also by realclimate, which seems to offend you somehow, but the ultimate source was a peer-reviewed paper. So, if you’d only looked a little further, you could have found what you requested.”

    Peer reviewed papers tend to get spun one way or another to suite an argument, so if you want to be credible, quote the original science, not the opinion of an individual or group with a vested interest. I’m not offended. I’m just pointing out that you don’t need to reinforce the views of the hard core true believers (too much) because they are already convinced. The hard core ‘denyer’ will not change his mind no matter what you write. Anyone who is undecided, though, and may go either way on the issue (such as myself) will write you off as one of the alarmist true believers, as soon as you start sprouting RealClimate propaganda, much the same way as a sceptic about 9/11 would write off an individual quoting Loose Change. OK, RealClimate does have lots of good science discussed on their site, and Loose Change is nonsense. But nonetheless it’s still a site pushing an agenda and not trying to present a balanced view of the science.

  • Jennifer

    Objective scientific criteria for deciding who might be worth listening to – how many climate-related papers have they published in decent journals? As far as I know, Steve McIntyre’s scientific contribution to the field is negligible. All the authors of realclimate have numerous publications.

    His funding (i.e., financial dependency) is based on the reality of AGW – well, then, he’s quite safe. But what makes you think this is so? Is it in his contract? How do you know?

    if you want to be credible, quote the original science, not the opinion of an individual or group with a vested interest – take your own advice and never even think about proposing Steve McIntyre as a useful source on any climate issue.

    Anyone who is undecided, though, and may go either way on the issue (such as myself) will write you off as one of the alarmist true believers, as soon as you start sprouting RealClimate propaganda – I think your claim to be undecided is a lie.

  • “As far as I know, Steve McIntyre’s scientific contribution to the field is negligible. All the authors of realclimate have numerous publications.”

    Now you’re arguing for quantity over quality? He has published in prestigious journals, just as others have. I never said that the guys who run RealClimate aren’t smart guys. In fact I think I did say they were smart guys. (When you start picking at gnats, it weakens, not strengthens, your arguments.)

    “His funding (i.e., financial dependency) is based on the reality of AGW – well, then, he’s quite safe. But what makes you think this is so? Is it in his contract? How do you know?”

    He’s the director of the “Research Institute for Climate Change & Sustainability”.

    “take your own advice and never even think about proposing Steve McIntyre as a useful source on any climate issue.”

    He found GISS US surface temperature anomalies, that then caused a revision of their temperature records. He’s done lots of great work like this. But in your eyes it all counts for nothing because he is on the ‘wrong’ side?

    I realise he is annoying to people who don’t want to tolerate any criticism of AGW, but in the long run the work he does do, makes everyone improve the quality of their own work. If AGW turns out to be a viable theory, he will have made a constructive contribution. No one needs to be afraid of him. Criticism is part of the scientific process. To be scared of it or to try to rubbish it, is to be scared that the truth might be different from something you’ve already preconceived.

    I suspect, but I hope I’m wrong, that you don’t even regularly read what he writes? I think you need to do that, especially if you are determined to express your views, even if it is just a case of ‘know your enemy’. (Although I doubt you or anyone would view things this simplistically.)

    That is what makes sceptics sceptical of people with viewpoints such as yours in the first place. Namely, the fear and tolerance of accepting criticism, especially when it is constructive.

    “I think your claim to be undecided is a lie.”

    Firm assertions without supporting facts, is, I suspect your main problem.

    If you want to save the world, great. But don’t be lazy. Do your own research into the science. Don’t quote propaganda websites. You’ll only convince the uninformed with a strategy like that. Try to understand the issues for yourself, draw your own conclusions, be polite, and especially be patient. Then you can win people over to your point of view. If you take the viewpoint that everyone is a moron except you and you already know all the answers to these difficult questions, you unfortunately alienate people. You actually become someone a sceptical person can point to as a reason why they don’t believe in AGW, and this damages your cause. People should be deciding these issues based on reasoning and science. Not because of fanatical believers on either side of the fence upsetting people and causing them to join one of these camps. Remember, be patient. Be polite. And if you don’t know how to respond to a question posed, don’t get angry and mock that person. Find the answer, reason it out, and patiently explain it to the misinformed person you’re communicating with. Heck, there are lots of misinformed people on both sides of the fence right now. (And BTW, I do believe that CO2 plausibly can cause global warming. But the actual degree of warming is a more complicated issue that is still open to question.)

  • Jennifer

    I’ll ignore your attempts to patronise and suggest that you drop that attitude if you want sensible discussion. If you come across as thoroughly obnoxious, only the equally obnoxious will be keen to be seen to be in agreement with you.

    You asked for an objective scientific way of determining who might be worth listening to about climate. I gave you one. You have yet to tell us the objective scientific criterion for preferring to believe a man who has no track record in publishing any kind of climate science over a bunch of people who are active climate scientists.

    Regarding Barry Brook: you claim “His funding (i.e., financial dependency) is based on the reality of AGW” because “He’s the director of the “Research Institute for Climate Change & Sustainability”. Non sequitur – try again.

    You claim to be ‘undecided’. What exactly are you undecided about? You say “If AGW turns out to be a viable theory”, and then “I do believe that CO2 plausibly can cause global warming”. Looks like you are undecided about what you actually believe.

  • ‘Jennifer’ I can’t really respond to most of your post as it’s logic is either missing or garbled. Your last sentence is correct:

    “Looks like you are undecided about what you actually believe”

    Correct. I cannot find sufficient evidence either way to settle the issue. Probably 5 years more may be needed if dramatic cooling or warming continues. It will take much longer if cooling or warming continues to be flat or gradual. I’m not of the opinion that the absence of the ‘hot spot’ disproves AGW yet. It may be there, but not detectable… yet. One shouldn’t be too quick to dismiss a theory but a credible theory does have to have both logical consistency and be capable of making empirical predictions that turn out to be true.

  • Jennifer

    Well, dear, if you can’t understand what I wrote, the problem is yours, not mine. Try getting an adult to read it through with you. There is quite a difference, you know, between not knowing what to believe, and not knowing what you believe. Why did you say, within one post, “Theory x might not be viable”, and “I think theory x is viable”? Do you understand why that makes you look foolish?

  • jdubya

    I stumbled across this site, obviously from continued linking, etc.
    What caught my eye in this article was Phoenix WRT UHI. I have been a native of this state and am a third generation. I can tell you that there are some interesting anomolies regarding this “oasis” in the middle of the Sonoran Desert.

    Yes, at times in the winter, the night is a bit warmer longer, but usually that seems to die out around December. Interestingly enough, each month does display a sudden change in temperature. We like it that way so don’t plan on retiring here. There is only so much water and too many golf course, haha.

    Anyway, what I wanted to express that in the summer time, it is a bit reversed for certain portions of the city. Phoenix was a farming town since inception until about ten years ago. Yes, you see golf courses, etc., but there was a lot of land dedicated to dairy, farming, and most apparent citrus. After WWII and with the invention of the airconditioner, many began to flock out here. I watched as the citrus fields diminished, leaving a bunch of kids who enjoyed “fruiting cars” in the afternoon to suddenly take up drugs, er, I mean find new avenues of passing time. These new homes were built right on the existing fields, only to have trees moved out of the way for streets, houses, and driveways. You can still see where the old fields are by looking down a street and noticing the arranged trees.

    These neighborhoods still receive water, in the form of monthly irrigation, to flood the yards with what is equivalent to about 90+ inches of water per year. It is a standard fee, and it is environmentally sound: that water percolates into the soil and is purified through the sand enough to allow wells to pull it out and receive minimal treatment prior to human consumption. It pays in two ways: the lush greenery in the central districts of each of the cities in Metro Phx, as well as keeping water close and stored in the ground. Oh, and it is a great place to play kill the carrier (football) or skeetboard on a warm day.

    Again, back to what I was trying to get to, in the summer, when you drive from the newer areas of Phoenix (any area that does not have irrigation canals tied to yards) into the older areas, there is anywhere from a ten to thirty degree drop, Fahrenheit, depending on the month (June is usually the driest so the cooling efficiency is the best). And in the winter, this added moisture to the localized atmosphere has caused inversions and once in a while a bit of fog.

    I bring these items up because Phoenix literally is a city formed from the ashes of another civilization. Some of the irrigation networks were built by the Hohokam and are older than 1000 years. We have added to this and engineered a city in the middle of a desert. I think that cities like Phoenix, Tucson, and Las Vegas should be analyzed differently as these were built sans significant water supply and over the course of years had this vital source brought to each in unique ways.

    That’s my bit.

    Great site as well.