This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
The apparent rise of global average temperatures is actually an illusion due to the urbanization of land around weather stations, the Urban Heat Island effect.
Answer:
Urban Heat Island Effect has been examined quite thoroughly and simply found to have a negligible effect on temperature trends. Real Climate has a detailed discussion of this here. What's more, NASA GISS takes explicit steps in their analysis to remove any such spurious signal by normalizing urban station data trends to the surrounding rural stations. It is a real phenomenon, but it is one climate scientists are well aware of and have taken any required steps to remove its influence from the raw data.
But heavy duty data analysis and statistical processing aside, a little common sense and a couple of pertinent images should put this idea to bed. Here is an image, taken from Astronomy Picture of the Day (a wonderful site, by the way), of the surface of the earth. It is a composite of hundreds of satellite images all taken at night. (The large version is well worth the download time!)
Aside from being very beautiful, it is a perfect indicator of urbanization on earth. As you can see, the greatest urbanization is over the continental United States, Europe, India, Japan, Eastern China and generally coastal South America.
This next image was taken from NASA GISS. It is a global surface temperature anomaly map which shows warming (and infrequently, cooling) by region.
Look at North America, look at Europe, at Asia, Australia, Africa and the Poles and compare them to the urbanization in the image from APOD. There is quite simply no way to discern any correlation whatsoever between urbanization and warming. If the UHI effect were the cause of warming in the globally averaged record, we would see it in this map.
The claim that Global Warming is an artefact of Urban Heat Island Effect is simply an artefact of the Urban Myth Effect.
Addendum: Wikipedia has a very good article on this subject. Among all the interesting details it mentions a few papers that directly discuss efforts to identify and quantify UHI influences on the global temperature trend including this one which would be a good one to cite:
A 2003 paper ("Assessment of urban versus rural in situ surface temperatures in the contiguous United States: No difference found"; J climate; Peterson; 2003) indicates that the effects of the urban heat island may have been overstated, finding that "Contrary to generally accepted wisdom, no statistically significant impact of urbanization could be found in annual temperatures." This was done by using satellite-based night-light detection of urban areas, and more thorough homogenisation of the time series (with corrections, for example, for the tendency of surrounding rural stations to be slightly higher, and thus cooler, than urban areas). As the paper says, if its conclusion is accepted, then it is necessary to "unravel the mystery of how a global temperature time series created partly from urban in situ stations could show no contamination from urban warming." The main conclusion is that micro- and local-scale impacts dominate the meso-scale impact of the urban heat island: many sections of towns may be warmer than rural sites, but meteorological observations are likely to be made in park "cool islands."
If necessary, be sure to refer to all the other ways we know that the global warming trend is not an artefact of anything, it is real.
This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
"Warming Due to Urban Heat Island Effect" was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.
Environment
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Comments
I feel embarrassed for the people who are still buying into this absurd "man-made" global warming propaganda. The evidence disproving it is abundant and far stronger than the "evidence" "proving" people are causing global warming. Do yourself a big favor before you continue to stick your foot in your mouth. Go to "Co2 science dot org".
Posted by: Ed Smith, Palm Springs, CA | November 19, 2008 7:16 PM
Ed, I am familiar with CO2 science. How about sharing something specific that you find particularily convincing.
Posted by: coby | November 19, 2008 7:40 PM
Ed, you can keep your embarrassment for yourself mate, you're gonna need it in truck loads as the coming years unfold and you re-read the pathetic, naive, uneducated posts, typified by the one above, that lie in your past. Do yourself a favour man and at least try to understand how science works. As Coby has requested (and you've notably failed to acknowldege), point out where the CO2 science is in error and only you, in your undoubted genius, have spotted it..... Didn't think so.
Posted by: Matt Bennett | February 22, 2009 10:15 PM
While you're at it, take a break from Real Climate. They've descended into attacking anyone who disagrees with a barrage of pithy comments rather than data sets and validated reconstructions, and more often their links (like the UHI links) don't go anywhere useful, like when they link to Nature, and the link tells you you can't read the article.
Posted by: Sideline Observer | March 3, 2009 8:43 PM
Whups -
[Whups comment was deleted because he insists on posting under different pseudonyms. I might have left it if I had seen Adam's response first!]
That paper is indeed valid. Unfortunately for you, it doesn't say what you think it says. I was going to respond to your comment, but it's been done before, and more thoroughly than I would have, so I'll just link instead. Using that exact paper:
http://www.skepticalscience.com/Does-Urban-Heat-Island-effect-add-to-the-global-warming-trend.html
or a reporter who contacted one of the authors:
http://www.sciencenews.org/view/generic/id/36231/title/Dont_blame_the_cities
Your comment shows the dangers of taking a single sentence fragment from the abstract out of context and using that as the basis of your argument.
And before you reference the Watts Up With That post, he's committing two major errors.
1) The same as you, taking a single statement from the abstract out of context.
2) Comparing apples to oranges in his chart. He compares the temperature in two separate locations as if anyone cares what the difference in actual temperature is between those two locations. We're interested in the trend at each location, NOT the actual difference between the two (it's well established and accounted for that it's a bit warmer in the city center as opposed to the outskirts).
http://wattsupwiththat.com/2009/03/18/finally-an-honest-quantification-of-urban-warming-by-a-major-climate-scientist/
Posted by: Adam | March 18, 2009 4:56 PM
I can see it now;
"Climate change causing urban areas to warm faster than rural areas and even faster than models predicted"
Posted by: Crakar14 | March 18, 2009 8:45 PM
I can see it now;
"Climate change causing urban areas to warm faster than rural areas and even faster than models predicted"
Here is the same story from WUWT;
http://wattsupwiththat.com/2009/03/18/finally-an-honest-quantification-of-urban-warming-by-a-major-climate-scientist/
Posted by: Crakar14 | March 18, 2009 9:17 PM
Coby is suggest you go talk to your buddies at real climate because the british seem to think UHI effect is the real deal.
http://www.telegraph.co.uk/earth/earthnews/5303682/British-cities-could-be-up-to-10C-hotter-than-countryside-by-2100.html
By the way here is an article about the US stations, which clearly shows the telegraph to be right and the real climate boys to be wrong.
http://wattsupwiththat.com/2009/05/10/a-report-on-the-surfacestations-project-with-70-of-the-ushcn-surveyed/
Now only a denier would dispute this data from WUWT do you agree?
Posted by: crakar14 | May 11, 2009 10:12 PM
Hi Crakar,
This is a straw man. No one says that there is no UHI effect. The mistake is assuming that the temperature analyses do not take that effect into account and that the global temperature trend is an artifact of this effect.
I should write a post on that...oh wait. Here we are.
Posted by: coby | May 12, 2009 6:15 AM
Coby,
CRU does not account for UHI, they even say so. They do say that the confidence interval is increased instead. GISS attemps to adjust for UHI but that source is suspect due to lack of quality control and rewriting the historical data. RSS and UAH do not have UHI issues, but then they both show less of a warming trend than GISS or CRU.
The recent satellite based studes have shown that UHI is much larger that previous studies. The Northern China study shows that UHI does have a regional impact, despite what Jones and CRU say. So while not all warming is due to UHI, the surface based temperature records have been shown that some portion of the reported warming can be attributed to UHI.
Turns out that RC was wrong, who knew.
Posted by: Vernon | May 12, 2009 10:10 AM
Coby, it is hard to have a discussion if your going to quit posting. Now I am sure it is not so, but it appears that when you start loosing the debate you quit responding. I figure that you just do not have the time being busy with work and a new baby, congrantulations on that by the way. (Really puts things in prespective when you hold them the first time. For me it was like a punch in the gut to realize I was responsible for another life.) Anyway, your the one that posted the talking points on how to talk to us poor skeptics. If you cannot defend them on your own site, then why not pull down the ones it can be shown are not correct?
Posted by: Vernon | May 12, 2009 10:49 AM
Vernon,
Could you provide a citation for CRU and UHI please, I would like to read that for myself.
Would you mind addressing for me my point about the lack of any correlation to higher anomalies and urbanization as demonstrated by the two images that are (...oops are not! but will be again shortly) in the above post. I have never had any septic address that point and I think it is rather a telling one.
Posted by: coby | May 12, 2009 2:54 PM
Coby,
Try reading Jones et. al. (1990), Assessment of urbanization effects in time series of surface air temperature over land
Which is the basis for not adjusting for UHI effect but rather CRU just increases the error range. However, Ren et. al. (2008) Urbanization Effects on Observed Surface Air Temperature Trends in North China
So now that I have shown where CRU does not adjust for UHI because Jones says there is none. I have also shown where regions (Northern China) were off by 0.4C from what CRU showed. Your strawman argument is a red herring. The UHI introduces a bias which does not show as huge anomalies but continuous warming as shown in the China study. There were not higher anomalies but the unadjusted UHI introduced 61% more warming that was real. (1.16 vs 0.72)
Ok, now that I have addressed your strawman and presented the studies that you should have been aware of, Jone (1990) at least. Are you going to retract your position and admit that current studies show that some of the surface temperature trend is an artifact of UHI?
Or how about some more studies? Zhang et. al. (2008,) The relationship between remotely-sensed surface parameters and urban heat islands in the USA
Or yet some more studies Gutierrez, et. al. (2008) Urban Heat Island effect from Satellite Remote Sensing and Land Surface Modeling
This is significant because in the past it was expected that the UHI would show more at night, which turns out to not be true.
Your point to be addressed was a nice misdirection but an anomaly is the difference between current temperature and the 1951-1980 (GISS) or 1961-1990 (CRU) mean for a station. What is really cool about this is both picked baselines that were during the mid 20th century cooling. The bias for UHI for older cities would have been in place well before instrumented measurements started. So Coby, it is the bias that UHI adds, not sudden high anomalies.
Posted by: Vernon | May 12, 2009 7:41 PM
Just to strengthen Vernon's post
http://static.cbslocal.com/station/wbz/wbz/2009/may/SurfaceStations.pdf
This study shows just how bad the US station data is.
Posted by: crakar14 | May 17, 2009 8:38 PM
I am a data analyst in the health field, and I would call myself critical of the data thus far on CO2 causing global warming. I have not read anything on the AGW side which really convinces me that an increase in CO2 increases heat. They appear very strongly correlated, but the assertion of increased temperature causing CO2 seems stronger to me (at least pre-industrial). I have a real question! The satellite image of deviance from mean temperature appears to suggest strong heating in general globally. But satellite heat imagery is something fairly recent. What does a temperature mean look like for this data? Where did it come from? When I see that Africa is a lot hotter, but is that compared to the mean of that area? or the overall global mean temperature?
After reading the surfacestation project, it does seem that the data is not as strong as it should be. While satellite imagery appears convincing, it is merely a comparison to a relatively small time (if I am reading the imagery right, it's not my field - Sorry!).
Also, with the hockey stick data from tree rings getting called to question about interesting selective data, it calls into question all data. Data integrity is my main job, and it is a VERY big deal. Thanks for any help you can give me on the subject.
Posted by: Paul | September 30, 2009 1:12 PM
This is established physics for 150 years now. I rather doubt that the fact that a "data analyst in the health field" doesn't understand the basic physics behind CO2 warming matters for much.
The fact that water, when saturated with a gas, outgasses when warmed is also basic science, and is something every climate scientist on the planet understands, and is something we know has happened in the past.
However, the oceans aren't saturated with CO2. We're pouring CO2 from fossil fuels in the air and a large portion is currently being *absorbed* by the oceans. We know that not just from basic physical theory, but through measurements. Observations. Data.
This is something else every climate scientist on the planet knows.
Eventually the oceans will reach equilibrium with CO2 in the atmosphere (assuming that at some point we stop increasing its concentration) and at that point, further warming will cause more CO2 to be outgassed.
Not a good thing.
This is something else every climate scientist on the planet knows.
In a sense, we're banking close to 1/2 of the CO2 from burning fossil fuels in the ocean. At some point, the "bank" will start giving us our CO2 back, in the atmosphere, causing further warming.
This is something else every climate scientist on the planet knows.
Posted by: dhogaza | September 30, 2009 2:44 PM
Various teams have worked hard for over a decade to compensate for problems in the raw data. The surface stations hasn't really told us anything new. They've attempted to inventory every weather site in the US through photography but haven't made any attempt whatsoever to actually quantify problems.
On the other hand, the scientists - unlike the amateur photographers - have worked hard to quantify the problems and correct them working exclusively with the data itself (rather than go visit individual stations, which they know vary in quality).
There are all sorts of analytical and statistical methods available for correcting problems in datasets.
The guy running the surface stations project - anthony watts - is a clown. He has a high school education and his only "science" background comes from reading weather forecasts on radio and tv stations.
If you really think this guy has a better handle on the data than the professionals who spend their lives working with it, after having gotten the appropriate educational background in statistics and data analysis in a PhD program, you're nuts.
Have you stopped beating your wife yet? The fact that your treatment of your wife is in question calls into question your treatment of your kids and co-workers.
Posted by: dhogaza | September 30, 2009 2:50 PM
Dogaza,
Here is something that every climate scientist on the planet knows but obviously you dont.
http://www.tech-know.eu/NISubmission/pdf/NI_Climate_Submission.pdf
Pay particular attention to the second graph, now before you start frothing at the mouth have a close look at the source of the graph.
Quote from article
"Secondly and of equal importance is the fact that human activities constitute about 3% of the yearly emissions
total. More than 98% of this total is absorbed within a year (thus contradicting the long residence claim).
Since 1.5% is left over, which is recorded as the
increase of atmospheric CO2, the human contribution is only 3% of this 1.5%. This means that, as a maximum, only some
14 ppmv (parts per million by volume) of the increased
levels of carbon dioxide can be ascribed to human activities, as indicated by figures
provided by the US DOE and IPCC:"
So lets take another look at what you posted shall we?
First we have this "However, the oceans aren't saturated with CO2. We're pouring CO2 from fossil fuels in the air and a large portion is currently being *absorbed* by the oceans. We know that not just from basic physical theory, but through measurements. Observations. Data."
Well as the graph shows through observations and data the oceans absorb 770,000 metric tonnes a year of CO2 which comes from natural sources and only 11,400 from fossil fuels etc. As there is no difference in both types of CO2 (as they all, in the end come from the same place) should we not be worried about the 770,000 metric tonnes also?
You then go on to say "Eventually the oceans will reach equilibrium with CO2 in the atmosphere (assuming that at some point we stop increasing its concentration) and at that point, further warming will cause more CO2 to be outgassed."
The graph shows 11,700 tonnes a year is not absorbed, so lets say we stopped emitting CO2 tomorrow and after a short period of time natural emissions are all there is (lets say 770,000 tonnes worth) and the oceans reach equilibrium.
As CO2 has a very short residence time in the atmosphere as shown by the IPCC graph the CO2 emitted from natural sources will be absorbed quite quickly and therefore in theory CO2 will not rise so where does this extra warming come from?
Posted by: crakar14 | September 30, 2009 8:14 PM
Crakar, honestly you really lack common sense. Humanity is pumping just the right amount of CO2 into the air to account for the additional rise but you say that rise is actually from a coincidental magical unknown source and our CO2 just disappears.
This non-human CO2 rise is a standard and can be found here:
http://scienceblogs.com/illconsidered/2006/03/natural-emissions-dwarf-humans.php
Additional discussion of that inanity is here:
http://scienceblogs.com/illconsidered/2009/06/revisiting_the_source_of_the_o.php
Can you tell us about the author of that PDF and why you rely on him? I have not looked but anyone who thoughtfully denies that humans are causing the CO2 to rise is a crackpot.
Posted by: coby | September 30, 2009 11:49 PM
I stopped reading crakar's link at this pack of lies: "The UN's IPCC bases its dire forecasts on nothing more than computer models that regard the earth as a flat disk bathed in a constant 24 hour haze of sunlight, without north and south poles, without clouds and without any relationship to the real planet we live on."
The author is one Hans Schreuder, his website is I love my carbon dioxide dot com (no, really!)
A quick trawl of ISI WoS under the search terms "Analytical Chemistry" and "Chemistry" in the topic & the author "Schreuder H" gave me plenty of links to one Herman Schreuder but not Hans so I can't make any comment on his publishing history (if he has one). No Schreuder H has published anything with climate as a topic.
His website also neglects to mention his publication record, but does mention that he is a member of MENSA. This I find a little strange.
Posted by: Chris S. | October 1, 2009 1:16 AM
Coby:
How does it feel to be "loosing the debate"?
I hate loosing. The worst is when I loose and then my wife thinks I'm a looser and then I have to worry about the her and the mailman. Its enough to make me loose my mind.
Skip
Posted by: skip | October 1, 2009 7:42 AM
#16 dhogaza >
This is established physics for 150 years now. I rather doubt that the fact that a "data analyst in the health field" doesn't understand the basic physics behind CO2 warming matters for much.
===============
No, it precisely is what matters! In a free land he may make a choice! You can not force him because you know you are right.
Posted by: PaulinMI | October 2, 2009 7:40 PM
Paul,
I have a real question! The satellite image of deviance from mean temperature appears to suggest strong heating in general globally. But satellite heat imagery is something fairly recent. What does a temperature mean look like for this data? Where did it come from? When I see that Africa is a lot hotter, but is that compared to the mean of that area? or the overall global mean temperature?
The temperature anomaly map above compares the temperature in each location to the baseline average for that location. One way you can tell it is local is how red the Arctic region is -- obviously it's not hotter there, the temps have just risen more. For satellites I believe the baseline period is 1979-1999, so an anomaly of zero would be the average temp of that time period. You will sometimes also see monthly anomaly data -- in that case the September anomaly would be the differnce between the current September averagel and the average of all the Septembers in the baseline period. Make sense?
Note that the surface temperature data sets have different baselines than the satellite data sets, so you can't directly compare their numbers as Anthony Watts sometimes does. You can compare their trend slopes, though.
PaulInMI,
Calm down, no one is forcing anyone to do anything. You can believe fairies cause all climate change if you really want, you can even start to claim it or post comments on any blog that will allow it (Coby probably will) telling everyone what you believe, that doesn't mean no one should tell you you're wrong, people are free to tell other people they're wrong and have no idea what they're talking about in a free country.
Posted by: Eric L | October 3, 2009 7:38 PM
I'm not speaking of his freedom to believe that, say, the earth his flat. By "not matters much", I mean that no one in NASA is going to pay any attention to him screaming "the earth is flat" as they prepare to launch their next satellite in orbit. His stupid opinion won't matter much because people will ignore it.
Nor will his ignorance of well-established physics regarding CO2's interaction with long-wave infrared radiation. The fact that a ""data analyst in the health field" is ignorant and publicizes that ignorance on a blog isn't going to change the way physicists think about or do physics.
Posted by: dhogaza | October 3, 2009 9:35 PM
EricL
"Calm down, no one is forcing anyone to do anything. You can believe fairies cause all climate change if you really want, you can even start to claim it or post comments on any blog that will allow it (Coby probably will) telling everyone what you believe, that doesn't mean no one should tell you you're wrong, people are free to tell other people they're wrong and have no idea what they're talking about in a free country."
Exactly, thanks for making the same point and see response to dhogaza.[Not sure where the climate fairies came from?]
dhogaza,
"I'm not speaking of his freedom to believe that, say, the earth his flat. By "not matters much",> . . . . The fact that a "data analyst in the health field" is ignorant and publicizes that ignorance on a blog isn't going to change the way physicists think about or do physics."
Also, exactly, but this is the type of person who can discuss the issue and influence his circle of acquaintances on the subject. He can be convinced because he is able to understand. Most, pathetically, don't have a clue. ie, their eyes glaze over when the subject is discussed.
Posted by: PaulinMI | October 4, 2009 5:31 AM