Talk:Urban heat island

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(New talk at bottom)

[edit] Old

A page in sore need of attention William M. Connolley 22:03 Feb 12, 2003 (UTC)

"the retention of thermal radiation (generally from the sun's infrared rays) absorbed during the day from sunlight" is wrong: solar radiation is mostly non-IR; etc etc. The existing explanation was confused, and I've re-written it, but it needs more work.

"some scientists say" -> "some say" before link to sepp. Etc.

I'd like to move this article from urban heat island effect to urban heat island. Then, discuss what an urban heat island is, giving 2 examples. Also, how many there are and/or how much warmer they are than the surrounding are. Plus, whether and/or how much they have been getting warmer over the decades.

Then, report what scientists say about what causes these "heat islands".

Finally, get into the controversial stuff: the relevance of urban heat islands to the global warming theory. Some say this, some say that.

--Uncle Ed

Heat islands effects the global climate directly by increased use of air conditioning, etc
Use of cars, etc, does contribute to urban heat islands, but not as much as the albedo difference

I've (William M. Connolley 13:34 Feb 14, 2003 (UTC)) added some stuff, derived from IPCC, about why the UHI impact is small. If googling turns up lots of articles saying the reverse, put links to them here, and we can either add them to the UHI page (if they make sense) or add rebutals (if they don't).

BTW, I now think the very last para looks unconfortable.

Well, the section relating UHI to GW is more than half of the article. I hope that's not too much.

Also, I guess I better check all those half-remembered sources again. If I recall correctly, the heat increase in urban areas is about 0.9C per century (as today's article states) -- but the trend in rural areas is much, much less; and the trend in uninhabited areas is basically flat, i.e., no increase.

Last week I visited a site which draws trend lines and calculates the R-squared values for a linear regression analysis of temperature readings. You pick a grid square by latitute and longitude, and you get a graph of the trend. Guess what? Wyoming isn't getting warmer. Georgia is hardly warming at all (negligible). But New York is warming rapidly! Hmm, these three statistics support my point, i.e., that most "global warming" is really just urban warming, and Kyoto advocates are confusing the urban heat island effect with real global warming. --Uncle Ed 17:20 Feb 14, 2003 (UTC)

Nope. Picking a few grid squares at random is anecdotal evidence. I think finding the 1/2 remembered sources would be a good idea... (William M. Connolley 22:50 Feb 14, 2003 (UTC)).

From the IPCC report, which sites other references that I can list if you like, the urban heat increase for 1950-1998 is 0.1C per decade, or 1.0C per century, as compared to 0.8C for rural areas, and 0.92C overall. This isn't considered statistically significant in the IPCC report. Graft

I've (William M. Connolley 22:50 Feb 14, 2003 (UTC)) changed "first found in the mid-1800's in the US" to "first found in the 1800's". There was no source for that,and googling says early 1800's in the UK: http://www.suite101.com/article.cfm/weather/53429 or http://216.239.57.100/search?q=cache:FRuyjhwGfo4C:geog.tamu.edu/~soma/UHI.ppt+urban+heat+island+1800&hl=en&ie=UTF-8

Good catch, William. Thanks, and have a good weekend. --Uncle Ed 23:02 Feb 14, 2003 (UTC)

I've tried to begin balancing the biased IPCC sources with some objective scientific observations. If we listened only to the IPCC and other United Nations organizations, we might get a false impression.

The UN is biased on Israel: it does not condemn anti-Semitism. The US is biased on human rights. It lets Cuba (the world's biggest prison) onto the commission while voting the USA (where most refugees want to go) off!

Why would a UN-created body like the IPCC be any different? I mean, let's be objective here... okay, at least let's be neutral. --Uncle Ed 16:38, 14 Aug 2003 (UTC)

(William M. Connolley 20:38, 13 Oct 2003 (UTC)) To start, it would be nice if you stopped changing all instances of IPCC into "IPCC, a united nations organisation". Its silly. And can we leave Israel out of GW please? And no, of course, you shouldn't listen to IPCC only: you should read what they say, and if you disagree, you should follow up their references to see if they have misquoted the papers (most unlikely; I know of no examples at all, nor even any accusations) or if you agree with the original papers.

But more substantively: someone (I think Ed) inserted a quote from that well-known totally-objective source co2science, and misattributed it to a scientific paper. This was a fairly crass mistake: scientific papers don't say things like "It is ludicrous to believe that..."

More: the "first found in the 1800's" has now become an (unnamed) midwestern city. Please can whoever added that attribute it? Or I will re-correct, as above.

There is some deeply unconvincing text about "some sci anal" showing the T record depends on closeness to UHI. All unsourced. It should go, unless it can be sourced. Are these unsourced comments the "objective science" Ed mentions above?

I've now (William M. Connolley 11:55, 14 Oct 2003 (UTC)) moved and substantially edited this para, to make the claims "asssertions", etc etc. If anyone can find sources for these various assertions, then of course they should be added and "assertion" changed to "found" or whatever.

I gather you don't consider Co2Science objective.

(WMC) Absolutely

If I misattribute a source as a "scientific paper" and it's really some other sort of document, please correct me.

I will :-)

--Uncle Ed 20:41, 13 Oct 2003 (UTC)

(William M. Connolley 19:56, 25 Oct 2003 (UTC)) Looking over the first few paras I find stuff that looks dodgy. So, to quote:

A heat island is any territory which is consistently hotter than the surrounding area. Weather maps usually show populated areas having hotter temperatures than the surrounding countryside, appearing like "islands" in a cool sea.

I've never seen one such, but perhaps they exist. Anyone got an example?

The urban heat island effect was first described in the 1800s, when it was discovered that a US midwestern city was getting hotter and hotter each year, compared to the farmland around it.

Some while ago I removed this US bit, since google suggested British city and the US bit is unsourced. Anyone know where this little bit of info came from?

Nearly all cities exhibit a heat island effect, particularly in Summer, with several degrees between the center of the city and surrounding fields. The difference in temperature between an inner city and its surrounding suburbs is frequently mentioned in weather reports: e.g., "68 degrees downtown, 64 in the suburbs".

"several degrees", 68 vs 64... are thse just random numbers, or do they have any source at all?

Oh, come on, William! You never heard of "HotLanta"?

See Ed, you *can* source things when someone pushes you: now how about doing it without being pushed, as routine?

And what about your comment pointing out the scientific work using logarithms and trendlines to relate city population to annual temperature increase? --Uncle Ed 15:52, 31 Oct 2003 (UTC)

Pardon?

[edit] Halloween Documents

It has been known for some time that cities are generally warmer than the surrounding, more rural areas. Because of this relative warmth, a city may be referred to as an urban heat island. [1]

The urban heat island phenomenon was first discovered in the early 1800s in London. [2]

Surely "London and surrounding rural areas" :-)

According to satellite readings from NASA, average temperatures in cities and urban areas can range 5 to 10 degrees Fahrenheit hotter than surrounding areas. [3]

[edit] Links

Here Comes Urban Heat -
Urban Heat Island - Dr. Steve Ackerman, University of Wisconsin Cooperative Institute for Meteorological Satellite Studies
Reducing the Urban "Heat Island" Effect

[edit] Urban cooling effect?

The following paragraph presents a POV, in the guise of being "really true":

the heat island effect is primarily due to the difference in heat absorption between the generally dark surfaces of a city - tarmac from roads, etc - and the vegetation that the city/suburbs has replaced (see albedo). These dark surfaces absorb sunlight, heat up, and retain more of this heat than the suburban areas. However, the observations above show otherwise, since the main effect often occurs at night. A contributing factor is the lack of evapotranspiration from vegetation. Finally, hot air from vehicle exhausts and from industry heats up the air further.

I think it would be better to attribute the claims about heat absorption to the scientists (or others) making those claims.

Also, the claim that "observations show otherwise" should also be attributed to its advocates.

In fact, before today's round of edits, it seems that someone was trying to "dispute" the idea that cities are consistently hotter. I guess that's what that 180-year-old observation about 1/3 a degree Fahrenheit of daytime cooling was all about.

Well, everything should be footnoted and attributed. If there are people who insist on believing in GW who want to discount the UHI effect, they have just as much right to their beliefs as the real scientists :-) --Uncle Ed 16:19, 3 Nov 2003 (UTC)

(William M. Connolley 16:25, 3 Nov 2003 (UTC)) This is bizarre: you were totally happy with the para without the leading "It is common to believe that ..." when it asserted as certainty untruths about the UHI. No complaints about attribution then, eh? The observations show otherwise are in the article if you bother to read them - the fact that the heat isalnd is generally largest *after dark* for example.

And now I've just had a chance to read Ed's changes to the article. Ed: you ask for attribution from me, and yet you move and downgrade genuine attributed statements and replace them with completely sourceless stuff that happens to fit your POV: what is your source for:

Nearly all cities exhibit a heat island effect?

particularly in Summer?

In contrast to the modern phenomena of cities which are hotter all day and all night?

If my changes or comments seem bizarre to a practicing scientist, then perhaps we should just revert all my changes until I regain the power of coherent writing :-)

I am determined not to have an edit war on this page, so I'd rather just go back to the previously-acceptable version rather than kick up a fuss. --Uncle Ed 17:49, 3 Nov 2003 (UTC)

(William M. Connolley 20:58, 3 Nov 2003 (UTC)) OK but it really winds me up having you talk about attribution here like some poor wronged innocent and then adding unattributed stuff yourself.

I've done a re-write, rather than reversion, which emphasises the largest-at-night. If anyone can find reliable sources for otherwise, why, please put them in.

Thanks for the rewrite, and sorry about the bizarre, unattributed changes. I'm a poor writer, I admit it. Also, I have trouble writing neutrally about heat islands since I believe that IPCC and other environmental advocates are confounding the UHI effect with general global warming. I think cities are getting warm rapidly, and small towns are getting warm slowly. But I see no statistical evidence that the earth's surface as a whole is getting warm rapidly, whether due to anthropogenic causes or not. If you have proof to the contrary, please write about it for Wikipedia!! --Uncle Ed 14:29, 4 Nov 2003 (UTC)

[edit] Thanks and two suggestions

The claim about the "mistake" in co2science article is quite strained and seems out of place. From earlier comment, the only "mistake" is Connelly's opinion that the Idsos' "reviews" must not provide any info that the article being reviewed does not (overtly?) disclose. [suggestion: prove it's a factual mistake or say that you can't verify the sizes of the towns they identify or drop the point.]

(William M. Connolley 09:41, 26 Jan 2004 (UTC)) Your spelling hasn't improved. The co2science stuff was an unhappy addition by User:Ed Poor - http://en.wikipedia.org/w/wiki.phtml?title=Urban_heat_island&diff=1290018&oldid=1290012 - headed "A journal article sharply contradicts the politically-motivated conclusions of the IPCC". So I added context to it. It might be better removed entirely.

As to co2sciences mistakes, misreporting towns as cities is the most obvious, I'm surprised you missed it.

The IPCC estimate of 20th century effect of urbanization effect on the global surface temperature record was updated in the 2001 WG1 TAR.

Indeed. Thats why the text on the page is quotations from the TAR.

The upper end of the range cited is more than double the figure presented here. [suggestion: replace current treatment with one which reflects most recent assessment, such as: "IPCC cites urbanization effect of up to 0.12°C in the land surface temperature data for 2000.

It would be a good idea to cite the online report at this point.

The urbanization effect on temperature, they conclude, can be trended linearly back to zero in 1900. A co-ordinating lead author for that chapter of the TAR was lead author on a paper that explains the basis for that 0.12°C figure [see Folland et al., Global Temperature Change and its uncertainties since 1861, Geophysical Research Letters 28(13):2621-2624, July 1, 2001]."

This is wikipedia. Edit it as you please.

Your Wikipedia efforts are sincerely appreciated, and my comments reflect nothing but admiration for what you are doing.

Probably a bit over-smarmy (William M. Connolley 09:41, 26 Jan 2004 (UTC))

Steve Schulin

[edit] Reverting Ed

(William M. Connolley 17:25, 12 Jul 2004 (UTC)) Welcome back to climate change, Ed. I've made a poor start though... anyway, too much of what you wrote was (IMHO) bad that I've reverted it rather than changing it line by line. Let me try to justify that:

The urban heat island (UHI) theory states that a populated territory tends to become progressively hotter than the surrounding area.

This is a bad start. UHI is the idea that cities are hotter than their surroundings. This isn't terribly controversial so its a good place to start. But you start off instead defining UHI as the theory that cities get progressively hotter. This *is* controversial, and isn't the usual definition.

What is controversial about these "heat islands" is how much this additional warmth affects the (global) temperature record (see below).

Note that you have removed my "whether" from this sentence. Yours implies that they *are* affecting the record, and all we need to do is work out by how much.

The winter/summer stuff.

I strongly suspect this is actually base climate dependent. For reasons best known to yourself you decided that there was only one report for winter.

Conservationists advocate that...

Supporters of the GW theory maintain either that...

However, GW theory supporters dismiss...

it isn't necessary to write the article in this deliberately provocative way. For you, Peterson must be a raving GW-er. You don't seem to understand the possibility that he may just be a humble scientist doing his research.

Etc etc. But thats enough for now: lets see whether you want to take this seriously or not.

[edit] Relation to Global Warming

This whole section needs a rewrite. It looks like it was cobbled together poorly or hastily. It fails to explain why the various advocates believe that UHI has or has not skewed the temperature record.

(William M. Connolley 21:01, 24 Jul 2004 (UTC)) Good grief! I partially agree. I've stripped qiute a bit from this section that essentially repeated itself.

I'd like to see some assertions by scientists on both sides of this dispute. Like, Joe Blow says it's all hot air because his analysis of rural and remote land-based thermometer records shows very little warming: significantly less than even the most conservative of the IPCC "models". Or, B. Leaver compared rural with urban stations and found that there was no significant difference: cities are NOT warming up faster than the countryside. --Uncle Ed 15:29, 20 Jul 2004 (UTC)

(William M. Connolley 21:01, 24 Jul 2004 (UTC)) Less agreement. What you want is already there: the Peterson study. Perhaps you don't like the answer. I could make it more prominent if its hard to find...

I recall reading an assertion by a climate researcher that the IPCC, et al., have undercompensated for the UHI effect. If I locate a quote and a source for this assertion, will you allow me to put it into the article?

(William M. Connolley 17:18, 6 Aug 2004 (UTC)) Sure, if its reputable. Even if its FS, in a peer-reviewed journal. What *wont* do is some press-conference quote, quoted only in the skeptic press.

Another assertion I remember reading is a study of all land-based thermometer records in California. The 20th century temperature increase these records showed was directly proportional to the size of the community in which the thermometer was placed: remote areas showed no significant warming, rural areas showed slight warming, small towns showed moderate warming, and cities showed just about the same amount of warming predicted by IPCC models for the average of the entire atmosphere. The writer implied that the only way to "account" for the UHI effect is to ignore all but the remote stations' readings.

(William M. Connolley 17:18, 6 Aug 2004 (UTC)) That would be interesting too. My personal opinion is that, for US-based studies, the Peterson study is pretty good. Its recent though, so there has not been a lot of time for others to react. Its odd (don't you think) that people like co2science haven't chosen to review it?

Also, a Wikipedia link I followed to from a pro-IPCC site concedes that satellite and weather balloon readings (a) agree well with each other and (b) show hardly any warming compared to land-based thermometers. If I locate this quote, would you mind letting me place it into the article? --Uncle Ed 12:46, 6 Aug 2004 (UTC)

(William M. Connolley 17:18, 6 Aug 2004 (UTC)) Good reliable stuff is always welcome. But you have to be quite careful about this stuff. In particular, chopping stuff off at 1996/8 because if you go past that the S+C sat record shows warming is distinctly dodgy. S+C often tout the agreement between their record and the balloons but I'm doubtful of that, but not in a way that I can easily put in wiki. If you are really talking about the sat t record, then that page is a more obvious starting point.

(William M. Connolley 17:18, 6 Aug 2004 (UTC)) Rather than having near-edit-wars, there is a lot to be said for discussing stuff we just know will be controversial on the talk pages first.

I have no particular objection to any of your recent reverts. Actually, when you give a _reason_ for a revert, it helps me to rephrase the point I was trying to make. I want Wikipedia's climate articles to stand scientific scrutiny: neither advancing a biased, anti-scientific environmentalist agenda nor advancing a biased, anti-scientific pro-industry agenda. --Uncle Ed 19:01, 6 Aug 2004 (UTC)

[edit] Contamination

Ed Poor: SEPP examined some of Peterson's earlier work, but balanced it against Goodridge.

In 1999, Singer wrote:

It is likely therefore that the surface data are contaminated by the warming effects of "urban heat islands." Some data support this hypothesis [Goodridge, 1996], others do not [Peterson et al., 1999]. [4]

(William M. Connolley 20:59, 6 Aug 2004 (UTC)) The important Peterson paper is from 2003. Note that G1996 isn't referenced.

Well, c'mon, doc, people have only been studying this stuff for 15 years; (research on global warming really started to 'heat up' in 1989, Lindzen says). And the billions of dollars per year America has put into research takes time to generate enough data and analysis to come up with a viable theory.

Has anyone figured out what to do with water vapor and clouds yet? What about soot? And solar variablity or sunspots? And how accurate are thermometers which only have to be good enough for local weather predictions? --Uncle Ed 14:37, 9 Aug 2004 (UTC)

(William M. Connolley 18:56, 9 Aug 2004 (UTC)) Um, those are some big questions. First, I'll stick by my point that P2003 is the one that matters. The abstract of P1999 is:

Using rural/urban land surface classifications derived from maps and satellite observed nighttime surface lights, global mean land surface air temperature time series were created using data from all weather observing stations in a global temperature data base and from rural stations only. The global rural temperature time series and trends are very similar to those derived from the full data set. Therefore, the well-known global temperature time series from in situ stations is not significantly impacted by urban warming.

So really its an earlier and weaker version of P2003. It has been cited 19 times. The Goodridge paper FS puts in opposition isn't a paper - its a letter. It has been cited once.

Meanwhile: water vapour and clouds are in the models. The GHG properties of WV are, AFAIK, preresented well: I've never heard any compliants. The distribution might be open to question. Clouds, of course, are tricky. But there is no reason the uncertainty should be biased towards warm or cold. Almost everyone agrees solar var is small, which is why the clouds-and-cosmic-rays people come in. Thermometers, individually, are accurate enough, probably. You can discuss exposure, drift, etc.

[edit] This and other GW related pages need to be purged of bias.

why the hell am i writing this??? i could just be doing just about anything else right now....

I just wanted to quickly note that this article and other GW articles repeatedly mention the "concensus" view, which amounts to nothing more than the IPCC view, which in turn amounts to nothing more than the view of about one half of the thousands of scientists who were consulted for the IPCC assessment.

Any time someone mentions a "dissenting" viewpoint, it is dismissed with no intellectual justification. A nice example is in this very article. It is mentioned that skeptics claim that UHI may be responsible for a large portion of the warming, BUT THERE IS NO EVIDENCE (?!?) or something to that effect.

There is evidence... tons of evidence, produced by radio sonde balloons and satellites, both of which show UHI to be an enormous and obvious factor in the surface record. Why certain contributors here are so determined to keep readers from hearing about them is beyond me.

It is something for other contributors to watch for. There is an institutional bias in this particular scientific field and everyone should watch for the types of omission and censorship that is almost to be expected. I find it very humorous that there is even mention of "no peer-reviewed papers to support" the skeptics claim. Does anyone wonder why?

Maybe I will contribute some nice quotes from respected climatologists (MIT, etc.) who are explaining the near certainty with which you will be denied grants and publication if you do not "toe the IPCC line".

Readers deserve the full truth, not the IPCC approved truth. That should include mentioning to them that the IPCCs own report omitted the opinions of about half of the contributing scientists.

(William M. Connolley 09:52, 3 Oct 2004 (UTC)) Evidence... please provide it. Remember, peer-reviewed articles trump people sounding off to the press. Your own personal conviction isn't evidence of bias in the article.

[edit] New Study: 2004/11: Parker

(William M. Connolley 18:31, 18 Nov 2004 (UTC)) I'll dump this in here to remind me to read it some time:

Nature 432, 290 (18 November 2004) Climate: Large-scale warming is not urban. DAVID E. PARKER Hadley Centre. Controversy has persisted over the influence of urban warming on reported large-scale surface-air temperature trends. Urban heat islands occur mainly at night and are reduced in windy conditions. Here we show that, globally, temperatures over land have risen as much on windy nights as on calm nights, indicating that the observed overall warming is not a consequence of urban development.

[edit] Utterly Confused

First, this article [Parker] talks about how the UHI is a generally accepted theory.

Then, it talks about how the UHI effect has had no overall effect on temperature measurements (re: global warming).

I can see 4 possibilities:

(1) temperature measurements happen during the time of the day when the UHI effect isn't apperent.

(2) The proportion of temperature measurements within urban areas vs rural areas is so tiny that it doesn't have any effect.

(3) UHI effect does effect temperature measurements, and the conventional wisdom is wrong.

(4) UHI doesn't exist -- sure, some cities are warmer than before, but others are cooler -- random variation.

1 seems extremely unlikely. #2 also seems unlikely. So what is it? #3 or #4?

Hmm, on reflection the language wasn't too clear. The important point is not the absolute temperature but the trends. I've tried to clarify that; tell me if I've succeeded. William M. Connolley 10:52:28, 2005-07-14 (UTC).

I suggest that the Parker paper be copied to this site, which is permitted under fair use, so we can read it. Or give us a link. The Parker paper is a red herring in the Urban Heat Island debate. raylopez99 17:27:99, 2005-10-14 (PST).

Copy it if you like, it will be deleted, of course, because it isn't fair use. You appear, however, to be confessing that you haven't read it, which is why your "red herring" assertion is so badly wrong. William M. Connolley 09:39, 15 October 2005 (UTC)

And now you are an expert on "Fair Use" as well as GW? ROTFL! What is your basis for the lack of fair use assertion? Perhaps you realize that Wikpedia fails the U.S. test for "fair use" because the articles posted therein are NOT intended for scholarly debate? You may be right--you seem to monopolize this board on the issue of global warming and use your incessant bias to censor all other viewpoints. As for the Parker paper, it does not make sense the way it is posted and from reading the abstract. Either UHI exists, or it does not. Which is it? The fact that it cannot be distinquished between windy and non-windy days and nights is a topic completely irrelevant vis-a-vis whether or not UHI exists. raylopez99 11:01.43, 2005-10-17 (PST).

Copying an entire document so it can be read by the public is generally not "fair use". Doesn't take much awareness of the purpose of copyright to understand the large number of situations where "fair use" does not apply. It is also better to protect Wikipedia by avoiding "fair use" usage. (SEWilco 18:25, 17 October 2005 (UTC))

Anyway, your time might be more productively spent in looking for papers which point out problems with Parker's paper. (SEWilco 18:26, 17 October 2005 (UTC))

[Edit conflict] A few years ago a journal publisher was able to successfully sue for copyright infringement because articles which were available in the company library were photocopied and distributed to staff. It's legit to make a copy for personal use, but not to distribute it. Posting the article here would amount to distribution. Guettarda 18:29, 17 October 2005 (UTC)

I am not suggesting the entire Parker paper from Nature be copied and posted here. I am suggesting excerpts that back the claim in the article be copied here. In fact, if you Google the Parker paper you will find 'sound bite' paragraphs lifted from it. I am suggesting somebody lift more than 1 or 2 paragraphs; life a page or two and post it here. I cannot rebut the untruths that Dr. Connolley repeats on this website unless I can read a copy of the Parker paper. And untruths they are. Dr. Connolley (Dr. Bill as I call him at alt.global-warming) is a known proponent of AGW, that humans cause global warming. Nearly all scientists in the GW debate have agendas (me too, though I don't work in the field, thank God). Anybody care to email me the Parker paper? I will rip it to shreds, guaranteed. There are no sacred cows or sure things in science. As a science major I can assure you that. Even Einstein's laws have unexplained anomalies. I am at: raylopez99@yahoo.com raylopez99 00:11.23, 2005-10-18 (PST).

[edit] Diurnal behaviour

We seem to have an incipient disagreement... I've reverted:

Though the UHI is generally most apparent at night, this belies the fact that it is driven by daytime processes. Throughout the daytime, particularly when the skies are free of clouds, urban surfaces are warmed by the the absorption of solar radiation. As described above, the surfaces in the urban areas tend to warm faster than those of the surrounding rural areas. However, as is often the case with daytime heating, this warming also has the effect of generating convective winds within the urban boundary layer. Due to the atmospheric mixing that results, the air temperature UHI is generally minimal or nonexistant during the day, though the surface temperatures can reach extremely high levels.

At night, however, the situation reverses. The absence of solar heating causes the atmospheric convection to decrease, and the urban boundary layer begins to stabilize. If enough stablization occurs, an inversion layer is formed. This traps the urban air near the surface, and allows it to heat from the still-warm urban surfaces. Thus the nighttime UHI is formed.

That text was inconsistent with the text there The explanation for the night-time maximum is that the principal cause of UHI is blocking of "sky view" during cooling: surfaces lose heat at night principally by radiation to the (comparitavely cold) sky, and this is blocked by the building in an urban area.

I don't think the new text works: if convection moves away the daytime heat, then it wouldn't affect the nighttime. If the main forcing is during the day, the main effect would be seen during the day. At the least, that text needs some source.

William M. Connolley 21:33:05, 2005-08-25 (UTC).

Wow, that was quick. I'm new at this (the wiki bit, not the science), so please bear with me.

The basic argument is this - during the day, the sun heats the surface/ground/buildings/etc. The surface tries to heat the air, but the convection/mixing with rural air prevents significant warming. After the sun sets, the air stablizes and can be heated by the ground, which hasn't yet cooled. (While the warm air is more noticeable, the bulk of the heat energy is stored in the ground, due to much higher heat capacities.) Does that make sense?

I will work on finding some sources.

However, I disagree with the statement that the blocking of "sky view" is the principle cause of the UHI. It is certainly one of the causes, but nowhere have I seen it described as the primary reason, including in the sources listed.

--David Streutker 22:39, 25 August 2005 (UTC)

OK, we could do with some sources for the mechanisms. I know what you're saying re convection, but I'm rather doubtful that the (ground-1.5) t diff would really be highest at night from the mechanism you're describing. William M. Connolley 08:58:55, 2005-08-26 (UTC).

I've changed a bit of it and added some sources. I plan to add more soon (in a different section) to help clarify the difference between surface and air temperature UHIs.--David Streutker 03:44, 29 August 2005 (UTC)

[edit] Omaha Shields merge

In my opinion, Omaha Shields should not be merged here. It appears to be both a neologism and original research and should just be deleted rather than being merged here. --Pak21 14:57, 23 June 2006 (UTC)

There is some stuff about weather changes around cities, but I agree, this isn't suitable for merge William M. Connolley 19:30, 25 June 2006 (UTC)

Omaha Shields has now been deleted (via proposed deletion). I have removed the merge tag. Cheers --Pak21 08:22, 29 June 2006 (UTC)

[edit] footnote problem

footnote number 2 is a broken link and i was just wondering if this claim was disputed because as of now it's not really cited.--Dmcheatw 02:14, 17 July 2006 (UTC)

[edit] UHI and global warming

Article says:

Some advocates charge that temperature data from heat islands has been mistakenly used as evidence for the global warming theory.

Yes, and this view needs amplification. The two sides on this issue are:

that the IPCC has compensated for the effect in its analysis of modern warming trends.
that the "compensation" is not transparent (i.e., they didn't say how they compensatad); and that other calculations show that when temperature records affected by UHIE are omitted, global warming is significantly lower than the figures the IPCC uses.

I've tried to add info about this dispute before, but I can't find it this year. Has anyone seen where it's gotten to? --Uncle Ed 13:46, 21 July 2006 (UTC)

[edit] Eds eds

Ed removed Not to be confused with global warming, scientists call this phenomenon the "urban heat island effect, errm, for reasons that are unclear. Many people do confuse the two: making it clear that they are separate seems a good idea.

Ed removed: ...for example, urban and rural trends are very similar. with the comment the POV that urban and rural trends are very similar needs facts and figures which is clear proof that he hasn't bothered to read the article, which lower down says: the trends in urban stations for 1951 to 1989 (0.10°C/decade) are not greatly more than those for all land stations (0.09°C/decade). and simlarly the rural trend is 0.70°C/century from 1880 to 1998, which is actually larger than the full station trend (0.65°C/century)

So I've put them back. Naturally enough, I took out the unpublished tripe from WH, because the published results in the page are better.

William M. Connolley 16:04, 21 July 2006 (UTC)

I think your deletion is an example of "point of view editing". Why not allow the article to be balanced with an opposing POV? The fact that you are a climate modeller yourself (and a Senior Scientific Officer to boot) carries no weight at Wikipedia, you know. --Uncle Ed 17:26, 21 July 2006 (UTC)

I'll leave that for others to decide. As to deletions: do you mean Warwick? Why should his unpublished nonsense be given any weight at all? Why is it any more interesting than my ramblings on my blog on Wegman? [5]

And... are you going to confess that your rm of the urban/rural was a mistake? William M. Connolley 20:44, 21 July 2006 (UTC)

Woo-hoo! A chance to confess ... "Father, forgive me for I have sinned."

Please point out my error more specifically so I can make a suitable apology.

Truely Ed this is absolutely pathetic and amkes me doubt your good faith. The error in question is the one just above... shall I repoeat it, since you seem unable to read it... OK, here we go:

Have you got that now? William M. Connolley 21:28, 26 July 2006 (UTC)

[edit] Rural vs. Urban temperature trends

I already had that, mate. I'm interested in adding the opposing POV that rural trends are significantly higher than urban trends. In California, for example.

Also, Atlanta is 5C hotter than the surrounding area. If that happened in 5 centuries, that would be a 1 degree/century greater urban increase than rural.

And please, spare me the personal remarks like "pathetic" and "good faith". I'm interested in the article. --Uncle Ed 15:24, 27 July 2006 (UTC)

I'm interested in adding the opposing POV that rural trends are significantly higher than urban trends - ah well, nothing like making your biases known. I suppose the actual numbers in the article mean nothing against that? I consequence, I've reverted your changes William M. Connolley 15:55, 27 July 2006 (UTC)

It's not "bias" to add an opposing POV. "Wikipedia's NPOV policy contemplates inclusion of all significant points of view," you know.

As for "actual numbers in the article", they represent one POV (the one you, my notable friend, espouse :-) with which other sources disagree. "Wikipedia's neutral point-of-view (NPOV) policy contemplates inclusion of all significant points of view regarding any subject on which there is division of opinion." --Uncle Ed 20:08, 27 July 2006 (UTC)

Alas, Ed, you tend to see things in terms of fighting POVs, which is very unhelpful for science articles. If you have some other numbers - large scale ones, not just individual places - then please provide them. Otherwise you have nothing. BTW, do you really mean you want rural trends are significantly higher than urban trends? I thought you wanted it the other way round? William M. Connolley 20:18, 27 July 2006 (UTC)

Ever affable, my friend. I appreciate that. Yes, I meant that the POV opposing yours is that rural temperature trends are significantly lower than urban trends. Perhaps you know of a study that compares urban, suburban, rural and "remote" temp data? Be cool . . . --Uncle Ed 21:30, 27 July 2006 (UTC)

Well, there is the Peterson eon, ref'd in the article... though of course that gives the "wrong" result from your POV... :-) William M. Connolley 21:37, 27 July 2006 (UTC)

[edit] Health impacts

I added a paragraph on the health effects of rural vs. urban populations from Johns Hopkins University. 18:57, 2 October 2006 (UTC)

[edit] External Link Removed: Appears to be relevant

Encyclopedia of Earth: Heat island

After visiting site, it does not appear to be spam and offers useful content which appears to be relevant. If there are no objections, I will repost.

Thank you for entering this in the article discussion first.

Regarding the link to eoearth.org, you stated "offers useful content which appears to be relevant". This, however, is not the sole criteria in the WP:EL standard. WP recently has been tightening their external link standards because WP is getting flooded with link spammers who are not simply trying to sell products but are trying to promote their own websitesWikipedia:WikiProject Spam. Here's an extract from this guideline on links to be avoided;

"A website that you own, maintain or are acting as an agent for; even if the guidelines otherwise imply that it should be linked to. This is in line with the conflict of interests guidelines."

Further it states in its guidelines that the following links are to be avoided:

"Links that are added to promote a site..."

"Links to open wikis, except those with a substantial history of stability and a substantial number of editors." eoearth.org is less than 6 months old.

It appears that an individual or group of eoearth.org users have been flooding WP with links to promote this website. In most cases, the only contributions to WP by these users are the addition of these links. In the case of User:KonaScout (who added this link), this user was warned twice prior to cease link spamming eoearth.org by two other editors and the links were removed. If you check his contribution list, the vast majority are simply adding external eoearth.org links. From all appearances, he has stopped his link spamming. Other eoearth.org users likewise have been warned by other editors and most have stopped.

My removal of this link was in accordance with the WP standard. If you still object to its removal and think that its retention should be treated as an exception, this Talk page is the place to do it. If consensus is reached and the link meets WP guidelines, then it can be added.

Again, thanks again for taking the time to write and explain your position. Calltech 17:32, 29 November 2006 (UTC)

[edit] Loads of questions

I'm going to put a big load of text in here - when this is answered please go ahead and delete it, but I've got a bunch of questions first!

there is a risk that the effects of urban sprawl might be misinterpreted as an increase in global temperature. However, the fact that heat islands have such a large effect is, paradoxically, evidence that it is largely absent from the record, otherwise warming would be shown as much larger in the record. The 'heat island' warming does unquestionably affect cities and the people who live in them, but it is not at all clear that it biases trends in historical temperature record: for example, urban and rural trends are very similar.

I'm really sorry - but can someone explain what this means? I get that the trends are the same in city and rural - great. But this 'large effect means it must be absent since we see a small effect' argument seems paradoxical - perhaps we see a small part of the 'large effect'. To give an analogy - maybe we are not seeing a skyscraper being built next to the thermometer - maybe they just paved the road to it. Can someone explain? --Dilaudid 22:48, 20 December 2006 (UTC)

Um, why is this complex? People say, the UHI effect is large. But if it is large, it must be largely absent. I suppose you could invent some magic whereby we only see a small part of a large effect... but why? I don't understand your analogy William M. Connolley 23:38, 20 December 2006 (UTC)

Within the context of global warming analysis, the sentence in question is illogical. Overall temperature change at a location over time is the change in baseline temperature plus a change due to urbanization. If it is known a priori that the baseline temperature has increased (due, say, to global warming), and if the total measured temperature increase is only slightly more than the change in baseline, then it can be concluded that the urban heat effect is slight. However, the question within this section of text is whether temperature measurements taken over time in or near urban centers can be used as evidence for an increase in baseline temperature. The sentence in question simply assumes a positive conclusion to this question, and states the implications in regard to the significance of urban heat effects. SteveH (no username), Thu Dec 28 15:09:22 EST 2006.

The sentence makes no such assumption. What it does point out is that if the assertions of a very large UHI effect were true, then all urban areas would should large warming trends and the overall warming trend would be large. But this is not observed William M. Connolley 20:51, 28 December 2006 (UTC)

In theory, a large UHI effect could be offset to some degree by a decrease in baseline temperature. In order to conclude that ``the overall warming trend would be large`` you need the assumption that baseline temperature has not fallen. But this assumes the conclusion. SteveH (no username) Thu Dec 28 21:50:23 EST 2006

Not if you assume (as many seem to) that the UHI effect is much larger than the background changes William M. Connolley 11:06, 29 December 2006 (UTC)

[edit] United Nation's IPCC

IPCC release your data on how you "compensated" for the UHI.

The IPCC doesn't compensate for anything, because they don't do research. They just compile peer-reviewed research into a comprehensive report. Mishlai 04:24, 21 February 2007 (UTC)

IPCC release your raw data on how you compensated for the UHI, which you later compiled. Frauds.70.176.5.79 04:33, 7 March 2007 (UTC)

You seem to be having a hard time understanding. The IPCC doesn't have the raw data - it is only synthesising the results of other papers. You need to go back to the originals and rant at them instead William M. Connolley 09:22, 7 March 2007 (UTC)

If the IPCC has no raw data, then they have no authority. Thank you for playing the entrapment game. 70.176.5.79 19:34, 16 March 2007 (UTC)

The IPCC has no raw data and does not do its own research. This isn't a secret. The IPCCs authority lies in the quality of its synthesis of published research. Since it does this well, it has a high authority William M. Connolley 22:17, 18 March 2007 (UTC)

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