UHI is alive and well

One of the most ridiculous claims recently related to Menne et al 2010 and my surfacestations project was a claim made by DeSmogBlog (and Huffington Post who carried the story also) is that the “Urban Heat Island Myth is Dead“.

To clarify for these folks: Elvis is dead, UHI is not.

For disbelievers, let’s look at a few cases showing UHI to be alive and well.

CASE 1: I’ve measured it myself, in the city of Reno for example:

The UHI signature of Reno, NV  – Click for larger image

Read the story of how I created this graph here The procedure and raw data is there if you want to check my work.

I chose Reno for two reasons. It was close to me, and it is the centerpiece of a NOAA training manual on how to site weather stations to avoid UHI effects.

CASE 2: NOAA shows their own measurements that mesh well with mine:

To back that up, the NOAA National Weather Service includes the UHI factor in one of it’s training course ( NOAA Professional Competency Unit 6 ) using Reno, NV.

In the PCU6 they were also kind enough to provide a photo essay of their own as well as a graph. You can click the aerial photo to get a Google Earth interactive view of the area. The ASOS USHCN station is right between the runways.


This is NOAA’s graph showing the changes to the official climate record when they made station moves:


Source for 24a and 24b: NOAA Internal Training manual, 2004-2007

Oops, moving the station south caused a cooling. Fixed now, all better.

What is striking about this is that here we have NOAA documenting the effects of an “urban heat bubble” something that DeSmog Blog says ” is dead”, plus we have NOAA documenting a USHCN site with known issues, held up as a bad example for training the operational folks, being used in a case study for the new USHCN2 system.

So if NOAA trains for UHI placement, I’m comfortable in saying that DesmogBlog claims of UHI being “dead” are pure rubbish. But let’s not stop there.

CASE 3: From an embattled scientist.

A paper in JGR that slipped in 2007 without much notice (but known now thanks to Warwick Hughes) is one from Phil Jones, the “former” director of the Hadley Climate Center in the UK. The paper is titled:  Urbanization effects in large-scale temperature records, with an emphasis on China

In it, Jones identifies an urban warming signal in China of 0.1 degrees C per decade.  Or, if you prefer, 1 degree C per century. Not negligible by any means. Here is the abstract:

Global surface temperature trends, based on land and marine data, show warming of about 0.8°C over the last 100 years. This rate of warming is sometimes questioned because of the existence of well-known Urban Heat Islands (UHIs). We show examples of the UHIs at London and Vienna, where city center sites are warmer than surrounding rural locations. Both of these UHIs however do not contribute to warming trends over the 20th century because the influences of the cities on surface temperatures have not changed over this time. In the main part of the paper, for China, we compare a new homogenized station data set with gridded temperature products and attempt to assess possible urban influences using sea surface temperature (SST) data sets for the area east of the Chinese mainland. We show that all the land-based data sets for China agree exceptionally well and that their residual warming compared to the SST series since 1951 is relatively small compared to the large-scale warming. Urban-related warming over China is shown to be about 0.1°C decade−1 over the period 1951–2004, with true climatic warming accounting for 0.81°C over this period.

Even though Jones tries to minimize the UHI effect elsewhere, saying the UHI trends don’t contribute to warming in London and Vienna, what is notable about the paper is that Jones has been minimizing the UHI issues for years and now does an about face on China.

Jones may have tried to hide CRU data, but he’s right about China.

CASE 4: From “The Dog ate My Data” who writes:

The Australian Bureau of Meteorology (BOM) blames Melbourne’s equal warmest overnight temperature of 30.6 degrees, on January 12 on the heat island effect. The previous time the city was that hot overnight was February 1, 1902.

The Age newspaper cites a meteorologist at the bureau, Harvey Stern,

Melbourne recorded its equal warmest overnight temperature, 30.6 degrees, on January 12. The previous time the city was that hot overnight was February 1, 1902.

A meteorologist at the bureau, Harvey Stern, said that Melbourne suffered from a heat island effect, in which a city is warmer than the surrounding countryside.

This was the case especially at night, because of heat stored in bricks and concrete and trapped between close-packed buildings.

I am stunned if that is correct firstly because BOM isn’t blaming Global Warming and secondly that the urban heat island effect directly receives the blame. With faults in the 2007 IPCC’s AR4 now pouring out I guess it is not suprising that attributions of weather events are now, shall we say, possibly becoming more circumspect.

CASE 5: Heatzilla stomps Tokyo

From the website “science of doom” who writes:

New Research from Japan

Detection of urban warming in recent temperature trends in Japan by Fumiaki Fujibe was published in the International Journal of Climatology (2009). It is a very interesting paper which I’ll comment on in this post.

The abstract reads:

The contribution of urban effects on recent temperature trends in Japan was analysed using data at 561 stations for 27 years (March 1979–February 2006). Stations were categorized according to the population density of surrounding few kilometres. There is a warming trend of 0.3–0.4 °C/decade even for stations with low population density (<100 people per square kilometre), indicating that the recent temperature increase is largely contributed by background climatic change. On the other hand, anomalous warming trend is detected for stations with larger population density. Even for only weakly populated sites with population density of 100–300/km2, there is an anomalous trend of 0.03–0.05 °C/decade. This fact suggests that urban warming is detectable not only at large cities but also at slightly urbanized sites in Japan. Copyright, 2008 Royal Meteorological Society.

Why the last 27 years?

The author first compares the temperature over 100 years as measured in Tokyo in the central business district with that in Hachijo Island, 300km south.

Tokyo –               3.1°C rise over 100 years (1906-2006)

Hachijo Island –  0.6°C over the same period

Tokyo vs Hachijo Island, 100 years

This certainly indicates a problem, but to do a thorough study over the last 100 years is impossible because most temperature stations with a long history are in urban areas.

However, at the end of the 1970’s, the Automated Meteorological Data Acquisition System (AMeDAS) was deployed around Japan providing hourly temperature data at 800 stations. The temperature data from these are the basis for the paper. The 27 years coincides with the large temperature rise (see above) of around 0.3-0.4°C globally.

And the IPCC (2007) summarized the northern hemisphere land-based temperature measurements from 1979- 2005 as 0.3°C per decade.

How was Urbanization measured?

The degree of urbanization around each site was calculated from grid data of population and land use, because city populations often used as an index of urban size (Oke, 1973; Karl et al., 1988; Fujibe, 1995) might not be representative of the thermal environment of a site located outside the central area of a city.

What were the Results?

Temperature anomaly against population density, JapanMean temperature anomaly vs population density, Japan

The x-axis, D3, is a measure of population density. T’mean is the change in the mean temperature per decade.

Tmean is the average of all of the hourly temperature measurements, it is not the average of Tmax and Tmin.

Notice the large scatter – this shows why having a large sample is necessary. However, in spite of that, there is a clear trend which demonstrates the UHI effect.

There is large scatter among stations, indicating the dominance of local factors’ characteristic to each station. Nevertheless, there is a positive correlation of 0.455 (Tmean = 0.071 logD3 + 0.262 °C), which is significant at the 1% level, between logD3 and Tmean.

Here’s the data summarized with T’mean as well as the T’max and T’min values. Note that D3 is population per km2 around the point of temperature measurement, and remember that the temperature values are changes per decade:

The effect of UHI demonstrated in various population densitiesThe effect of UHI demonstrated in various population densities

Note that, as observed by many researchers in other regions, especially Roger Pielke Sr, the Tmin values are the most problematic – demonstrating the largest UHI effect. Average temperatures for land-based stations globally are currently calculated from the average of Tmax and Tmin, and in many areas globally it is the Tmin which has shown the largest anomalies. But back to our topic under discussion..

And for those confused about how the Tmean can be lower than the Tmin value in each population category, it is because we are measuring anomalies from decade to decade.

And the graphs showing the temperature anomalies by category (population density):

Dependence of Tmean, Tmax and Tmin on population density for different regions in JapanDependence of Tmean, Tmax and Tmin on population density for different regions in Japan

Quantifying the UHI value

Now the author carries out an interesting step:

As an index of net urban trend, the departure of T from its average for surrounding non-urban stations was used on the assumption that regional warming was locally uniform.

That is, he calculates the temperature deviation in each station in category 3-6 with the locally relevant category 1 and 2 (rural) stations. (There were not enough category 1 stations to do it with just category 1). The calculation takes into account how far away the “rural” stations are, so that more weight is given to closer stations.

Estimate of actual UHI by referencing the closest rural stationsEstimate of actual UHI by referencing the closest rural stations – again categorized by population density

And the relevant table:

Temperature delta from nearby rural areas vs population density

Temperature delta from nearby rural areas vs population density


Here’s what the author has to say:

On the one hand, it indicates the presence of warming trend over 0.3 °C/decade in Japan, even at non-urban stations. This fact confirms that recent rapid warming at Japanese cities is largely attributable to background temperature rise on the large scale, rather than the development of urban heat islands.

..However, the analysis has also revealed the presence of significant urban anomaly. The anomalous trend for the category 6, with population density over 3000 km−2 or urban surface coverage over 50%, is about 0.1 °C/decade..

..This value may be small in comparison to the background warming trend in the last few decades, but they can have substantial magnitude when compared with the centennial global trend, which is estimated to be 0.74°C/century for 1906–2005 (IPCC, 2007). It therefore requires careful analysis to avoid urban influences in evaluating long-term temperature changes.

So, in this very thorough study, in Japan at least, the temperature rise that has been measured over the last few decades is a solid result. The temperature increase from 1979 – 2006 has been around 0.3°C/decade

However, in the larger cities the actual measurement will be overstated by 25%.

And in a time of lower temperature rise, the UHI may be swamping the real signal.

The degree of urbanization around each site was calculated from grid data of population and land use, because city populations often used as an index of urban size (Oke, 1973; Karl et al., 1988; Fujibe, 1995) might not be representative of the thermal environment of a site located outside the central area of a city.

Case 6: California Counties by population show a distinct UHI signature.

My friend Jim Goodridge, former California State Climatologist identified the statewide UHI signature issues way back in 1996. This graph had a profound effect on me, becuase it was the one that really made an impact on me, switching my views to being skeptical. Yes, I used to be a warmer, but that’s another story.

Goodridge, J.D. (1996) Comments on “Regional Simulations of Greenhouse Warming including Natural Variability” . Bull, Amer. Meteorological Society 77:1588-1599.

Goodrich (1996) showed the importance of urbanization to temperatures in his study of California counties in 1996. He found for counties with a million or more population the warming from 1910 to 1995 was 4F, for counties with 100,000 to 1 million it was 1F and for counties with less than 100,000 there was no change (0.1F).

He’s been quietly toiling away in his retirement on his computer for the last 15 years or so making all sort of data comparisons. One plot which he shared with me in 2003  is a 104 year plot map of California showing station trends after painstakingly hand entering data into an Excel spreadsheet and plotting slopes of the data to produce trend dots.

He used every good continuous piece of data he could get his hands on, no adjusted data like the climate modelers use, only raw from Cooperative Observing Stations, CDF stations, Weather Service Office’s and Municipal stations.

The results are quite interesting. Here it is:


I’ll have more interesting revelations from Jim Goodridge soon.

Case 7: NASA JPL’s climatologist says UHI is an issue

This press release from NASA Jet Propulsion Lab says that most of the increase in temperature has to do with ubanization:

[NASA’s JPL Bill] Patzert says global warming due to increasing greenhouse gases is responsible for some of the overall heating observed in Los Angeles and the rest of California. Most of the increase in heat days and length of heat waves, however, is due to a phenomenon called the “urban heat island effect.”

Heat island-induced heat waves are a growing concern for urban and suburban dwellers worldwide. According to the U.S. Environmental Protection Agency, studies around the world have shown that this effect makes urban areas from 2 to 10 degrees Fahrenheit (1 to 6 degrees Celsius) warmer than their surrounding rural areas.

Patzert says this effect is steadily warming Southern California, though more modestly than some larger urban areas around the world. “Dramatic urbanization has resulted in an extreme makeover for Southern California, with more homes, lawns, shopping centers, traffic, freeways and agriculture, all absorbing and retaining solar radiation, making our megalopolis warmer,” Patzert said.

CASE 8: You can see it from space. NASA (not the GISS division) measures it. Here’s a report they presented at the last AGU meeting in December 2009. Gee, that curve below looks like Reno, NV, doesn’t it?

profile illustration showing the heat island effect of an urban area

The urban heat island effect can raise temperatures within cities as much as 5 C higher than the surrounding countryside. New data suggests that the effect is more or less pronounced depending on the type of landscape — forest or desert — the city replaced. Credit: NASA

› Larger image

thermal images of suburban and urban Atlanta

NASA researchers studying urban landscapes have found that the intensity of the “heat island” created by a city depends on the ecosystem it replaced and on the regional climate. Urban areas developed in arid and semi-arid regions show far less heating compared with the surrounding countryside than cities built amid forested and temperate climates.

“The placement and structure of cities — and what was there before — really does matter,” said Marc Imhoff, biologist and remote sensing specialist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “The amount of the heat differential between the city and the surrounding environment depends on how much of the ground is covered by trees and vegetation. Understanding urban heating will be important for building new cities and retrofitting existing ones.”

Goddard researchers including Imhoff, Lahouari Bounoua, Ping Zhang, and Robert Wolfe presented their findings on Dec. 16 in San Francisco at the Fall Meeting of the American Geophysical Union.

Satellite imagery of suburban (top) and urban Atlanta shows the differences in daytime heating, as caused by the urban heat island effect. Credit: NASA Goddard’s Scientific Visualization Studio

› Larger image (suburban)

› Larger image (urban)

Yep, UHI is alive and well. Anybody with an automobile dashboard thermometer who drives a commute from country to city can easily measure UHI, and you don’t have to be a climate scientist to prove it to yourself.

UPDATE: For a primer on how UHI is not dealt with by NOAA and CRU, have a look at this Climate Audit post:

Realclimate and Disinformation on UHI


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Henry chance

Menne study is More Gooder because I remember they cherry picked 43% of the data while Mr Watts was dithering and had only evaluated 87% of the stations.
Honestly Menne was a little obvious in trying to prematurely pull the trigger and knock down a study before it was complete. A Pre emptive strike.

Given this data, and given that warming per capita falls off with increasing population density, I think its a fair conclusion that the suburbanization/sprawl trends of the late 20th century are generally to blame.

Jeff L

I wish I could record my car thermometer driving into work / driving home. I live in a rural area outside Denver & work in downtown Denver (Colorado, USA, for non-US readers). I almost always see temps 5-10 deg warmer inside the UHI at the office than at home.
UHI existence is a complete non-brainer for anyone who has had a chance to observe the transition (especially at night, when mixing is less pronounced) . It’s simple physics – all that concrete, asphalt, bricks, etc absorbs more heat than vegetated rural surfaces & re-radiates it, thus increasing the temperature.
What an inconvenient fact!
REPLY: Get one of these, get one of those cheap window mounts for flags that stick above the roof line a foot or so, attach it with a couple of nylon zip ties and drive happy:
Then download the data, and use the included software to plot it. So easy a caveman could do it. I’ll be happy to feature anyone’s UHI plots here. – Anthony

steven livingston

I’m not even sure what this is controversial. I’ve felt this effect many time while driving at night while exiting big metropolitan centers…. with the window down an inch during october or in march/april….. as soon as the corn stalks start appearing you’ve gotta turn on the heat or roll up the window. It’s one reason so many raccoons are roadkill… they’re attracted to the warm asphalt…. the heat is released slowly over the night but they love it just the same…. and there’s a lot of asphalt in the city.

4 billion

If UHI is influential, why does land based temperature data show close agreement with Satellite data?

Kevin Kilty

The week after New Year, when Cheyenne was quite cold, I drove the city east-west then north-south, and finally all around the belt loop. Outside the city the temperature ranged from -3 to the east to -4 north, to -6 southwest and -2 to the south. Within the city proper temperatures varied from -1 to +1. No, no UHI here. The effect needs a study involving real measurements and not just a statistical regression of “matched” city pairs, or worse, a regression of two big sets homogenized ahead of time.

re: Case 4 BoM blames the Melbourne record high minimum UHI.
In an O/T comment on the previous WUWT post along with this story I mentioned another story out of BoM (link below). I dont really know who is who in BoM, CSIRO etc, but would love to know the politics right now.
Here William Kininmonth (former Deputy Head of the Bureau of Meteorology and head of that body’s Climate Centre) highlights distortion of temp data:


You only have to look at the night sky with a infra red “heat” camera to see the “bubble” of heat radiating from towns in the distance, you cant refute hard evidence like this with stupid statistics or models, I have seen it with my own eyes on a clear night as will have any amercian abrams tank commander driving around in Iraq who uses the technology to see bodies hiding in the dark. Check out some of the abrams infrared night sight tank footage and you can see it yourself!

Tim McHenry

I thought that at least some datasets were corrected routinely for UHI. Is that the case, and are they still correcting the data? How have they determined the extent to which they should adjust the data? These questions are very important because the problem is such an obvious one. Do people not listen to their local weather girl when she says, “Low of 20 tonight, but OUTLYING areas may get to 15”? This is just common sense to any of us living outside the city.

Paul Wescott

There are heat bubbles even in rural communities. Best example can be found in the Hinkel et al. study of Barrow, AK. Barrow doubled in size over the satellite era, so I expect its heat bubble grew along with it. Given the GISS method of establishing trends in the Arctic, Barrow may have contributed significantly to the supposed remarkable warming of the Arctic.

Kevin Kilty

It isn’t just bricks and asphalt. Cities are situated differently than rural surroundings — sometimes a bit lower in elevation and along a stream or river. In the plains they have more trees–in forests they have fewer. The buildings provide a different view of the sky — hide it at night, and provide canyons with lots of surface area to absorb sunlight in the day. One important issue is the effect of heat dissipation from HVAC, industry, lighting, and so forth. The heat dissipation alone ought to amount to a watt per square meter, which is the order of the “greenhouse effect.” A lot of this dissipated heat has diffused deeply into the earth under cities. And time dependence is what is most important. It is a complicated matter whatever the pundits may say.

Fred from Canuckistan

Never worry about desmogblog . . . its a fools paradise front operation for David “Dr. Fruit Fly” Suzuki’s global warming hysteria organization. All fear mongering AGW hysteria hyping crap all the time.
The dude that runs is a PR flak that makes his living shilling for the local socialist/progressive party.
Always good for a few laughs round these parts.

David L. Hagen

Off Topic
Sun 10 PM EST PBS.org TV showing Masters of the Arctic Ice
highlighting impact of climate change on the Arctic.
By National Geographic
Claims climate change is clearly shown in the Arctic.

Rod Smith

Would it be possible to accurately “correct” surface temperature readings using infra-red satellite pictures? Even if not totally accurate, would it likely be a better technique than the “corrections” that are currently used?
How accurately can a surface temperature can be determined using such a source? Could such pictures be an even better way to collect surface temperatures than now used?
Assuming NOAA knows exactly where the climate sites are – which is doubtful – such pictures might be useful as a management tool to detect changes in siting or surroundings causing higher readings.


Off topic
Now that Susan Solomon NASA has conceded negative feedback re water vapour
does this mean all projections have to be reworked?


In the second graph you compare Tokyo with Hachijo Island. A nearby island, called Miyake Island being 180 km from Tokyo, exhibits almost no increase in temp at least for 1940-present, though the year-to-year oscillation pattern is the same as Tokyo.

Theo Goodwin

Your work is excellent. Thank you. No doubt, it was undertaken in the spirit of Orwell who said that in these times rational men have a duty to state the obvious.
I cannot imagine someone actually denying the urban heat island effect. To prove it to yourself, all you have to do is drive from the city to the suburbs or vice-versa. Maybe people get confused among city, suburb, and exurb. To see the effect, you have to visit the city, that part of the metropolitan area that has all the older brick buildings that are jammed together. Driving from the suburbs, with their spacious lawns, to the exurbs, with their huge lawns and McMansions will not do the trick.


the chinese are getting it:
1 Feb: China Daily: Equal plan of emissions rights
By Chen Longxiang
The most crucial task for China in international climate talks is to seek an equal arrangement of emission rights that could guarantee its development interests and basic human rights, says Ding Zhongli, a renowned geologist and vice-president of the Chinese Academy of Sciences in an interview with China Daily.
While in allocating emissions rights – or the quota of emissions – for different countries, the reduction proposals of the IPCC (United Nations’ Intergovernmental Panel on Climate Change), the G8 and the OECD (Organization of Economic Cooperation and Development) did not consider that the cumulative emissions per capita of developed countries throughout modern history (from 1900 to 2005) has been 7.54 times that of developing countries.
They assigned developed countries 2.3-6.7 times the future emissions quota per capita more than developing countries, which would remarkably deprive the development and interests of poor countries…
In his paper on the major proposals for carbon emissions reduction and some related issues, published on February issue of “Science in China”, Ding analyzed the trap hidden in the dialogue on emissions reduction.
The “trap” consists of: First, demonstrating the high sensitivity of global temperatures to atmospheric CO2 concentration; second, emphasizing the catastrophic impacts of global warming on the biosphere and on humans; third, making the value judgment that the extent of temperature increases since the Industrial Revolution should be controlled under 2 C within this century; fourth, calculating that the atmospheric CO2 equivalent concentration should not exceed 450 parts per million by volume within the 2 C model; fifth, defining the responsibilities of developing countries in terms of long-term emissions reductions; sixth, fixing the quota of developing countries in long-term emissions reduction.
The key point here is that once the concentration target of 450 ppmv is established, the permitted emissions from fossil fuel combustion and cement production from 2006 to 2050 are fixed accordingly.
Even though the ocean and land continue to absorb 45 percent of carbon emissions, the total amount of emissions that people all over the world could discharge is at about 255.11 GtC. In the total amount of emissions, however, after developed countries determine their proportion of how much they should reduce, there is not much vacancy left for developing countries to exercise emissions freedom.
Developing countries may not be fully aware of the “trap”. …

This is a no-brainer. I live in the country ten miles from a small city of 25,000. It is perceptively warmer most of the time in town than it is out in the country. Even my wife comments on it and she has no interest in climate change at all other than politely listen to me on the rare occasions that I bring it up.
Siting of the weather stations used for climate change predictions in urban areas and then inadequately compensating for the heat island impact is little more than scientific fraud.

Ian W

Any change in land usage will alter the temperature profile. So irrigating arid land will increase humidity and prevent low minima moving the average temperature higher. Growing trees may result in daytime transpiration of considerable volumes of water in hundreds of litres a day per tree leading to cooler temperature maxima.
Shouldn’t planetary energy content be measured rather than transient heat in the atmosphere as it is on its way out to space?

Bob Buchanan

OK …. so urban areas, which are created by people, are getting warmer. If we average the UHI temps with the non-UHI temps we are warmer than if we had no urban areas. We really do have anthropogenic global warming; just not caused by greenhouse gases.


Thanks for including my blog post on the UHI in Japan! It’s great to see the work get a wider audience.
Can I get a “most favored nation status” – a listing on your blogroll?
REPLY: sure -A

Kevin Kilty

Anthony Watts – It was early evening and CYS, which is about halfway down the longest runway at the municipal airport to the east of the terminal, was reporting -1 as I left my home to start this trek and -3 by the time I returned just over an hour and a half later. I have no measurement of the offset between my thermocouple and the airport station, unfortunately. There is a lot of open runway and taxi-ways at the airport, which the military uses as much as anyone, but it is within the city. As I drove by the west end of the runways (about a mile to the west of CYS) I measured 0. When I got home both CYS and I were reading -3, but I am downwind on this evening from every source of heat.
Wind was out of the west-southwest and quite light as shown by steam clouds rising from the refinery southeast of town, and the Dyno-Nobel plant southwest of the city. The coldest place (-6), to the southwest is a low area along a local creek, and the warmest boundary region to the south of town is high ground along US 85 known locally as the Denver Hill. Interestingly the warmest region within the city was a low area on the north side of the city where US 85 intersects a drainage known as Dry Creek. It was +1 in here. The coldest place in the city proper was -4 in the southwest part of the city along US 30.
I can probably find the NWS archive for the evening in question.
REPLY: No need, just wanted to make sure you weren’t driving in 20mph winds. Mixing near the boundary layer negates the effect. -Anthony


“Urban Heat Island Myth is Dead“.
They should talk to James Hansen. He knows it’s alive and well. He uses it in his product.


“Urban Heat Island Myth is Dead“
Huh, then what’s this?:

Joel Shore

If you read beyond the headline of the Desmogblog, you would see that “Urban Heat Island Myth is Dead“ was shorthand for the point that the urban heat island effects are not having a significant impact on the global temperature data sets that we are using to look at global warming.
It was not a claim that urban heat islands do not exist.
REPLY: Oh I understand, but you don’t get to read my email. Many Huffponians were convinced by the title alone. At least my title is accurate, and that the purpose is to show (for those folks that can’t read past the title) that UHI remains an issue.
But then again, you gripe about most everything here. So I’m not surprised you’d gripe about this too. Oh, you might want to read this from McIntyre, as your scifi hereos don’t seem to correct for it:
– A

Robert Wykoff

I spend a lot of time wandering the northern nevada deserts day and night. Temperatures are always warmer, summer and winter at night in the city than out in the boondocks (even when the boondocks are significantly lower in elevation. Driving at night is always interesting,especially on windless nights. Temperatures vary extensively based on topography (rocky areas are always warmer). On still nights when you drop into low spots, it can get bone chilling, but when you rise in elevation out of the cold sinking air pool, its suddenly warm and pleasant…these transitions are always seemingly instantaneous. Near creaks and rivers, its always very noticeably colder. Topography, and geology have massive impacts. Transition zones between warm and cold are short, and in most cases utterly predictable if you know and watch the land. Mr watts would have a field day doing a night drive in my cruiser with his thermometers. The surface of one small valley can range in temperature by 20 degrees simultaneously, but we are supposed to believe they can calculate temperatures from 1200 miles away from somewhere with an altitude difference of over a mile.

John Whitman

In the CASE 5: Heatzilla stomps Tokyo, the Japan author partly summarizes – ” On the one hand, it indicates the presence of warming trend over 0.3 °C/decade in Japan, even at non-urban stations. This fact confirms that recent rapid warming at Japanese cities is largely attributable to background temperature rise on the large scale, rather than the development of urban heat islands. ”
This appears to me to be consistent with Anthony’s statement in the CASE 5 – ” And the IPCC (2007) summarized the northern hemisphere land-based temperature measurements from 1979- 2005 as 0.3°C per decade. ”
So, I haven’t done homework about whether other independent (of IPCC AR4 )papers on northern hemisphere land masses show this consistency with the AR4. Sorry.
BUT, has anyone here done homework about if the AR4 statement is consistent with other land masses, like it is with Japan?


I’m a first time contributor (FTC), long time reader (LTR).
The R=0.455 value is not that good of a correlation. Were the temperature stations placed directly in the middle of the city and in which direction did temperature get measured from the city? Was it measured out over the ocean or in towards a desert? What I’m saying is that I highly doubt there is a convenient circular arrangement of stations around the “UHI” of interest to give a symmetrical arrangent of temperatures radiating farther out from the original station(s) within the city. What you could be measuring is the variance between multiple stations because of location such as latitude and altitude (more importantly) rather than the temperatures of what the city raises the avg temperature. This is not to eliminate the UHI effect but to suggest other experimental and procedural (as well as bias) errors are effecting the claim of where all attributable temperature increase comes from. A map of where the stations had their data collected from would be entirely relevant especially along with their altitude.
Just an extra piece of skeptical reading from me is that the pressure systems could be altered significantly from many events such as the UHI or if there was localized melting of glacial patterns etc. Given this possibility where high or low temperatures may become altered relatively altering the flow from what used to be a high pressure system of air into a cooler one, where the flow of air is coming from each station could describe (depending on the location of the measuring station obviously) either an increase in the UHI temperatures or a decrease. So if you were to take for instance the night data as opposed to the day data you could find if there was a significant change in the mixing from wind factors and judge whether there exists a deviation of the temperatures but you could also check for a history of the high and low pressure systems of the areas and if they are altered in any significant way (per statistical analysis which i know you like to do).

Doug in Seattle

4 billion (18:52:46) :
“If UHI is influential, why does land based temperature data show close agreement with Satellite data?”

With 70% of the earth’s surface covered by water what is the likelihood they would differ beyond the amount they DO differ?

Kevin Kilty

Anthony — When I said no UHI here I was joking. It was pretty obvious on this evening (7 Jan), the entire city except for low areas along US 30 at the city’s west edge, was at least 1F warmer than countryside.
REPLY: Well if you want to do it for real with a datalogger, let me know and I’ll send you one. Might make an interesting student lab study. – Anthony

Doug in Seattle

I agree with Mervin that R=.455 is pretty sketchy for drawing any substantial conclusions. The plot doesn’t look to be much more than a cloud of points.
I think the study needs to fine tuned a bit.

Recent California climate variability: spatial and temporal patterns in temperature trends (CLIMATE RESEARCH, February 2007)
Steve LaDochy, Richard Medina, and William Patzert
“If we assume that global warming affects all regions of the state, then the small increases seen in rural stations can be an estimate of this general warming pattern over land. Larger increases must then be due to local or regional surface changes. Using climatic division data, the fastest rates of warming were recorded in the southern California divisions, where urbanization has been greatest. The least warming occurred in the Central Valley, with the more irrigated south (San Joaquin drainage) having greater warming than the less irrigated north (Sacramento drainage). The NE Interior Basins division had cooling over the period of record, although most stations in the northern divisions had insignificant rates of change.”
“The largest temperature increases were seen in the state’s urban areas, led by Southern California and the San Francisco Bay area. . .”
If the excess warming occured only in urban areas, I think we can conslude that UHI exists.

Jason Bair

The temp drops at least 5 degrees between Palmdale/Lancaster, CA and Rosamond…. Every morning on my drive to work


A few years ago I attended a seminar for wx spotters. Those attending were ham radio people. The meteorologist giving part of the presentation said that it was believed that the reason that the city of Chicago had never been struck by a tornado was the city generated so much heat and the heat prevented it.

For Marvin, I’m not much of a statistician I’m afraid. The significance levels are derived from how reliable the fit is – and they are mostly 99%, with a few at 95%.
There is a lot of data with a lot of scatter – but still a significant trend. Confidence in the trend increases with number of points sampled (which is a lot).
The high level of scatter is one of the most interesting points about the paper. Looking at just a few stations might easily send you off in the wrong direction. Micro-climate effects are very influential and maybe impossible to predict in advance.
The other significant point about the paper was the verification of high “real” surface temperature warming over Japan for the period of the study.
I didn’t understand your question “which direction did temperature get measured from the city?” These are stations measuring the temperature at specific locations throughout Japan. The researcher explored the temperatures recorded to the population density at that point (not in the center of the city).
CO2: An insignificant trace gas?

Peter G

The main RSS feed seems to have died.

David Ball

Hey there Joel Shore, I remember you telling me you had nothing to do with Desmogblog when I asked you about the lies they posted about my father. What do you have to say about that now? Your credibility is in question.


You don’t have to be a scientist to notice that it’s hotter in the middle of any town/city with bitumen streets, buildings and no trees, than it is in the surrounding countryside with trees, grass and only the occasional building. They must drive around in air conditioned cars and work in air conditioned offices to make statements such as that. UHI is alive and well !


An article said that in Israel (I think that’s right) home owners are required to white-wash their roofs every year. Seems they realize UHI is very real and move to minimize it.

Warwick Hughes

Good post Anthony, UHI is alive and well at Canberra Airport too – 0.3 degrees C per decade, and has been fed for years into global trends. See my post on 12 Jan 2010


I can say the Japanese study by Fujibe (Case Study) is an utter bogus, because the years since 1979 constitues the very period where dramatical urbanization took place all over Japan.
Until 1960s where the Olympiad was held in Tokyo (1964), mostl parts of Japan were rural and cars were rarely seen in the countryside. At a number of stations keeping a long observation record, the temperatures exhibit no clear trend whatsoever from the 1880s up to 1960-70s, but show a remarkable rise thereafter, 1 to 2 degC for middle-sized cities and 0.5 to 1 degC even for small cities/towns.


I ment Case Study 5. Sorry.


This is a 1980 analysis of NZ weather stations showing the effect of UHI and particularly shelter, and the way these have interacted to increase temps by about 1C.
Note it was produced to counter the allegations of then young guns Salinger and Trenberth, now famous in the Climategate emails.

Dave N

Case 7’s link to the JPL climate site seems to have been removed, or redirected?
Thanks for the link to the temp/humidity data logger. I’ll be looking into one.
REPLY: The link was orphaned and then redirected to the main page by NASA’s new climate website for some reason, alternate found, fixed. – Anthony

David Ball

Sal (20:55:34) : Correct Sal, but more importantly, it is affecting the averaging, especially when certain stations are used (urban) and others tossed out (rural). Their claim of “nothing to see here” is ignorant. I will decide for myself if there is nothing to the effect of UHI. I guess it is hard for me to fathom that there are people out there who would just accept their claim of irrelevance.

Anthony, Long ago when we were discussing the Parker paper I was begging everyone to take a look at the BUBBLE study. Have a look. a very detailed look at the problem
There is also a website somewhere.. arrg