This is a small bombshell. I’ve been telling readers about UHI since this blog started. One notable example that I demonstrated by actual measurement is Reno, NV:
Click for larger image
The IPCC reports have minimized the effects of UHI on climate for quite some time.
From Warwick Hughes:
The IPCC drew that conclusion from the Jones et al 1990 Letter to Nature which examined temperature data from regions in Eastern Australia, Western USSR and Eastern China, to conclude that “In none of the three regions studied is there any indication of significant urban influence..” That has led to the IPCC claim that for decades, urban warming is less than 0.05 per century.
A paper in JGR that slipped by last fall without much notice (but know now thanks to Warwick Hughes) is one from Phil Jones, the director of the Hadley Climate Center in the UK. The pager 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. And even more notable is that Jones result are directly at odds with another researcher at Hadley, Dr. David Parker.
It seems that Parker is looking more and more foolish with his attempts to make UHI “disappear” To back that up, the National Weather Service includes the UHI factor in one of it’s training course ( NOAA Professional Competency Unit 6 ) using Reno, NV.
In the PUC6 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
What is striking about this is that here we have NOAA documenting the effects of an “urban heat bubble” something that Parker 2003 et al say “doesn’t exist“, plus we have inclusion a 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, and Hadley’s Dr. Jones admits it is real and quantifies it, I’m comfortable in saying that Parker’s claims of UHI being negligible are pure rubbish.
Its all about location, location, location. And climate monitoring stations that are poorly sited and that have been overrun by urban growth clearly don’t give a pure signal for assesment of long term climate trends. This puts a real kink in the validity of the surface temperature data in GISS and HadCRUT and could go a long way towards explaining the divergence between satellite and surface temperatures in recent years.
Adam (10:36:30) :
So, where does the warming trend come from in the satellite data??
Dr John Christy cites in this debate that satellite data is contaminated by UHI. Listen to the part when he talks about Sierra Nevada. The satellite data for the towns in the valley show warming whereas in the mountains and troposphere there is next to nothing.
http://jlf.streamhammer.com/speakers/globalwarmingdebate021109.mp4
Check out SurfaceStations.org for information on station siting. I believe Anthony is working on a study along those lines, but doesn’t have all the data in yet.
In answer to your question — Yes, stop using that data to show climate change. It may be valid to use to gauge changes in the local, microclimate, but when you include that site in the global dataset, it contaminates the data and shows more warming than actually happened.
The ‘average surface temperature’ or ‘average temperature anomaly’ are estimates. The raw data is manipulated, averaged, weighted and adjusted 8 ways to Sunday to reach those numbers. Bad data caused by UHI causes artificially high estimates.
Some of the more cynical ones of us think GISS uses surface stations for their data for this very reason, but that’s a story for a different time.
Hansen is stirring up more trouble along with the Guardian
http://www.guardian.co.uk/science/2009/mar/18/nasa-climate-change-james-hansen
How dare he say that the democratic process is being undermined when nearly all dissenting scientists are being told to shut up or insulted?
How dare he say that the democratic process is being undermined when the taxpayer has not had a say on whether they want to pay behaviour change taxes?
How dare he say that the democratic process is being undermined when electorate clearly don’t vote for the Green’s hysterical issues?
How dare he say that the democratic process is being undermined when he has the majority of politicians kissing up to global warming and the taxes it could bring government?
How dare he say that the democratic process is being undermined when the public clearly do not believe in global warming hysteria?
How dare he say that the democratic process is being undermined when he has been manipulating science that is funded by the taxpayer?
How dare he say that the democratic process is being undermined when the Greens have shown they have no respect for the democratic process every time they use physical and verbal attacks against industry?
How dare he say that the democratic process is being undermined by corporate lobbying when corporations donate vast sums of money to environmental groups and science?
Posted this at real climate just to see if I got a response.
Rob Says:
18 March 2009 at 12:22 PM
Does CO2 drive temperature rise or is it just UHI, according to the Jones et al study of 2008 40% of the increase in global temperature from 1951 to 2004 is from the Urban heat island effect.
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.
http://www.agu.org/pubs/crossref/2008/2008JD009916.shtml
[Response: Read the paper a little more carefully. Jones et al suggest an urban effect in china (not globally) that reduces the regional trend (1950-2004) from ~1.3 deg C to 0.8 deg C. Still plenty of non-urban warming. Note too that this is with respect to nearby ocean temperatures which is not ideal. – gavin]
The Royal Meteorological Society of the UK is running an experiment for schools on the subject of UHI.
Interesting project and along the lines I was thinking but not enough control over the precision (garden thermometers) with no effort to calibrate to even the low tech water ice solution leaves a considerable margin of error in the measurements, although the data is good as a point of reference on how to set up a more controlled sample.
http://www.metlink.org/urban/index.php
http://www.metlink.org/images/urban/uhi-manchester.gif
Larry
Isnt the UHI a transient effect?
One day open field, 1 year later surrounded by houses. 10 years later surrounded by houses. 11 years later surrounded by more houses. etc.
In this scenario there should be 2 step increases in temp. There is unlikely to be a steady rise as most show!
Bill
For those of you wanting to rush out and study UHI effects. Settle down! This has been done for years. Pick up a copy of any 100 level college text for Physical Geography and look in the index. One on my shelf references the following: T.R.Oke, 1978, Boundary Layer Climates, Methuen & Co. p.254. Note the date. This is not a new idea. We’ve been teaching it for years to first year college students.
Aron (11:38:16) :
“Dr John Christy cites in this debate that satellite data is contaminated by UHI. Listen to the part when he talks about Sierra Nevada. The satellite data for the towns in the valley show warming whereas in the mountains and troposphere there is next to nothing.”
Sorry, John Christy has already answered this question directly on a previous blog post:
http://wattsupwiththat.com/2008/03/08/putting-a-myth-about-uah-and-rss-satellite-data-to-rest/
——————————————–
Anthony inquired:
“I’ve had some queries on my blog recently that are suggesting that the UAH and RSS satellite data is somehow “tuned” to the surface data, or that the surface data is used to provide some offset function. Given that the MSU looks at microwave emissions from oxygen, essentially a first principles measurement, I don’t see any reason that surface data would be used in any way to adjust the MSU data.
But I figured I’d ask the source, if you’d care to elaborate. If not, no worries.”
To which Dr. Christy graciously responded within a couple of hours:
“No other data are used in the construction. That is why we can do comparison studies without any interdependence.”
——————————————————–
I didn’t get to watch your video link, but, based on John Christy’s response above, I wouldn’t be surprised if you took him out of context.
[1] IPCC assumes that UHI is < 0.05C per century, and can therefore be discarded as noise.
[2] Jones (who is the previous authority relied upon by the IPCC) finds a UHI of approx 0.1C per decade, in China from 53 Years of data.
[3] For the same time frame (53 yrs) he finds “real” warming of 0.81C.
This suggests that he found
[4] A total warming signal of 0.81(AGW) + 0.5(UHI) = 1.31C over a 50 Year period.
So he gets to have his cake (AGW) and eat it too (refer to the data).
It’s possible that Jones is intellectually backing away from AGW.
The bottom line however is that the IPCC are out by a factor of 20.
Real Climates response (Ref Rob (11:54:43) : above) just puts the emphasis on the AGW signal and ignores the UHI elephant that has entered the room. It also gives no reason why the results for Urban China are not applicable anywhere else.
Is there something fundamentally different in Chinese cities – I think not.
Aaron, the green tranzies, Greenpeace, WWF and Sierra Club, amongst others, force their aggenda upon democratically elected governments in through coercion and vandalism.
“Millenarianism (also millenarism) is the belief by a religious, social, or political group or movement in a coming major transformation of society after which all things will be changed in a positive (or sometimes negative or ambiguous) direction.”
http://en.wikipedia.org/wiki/Millenarianism
Of the same kind of “cargo cults”, with the difference that the cargo now is a carbon cargo vessel.
Someone asked me the other day what “sceptics” would start talking about now that La Nina and solar minimum had passed and global warming ceased to be hidded by these two short term factors.
My response – they would start to attack the “data”.
If nothing else you are predictable. Those who think this is a bombshell have not bothered to read the literature and failed geography (noting the planet is 70% water).
In Gavin’s reply to Rob’s post on RC, he replies to say the study was in China and not a global one. Of course this is correct, but last time I checked China was still part of the globe, and despite their communist system, physical processes work there exactly the same as they do everywhere else.
from the abstract:
“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.”
Do they have a plot for “the influences of the cities on surface temperatures” ?
(I do not want to buy the article). Or is it an assumption?
I think that a lot more gas oil and coal have been burning ( viz the CO2 curve) since WWII than before. With increasing affluence in the west came increasing number of cars and carelessness in heating economies, imo.
What I have never understood about the London “no increased UHI over this period” is that London had many more “man made” autumn, winter, spring, fog days in the early part of the 20th Century than it does now (almost none), so how did Jones adjust for this?
Intuitively, I would have thought that fog days makes the climate appear much colder by depressing the daytime temperatures.
“DJ (12:38:08) :
Someone asked me the other day what “sceptics” would start talking about now that La Nina and solar minimum had passed and global warming ceased to be hidded by these two short term factors.
My response – they would start to attack the “data”.
If nothing else you are predictable. Those who think this is a bombshell have not bothered to read the literature and failed geography (noting the planet is 70% water).”
someone obviously failed spelling……
Did you see “The prophecy”?…We all know that the guy is a grown up by now..
Guess what his name is?
I have a question for Dr. Christy. Do the satellites have sufficient resolution to demonstrate UHI if the correct procedures were implemented?
Could this latest paper from Phil Jones be an attempt to distance himself from an alleged use of fraudulent data in a previous paper which “demonstrated” that UHI was “insignificant”?
See http://www.informath.org/apprise/a5620.htm
If cities exhibit the UHI effect and they surely do then as this heat rises from the cities it will have some effect on the atmosphere above the city. Does anyone know of any studies as to what altitude this effect would be measurable and to what effect this would have on the satallite measurements?
If UHI is real (which everyone agrees it is) and satellites are reading actual temperature (which I believe to be the case), then at lower altitudes (“near surface layer” http://discover.itsc.uah.edu/amsutemps/amsutemps.html ) uncorrected satellite data has to include UHI effects. Since (I assume) UHI represents a smaller percentage of satellite data (RSS and UAH) relative to land based data (GISS and HadCRUT), the satellite data should give a more accurate (but not uncontaminated) global temperature.
Two Questions:
1 – Is satellite data corrected for UHI, if so how?
2 – How high does the UHI effect extend?
“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
I’ve come late to this discussion and others have commented before but the above statement by Jones must be rubbish. To claim that London and Vienna in 1900 are comparable with London and Vienna in 2000 is absurd. There is no way their UHI effect can not have grown!
Now we know. When your mom screamed “Fer Crissakes close the door! Do you want to heat the whole outdoors?” She was right.
Aron (11:38:16) :
“Dr John Christy cites in this debate that satellite data is contaminated by UHI. Listen to the part when he talks about Sierra Nevada. The satellite data for the towns in the valley show warming whereas in the mountains and troposphere there is next to nothing.”
is this what you mean ?
as warm air goes up, it should also increase satellite temperatures in the lower troposphere.
as satellite data is not corrected for this effect, satellite temperatures are to high and their uptrend is also too steep.
Corrected ground based data should be lower than uncorrected satellite data. as ground based data is not lower, their uhi correction is too small.
as uhi correction is too small in ground based data, increasing uhi results in a too steep uptrend.