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.
That’s just it, Stephen. All of the “science” involved in proving and/or disproving man’s influence on climate is clearly NOT settled. There are so many variables and unknowns that it is ignorant at best to state AGW is real. At worst, it is a blatant attempt to control population and wealth through lies and propaganda.
Personally, I don’t believe CO2 is doing anything to the overall temperature trend of the earth. I don’t even know if it’s possible to determine with any accuracy what that trend is or should be. Even if we could determine that, I don’t think there is any way to accurately measure it. For example, do we just continue what is done today – (high temp. + low temp)/2? Should we take hourly readings and divide that sum by 24? Should we measure temperature to the hundredth of a degree? Thousandth?
I think the UHI effect was intuitively obvious — just didn’t know how much of an effect. Its probably a larger impact than indicated in the report — since its a Hadley report, and its intuitively obvious they will minimize the effect (if for no other reason than peer pressure).
None the less, I applaud Phil Jones and Hadley for the report.
Remember too that Shanghai suffers from dense smog. When that clears up the city will receive more sunlight and heat up. That from reducing air pollution!
Yep. Kudo’s to Phil Jones for admitting the obvious.
I live in a part of rural Britain, south-west England to be accurate. At the risk of some repetition, during the winter when I used to have to pick up my son or daughter 8 miles away in the provincial city, my car’s air-con system would read something like -0.3C, flashing the ice warning. After a couple of miles, allowing for wind friction over the sensor, the temp reading would read something like -0.1C, still flashing the ice warning. By the time I’d reached the outskirts of the city the temp reading is up to 1.0C, & in the city centre it would read 2C! So the heat island effect is real. Everyone I know seems to remark on the same thing during any winter, mild of otherwise, it’s warmer in the city than in the countryside. Whether this “real” effect is truly accounted or “adjusted” for is unknown.
Is there still some enthusiasm to check the UK weather stations on the cards? I would certainly help on the south-west stations. As said before we may encounter restrictons as we’d be accused of spying for terrosist organisations or something ridiculous, but we could have a go! Does anyone know if the CET station system accessible to the public?
Perhaps we should look at UHI effect as local weather rather than indication of climate change. I also think we need to distinguish between real temperature increases and measured temperature increases due to UHI effect.
As Anthony has shown, the supposed increases are most likely caused by bad measurments due to siting issues rather than real temperature increases of the climate.
I have two questions that have been bugging me for some time. Firstly, is there any accessible info on what proportion of global air temperature recording stations are in urban/airfield locations as against open (not forested) rural locations? Secondly, given that the UHI effect can be so strong, has anyone in, say, Europe or North America constructed and compared temperature trends for these two different environments over the past 50 years or so (and making allowances for land elevation effects)?
Lemme see if I can guess RC’s response.
“It doesn’t matter…”
This is not true. Satellite measurements are adjusted and calibrated using surface temp records. So UHI also contaminates satellite data. It would be nice if this were as simple as Al Gore and Gavin Schmidt say.
If we are on a long term cooling trend, due to orbital factors, which is likely due to the fact that our current interglacial is somewhat long in the tooth, then it means nothing with regards to those issues.
I don’t know if anyone has mentioned this before but there is a study of UHI in the UK currently underway. Reading, Manchester, Belfast, Birmingham, Cardiff, Exeter, Glasgow, Oxford, Sheffield and more cities are due to be surveyed under a Royal Meteorological Society experiment. There’s a very nice picture of Manchester’s UHI.
http://www.metlink.org/urban/background.php
I’m not entirely sure what they intend to do with the information but the goals of the hosting organisation seem very compatible with the intentions of the good people here a WUWT and Surfacestations.org
More specifically, the meteorological aims of the project are to:
. improve individuals’ abilities to collect and record weather data;
. appreciate weather differences from region to region;
. understand the reasons for the differences.
The long-term benefits of MetLinkInternational are seen as:
. a wider interest in the teaching of meteorological topics at both primary and secondary levels;
. a greater awareness of, and enthusiasm for, meteorology as a science-based subject;
. the recognition of meteorology as one of the few fields of study that can embrace the full scope of experimental method, scientific analysis and interactive ICT skills in an engaging way;
. the acquisition of a meteorological information and data resource which will be of value long after the project has ended.
Can someone explain to me how surface station readings impact satellite readings (in laymans terms)? I’m curious to understand it better.
I assume that the past 10 years or so, the impact would be smaller? the UAH readings have been higher this year than last – I assume UHI issues wouldn’t impact that?
Thanks for any info.
Ditto to what Jim, Allen63 and others have been pointing out. Am I missing something? Isn’t this all just common sense? Our local weather broadcasters routinely say things like, “Low of 40 in the city, you may get to mid-30’s in outlying areas.” Anyone with an eye, half a brain, and a temp-gauge can tell that it gets colder outside the city. Combine that with the expansion of the cities around the temp stations over time and you have a factor that simply MUST be taken into account for any accuracy in the record!
TJA @10:10:47
This is not true. Satellite measurements are adjusted and calibrated using surface temp records
Can anyone tell me or show me how?
Robert Wood (09:01:09) :
Satellite data.
I don’t think they heard you. RW has a point, folks. What about the trend in the satellite record?
I disagree with the notion that areas that are already built up won’t show an increase in warming over time. In other words, the statement:
“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.”
Is an assumption, not an observation. Look at London in the early 20th century. What did the roofs of the buildings look like and what material was used on them? What did the road surfaces look like? I would be willing to bet that there was more concrete and cobblestone where there is asphalt “black top” today.
One must not only consider the density of development but also the impact of materials used as they change over time. For example, it has been estimated that the use of “cool roofs” and “cool pavements” could reduce the Los Angeles heat island by 1 to 2 degrees in summer. Were the roofing and paving materials in use in 1900 “cooler” than the materials being used in 1999? How has the albedo changed? What was the impact of smokestack output on solar heating of these surfaces in the early 20th century and with clearer urban skies today, are we seeing more solar heating of these surfaces resulting in more heating?
To simply state that the urban heat island signature is doesn’t change of the course of the century ignores changes that have taken place over that century that can greatly impact the UHI signature. No evidence is given to support the notion that there is no change over time in London or Vienna. It is simply an assumption pulled out of thin air.
TJA (10:10:47) :
“Satellite measurements are adjusted and calibrated using surface temp records. So UHI also contaminates satellite data.”
No. I believe that it has even been discussed on this blog before that satellite measurements are NOT calibrated using surface temp records. Although, what is interesting, is that satellite (RSS and UAH) anomalies are highly correlated to those from GISS and HADRUC…
http://tamino.files.wordpress.com/2008/03/4way.jpg
So, where does the warming trend come from in the satellite data??
This is somewhat OT – but funny and related to the movement toward acceptance of AGW as myth:
http://newsbusters.org/blogs/p-j-gladnick/2009/03/18/global-warming-alarmist-irked-cold-weather
All I can think of is “Duh”
UHI seems like an obvious concern with urban stations or stations being encroached upon by development, but somehow it is largely dismissed as a “Red Herring” when ever the subject comes up in climate circles.
Maybe the thought is local weather is not climate, but it is when you have enough of it.
Sort of OT, unless you consider all that asphalt that tends to be found in cities. Long time lurker here, but talk of UHI reminded me of a conversation with my 9 year old son yesterday.
One of the first really nice warm sunny days in Ontario so far this Spring. Driving with my boy, who had his window down. He made a comment about how much his black jeans were absorbing the heat of the sun, which felt good compared to the cool air coming in his window as we drove. He was chattering away about how much heat the colour black absorbs compared to lighter colours (totally without my input, BTW). So I asked him “So if black does such a good job absorbing heat, do you think it’s a good idea to put a thermometer close to a road?” His answer: (with the kind of incredulous superiority in his voice that only a kid can deliver) “Duh! Any moron knows that won’t work. The road will make it hotter.” Mr. Parker… nuf said.
I was having the same thought when I saw you had made the above post.
This would be a wonderful science lab project for some interested college students.
I’m not sure how many of you remember the “Day in the life of ” photography projects, where hundreds of photographers tried to document daily life all over a single country on the same day.
Here is the concept I propose.
Working title – One days temperature profile project
Recruit about 30+ interested students to the project in a location.
Build 30 identical low cost Stevenson screen enclosures with identical thermometers which are calibrated to a common reference source like a water ice solution.
Select a relatively compact moderate sized city surrounded by rural areas.
Pre-plan a grid one or more measurement locations for the Stevenson screens that meet good sighting protocols with photo documentation and GPS coordinates.
Train the students how to set up the screens allow them to stabilize (ventilated screens would stabilize quicker), and record pre-planned temperature readings
Have all the students take temperatures at these pre-determined locations at simultaneous fixed time intervals on the same day.
That would allow you to produce a one day snapshot of the thermal profile for the entire grid area at very high resolution.
Repeat the exercise on several random days.
Some enterprising graduate student could write a thesis on this and do the world a major favor in documenting the daily thermal profile of a community at high resolution.
You could even include some “poor location measurement sites” like roof tops, near roadways etc as reference controls to show how badly such locations bias the apparent temperature of the city.
Any meteorology professors or related professions willing to organize such a One Days Temperature Profile project?
Larry
It seems to me that it wouldn’t cost much or take a lot of staffing to do studies of UHI effects, and that there could be a lot of bang for the buck in the results (whichever way they turn out). (Even college or high school kids could do some of them as a project.) This is the “unknown” that could be most quickly resolved. So I hope .1% of that money intended for climate modeling supercomputers gets diverted into this area.
No, at least 10% should be directed to UHI studies, with the bulk of that money going to the Surfacestations Project, the recognized pioneer and leader in such studies.
I did not purchase the article, and so did not read the citations. I can only hope that the work of Watts et al. was cited and credited.
Once again, the Hinkel study of the situation at Barrow, Alaska, is instructive, i.e., a community doesn’t have to be what is commonly thought of as “urban” to experience a significant UHI effect. Because Barrow roughly doubled in size since 1979 (to about 4,700), the increase in cold season average temps with UHI effect looks a lot like Dr. Mann’s hockey stick.
If the other high latitude stations in Alaska, most if not all on airports, are similarly affected, though likely less than fast-growing Barrow, the flat to negative temperature trend at http://climate.gi.alaska.edu/ClimTrends/Change/7708Change.html may in reality be a lot steeper negative.
ISER recently completed a study of economic consequences of climate change in Alaska. I warned them (pre-PDO shift) that examining nothing but positive temperature trends may leave us short of well-thought-out alternative adaptive measures if the climate instead cools. I guess they weren’t being paid to look at that possibility.
Paul
Could this be Phil Jones trying to back-pedal in an effort to put “space” between him and an alleged fraud over a paper demonstrating the lack of UHI effect in China?
See http://www.informath.org/apprise/a5620.htm
ak (07:56:00) saith: “…if a site has always been in a city, the data is still valid for showing the temperature at that location and likewise, the temporal trends. should we stop using data from a site because in 1940 it was in a field and a forest has grown up around it since?”
Great point, ak. The answer is clearly ‘yes,’ especially if it’s a forest of buildings. Yes, UHIs will not affect (*) any current short-term trends. But they’ve already affected the long-term trends (1940 to present) that are used to pretend to show AGW. Something else must now be done to add more fictitious AGW at the same high rate. Something like, say, tampering with the old records. Do we know anyone who would do such a desperate thing?
(*) exception: heavy asphalt coverage will accentuate even short-term urban heating trends. On a very hot day, asphalted areas can jump ~20°F when the rest of the city is only going up ~10°F. Too bad if there’s a sensor there.
And don’t forget, guys. On April 1, everybody move your BBQ another three feet closer to the sensor. (jk)
MattN (10:10:46) sez: “Lemme see if I can guess RC’s response: ‘It doesn’t matter…’”
or “UHI is an outmoded concept.”