JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, D14113, 12 PP., 2011
Observed surface warming induced by urbanization in east China
- The rapid urbanization has significant impacts on temperature over east China
- A new method was developed to dynamically classify urban and rural stations
- Comparison of the trends of UHI effects by using OMR and UMR approaches
Xuchao Yang, Shanghai Typhoon Institute of China Meteorological Administration, Shanghai, China Institute of Meteorological Sciences, Zhejiang Meteorological Bureau, Hangzhou, China Yiling Hou, Shanghai Climate Center, Shanghai, China, Baode Chen, Shanghai Typhoon Institute of China Meteorological Administration, Shanghai, China
Monthly mean surface air temperature data from 463 meteorological stations, including those from the 1981–2007 ordinary and national basic reference surface stations in east China and from the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, are used to investigate the effect of rapid urbanization on temperature change.
These stations are dynamically classified into six categories, namely, metropolis, large city, medium-sized city, small city, suburban, and rural, using satellite-measured nighttime light imagery and population census data. Both observation minus reanalysis (OMR) and urban minus rural (UMR) methods are utilized to detect surface air temperature change induced by urbanization. With objective and dynamic station classification, the observed and reanalyzed temperature changes over rural areas show good agreement, indicating that the reanalysis can effectively capture regional rural temperature trends. The trends of urban heat island (UHI) effects, determined using OMR and UMR approaches, are generally consistent and indicate that rapid urbanization has a significant influence on surface warming over east China. Overall, UHI effects contribute 24.2% to regional average warming trends. The strongest effect of urbanization on annual mean surface air temperature trends occurs over the metropolis and large city stations, with corresponding contributions of about 44% and 35% to total warming, respectively. The UHI trends are 0.398°C and 0.26°C decade−1. The most substantial UHI effect occurred after the early 2000s, implying a significant effect of rapid urbanization on surface air temperature change during this period.
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the australian labour gov,t has stooped to a low low act they have visited nursing homes and retirement villages and told them that due to sea level rise they will all be under water and will have to move to higher ground, this to me is a low act ? what do you think of this act
But UHI is factored out of global trends isn’t it? Maybe.
I thought the real question was the extent of overall socioeconomic impact on temperature trends.. UHI is only one component in the total mix. At least this is what I take from the papers coauthored by Ross McKitrick.
This paper appears to reconfirm what many suspect, namely that UH is significant AND it has played a part in the recent appearance of warming these past 30 years or so.
I know that we will soon see a number of the ‘usual’ posts suggesting that since we are looking at anomalies and not absolute temperatures, the overall trend is unaffected and that the statistic of large numbers cancels these anomalies out. Personally, I consider such arguments to be bunkum although I do accept that once a temperature measuring station has been fully swamped (saturated) by the effects of urbanisation, thereafter, but only thereafter, the anomalies will become little affected by UHI. .
It may be the case that in stable urbanisations, UHI, whilst having an effect on absolute temperature, has little effect on anomalies. This begs the question; when and which urbaisations are truly stable? In the UK, for example, there has been much urban sprawl since the 1950s AND there have been many new towns being built in what were once rural locations. Even in the Capital, as regards places like Kew Gardens and Heathrow, which are used for temperature measurements, these are very different places to what they use to be in the 1940s and 1950s. Likewise, areas that were once war time air strips are now radicially different and even in places which are not growing laterally, they are growing upwards with ever increasing high rise buildings. Just think how office blocks have changed these past 50 or so years with better heating, better aircon and often with electric lights left on 24/7. The idea that this is not ‘polluting’ the temperature record is niaive at best, if not damn right facetious.
Further, even if surburbia has not changed much in area, life style has certainly changed these last 40 or 50 years and these life style changes are also have an effect.. For example in the UK, back in the 1950s, central heating was extremely unusual, now it is almost universal. In the UK, houses are not well insulated and they must be pumping out much heat which was not being produced in the 1950s. Gardens which were once laid with lawn and flower beds, have been paved over to be used as parking spaces for cars which paved areas now act as storage heaters radiating warmth in the evenning.. Indeed, the increase in car use alone adds to the temperature (just think of all the hot engines coming home at 7 to 9pm at night and giving off heat for many hours). Shops and businesses which once closed at 5pm and were not open at all at the weekend, are now open 24/7. The reality is that semi-rural and surburban life style is very different compared to just 40 or 50 years ago and this is playing a role in the recent ‘apparent’ land based temperature record.
In fact, one probably only needs to look at how energy consumption has increased, these past 50 years or so, to see how much development there has been, and how much additional heat energy is being pumped into the general vacinity and which inevitably is being picked up by temperature measurement stations and is influencing the temperatures recorded.
These type of research is very useful and in turn it means that there needs to be a close and careful re-examination of the temperature record to check and see how and whether adjustments for UHI are being properly and rigourously being made. , .
@tango says: July 28, 2011 at 2:24 am
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Perhaps these nursing homes, will use water beds!
No, seriously, if true, it is disgraceful since it is likely to cause distress to people who are already vulnerable, and who may not fully understand the complete BS that they are being told.
There is presently no alarming sea level rise, and there is no real reason to consider that it will, in the near future, suddenly and rapidly rise at a rate very significantly higher than the 2-3mm per year rise which we are currently observing.
The ‘warmists’ are telling BS about sea level rise but unfortunately the press like to run with stories of impending doom and disaster. Somehow, this one and very important fact (namely that alrming sea level rise is BS) has got to be got accross to the MSM and public at large.
Stitch that, Phil Jones.
richard verney says:
July 28, 2011 at 2:39 am
An interesting statement, do you have any studies that illustrate the idea or is it pure conjecture on your part. I’ve only seen studies showing that the trends are the same in both rural and urban site over the last ~50 years in both China and the UK.
tango says:
July 28, 2011 at 2:24 am
the australian labour gov,t has stooped to a low low act they have visited nursing homes and retirement villages and told them that due to sea level rise they will all be under water and will have to move to higher ground, this to me is a low act ? what do you think of this act
Is there a tsunami on the way?
It is despicable. They appear to be totally off their rockers. This shows that most politicians havn’t got a clue about the real world and belive everything they read in the papers.They should be concentrating on the global finace crises because thats real!. It easy to give advice on fiction.
The UHI trends are 0.398°C and 0.26°C decade−1.
Hmmm, didn’t the IPCC use a UHI estimate of 0.01C per decade?
Tango,
Exactly who in the Labor (not Labour) government visited what nursing homes and retirement villages and when ? Sounds a bit alarmist to me.
tango says:
July 28, 2011 at 2:24 am
I think moderators should delete all off topic comments in the first 24 hours of a new post.
While WUWT might benefit from an open topic thread, I think people like you would still look for a new post and try to hijack the discussion early on.
Trends of this magnitiude are important and it is an area that needs thorough investigation. Unifortunately claims of the contamination of ‘global average temperature’ by UHI are readily countered by those who point out that plotting all the rural stations worldwide separately (Zeke Hausefather posted this over at The Blackboard IIRC) gives the same shape of graph and the same trend as the complete set of urban and rural stations.
Stations are treated completely objectively and any alterations to them again use objective means (such as nightlights e.g. this publication, also see http://diggingintheclay.wordpress.com/2010/04/06/nightlights-and-shifting-sands/
http://diggingintheclay.wordpress.com/2010/07/10/gistemp-plus-ca-change-plus-cest-la-meme-chose/).
Much as I hesitate to say that scientists should be in any way subjective, there is a need to look in detail at individual stations, much as Anthony has done with http://www.surfacestations.org/. Having done a lot of peering at individual stations on Google Earth etc, there is a lot of change in small rural stations, land use changes, growth of small towns… These require attention – individually to sort out possible effects.
The definition of ‘rural’ for GIStemp is a population of >10,000, (also airports are frequently classed as rural) yet studies like Roy Spencer’s http://www.drroyspencer.com/2010/03/the-global-average-urban-heat-island-effect-in-2000-estimated-from-station-temperatures-and-population-density-data/ show that there is a greater effect when increasing population density at the lower end of the population scale than in areas with already medium or high density.
I cannot believe it is taking this long for people to realize that UHI is the ‘global warming’ of recent decades. I have been saying this for years. I live in the country and the stations around me show zero warming over the past 100+ years, yet the cities around me do. Add the fact that the GHCN network has been ‘tweaked’ to be urban biased and you have AGW. Now can we please get back to real science?
Tallbloke writes, “Stitch that, Phil Jones.”
Jones has written that the UHI effect is quite small and is part of why the IPCC AR4 wrote:
“Studies that have looked at hemispheric and global scales conclude that any urban-related trend is an order of magnitude smaller than decadal and longer time-scale trends evident in the series (e.g., Jones et al., 1990; Peterson et al., 1999).”
There were questions raised about the China data, and Jones later came around to the UHI side, agreeing with higher estimates, writing “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.”
Urbanization effects in large-scale temperature records, with an emphasis on China
http://www.agu.org/pubs/crossref/2008/2008JD009916.shtml
This UHI effect thus accounts for 40% of the measured warming.
Another proof for Dr. Pielke Sr? He maintains that the A in AGW is more then just CO2. Even building our cities up is still a human factor in the rising temps of the past couple hundred years.
This is the kind of thing missed by GISS, Steve Mosher and others in their statistical illustrations that purport to show that we can neglect large numbers of stations and UHI is not really a factor. The TREND of urbanization adds a TREND on to The trend and results in overall avg increase across a country. Have the Chinese got this wrong? I know many things can be counter-intuitive but sometimes common sense can be right, too.
Kelvin Vaughan says:
July 28, 2011 at 3:47 am
“….This shows that most politicians haven’t got a clue about the real world and beleive everything they read in the papers…”
They don’t need a clue, and could probably care less about what it or is not true. All they need is an agenda. Anything said or done is performed only to support the agenda. Everything else is superfluous. (truth, integrity, honor, dignity etc.)
There is nothing “common” about Common Sense in the 21st Century. It’s more rare than Gold. UH is THE Missing Link in the AGW Mumbo-Jumbo Hoop-La; it has been since AGW was first created. Of course one does have to subtract the natural rise in global heat following the Little Ice Age, which technically hasn’t ended, but which some think ended in the late 19th or early 20th centuries. Oh well, that’s why history books never go out of style. People always love to read how stupid their parents and grandys and greats were. Of course too much history is not good for the soul and leaves a pessimistic taste in your mouth too.
Rob R-Yup, urbanization is just one potential source of bias. I think the satellite data can bound this and all other sources of bias to a total of about one third of the observed trend over the whole Earth in the last thirty years. Over land the amount is larger.
Studies of particular effects can be helpful, however, in identifying the specific reasons for the apparent biases in the data.
But, but, but, true to form the BBC in the UK was giving priority to some loons who are rowing to the North Pole. It had all the usual trimmings too, disappearing ice, how different it looks and, incredibly, how hot it is in the Arctic Circle!
Nearly choked on my coffee.
Meanwhile, here on the windward side of the North American continent: RIGHT NOW NEXT WORK WEEK IS SHAPING UP WITH COOLER THAN NORMAL TEMPERATURES
We’ve got the first fall leaves showing up. Among the non natives, birches, apples and some others I can’t ID. Among natives the usual and normal early ones – big leaf maples, buckeyes (nearly bare now per normal) and cottonwoods, and abnormally – willows and black oaks.
Professor Wei-Chyung Wang of the State University of New York at Albany will probably have no comment on this story.
And I’m sure Professor Wei-Chyung Wang of the State University of New York at Albany will continue to withhold the temperature measurement locations that he used to claim that UHI was minimal in China.
http://wattsupwiththat.com/2010/02/01/climategate-intensifies-jones-and-wang-hid-chinese-station-data-issues/
richard verney says:
July 28, 2011 at 2:39 am
=====================
Even in long urbanized areas, energy flux has likely increased ongoing even after urbanization. In 1950 almost no one had air conditioning and the only “devices” were generally related to lighting, with a few others in sporadic usage (appliances). Today, electronics, machines and gadgets are ubiquitous and widely deployed both in and out doors.
SteveE says:
July 28, 2011 at 3:35 am
An interesting statement, … I’ve only seen studies showing that the trends are the same in both rural and urban site over the last ~50 years in both China….
Interesting statement. What studies other than the one that involved Professor Wei-Chyung Wang of the State University of New York at Albany?
@ur momisugly gator69 says “I cannot believe it is taking this long for people to realize that UHI is the ‘global warming’ of recent decades.”
That is not what this paper says – the paper indicates that UHI in urban areas needs to be considered, but even then 75.8% of the warming is from other sources.
Also – as noted above it is the anomaly that matters over time.
Verity Jones says:
July 28, 2011 at 6:02 am
Studies have shown that even small populations near a temperature sensor can and do affect the reading. On the other hand, the IPCC seems to consider any town smaller than 100,000 to be rural.