Guest Post by Willis Eschenbach
Anthony has highlighted a study by Coughlin and Butler. Their study says that there is little or no urban warming (urban heat island, or UHI) in the temperature record from the Armagh Observatory in Ireland. They say:
It is concluded that temperature observations made at Armagh Observatory have been unaffected by rapid urbanisation over the past three decades.
Why is Armagh important? And is there really no UHI in Armagh?
The Armagh record is very valuable because it is one of the longest well-documented temperature series in existence. Here is the monthly mean temperature record from Armagh. (NOTE: I have replaced the earlier Figures 1 and 3, which only went up to the year 2004, with updated figures which now include 2005-2010. My thanks to those who wrote in with the location of the post-2004 data.)
Figure 1. 209 years of monthly temperatures at Armagh, Ireland. Pale blue is monthly surface air temperatures. Dark blue is Gaussian average of the temperature. Photo is noctilucent clouds over Northern Ireland.
My conclusions from Figure 1?
1. First, one single temperature station says nothing about the temperature of the planet. However, this one says a lot about century-long temperature changes in the North of Ireland.
2. The most striking thing to me is the slow regularity of the two-century-long temperature trend. Yes, there are decadal swings. But they don’t stray far from a simple trendline.
3. The recent warming from ~ 1980 on is not particularly unusual or anomalous compared to earlier periods of warming. From this, however, we can’t tell if there is a heat island signal in the record.
4. The Armagh data shows the same 0.6°C temperature trend over the 20th century that is shown by the global record. It also shows the same features as the global record, warming to the late 1940’s, cooling for thirty years or more, recent warming.
5. There is no sign of any acceleration, and indeed little change at all, in the long slow two centuries of warming.
Oddly, the Armagh Observatory data does not form part of the GHCN dataset that is used by all parties to create global temperature datasets. But I digress. Onward to the UHI.
First, some terminology. “UHI” stands for “Urban Heat Island”. Bad name. There’s lot’s of heat islands that are not urban. Trees, changes in the vegetation of the site, hedges, all of these can cause heat islands. I prefer the term “LHI”, for “Local Heat Island”. I know, I’m swimming uphill, so I call it UHI like everyone else does. But remember it doesn’t have to be urban.
The question of whether Armagh contains a heat island signal is an important one. Casting around for a way to determine the amount (if any) of heat island signal in the Armagh data, I decided to look at the relationship between Armagh temperature and the sea surface temperature (SST) of the North Atlantic and the Irish Sea. I reasoned that for an island on the edge of the North Atlantic, the SST would determine the land temperature. Here are the areas I used to see if my reasoning was correct:
Figure 2. Areas of ocean used for the comparison with the Armagh temperatures. Armagh Observatory is at the center of the yellow house. Left gridsquare is the North Atlantic area. Right gridsquare is the Irish Sea area.
I took the anomalies of the HadISST sea surface temperatures for each of those areas, and of the Armagh temperatures. Here are the results:
Figure 3. Temperature anomalies around Ireland. Monthly averages have been removed. Note that the vertical scale is different from Figure 1. Pale colored lines are actual monthly anomalies, heavy solid color lines are Gaussian averages. Sea surface temperatures (SSTs) are HadISST temperatures from KNMI.
Now, that’s pretty interesting. My observations, in no particular order, are:
1. As I suspected, the ocean temperature around the island of Ireland determines the Armagh temperature. The island is ruled by ocean winds and breezes.
2. The Irish Sea and the North Atlantic temperatures are quite similar. This increases confidence in the precision of the sea surface temperature data.
3. As you would expect, the swings in the land temperature extremes are greater than those of the sea surface temperature.
4. From 1900 to 1986, the averages of all three records are generally all quite close to each other. I always like seeing such a close correspondence of two entirely separate and discrete natural records. It increases the confidence in both datasets. In particular, the wiggle-match between the North Atlantic (heavy red line) and Armagh (heavy blue line) is quite impressive.
5. From 1986 onwards, the Armagh and the ocean datasets diverge in a significant manner.
6. The size of the divergence from 1986 to the end of the record in July 2010 is about a degree.
The Coughlin and Butler paper says:
The grounds surrounding the Observatory and its climate station have remained relatively unchanged over the past 200 years. However, in that time, the town of Armagh has spread in several directions, including to the north and east, past the Observatory site. Much of the development around the site has been in the form of housing built over the past 20-30 years and this development still continues.
Does this mean that Armagh is showing urban or site-specific warming over the last quarter century? I don’t know. But I find it mighty suspicious that after 85 years of running right in sync with both the North Atlantic Ocean and the Irish Sea, the Armagh temperature should suddenly strike out on its own towards new heights, just when the town starts building up around it.
As a result, I’m not prepared to agree with Coughlin and Butler that there is no UHI signal in the Armagh data. They say:
However, recent research into the historical temperature records and comparisons with present day data from rural weather stations indicate that any temperature differences which existed between the Observatory site and the countryside 20-30 years ago have not increased over the intervening years.
Comparison of Armagh with ocean data, however, clearly shows increasing temperature differences in the exact time frame which they have used in their paper to discriminate a valid signal.
My regards to all,
w.
PS – I can’t find any Armagh data after 2004 … does anyone know where it might be available? (Solved, thanks to those who wrote in.)
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Willis
I think you may have jumped to conclusions a bit too quickly. Your analysis seems to be:
Armagh temperatures tracked ocean temperatures fpr several decades until ~1980 when Armagh Obs temperatures began to diverge. Conclusion: UH caused the divergence.
Maybe or maybe not. You need to be aware that temperatures at stations right across the “British Isles” (apologies to the Irish) have risen since ~1980 at a similar rate to those at Armagh. These are in many diverse locations both urban and rural. Have they all undergone urban heating – by the same amount? The temperature station in my own part of the CET region is located in long established area where the population has actually fallen since 1970. If urban heat was a factor it would have have shown up in the immediate post-war period.
I think I’d believe in a reduction in cloud cover before I’d accept UH as the cause for the (UK and Irealnd) warming.
To add to my previous post, i.e.
John Finn says:
August 29, 2010 at 6:29 am
One of the reasons AGW got public support is because everyone right across the country recognised that our winters had become milder and our summers warmer. It was a real effect that we all experienced – not some measured artifact from increased urbanisation.
Willis, I just love your work. I looked at the “wiggle match factor” too when I compared surface station temperature records surrounding Yamal with the treering record, and it was this that made it ridiculously plain that the treering record was quite alien to the rest while the thermometer records had a high correlation factor with each other.
Willis, some more tweaks and I think you have the seeds of a world cracking report.
(1) compare Armagh “wiggle factor” with Loughgall, Annaghmore, and Tandragee -and a couple more if Verity can help
(2) compare Armagh trends and wiggle factors with CET – in the era before UHI problems – and a couple more longterm semi-maritime records if poss
(3) look at the wind factors re Armagh UHI
(4) reference our citizens science work on quantifying UHI eg my refs above to Verity, McKitrick’s work, WUWT “sixth-grader work”,
…and hey presto, you’ve got the start of the real global temperature anomalies record (at temperate maritime NH latitudes) from the LIA until now. All the thousands of pasteurized records are not really needed! IMHO!
Christopher Hanley says:
August 29, 2010 at 3:43 am
I don’t understand why the 200 year Armagh temperature record, in conjunction with the 350 year CET record, cannot be treated as a reasonably accurate proxies for the NH or even global temperature, particularly because they are from a predominantly maritime climate.
http://www.junkscience.com/MSU_Temps/CETvsArmagh_long.html
I’m sure they would be used if it weren’t for the fact that both the CE (Central England) and Armagh
have warmed by more than 1 degree over the past 30 years. This is about twice as much as the surface temperature trend.
You state: “First, one single temperature station says nothing about the temperature of the planet. However, this one says a lot about century-long temperature changes in the North of Ireland.”
However this is not true. While we get the occassional period of high pressure central european weather, most of the time the temperature of the British isles is pretty much controlled by the temperture of the Atlantic. Because the Bering straits are so shallow, a very large proportion of the hot surface water of the Pacific is circulated all the way round to the Arctic for cooling via the Atlantic.
The temperature of the Atlantic is controlled by the temperature of the Pacific. So with a delay of a year or so the Armagh temperature is tracking the average temperature of the Pacific ocean.
Through a stroke of good fortune, the Armagh record, along with the CET from the English midlands (which closely correlate with each other), are not only the longest high quality temperature data records. They are very, very, good proxies for world temperature (recent UHI effects excepted).
Willis, prevailing wind direction is important – it appears that Butler et al are unaware that the prevailing wind across all of Ireland is south-westerly:
“Ireland has a temperate maritime climate that is influenced both by the warm waters of the Gulf Stream and the southwestern winds of the Atlantic Ocean, known as the prevailing winds. The combination of these two factors results in temperatures that remain fairly consistent across the entire country. The Atlantic Ocean influences the moderating effect by absorbing heat in the summer and releasing it during the winter.”
http://bing.search.sympatico.ca/?q=prevailing%20seasonal%20winds%20Armagh%20Northern%20Ireland&mkt=en-ca&setLang=en-CA
Butler et al attribute the lack of UHI effect to there being a playing field contiguous to the north border of the observatory. Meanwhile, the bulk of the city is south and west of the observatory. Since the temperature across virtually the whole island is pretty much the same one could look at recording sites that are north of Irish urban centres and see if they show a bump relative to other sites.
http://wattsupwiththat.com/2010/08/26/uhi-study-of-the-uk-armagh-observatory/
Dear Willis
Professor Manley stops using one of the CET stations because of the urban heat island effect; I am sure you know this.
http://www.rmets.org/pdf/qj74manley.pdf
He also discusses earlier on in the document the effects of hollows etc ie supporting your view on the use of LHI instead of UHI.
If you have already compared the Armagh and CET Data sets I would appreciate a link.
I would have reproduced some of the paragraphs unfortunately the document is an image and not text.
The background color on the graph makes it almost impossible to see the data/trend.
Its interesting to not the max peaks are the same but the min bottoms are not as low.
It isn’t any hotter … it just doesn’t get as cold.
Isn’t that a UHI trademark?
OT
Nature Magazine 27 August 2010
“Cold empties Bolivian rivers of fish
…….wreaking havoc on wildlife, it is unprecedented in recorded history.
…………..linked to the deaths of at least 550 penguins along the coasts of Brazil and thousands of cattle in Paraguay and Brazil, as well as hundreds of people in the region.
Re: my last comment-
It’s blamed on global warming though. :o(
John Finn, you’re just making an argument from analogy, between temperatures at other stations across the isles and temperatures at Armagh. Then you’re assigning causality from the correlation. Your argument is much weaker than Willis’.
Climate physics goes with the greater heat capacity, which is why littoral temperatures are governed by a nearby ocean. Armagh clearly fits that criterion. Willis’ argument also follows Jim Hansen’s empirical correlation of temperatures across 1200 km. Armagh should clearly be influenced by nearby sea surface temperatures on those grounds, too. Willis’ argument follows established climatology. Yours doesn’t.
The question here, lest we forget, concerns the integrity of Armagh’s point-source temperature record. Trends elsewhere, and global or wide-area temperature fields, are an irrelevant distraction.
Hmmm…did they hide the incline?
Sorry, couldn’t help myself.
In the note about the playing fields near Armagh, perhaps the composition has changed. I’ve seen studies on temperature around synthetic playing fields (all the rage in the US) that are significantly warmer than grass (which they call “natural turf”).
Results vary (see links) but 10-20 degrees F warmer than grass with significant heat retention seems common.
So in general, things that *look* like grass may be causing local warming (Synthetic Grass Heat Island effect?). This is a serious issue, as many of us seem to be using satellite imagery to determine grass areas near stations.
Perhaps higher res looking at clarity and color of lines might be a guide? Nearly all synthetic fields in my experience have painted color lines.
See e.g. http://cedb.asce.org/cgi/WWWdisplay.cgi?0705609 (subsurface temps higher, air temp with wind not) and http://www.health.state.ny.us/environmental/outdoors/synthetic_turf/crumb-rubber_infilled/docs/fact_sheet.pdf (reporting on the BYU study and others, with links).
John Finn says:
August 29, 2010 at 6:46 am
“One of the reasons AGW got public support is because everyone right across the country recognised that our winters had become milder and our summers warmer. It was a real effect that we all experienced – not some measured artifact from increased urbanisation.”
I agree. The public at large have short memories regarding the past weather and, at the time the CAGW conjecture was popular, the public trusted science to deal with long term trends.
Unfortunately for the warming hoax, many people did remember that climate scientists in the 1970’s were convinced the next ice-age was starting. Just like today, they had computer climate models to predict the future, which always showed we were heading for ‘snowball earth’.
The number of sceptics has grown since then. People are more interested in climate science now (ironically stimulated by the MSM) and, following the IPCC hockey stick debacle and the CRU Climategate scandal, any remaining trust in climate science has gone.
With a quiet sun, the next few decades will bury this divisive scam as the cold returns across the globe. It’s a pity world governments aren’t building more power stations, especially in the third world, as current capacity will be insufficient to prevent millions of deaths.
Climate is ultimately driven by deterministic chaos, and real climate metrics (100y+) show that Earth’s energy supply systems are constantly oscillating up and down with no discernible trend…
1410-1500 cold – Low Solar Activity(LSA?)-(Sporer minimum)
1510-1600 warm – High Solar Activity(HSA?)
1610-1700 cold – (LSA) (Maunder minimum)
1710-1800 warm – (HSA)
1810-1900 cold – (LSA) (Dalton minimum)
1910-2000 warm – (HSA)
2010-2100 (cold???) – (LSA???)
Well , everybody knows that in Ireland they build their houses out of turf , which is highly insulating , therefore through the long winter months with windows and doors closed the houses leak no heat that could warm the surrounding atmosphere , thats why there is no increase in warmth despite tens of thousands of central heating systems busting their guts to keep the winter cold out . Simplz !!
I hope this is not off topic. I think this is another really good piece of work amongst many others at this site, and several other sites, that present arguments and provoke thinking on climate change. It strikes me however, that little of this work ever stands the test of “proper peer review” outside the really good comments people make, and it rarely leads to publication in “proper journals”. Is it time for Watts Up With That to start an open access online journal of reasoned climate science? Consolidate what is known in one place. Use the valuable contribution of all the comments to make papers stronger and then have the academics and learned people who frequent these sites, or who run them, do the peer review. This will lead to good bullet proof science, if the comments are used to write more robust arguments and give it the credibility of formal publication and peer review. Credible science deserves a home. Do credible reasoned science and publish it in one place to consolidate all the knowledge. Maybe a thought for consideration. Keep up all the good work and all the thought provoking comments.
Here’s a quick-n-dirty fit of the Armagh ‘Storminess’ graph with a sunspot graph for
the same period:
http://ockhamsbungalow.com/blog23/armagh-storm-plus-sun.jpg
Looks pretty close after 1850, not so close before.
Pat Frank says:
August 29, 2010 at 8:16 am
John Finn, you’re just making an argument from analogy, between temperatures at other stations across the isles and temperatures at Armagh. Then you’re assigning causality from the correlation. Your argument is much weaker than Willis’.
My argument is based on the very small statistical probability that each station across the British Isles has been affected by urban heat to the same (or very similar) degree as Armagh. My argument is also based on my experiences in the UK over the past several decades. I think my argument is stronger than Willis’.
“Climate physics goes with the greater heat capacity, which is why littoral temperatures are governed by a nearby ocean. Armagh clearly fits that criterion.”
Although, as Willis demonstrates, the nearby ocean fits it better.
“The question here, lest we forget, concerns the integrity of Armagh’s point-source temperature record.”
And thus uninteresting to anyone who isn’t interested in the weather around Armagh. The question here, lest we forget, are the global trends. Are people forgetting that exercises such as this are to demonstrate the prima facie absurdity of claiming to be able to measure the Global Mean Temperature (which can only be energy in vs. energy out) using a scattering of land based weather stations on this piebald Blue & White planet we inhabit?
As always Willis makes a compelling case in yet another well written piece. UHI is simply not well enough represented in overall calculations.
As well as Armagh we have a wealth of much examined and validated instrumentation (Phil Jones got some EU grants to check some of these out) that record the temperatures during a large part of the LIA which follow the information Willis has posted. I collect them here.
http://climatereason.com/LittleIceAgeThermometers/
These are backed up by numerous observations by scientists, farmers, Presidents, crop records, weather diaries. So whilst we can’t go back into the far depths of time with instrumentation (thermometers) we can still cover a great deal of the Hockey stick timetable and come to a reliable conclusion as to what has been happening.
It is important to put the known climate data into its proper perspective. Willis has shown the Armagh trends-this is CET to 1659 showing trends.
Overall trend;
http://homepage.ntlworld.com/jdrake/Questioning_Climate/_sgg/m2_1.htm
By month;
http://homepage.ntlworld.com/jdrake/Questioning_Climate/_sgg/m2m1_1.htm
As can be seen, throughout the very long record the temperatures have been warming-centuries before the increased input of Co2 by man. From my own research it is clear that the worst excesses of the LIA ended abruptly in 1698. The period around 1700-1730 shows a particularly notable upturn in temperatures.
This instrumental record is backed up by various other records, such as this one from Uppsalla.
http://chiefio.wordpress.com/2009/10/09/how-long-is-a-long-temperature-history/
We are fortunate with this record- from Arrhenius’s home town- to have the botanical garden records as well. These take us back to around 1695. Around 1710 they talk about planting outside some quite exotic plants-together with mulberries.
So the temperature rise can be traced back to at least 1690, and if we look further back, before the English Civil War, we know that the coldest part of this second phase of the LIA ocurred in the early part of the 17th Century, so we can actually trace that rise from around 1620.
I traced part of that long rise from the Dalton minimum of 1812 using Charles Dickens life as a proxy to follow temperature trends.
http://noconsensus.wordpress.com/2010/01/06/bah-humbug/
The modern GISS record from 1880 merely ‘plugs’ into the end of this well documented slow and gentle rise. The Giss record curiously starts from a known trough in temperatures around 1880-if Hansen had taken the previous decades records, when there was a notable peak, the slope would not be as high as is commonly shown. I have commented on this in various of my articles including this one;
“Article: Three long temperature records in USA. Author: Tony Brown
This article links three long temperature records along the Hudson river in the USA. They illustrate that a start date of 1880 (Giss) misses out on the preceding warm climatic cycles and that UHI is a big factor in the increasingly urbanised temperature data sets from both Giss and Hadley/Cru
http://noconsensus.wordpress.com/2009/11/25/triplets-on-the-hudson-river/#comment-13064
To demonstrate that this rise wasn’t limited to Armagh or CET here are additional linear regressions for some of the oldest data sets in the world-all show the same slight warming trend over centuries.
http://i47.tinypic.com/2zgt4ly.jpg
http://i45.tinypic.com/125rs3m.jpg
Our datasets demonstrate that rather than warming, we are becoming ‘less cold’ as we move away from severe LIA winters which depressed overall mean temperatures by 1 or 2 degrees C in some years and the increae of night temperatures in particular is a well known UHI trait.
This link here demonstrates the abeyance of severe winters (graph 3)
http://mclean.ch/climate/England_Scotland.htm
This one here demonstrates the relative constancy of summers compared to winters.
http://climate4you.com/CentralEnglandTemperatureSince1659.htm
This all suggests to me that CO2 is a very weak climate driver that is overwhelmed by natural variability. It also suggests to me that we have become fixated on the 1880 records and not made enough effort to find out what has gone on prior to this date. I think it is little known generally that the world was warming (albeit in fits and starts) 200 years prior to the time James Hansen commenced his records.
To me the really interesting question is what caused these short sharp and severe LIA interludes (which by no means occurred every year) which were interspersed with periods nearly as warm as today? Could the circumstances recurr? Are we now so fixated on CAGW that we couldn’t cope with substantial cooling?
Tonyb
pwl says:
August 29, 2010 at 1:56 am
Yes, I know I should publish in the journals. However:
1. I hate translating my work into Scientese. I always feel like I have to give myself a lobotomy to do it.
2. Time. I can publish here while the issue is hot, while it would likely take six months or longer to get it into the journals.
3. Readership. Lots and lots and lots of folks read WUWT, compared to say the IJoC. I can reach many more people that way. In particular, I can reach non-scientists and scientists from other disciplines.
4. Readership. Scientists read WUWT. And while my work here is not peer-reviewed in the ordinary sense, the opportunity exists for all readers to peer-review it. As a result of the informed readership here, the quality of the review is often higher at WUWT than in the journals.
5. Time. Time spent writing for the journals is time I don’t have available to do research. Unlike academics, I don’t have to publish or perish.
Finally, I am pushing for a change in the scientific method, from a journal-based method to a more transparent, open, rapid, interactive web-based method. I can best do so from here.
John Finn says:
August 29, 2010 at 6:29 am
Well, in short … no. First, I have not said definitively that it was UHI, because glitches in the sea temperatures need to be considered in the differential diagnosis.
Second, I kept waiting for you to provide a citation or a graph or something, anything, that shows that stations across the UK and Ireland are all warming in the same fashion as Armagh, that is to say, moving in very close sync with the ocean for 85 years, and then warming since then. Please get back to us with something to support your assertions, because up ’til now you are speaking from a data-free zone …
Willis Eschenbach says: “. . .my work here is not peer-reviewed in the ordinary sense . . .”
An ordinary sense which has become a wrong sense, which is what has made it so easy to twist it, but then you seem to be aware of that. Slashdot, Digg and Kuro5hin all point to ways in the which the process might be better handled by an online journal; although it’s worth noting that wikis point to reasons for the genesis of the current system. It at least started out with intentions similar to your own, but things that are not refreshed grow stale; and in the long term may even begin to rot.
Maybe it would make sense to think in terms of urban heat “bubbles” rather than “islands”. Warm air generated by urban areas might exhibit the character of a bubble which can be blown by winds. If this is the case, it might shift such bubbles to periodically influence areas outside the urban areas, enough to raise average temperatures.