New paper: Urbanization has increased minimum temperatures 1.7K in the UK

From the Royal Meteorological Society. (h/t to reader NJSnowFan)

How much has urbanisation affected United Kingdom temperatures?

Ian L. M. Goddard, Simon F. B. Tett

Abstract

This study aims to estimate the affect of urbanisation on daily maximum and minimum temperatures in the United Kingdom. Urban fractions were calculated for 10 km × 10 km areas surrounding meteorological weather stations. Using robust regression a linear relationship between urban fraction and temperature difference between station measurements and ERA‐Interim reanalysis temperatures was estimated.

For an urban fraction of 1.0, the daily minimum 2‐m temperature was estimated to increase by 1.90 ± 0.88 K while the daily maximum temperature was not significantly affected by urbanisation. This result was then applied to the whole United Kingdom with a maximum T min urban heat island intensity (UHII) of about 1.7K in London and with many UK cities having T min UHIIs above one degree.

This paper finds through the method of observation minus reanalysis that urbanisation has significantly increased the daily minimum 2‐m temperature in the United Kingdom by up to 1.70 K.

1 INTRODUCTION

The urban heat island intensity (UHII), which describes increased temperatures in urban areas, has long been known and attempts have been made to quantify it for many years (Mitchell, 1961; Oke, 1982). The urban heat island (UHI) develops through changes to the surface energy balance due to anthropogenic modifications to the land surface. The importance of understanding how these changes will affect the global climate and the potential bias to land temperature records arising from urbanisation has piqued interest in this area of research. Further, due to the consequences of increasing temperatures in urban areas, such as increasing air pollution and mortality rates (Johnson et al., 2005; Stedman, 2004), many studies have attempted to quantify how temperatures in highly urbanised areas will be affected by increasing urbanisation.

Previous studies have generally concluded that urban warming has had a negligible effect on global scale temperature series (Peterson et al., 1999; Parker, 2004). For example, Jones et al.(1990) showed that the urban warming effect corresponds to no more than 0.1 K over the last century. However on regional scales, the affect of urbanisation on temperature may be significant. Specifically in China, where there has been large expansion of urban areas, a significant effect has been estimated. Yan et al. (2010) concluded a large impact of urbanisation up to 0.54 K/decade on local temperature series in Beijing. Whilst Zhou et al.(2004) showed a smaller urban effect of about 0.05 K/decade in south east China.

This effect is not exclusive to Asia, several studies have found similar effects in Europe and parts of the United Kingdom (Emmanuel and Krüger, 2012; Grawe et al.2013; Trusilova et al.2008; Chrysanthou et al.2014). To quantify the UHII, Trusilova et al. 2008 and Grawe et al. (2013) both used atmospheric models to estimate the effect of urbanisation on temperatures in mainland Europe and the greater London area respectively. In Europe, Trusilova et al. (2008) quantified an average increase in the daily minimum temperature (equation/asl2896-math-0001.png) of 1.53 ± 0.49 K and observed that the maximum daily temperature (equation/asl2896-math-0002.png) may increase or decrease depending on local climate. They reported that in cooler climates equation/asl2896-math-0003.png increased due to urbanisation. In the greater London area Grawe et al. (2013) found an average increase in (equation/asl2896-math-0004.png) and (equation/asl2896-math-0005.png) of 1.31 ± 0.30 and 0.57 ± 0.19 K respectively. Further, through the comparison of recorded minimum and maximum daily temperatures between urban and rural sites, Emmanuel and Krüger (2012) found for Glasgow, consistent with other studies, an average increase of 1.6 ± 1.2 and 0.8 ± 2.1 K in equation/asl2896-math-0006.png and equation/asl2896-math-0007.png respectively. The aim of this study is to estimate the impact of urbanisation across the entire United Kingdom.

Previous studies have used varying methods to quantify the impact of urbanisation on temperature. Yan et al. (2010) measured the significance of urbanisation by comparing temperature time series for urban and rural weather stations, observing a greater warming at urban sites. However, it is difficult to classify weather stations as either urban or rural. In their study Yan et al. (2010) used population density as a marker for urbanisation. However, this data is often out of date and can be hard to obtain for rural areas (Wang and Chen, 2016). Satellite data has also been used to asses the urbanisation of an area. Hansen et al.(2001) used satellite measurements of night‐time light emissions to classify weather stations as either urban, semiurban or rural; where a station classed as urban was located in a bright area, a semiurban station was located in a dimly lit area and a rural station in an unlit area. However, a problem with this method is that stations classed as urban may be located inside well lit city parks, where the UHII is reduced by the park cool island (PCI) effect (Cao et al.,2010). The PCI effect, caused by radiative exchanges with vegetation and its surroundings, partially mitigates the development of the UHI (Oliveira et al., 2011). Hence, using night‐time light emission data to characterise stations as urban or nonurban may lead to inaccurately characterising the effects of urban material on temperature. This study aims to deal with the problem of PCI mitigation of the UHI and the issues of urban/rural classification by determining the degree of urbanisation of a given weather station, rather than having discrete classes. This is done through the use of a land cover/land use dataset derived from satellite images to asses the fraction of urban material around weather stations (termed urban fraction).

We next detail the data and methodology used to determine both the degree of urbanisation of weather stations in the United Kingdom and the corresponding urbanisation effect. The results of the analysis are then reported before some discussion of the results and conclusions are given. This study finds there is no significant urban effect on the daily maximum 2‐m temperature but does find a significant increase in the daily minimum 2‐m temperature due to urbanisation.

3 RESULTS

We generally find weak and statistically insignificant relationships between monthly, seasonally or annually averaged ΔT max and urban fraction (Figure 3). When ΔT max is averaged annually, the linear relationship between this and urban fraction is insignificant (at a 97.7% confidence level) at 0.25 ± 0.42 K. The strongest relationships are observed in the winter months with December having an urbanisation effect of 0.67 ± 0.34 K. However, this relationship is insignificant for February through to October. The results suggest that urbanisation has had no significant impact on daily maximum temperature across most of the annual cycle.



Figure 3 Robust linear regression between ΔT max (red) and ΔT min (blue), and urban fraction. The y‐axis is the regression coefficient of ΔT max or ΔT min against urban fraction which we denote as the UHII. The x‐axis shows the period over which ΔT max or ΔT min was averaged. The black dashed line shows zero regression coefficient. Uncertainty estimates (vertical lines) are 2σ errors. The solid black vertical line separates the months from the seasonal and annual results

A significant increase in monthly, seasonally and annually averaged ΔT min is observed in areas of higher urban fraction. For annual average ΔT min, an urbanisation effect of 1.90 ± 0.88 K is found (Figure 3). Stronger relationships are found for ΔT min in the summer months where the maximum UHII reaches 2.17 ± 0.78 K in May.

We have used our results to generate a map of the change in T min due to urban material in the United Kingdom at the 10 km × 10 km scale (Figure 5). We define the UHII as the maximum change in temperature due to urbanisation within the city boundaries and we observe the largest UHII in central London with considerable UHIIs in many other cities. Refer to the Supporting Information for a table of the calculated UHIs of several major cities in the United Kingdom (Table S2).


Figure 5 Map showing the change in T min due to the urbanisation at the 10 km × 10 km scale over the United Kingdom and Ireland. The colour bar shows the magnitude of the temperature change in K

4 DISCUSSION AND CONCLUSIONS

The observed increase in T min can be attributed to an increased intensity of the UHI during the hours after sunset and into the night. Many studies have previously shown that UHII is maximised during the night (Arifwidodo and Tanaka, 2015; Montávez et al.2000; Ripley et al.1996). The intensity is maximised during these hours, as heat absorbed by urban structures will be re‐radiated back into the atmosphere at a slower rate, due to smaller sky views, than natural structures. Further, the increase in impervious surface in an urban area causes a reduction of the latent heat flux and a rise in the sensible heat flux (Zhou et al.,2014). This leads to a difference between the rates at which the urban and natural area will cool during the night, with urban areas sustaining a higher temperature into the night. With minimum temperatures often occurring at night, the slowed rate of cooling in urban areas results in an increase of the observed minimum temperature.

The reduced effect seen in T max may be the result of partial shading (reduced sky‐view factor) in urban areas. If less short wave radiation is absorbed in an urban area than in rural areas, we expect that during the daytime the UHII will be smaller than at night and in some cases has been shown to be negative (Trusilova et al., 2008). Further, the reduced effect may be attributed to higher storage in the day time energy budget of the urban over rural areas. Increased storage leads to less day time sensible heat flux in the urban area causing a reduced increase in temperature. Hence, we observe a smaller difference between the urban and rural temperatures and thus a lower UHII.

The results indicate some seasonal variability in the magnitude of the increase in both T minand T max. Our results for T min agree with previous literature, showing that the UHII is larger in summer than in winter (Kłysik and Fortuniak, 1999; Philandras et al.1999). This may be due to increased wind and cloud cover in the colder seasons resulting in more mixing of the atmospheric boundary layer and less available short wave radiation. Both of these factors would act to reduce the magnitude of the UHII. Further we observe a significant effect on Tmax only in winter (Figure 3), possibly due to anthropogenic heating leading to a warmer climate in urban areas.

Unlike the studies performed by Wang et al. (2017); Yan et al. (2010); Zhou et al. (2004); Chrysanthou et al. (2014); who performed studies on the rate of warming against urbanisation rate, this study looked only at differences in recorded and reanalysis temperature data and not the rate at which they are changing with respect to one another. Analysis of older land use data sets (CLC 2000, CLC 2006) found no urbanisation changes in the regions around the weather stations used in the study suggesting that there has been no significant urbanisation changes in the United Kingdom since 2000.

In this study, relationships between the urban fraction around weather stations in the United Kingdom and temperature differences between observed and reanalysis values were examined. A small and statistically insignificant relationship was observed for T max. After performing several sensitivity tests, it was found that in almost all cases the result remained insignificant and even when significant, the effect was very weak. This is in contrast to the results for T min where urbanisation has caused significant warming. The results indicate that if an area is 100% urbanised, annual averge T min would have increased by 1.90 ± 0.88 K. The results of the sensitivity tests suggest that whilst this value may be a slight under‐estimate, the significance of the result is robust in most cases. We observe that when considering an area of 400 km2 over 100 km2 the effect may be increased, suggesting that a larger area may influence the UHII more than originally proposed in this study. The relationship found for Tmin in this study is in agreement with the results found by Trusilova et al. (2008) and shows a slightly stronger relationship than that found by Grawe et al. (2013). However, the results from this study show a slight, and largely insignificant, increase in T max due to urbanisation. Whilst the results are likely dependent on the ERA‐interim data used for the analysis, we see that the results are consistent with previous literature, where a weaker relationship between urbanisation and T max than in T min is found (Wang et al., 2017; Trusilova et al.2008). Albeit, our study does not capture as large an effect in T max as the cited literature.

The full paper: (open access)
https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.896


This is not unlike what our surfacestations project has found in the USA:

Press Release – Watts at #AGU15 The quality of temperature station siting matters for temperature trends

NEW STUDY OF NOAA’S U.S. CLIMATE NETWORK SHOWS A LOWER 30-YEAR TEMPERATURE TREND WHEN HIGH QUALITY TEMPERATURE STATIONS UNPERTURBED BY URBANIZATION ARE CONSIDERED

Figure4-poster

Figure 4 – Comparisons of 30 year trend for compliant Class 1,2 USHCN stations to non-compliant, Class 3,4,5 USHCN stations to NOAA final adjusted V2.5 USHCN data in the Continental United States

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132 thoughts on “New paper: Urbanization has increased minimum temperatures 1.7K in the UK

  1. “Urbanization has increased minimum temperatures 1.7K in the UK”
    No Sh*t Sherlock

    It is not just urbanization but also land drainage and water extraction as dry land heats up quicker.

    • It is not just urbanization but also land drainage and water extraction as dry land heats up quicker

      I didn’t think of this before, but it is true that urban and semi-urban European areas have a good drainage, which you can measure here in north as mosquito density as well. The urban areas have nice underground ditches, which of course prevent top soil (well, asphalt) being moist during dry seasons. This will change the latent heat flux as they said.

      The increase in ditching and plumbing during the 20th century was phenomenal here. And it still continues as new areas are developed.

      I wonder how the temp trends change if you only use sites that still suffer from mosquitos? 🙂

      • For the past 30 years or so it has been an obvious fact to me that the construction of highways, roadways and streets in urban, semi-urban and rural areas …. also includes ditching and plumbing (culverts), all of which GREATLY exacerbates land drainage, water extraction, water table reduction and stream/river water level reduction.

        With ditches and culverts along all roadways, ….. rainwater and snowmelt is quickly collected by aforesaid and deposited into river channels where it quickly flows to the sea.

  2. If I were a betting man I would bet that asphalt, bricks, and concrete have had far more impact on rising world temperatures since the beginning of the industrial age than CO2.

    • global warming theory predicted that night temps would get warmer….

      ..don’t think they didn’t know what they were doing…..CYA

    • Dave, I think your comment should be qualified by the insertion of “impression” – asphalt, bricks and concrete have led to higher urban temperatures which have been used to create the “impression” of rising global temperatures across the extra-urban (rural) areas across the UK .

      As the colour coded map shows there has been somewhere between 0c and 0.1c change in UK temps over what looks to be 99.9%++ of the non-urban land mass …….

      weather forecasts routinely warn that overnight rural temperatures outside London in the winter will be 3 or even 4C COLDER than London !!!

      • Not just in the winter. Driving out from the London suburbs I have seen the temperature on my car thermometer reduce by 5 – yes FIVE – degrees in summer by the time my 45 minute journey ended. And on a winter occasion I drove 8 miles to Gatwick airport boundary and on heading home I noticed it was now 2C as opposed to freezing at home. Driving the 8 miles back the temp dropped back to -1C. No wonder they love airports for their fiction. Over the period of the global warming myth, how much has traffic increased at Gatwick airport and don’t forget the change of type of aircraft. No more propjets.

        • On many a summer’s day here at the confluence of the Mississippi and Illinois there can be several degrees difference between a paddock and the wooded creek hollow adjacent. If the sun is out and the wind is blowing the thermometers outside the front and rear of my house can also differ considerably. The humidity is usually high here, so a couple degrees can feel like alot.

          • I live well within the city limits of Portland Oregon. a few blocks away is a several hundred acre wildlife refuge. The proximity of that wildlife refuge will ensure that on clear calm nights my low temperature will be up to 5F cooler than the rest of the city. I wonder where their readings were taken, next to the tarmac?

  3. But the UKMO have a 0.1°C adjustment for urbanisation, don’t they? Isn’t that what Richard Betts said

    • Stephen

      The Met Office use a 0.2C adjustment but they are currently re-examining that to see if they should allow more. That is for CET.

      This from their web site

      “Both series are now kept up to date by the Climate Data Monitoring section of the Hadley Centre, Met Office. Since 1974 the data have been adjusted to allow for urban warming: currently a correction of -0.2 °C is applied to mean temperatures”

      They make no uhi adjustments for the usual records most commonly used, which are the composite ones from 2010 covering all four home countries..

      With that criteria 2018 tied with 3 others as the hottest summers ever using the 1910 records but CET, which is more consistent in its use of stations, was still notably warmer. The difference is that the 1910 records are not adjusted for UHI.

      I have been exchanging a number of emails with the Met office regarding these figures. It has been over a year since they started looking again at uhi so lets hope they come up with some pronouncement soon

      tonyb

      • Tony, I find the tenths of a degree adjustement criteria completely laughable in relation to the UHI affect. The UK Met OffIce sponsored weather forecasts regularly differentiate between close proximity city and rural temps in whole degrees, not tenths. Up to a 5 degrees C differential is not uncommon, particularly in winter. And Britain is a very small island. Take out the airport and city weather stations and compromised sites and what have we got? In a century, and outside the still small percentage of land occupied by dwellings and industry, the Brits have possibly witnessed a temperature increase that is commensurate with the variation in temps one would expect between your ankles and your ears on a hike up a small hill. Cue apocalypse!

    • This effect is tied to urban fraction.

      any one here know the urban fraction for CET?

      nope

      • But we do know that it has not blossomed into a metropolis. Ant the effect is much more complicated than simply urban fraction. Probably tied to type of building, %pavement, asphalt or concrete?, may not be a linear function of population density, etc. Perhaps your team could study it and elucidate the rest of us. This is actually a serious proposal. When you apply a correction that is significantly larger than the effect we a re trying to quantify, some research should go into how this correction is determined. If this has not been done well, it is time to do it well.

        • “But we do know that it has not blossomed into a metropolis. Ant the effect is much more complicated than simply urban fraction. Probably tied to type of building, %pavement, asphalt or concrete?,

          really? have you looked at the muliple sites that constitue CET? or are you just assuming?
          Yes, of course the effect MIGHT BE more complicated. But the secondary factors
          would be things like building height, “compactness” of the urban fraction and
          the scale length rather than the percentage of urban cover. In addition, the presence
          of water ( park ponds, rivers) decreases the UHI and green areas and tres likewise
          reduce the effect. Today we also study UCI, urban cool islands.

          “may not be a linear function of population density, etc. Perhaps your team could study it and elucidate the rest of us. This is actually a serious proposal. When you apply a correction that is significantly larger than the effect we a re trying to quantify, some research should go into how this correction is determined. If this has not been done well, it is time to do it well.”

          A) we did study it, published in fact.
          B) I’ve continued to study it for the past 7 years, LOCALLY you can find UHI in
          large cities. At small urban fractions it is hard to detect. Most sites have small
          urban fractions
          C) There are several paths to correct for it. The easy way is to eliminate the stations
          with ANY urban fractions. Did that, the result is……..
          Its still warming. there was an LIA

          I do have a new analysis using urban fraction for the entire globe. its interesting
          but confirms what we already know. the effect of UHI on the Global record is small.

          • Steven,
            Quite a number of authors have chipped away at the UHI problem. Most have added little bits of progress to the story, but the story is far from a comprehensive explanation. In times of such uncertainty, it is simply wrong science to create and use adjustments to cope with a person’s current understanding of what is favored by him/her. There was, for example, no value in using a night lights correction, except to demonstrate it did not work, because not enough research had been done to call our understanding comprehensive and complete enough to allow adjustments.
            The UHI effect is complicated. Here is just one more piece of the puzzle.
            Rather than using time, I have been putting station altitude on the X-axis of temperature graphs. The first finding, new to me, was that both Tmax and Tmin are sensitive to station altitude by more than simply a lapse rate mechanism.
            Plausibly, weather stations on high peaks have fewer clouds above them so night-time radiation can escape to space more easily, leading to more rapid night cooling and possibly to lower minima. Let us assume this to be the case for stations without UHI. If UHI is present, does this effect show itself in any systematic way that eventually could be rectified by adjustment?
            Unfortunately, Australian data I am using here has very few stations sitting high above the clouds and none with human development as extensive as many major cities down near sea level. Therefore, this altitude effect might be more useful to examine UHI mechanisms than to be the basis for a method of UHI adjustment/correction. I do not know, I do not have enough data before me.

            The point is that it is completely wrong to impose corrections on existing data while new effects are still being uncovered. Night lights, what value are they when some stations are above low cloud and some below, but it all changes next night? Or next hour?

            IMHO, there have been too many confident charges at the gate of understanding UHI but very little progress. This is largely because people are trying to cobble together adjustment schemes from old, poorly controlled data when the topic is crying out for a number of planned, coordinated experiments in real time to tease out the significant factors that affect UHI.

            You might know that our BOM has released Version 2 of the official national temperature data set. The temperature data of every one of the 114 stations has been adjusted more than once. That nice little effect of temperature relation to altitude shows up strongly in raw data, but it is eliminated with surgical precision in Acorn Version 2 by adjustments that seem to be accidental and unexplained, unless the BOM has noted this effect without mentioning it. If all this is so – it is still being investigated – it shows once more the poor science of making adjustments when there are further effects still being discovered. Kids get away with that approach, but senior scientists are urged to hand in their badges.
            Geoff.

          • Steven Mosher – March 31, 2019 at 7:11 pm

            In addition, the presence of water ( park ponds, rivers) decreases the UHI and green areas and tres likewise reduce the effect.

            “DUH”, …. Steven M, …. is not the above the same as claiming that atmospheric N2 and O2 decreases the “warming” effect of atmospheric CO2?

            Steven Mosher —

            I do have a new analysis using urban fraction for the entire globe. its interesting but confirms what we already know. the effect of UHI on the Global record is small.

            Well now, … SURPRISE, SURPRISE, … Steven M, …. but the UHI “footprint” on the entire globe is pretty durn small, …. if not miniscule.

            And Steven M, …. did you dun already fergeet what you stated above, … about the presence of water (rivers, lakes, oceans), green areas and trees, ….. reducing the effect of UHI on the Global record?

        • Hmm, Isn’t there a building in London that causes warming to the point of damaging automobiles? Something about sun and curved windows. Is that taken into account?

      • No, Mosh, it is also tied to airports.

        There used to be four stations that make up the CET, and one used to be at Ringway and the other at Squires Gate. Ringway is Manchester international airports, and Squires Gate is Blackpool airport. The Ringway recording site was in the middle of the taxiways, opposite the jet engine runnup bay, and the Squires Gate site was right next to the runway.

        So a large part of the recent rise in CET temps, was recording the huge rise in air traffic at Manchester, from small turboprops to vast 777s and 747s, combined with a six-fold increase in movements.

        The Manch temp site was moved from Manch to a rural location at Stonyhurst in 2005. But the new site was calibrated to the old site, and so still includes the huge rise in air-traffic from the 70s to the 00s. I also read a report that the new site at Stoneyhurst has some siting problems, but I did not find out what those were.

        But you can see how deceitful these climate people are. Here is a paper on all the possible errors in the CET, yet it never mentions ‘airport’ or ‘aircraft’ once. How on earth can any honest person investigate CET temperature accuracy, without mentioning Manchester International airport?

        https://www.metoffice.gov.uk/hadobs/hadcet/ParkerHorton_CET_IJOC_2005.pdf

        Ralph

        • the only problem is there is no measureable difference between airport and non airport stations.

          there is SPECULATION that there should be, but no systematic study establishing it.

          A while back I tried to find a bias due to airports using 1 minute ASOS data.
          hey you should be able to see spikes from jets taking off? nope.

          Shit I even went and got safety reports on jet exhaust and how the temperature diminishes with distance from the plane.. interesting stuff, but no cookie.

          • See my comments in a thread below – that is only true after the adjustments. Some huge adjustments of more than 1 degree c have been made to the CET, largely because of Ringway (Manchester Airport). See fig 1.

            UNCERTAINTIES IN CENTRAL ENGLAND TEMPERATURE 1878–2003 AND SOME IMPROVEMENTS TO THE MAXIMUM AND MINIMUM SERIES.
            https://www.metoffice.gov.uk/hadobs/hadcet/ParkerHorton_CET_IJOC_2005.pdf

            And if the adjustments have a greater amplitude than the actual tamperature variations, then what are we measuring – temperature or tamperature….?

            Ralph

    • Winter weather forecasts routinely predict rural overnight temperatures will be 3-4C COLDER than in London.

      If the Met Office used the genuine UHI of 2-4C then correcting for this in ‘homegenisation’ and adjustments would show either no global warming in the UK or quite possibly some cooling in the last 20 years.

  4. With EVERYONE knowing the effect of UHI and the amount of worldwide UHI increasing exponentially over the last 30 years, why would ANY past temps EVER be adjusted downward, or ANY current measured temps be adjusted upward?

    Does NOAA et al completely lack common sense?

    Since the UHI effect is way higher than the effect of CO2, does this mean we are all going to die from UHI?

    UHI has probably saved more humans (homeless people) than AGW has killed.

    • This is a pair of questions I keep asking and everyone ignores:

      1. Why is there a systematic trend in the residual corrections to temperatures
      2. Why do earlier temps need to be adjusted down relative to modern readings?

      What are the physical mechanisms that result in the trend in the corrections and more correction to colder values in the past? It does not make physical sense and no-one ever remarks on it.

      • ThinkingScientist – April 1, 2019 at 7:09 am

        This is a pair of questions I keep asking and everyone ignores:

        1. Why is there a systematic trend in the residual corrections to temperatures
        2. Why do earlier temps need to be adjusted down relative to modern readings?

        Answer #1: (SEE ANSWER #2)

        Answer #2: to justify their claims of increasing CAGW, the highest of the earlier recorded temperatures have to constantly be adjusted downward to insure that the newly calculated “global average temperature” shows an increase over the previous year’s calculation.

        NOTE: if any number (temperature) in a “number set” (temperature record) decreases, the “average” of said “number set” decreases. And if a new number is added to a “number set” that is less than the highest number in the “set”, the “average” of said “number set” will also decrease.

  5. An interesting study, but lets not succumb to objective bias. This result was expected, but can it be repeated, or independently verified? From the published image the UHI appears to be localized. Perhaps the entire issue is that there are large numbers of urbanites loudly complaining , but they don’t realize it’s not global, it’s local.

    • I have yet to come across any one in the UK complaining that temperatures are too hot …. yet I’ve spoken to many who wish for warmer weather at any time of the year…. and many who are worried about “Climate change” at the same time as wishing it were warmer …..

      • Old England – Quite. Also, to ‘mitigate’ against a warmer world we are mandated to insulate our houses to keep the heat in. The double irony is that well insulated houses will be difficult to cool down during the heat waves we have every year.

        • And, as is typical of the UK, each yearly heat wave is never at the same time of year so we are lucky if they coincide with a national holiday, with the exception of 1976

      • Not surprising, since we, as a specie, have a natural habitat coming from the 40 degree C warmth of Ethiopia/Sudan.

        Most of the globe, for us as a species, is way too cold. That is why we have to adapt ourselves (with clothes) or our environment with buildings (caves of old) and with central heating (fires of old).

        This planet rather than being too warm, is in fact too cold. Heck, the planet is in an ice age, so what do you expect? However, fortunately for us, we are living in a short lived interglacial episode (the Holocene) where temperatures are more benign, and more suited for us, as a species, but this interglacial will not last forever and probably only has about another 10,000 or so years to go.

        • It is what you are acclimatized to. I have a sister-in-law who lives on the Oregon coast and absolutely ‘melts’ when the high temperatures get above 70F (21C) for several days in a row. I also have a friend who was raised in Brazil and only takes off the sweaters and coats when the temperatures are above 90F (32C).

  6. 1.7 K is 1.7 C above absolute zero K.

    Kelvin is the scale, Celsius the units.

    Rankine is the scale, Fahrenheit the units.

    • Using the word “increased” or “decreased” implies a delta Temperature. And the use of ΔT explicitly indicates a change in T. Whether the scale is K, C, or F doesn’t really matter.

      Examples:
      “annual averge (sic) T min would have increased by 1.90 ± 0.88 K.”
      “an average increase of 1.6 ± 1.2 and 0.8 ± 2.1 K”
      “significantly increased the daily minimum 2‐m temperature in the United Kingdom by up to 1.70 K.”
      “annual average ΔT min, an urbanisation effect of 1.90 ± 0.88 K is found”

    • Kelvin is the scale, Celsius the units.

      Sadly, you are wrong. They are two different temperature scales of which the units are the same size.

      The kelvin ( K ) is the S.I. unit of temperature and is part of many derived units like W/m^2/K , there is no reason not to state a temperature difference in kelvin, in fact it is the official SI unit.

      Celsius the units

      Wrong again. The unit of the Celsius scale is defined as the degree Celsius.

  7. So, if we were to extend this result to all urbanized areas of the planet, what would happen to the GAST? would adjusting for it (lowering Tmin at each urban/airport station) decrease Global T(AVG) anomaly to about 0.0K +/- O.5k?

    • applied to GAST?

      Look at the map of UK

      See all that BLUE

      Guess where almost all the stations are?

      • “Steven Mosher March 31, 2019 at 1:39 pm
        applied to GAST?
        Look at the map of UK
        See all that BLUE
        Guess where almost all the stations are?”

        All of that “BLUE” means that Tmin UHI is greater than 0.0°C, frequently substantially higher.

        • Guess again.

          take a guess how much of the map is below .1C.

          THEN understand that this is TMIN.

          TAVG = (tmax+tmin)/2.

          So if Tmin has a .1C bias whats that do to Tavg?

  8. “The urban heat island (UHI) develops through changes to the surface energy balance due to anthropogenic modifications to the land surface.” How about the dissipation of heat from energy use sources? Lights, motors, heaters, transportation vehicles, etc.? Don’t they count?

      • SM
        Anthropogenic heat flux days a small role.

        How much , is it estimated, calculated, what is the data and outcome of the study.
        How has it been qualified.

        0.5C since WW2 ?

        It would be difficult being your dentist, it would take at least a week to get one tooth out.
        Regards

        • Why be so off-hand. He gave a valid answer. If you want number go find them, don’t expect him to do the work for you. You asked the question.

          Although we do burn huge amounts of energy, it is still small compared to the 1kW/m^2 falling from the sky. Globally it is a small factor, though it probably is a significant part of UHI effect on Tmin.

        • “How much , is it estimated, calculated, what is the data and outcome of the study.
          How has it been qualified.”

          anthropogenic heat flux has been studied by a lot of folks. DOH!

          There is this really cool idea called search. Some company named google does it.

          here is one of many

          https://www.sciencedirect.com/science/article/pii/S1352231016309232

          or you could spend 12 years studying this particular issue.

          Now, after you read one paper, you will find this thing called REFERENCES!
          imagine that! so you read all those papers. and they have references TOO!
          and then you read citations.. which pepers cited the paper.. IMAGINE THAT!

          And after you study study studythen you too can go comment on blogs and have idiots
          ask you to do their homework for them

          • Steven thanks for the reference. Much appreciated. My apologies for having to ask you for a reference for your statement. Yes I am aware of Google, thanks again for the guidance. I simply thought that you as the “Data Guy” you may be able to in a simple sentence give a reference to save me the 12 years.

            Greg
            Normally Steven or others would be terse for no reference given by others. Look at the way he treats others. Down under we have a sense of humor, and the saying “getting information is like pulling teeth” is a light-hearted way to do it. It was tongue in cheek to keep the oral thing going. I guess the humor changes as one crosses the equator, and on different individuals. Oh well.

            If you take the trouble to re-read in a quiet polite tone you may see it in another light. And thanks for your own comments.

            Are you Greg from climategrog ??

    • Markl … hence …. man made warming. This is the real anthropogenic Warming. Since it is included in the average, it influences the “global” average, thus you get man made global warming. CO2 on the other hand has little to no effect on temperature change. It’s only role is as a component of the GHG blanket that is pretty much a constant and dominated by water vapor.

      • “hence …. man made warming.” Yes and I have said for years it’s the only AGW that is measurable. And if we completely eliminated fossil fuels as the energy source it would still be present.

  9. And all those volcanoes which dissipate all this energy since 4.5 billions years :

    – where did it went ? Where does it go ?

    Perhaps it is radiated into space by some trace gases which are active in the infrared spectrum ?

    Who knows ?

    🙂

    • It has long been suspected that UHI is under-corrected.
      If UHI contamination was fully corrected, NOAA and NASA/GISS wouldn’t be able to keep cooling the past while warming the recent years to the extent they need in their never ending adjustments of historical records. Combine that with loss of rural stations through the decades and they have set-up a system to synthesize increasing warming to approach the models outputs.

      • Trouble is Joel, if you remove UHI you have very little in the way of positive anomalies to smear up to 1200km away. Give them a break, AMO heading cold,they going to need all the help they can get just to keep the wolf from the door in the not too distant future.

      • “If UHI contamination was fully corrected, NOAA and NASA/GISS wouldn’t be able to keep cooling the past while warming the recent years ”

        Except that the homegenisation that makes a jot of difference to the warming trend is one that reduces it…..

        http://www.realclimate.org/images/GISS-adjustments.jpg

        And please link to a study that finds that thermometers contaminated by the UHI, have any material effect on tha calculation of GMST.
        I there were then this place would surely know of it.

  10. Stephen

    The Met Office use a 0.2C adjustment which they are currently re-examining that to see if they should allow more. That is for CET.

    This from their web site

    “Both series are now kept up to date by the Climate Data Monitoring section of the Hadley Centre, Met Office. Since 1974 the data have been adjusted to allow for urban warming: currently a correction of -0.2 °C is applied to mean temperatures”

    They make no adjustments for the usual records most commonly used, which are the composite ones from 2010 covering all four home countries..

    With that criteria 2018 tied with 3 others as the hottest summers ever using the 1910 records but CET which is more consistent in its use of stations, was still notably warmer. The difference is that the 1910 records are not adjusted for UHI. I have been exchanging a number of emails with the Met office regarding these figures. It has been over a year since they started looking again at uhi so lets hope they come up with some pronouncement soon

  11. So if UHI account for all of the warming of the last 50 years – does that mean without UHI, the world is actually cooling ?

    • No.

      1. Stations tend to be in the blue areas, not the red.
      2. 70% of the record is oceans.

      • 70 % in the oceans. LOL, we have no accurate way to measure the oceans. Any number representing the ocean temperature is a joke. Any one who thinks such a number shows something that is real is a fool, those that present that number as real is a con men.

        • “70 % in the oceans. LOL, we have no accurate way to measure the oceans. Any number representing the ocean temperature is a joke. Any one who thinks such a number shows something that is real is a fool, those that present that number as real is a con men.”

          Lets see. You believe there was an LIA, but you regard data showing it is warmer now than in the LIA is a joke?

          You believe the past was cooler, but you believe the evidence showing it is warmer now is a joke.

          Strange.

          • No, he is yet another genius who reads one thing but it gets mangled before it gets to the brain. He then starts ranting about his brain fart instead of what was written.

            2. 70% of the record is oceans.

            Indisputable , 70% of the surface record is SST, 30% land SAT. So UHI can only affect 30% of the global record.

            70 % in the oceans. LOL

            He seems to be getting confused with OHC.

        • However …. there is a near perfect correlation between SST and so called Global Temperature. What does that tell you? It tells me that SST is what drives the observed surface temperature records, and thus, regardless of whether or not it is accurate, it serves as testimony that CO2 has practically noth8ng to do with temperature change.

          Climate Science needs to be more heavily investigating what drives SST, as what ever drives SST is what determines GAST. Of course, since CO2 emits LWR and has no concrete mechanism to drive up SST, …. they’ll have to abandon their little pet theory ….

          • “Of course, since CO2 emits LWR and has no concrete mechanism to drive up SST, …. they’ll have to abandon their little pet theory ….”

            Dear, oh dear, that myth again.
            Why do you think that the reduction of the climate systems’s ability to cool to space “has no concrete mechanism” to warm the oceans?
            You really think that reducing the ocean skin’s ability to cool would not warm them?
            Basic thermodynamics has it that heat transfer to the radiating surface is greater when there is a maxima DeltaT towards that radiating surface from the cooling body.

            https://cyber.sci-hub.tw/MTAuMTA4MC8wMTQzMTE2MDMxMDAwMDk1ODgw/minnett2003.pdf

            https://moyhu.blogspot.com/2010/10/can-downwelling-infrared-warm-ocean.html

          • Anthony …. I’ve read that before, as well as the study covered on Realclimate regarding this issue …. and it remains, there is no empiric evidence to support it. This is a simple case of people trying to prop up their pet theory with the “virtual world”, doing mathematical gymnastics with the lights off, cause they don’t know all the parameters, can’t quantify them, and thus cannot conjure up the correct mathematical model. ……. i.e. …. they are mathematically describing something that doesn’t exist, but saying that it defines what does exist.

          • Deanster:

            Your evidence for it is in the study and basic thermodynamics.
            As with the GHE in total the Earth cannot be replicated in the laboratory.
            The GHE is one that involves energy exiting the Earth being resticted and some of it being emitted at altitude and less efficiently due to much colder temps.

            When land cools overnight there exists a deltaT between the surface emitting layer and heat stored below.
            That is a heat flux. It flows at its greatest when skies are clear and the surface skin is coldest.
            When cloud encroaches the surface warms and the heat flux from below slows.
            Same with the ocean skin.
            Terrestrial LWIR does not warm the oceans directly but it slows its cooling by the same method.
            (Sceptic) Roy Spencer has done some basic experiments ….

            http://www.drroyspencer.com/2015/06/can-infrared-radiation-warm-a-water-body-part-ii/

      • Odd comment Mosher.

        Black is 0.0°C UHI for Tmin.
        Blue colors are higher than 0.0°C with many higher than 0.2°C.

        I haven’t noticed many oceans in the UK. 70% you claim, riight…

  12. While Anthony’s project is definitive, I would like to see a study where this is actually measured for a large metropolis and surrounding suburban and rural areas. Perhaps the satellite data could be used. I understand that the urban heat island adjustment for NYC has changed significantly, but used to be almost -7°F, and is now near -2°F. I am not sure how you can explain the change in the correction when even more people live in NYC and surrounding areas no than when the value was -7°F. Also, any station using a correction of this type where the magnitude of the correction is as large (or much larger in this case) than the size of the change in temperature where the world is going to end (2°C or 3.6°F) should not be used for determining the average temperature of the world.

  13. The paper is a good start, but I would note these limitations.

    1. The urban cover dataset they used has 250m resolution. This is adequate, but they had 100m data
    and didnt used it because it takes longer to compute. I dont buy this. I’ve done the entire globe
    using 30m data and while it takes a week or so for the calculation its worth it to cross check the
    the 250m data against the higher resolution data. One reason this is important is that
    all land class data has producer and user error ( non urban classified as urban, and urban miss classified
    as non urban)

    2. They have only used 34 stations in their regression and they dont have a large enough sampling
    across the range of fractions to uncover UHI at low urban fractions. The key issue is not
    UHI at HIGH urban fractions ( 100%) because the vast vast majority of stations do not have
    high urban fractions. The key issue is what is the UHI effect at small urban fractions.

    3. They didnt assess UHA Urban Heat Advection. The excess heat at the city core advects to suburban
    and rural areas under certain wind conditions . UHA falls of exponentially, but it cant be ignored

    In general the study is in line with other findings. UHI hits hit Tmin rather than Tmax. This is important for the global average since Tavg = (Tmin+Tmax)/2. Using Tavg, halves the effect of UHI. Its also important to note that they took monthly temperatures. hence they get a max effect of 1.9C on Tmin. Usually, when
    people look at UHI they look at isolated DAYS and select the days with the highest UHI. So its good to see folks looking at longer periods. lastly if you look at the all blue map… where do you suppose
    the vast vast majority of stations are? in the red areas or blue?

    Care to wager?

    Last question: what is the IPCC estimated maximum impact of UHI on global land datasets?

    a) 0C
    b) .1C
    c) .2C
    d) other

  14. slight o/t but can someone explain to me how the DMI reports almost normal arctic temps but sea ice is dropping to -3 SD? If this 1.7 K holds up the CO2 charade soon goes belly up.

    • billtoo, at this time of year the peripheral sea ice is mostly thin ice that has formed late season outside of the main Arctic basin and is subject to rapid loss as well as extension and compaction as a result of wind direction. This can show on the extent charts as loss when it in reality it is compaction or the ice spreading beyond the 15% grid area concentration required to meet the definition of ice coverage.

      Along with the Bering Sea a large tongue of this mostly thin and highly mobile sea ice was further south in Baffin Bay/Labrador Sea than has been the norm in recent years. These areas are well outside the area of DMI measuring/modelling of 80n ,hence subject to higher temperatures as well as more susceptible to the influence of waves.

      The vast majority of Arctic sea ice is mobile right through the year ,water temps and weather are far greater factors when it comes to sea ice thickness and extent than air temperature north of the 80th parallel.

    • DMI doesnt report arctic temps.

      They report the results of a simulation north of 80deg.

      and at this time of the year melt is dominated by bottom melt ( warmer water)

  15. One only has to get in a car and drive out into the countryside to see the UHI effect in practice . The outside temperature drops by a good 3 C on a winters night within a mile of urban areas. all those centrally heated houses add up.

  16. Years ago, I was staying in a hotel in downtown Charlotte. This was December and the temperature was about what is considered normal. Some jerkwad pulled the fire alarm in the middle of the night and so we had to evacuate. I was wearing some loose running shorts and a T-shirt, no socks or shoes. Despite the temperature, when I stood next the building I was not cold. Nobody was. The hotel was brick on the lowest level. The concrete and brick radiated heat and all of us were fine until the fire department cleared the building.

    Our house is brick. Whenever it snows, the driveway near the house always takes longer for the snow to accumulate than the opposite side of the concrete driveway. The brick radiates heat. Human structures absorb and radiate heat. If you want to see this effect with your own eyes, take an early morning drive on a day with no wind from a mostly rural area to a large city, or the other way around. The temperature gauge on your vehicle will increase (or decrease) several degrees in a single hour of driving toward (or away) from the city, much more than by the natural heating of the day.

    The average temperature may be going up, but I seriously doubt the daytime highs are increasing dramatically. Human structures are holding heat in, thus increasing nighttime lows, thus increase the average temperature.

  17. Nick Schroeder: Kelvin and degree Celsius are both units, and 1K=1degree C.
    Kelvins and degrees Celsius are both temperature scales.Celsius temperature=T-273.15 where T is in kelvins.

  18. One of the things that has bothered me about 2-metre temps in a city is insufficiently granular sampling.

    To my knowledge, none of the thermometers used for meteorological records is inside a building that is being heated and/or cooled to suit occupancy by people. Undesired heat is pumped back ouside. Undesired interior cold air is warmed, heat which eventually is lost to the environment. In effect, the exterior air is warmed to establish consistent indoor temperature, but never including interior temps in averages.

    In a modern city, these temp-controlled spaces extend to hundreds of feet in elevation, and vent their heat (via exhausts) at multiple levels… places varying from the sidewalk to the roof. Some say that ‘we live on the surface, not in the lower troposphere’. This is not an accurate representation of the places we heat and cool in a city.. those extend well into the lower trop, as is evidenced by the plumes of condensentaion appearing above commercial buildings on a cold winter morning. Those plumes show that latent heat has been relocated to the outside, and converted to sensible heat.

  19. It seems obvious that the UHI effect is in direct relationship with where the weather stations are located. What is the difference in temperature increase in recorded urban temperatures versus rural?

    • rwisrael

      “What is the difference in temperature increase in recorded urban temperatures versus rural?”

      The worldwide GHCN station data set has in its revision “V3” a station list including this difference on a per-station basis:
      – stations are marked “R” for “rural”, “S” for “suburban” and “U” for “urban”;
      – stations have been given a “nightlight factor” from “A” for “low” up to “C” for “high”.

      Of course, everything on Earth is subject to changes. And due to population increase, rural stations will always rather become suburban than would urban stations ever move down to rural ones!

      Nevertheless, I made two years ago a little comparison for the Globe as a whole, between
      – the GHCN V3 subset of all rural stations with nightlight level “A” (about 33 %);
      – the rest.

      https://drive.google.com/file/d/1nqBimMq4kHRmZtUekhLHDNh7K4V9fY8X/view

      It should be clear here that the graph shows anomalies i.e. departures from a common mean, which were computed on a per-station basis, and that therefore only those stations were considered which provided for sufficient data within the reference period (1981-2010).

      One of the many reasons to perform a per-station computation of departures is that their use become less dependent of the stations’ characteristics.

      My question nevertheless: why should we ignore warming due to UHI? It is very certainly not due to CO2, that is absolutely evident!

      But… isn’t it a consequence of Mankind’s activities?

      • GHCN V3 metadata with respect to nighttime lights is not very good.

        1. The dataset they used was not really fit for prime time ( same with early work by hansen)
        They used the wrong nightlights data, same as early hansen work. Hansen has fixed
        his, GHCV v3 still uses the old bad data.

        2. Nighlights doesnt work as well as urban fraction for two reasons
        A) you have places with Lights but no urban fraction.
        B) you have places 100% urban but no lights
        Nighlights is now regarded as a proxy of electrification.. not necessarily urban

        3. For more details on why nightlights isnt a good metric, see the paper this post covers

        • Steven Mosher

          I fully agree with you.

          But nevertheless, discovering the poor difference between ‘rural’ and ‘suburban/urban’ was for me very interesting.

          Of certainly even greater interest would be to collect all places on Earth showing an increase of TMIN as described in the head post, and to where it doesn’t…

          • I have the entire world mapped at 30meters showing urban versus non urban, so its doable.

            good on you for doing the work!

  20. So if you live in cities kids, please beware of mornings, they’re past the tipping point already.

    …. and then carbon dioxide’s gonna get yer too. Vote leftybollox and be led to the promised land. It’s your only hope.

  21. It’s hard to refute the anthropogenic origin of urbanization. Although there are some very extensive termite cities that do their bit to help keep this little planet from sliding into another chill cycle.

  22. now if we could just stratify our world and regional temperature by urban and rural and show them side by side over the years. My bet would be that those regions that are rural would show very little warming and those regions that are urbanizing would show increasing warming.

    • I agree but I don’t believe that even those rural areas are not effected by UHI. I suspect that most if not all of the modern rise in temps is due to urbanisation. How many hundreds of millions of engines are operating at any one time? What is the entire mass of artificial heat bank? It makes a huge difference. You can see it when looking at the lack of frost along the base of a brick wall on a freezing morning.

      • I remember studies from way back when I was going through basic meteorology that even in a village of thirty homes there was a measurable UHI effect.

  23. I’m sure I read Tokyo is recording up to 10C!.. higher than it did several decades back.

    Is all the 10C removed in the calculations?

    • You fell for the “cool cities” propaganda

      In order to promote cool city technologies folks decide to look at UHI MAX!

      You design your test to look at certain days

      A) cloudless
      B) no wind
      C) no rain in the preceeding days.

      If you can do that you can find uhi max of up to 10C. there are 365 days in the year.

  24. From the article: “This paper finds through the method of observation minus reanalysis that urbanisation has significantly increased the daily minimum 2‐m temperature in the United Kingdom by up to 1.70 K.”

    Urbanisation increases the daily minimum within urban areas, not the entire United Kindom.

    Concrete and buildings and pavement absorb a lot of heat during the day and radiate it during the night.

    • “Concrete and buildings and pavement absorb a lot of heat during the day and radiate it during the night.”

      yup. This can also leads to UCI.. urban cool islands during the day.

      But if you get a radiative canyon, then Tmax can be increased

      • “This can also leads to UCI.. urban cool islands during the day.”

        Well, there’s something I never heard of. Would you mind expanding on that, Steven?

        You learn something new every day on this website. 🙂

  25. I live in a rural area about 40 miles from a city of 400,000, and when the winds settle down and no weather fronts are coming through, it is always several degrees warmer in the big city than in my area.

    • Yup.

      UHI is worse in certain synoptic conditions. good thing these conditions dont happen every day.

  26. I have had many occasions to drive through Oklahoma City or Tulsa, OK and then back in fairly short time intervals. Compared to the surrounding countryside, the central parts of the cities are generally warmer when traversed in either direction and the effect is just as pronounced in mid afternoon as at night. I find it hard to believe that daytime maximum temperatures are not similarly higher in urban areas of England.

    • “I find it hard to believe that daytime maximum temperatures are not similarly higher in urban areas of England.”

      They have a sample of 34.
      You have a sample of 2 or 3.

      Yet you find it hard to believe. That’s weird.

      In GENERAL UHI will hit Tmin and not impact Tmax. In their paper they give some of the reasons
      why this is so. HOWEVER, you can find areas in SOME cities where tmax is ALSO impacted. you can even find cities that are cooler than the rural suroundings, it all depends on the city. but in general, what they found is accurate

      Every city is different. Some have cool zones ( urban cool islands) but NONE is the same temperature
      in every location. One location may show a 1C diference with the rural surroundings and 1km away
      the difference may be 3C, or -1C.

  27. Urbanization is not, however, responsible for the increase in extreme weather in the UK in recent decades… that’s down to climate change.

    • “Urbanization is not, however, responsible for the increase in extreme weather in the UK in recent decades”

      I agree that UHI does not cause extreme weather, but I see no evidence of extreme weather in the UK in recent decades attributable to CO2, either. That was what you were implying, wasn’t it?

    • Increase in extreme weather. Hilarious. You want to just read a little bit of English history of the last 700 years and then come back and suggest with a straight face that there is an increase in extreme weather in England. I can’t speak with much conviction for the wider UK, but I think you’ll find at least Scotland is similar…

  28. TYPO in the first paragraph of the Abstract—change “and” to “an”:

    “… and ERA‐Interim reanalysis temperatures was estimated.”

  29. Urbanisation is also tied to airports.

    There used to be four stations that make up the CET, and one used to be at Ringway and the other at Squires Gate. Ringway is Manchester international airports, and Squires Gate is Blackpool airport. The Ringway recording site was in the middle of the taxiways, opposite the jet engine runnup bay, and the Squires Gate site was right next to the runway.

    So a large part of the recent rise in CET temps, was recording the huge rise in air traffic at Manchester, from small turboprops to vast 777s and 747s, combined with a six-fold increase in movements.

    The Manch temp site was moved from Manch to a rural location at Stonyhurst in 2005. But the new site was calibrated to the old site, and so still includes the huge rise in air-traffic from the 70s to the 00s. I also read a report that the new site at Stoneyhurst has some siting problems, but I did not find out what those were.

    But you can see how deceitful these climate people are. Here is a paper on all the possible errors in the CET, yet it never mentions ‘airport’ or ‘aircraft’ once. How on earth can any honest person investigate CET temperature accuracy, without mentioning Manchester International airport?

    https://www.metoffice.gov.uk/hadobs/hadcet/ParkerHorton_CET_IJOC_2005.pdf

    Ralph

  30. Gosh! A map that shows Norwich- quite a rarity! I wonder how much of our hot-spot is centred on the concrete monstrosity of the UEA : all those computers blazing away in the CRU must contribute something.

    • Most of the man made warming comes from one small round building: the Climatic Research Unit.

    • More likely UEA is an outstanding centre of creative writing and the least successful ones we transferred to climate studies when their work became so fanciful as to be implausible to all but those in the creative arts rather than mainstream public.

  31. Readers here might like to revisit the fairly long but reference-rich essay I wrote about UHI with some Australian examples, just before Christmas last year (not a good date for serious work releases).
    It remains unexplained by all so far, how daily maximum UHI effect temperatures up to 8 deg C above surroundings have been measured for several major cities, yet the present paper under discussion here says little Tmax effect is observed by them in UK. It gives a possible interpretation that UHI can be severe, but it can also be short-lasting over a given day or week or so, and not happen many times a year. I do not support that impression because it is getting too like special pleading rather than strict observation.
    Geoff
    https://wattsupwiththat.com/2018/12/20/the-science-of-the-urban-heat-island-effect-is-pathetic-and-misleading/

    • Geoff Sherrington

      I read your excellent WUWT head post last Dec (and also your fair communication with St. Mosher in the comment thread).

  32. If I pull up the Met Office temps (https://www.metoffice.gov.uk/climate/uk/summaries/datasets) and average them over the past 20 years for the UK, starting 1999 in the wake of the 1998 climate shift …

    Max C
    Winter 1999-2008 7.32C
    Winter 2009-2018 6.69C
    Down 0.63C

    Spring 1999-2008 12.24C
    Spring 2009-2018 12.25C
    up 0.01C

    Summer 1999-2008 18.92C
    Summer 2009-2018 18.91C
    Down 0.01C

    Autumn 1999-2008 13.43C
    Autumn 2009-2018 13.31C
    Down 0.12C

    Annuals 1999-2008 12.99C
    Annuals 2009-2018 12.84C
    Down 0.15C

    Min C
    Winter 1999-2008 1.56C
    Winter 2009-2018 1.01C
    Down 0.55C

    Spring 1999-2008 4.27C
    Spring 2009-2018 4.03C
    Down 0.24C

    Summer 1999-2008 10.55C
    Summer 2009-2018 10.41C
    Down 0.14C

    Autumn 1999-2008 6.66C
    Autumn 2009-2018 6.56
    Down 0.10C

    Annuals 1999-2008 5.76C
    Annuals 2009-2018 5.55C
    Down 0.21C

    Maybe UHI has plateaued and a cooling climate, particularly in winter, is making the UK even chillier. It seems a bit weird that all those UK school kids protesting a couple of weeks ago about the warming climate did so in a cooler climate than when they were born.

    • Chris Gillham

      “It seems a bit weird that all those UK school kids protesting a couple of weeks ago about the warming climate did so in a cooler climate than when they were born.”

      https://drive.google.com/file/d/1szN7r90gAuiPfelY0wrnvnXvFmJPM9_C/view

      What would you have told us within the big drop from 1960 till 1965, as you saw that the UK estimate for 1938-1965 would go below -0.2 °C / decade?

      Do you have an idea about Norway’s estimate for 2000-2018? They won’t need Gran Canaria anymore if it continues there that way 🙂

  33. ralfellis and the airport heat syndrome

    Regularly, this commenter writes about the same stuff concerning Jumbojet heat effects at Manchester Airport station in the UK.

    Here is, for the period 1979-2018, a comparison of
    – the average of all available GHCN daily UK stations
    with
    – the GHCN daily ‘RINGWAY’ station (within Manchester International Airport).

    Trends in °C / decade for 1979-2018
    – UK average: 0.22 ± 0.04
    – RINGWAY: 0.13 ± 0.05

    Trends for 1979-2004
    – UK average: 0.47 ± 0.07
    – RINGWAY: 0.45 ± 0.1

    What does ralfellis mean here?

    Maybe I should spend a full day in obtaining all these highly suspect weather stations worldwide located within big airports, and compare their average with that for the Globe??

    • You are not giving us the full information here – your figures are post-adjustments.

      These temperatures were given a negative 0.5 degree c adjustment, due to UHI, between 1960 and 1980. And many of those adjustments were said in the report to be ‘arbitary’. Unfortunately, I cannot find the UHI adjustments for Ringway post 1980.

      But this gives us a problem – if the UHI adjustments are of the magnitude of 0.25 degrees c per decade, then the adjustments are greater than the proposed warming. So what are we measuring here – global warming, or a meteorologists guestimate about UHI adjustments?

      And do note that the Ringway site was moved to Stonyhurst because of the unreliability of Ringway. So there WAS a problem with Ringway (ie with having a temperature monitoring station in the middle of Manchester International Airport). But as you know – those problems will remain forever, hidden in the middle of the CET dataset. (Unless they can find a better rural dataset, and go back through the CET and replace all the Ringway records with the alternate records.)

      Ralph

      • Looking at the CET dataset – perhaps they simply stopped making UHI adjustments in 1980. In which case that huge rise in CET since 1980 may be predominantly UHI. Do you have the adjustment record, post-1980?

        R

      • ralfellis

        … your figures are post-adjustments.

        These temperatures were given a negative 0.5 degree c adjustment, due to UHI, between 1960 and 1980. And many of those adjustments were said in the report to be ‘arbitary’.

        Unfortunately, I cannot find the UHI adjustments for Ringway post 1980.

        Oh Noes! This is no more than typical pseudoskeptic nonsense. The less some know, the more they manage to guess, claim and pretend.

        Here is the data about which you pretend it has been adjusted:
        https://drive.google.com/file/d/17rZtMUSMc-bE5LH5p6VAjEVOEt9UDvy8/view

        It is again a comparison between Manchester Airport data I found for 1951-2004, and the whole UK average for the same period. (Manchester data begins with January 1794, but is highly incomplete.)

        *
        Look at your wonderful ‘negative 0.5 °C UHI adjustements’… This is so ridiculous that I can’t even laugh about it.

          • ralfellis

            “You obviously don’t understand how these datasets are derived.”

            I very obviously understand that you publish here an anonymous, nonsensical graph made by hand, and relying on no valuable, reproducible source at all.

            Your behavior is typical for people who lack any experience, and thus believe in anything what fits to their narrative, no matter how wrong it is.

            What I published can be reproduced using correct data, originating from verified datasets you would never be able to contradict or falsify other than with such unscientific methods.

          • Anonymous graph..? If you had bothered to look I have already published a link to it. It was published by Parker et al, in their 2005 paper…

            UNCERTAINTIES IN CENTRAL ENGLAND TEMPERATURE 1878–2003 AND SOME IMPROVEMENTS TO THE MAXIMUM AND MINIMUM SERIES.
            https://www.metoffice.gov.uk/hadobs/hadcet/ParkerHorton_CET_IJOC_2005.pdf

            But I see you know absolutely nothing about how these ‘tamperature’ datasets are created, and the many (often unjustifuable) adjustments that are applied to them.

            And I ask you again – if the adjustments have a greater amplitude than the actual tamperature variations, then what are we measuring – temperature or tamperature….?

            Ralph

  34. “From the Royal Meteorological Society.
    […]The urban heat island intensity (UHII), which describes increased temperatures in urban areas, has long been known and attempts have been made to quantify it for many years (Mitchell, 1961; Oke, 1982).”

    Doesn’t look very good when the last cited attempt to quantify it was in 1982. Perhaps they were just too busy running after carbon dioxide.

  35. I´m sorry, but I have to ask few very stupid questions.

    Is all warming on this planet manmade? If it warms 1C, what part of it is manmade? Is there not natural warming anymore?

    Thank you, and sorry.

    • F1nn

      I go with Roy Spencer (UAH). He is very pragmatic and tells us: 50% natural, 50% man-made.
      Those who reject his view are in my mind either warmistas, or… coolistas.

  36. The urban heat island intensity (UHII), which describes increased temperatures in urban areas, has long been known and attempts have been made to quantify it for many years (Mitchell, 1961; Oke, 1982).

    I would dispute the claim that attempts have been made to quantify it. My daughter and I have both in widely different industrial and commercial firms both met ex climate scientists who were denied any grants after attempting to put projects in place to quantify this effect. This is in the UK but I know for certain this has also occurred in two European countries , Australia and the US.
    In both cases the UK cases grants were refused as being liable to undermine other more major projects of the universities concerned.

  37. Someone should analyze the connection between the strength of empirical findings on UHI and the volume of Mosher’s disparaging comments. The persistently high correlation would be revealing.

  38. The considerable difference between urban and rural temperatures as in
    such countries as the UK, reminds me of Stalin’s famous comment about
    voting. “It does not matter how many people vote, but it does matter who
    counts the votes.”

    So of course it does matter just where the devices measuring the temperature
    are situated.

    I strongly suspect that just about all of the apparent increase in the
    measured temperatures are due to the Heat Island Effect and not on CO2
    levels. And I am sure that the Warmers lobby are well aware of this fact.

    MJE VK5ELL

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